Godwin†, DC & Shannon, AG 1975, 'A rationale for relating test scores to objectives', International Journal of Mathematical Education in Science and Technology, vol. 6, no. 2, pp. 231-237.
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Questions of educational and statistical validity raised by multiple assessment techniques are examined in terms of educational objectives, errors and distributions of scores. A method of scaling is proposed and its relation to normalizing procedures discussed in recent papers in this journal is indicated. A hypothetical situation provides the framework for the elaboration of the ideas presented. © Taylor & Francis Group, LLC.
Hullett, J, Doan, H & Rosman, G 1975, 'A Modified Receiver for Optical Transmission Systems', IEEE Transactions on Communications, vol. 23, no. 12, pp. 1514-1518.
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A Percival coil connected between the photodetector and amplifier in the receiver of an optical communication system offers the possibility of improved signal-to-noise ratios (SNR's). When the photodetector is ah avalanche diode, the modified receiver requires a lower value of avalanche gain for optimum performance. Copyright © 1975 by The Institute of Electrical and Electronics Engineers, Inc.
LOGANATHAN, P & MAIER, WJ 1975, 'SOME SURFACE CHEMICAL ASPECTS IN TURBIDITY REMOVAL BY SAND FILTRATION', JOURNAL AMERICAN WATER WORKS ASSOCIATION, vol. 67, no. 6, pp. 336-342.
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In order to determine the effects of pH levels, ionic concentrations and polymer dosages on surface chemical properties and the efficiencies of sand filters, a study was conducted using 2 anionic, 2 cationic, and 2 nonionic polymers. Filtration of kaolinite suspensions with sand that had been pretreated with polymers was studied to describe the effects of the presence of Na+, Ca++ and Mg++ ions at different pH levels and at approximately constant ionic strength on particle capture and hence, turbidity removal. Zeta potentials of kaolinite particles and filter sands were determined to help clarify the mechanisms of particle capture in sand filtration. Adsorption of polymers by sand was also measured. The results show that Ca++ and Mg++ ions have a significant effect on removal of kaolinite turbidity by polymer treated filter sand. Calcium and Mg++ ions enhance turbidity removal for all polymer treatments. The enhancement was greatest for anionic polymers and least for cationic ones. There was no significant removal of turbidity in the absence of Ca++ and Mg++ ions when using highly anionic polymer. Zeta potential measurements showed that cationic polymer pretreatment reversed the zeta potential of sand from negative to positive, thus making conditions favorable for the attachment of kaolinite particles (negatively charged) to the surface of the filter sand. The presence of Ca++ and Mg++ ions has no effect on the zeta potential of cationic polymer treated sand and thus not much effect on turbidity removal. The increased effectiveness of turbidity removal obtained with cationic polymer pretreatment indicates that electrostatic forces are dominant.
Waldron, KJ 1975, 'ELIMINATION OF THE BRANCH PROBLEM IN GRAPHICAL BURMESTER MECHANISM SYNTHESIS FOR FOUR FINITELY SEPARATED POSITIONS.', American Society of Mechanical Engineers (Paper), no. 75 -WA/DE-23.
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A graphical construction is presented which, when used for Burmester mechanism synthesis for four finitely separated positions, enables the designer to avoid solutions which will not pass all design positions without being disconnected. The construction is applied to the circle point curve and locates all regions of that curve which give acceptable solutions. The procedure is simple, requiring only construction of circles and straight lines. It is also compatible with Modler's technique for ensuring that the linkage passes the design positions in the desired order.
Waldron, KJ 1975, 'The Order Problem of Burmester Linkage Synthesis', Journal of Engineering for Industry, vol. 97, no. 4, pp. 1405-1406.
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A modification to Modler’s solution to the problem of obtaining a crank to drive the synthesized linkage through the design positions in a specified order is suggested. This permits location of such cranks by inspection of the circle-point curve and the image poles alone.
