196,030 research outputs found
Brazed Borsic/aluminum structural panels
No full textA fluxless brazing process has been developed that minimizes degradation of the mechanical properties of Borsic/aluminum composites. The process, which employs 718 aluminum alloy braze, is being used to fabricate full scale Borsic/aluminum-titanium honeycomb-core panels for Mach 3 flight testing on the YF-12 aircraft and ground testing in support of the Supersonic Cruise Aircraft Research (SCAR) Program. The manufacturing development and results of shear tests on full scale panels are presented
Fabrication and evaluation of brazed titanium-clad Borsic/aluminum compression panels
No full textProcesses for brazing Borsic/aluminum composite materials that eliminate diffusion of braze alloy constituents into the aluminum matrix developed. One brazing study led to the development of a hybrid composite which combines high strength Borsic/aluminum and ductile titanium to form a material identified as titanium clad Borsic/aluminum. The titanium foil provides the Borsic/aluminum with a durable outer surface and serves as a diffusion barrier which alleviates fiber and matrix degradation during brazing. Titanium clad Borsic/aluminum skin panels were joined to titanium clad Borsic/aluminum stringers by brazing and were tested in end compression at room and elevated temperatures. The data include failure strength, buckling strength, and the effects of brazing on the material properties. Predicted buckling loads are compared with experimental data
Whole-System Electromagnetic Modeling for Microwave Tomography
No full textThis letter presents a full-wave, whole-system modeling of microwave imaging tomography (MWT) systems to be used as the forward model in reconstruction (inverse) algorithms. The full geometry including antennas and their ports is simulated via a finite element method (FEM) approach. A new technique is used to compute the antenna operation in the system, which provides a general method to enforce the excitation as a specific modal distribution and to extract the voltage and current from the employed antenna. We report results for a complete microwave imaging (MWI) system with comparison between measured and simulated dat
Effects of fabrication and joining processes on compressive strength of boron/aluminum and borsic/aluminum structural panels
No full textProcesses for forming and joining boron/aluminum and borsic/aluminum to themselves and to titanium alloys were studied. Composite skin and titanium skin panels were joined to composite stringers by high strength bolts, by spotwelding, by diffusion bonding, by adhesive bonding, or by brazing. The effects of the fabrication and joining processes on panel compressive strengths were discussed. Predicted buckling loads were compared with experimental data
Fabrication and evaluation of brazed titanium-clad borsic/aluminum skin-stringer panels
No full textA successful brazing process was developed and evaluated for fabricating full-scale titanium-clad Borsic/aluminum skin-stringer panels. A panel design was developed consisting of a hybrid composite skin reinforced with capped honeycomb-core stringers. Six panels were fabricated for inclusion in the program which included laboratory testing of panels at ambient temperatures and 533 K (500 F) and flight service evaluation on the NASA Mach 3 YF-12 airplane. All panels tested met or exceeded stringent design requirements and no deleterious effects on panel properties were detected followng flight service evaluation on the YF-12 airplane
Mechanical property characterization of Borsic/aluminum laminates at room and elevated temperatures
No full textSix Borsic/aluminum laminate orientations exposed to a braze temperature cycle were tested in tension, compression, and shear to determine tangent modulus, maximum stress and strain, and Poisson's ratio of the laminates at room and elevated temperatures. Mechanical properties in tension were determined from flat tensile and sandwich beam tests. Room temperature flat tensile tests were performed on laminates in the as-received condition to compare with specimens exposed to a braze temperature cycle. Sandwich beam tests were also used to determine mechanical properties in compression. Shear properties were determined from biaxially loaded, picture frame shear specimens. Results are presented by using functional relations between stress and strain and tangent modulus and strain, and in tables by indicating maximum stress and strain and Poisson's ratio
Dr. Duane M. Jackson, Morehouse College, July 2011
No full textThis video is a conversation with Dr. Duane M. Jackson. Dr. Jackson talks about his paper, "Recall and the Serial Position Effect: The Role of Primacy and Recency on Accounting Students' Performance." Jackie Daniel, AUC Woodruff Library, is the interviewer
"Reflections on the subject of Emigration from Europe with a view to Settlement in the United States" By M. Carey.
No full text"Reflections on the subject of Emigration from Europe with a view to Settlement in the United States: containing bried sketches of the moral and political character of those states.
By M. Carey, member of the American philosophical, and of the American Antiquarian Society, and author of The Olive Branch, Cindiciae Hibernicae, essays on banking, on political economy, and on internal improvement.
To which are now added the English editor's comments on the subject; together with Important Advice to Emigrants, and Cautions Against Impositions Practiced in the Outports
Dispelling the Myths Behind First-author Citation Counts
No full textWe conducted a full-scale evaluative citation analysis study of scholars in the XML research field to explore just how different from each other author rankings resulting from different citation counting methods actually are, and to demonstrate the capability of emerging data and tools on the Web in supporting more realistic citation counting methods. Our results contest some common arguments for the continued
use of first-author citation counts in the evaluation of scholars, such as high correlations between author rankings by first-author citation counts and other citation
counting methods, and high costs of using more realistic citation counting methods that are not well-supported by the ISI databases. It is argued that increasingly available digital full text research papers make it possible for citation analysis studies to go beyond what the ISI databases have directly supported and to employ more
sophisticated methods
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