The Leadership Challenge: Preparing and Developing Catholic School Principals

The increasing emphasis on the myriad of leadership preparation standards have caused university principal preparation programs to necessarily focus on the more secular aspect of leading schools. For the Catholic school principal, this has left little focus on the development of critical strategies to lead for Catholic Identity and faith formation. This article suggests using the National Standards and Benchmarks for Effective Catholic Schools as a framework for Catholic principal preparation programs to address this issues. Additional suggests for program development are also offered

An Assessment of NASA Aeropropulsion Technologies: A System Study

Aviation industry s robust growth rate has given rise to growing concerns about the contribution that aviation emissions will make to local air quality and global climate change. Over the last several years, NASA has been engaged in the development of aeropropulsion technologies with specific objectives to reduce aircraft emissions. A system analysis was performed to evaluate the potential impact of these propulsion technologies on aircraft CO2 (directly proportional to fuel burn) and NOx reductions. A large subsonic aircraft, with two 396-kN thrust (85,000-pound) engines was chosen for the study. Performance benefit estimates are presented for each technology, with a summary of potential emissions reduction possible from the development of these technologies. The results show that NASA s aeropropulsion technologies have the potential to significantly reduce the CO2 and NO(x) emissions. The results are used to support informed decision-making on the development of aeropropulsion technology portfolio for CO2 and NO(x) reductions

Dust trapping in inviscid vortex pairs

The motion of tiny heavy particles transported in a co-rotating vortex pair, with or without particle inertia and sedimentation, is investigated. The dynamics of non-inertial sedimenting particles is shown to be chaotic, under the combined effect of gravity and of the circular displacement of the vortices. This phenomenon is very sensitive to particle inertia, if any. By using nearly hamiltonian dynamical system theory for the particle motion equation written in the rotating reference frame, one can show that small inertia terms of the particle motion equation strongly modify the Melnikov function of the homoclinic trajectories and heteroclinic cycles of the unperturbed system, as soon as the particle response time is of the order of the settling time (Froude number of order unity). The critical Froude number above which chaotic motion vanishes and a regular centrifugation takes place is obtained from this Melnikov analysis and compared to numerical simulations. Particles with a finite inertia, and in the absence of gravity, are not necessarily centrifugated away from the vortex system. Indeed, these particles can have various equilibrium positions in the rotating reference frame, like the Lagrange points of celestial mechanics, according to whether their Stokes number is smaller or larger than some critical value. An analytical stability analysis reveals that two of these points are stable attracting points, so that permanent trapping can occur for inertial particles injected in an isolated co-rotating vortex pair. Particle trapping is observed to persist when viscosity, and therefore vortex coalescence, is taken into account. Numerical experiments at large but finite Reynolds number show that particles can indeed be trapped temporarily during vortex roll-up, and are eventually centrifugated away once vortex coalescence occurs.Comment: 7 figure

Adaptive Engine Technologies for Aviation CO2 Emissions Reduction

Adaptive turbine engine technologies are assessed for their potential to reduce carbon dioxide emissions from commercial air transports.Technologies including inlet, fan, and compressor flow control, compressor stall control, blade clearance control, combustion control, active bearings and enabling technologies such as active materials and wireless sensors are discussed. The method of systems assessment is described, including strengths and weaknesses of the approach. Performance benefit estimates are presented for each technology, with a summary of potential emissions reduction possible from the development of new, adaptively controlled engine components

Entwicklungsperspektiven der ökologischen Landwirtschaft in Deutschland

Hohe Umweltbelastungen und eine wachsende Weltbevölkerung stellen die Landwirtschaft vor große Herausforderungen. Die ökologische Landwirtschaft gilt dabei als besonders umweltfreundlich. Die Studie zeigt: Ökolandbau ist gut, aber nicht optimal. Einige seiner Prinzipien erschweren es die Ökoeffizienz (Umweltwirkung pro Produkteinheit) zu verbessern. Ein Ökolandbau 4.0, der offener gegenüber Neuerungen wäre, würde hier Abhilfe schaffen. Um die Ökoeffizienz der konventionellen Landwirtschaft zu steigern, wird die Etablierung eines neuen Standards - der ökologisch optimierten, integrierten Produktion (IP+) - vorgeschlagen. Die Studie zeigt somit Entwicklungsperspektiven für den Ökolandbau und die konventionelle Landwirtschaft gleichermaßen auf