413 research outputs found
Performance of Halbach magnetized brushless AC motors
The steady-state performance of Halbach magnetized brushless ac machines when operated in constant torque and flux-weakening modes is investigated both theoretically and experimentally, with particular emphasis on the influence of cross-coupling magnetic saturation on the torque capability
Finite temperature strong-coupling expansions for the Kondo lattice model
Strong-coupling expansions, to order , are derived for the Kondo
lattice model of strongly correlated electrons, in 1-, 2- and 3- dimensions at
arbitrary temperature. Results are presented for the specific heat, and spin
and charge susceptibilities.Comment: revtex
Dynamic and Postdeformation Recrystallization of Nuclear-Grade 316LN Stainless Steel
Nuclear-grade 316LN stainless steel was subjected to single and double compressions at 1173β1473 K and strain rates of 0.01β10 sβ»ΒΉ. The dynamic and postdeformation recrystallization was investigated through analysis of the stressβstrain curves and microstructure evolution. The thermal deformation equation and the quantitative relationships between the critical stress for the initiation of dynamic recrystallization and the ZenerβHollomon parameter, Z, and between the dynamic recrystallization grain size D and Z were derived. Dynamic recrystallization developed through an ordinary mechanism at low Z values and through a necklace mechanism at high Z values, with a critical Z value of about 3.6 10ΒΉβΆ . At 1273β1473 K, softening of 316LN stainless steel after deformation was characterized by an Avrami-type equation, where the Avrami parameter, n, has no appreciable temperature dependence, and an average value of n and the activation energy, Qrex , were 0.68 and 129 kJ/mol, respectively.ΠΠ΅ΡΠΆΠ°Π²Π΅ΡΡΠ°Ρ ΡΡΠ°Π»Ρ 316LN ΡΠ΄Π΅ΡΠ½ΠΎΠ³ΠΎ ΠΊΠ»Π°ΡΡΠ° ΠΏΠΎΠ΄Π²Π΅ΡΠ³Π°Π»Π°ΡΡ ΠΎΠ΄Π½ΠΎ- ΠΈ Π΄Π²ΡΠΊΡΠ°ΡΠ½ΠΎΠΌΡ ΡΠΆΠ°ΡΠΈΡ ΠΏΡΠΈ 1173...1473 Π ΠΈ ΡΠΊΠΎΡΠΎΡΡΠΈ Π΄Π΅ΡΠΎΡΠΌΠ°ΡΠΈΠΈ 0,01...10 Ρβ»ΒΉ. ΠΠΈΠ½Π°ΠΌΠΈΡΠ΅ΡΠΊΠ°Ρ ΠΈ ΠΏΠΎΡΡΠ΄Π΅ΡΠΎΡΠΌΠ°ΡΠΈΠΎΠ½Π½Π°Ρ ΡΠ΅ΠΊΡΠΈΡΡΠ°Π»Π»ΠΈΠ·Π°ΡΠΈΡ ΠΈΠ·ΡΡΠ°Π»Π°ΡΡ Ρ ΠΏΠΎΠΌΠΎΡΡΡ Π°Π½Π°Π»ΠΈΠ·Π° Π·Π°Π²ΠΈΡΠΈΠΌΠΎΡΡΠΈ Π΄Π΅ΡΠΎΡΠΌΠ°ΡΠΈΠΈ ΠΎΡ Π½Π°ΠΏΡΡΠΆΠ΅Π½ΠΈΡ ΠΈ ΡΠ°Π·Π²ΠΈΡΠΈΡ ΠΌΠΈΠΊΡΠΎΡΡΡΡΠΊΡΡΡΡ. ΠΡΠ»ΠΈ Π²ΡΠ²Π΅Π΄Π΅Π½Ρ ΡΡΠ°Π²Π½Π΅Π½ΠΈΠ΅ ΡΠ΅ΠΏΠ»ΠΎΠ²ΠΎΠΉ Π΄Π΅ΡΠΎΡΠΌΠ°ΡΠΈΠΈ ΠΈ ΠΊΠΎΠ»ΠΈΡΠ΅ΡΡΠ²Π΅Π½Π½ΡΠ΅ Π·Π°Π²ΠΈΡΠΈΠΌΠΎΡΡΠΈ ΠΌΠ΅ΠΆΠ΄Ρ ΠΊΡΠΈΡΠΈΡΠ΅ΡΠΊΠΈΠΌ Π½Π°ΠΏΡΡΠΆΠ΅Π½ΠΈΠ΅ΠΌ ΠΈΠ½ΠΈΡΠΈΠΈΡΠΎΠ²Π°Π½ΠΈΡ Π΄ΠΈΠ½Π°ΠΌΠΈΡΠ΅ΡΠΊΠΎΠΉ ΡΠ΅ΠΊΡΠΈΡΡΠ°Π»Π»ΠΈΠ·Π°ΡΠΈΠΈ ΠΈ ΠΏΠ°ΡΠ°ΠΌΠ΅ΡΡΠΎΠΌ ΠΠ΅Π½Π΅ΡΠ° Π₯ΠΎΠ»Π»ΠΎΠΌΠΎΠ½Π° Z, Π° ΡΠ°ΠΊΠΆΠ΅ ΠΌΠ΅ΠΆΠ΄Ρ ΡΠ°Π·ΠΌΠ΅ΡΠΎΠΌ Π·Π΅ΡΠ½Π° D ΠΏΡΠΈ Π΄ΠΈΠ½Π°ΠΌΠΈΡΠ΅ΡΠΊΠΎΠΉ ΡΠ΅ΠΊΡΠΈΡΡΠ°Π»Π»ΠΈΠ·Π°ΡΠΈΠΈ ΠΈ Z. ΠΠΈΠ½Π°ΠΌΠΈΡΠ΅ΡΠΊΠ°Ρ ΡΠ΅ΠΊΡΠΈΡΡΠ°Π»Π»ΠΈΠ·Π°ΡΠΈΡ ΡΠ°Π·Π²ΠΈΠ²Π°Π»Π°ΡΡ ΠΏΠΎ ΠΎΠ±ΡΡΠ½ΠΎΠΌΡ ΠΌΠ΅Ρ
