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This report discusses the design, development and the fabrication of a power hybrid. Foldback current limiting which is self reseting is used whereby withstanding indefinitely a short circuit. Thermal design considerations and thermal analysis are described as well as stability analysis. The maximum current capability of this design is four amperes and forty watts can be dissipated in the power transistors over a wide range of temperatures.

This paper describes a hybrid computer microprogram which plots frequency domain responses for linear systems. The microprogram computes the real and imaginary parts of the system output and displays either Bode or Nyquist plots. Various approaches are discussed and a detailed explanation of the one selected is presented. The major areas of discussion are the sinewave generator, the computation of real and imaginary parts of the system output, the logarithm computation and the digital control logic. The conclusion give s comparison of a Nyquist plot made with the microprogram with one calculated by a digital computer. Possible improvements for the microprogram are also discussed.

<p> Hybrid task-lists are sets of periodic and asynchronous processes. To verifiably schedule hybrid tasks-lists with hard and soft real-time requirements, Xu and Lam proposed Integrated Pre-Run-Time scheduling (IPRTS) [13], a two phase method that first makes use of pre-run-time scheduling techniques, converting some asynchronous tasks with hard deadlines to periodic tasks and reserving processor capacity for the remaining hard deadline asynchronous tasks. These remaining asynchronous tasks are scheduled by a novel run-time scheduler that enforces arbitrary exclusion relations between any combination of periodic and asynchronous processes. The technique has two significant drawbacks: (i) a custom run-time scheduler is required that is not available on existing Real-Time Operating Systems (RTOS) and (ii) in many circumstances the reservation of processor capacity is overly pessimistic, causing the failure of the method for many simple task lists. To overcome these drawbacks, this thesis narrows the set of task-lists considered to those where the asynchronous tasks exclude periodic tasks and periodic processes do not exclude asynchronous tasks. A high priority polling server is then used to handle all hard asynchronous tasks. In cases where the method succeeds, it is easily implementable on any RTOS that has priority based scheduling with phased release times, and inherits the error handling and soft real-time process scheduling capabilities of the RTOS. A set of software tools which partially automates the technique, including an open source implementation of the Xu-Parnas pre-run-time scheduling algorithm [14], has been developed and applied to the examples in the thesis.</p> / Thesis / Master of Applied Science (MASc)

Stomatal response of narrow leaf poplar (P. angustifolia; (PA)), balsam poplar (P. balsamifera; (PB)), cottonwood (P. deltoides; (PD)), and a P. angustifolia X P. balsamifera hybrid (PX) was studied in the field and in controlled environments. Mild water stress was occurring in both field studies, as evidenced by pre-dawn Ψ values of no less than -0.3 MPa; controlled experiments were more severe, with values dropping below -1.0 MPa. Stomatal conductance patterns differed for each species, and suggest that in terms of tolerating drought stress, PX > PA > PB > PD. These patterns were significantly influenced by microclimate conditions; severe conditions caused partial or complete stomatal closure, even in the presence of low water stress. Preconditioning plants through brief, repeated exposure to water stress resulted in stomatal closure at approximately -1.0 MPa, a higher level Ψ than is otherwise indicated for members of the genus Populus. It may thus be a valuable component of drought resistance for these species. Dieback studies indicated dissimilar patterns of dieback between PA and PB; PA experienced dieback on a large number of small branches while that of PB occurred on a small number of main branches. These results suggests that the drought stress response may differ between the two species, and may further indicate that the pattern of dieback is reflective of the physiological response to drought stress. / Thesis / Master of Science (MS)