To enhance the service life and application range of titanium alloys in the aerospace sector, Ti-Zr-B-C coatings with varying B4C contents (0–30 wt%) on TC11 titanium alloy was fabricated by laser ...cladding. The microstructure and anti-ablation were investigated in the present work. The results show that the whisker-like TiB phases and granular TiC and ZrC phases were observed in the coatings due to the in-situ reactions. With increasing the content of B4C, the number of reinforcing phases in the coating increased and distributed uniformly, resulting in the improvement of the microhardness up to 803.8HV. Furthermore, due to the formation of TiO2-ZrO2-B2O3 dense multiphase oxide layer on the surface during the ablation process, the coating with 20 wt% B4C exhibited the best anti-ablation at 1400ºC, the mass ablation rate (MAR) and linear ablation rate (LAR) were −2.62 mg/s and 3.67μm/s, respectively, which were just 62.8 % and 50.07 % in comparison with the substrate. This is mainly attributed to the formation of TiO2-ZrO2-B2O3 layer is beneficial to reduce the infiltration of O2 and the evaporation of liquid B2O3, leading to the excellent anti-ablation.
•The TiB, TiC and ZrC reinforcing phases were in-situ formed in the Ti-Zr-B-C coating via laser cladding.•With increasing the content of B4C, the microhardness of the coating increased gradually.•The coating with 20wt% B4C exhibited the best anti-ablation among all the coatings.
A
bstract
By using 6.32 fb
−
1
of data collected with the BESIII detector at center-of-mass energies between 4.178 and 4.226 GeV, we perform an amplitude analysis of the decay
D
s
+
→
K
S
0
π
+
π
0
...and determine the relative fractions and phase differences of different intermediate processes, which include
K
S
0
ρ
(770)
+
,
K
S
0
ρ
(1450)
+
,
K
*
(892)
0
π
+
,
K
*
(892)
+
π
0
, and
K
*
(1410)
0
π
+
. With the detection efficiency based on the amplitude analysis results, the absolute branching fraction is measured to be
ℬ
D
s
+
→
K
S
0
π
+
π
0
=
5.43
±
0.30
stat
±
0.15
syst
×
10
−
3
.
Evaluating the construction effectiveness of active distribution network is the key point of coordinated development of distribution network. At present, effectiveness evaluation on the distribution ...network in domestic only focuses on output performance while leaves out of consideration of utilization efficiency of investment. Therefore, this paper presents a kind of effectiveness evaluation method for construction and updating of the active distribution network based on public service value model which could make an overall evaluation in two dimensions of output performance and cost efficiency. The evaluation results are comprehensively analyzed on the four quadrant diagram, and the evaluation conclusions and suggestions are put forward according to the quadrant of the evaluation objects. Finally, it verifies this evaluation method is scientific, reasonable and feasible in guiding construction investment of the power grid by applying the method in evaluating construction effectiveness of distribution networks in some areas of Hubei Province in China.
Based on a sample of 1.31×109 J/ψ events collected with the BESIII detector, the matrix elements for the decays η′→ηπ+π− and η′→ηπ0π0 are determined using 351,016 η′→(η→γγ)π+π− and 56,249 ...η′→(η→γγ)π0π0 events with background levels less than 1%. Two commonly used representations are used to describe the Dalitz plot density. We find that an assumption of a linear amplitude does not describe the data well. A small deviation of the obtained matrix elements between η′→ηπ+π− and η′→ηπ0π0 is probably caused by the mass difference between charged and neutral pions or radiative corrections. No cusp structure in η′→ηπ0π0 is observed.
