781 research outputs found
Fracture Assessment of the WeldβBase Metal Interface of High-Strength Steel Weld Joint
The brittle fracture of the weld joint at low stresses is controlled by high-strength steel characteristics and welding defects. Based on fracture mechanics, the fracture behavior of the weldbase metal interface of a high-strength steel weld joint was studied to reveal the critical locations of the latter. From tensile fracture experiments of 45 steel welded specimens, the loadβdisplacement curve and the fracture modes of weld joints were obtained. The results indicate that the critical loads and fracture modes are influenced by the crack slope angle. The maximum load of interface fracture in weld joints is less than that of the failure in the base metal mainly related to the existence of initial defects in the weld joint. The fracture surface morphology was also detected. It is considered that the fracture surface is influenced by different fracture locations and different microstructure of the weld and base metals. In addition, the critical stress intensity factors of a weld interface crack were calculated based on the critical load and the finite element linear extrapolation method. The linear fracture assessment criteria were proposed, which will be applicable to safety evaluation for the weld joints of high-strength steel structures.Π₯ΡΡΠΏΠΊΠΎΠ΅ ΡΠ°Π·ΡΡΡΠ΅Π½ΠΈΠ΅ ΡΠ²Π°ΡΠ½ΠΎΠ³ΠΎ ΡΠΎΠ΅Π΄ΠΈΠ½Π΅Π½ΠΈΡ ΠΏΡΠΈ Π½ΠΈΠ·ΠΊΠΈΡ
Π½Π°ΠΏΡΡΠΆΠ΅Π½ΠΈΡΡ
Π·Π°Π²ΠΈΡΠΈΡ ΠΎΡ Ρ
Π°ΡΠ°ΠΊΡΠ΅ΡΠΈΡΡΠΈΠΊ Π²ΡΡΠΎΠΊΠΎΠΏΡΠΎΡΠ½ΠΎΠΉ ΡΡΠ°Π»ΠΈ ΠΈ Π΄Π΅ΡΠ΅ΠΊΡΠΎΠ² ΡΠ²Π°ΡΠΊΠΈ. ΠΡΠΈΠ½ΡΠΈΠΏΡ ΠΌΠ΅Ρ
Π°Π½ΠΈΠΊΠΈ ΡΠ°Π·ΡΡΡΠ΅Π½ΠΈΡ ΠΏΠΎΡΠ»ΡΠΆΠΈΠ»ΠΈ ΠΎΡΠ½ΠΎΠ²ΠΎΠΉ ΠΈΠ·ΡΡΠ΅Π½ΠΈΡ ΠΏΠΎΠ²Π΅Π΄Π΅Π½ΠΈΡ ΠΏΠΎΠ²Π΅ΡΡ
Π½ΠΎΡΡΠΈ ΠΊΠΎΠ½ΡΠ°ΠΊΡΠ° ΠΌΠ΅ΡΠ°Π»Π» ΡΠ²Π°ΡΠ½ΠΎΠ³ΠΎ ΡΠ²Π°βΠΎΡΠ½ΠΎΠ²Π½ΠΎΠΉ ΠΌΠ΅ΡΠ°Π»Π» ΠΏΡΠΈ ΡΠ°Π·ΡΡΡΠ΅Π½ΠΈΠΈ ΡΠ²Π°ΡΠ½ΠΎΠ³ΠΎ ΡΠΎΠ΅Π΄ΠΈΠ½Π΅Π½ΠΈΡ Π²ΡΡΠΎΠΊΠΎΠΏΡΠΎΡΠ½ΠΎΠΉ ΡΡΠ°Π»ΠΈ Π΄Π»Ρ Π²ΡΡΠ²Π»Π΅Π½ΠΈΡ ΠΊΡΠΈΡΠΈΡΠ΅ΡΠΊΠΈΡ
ΡΠΎΡΠ΅ΠΊ Π½Π° ΠΏΠΎΡΠ»Π΅Π΄Π½Π΅ΠΌ. ΠΠΎ ΡΠ΅Π·ΡΠ»ΡΡΠ°ΡΠ°ΠΌ ΠΈΡΠΏΡΡΠ°Π½ΠΈΠΉ Π½Π° ΡΠ°Π·ΡΡΡΠ΅Π½ΠΈΠ΅ ΠΏΡΠΈ ΡΠ°ΡΡΡΠΆΠ΅Π½ΠΈΠΈ ΡΠ²Π°ΡΠ½ΡΡ
ΠΎΠ±ΡΠ°Π·ΡΠΎΠ² ΠΈΠ· ΡΡΠ°Π»ΠΈ 45 ΠΏΠΎΡΡΡΠΎΠ΅Π½Π° ΠΊΡΠΈΠ²Π°Ρ ΠΏΡΠΎΠ³ΠΈΠ±βΠ½Π°Π³ΡΡΠ·ΠΊΠ° ΠΈ ΠΏΠΎΠ»ΡΡΠ΅Π½Ρ Π²ΠΈΠ΄Ρ ΠΈΠ·Π»ΠΎΠΌΠΎΠ² Π½Π° ΡΠ²Π°ΡΠ½ΡΡ
ΡΠΎΠ΅Π΄ΠΈΠ½Π΅Π½ΠΈΡΡ
. ΠΠΎΠΊΠ°Π·Π°Π½ΠΎ, ΡΡΠΎ ΡΠ³ΠΎΠ» Π½Π°ΠΊΠ»ΠΎΠ½Π° ΡΡΠ΅ΡΠΈΠ½Ρ ΠΎΠΊΠ°Π·ΡΠ²Π°Π΅Ρ Π²Π»ΠΈΡΠ½ΠΈΠ΅ Π½Π° ΠΊΡΠΈΡΠΈΡΠ΅ΡΠΊΠΈΠ΅ Π½Π°Π³ΡΡΠ·ΠΊΠΈ ΠΈ Π²ΠΈΠ΄Ρ ΠΈΠ·Π»ΠΎΠΌΠΎΠ². ΠΠ°ΠΊΡΠΈΠΌΠ°Π»ΡΠ½Π°Ρ Π½Π°Π³ΡΡΠ·ΠΊΠ°, Π²ΡΠ·ΡΠ²Π°ΡΡΠ°Ρ ΡΠ°Π·ΡΡΡΠ΅Π½ΠΈΠ΅ ΠΏΠΎΠ²Π΅ΡΡ
