1,321 research outputs found
Using laser ultrasound to detect sub-surface defects in metal laser powder bed fusion components
Laser powder bed fusion offers many advantages over conventional manufacturing methods, such as the integration of multiple parts which can result in significant weight-savings. The increased design freedom that layer-wise manufacture allows has also been seen to enhance component performance at little or no added cost. However, for such benefits to be realised, the material quality must first be assured. Laser ultrasonic testing is a non-contact inspection technique which has been proposed as suitable for in-situ monitoring of metal additive manufacturing processes. This paper explores the current capability of this technique to detect manufactured, sub-surface defects in Ti-6Al-4V samples, ex-situ. The results are compared with x-ray computed tomography reconstructions and focus variation microscopy. Whilst laser ultrasound has been used to identify material discontinuities, further work is required before this technique could be implemented in-situ
Genetic and cellular aspects of the establishment of histocompatible stem cells: information gained from an animal model
The establishment of patient-specific histocompatible stem cells may be an alternative for overcoming current limitations in stem cell engineering. We are developing an animal model to assist the establishment of histocompatible, autologous stem cells. In this process, we obtained valuable information on establishing and characterizing stem cells. As an initial step, we succeeded in establishing histocompatible stem cells using preantral follicle cultures and subsequent parthenogenetic activation. The gene expression profile of the established stem cells was similar to that of embryonic stem cells (ESCs) derived from normal fertilization. On the other hand, we propose a way to derive histocompatible, ESC-like cells by co-culturing ovarian stromal cells with feeder fibroblasts, which may allow the derivation of stem cells from somatic tissue. However, more progress regarding the establishment and elucidation on origination of established cell lines is necessary to use this genetic manipulation-free procedure. Nevertheless, relevant information on the process will help to stimulate preclinical research on cell transformation into differentiated, undifferentiated, and even cancerous cells, as well as clinical studies on the application of induced pluripotent cells
A New Constructive Heuristic for the Fm|block|ST
This paper deals with the blocking flow shop problem and proposes new constructive procedures for the total tardiness minimization of jobs. The heuristic has three-phases to build the sequence; the first phase selects the first job to be scheduled, the second phase arranges the remaining jobs and the third phase uses the insertion procedure of NEH to improve the sequence. The proposed procedures evaluate the tardiness associated to the sequence obtained before and after the third phase in order to keep the best of both because the insertion phase can worsen the result. The computational evaluation of these procedures against the benchmark constructive procedures from the literature reveals their good performance.Postprint (published version
Resonances in and
A partial wave analysis is presented of and
from a sample of 58M events in the BES II detector. The
is observed clearly in both sets of data, and parameters of the
Flatt\' e formula are determined accurately: (stat)
(syst) MeV/c, MeV/c, . The data also exhibit a strong peak
centred at MeV/c. It may be fitted with and a
dominant signal made from interfering with a smaller
component. There is evidence that the signal is
resonant, from interference with . There is also a state in with MeV/c and
MeV/c; spin 0 is preferred over spin 2. This state, , is
distinct from . The data contain a strong peak due to
. A shoulder on its upper side may be fitted by interference
between and .Comment: 17 pages, 6 figures, 1 table. Submitted to Phys. Lett.
Measurement of the Branching Fraction of J/psi --> pi+ pi- pi0
Using 58 million J/psi and 14 million psi' decays obtained by the BESII
experiment, the branching fraction of J/psi --> pi+ pi- pi0 is determined. The
result is (2.10+/-0.12)X10^{-2}, which is significantly higher than previous
measurements.Comment: 9 pages, 8 figures, RevTex
Search for K_S K_L in psi'' decays
K_S K_L from psi'' decays is searched for using the psi'' data collected by
BESII at BEPC, the upper limit of the branching fraction is determined to be
B(psi''--> K_S K_L) < 2.1\times 10^{-4} at 90% C. L. The measurement is
compared with the prediction of the S- and D-wave mixing model of the
charmonia, based on the measurements of the branching fractions of J/psi-->K_S
K_L and psi'-->K_S K_L.Comment: 5 pages, 1 figur
First observation of psi(2S)-->K_S K_L
The decay psi(2S)-->K_S K_L is observed for the first time using psi(2S) data
collected with the Beijing Spectrometer (BESII) at the Beijing Electron
Positron Collider (BEPC); the branching ratio is determined to be
B(psi(2S)-->K_S K_L) = (5.24\pm 0.47 \pm 0.48)\times 10^{-5}. Compared with
J/psi-->K_S K_L, the psi(2S) branching ratio is enhanced relative to the
prediction of the perturbative QCD ``12%'' rule. The result, together with the
branching ratios of psi(2S) decays to other pseudoscalar meson pairs
(\pi^+\pi^- and K^+K^-), is used to investigate the relative phase between the
three-gluon and the one-photon annihilation amplitudes of psi(2S) decays.Comment: 5 pages, 4 figures, 2 tables, submitted to Phys. Rev. Let
First Measurements of eta_c Decaying into K^+K^-2(pi^+pi^-) and 3(pi^+pi^-)
The decays of eta_c to K^+K^-2(pi^+pi^-) and 3(pi^+pi^-) are observed for the
first time using a sample of 5.8X10^7 J/\psi events collected by the BESII
detector. The product branching fractions are determined to be B(J/\psi-->gamma
eta_c)*B(eta_c-->K^+K^-pi^+pi^-pi^+pi^-)=(1.21+-0.32+-
0.23)X10^{-4}, and (J/\psi-->gamma eta_c)*
B(eta_c-->pi^+pi^-pi^+pi^-pi^+pi^-)= (2.59+-0.32+-0.48)X10^{-4}. The upper
limit for eta_c-->phi pi^+pi^-pi^+pi^- is also obtained as B(J/\psi-->gamma
eta_c)*B(eta_c--> phi pi^+pi^-pi^+pi^-)< 6.03 X10^{-5} at the 90% confidence
level.Comment: 11 pages, 4 figure
Study of psi(2S) decays to X J/psi
Using J/psi -> mu^+ mu^- decays from a sample of approximately 4 million
psi(2S) events collected with the BESI detector, the branching fractions of
psi(2S) -> eta J/psi, pi^0 pi^0 J/psi, and anything J/psi normalized to that of
psi(2S) -> pi^+ pi^- J/psi are measured. The results are B(psi(2S) -> eta
J/psi)/B(psi(2S) -> pi^+ pi^- J/psi) = 0.098 \pm 0.005 \pm 0.010, B(psi(2S) ->
pi^0 pi^0 J/psi)/B(psi(2S) -> pi^+ pi^- J/psi) = 0.570 \pm 0.009 \pm 0.026, and
B(psi(2S) -> anything J/psi)/B(psi(2S) -> pi^+ pi^- J/psi) = 1.867 \pm 0.026
\pm 0.055.Comment: 13 pages, 8 figure
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