The use of review articles in the analysis of a research area

Review articles in the field of polymer science in the seventies are analyzed in order to check their usefulness in describing at a very low cost the development or the state of the art of a field. Results are compared with those obtained through a quantitative study of scientific articles published at the same time in the field. Review articles can be regarded as defining a research programme attempting to link together two networks: polymer properties—as being desirable from market considerations—and polymer structure—as being analyzable by means of academic science, through three kinds of translation strategies. If we thus define a research programme in terms of the mobilization of networks, it is possible to say of review articles that they provide a good representation of the development of networks of problems whose evolution they sketch.We are sad to inform our scientometric colleagues that this is F. Bastide's last contribution as she died in the autum of 1988.     

The power reflected in a SAW RAC

Considerations relating to the design of surface-acoustic-wave (SAW) reflective array pulse compressors (RACS), including the effect of array width on power reflected, the transmitted beam profile and the effect of randomized arrays, are discussed. Only a first-order analysis is used. Potential misunderstandings of these issues that could arise from the existing literature are clarified.     

Null values in nested relational databases

Summary The desire to extend the applicability of the relational model beyond traditional data-processing applications has stimulated interest in nested or non-first normal form relations in which the attributes of a relation can take on values which are sets or even relations themselves. In this paper, we study the role of null values in the nested relational model using an open world assumption. We extend the traditional theory and study the properties of extended operators for nested relations containing nulls. The no-information, unknown, and non-existent interpretation of nulls are discussed and the meaning of empty set is clarified. Finally, contrary to several previous results, we determine that the traditional axiomatization of functional and multivalued dependencies is valid in the presence of nulls.Currently with the Air Force Institute of Technology, AFIT/ENG, Wright-Patterson AFB, OH 45433, USAResearch partially supported by an IBM Faculty Development A ward and NSF grant DCR-8507224     

Portability of three consumer products

Three consumer products (a television set, a personal computer and a typewriter), all considered portable by their respective manufacturers, were evaluated experimentally for portability. Products were not considered portable if the physical and subjective workloads resulting from carrying them over specified distances were excessive. Twenty-two males and six females participated in the experimental investigation and carried the three products for distances of 45·72, 91·44. 137·16 and 182·88 m. Their pulse and ratings of perceived exertion (RPE) of the arms and whole body were recorded and used as measures of physical and perceived workloads. Both physiological and subjective responses to carrying products were significantly influenced by the type of product and carrying distance, regardless of the gender of the person performing the carrying. The results of this study and the design guidelines provided in the literature for one-handed and two-handed carrying tasks led to the conclusion that, of the three products, only the television set could be considered portable.     

Preparation of heavily dopedn-type Ge-Si thermoelectric alloys

Germanium-silicon alloys doped with phosphorus were prepared in vacuum by rapidly pouring the molten alloy into cooled copper moulds containing the phosphorus dopant. Without any further treatment, the ingots are milled into powder of grain size (L 5 µm) and hot pressed. It is shown that a high degree of homogenization of the alloy constituents can be obtained in the final compacts, thus eliminating the need for zone-levelled starting material. It is also shown that this work is in agreement with the plastic flow model of sintering known as the Mackenzie-Shuttleworth-McClelland model. Electrical measurements indicate that the dopant is effectively and uniformly incorporated into the alloy.     

Continuum-type optimality criteria methods for large finite element systems with a displacement constraint. Part I

Continuum-type optimality criteria for the iterative optimization of large finite element systems (i.e. systems with over ten thousand finite elements) are discussed. By investigating optimization problems with up to one million elements and one million variables, it is shown that for a single displacement constraint the proposed method results in a rapid and almost uniform convergence, the rate of which, even for relatively ill-conditioned problems, does not depend significantly on the number of elements. Additional refinements, including upper and lower limits on the cross-sectional dimensions, segmentation, allowance for selfweight and the cost of supports, non-linear and non-separable objective functions, inclusion of shear deformations, built-up cross-sections as well as additional stress constraints and two-dimensional (plane stress) problems, will be considered in Part II of this contribution. The current development constitutes an extension and generalization of pioneering work by Berke, Khot, Venkayya and their associates, whose methods are also reviewed herein. In addition to an elementary truss example and a more advanced beam example, some simple layout optimization problems are considered in this Part. A special feature of the paper is that all numerical results presented are confirmed by closed form analytical solutions.     

The role of trade literature in the communication system

Bibliometric methods in general undervalue technological research. This study examines the relation in literature between technological/industrial journals and scientific journals in the case of the plastics industry and polymer science. Trade-journals cannot be used in a straightforward bibliometric manner, but can be an aid in mapping the different groups and reveal the hidden communication between technological and scientific communities.     

Electrical properties of plasma-sprayed yttria-stabilized zirconia films

Yttria-stabilized zirconia films, 100 to 200 m thick, were prepared by plasma spraying. The electrical properties were investigated by complex impedance spectroscopy. The results are compared with those obtained on sintered pellets prepared with the same powders used for spraying and on commercial single crystals. The ionic conductivity and the activation energies of sprayed films and single crystals are found to be very similar, and no grain-boundary effect is observed in the film complex impedance plots. These results are explained by the high density and purity of the sprayed films.