Spartan Release Engagement Mechanism (REM) stress and fracture analysis

The revised stress and fracture analysis of the Spartan REM hardware for current load conditions and mass properties is presented. The stress analysis was performed using a NASTRAN math model of the Spartan REM adapter, base, and payload. Appendix A contains the material properties, loads, and stress analysis of the hardware. The computer output and model description are in Appendix B. Factors of safety used in the stress analysis were 1.4 on tested items and 2.0 on all other items. Fracture analysis of the items considered fracture critical was accomplished using the MSFC Crack Growth Analysis code. Loads and stresses were obtaind from the stress analysis. The fracture analysis notes are located in Appendix A and the computer output in Appendix B. All items analyzed met design and fracture criteria

Materials properties, loads, and stress analysis, Spartan REM: Appendix A

The mechanical properties, load tests, and stress analysis of the Spartan Release Engagement Mechanism (REM) is presented. The fracture properties of the components of the unit are also discussed. Detailed engineering drawings are included

Antipointing Adherence to Fitts\u27 Equation is Amplitude-Dependent

Goal-directed reaches performed with spatial overlap between stimulus and response (i.e., propointing) are supported by dedicated visuomotor networks that provide absolute visual information for movement planning and control. Furthermore, propointing adheres to speed-accuracy relations as defined by Fitts\u27 equation such that movement time (MT) is predicted by the log/linear relationship between movement amplitude and target width. It is, however, unknown whether reaches with dissociable spatial relations between stimulus and response adhere to Fitts\u27 law. To that end, I examined whether antipointing (i.e., reaching mirror-symmetrical to a target) adheres to Fitts\u27 equation in the same vein as propointing. Results showed that propointing MTs adhered to Fitts’ equation, whereas antipointing adherence was amplitude-dependent. Further, that the deceleration phase of antipointing responses did not scale to IDFittssuggests a mode of control (i.e., offline) distinct from their propointing counterparts

The SPAR thermal analyzer: Present and future

The SPAR thermal analyzer, a system of finite-element processors for performing steady-state and transient thermal analyses, is described. The processors communicate with each other through the SPAR random access data base. As each processor is executed, all pertinent source data is extracted from the data base and results are stored in the data base. Steady state temperature distributions are determined by a direct solution method for linear problems and a modified Newton-Raphson method for nonlinear problems. An explicit and several implicit methods are available for the solution of transient heat transfer problems. Finite element plotting capability is available for model checkout and verification

Polynomial-time computability of the edge-reliability of graphs using Gilbert's formula

Reliability is an important consideration in analyzing computer and other communication networks, but current techniques are extremely limited in the classes of graphs which can be analyzed efficiently. While Gilbert's formula establishes a theoretically elegant recursive relationship between the edge reliability of a graph and the reliability of its subgraphs, naive evaluation requires consideration of all sequences of deletions of individual vertices, and for many graphs has time complexity essentially Θ (N!). We discuss a general approach which significantly reduces complexity, encoding subgraph isomorphism in a finer partition by invariants, and recursing through the set of invariants

The Role of Transformative Learning in Fostering Identity Development among Learners in Professional Education Programs of Study

This roundtable discussion engages participants in exploring how professional identity develops for learners engaged in advanced professional education and how they experience the meaning of what it is to become a professional

Uncertainty Analysis for the Evaluation of a Passive Runway Arresting System

This paper considers the stopping distance of an aircraft involved in a runway overrun incident when the runway has been provided with an extension comprised of a material engineered to induce high levels of rolling friction and drag. A formula for stopping distance is derived that is shown to be the product of a known formula for the case of friction without drag, and a dimensionless constant between 0 and 1 that quantifies the further reduction in stopping distance when drag is introduced. This additional quantity, identified as the Drag Reduction Factor, D, is shown to depend on the ratio of drag force to friction force experienced by the aircraft as it enters the overrun area. The specific functional form of D is shown to depend on how drag varies with speed. A detailed uncertainty analysis is presented which reveals how the uncertainty in estimates of stopping distance are influenced by experimental error in the force measurements that are acquired in a typical evaluation experiment conducted to assess candidate overrun materials