An Engineering Learning Community To Promote Retention And Graduation Of At-Risk Engineering Students

Retention and graduation rates for engineering disciplines are significantly lower than desired, and research literature offers many possible causes. Engineering learning communities provide the opportunity to study relationships among specific causes and to develop and evaluate activities designed to lessen their impact. This paper details an engineering learning community created to combat three common threats to academic success of engineering students: financial difficulties, math deficiencies, and the lack of a supportive engineering culture. The project tracks participants in the learning community from first year through graduation to assess the effectiveness of its activities in improving retention and graduation rates. Scholarships were made available to address the financial difficulties; tutors, mentors, study groups, and a “freshman-to-sophomore bridge” summer program were provided to address math deficiencies; cohort engineering courses, active learning techniques, required group meetings, required group study sessions, dedicated study space, and dedicated faculty advisors were used to promote a sense of community. Quantitative retention and graduation rates for the cohort are compared to other engineering groups at the same institution. Qualitative results collected via student surveys and interviews, and lessons learned by project administrators are also presented. Retention and graduation rates of the cohort are better than those of comparable groups at the same institution. Graduation rates based upon freshman math placement are also higher than comparable groups.

Uniaxial Tensile Properties of AS4 3D Woven Composites with Four Different Resin Systems: Experimental Results and Analysis: Property Computations

As a part of the NASA Composite Technology for Exploration project, eight different AS4 3D orthogonal woven composite panels were manufactured and were subjected to mechanical testing including uniaxial tension along the weaves' warp direction. Each set, with four different resin systems (KCR-IR6070, EP2400, RTM6, and RS-50), included weave architectures designed using 12K and 6K AS4 carbon fiber yarns. For the tension testing conducted at Room Temperature Ambient (RTA) conditions, the elastic modulus and strength of these eight panels (as-processed and thermally-cycled) were measured and compared while the potential evolution of micro-cracking before and after thermal cycling were monitored via optical microscopy and X-Ray Computed Tomography. The data set also included test results of the as-processed materials at Elevated Temperature Wet (ETW) conditions. In the second part of this study, efforts were made to compute elastic constants for AS4 6K/RTM6 and AS4 12K/RTM6 materials by implementing a finite element approach and the Multiscale Generalized Method of Cells (MSGMC) technique developed at NASA Glenn Research Center. Digimat-FE was used to model the weave architectures, assign properties, calculate yarn properties, create the finite element mesh, and compute the elastic properties by applying periodic boundary conditions to finite element models of each repeating unit cell. The required input data for MSGMC was generated using Matlab from Digimat exported weave information. Experimental and computational results were compared, and the differences and limitations in correlating to the test data were briefly discussed

SADL: Simulation Architecture Description Language

This paper introduces the Simulation Architecture Description Language (SADL) developed at the National Aeronautics and Space Administration's Marshall Space Flight Center to support the real-time simulation of advanced avionics systems. SADL is a graphical, domain-specific Architecture Description Language (ADL) that facilitates the high-level specification of both the software and hardware aspects of hard real-time avionics system simulations targeted for execution on diverse hardware architectures, including multiprocessor systems. It supports the hierarchical expression of the architecture of an entire simulation at various levels of abstraction. A detailed description of SADL is provided along with a case study that illustrates its ability to represent real-world simulations. Key words: Architecture Description Language, real-time, simulation, software architecture, simulation model

Abstract Quaternary Arithmetic Logic Unit on a Programmable Logic Device

Common binary arithmetic operations such as addition/subtraction and multiplication suffer from O(n) carry propagation delay where n is the number of digits. Carry lookahead helps to improve the propagation delay to O(log n), but is bounded to a small number of digits due to the complexity of the circuit. A carry-free arithmetic operation can be achieved using a higher radix number system such as Quarternary Signed Digit (QSD). In QSD, each digit can be represented by

Wells/RickB. eir -- IEEE Transac9PX< on Aerospac andElec> onic Systems -- Vol. 33, No. 2, pp. 507-523,,April 1997.

This paperdesc9=>F theapplicL9z= of newly-developed parallel procP=<>= tec hniques that exploit the irregularly-strucc edfunc<H9z= parallelism present within a test-bed aerospac system (i.e. aspac shuttle main roc ket engine simulation) utilizing a reducP cucP xity multiclti -9L= arc hitecKX e with an arbitrary topology. The methodologies areapplicz== to real time parallel simulation of large-sc<F dynamic systems andinc>=L deterministic model optimization anddecHXXX9zKML tec hniques, automated translationmec hanisms, and a newly-developed task allocF<M9 heuristic The effecK<<9zKP of thesetec hniques are illustrated withperformanc being measuredempiriczK< for a wide range of topologicl cclo9 ations using a partially recHX=M urable network of Transputers. Wells/RickB. eir -- IEEE Transac9PX< on Aerospac andElec> onic Systems -- Vol. 33, No. 2, pp. 507-523,,April 1997