•The application of nanofluids for cooling electronic devices is analyzed.•Nanofluids as heat transfer fluids improve thermal performance of heat exchangers.•The most used nanoparticles in this field ...are Al2O3.•In literature, there are no data about the problem of clogging and how to face it.
Cooling of electronic devices is one of the main challenge of new generation technology. The extreme miniaturization has high benefits, but the heat to be dissipated per unit of surface increases in uncontrolled way. In this paper the application of a new generation of heat transfer fluids, nanofluids, to electronic devices is analyzed. Even if the use of nanofluids is not still common, there are many papers that deal with this topic, reporting both experimental and theoretical results. The development of this technology could be one of the key elements that could give an important impulse to further miniaturization of electronic devices and at the same time increase their energy efficiency.
We reassess the impact of short-distance constraints for the longitudinal component of the hadronic light-by-light amplitude on the anomalous magnetic moment of the muon,
a
μ
=
(
g
-
2
)
μ
/
2
, by ...comparing different solutions that have recently appeared in the literature. In particular, we analyze the relevance of the exact axial anomaly and its impact on
a
μ
and conclude that it remains rather limited. We show that all recently proposed solutions agree well within uncertainties on the numerical estimate of the impact of short-distance constraints on
a
μ
, despite differences in the concrete implementation. We also take into account the recently calculated perturbative corrections to the massless quark loop to update our estimate and outline the path towards future improvements.
A
bstract
Based on dispersion theory, we present a formalism for a model-independent evaluation of the hadronic light-by-light contribution to the anomalous magnetic moment of the muon. In ...particular, we comment on the definition of the pion pole in this framework and provide a master formula that relates the effect from
ππ
intermediate states to the partial waves for the process
γ
*
γ
*
→ ππ
. All contributions are expressed in terms of on-shell form factors and scattering amplitudes, and as such amenable to an experimental determination.
This work deals with the efficiency and the energy behavior of Ground Source Heat Pumps (GSHPs) used for heating and cooling of buildings. In particular horizontal type heat exchangers have been ...investigated for different configurations, in order to evaluate the characteristics of these systems in the most common layouts and in different working conditions. The main results pointed out the heat fluxes transferred to and from the ground and the efficiency of the system. The calculations were made with the CFD code Fluent and the simulations covered one year of system operation, both in summer and winter for typical climate conditions of the South of Italy. The most important parameter for the heat transfer performance of the system resulted the thermal conductivity of the ground around the heat exchanger and the optimal ground type was that with the highest thermal conductivity (3 W/m K in the cases analyzed in this work). The choice of the velocity of the heat transfer fluid inside the tubes was another key factor. The depth of installation of the horizontal ground heat exchangers did not play an important role on the system performance. The helical heat exchanger arrangement resulted as the best performing one.
In this paper, we discuss how windows in Euclidean time can be used to isolate the origin of potential conflicts between evaluations of the hadronic-vacuum-polarization (HVP) contribution to the ...anomalous magnetic moment of the muon in lattice QCD and from e+e−→hadrons cross-section data. We provide phenomenological comparison numbers evaluated from e+e−→hadrons data for the window quantities most commonly studied in lattice QCD, complete with the correlations among them. We discuss and evaluate modifications of window parameters that could be useful in dissecting the energy dependence of tensions in the HVP integral and emphasize that further optimizations require a precise knowledge of the full covariance matrix in lattice-QCD calculations as well.
We review lattice results related to pion, kaon, D- and B-meson physics with the aim of making them easily accessible to the particle-physics community. More specifically, we report on the ...determination of the light-quark masses, the form factor \f_+(0)\, arising in the semileptonic \K \rightarrow \pi \ transition at zero momentum transfer, as well as the decay constant ratio \f_K/f_\pi \ and its consequences for the CKM matrix elements \V_{us}\ and \V_{ud}\. Furthermore, we describe the results obtained on the lattice for some of the low-energy constants of \SU(2)_L\times SU(2)_R\ and \SU(3)_L\times SU(3)_R\ Chiral Perturbation Theory. We review the determination of the \B_K\ parameter of neutral kaon mixing as well as the additional four B parameters that arise in theories of physics beyond the Standard Model. The latter quantities are an addition compared to the previous review. For the heavy-quark sector, we provide results for \m_c\ and \m_b\ (also new compared to the previous review), as well as those for D- and B-meson-decay constants, form factors, and mixing parameters. These are the heavy-quark quantities most relevant for the determination of CKM matrix elements and the global CKM unitarity-triangle fit. Finally, we review the status of lattice determinations of the strong coupling constant \\alpha _s\.
