A comprehensive program of study and measurement of the Haystack reflector has been conducted, resulting in a performance improvement of approximately 40 percent. A stochastic approach to data taking and analysis combined with the benefits of an on-site computer provided analytical control of the adjustment operation, and at the same time assured a short reaction time between receipt of the raw...

We present a catalog of type-specific, direct quadric fitting methods: Given a selection of a point cloud or triangle mesh, and a desired quadric type (e.g. cone, ellipsoid, paraboloid, etc), our methods recover a best-fit surface of the given type to the given data. Type-specific quadric fitting methods are scattered throughout the literature; here we present a thorough, practical collection i...

Today, Newton’s Method is commonly used in machine learning and optimization to locate local minima of cost functions. Because it is such a general tool, the cost functions that is implemented on can range widely in terms of both their dimensionality and their complexity. However, little is understood about how Newton’s Method performs on cost functions with different dimensionalities and compl...

We report continuous wave (cw) operation of a terahertz quantum-cascade vertical-external-cavity surface-emitting laser with an external cavity length approximately 30 mm, benefited by intra-cryostat focusing cavity. Compared to previous plano–plano cavities, off-axis paraboloid mirror is introduced into the as element reduce diffraction loss and enable cw lasing using small-area metasurfaces l...

The dynamic behaviour of spiral waves rotating on surfaces of curved reaction–diffusion systems depends strongly on the curvature of the surface. It was shown in an earlier experiment that a spiral in a Belousov–Zhabotinsky system on a paraboloid drifts to the point of highest Gaussian curvature, as predicted numerically and analytically. Beyond this, theoretical work predicts an increase of th...