Abstract: A pipe comprises an outer surface and an inner surface, where the inner surface includes an abrasion resistant material layer covering a substantial portion thereof. An adhesive layer affixes the abrasion resistant material layer to the inner surface. The abrasion resistant layer can reduce and prevent erosion-corrosion of the inner surface of a pipe transporting slurry.

Abstract: An antenna array includes four closely spaced, linearly arranged antenna columns. At least two of the columns, e.g., the center two columns, are dual-polarized. Spacing between neighboring columns is about ½?, where ? is the free space wavelength at the network carrier frequency. Each column includes a first vertical linear array of radiating elements or groups of elements (sub-arrays) connected to a port. The dual-polarized columns each further include a second linear array of radiating elements oriented at a different polarization than the first array. (For example, horizontal/vertical or slant 45°.) Array ports are connected with four RF feed cables using duplexers in such a way so as to provide two different antenna configurations for forward link and reverse link frequencies, namely, a four-column closely spaced beam-forming array at the forward link and a two-column dual-polarized array at the reverse link for 4-branch diversity reception.