Engineering topics
Hu, T.
Publications and source records attributed to Hu, T..
Study of e + e − → ω χ c J at Center of Mass Energies from 4.21 to 4.42 GeV
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Search for the Y ( 4140 ) via e + e − → γ ϕ J / ψ at s = 4.23 , 4.26 and 4.36 GeV
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Observation of e + e − → π 0 π 0 h c and a Neutral Charmoniumlike Structure Z c ( 4020 ) 0
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Independent measurement of the neutrino mixing angle θ 13 via neutron capture on hydrogen at Daya Bay
A new measurement of the θ 13 mixing angle has been obtained at the Daya Bay Reactor Neutrino Experiment via the detection of inverse beta decays tagged by neutron capture on hydrogen. The antineutrino events for hydrogen capture are distinct from those for gadolinium capture with largely different systematic uncertainties, allowing a determination independent of the gadolinium-capture result and an improvement on the precision of the θ 13 measurement. With a 217-day antineutrino data set obtained with six antineutrino detectors and from six 2.9 GW th reactors, the rate deficit observed at the far hall is interpreted as sin 2 2θ 13 =0.083±0.018 in the three-flavor oscillation model. When combined with the gadolinium-capture result from Daya Bay, we obtain sin 2 2θ 13 =0.089±0.008 as the final result for the six-antineutrino-detector configuration of the Daya Bay experiment.
Search for a Light Sterile Neutrino at Daya Bay
In this study, a search for light sterile neutrino mixing was performed with the first 217 days of data from the Daya Bay Reactor Antineutrino Experiment. The experiment’s unique configuration of multiple baselines from six 2.9 GW th nuclear reactors to six antineutrino detectors deployed in two near (effective baselines 512 m and 561 m) and one far (1579 m) underground experimental halls makes it possible to test for oscillations to a fourth (sterile) neutrino in the 10 - 3 eV 2 < | Δ m 41 2 | < 0.3 eV 2 range. The relative spectral distortion due to the disappearance of electron antineutrinos was found to be consistent with that of the three-flavor oscillation model. The derived limits on sin 2 2 θ 14 cover the 10 - 3 eV 2 ≲ | Δ m 41 2 | ≲ 0.1 eV 2 region, which was largely unexplored.
Study of e + e - → p p ¯ π 0 in the vicinity of the ψ ( 3770 )
The process e + e - →pp¯π 0 has been studied by analyzing data collected at √s=3.773 GeV, at s√=3.650 GeV, and during a ψ(3770) line shape scan with the BESIII detector at the BEPCII collider. The Born cross section of pp¯π 0 in the vicinity of the ψ(3770) is measured, and the Born cross section of ψ(3770)→pp¯π 0 is extracted considering interference between resonant and continuum production amplitudes. Two solutions with the same probability and a significance of 1.5σ are found. The solutions for the Born cross section of ψ(3770)→pp¯π 0 are 33.8±1.8±2.1 pb and 0.06 +0.10 -0.04 +0.01 -0.01 pb (<0.22 pb at a 90% confidence level). Using the estimated cross section and a constant decay amplitude approximation, the cross section σ(pp¯→ψ(3770)π 0 ) is calculated for the kinematic situation of the planned P¯ANDA experiment. The maximum cross section corresponding to the two solutions is expected to be less than 0.79 nb at 90% confidence level and 122±10 nb at a center-of-mass energy of 5.26 GeV.
Measurement of the D → K − π + strong phase difference in ψ ( 3770 ) → D 0 D ¯ 0
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Measurement of transient atomic displacements in thin films with picosecond and femtometer resolution
We report measurements of the transient structural response of weakly photo-excited thin films of BiFeO 3 , Pb(Zr,Ti)O 3 , and Bi and time-scales for interfacial thermal transport. Utilizing picosecond x-ray diffraction at a 1.28 MHz repetition rate with time resolution extending down to 15 ps, transient changes in the diffraction angle are recorded. These changes are associated with photo-induced lattice strains within nanolayer thin films, resolved at the part-per-million level, corresponding to a shift in the scattering angle three orders of magnitude smaller than the rocking curve width and changes in the interlayer lattice spacing of fractions of a femtometer. The combination of high brightness, repetition rate, and stability of the synchrotron, in conjunction with high time resolution, represents a novel means to probe atomic-scale, near-equilibrium dynamics.
Spectral Measurement of Electron Antineutrino Oscillation Amplitude and Frequency at Daya Bay
A measurement of the energy dependence of antineutrino disappearance at the Daya Bay reactor neutrino experiment is reported. Electron antineutrinos ( ν ¯ e ) from six 2.9 GW th reactors were detected with six detectors deployed in two near (effective baselines 512 and 561 m) and one far (1579 m) underground experimental halls. Using 217 days of data, 41 589 (203 809 and 92 912) antineutrino candidates were detected in the far hall (near halls). An improved measurement of the oscillation amplitude sin 2 2 θ 13 = 0.09 0 - 0.009 + 0.008 and the first direct measurement of the ν ¯ e mass-squared difference | Δ m e e 2 | = ( 2.5 9 - 0.20 + 0.19 ) × 10 - 3 e V 2 is obtained using the observed ν ¯ e rates and energy spectra in a three-neutrino framework. This value of | Δ m e e 2 | is consistent with | Δ m μ μ 2 | measured by muon neutrino disappearance, supporting the three-flavor oscillation model.
Application of fracture mechanics on the Space Shuttle
During the design stages of the shuttle orbiter, fracture-mechanics concepts were applied extensively to the highly stressed areas of the structure. This was the first space program to require a comprehensive fracture mechanics approach to prevent structural failures from crack or crack-like defects. As anticipated, some difficult problems were encountered. This paper briefly describes some of them together with the procedure used for fracture control on the orbiter. It is believed that the principles and methods as presented herein can serve as an example of fracture control for aerospace and other industries.
Random Life Curves for Common Engineering Materials
Program incorporates non-Rayleigh effects in evaluating structure life. RMS2 computer program converts constant amplitude fatigue allowables to random-loading allowables, with influence of peak distribution and mean stress considered. RMS2 written in FORTRAN IV.
Predicting crack propagation
Flaw growth under load is predicted in two dimensions with Advanced Crack Propagation Predictive Analysis Program (FLAGR04). FLAGR04 accommodates variety of cracks, crack transitions, stress gradients, changes in material properties, and Willenberg retardation. Program is written in FORTRAN IV for batch execution and is available for CDC and IBM machines.