Π°Π½ΠΈΠ·ΠΌΡ ΠΏΡΠΈ Π½ΠΈΠ·ΠΊΠΈΡ
Π·Π½Π°ΡΠ΅Π½ΠΈΡΡ
Z ΠΈ ΠΏΠΎ ΠΌΠ΅Ρ
Π°Π½ΠΈΠ·ΠΌΡ ΠΎΠΆΠ΅ΡΠ΅Π»ΡΡ ΠΏΡΠΈ Π²ΡΡΠΎΠΊΠΈΡ
Π·Π½Π°ΡΠ΅Π½ΠΈΡΡ
Z, ΠΏΡΠΈ ΠΊΡΠΈΡΠΈΡΠ΅ΡΠΊΠΎΠΌ Π·Π½Π°ΡΠ΅Π½ΠΈΠΈ Z ΠΏΡΠΈΠΌΠ΅ΡΠ½ΠΎ 3 6 10ΒΉβΆ. ΠΡΠΈ 1273...1473 Π ΡΠ°Π·ΡΠΏΡΠΎΡΠ½Π΅Π½ΠΈΠ΅ Π½Π΅ΡΠΆΠ°Π²Π΅ΡΡΠ΅ΠΉ ΡΡΠ°Π»ΠΈ 316LN ΠΏΠΎΡΠ»Π΅ Π΄Π΅ΡΠΎΡΠΌΠΈΡΠΎΠ²Π°Π½ΠΈΡ ΠΎΠΏΠΈΡΡΠ²Π°Π΅ΡΡΡ ΡΡΠ°Π²Π½Π΅Π½ΠΈΠ΅ΠΌ ΠΠ²ΡΠ°ΠΌΠΈ, Π³Π΄Π΅ ΠΏΠ°ΡΠ°ΠΌΠ΅ΡΡ ΠΠ²ΡΠ°ΠΌΠΈ n Π½Π΅ ΠΏΡΠΎΡΠ²Π»ΡΠ΅Ρ Π²ΡΡΠ°ΠΆΠ΅Π½Π½ΠΎΠΉ ΡΠ΅ΠΌΠΏΠ΅ΡΠ°ΡΡΡΠ½ΠΎΠΉ Π·Π°Π²ΠΈΡΠΈΠΌΠΎΡΡΠΈ, Π° Π΅Π³ΠΎ ΡΡΠ΅Π΄Π½Π΅Π΅ Π·Π½Π°ΡΠ΅Π½ΠΈΠ΅ ΠΈ ΡΠ½Π΅ΡΠ³ΠΈΡ Π°ΠΊΡΠΈΠ²Π°ΡΠΈΠΈ Qrex ΡΠΎΡΡΠ°Π²Π»ΡΡΡ 0,68 ΠΈ 129 ΠΊΠΠΆ/ΠΌΠΎΠ»Ρ ΡΠΎΠΎΡΠ²Π΅ΡΡΡΠ²Π΅Π½Π½ΠΎ
Kondo spin liquid and magnetically long-range ordered states in the Kondo necklace model
A simplified version of the symmetric Kondo lattice model, the Kondo necklace
model, is studied by using a representation of impurity and conduction electron
spins in terms of local Kondo singlet and triplet operators. Within a mean
field theory, a spin gap always appears in the spin triplet excitation spectrum
in 1D, leading to a Kondo spin liquid state for any finite values of coupling
strength (with as hopping and as exchange); in 2D and 3D cubic
lattices the spin gaps are found to vanish continuously around and , respectively, where quantum phase transitions
occur and the Kondo spin liquid state changes into an antiferromagnetically
long-range ordered state. These results are in agreement with variational Monte
Carlo, higher-order series expansion, and recent quantum Monte Carlo
calculations for the symmetric Kondo lattice modelComment: Revtex, four pages, three figures; to be published in Physical Review
B1, 1 July (2000
Finite temperature properties of the 2D Kondo lattice model
Using recently developed Lanczos technique we study finite-temperature
properties of the 2D Kondo lattice model at various fillings of the conduction
band. At half filling the quasiparticle gap governs physical properties of the
chemical potential and the charge susceptibility at small temperatures. In the
intermediate coupling regime quasiparticle gap scales approximately linearly
with Kondo coupling. Temperature dependence of the spin susceptibility reveals
the existence of two different temperature scales. A spin gap in the
