427,335 research outputs found
Precision measurement of the B[0 over s]–[– over B][0 over s] oscillation frequency with the decay B[0 over s]→D[– over s]π[superscript +]
No full textA key ingredient to searches for physics beyond the Standard Model in B[0 over s] mixing phenomena is the measurement of the B[0 over s]–[– over B][0 over s] oscillation frequency, which is equivalent to the mass difference Δm[subscript s] of the B[0 over s] mass eigenstates. Using the world's largest B[0 over s] meson sample accumulated in a dataset, corresponding to an integrated luminosity of 1.0 fb[superscript −1], collected by the LHCb experiment at the CERN LHC in 2011, a measurement of Δm[subscript s] is presented. A total of about 34 000 B[0 over s] → D[− over s]π[superscript +] signal decays are reconstructed, with an average decay time resolution of 44 fs. The oscillation frequency is measured to be Δm[subscript s] = 17.768 ± 0.023 (stat) ± 0.006 (syst) ps[superscript −1], which is the most precise measurement to date.National Science Foundation (U.S.
A molecular dynamics study of N-A-S-H gel with various Si/Al ratios
No full textThe understanding of sodium aluminosilicate hydrate (N-A-S-H) gel is still limited due to its complex and amorphous structure. Recently, molecular dynamics simulation has provided a unique opportunity to better understand the structure of N-A-S-H gel from nanoscale. In this work, the N-A-S-H gel structure was obtained by simulating the polymerization of Si and Al monomers by molecular dynamics. The simulated polymerization process is in good agreement with the experimental results especially in terms of the reaction rate of Si and Al species. The atomic structural features of the N-A-S-H gel were analyzed in terms of bond length and bond angle information, simulated X-ray diffraction (XRD) and Qn distribution. A significant finding is the existence of pentacoordinate Al in all simulated N-A-S-H structures, indicating that pentacoordinate Al in geopolymer does not only come from raw material. Besides, the results show that a smaller Si/Al ratio led to a more crosslinked and compacted structure of N-A-S-H gel
Electricity supply technology for a steam power plant in Mokha City, Yemen [mini review]
No full textThis mini review evaluates the potential of electricity supply technology for a steam power station in Mokha City,
Yemen. It examines the current energy crisis, highlighting the significant gap between demand and supply. The report discusses
the benefits of modern steam power technologies, including reliability, scalability, and the potential for renewable integration.
Key challenges such as infrastructure limitations, operational costs, and political instability are also addressed. The findings
suggest that strategic investments and training are essential for enhancing energy security in the region
Study of acidic degradation of alkali-activated materials using synthetic C-(N)-A-S-H and N-A-S-H gels
No full textAlkali-activated materials (AAMs) are usually recognized having better acid resistance compared to ordinary Portland cement (OPC), however, the detailed mechanism has not been well studied due to the complexity of raw materials and hardened matrix. In this study, two typical binding gels in AAMs, sodium aluminum silicate hydrate (N-A-S-H) and calcium (sodium) aluminum silicate hydrate (C-(N)-A-S-H), were chemically prepared by laboratory synthesized aluminosilicate powders. The microstructure and composition evolution of the two gels exposed to sulfuric acid were investigated. The results showed that the C-(N)-A-S-H gel had higher degree of structural order than the N-A-S-H gel, while the N-A-S-H gel showed higher polymerization. The AlIV in N-A-S-H gel transferred completely to AlV during sulfuric acid attack, while trace amount of AlIV was still detected in the exposed C-(N)-A-S-H gels. Both gels had increased silica polymerization degree after exposure to sulfuric acid solution. Due to rapider dealumination of N-A-S-H gel than C-(N)-A-S-H gel, the Si/Al ratio increased much higher in the former. The molecular framework changes of N-A-S-H gel caused by dealumination was found to have less effect on the integrity though than that of C-(N)-A-S-H gel, in which coarse gypsum crystalline grains formed and led to destructive stress in hardened matrix. This paper provides an insight at microstructure level of the two typical gels, which is essential for the manufacturing and application of alkali-activated materials
Intrinsic sulfuric acid resistance of C-(N)-A-S-H and N-A-S-H gels produced by alkali-activation of synthetic calcium aluminosilicate precursors
