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41.
Corrado Massa 《Astrophysics and Space Science》1994,215(1):59-72
The possibility that the cosmological term is proportional toGU, whereG is the gravitational coupling andU is the mass density of the universe is proposed and discussed. WithG = constant, a cosmological model is obtained, which avoids the flatness and horizon problems and does not affect the well known predictions on the cosmic helium abundance which come from standard big bang cosmology. In such model, the deceleration parameter is a null constant, there is matter creation process throughout the universe at the rate 10–47 g cm–3 s–1 and the cosmological term varies asH
2 =t
–2, whereH is the Hubble constant andt is the cosmic time.The possibility of a time-dependentG is then considered. The main consequence of this is that there is a mass creation process on the local scale; the rate of mass creation inside a body of massM is dM/dt =M H. In Section 6 it is suggested that the new matter might be in the form of neutrinos. This suggestion leads to an interesting consequence in celestial mechanics: the radius of a binary system should depend on time according to the nature of the components (the radius of a binary star should decrease, the radius of a planet-moon system should expand, and the orbital radius of a planet should stay constant). 相似文献
42.
A revised Italian strong motion archive has become available since July 2007, including all the records of the strongest events
occurred from 1972 to 2004. It contains the uncorrected and corrected accelerograms and the metadata relevant to seismic events,
recording stations and instruments added after a careful revision. The availability of this archive allowed us to perform
a first step towards an update of the reference ground motion prediction equations for Italy, which were evaluated by Sabetta
and Pugliese in (Bull Seismol Soc Am 77:1491–1513, 1987), for peak ground acceleration and velocity, and subsequently extended
to the 5% damped pseudovelocity response spectra in 1996. A subset with the 27 major earthquakes occurred in Italy from 1972
to 2002, in the magnitude range 4.6–6.9, was extracted and 235 good quality waveforms were selected, recorded at distances
up to 183 km. The goodness of fit of the Sabetta and Pugliese (Bull Seismol Soc Am 86:337–352, 1996) model was explored using
two independent statistical approaches (Spudich et al. Bull Seismol Soc Am 89:1156–1170, 1999 and Scherbaum et al. Bull Seismol
Soc Am 94:2164–2185, 2004). The results obtained show that the Sabetta and Pugliese (Bull Seismol Soc Am 77:1491–1513, 1987)
does not adequately fit the new strong-motion data set, for its small standard deviation and its non-zero bias. In particular,
the most noteworthy result is that the Sabetta and Pugliese (Bull Seismol Soc Am 77:1491–1513, 1987) over-predicts peak ground
acceleration and velocity at rock sites. New coefficients for the prediction of horizontal peak ground acceleration, peak
ground velocity and acceleration response spectra, adopting the same functional form in Sabetta and Pugliese (Bull Seismol
Soc Am 77:1491–1513, 1987), were then evaluated in order to fit the new data set. This paper illustrates the steps made to
update the existing ground motion prediction equations for Italy, discusses their limitations and provides the basis for future
developments. 相似文献
43.
Corrado Massa 《Astrophysics and Space Science》2008,317(1-2):139-141
We find that Einstein’s like field equations with coordinate-dependent cosmological “constant” Λ(x i ) imply a non geodesic law of motion for test particles moving in a continuous distribution of incoherent matter (“dust”). The deviation from the geodesic law depends on the derivatives ?Λ/? x i and, in the weak field approximation, causes an anomalous acceleration A～(Vc 2/γ ρ)?Λ/? t+(c 4/γ ρ)?Λ/? r where V=dr/dt, c=the speed of light, γ=8π G with G=the gravitational coupling, ρ=the mass density of the cloud, r and t are the radial and time coordinate respectively. Reasonable assumptions on Λ=Λ(t) give A<10?8 cm/s2 when ρ>10?29 g/cm3 i.e. in all known astrophysical systems. A possible connection with the anomalous Pioneer acceleration is shortly discussed in the case of a cosmological “constant” coupled to matter. 相似文献
44.
Corrado Massa 《Astrophysics and Space Science》1993,209(2):309-312
The Weinberg relation (which connects the Hubble constantH to the mass of a typical elementary particle) is an empirical relation hitherto unexplained. I suggest an explanation based on the Zel'dovich energy tensor of vacuum in a Robertson-Walker universe with constant deceleration parameter,q = const. This model leads to
- the Weinberg relation,
- a varying cosmological term Λ scaling asH 2,
- a varying gravitational constantG scaling asH,
- a matter creation process throughout the universe at the rate 10?47 g s?1 cm3,
- a deceleration parameter in the range -1 to 1/2, which allows a horizon-free universe and makes the lawG/H = constant, consistent with the Viking lander data on the orbit of planet Mars.
45.
46.
Paolo Augliera Ezio D’Alema Simone Marzorati Marco Massa 《Bulletin of Earthquake Engineering》2010,8(5):1091-1104
The necessity of a dense network in Northern Italy started from the lack of available data after the occurrence of the 24th
November 2004, Ml 5.2, Salò earthquake. Since 2006, many efforts have been made by the INGV (Italian National Institute for Geophysic and Vulcanology), Department of Milano-Pavia (hereinafter INGV MI-PV), to improve the strong-motion monitoring of the Northern Italy regions.