intermediate regime leads to exponential drop of the spin susceptibility at low
temperatures. Unusual scaling of spin susceptibility is found for temperatures
above 0.6 J. Charge susceptibility at finite doping reveals existence of heavy
quasiparticles. A new low energy scale is found at finite doping.Comment: REVTeX, 7 pages, 7 figure
The spin and charge gaps of the half-filled N-leg Kondo ladders
In this work, we study N-leg Kondo ladders at half-filling through the
density matrix renormalization group. We found non-zero spin and charge gaps
for any finite number of legs and Kondo coupling . We also show evidence
of the existence of a quantum critical point in the two dimensional Kondo
lattice model, in agreement with previous works. Based on the binding energy of
two holes, we did not find evidence of superconductivity in the 2D Kondo
lattice model close to half-filling.Comment: 4 pages, 1 table, 3 fig
Thermodynamics of the half-filled Kondo lattice model around the atomic limit
We present a perturbation theory for studying thermodynamic properties of the
Kondo spin liquid phase of the half-filled Kondo lattice model. The grand
partition function is derived to calculate chemical potential, spin and charge
susceptibilities and specific heat. The treatment is applicable to the model
with strong couplings in any dimensions (one, two and three dimensions). The
chemical potential equals zero at any temperatures, satisfying the requirement
of the particle-hole symmetry. Thermally activated behaviors of the
spin(charge) susceptibility due to the spin(quasiparticle) gap can be seen and
the two-peak structure of the specific heat is obtained. The same treatment to
the periodic Anderson model around atomic limit is also briefly discussed.Comment: 5 pages, 3 figures, to appear in Phys. Rev.
BESII Detector Simulation
A Monte Carlo program based on Geant3 has been developed for BESII detector
simulation. The organization of the program is outlined, and the digitization
procedure for simulating the response of various sub-detectors is described.
Comparisons with data show that the performance of the program is generally
satisfactory.Comment: 17 pages, 14 figures, uses elsart.cls, to be submitted to NIM
Study of J/psi decays to Lambda Lambdabar and Sigma0 Sigma0bar
The branching ratios and Angular distributions for J/psi decays to Lambda
Lambdabar and Sigma0 Sigma0bar are measured using BESII 58 million J/psi.Comment: 11 pages, 5 figure
- β¦