High Mountain Asia (HMA) is the headwater area for major Asian rivers, providing a vast amount of freshwater to billions of people in Asia. These rivers also make their surrounding areas highly ...vulnerable to destructive water‐related disasters. However, the complex spatiotemporal variability of runoff over HMA and its underlying mechanisms are poorly understood. This study investigates into the spatial heterogeneity of HMA's runoff variability at three timescales (interannual, interdecadal, and multidecadal) and the roles played by climate conditions and catchment properties. We find significant interannual and multidecadal variability of runoff in west and central HMA, and significant interdecadal variability in central and east HMA. At interannual and multidecadal timescales, the runoff variability tends to be more significant in dryer basins. The variability of runoff at the three timescales is largely controlled by climate variations, especially precipitation. The catchment properties, including groundwater storage and glacier‐snow meltwater, also play important roles in regulating the effect of precipitation. In particular, the high contributions of glacier‐snow meltwater in east HMA can weaken the response of runoff variability to precipitation at interannual and multidecadal timescales. The space‐time patterns of runoff variability over HMA are driven by atmospheric drivers including El Niño‐Southern Oscillation, Interdecadal Pacific Oscillation, and Atlantic Multidecadal Oscillation across timescales. The results of this study provide a better understanding of HMA's runoff variability and its physical mechanisms, which have critical implications for sustainable freshwater management and effective risk mitigation in this densely populated and ecologically vulnerable region.
Key Points
Significant runoff variability at interannual and multidecadal timescales is detected in west and central High Mountain Asia (HMA)
HMA's runoff variability is primarily controlled by precipitation, while catchment properties regulate precipitation effect in diverse ways
Spatiotemporal variability in HMA's runoff is modulated by large‐scale atmospheric drivers including El Niño‐Southern Oscillation, Interdecadal Pacific Oscillation, and Atlantic Multidecadal Oscillation
By analyzing 482 pb−1 of e+e− collision data collected at the center-of-mass energy s=4.009 GeV with the BESIII detector, we measure the branching fractions for the semi-leptonic decays Ds+→ϕe+νe, ...ϕμ+νμ, ημ+νμ and η′μ+νμ to be B(Ds+→ϕe+νe)=(2.26±0.45±0.09)%, B(Ds+→ϕμ+νμ)=(1.94±0.53±0.09)%, B(Ds+→ημ+νμ)=(2.42±0.46±0.11)% and B(Ds+→η′μ+νμ)=(1.06±0.54±0.07)%, where the first and second uncertainties are statistical and systematic, respectively. The branching fractions for the three semi-muonic decays Ds+→ϕμ+νμ,ημ+νμ and η′μ+νμ are determined for the first time and that of Ds+→ϕe+νe is consistent with the world average value within uncertainties.
Search for the decay hc→ π0J/ψ Ban, Y.; Boyko, I.; Cai, X. ...
The journal of high energy physics,
05/2022, Letnik:
2022, Številka:
5
Journal Article
Recenzirano
Odprti dostop
A
bstract
A search for the decay
h
c
→ π
0
J/ψ
is performed using a sample of
hc
produced in the reaction
e
+
e
−
→ π
+
π
−
h
c
. The data samples were collected with the BESIII detector at ...center-of-mass energies between 4.189 and 4.437 GeV, corresponding to a total integrated luminosity of 11 fb
−
1
. No significant signal is observed. Upper limits on the branching ratio
B
(
h
c
→ π
0
J/ψ
)
/
B
(
h
c
→ γη
c
→ γK
+
K
−
π
0
) and on the branching fraction
B
(
h
c
→ π
0
J/ψ
) are determined to be 7
.
5
×
10
−
2
and 4
.
7
×
10
−
4
at 90% confidence level, respectively. The latter is derived from the former using the measured branching fraction of the normalization channel. This is the first determination of the upper limit of the decay
h
c
→ π
0
J/ψ
.
A diamond-shaped P-doped ZnO nanostructure was fabricated on a Si (100) substrate by a chemical vapor deposition method. The photoluminescence properties of the ZnO nanostructure were studied with a ...temperature range from 81 to 306 K. At 81 K, a series of transitions of donor−acceptor pairs and their phonon replicas were observed in the PL spectrum. These results revealed that shallow-donor and deep-acceptor impurity bands existed in the P-doped ZnO nanostructure. From 81 to 111 K, the abnormal UV emission intensity was observed. The multiphonon scattering spectra were attributed to the interaction of electrons and phonons.
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