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A procedure for evaluating the effectiveness of oil-dispersing chemicals has been developed. Using the apparatus originally designed for the Navy specification for solvent-emulsifiers, test conditions were adapted to correspond more closely to typical environmental conditions. Test conditions having the greatest effect on dispersant performance included: type of oil, composition of salt water solution, degree of agitation of chemical/oil mixture, and the degree of contact between chemical and oil prior to agitation. Results from this modified procedure, the Simulated Environmental Tank (SET) Test, correspond well with results from simple field tests. Field tests have limited precision and reproducibility. This lack of a reliable index of field performance with which to compare laboratory results hinders refinement of standard test procedures. The SET Test, which produces results corresponding favorably with field performance, to the extent field performance can be determined, and which simulates typical environmental conditions, is proposed as a meaningful interim solution to this problem of dispersant evaluation.

The submaximal, constrained nature of joystick manipulation makes it difficult to select an appropriate technique for upper limb electromyography (EMG) normalization. The purpose of this study was to determine an appropriate submaximal isometric normalization method to quantify EMG from shoulder muscle activation in hydraulic-actuation joystick operators that could later be implemented in field settings. Surface EMG data were collected from the upper trapezius, posterior deltoid, and anterior deltoid of seventeen subjects while operating a hydraulic-actuation joystick. EMG data were normalized using two techniques: muscle specific (mRVC) and task specific (three joystick positions: start-tRVCStart, middle-tRVCMiddle and end-tRVCEnd). No significant differences (p ⩽ 0.05) were observed for intersubject coefficient of variation (CV) between normalization procedures (mRVC, tRVCStart, tRVCMiddle tRVCEnd, un-normalized). These equivocal findings do not favour the use of any one of the submaximal normalization procedures over another. However, though not statistically significant, the un-normalized (0.68 ± 0.15) CVs were lower than those of normalized ensembles (0.96 ± 0.24) suggesting that for constrained, submaximal tasks, it may not be necessary to normalize EMG. Although this analysis was applied to upper limb EMG during joystick manipulation, the results have potential application to other submaximal upper limb tasks which are constrained and repetitive in nature thus including many assembly line jobs.

The purpose of this work was to quantify upper limb and joystick kinematics, muscle activation of the prime movers and stabilizers of the shoulder (anterior deltoid, posterior deltoid and upper trapezius) as well as torque exerted by operators of hydraulic-actuation joystick controllers. Dynamic and impact torques were captured through the use of an instrumented joystick. Results indicate that the impact torque (5.36 ± 1.75 N·m for forward motion) sustained as the joystick reaches the end range of motion is substantial and is more than twice that of the operator exerted torque prior to reaching the hard endpoint. EMG data confirm that the upper trapezius is in a state of constant but low level activation, which may be largely attributable to postural demands forced upon the operator by the armrest.