This activity led to the installation of a strong-motion network composed by 20 accelerometers, 4 coupled with 20-bits Lennartz
Mars88 recorders, 12 coupled with 24-bits Reftek 130 recorders and 4 coupled with 24-bits Gaia2 recorders. The network allow
us to reduce, in the area under study, the average inter-distances between strong-motion stations from about 40 km (at November
2004) to 15 km. At present the network includes nine 6-channels stations where velocity sensors work together the strong-motion
ones. The data transmission is assured by modem-gsm, with the exception of four stations that send data in real time through
a TCP/IP protocol. In order to evaluate different site responses, the stations have been installed both in free field and
near (or inside) public buildings, located in the center of small villages. From June 2006 to December 2008 a dataset of 94
events with local magnitude range from 0.7 to 5.1 has been collected. An ad hoc data-processing system have been created in
order to provide, after each recorded event, engineering parameters such as peak ground acceleration (PGA) and velocity (PGV),
response spectra (SA and PSV), Arias and Housner intensities. Data dissemination is achieved through the web site , while the waveforms are distributed through the Italian strong motion database (). 相似文献
47.
D. Bindi M. Massa L. Luzi G. Ameri F. Pacor R. Puglia P. Augliera 《Bulletin of Earthquake Engineering》2014,12(1):431-448
48.
I. V. Pekov N. V. Chukanov N. N. Kononkova O. V. Yakubovich W. Massa A. V. Voloshin 《Geology of Ore Deposits》2009,51(7):595-607
Tveitite-(Y) as pods up to 10 cm across has been found at Mt. Rovgora, the Western Keivy, Kola Peninsula, Russia, in an albite-quartz-amazonite pegmatite vein related to alkaline granite. Tveitite-(Y) grains (up to 4 cm) are parallel microintergrowths of two isostructural varieties, Ca9.5Na1.7Y5.2Ln2.0F42.6 and Ca11.4Na1.9Y4.4Ln1.4F42.0. The idealized structural formula (Z = 3) is (Y, Na)6(Ca, LREE)6(Ca, Na, HREE)6(Ca, Na)F42; the simplified formula is (Ca, REE, Na)13(Y, Na)6F42; space group R \(\bar 3\) a = 17.020, c = 9.679 Å. [Lanthanoides are abbreviated in this paper as Ln, whereas Ln + Y as REE]. Nine fluorite samples containing from 0 to 18 mol % (REE)F3 were examined by electron microprobe, X-ray powder diffraction, and IR spectroscopy. The crystal structure of natural yttrofluorite has been determined for the first time (R aniso = 1.47 %): Fm3m, a = 5.493 Å; the structural formula is (Ca0.82Y0.12Ln0.06)F2.15. Earlier published and new data show that yttrofluorite containing (REE)F3 > 20 mol % and REE-enriched fluorite with LREE > Y (HREE) are metastable under room conditions. In nature, tveitite-(Y) is a product of solid-state transformation of metastable yttrofluorite with (REE)F3 > 20 mol %. Inferred protophases could have been exsolved into tveitite-(Y) variable in composition or tveitite-(Y) + yttrofluorite stable under normal conditions. The formation of tveitite-(Y) requires the erichment of a protophase not only in Y but also in LREE and HREE as stabilizing admixtures regularly distributed by different types of Ca-dominant structural sites. Tveitite-(Y) and yttrofluorite are geochemical indicators of a medium that is not only enriched in Y, Ln, and F, but also depleted in Na, Ca, CO2 and P. 相似文献
49.
G. Di Giulio S. Marzorati F. Bergamaschi P. Bordoni F. Cara E. D��Alema C. Ladina M. Massa 《Bulletin of Earthquake Engineering》2011,9(3):783-807
The 2009 Mw 6.3 L’Aquila event caused extensive damage in the city of L’Aquila and in some small towns in its vicinity. The
most severe damage was recognized SE of L’Aquila town along the Aterno river valley. Although building vulnerability and near-source
effects are strongly responsible for the high level of destruction, site effects have been invoked to explain the damage heterogeneities
and the similarities between the 2009 macroseismic field with the intensities of historical earthquakes. The small village
of Onna is settled on quaternary alluvium and suffered during the L’Aquila event an extremely heavy damage in the masonry
structures with intensity IX–X on the Mercalli-Cancani-Sieberg (MCS) scale. The village of Monticchio, far less than 1.3 km
from Onna, is mostly situated on Mesozoic limestone and suffered a smaller level of damaging (VI MCS). In the present paper,
we analyze the aftershock recordings at seismic stations deployed in a small area of the middle-Aterno valley including Onna
and Monticchio. The aim is to investigate local amplification effects caused by the near-surface geology. Because the seismological
stations are close together, vulnerability and near-source effects are assumed to be constant. The waveform analysis shows
that the ground motion at Onna is systematically characterized by large high-frequency content. The frequency resonance is
varying from 2 to 3 Hz and it is related to alluvial sediments with a thickness of about 40 m that overlay a stiffer Pleistocene
substrate. The ground motion recordings of Onna are well reproduced by the predictive equation for the Italian territory. 相似文献
50.
Corrado Massa 《Astrophysics and Space Science》2002,282(3):471-475
The existence of the universal quantization law E=n ε E =any energy; n = an integer, ε = the fundamental energy ∼ħ c/R with ħ = the reduced Planck constant, c = the speed of light, R = the curvature radius of the closed cosmological space) is advocated and discussed. A possible connection between ε and
the mass of elementary particles is pointed out. 相似文献