We examined in this work the drying characteristics of wastewater sludge. The drying flux of the constant-rate period for sludge cake could be up to 40% higher than that from a sand bed. Owing to the considerable volume shrinkage of cake, cracks would form and develop on the crack surface, which yielded three-dimensional but rather than the one-dimensional cake structure assumed in conventional drying theories. The crack length was fully developed in the first 30 min of drying, while the width of crack increased linearly with time. Using these data the drying flux from the cracks was estimated. Enhanced drying flux was noticeable which depended on the crack shape and the crossflow velocity.

Co/Ag multilayers with various Co and Ag layer thicknesses were prepared by alternate vapor deposition of pure Co and Ag. The effect of constituent metal layer thickness on the microstructure and magnetic properties of the films was investigated by transmission electron microscopy, Rutherford backscattering, X‐ray diffraction, and vibrating sample magnetometry. The experimental results show that Co layers grow in an fcc structure with the proper relative thickness of constituent metals. The saturation magnetization and coercive force of the multilayers change significantly with layer thickness of Co and Ag. The mechanisms responsible for the phenomena are discussed.

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