6,959 research outputs found
Sistemi di propulsione elettrotermica
Si pongono ill risalto le liniitazioni della propulsionechimica rispetto a quella terinica non eonvenzionale e si esaniinano i problemie le applicazioni dei sistemi elettrotermiei. Si illustrano alcune proposte permigliorare il processo di riassociazione aH'interno deH'ugello in presenza difenomeni di non-equilibrio chimico
Effects of Marangoni numbers on thermocapillary drop migration: constant for quasi-steady state?
The overall {\it steady}-state energy balance with two phases in a flow
domain requires that the change in energy of the domain is equal to the
difference between the total energy entering the domain and that leaving the
domain. From the condition, the integral thermal flux across the surface is
studied for a {\it steady} thermocapillary drop migration in a flow field with
uniform temperature gradient at small and large Marangoni (Reynolds) numbers.
The drop is assumed to have only a slight axisymmetric deformation from a
sphere. It is identified that a conservative/nonconservative integral thermal
flux across the surface in the {\it steady} thermocapillary drop migration at
small/large Marangoni (Reynolds) numbers. The conservative flux confirms the
assumption of {\it quasi-steady} state in the thermocapillary drop migration at
small Marangoni (Reynolds) numbers. The nonconservative flux may well result
from the invalid assumption of {\it quasi-steady} state, which indicates that
the thermocapillary drop migration at large Marangoni (Reynolds) numbers cannot
reach {\it steady} state and is thus a {\it unsteady} process.Comment: 21 pages. arXiv admin note: text overlap with arXiv:1112.276
Adiabatic Evolution for Systems with Infinitely many Eigenvalue Crossings
We formulate an adiabatic theorem adapted to models that present an
instantaneous eigenvalue experiencing an infinite number of crossings with the
rest of the spectrum. We give an upper bound on the leading correction terms
with respect to the adiabatic limit. The result requires only differentiability
of the considered spectral projector, and some geometric hypothesis on the
local behaviour of the eigenvalues at the crossings
Monitoring urban heat island through google earth engine. Potentialities and difficulties in different cities of the United States
The aim of this work is to exploit the large-scale analysis capabilities of the innovative Google Earth Engine platform in order to investigate the temporal variations of the Urban Heat Island phenomenon as a whole. A intuitive methodology implementing a large-scale correlation analysis between the Land Surface Temperature and Land Cover alterations was thus developed. The results obtained for the Phoenix MA are promising and show how the urbanization heavily affects the magnitude of the UHI effects with significant increases in LST. The proposed methodology is therefore able to efficiently monitor the UHI phenomenon
Intramyocardial hemorrhage: An enigma for cardiac MRI?
Cardiovascular magnetic resonance (CMR) is a useful noninvasive technique for determining the presence of microvascular obstruction (MVO) and intramyocardial hemorrhage (IMH), frequently occurring in patients after reperfused myocardial infarction (MI). MVO, or the so-called no-reflow phenomenon, is associated with adverse ventricular remodeling and a poor prognosis during follow-up. Similarly, IMH is considered a severe damage after revascularization by percutaneous primary coronary intervention (PPCI) or fibrinolysis, which represents a worse prognosis. However, the pathophysiology of IMH is not fully understood and imaging modalities might help to better understand that phenomenon. While, during the past decade, several studies examined the distribution patterns of late gadolinium enhancement with different CMR sequences, the standardized CMR protocol for assessment of IMH is not yet well established. The aim of this review is to evaluate the available literature on this issue, with particular regard to CMR sequences. New techniques, such as positron emission tomography/magnetic resonance imaging (PET/MRI), could be useful tools to explore molecular mechanisms of the myocardial infarction healing process
Extremal curves in nilpotent Lie groups
We classify extremal curves in free nilpotent Lie groups. The classification
is obtained via an explicit integration of the adjoint equation in Pontryagin
Maximum Principle. It turns out that abnormal extremals are precisely the
horizontal curves contained in algebraic varieties of a specific type. We also
extend the results to the nonfree case.Comment: 30 pages, final versio
Étude du Chrome Comme Liaison Métallique Antidiffusante Entre Uranium et Aluminium. EUR 413. = Study of Chrome as an Antidiffusing Metal Bond between Uranium and Aluminum. EUR 413.
Temporal dynamics of ‘Ca. Phytoplasma mali’ load in the insect vector Cacopsylla melanoneura
- …