Π½ΠΎΡΡΠΈ ΠΊΠΎΠ½ΡΠ°ΠΊΡΠ° ΡΠ²Π°ΡΠ½ΠΎΠ³ΠΎ ΡΠΎΠ΅Π΄ΠΈΠ½Π΅Π½ΠΈΡ, Π½ΠΈΠΆΠ΅ Π½Π°Π³ΡΡΠ·ΠΊΠΈ ΡΠ°Π·ΡΡΡΠ΅Π½ΠΈΡ ΠΎΡΠ½ΠΎΠ²Π½ΠΎΠ³ΠΎ ΠΌΠ΅ΡΠ°Π»Π»Π°, ΠΊΠΎΡΠΎΡΠΎΠ΅ Π·Π°Π²ΠΈΡΠΈΡ Π³Π»Π°Π²Π½ΡΠΌ ΠΎΠ±ΡΠ°Π·ΠΎΠΌ ΠΎΡ Π΄Π΅ΡΠ΅ΠΊΡΠΎΠ², ΠΈΠ·Π½Π°ΡΠ°Π»ΡΠ½ΠΎ ΠΏΡΠΈΡΡΡΡΡΠ²ΠΎΠ²Π°Π²ΡΠΈΡ
Π² ΡΠ²Π°ΡΠ½ΠΎΠΌ ΡΠΎΠ΅Π΄ΠΈΠ½Π΅Π½ΠΈΠΈ. Π£ΡΡΠ°Π½ΠΎΠ²Π»Π΅Π½Ρ ΠΌΠΎΡΡΠΎΠ»ΠΎΠ³ΠΈΡ ΠΏΠΎΠ²Π΅ΡΡ
Π½ΠΎΡΡΠΈ ΠΈΠ·Π»ΠΎΠΌΠ° ΠΈ Π²Π»ΠΈΡΠ½ΠΈΠ΅ Π½Π° Π½Π΅Π΅ ΠΌΠ΅ΡΡΠΎΡΠ°ΡΠΏΠΎΠ»ΠΎΠΆΠ΅Π½ΠΈΡ ΠΈΠ·Π»ΠΎΠΌΠΎΠ² ΠΈ ΠΌΠΈΠΊΡΠΎΡΡΡΡΠΊΡΡΡΡ ΠΌΠ΅ΡΠ°Π»Π»Π° ΡΠ²Π°ΡΠ½ΠΎΠ³ΠΎ ΡΠ²Π° ΠΈ ΠΎΡΠ½ΠΎΠ²Π½ΠΎΠ³ΠΎ ΠΌΠ΅ΡΠ°Π»Π»Π°. ΠΡΠΈΡΠΈΡΠ΅ΡΠΊΠΈΠ΅ ΠΊΠΎΡΡΡΠΈΡΠΈΠ΅Π½ΡΡ ΠΈΠ½ΡΠ΅Π½ΡΠΈΠ²Π½ΠΎΡΡΠΈ Π½Π°ΠΏΡΡΠΆΠ΅Π½ΠΈΠΉ Π΄Π»Ρ ΡΡΠ΅ΡΠΈΠ½Ρ Π½Π° ΠΏΠΎΠ²Π΅ΡΡ
Π½ΠΎΡΡΠΈ ΠΊΠΎΠ½ΡΠ°ΠΊΡΠ° ΡΠ°ΡΡΡΠΈΡΡΠ²Π°Π»ΠΈ Π½Π° ΠΎΡΠ½ΠΎΠ²Π°Π½ΠΈΠΈ ΠΊΡΠΈΡΠΈΡΠ΅ΡΠΊΠΎΠΉ Π½Π°Π³ΡΡΠ·ΠΊΠΈ Ρ ΠΏΠΎΠΌΠΎΡΡΡ ΠΊΠΎΠ½Π΅ΡΠ½ΠΎΡΠ»Π΅ΠΌΠ΅Π½ΡΠ½ΠΎΠ³ΠΎ ΠΌΠ΅ΡΠΎΠ΄Π° Π»ΠΈΠ½Π΅ΠΉΠ½ΠΎΠΉ ΡΠΊΡΡΡΠ°ΠΏΠΎΠ»ΡΡΠΈΠΈ. ΠΡΠ΅Π΄Π»ΠΎΠΆΠ΅Π½Ρ ΠΊΡΠΈΡΠ΅ΡΠΈΠΈ ΠΎΡΠ΅Π½ΠΊΠΈ Π»ΠΈΠ½Π΅ΠΉΠ½ΠΎΠ³ΠΎ ΡΠ°Π·ΡΡΡΠ΅Π½ΠΈΡ, ΠΊΠΎΡΠΎΡΡΠ΅ ΠΌΠΎΠ³ΡΡ Π±ΡΡΡ ΠΈΡΠΏΠΎΠ»ΡΠ·ΠΎΠ²Π°Π½Ρ Π΄Π»Ρ ΠΏΡΠΎΠ²Π΅ΡΠΊΠΈ Π½Π°Π΄Π΅ΠΆΠ½ΠΎΡΡΠΈ ΡΠ²Π°ΡΠ½ΡΡ
ΡΠΎΠ΅Π΄ΠΈΠ½Π΅Π½ΠΈΠΉ Π² ΠΊΠΎΠ½ΡΡΡΡΠΊΡΠΈΡΡ
ΠΈΠ· Π²ΡΡΠΎΠΊΠΎΠΏΡΠΎΡΠ½ΠΎΠΉ ΡΡΠ°Π»ΠΈ
Photo-production of Nucleon Resonances and Nucleon Spin Structure Function in the Resonance Region
The photo-production of nucleon resonances is calculated based on a chiral
constituent quark model including both relativistic corrections H{rel} and
two-body exchange currents, and it is shown that these effects play an
important role. We also calculate the first moment of the nucleon spin
structure function g1 (x,Q^2) in the resonance region, and obtain a
sign-changing point around Q^2 ~ 0.27 {GeV}^2 for the proton.Comment: 23 pages, 5 figure
--Dependence of the Gerasimov-Drell-Hearn Sum Rule
We test the Gerasimov-Drell-Hearn (GDH) sum rule numerically by calculating
the total photon absorption cross sections and on
the nucleon via photon excitation of baryon resonances in the constituent quark
model. A total of seventeen, low-lying, non-strange baryon resonances are
included in this calculation. The transverse and longitudinal interference
cross section, , is found to play an important role in the
study of the variation of the sum rule. The results show that the GDH sum
rule is saturated by these resonances at a confidence level of 94%. In
