Using neural networks to select wavelet features for breast cancerdiagnosis

This study focuses on improving microcalcification classification by establishing an efficient computer-aided diagnosis system that extracts Daubechies-4 and biorthogonal wavelet features. These wavelets were chosen because they have been used in military target recognition and fingerprint recognition research with images characterized by low contrast, similar to mammography. Feature selection techniques are employed to further increase classification performance. The artificial neural network feature selection techniques are complemented by a conventional decision boundary-based feature selection method. The results using the wavelet features are compared to more conventional measures of image texture, angular second moment, and Karhunen Loeve coefficients. The use of alternative signal processing to compare wavelet and neural techniques allows for a measure of the problem difficulty. It is concluded that advances and contributions have been made with the introduction of two novel feature extraction methods for breast cancer diagnosis, wavelets and eigenmasses. Additionally, feature selection techniques are demonstrated, compared, and validated, transforming adequate discrimination power into promising classification results     

Direct synthesis and characterization of the Fe3+ analogue of Naβ″-alumina

A new isomorphic analogue of-alumina, a potassium-free Na-ferrite (Na₂O · 5 (Al_0.10Fe_1.90)O₃, referred to as Na-ferrite), has been synthesized and is characterized using X-ray powder and single crystal diffraction, wet chemical analysis, and transmission electron microscopy (TEM). In addition, Na-aluminate-gallate-ferrate phases were also successfully synthesized, but were not characterized in detail. Na-ferrite grew in a slowly cooling melt or partial melt from 1250° C in air using Na₂CO₃ and Fe₃O₄ (magnetite) as starting materials. The compound was also synthesized using-Fe₂O₃ instead of Fe₃O₄ under the same conditions, but its abundance was much less and-Fe₂O₃ and NaFeO₂ were the dominant phases. The new material (cell dimensionsa = 0.5955,c = 3.5623 nm) is reversibly hygroscopic, andc increases 2% after hydration. TEM images dearly show the 1.19 nm lattice spacing corresponding to the ionic conduction planes, and these planes are observed to be both straight and curled. The origin of the curled lattice planes, the existence of which is also evident in the single crystal precession photographs, is not clear, although we believe it may involve a structural misfit between the ferric oxide spineI block and soda layer.     

Growth of part-through thickness fatigue cracks in sheet polymethylmethacrylate

Fatigue growth data has been obtained for part-through thickness cracks in sheet specimens of polymethylmethacrylate subjected to cyclic tension. Statistical techniques are used to examine the usefulness of linear elastic fracture mechanics for correlating this part-through thickness crack growth data with throughthickness data published previously.     

Electrochemical determination of rusted steel surface stability

The stability of a rusted steel surface exposed to a 0.11 M sodium sulphate solution has been studied. Electrochemical impedance spectroscopy, polarization resistance and atomic absorption analysis techniques were used in conjunction with mild steel specimens rusted in a rural atmosphere and treated with different concentrations of phosphoric acid. Since most of the impedance diagrams obtained differ from the typical semicircle, it is not clear how to obtain kinetic information on the corrosion process. The polarization resistance technique gives more useful data.     

Abrasion Resistance of Field-Assisted Ion-Exchanged Glass

The fracture strength of HF-etched samples was measured as a function of field-assisted K-Na ion exchange depth, as well as the severity of abrasion. As expected, the more severe the abrasion, the greater the depth required to make the strength insensitive to abrasion. An abrasion-independent weakening mechanism that increased with exchange depth was also found to be operative.     

Toughening by Metallic Lamina in Nickel/Alumina Composites

Tape casting and hot-pressing were used to produce metal/ alumina laminate composites. The mechanical behavior of these laminates was characterized. The strength and toughness of the laminates were greatly improved in comparison to that of monolithic alumina. Indentation strength values of the laminates remained approximately constant for indent loads between 10 and 100 N. Thus, this type of laminate appears to be a good candidate for damage-tolerant composite material design.     

Structural Aspects of the Lattice Thermal Expansion of Hexagonal Cordierite

The mechanism of lattice thermal expansion in pure hexagonal cordierite prepared by glass devitrification was investigated by time-of-flight neutron powder diffraction at temperatures from 22° to 750°C under vacuum. Full matrix least-squares refinement of the diffraction spectra was carried out in space group P6/mcc using the Rietveld method. The structural data from the refinements were resolved into components parallel and normal to the c axis. The negative c axis expansion results from two effects: (1) increasing distortion of the T₂ tetrahedral (ring tetrahedra) with temperature, primarily due to displacement of the T₂ cations toward the c-axis channels in the structure; (2) decreasing distortion of the T₁/M tetrahedra/ octahedra with increasing temperature, due to octahedral I (M-O₁) bond expansion and an associated decrease in torsional distortion of the T₁ tetrahedra.     

Processing and Properties of Particulate Composites from Coated Powders

A method is described for sintering of highly loaded (≤20 vol%) alumina matrix/silicon carbide whisker or platelet composites to closed porosity. The method uses controlled heterogeneous precipitation in a suspension of whiskers or platelets. The suspension-coated particles are calcined to produce a free-flowing composite powder which can be hot-pressed or free-sintered to high density. The results of consolidation and mechanical property testing are reported.     

Suitability of commercial cottonseed for producing edible high protein flours by liquid classification

The 1976 and 1977 crops of glanded cottonseed from oil mills located in 7 major U.S. cottonbelt growing areas were evaluated as to their suitability for processing into edible, high-protein flours. Both the physical and chemical characteristics of fuzzy seed samples were studied. Ginned seed samples were hulled, dried, comminuted, slurried with hexane and liquid classified by both a laboratory differential settling test (DST) and pilot plant liquid cyclone process (LCP). Liquid cyclone operating data and extensive analytical data of the kernels, flour and meals produced are shown. A free gossypol level of 1.10% or less in full fat kernels was the determining factor for producing edible flours from glanded seed by the LCP. The Lower Rio Grande Valley area was the only area from which liquid classified cottonseed flour consistently exceeded the current maximal free gossypol standard of 450 ppm. Ca. 94% of the total U.S. cottonseed production is suitable for producing edible, high-protein flours by liquid classification.