The structure of nonsingular robot compliance is investigated by applying screw theory to two eigenvalue problems. For the first problem the eigenscrews are demonstrated to be Ball’s (1990) principal screws of the potential. Several new propositions are presented characterizing compliance matrix eigenstructure. Using a novel formulation, the second eigenvalue problem generalizes the three wrench-compliant axes of Dimentberg (1965) to include three twist-compliant axes. These two types of compliant axes are shown to be reciprocal and define conjugate screw systems. The wrench- and twist-compliant axes are demonstrated to the general elements of a compliant axis hierarchy.

The main purposes of filler addition in papermaking are to improve paper properties and reduce cost. The cost reduction is attributed to the low cost of the filler itself and to the energy savings that occur during the papermaking process. In this work, the effects of clay filler addition on the energy savings during the papermaking process, including water drainage, pressing, and drying, were systematically investigated. Experimental results indicated that the addition of filler could dramatically increase the drainage rate and the water removal rates during pressing and drying. With 20% filler addition, the drainage time decreased by 20% compared to the unfilled paper. At a filler content of 23%, the solids content of the handsheets after pressing increased at least 5 absolute points, and the drying rates increased by 20%. All these improvements can offer considerable benefits for paper mills, including enhanced machine speeds and large energy savings.

in Wiley InterScience (www.interscience.wiley.com).Foamed paperboard is a composite material with applications in the consumer products industry. The composite is comprised of paperboard sandwiched between two layers of polymers. One layer foams upon heating while the other acts as a barrier layer. Foaming is caused by the vaporization of the small amount of moisture present in the board and the resulting increase in pressure. The mechanism of foaming was investigated with a combination of high-speed photography, scanning electron microscopy, and infrared thermography using foamed paperboard of different compositions prepared both in the laboratory and on a commercial machine. The surface uniformity of the paper was found to be the overriding paper-related property controlling bubble formation.

The concept of compliant axes is developed from the compliance matrix eigenvalue problem. It is shown that the necessary and sufficient conditions for the existence of a compliant axis are two collinear eigenscrews with eigenvalues of equal magnitude and opposite sign. This leads to a new classification of compliance matrices based on the number of compliant axes. Selected matrices from the literature illustrate both the compliant axis concept and the classification.

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