The urban heat island (UHI) of Milan (Italy) was analyzed by means of an Energy Balance Model calibrated for four different sites representative of an urban park, the UHI plateau and the UHI peak of ...the selected town. The model was driven by weather stations data and parameterized as a function of land use, urban morphology, human activities and soil hydrology. A run of the model on the 1981–2014 period was carried out on four hourly datasets. Results provided useful statistics of energy balance terms and the climate risk of extreme thermal events (sensible heat fraction of the total turbulent flux H% exceeding specific thresholds). Results for summer (June–August trimester) show that the mitigation of climate risk of high values of H% given by the urban park is more effective for June than for July and August. We also discuss the relevance of enhanced soil water reservoirs in urban green areas to improve the mitigating effect of urban vegetation on UHI by both the substitution of sensible heat fluxes with latent heat ones and the increase of the shading effect of tree canopies.
Display omitted
•A surface energy balance (SEB) was applied to model the urban heat island of Milan•Three different levels of UHI impact were considered (urban park, urban plateau, urban peak)•Three different levels of green management were considered•The maximum mitigation of UHI was provided by tree shade but irrigation is also effective.•The SEB approach provide support to evaluate the effect of wide set alternative urban design and green management options.
FLAG Review 2019 Aoki, S.; Aoki, Y.; Bečirević, D. ...
The European physical journal. C, Particles and fields,
02/2020, Volume:
80, Issue:
2
Journal Article
Peer reviewed
Open access
We review lattice results related to pion, kaon,
D
-meson,
B
-meson, and nucleon physics with the aim of making them easily accessible to the nuclear and particle physics communities. More ...specifically, we report on the determination of the light-quark masses, the form factor
f
+
(
0
)
arising in the semileptonic
K
→
π
transition at zero momentum transfer, as well as the decay constant ratio
f
K
/
f
π
and its consequences for the CKM matrix elements
V
us
and
V
ud
. Furthermore, we describe the results obtained on the lattice for some of the low-energy constants of
S
U
(
2
)
L
×
S
U
(
2
)
R
and
S
U
(
3
)
L
×
S
U
(
3
)
R
Chiral Perturbation Theory. We review the determination of the
B
K
parameter of neutral kaon mixing as well as the additional four
B
parameters that arise in theories of physics beyond the Standard Model. For the heavy-quark sector, we provide results for
m
c
and
m
b
as well as those for
D
- and
B
-meson decay constants, form factors, and mixing parameters. These are the heavy-quark quantities most relevant for the determination of CKM matrix elements and the global CKM unitarity-triangle fit. We review the status of lattice determinations of the strong coupling constant
α
s
. Finally, in this review we have added a new section reviewing results for nucleon matrix elements of the axial, scalar and tensor bilinears, both isovector and flavor diagonal.
We demonstrate that near the threshold, the pi pi scattering amplitude contains a pole with the quantum numbers of the vacuum--commonly referred to as the sigma--and determine its mass and width ...within small uncertainties. Our derivation does not involve models or parametrizations but relies on a straightforward calculation based on the Roy equation for the isoscalar S wave.
FLAG Review 2019 Aoki, S; Aoki, Y; Bečirević, D ...
The European physical journal. C, Particles and fields,
02/2020, Volume:
80, Issue:
2
Journal Article
Peer reviewed
Open access
We review lattice results related to pion, kaon, D-meson, B-meson, and nucleon physics with the aim of making them easily accessible to the nuclear and particle physics communities. More ...specifically, we report on the determination of the light-quark masses, the form factor f+(0) arising in the semileptonic K→π transition at zero momentum transfer, as well as the decay constant ratio fK/fπ and its consequences for the CKM matrix elements Vus and Vud. Furthermore, we describe the results obtained on the lattice for some of the low-energy constants of SU(2)L×SU(2)R and SU(3)L×SU(3)R Chiral Perturbation Theory. We review the determination of the BK parameter of neutral kaon mixing as well as the additional four B parameters that arise in theories of physics beyond the Standard Model. For the heavy-quark sector, we provide results for mc and mb as well as those for D- and B-meson decay constants, form factors, and mixing parameters. These are the heavy-quark quantities most relevant for the determination of CKM matrix elements and the global CKM unitarity-triangle fit. We review the status of lattice determinations of the strong coupling constant αs. Finally, in this review we have added a new section reviewing results for nucleon matrix elements of the axial, scalar and tensor bilinears, both isovector and flavor diagonal.
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