Abstract: There is described a system for preventing accumulation of meltable precipitation on a surface. The system generally has: a concrete slab having a slab body with a top surface opposed to a bottom surface, the slab body having electrically conductive concrete; a plurality of elongated electrodes within said slab body, a first set of said elongated electrodes being spaced apart from one another proximate to said top surface and a second set of said elongated electrodes being spaced apart from one another away from said elongated electrodes of said first set, the elongated electrodes of the first set being interspersed with the elongated electrodes of the second set; and a voltage source being electrically connected to the elongated electrodes and being operable to apply a voltage to said elongated electrodes, thereby generating heat within said slab body for melting said accumulation on said top surface.

Abstract: A colorless tunable dispersion compensator for compensating for chromatic dispersion in a multi-channel light signal is provided. The compensator includes a multi-channel Bragg grating extending along a waveguide. Dispersion tuning means, such as a temperature gradient inducing device, are provided for tuning the dispersion characteristics of the wavelength channels. Wavelength shifting means are also provided for uniformly shifting the central wavelengths of all channels independently of their dispersion characteristics. A uniform temperature inducing or strain applying assembly can be used for this purpose.

Abstract: Improved methods and apparatus is disclosed for electrical testing of electronic circuits such as those existing in microcircuit devices including chip carriers, printed circuit boards and substrates. The invention provides for the testing of the continuity of electronic circuits in progressively smaller devices having increased density of circuits and having pads closely spaced. A quasi-fluidized bed of conductive particles is provided for effectively contacting pads on a first side of a substrate. Pads on another side of the substrate which are connected to the pads on the first side are then contacted by a test device. The circuit interconnecting respective pads on the two sides of the substrate can then be assessed for electrical continuity.

Abstract: Improved methods and apparatus is disclosed for electrical testing of electronic circuits such as those existing in microcircuit devices including chip carriers, printed circuit boards and substrates. The invention provides for the testing of the continuity of electronic circuits in progressively smaller devices having increased density of circuits and having pads closely spaced. A quasi-fluidized bed of conductive particles is provided for effectively contacting pads on a first side of a substrate. Pads on another side of the substrate which are connected to the pads on the first side are then contacted by a test device. The circuit interconnecting respective pads on the two sides of the substrate can then be assessed for electrical continuity.