Charge disproportionation and Jahn-Teller distortion in LiNiO2 and NaNiO2: A density functional theory study

Density functional theory calculations have been performed on three potential ground-state configurations of LiNiO2 and NaNiO2. These calculations show that, whereas NaNiO2 shows the expected cooperative Jahn-Teller distortion (and therefore a crystal structure with C2/m symmetry), LiNiO2 shows at least two possible crystal structures very close in energy (within 3 meV/f.u.): P21/c and P2/c. Moreover, one of them (P2/c) shows charge disproportionation of the (expected) Ni3+ cations into Ni2+ and Ni4+. We discuss the implications of this complex ground state for the interpretation of the available electron and neutron structure data, its electronic and complex magnetic behaviour

Influence of skew and cross-coupling on flux-weakening performance of permanent-magnet brushless AC machines

A method is proposed for predicting the flux-weakening performance of permanent-magnet (PM) brushless ac machines accounting for skew and d-q axis cross-coupling. The method is based on a d-q-axis flux-linkage model, a hybrid 2-D finite-element (FE)-analytical method being used to predict the d- and q-axis inductances. However, it only requires 2-D FE analysis of the magnetic field distribution over a cross section of the machine. The developed method is used to predict the torque-speed characteristic of an interior PM brushless ac machine with one stator slot-pitch skew. This is compared with predictions from a direct FE analysis of the machine and validated by measurements

On the Upper Bound of Eigenvalues for Elliptic Equations with Higher Orders

AbstractLet Ω be a bounded domain in Rm with piecewise smooth boundary. We consider the upper bound of the (n+1)th eigenvalue λn+1 for the two problems [formula] and [formula] where l and r are positive integers with l>r, v is the unit outward normal to ∂Ω, and P(t)=al−rtl+al−r−1tl−1+ . . . +a1tr+1 with the constant coefficients al−r=1, ai≥0 for i=1, 2,..., l−r−1. The bounds of λn+1 are expressed in terms of the preceding eigenvalues. This generalizes the inequalities obtained by Payne, Polya, Weinberger, Protter, Hile, and Yeh

Carrier dynamics and infrared-active phonons in c-axis oriented RuSr2_2GdCu2_2O8_8 film

The conductivity spectra of c-axis oriented thin RuSr$_2$GdCu$_2$O$_8$ film on SrTiO$_3$ substrate, prepared by pulsed-laser deposition, are obtained from the analysis of the reflectivity spectra over broad frequency range and temperatures between 10 and 300 K. The free charge carriers are found to be strongly overdamped with their scattering rate (1.0 eV at room temperature) exceeding the plasma frequency (0.55 eV). Four phonon lines are identified in the experimental spectra and assigned to the specific oxygen related in-plane polarized vibrations based on the comparison with the results of a lattice dynamics shell model calculations.Comment: 3 pages, 4 figure

Atomic Processes in Helium-Krypton and Helium-Xenon Mixtures

Coordinated Science Laboratory was formerly known as Control Systems LaboratoryContract DA-36-039-TR US AMC 02208(E

The Effect Of Preventative Drills On Stability Of The Knee In Female Basketball Players

The purpose of this investigation was to study the effect of incorporating three preventative mechanical principles into the practice sessions of an eighth grade girls' basketball team over the duration of one season on the players' knee stability. Three mechanical principles were utilized by 17 females (age=13.7 yrs, mass=52.2 kg, ht=166.8 cm) during each practice: (a) bent knee landings, (b) accelerated rounded turns, and (c) two-three step stops. Knee stability was assessed prior to and at the conclusion of the season by measuring three variables: (a) knee range of motion in extension and flexion tested by a goniometer, (b) comparative strength of the hamstrings and quadriceps muscles tested by an Orthotron at 60 and 180 deg/s, and (c) end of the season joint laxity as an indicator of anterior cruciate ligament displacement tested by a KT-2000 at 28 deg of flexion. A control group of 9 female basketball players (age=12.8 yrs, mass=52.8 kg, ht=160.7 cm) were used for comparison. No significant differences were revealed between groups for knee ROM or joint laxity (L ROM = 145 deg, R ROM = 144 deg; L ACL d = 5.7 mm, R ACL d = 6.5 mm). Significant increases were revealed between pre- and post-season testing for flexion/ extension ratios in both legs at both speeds for experimental subjects (L 60 deg/s = 14%, L 180 deg/s = 15%, R 60 deg/s = 13%, and R 180 deg/s = 8%). A significant decrease was revealed between preand post-season testing for flexion/ extension ratios in the right leg at 180 deg/s for control subjects (7%). Significant increases were revealed between preand post-season testing for p~ak torque of L flexion (6%) at 60 deg/s, L flexion (7%) and extension (13%) at 180 .deg/s, and R flexion (6%) and extension (6%) at 180 deg/s for experimental subjects. A significant increase (

On Decoding Projective Geometry Codes

Coordinated Science Laboratory was formerly known as Control Systems LaboratoryJoint Services Electronics Program / DAAB 07-67-C-0199Rome Air Development Center / F30602-70-C-0014 (EMKC

On Decoding Euclidean Geometry Codes

Coordinated Science Laboratory was formerly known as Control Systems LaboratoryJoint Services Electronics Program / DAAB 07-67-C-0199Rome Air Development Center / F30602-70-C-0014 (EMKC