Auslegung: A journal of philosophy, volume 18, number 2 (summer, 1992) book review

Review of Alasdair MacIntyre's "Three Rival Versions of Moral Enquiry: Encyclopedia, Genealogy, and Tradition

The role of unsteadiness in direct initiation of gaseous detonations

An analytical model is presented for the direct initiation of gaseous detonations by a blast wave. For stable or weakly unstable mixtures, numerical simulations of the spherical direct initiation event and local analysis of the one-dimensional unsteady reaction zone structure identify a competition between heat release, wave front curvature and unsteadiness. The primary failure mechanism is found to be unsteadiness in the induction zone arising from the deceleration of the wave front. The quasi-steady assumption is thus shown to be incorrect for direct initiation. The numerical simulations also suggest a non-uniqueness of critical energy in some cases, and the model developed here is an attempt to explain the lower critical energy only. A critical shock decay rate is determined in terms of the other fundamental dynamic parameters of the detonation wave, and hence this model is referred to as the critical decay rate (CDR) model. The local analysis is validated by integration of reaction-zone structure equations with real gas kinetics and prescribed unsteadiness. The CDR model is then applied to the global initiation problem to produce an analytical equation for the critical energy. Unlike previous phenomenological models of the critical energy, this equation is not dependent on other experimentally determined parameters and for evaluation requires only an appropriate reaction mechanism for the given gas mixture. For different fuel–oxidizer mixtures, it is found to give agreement with experimental data to within an order of magnitude

An Explanation of the Supervisory Model used by Elementary Principal Supervisors in the State of Missouri

The goal for this paper was to discuss the efforts a school district has taken to utilize elementary principal supervisors to build and develop principals’ leadership capacities. The question considered was: (1) How are principals supervised and evaluated in one district? Attempting to answer this question is an important step in operationalizing guiding principles that can be shared with principal supervisors. The discussion included the importance of standards, the modeling of instructional supervision by principal supervisors, the reliance of guiding questions and potential data sources. Additional critical factors included coaching with two-way communication based on a trusting, reflective relationship. As the role of principals’ leadership is elevated to increase the performance of teachers and thus the academic performance of students, principal supervisors should be able to provide principals ownership in their supervision and evaluation, evaluate performance based on standards and indicators, deliver feedback, develop trusting relationships, all by making frequent visits to principals’ schools to further the application of principals’ instructional leadership

Cell-Wall Density of Douglas-Fir by Two Optometric Methods

The change in cell-wall density from the water-swollen (1.0 g/cm3) to the oven-dry (1.43 g/cm3) condition is a function of the percent of shrinkage in the cell wall. Cell-wall density obtained opto-metrically by the Dual-Linear measuring micrometer and the dot-grid eyepiece compared favorably with densities reported for mercury porisimeter or picnometric techniques. Both optometric techniques are nondestructive and offer advantages over destructive techniques. Void volumes in the dry cell wall were calculated to be approximately 3.5%, fiber saturation point for extractive-free cell wall about 35%, Average interfibrillar spacing in the water-swollen condition was 20 Å for both earlywood and latewood and in the dry wall: spacing was 4.7 Å for earlywood and 8.3 Å for latewood

Shrinkage and Related Properties of Douglas-Fir Cell Walls

It is often desirable in veneer or particleboard operations, or in pulping, gluing and especially permeability studies, to use nondestructive sampling techniques to estimate specific gravity or wood behavior in situ.Two separate optometric measuring techniques are compared for measuring anatomical parameters of intact, extractive-free wood directly. Excellent estimates of wood specific gravity in the green and oven-dry condition, cell-wall area, lumen area, cell-wall thickness, and density in situ are obtained by both methods. In addition, shrinkage in cell area, cell perimeter, tangential and radial dimensional shrinkage of cells, and volumetric shrinkage are obtained from measurements taken from the water-swollen to the oven-dry condition.Values derived by the two optometric measuring techniques were highly correlated: specific gravity with cell-wall area, basic density with cell-wall thickness