particular, the excitation largely saturates the sum rule at
, and dominates at small . The GDH integral has a strong
-dependence below and changes its sign around . It becomes weakly -dependent for because of
the quick decline of the resonance contributions. We point out that the
variation of the GDH sum rule is very important for understanding the nucleon
spin structure in the non-perturbative QCD region.Comment: revtex, 17 pages, 3 ps figs include
DAMA/LIBRA-phase1 results and perspectives of the phase2
The results obtained with the total exposure of 1.04 ton Γ yr collected by DAMA/LIBRAβphase1 deep underground at the Gran Sasso National Laboratory (LNGS) of the I.N.F.N. during 7 annual cycles are summarized. The DAMA/LIBRAβphase1 and the former DAMA/NaI data (cumulative exposure 1.33 ton Γ yr, corresponding to 14 annual cycles) give evidence at 9.3 Ο C.L. for the presence of Dark Matter (DM) particles in the galactic halo, on the basis of the exploited model independent DM annual modulation signature by using highly radio-pure NaI(Tl) target. No systematic or side reaction able to mimic the exploited DM signature has been found or suggested by anyone over more than a decade. The same data of DAMA/LIBRAβphase1 have also been analyzed searching for possible DM second-order diurnal effect; at present, the DM diurnal modulation amplitude β expected because of the Earth diurnal motion β evaluated on the basis of the DAMA Dark Matter annual modulation results is below the reached experimental sensitivity. Some of the perspectives of the presently running DAMA/LIBRAβphase2 are outlined
Possible implications of the channeling effect in NaI(Tl) crystals
The channeling effect of low energy ions along the crystallographic axes and
planes of NaI(Tl) crystals is discussed in the framework of corollary
investigations on WIMP Dark Matter candidates. In fact, the modeling of this
existing effect implies a more complex evaluation of the luminosity yield for
low energy recoiling Na and I ions. In the present paper related
phenomenological arguments are developed and possible implications are
discussed at some extent.Comment: 16 pages, 10 figures, preprint ROM2F/2007/15, submitted for
publicatio
Measurements of the observed cross sections for exclusive light hadrons containing at , 3.650 and 3.6648 GeV
