Diffraction patterns of synthetic Co-åkermanite, Ca2CoSi2O7, reveal distinct satellite reflections at room temperature. An incommensurate modulation in this material has been determined by five-dimensional refinement of the structure. The basic structure is tetragonal P421m, unit-cell dimensions a=7.8417(6), c=5.0249(3)Å, V=308.99Å3, Z=2, M=307.26, Dx=3.302g•cm-3, MoKα with graphite monochromator, μ=47.7cm-1, F(000)=302, R=0.049 for 734 unique reflections. The modulated structure is also tetragonal Pp421mp4mg, k1=0.2913×(a*+b*), k2=0.2913×(-a*+b*), where k1, k2 wave vectors and a*, b* reciprocal lattice vectors of the basic structure, R=0.098 for 3915 unique reflections. The modulation is caused by the shifts of the constituent atoms.
Almost all electric energy of electric industries is generated by synchronous generators, which are either salient-pole synchronous generators or have saliency to some extent. As the rotor rotates, inductances of the three phase winding vary due to the saliency and it makes analysis of generator performance difficult. Even adequate computer simulations have not been provided by the conventional theories, such as the d, q axis theory. In this paper the spiral vector method will be applied to analyses of the salient-pole synchronous generator, and adequate analytical solutions and computer simultations will be derived.