9,056 research outputs found
Large-scale Advanced Prop-fan (LAP) static rotor test report
Discussed is Static Rotor Testing of the SR-7L Large Scale Advanced Prop-Fan (LAP). The LAP is an advanced 9 foot diameter, 8 bladed propeller designed and built by Hamilton Standard under contract to the NASA Lewis Research Center. The Prop-Fan employs thin swept blades to provide efficient propulsion at flight speeds up to Mach .85. Static Testing was conducted on a 10,000 HP whirl rig at Wright Patterson Air Force Base. The test objectives were to investigate the Prop-Fan static aerodynamic and structural dynamic performance, determine the blade steady state stressers and deflections and to measure steady and unsteady pressures on the SR-7L blade surface. The measured performance of the LAP correlated well with analytical predictions at blade pitch angles below 30 deg. A stall buffet phenomenon was observed at blade pitch angles above 30 deg. This phenomenon manifested itself by elevated blade vibratory stress levels and lower than expected thrust produced and power absorbed by the Prop-Fan for a given speed and blade angle
On the Analysis of Small Displacements of Truss Joints
By emphasizing the kinematic aspects and implications of strain in truss analysis, it is shown that joint displacements can be computed in a straightforward manner
Exploring Physical Intuition in Elementary Pressure Vessels
It is shown that displacement calculations for two classical ‘chestnuts’ – thick cylinders and spheres under internal and external pressures – present results that are not easily anticipated. Thus, such analyses provide an interesting opportunity for students (and teachers) taking elementary and advanced courses in the strength of materials to explore and perhaps enhance their physical intuition
Long-range electron transfer in structurally engineered pentaammineruthenium (histidine-62) cytochrome c
In many biological processes, long-range electron transfer (ET) plays a key role. When the three-dimensional structures of proteins are accurately known, use of modified proteins and protein-protein complexes provides an experimental approach to study ET rates between two metal centers. For Ru(His)- modified proteins, the introduction of histidine residues at any desired surface location by site-directed mutagenesis opens the way for systematic investigations of ET pathways
Integrating Student Groupwork Ratings into Student Course Grades
This article reviews the rationale for groupwork projects, particularly as they apply to business-related courses. It describes some of the pedagogical issues that faculty must address and highlights inherent weaknesses, particularly in the assessment of student effort, that often occur when groupwork is required in a course. The problem of evaluating individual student’s contributions to their group is particularly troublesome given that all students do not always contribute equally to a group’s success. Faculty members normally have little to no data or observations to assist them in valuing one student’s contribution over another student’s contribution to the group’s ultimate success. The evaluation problem can be solved by gathering and using student input regarding the contributions of their peers. This, too, can be problematic if not done in a manner that requires each student to distinguish amongst the different levels of contribution provided by each of their fellow group members. A conceptual solution for solving the ‘group member contribution’ problem and a detailed methodology for implementing the solution is offered for this problem. The solution uses peer evaluations solicited from all group members as a component of each individual student’s groupwork grade. Using a web-based form, student peer assessments are gathered anonymously and are easily integrated into the faculty member’s electronic gradebook
Rhombic Patterns: Broken Hexagonal Symmetry
Landau-Ginzburg equations derived to conserve two-dimensional spatial symmetries lead to the prediction that rhombic arrays with characteristic angles slightly differ from 60 degrees should form in many systems. Beyond the bifurcation from the uniform state to patterns, rhombic patterns are linearly stable for a band of angles near the 60 degrees angle of regular hexagons. Experiments conducted on a reaction-diffusion system involving a chlorite-iodide-malonic acid reaction yield rhombic patterns in good accord with the theory.Energy Laboratory of the University of HoustonOffice of Naval ResearchU.S. Department of Energy Office of Basic Energy SciencesRobert A. Welch FoundationCenter for Nonlinear Dynamic
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