By analyzing the data sets of 17.3, 6.5 and 1.0 pb taken,
respectively, at , 3.650 and 3.6648 GeV with the BES-II
detector at the BEPC collider, we measure the observed cross sections for
, , ,
and at the three energy
points. Based on these cross sections we set the upper limits on the observed
cross sections and the branching fractions for decay into these
final states at 90% C.L..Comment: 7 pages, 2 figure
Partial wave analysis of J/\psi \to \gamma \phi \phi
Using events collected in the BESII detector, the
radiative decay is
studied. The invariant mass distribution exhibits a near-threshold
enhancement that peaks around 2.24 GeV/.
A partial wave analysis shows that the structure is dominated by a
state () with a mass of
GeV/ and a width of GeV/. The
product branching fraction is: .Comment: 11 pages, 4 figures. corrected proof for journa
Search for the Rare Decays J/Psi --> Ds- e+ nu_e, J/Psi --> D- e+ nu_e, and J/Psi --> D0bar e+ e-
We report on a search for the decays J/Psi --> Ds- e+ nu_e + c.c., J/Psi -->
D- e+ nu_e + c.c., and J/Psi --> D0bar e+ e- + c.c. in a sample of 5.8 * 10^7
J/Psi events collected with the BESII detector at the BEPC. No excess of signal
above background is observed, and 90% confidence level upper limits on the
branching fractions are set: B(J/Psi --> Ds- e+ nu_e + c.c.)<4.8*10^-5, B(J/Psi
--> D- e+ nu_e + c.c.) D0bar e+ e- + c.c.)<1.1*10^-5Comment: 10 pages, 4 figure
Measurements of the observed cross sections for exclusive light hadron production in e^+e^- annihilation at \sqrt{s}= 3.773 and 3.650 GeV
By analyzing the data sets of 17.3 pb taken at GeV
and 6.5 pb taken at GeV with the BESII detector at the
BEPC collider, we have measured the observed cross sections for 12 exclusive
light hadron final states produced in annihilation at the two energy
points. We have also set the upper limits on the observed cross sections and
the branching fractions for decay to these final states at 90%
C.L.Comment: 8 pages, 5 figur
Direct Measurements of Absolute Branching Fractions for D0 and D+ Inclusive Semimuonic Decays
By analyzing about 33 data sample collected at and around 3.773
GeV with the BES-II detector at the BEPC collider, we directly measure the
branching fractions for the neutral and charged inclusive semimuonic decays
to be and , and determine the ratio of the two branching
fractions to be
- β¦