Methods and apparatus, including computer program products, implement techniques for processing data packets in a computer network. A engine and a radiator for cooling the engine are attached to the body frame. , having small dispersion of the resistance, is composed of principal components of about 30 to 97 mol % of BaTiO3, about 1 to 50 mol % of PbTiO3, about 1 to 30 mol % of SrTiO3 and about 1 to 25 mol % of CaTiO3, as well as about 0.