This textbook is ideal for a course in engineering systems dynamics and controls. The work is a comprehensive treatment of the analysis of lumped parameter physical systems. Starting with a discussion of mathematical models in general, and ordinary differential equations, the book covers input/output and state space models, computer simulation and modeling methods and techniques in mechanical, electrical, thermal and fluid domains. Frequency domain methods, transfer functions and frequency response are covered in detail. The book concludes with a treatment of stability, feedback control (PID, lead-lag, root locus) and an introduction to discrete time systems. This new edition features many new and expanded sections on such topics as: solving stiff systems, operational amplifiers, electrohydraulic servovalves, using Matlab with transfer functions, using Matlab with frequency response, Matlab tutorial and an expanded Simulink tutorial. The work has 40% more end-of-chapter exercises and 30% more examples.

Slip resistance needs were compared between mobility disabled and able-bodied individuals. Subjects walked across a level piezoelectric force plate at slow and fast speeds, and the ratio of the total shear force to the normal force was used as the required coefficient of friction (μr) Near touchdown,μr was found to be significantly greater (p < 0.05 for all significance values) for the mobility disabled (0.64 ± 0.19) than for the able-bodied (0.31 ± 0.07), regardless of the speed of walking. In contrast, slip resistance needs for these two groups were not different near push-off (disabled and able-bodied were each 0.41 ±0.17), although for both groups walking fast required significantly greater slip resistance (0.48 ± 0.19) than walking slow (0.34 ± 0.11). Required coefficient of friction was also calculated as disabled subjects walked up and down a ramp of 1:12 grade. At touchdown, no significant differences among the mean μr values were found for level, uphill, and downhill walking at slow or fast speeds. At push-off, slow-speed walking uphill required significantly greater slip resistance (0.46 ± 0.20) than level (0.34 ± 0.14) or downhill (0.34 ± 0.17) walking. No difference was found among the three grades for the fast speed. It was concluded that the mobility disabled do require greater slip resistance than the able-bodied, and that this puts them at increased risk for falling.

The results of an extensive experimental investigation of the thin water films of thickness less than 0.38 mm (0.015 in.) on the tire-pavement friction are presented. Both laboratory and full-scale field tests involving new measuring equipment were conducted, and a new device was developed for laboratory measurement of rubber-surface friction. Also, a new apparatus was built to measure thickness of thin water films formed on pavement surfaces. The results from the laboratory and field tests indicate that the tire-pavement friction can decrease significantly at very thin water films from 0.025 to 0.230 mm (0.001 to 0.009 in.). A quantitative measure of the effect of water-film thickness on tire-pavement friction is proposed. The effects of tire, vehicle speed, and pavement texture on pavement wetness sensitivity are also investigated.