Gravitation Research

Contains reports on two research projects.Joint Services Electronics Programs (U.S. Army, U. S. Navy, and U. S. Air Force) under Contract DAAB07-71-C-0300National Aeronautics and Space Administration (Grant NGR 22-009-526)National Science Foundation (Grant GP-24254

Gravitation Research

Contains research objectives and summary of research.Joint Services Electronics Programs (U. S. Army, U. S. Navy, and U. S. Air Force) under Contract DAAB07-71-C-0300National Aeronautics and Space Administration (Grant NGR 22-009-526)National Science Foundation (Grant GP-24254

Optical and Infrared Spectroscopy

Contains report on one research project.Joint Services Electronics Programs (U. S. Army, U. S. Navy, and U. S. Air Force) under Contract DA 28-043-AMC-02536(E)U. S. Air Force (ESD Contract AF 19(628)-6066)M. I. T. Sloan Fund for Basic Researc

Gravitation Research

Contains research objectives and summary of research.National Aeronautics and Space Administration (Grant NGR 22-009-526)Joint Services Electronics Program (Contract DAAB07-71-C-0300

Infrared Instrumentation and Astronomy

Contains research objectives and summary of research on four research projects.Joint Services Electronics Program (Contract DAAB07-75-C-1346)National Aeronautics and Space Administration (Grant NGR 22-009-526)National Aeronautics and Space Administration (Contract NAS5-22828

Experimental Control of Thermocapillary Convection in a Liquid Bridge

We demonstrate the stabilization of an isolated unstable periodic orbit in a liquid bridge convection experiment. A model independent, nonlinear control algorithm uses temperature measurements near the liquid interface to compute control perturbations which are applied by a thermoelectric element. The algorithm employs a time series reconstruction of a nonlinear control surface in a high dimensional phase space to alter the system dynamics

FAR INFRARED IMPURITY INDUCED ABSORPTION IN ABF3ABF_{3} SINGLE CRYSTALS.

The Research Laboratory of Electronics is supported in part by the Joint Services Electronics Program (Contract DA28-043-AMC-2536(E)). $^{1}$ P.L.Richards, J. Appl, Phys. 34, 1237 (1963).Author Institution: Spectroscopy Laboratory and Research Laboratory of Electronics, Massachusetts Institute of TechnologyThe perovskite fluoride crystals $K(Mg_{x}:Ni_{1-x})F_{3}, KCoF_{3}, KMnF_{3}$ and $RbMnF_{3}$ have been observed in transmission at low temperatures. Several bands of varying strengths were found at liquid helium temperature, and these have been attributed to impurities present in the samples. The stronger bands were also observed at liquid nitrogen temperature. These sharpen and shift to lower frequencies as the temperature is decreased. In $KNiF_{3}$ the band attributed to antiferromagnetic $resonance,^{1}$ at $49 cm^{-1}$, has been found to be incorrectly assigned. This band is also present in $KMgF_{3}$ at $53 cm^{-1}$ and shifts continuously at intermediate concentrations in the mixed crystals. The Spectroscopy Laboratory is supported in part by the National Science Foundation Grant No. GP-4923