No full textThis study investigates the decomposition of alkali-activated materials (AAMs) in sulfuric acid solution. Four sodium-containing calcium aluminium-substituted silicate hydrate (C-(N)-A-S-H) and aluminosilicate hydrate (N-A-S-H) gels with designed Ca/Si and Si/Al ratios are produced with synthetic calcium aluminosilicate powders. The formation of additional calcium products in Ca-rich and Al-sufficient sample is likely helpful to retard the attack of sulfuric acid on the C-(N)-A-S-H/N-A-S-H gels. The Sisingle bondO bond strength of N-A-S-H gel appears weaker than that of C-(N)-A-S-H gel. The calcium in the gels prevents the leaching of silicon from gels. The length of silicon chains in the C-(N)-A-S-H gel increases with increased Si/Al ratio while exposure to acid solution. The chain length of the N-A-S-H gel increases with reduced Si/Al ratio. C-(N)-A-S-H gels show a higher resistance to leaching than N-A-S-H gel, while the latter has a high resistance to depolymerization under acid attack. This study provides a basic route to understand the effect of AAMs composition on acid resistance
Diffusive author(s), cohesive author: Analysis of S/N (1994)
No full textThis study indicates the ways in which various aspects of the author(s) are brought forth in Dumb type’s performance art, the S/N production. Previous research has suggested a non-hierarchical organization of Dumb type and the absence of a “privileged author” in Dumb type’s collaborative work, S/N. However, the results that I have investigated from member’s interviews on the creative process of S/N along with my analysis of the recorded images of S/N, indicate a different aspect of the author(s). First, S/N was created through, so to speak, the collective ideas of the members of Dumb type. Further, S/N has at least nine quotations from previous performances, installations, and printed writings, besides the work-in-progress technique. Explicating one of the “author functions” as given by Michel Foucault, each text has plural subjects of the author. However, it has been revealed from members’ interviews that Teiji Furuhashi had a decision-making role in selecting the members’ ideas within the performance. Since then, S/N has had plural subjects of creation; however, Furuhashi is one of the subjects of creation along with the “privileged author.” S/N has plural authors (diffusive authors) yet at the same time, it has a “privileged author,” Teiji Furuhashi (cohesive author)
Observations of Bºs→ψ(2S)η and Bº(s)→ψ(2S)π+π- decays
No full textFirst observations of the B0s
→ψ(2S)η, B0 →ψ(2S)π
+
π
− and B0s
→ψ(2S)π
+
π
− decays are made
using a dataset corresponding to an integrated luminosity of 1.0 fb−1 collected by the LHCb experiment in
proton–proton collisions at a centre-of-mass energy of
√
s = 7 TeV. The ratios of the branching fractions
of each of the ψ(2S) modes with respect to the corresponding J/ψ decays are
B(B0s
→ψ(2S)η)
÷
B(B0s
→J/ψη)
= 0.83± 0.14 (stat)±0.12 (syst) ±0.02 (B),
;
B(B0→ψ(2S)π
+
π
−
)
÷
B(B0→J/ψπ
+
π
−
)
= 0.56± 0.07 (stat)±0.05 (syst)± 0.01 (B),
;
B(B0s
→ψ(2S)π
+
π
−
)
÷
B(B0s
→J/ψπ
+
π
−
)
= 0.34± 0.04 (stat)±0.03 (syst)± 0.01 (B),
where the third uncertainty corresponds to the uncertainties of the dilepton branching fractions of the J/ψ
and ψ(2S) meson decays
Measurement of prompt hadron production ratios in collisions at 0.9 and 7 TeV
No full textThe charged-particle production ratios pˉ/p , K −/K +, π −/π +, (p+pˉ)/(π++π−) , (K ++K −)/(π ++π −) and (p+pˉ)/(K++K−) are measured with the LHCb detector using 0.3 nb−1 of pp collisions delivered by the LHC at s√=0.9 TeV and 1.8 nb−1 at s√=7 TeV . The measurements are performed as a function of transverse momentum p T and pseudorapidity η. The production ratios are compared to the predictions of several Monte Carlo generator settings, none of which are able to describe adequately all observables. The ratio pˉ/p is also considered as a function of rapidity loss, Δy≡y beam−y, and is used to constrain models of baryon transport
RRS James Cook Cruise 30, 26 Dec 2008-30 Jan 2009. Antarctic Deep Water Rates of Export (ANDREX)
No full textThis report describes scientific activities on RRS James Cook cruise 30, “ANDREX”, westwards from 30°E and in the vicinity of latitude 60°S, between late December 2008 and late January 2009. The cruise was terminated about halfway through by a medical emergency. Hydrographic work comprised 27 CTD/LADCP stations. Water samples were captured for measurement of salinity, dissolved oxygen, inorganic nutrients, oxygen isotope fraction, chlorofluorocarbons and sulphur hexafluoride, dissolved inorganic carbon and alkalinity, helium / tritium / noble gases and radiocarbon. Underway measurements comprised navigation, currents (ADCP), meteorology, and sea surface temperature and salinity. The remainder of the hydrographic section was executed a year later on RRS James Clark Ross, cruise JR239
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