Ordering behaviors of Cd−Mg and Cd−Zn alloys with the h.c.p.-type structure

The structure dependent energy and the ordering energy for an h.c.p.-type binary alloy composed of simple metals are derived from a basis of the method of pseudopotentials. The expressions of the energies are characterized by the long-range and short-range order parameters.The long-range ordering energy is calculated for alloys in the Cd?Mg system. The numerical results reproduce well the fact that the Cd?Mg system has the B19-type ordered phase around the stoichiometric composition of MgCd and the D0₁₉-type ones around Mg₃Cd and MgCd₃. The calculated local ordering energies explain successfully the existence of a short-range order in the Cd?Mg system and also the insolubility between Cd and Zn.     

ClassicalA n -W-geometry

By analyzing theextrinsic geometry of two dimensional surfaces chirally embedded inC P ⁿ (theC P ⁿ W-surface [1]), we give exact treatments in various aspects of the classical W-geometry in the conformal gauge: First, the basis of tangent and normal vectors are defined at regular points of the surface, such that their infinitesimal displacements are given by connections which coincide with the vector potentials of the (conformal)A _n -Toda Lax pair. Since the latter is known to be intrinsically related with the W symmetries, this gives the geometrical meaning of theA _n W-Algebra. Second, W-surfaces are put in one-to-one correspondence with solutions of the conformally-reduced WZNW model, which is such that the Toda fields give the Cartan part in the Gauss decomposition of its solutions. Third, the additional variables of the Toda hierarchy are used as coordinates ofC P ⁿ . This allows us to show that W-transformations may be extended as particular diffeomorphisms of this target-space. Higher-dimensional generalizations of the WZNW equations are derived and related with the Zakharov-Shabat equations of the Toda hierarchy. Fourth, singular points are studied from a global viewpoint, using our earlier observation [1] that W-surfaces may be regarded as instantons. The global indices of the W-geometry, which are written in terms of the Toda fields, are shown to be the instanton numbers for associated mappings of W-surfaces into the Grassmannians. The relation with the singularities of W-surface is derived by combining the Toda equations with the Gauss-Bonnet theorem.     

Novel photoproducts of allethrin

Two polar photoproducts of allethrin, allethrolone and allethronyl glyoxylate, were isolated and identified. The formation mechanisms of these were also discussed.     

Field oriented control of induction machines employing rotor endring current detection

The usual method of induction motor torque control uses the indirect field orientation principle in which the rotor speed is sensed and slip frequency is added to form the stator impressed frequency. Unfortunately, the rotor resistance varies as the motor heats up under load thereby changing the rotor time constant which has a deleterious effect on the torque response. In this paper two new field oriented control schemes are presented which employ rotor end ring current detection and thereby remove the dependence of the controller accuracy on temperature so that the controller is entirely independent of rotor time constant variations. The field orientation schemes do not require an incremental encoder for rotor position sensing. The motor torque can be accurately controlled even down to zero speed operation     

Spin structure of the nucleon

Based on an infinite sublayer quark model, we determine the fraction of nucleon spin carried by subquarks.     

Proposed wide-band and low-drive-power electrooptic modulators

Novel methods for the wide-band and low-drive-power electrooptic modulators are proposed. This wide-band and low-drive-power performance is obtained by the utilization of relative electrical and optical delays. Both a lumped and a traveling-wave configuration are described.