Self-tuning minimum-variance control of nonlinear systems of the Hammerstein model

Self-tuning is applied to the control of nonlinear systems represented by the Hammerstein model wherein the nonlinearity is any odd-order polynomial. But control costing is not feasible in general. Initial relay control is employed to contain the deviations.     

Critical-field measurements in Nb-Ti composition-modulated alloys

We present measurements of the transition temperature and upper parallel critical field, to 15 kG, of layered Nb-Ti alloys for layer wavelengths between 6 and 6250 Å.Work supported by the NSF under grant DMR 78-24339 and the U.S. Department of Energy. Use was made of facilities funded by the NSF/MRL program under grant DMR 76-80847.On leave from the Institute of Physics, Academia Sinica, Beijing, People's Republic of China.Department of Physics and Astronomy and Materials Research Center.Department of Materials Science and Engineering and Materials Research Center.     

Structural, Optical and Electrical Properties of Evaporated CdSe Films

CdSe films are of great interest for use in thin film photoelectric devices. A simple chemical precipitation method is adopted for the first time to synthesise CdSe powder. Films on glass obtained at different substrate temperatures TS such as 300, 373, 423 and 473 K have been characterised by X-ray diffraction, optical absorption and Hall measurements.     

BCS temperature-dependent superconducting energy gap in domain boundaries of melt-textured YBa2Cu3O7

Attenuation and velocity measurements in low magnetic fields in the superconducting state of a melt-textured sample of YBa₂Cu₃O₇ are reported. Changes in both attenuationα and relative velocitydv/v are observed at the penetration fieldH′ _c1 of its domain boundaries. The change indv/v atH′ _c1 appears to be proportional to the repulsive force between vortices. The change inα atH′ _c1 may be produced by a relaxation process involving superconducting quasiparticles in the vicinity of the normal core of the vortices. Analysis of the relaxation time associated with this process yields a temperature-dependent energy gap which follows the BCS dependence. The relaxation time associated with the process is about 10^?11 sec.