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Background: Measurement of local stress amplitude at the stress concentration point is a key component of mechanical design from the viewpoint of preventing metal fatigue. Copper electroplating method, which is a stress measurement method utilizing grains grown in a copper foil by cyclic loading, is suitable for such microscopic stress measurement. Reports have shown that the maximum shear stress and principal stress, which are important components in the evaluation of fatigue strength, can be measured by examining the density and crystallographic features of grown grains. Objective: Electron backscatter diffraction (EBSD) analysis of grown grains can be utilized to understand the crystallographic features of the grains, but EBSD equipment requires technical skill to operate, which makes it inconvenient. In this paper, we explore the feasibility of stress measurement by analyzing the crystallographic features of grown grains using the X-ray diffraction (XRD) method, which is more versatile than the EBSD method. Methods: Cyclic loading tests were conducted using smooth specimens with copper foil adhered under various biaxial stress conditions of bending and torsion. The surfaces of the grains-grown copper foil were then analyzed by the XRD method. Results: The peak of diffraction intensity tended to shift from the (220) plane to the (111) plane as the biaxial stress ratio increased. We quantified this tendency using the Lotgering factor and developed an empirical formula for determining the relationship between the Lotgering factor and the biaxial stress ratio. Conclusions: Our proposed empirical formula enables principal stress measurement within a biaxial stress ratio C ranging from –0.45 to 0, and the measurement accuracy is comparable to that of the conventional EBSD method. [ABSTRACT FROM AUTHOR]

Structural refinement by cold rolling (10 to 80 pct reductions) of interstitial free (IF) steel containing Mn and B has been investigated from samples with different initial structures: (a) lath martensite, (b) coarse ferrite (grain size 150 μm), and (c) fine ferrite (22 μm). Unalloyed IF steel with a coarse grain size (120 μm) has also included based on a previous study. Deformation microstructures and structural parameters have been analyzed by transmission electron microscopy and electron backscatter diffraction, and mechanical properties have been characterized by hardness and tensile testing. At low to medium strains, lath martensite transforms into a cell block structure composed of cell block boundaries and cell boundaries with only a negligible change in strength. At medium to large strains, cell block structures in all samples refine with increasing strain and the hardening rate is constant (stage IV). A strong effect of the initial structure is observed on both the structural refinement and the strength increase. This effect is largest in lath martensite and smallest in unalloyed ferrite. No saturation in structural refinement and strength is observed. The discussion covers the transformation of lath martensite into a cell block structure at low to medium strains where the driving force is suggested to be a decrease in the dislocation line energy. Medium to large strain-hardening mechanisms are discussed together with structure-strength relationships assuming additive stress contributions from dislocations, boundaries, and elements in solid solution. Good agreement is found between flow stress predictions and stress values observed experimentally both in the initial undeformed martensite and in deformed samples. [ABSTRACT FROM AUTHOR]

Optical emission signals of a dc arc plasma system that was used for generating ZnO nanoparticles (NPs) have been investigated in gas phase as a function of chamber pressure and arc current. In this technique, a commercially available zinc 4N rod is used as a zinc source, as well as anode in the dc circuit and ambient air as an oxygen source. A carbon rod acts as the cathode. The optical transitions of Zn(I) and O(I) in addition, excitation of high energy states of N, CN, and atomic nitrogen lines were observed in OES due to increase of electron temperature than gas temperature ( T > T) by reducing the chamber pressure from 760 torr to lower pressures. The as-prepared NPs show good crystalline quality with hexagonal wurtzite structure and the particle size was ranging from few nm to 100 nm in the form of rod and spherical morphologies. The impurity nature and structural properties of as-prepared NPs by dc arc plasma experiments were correlated with OES and Raman spectroscopy. [ABSTRACT FROM AUTHOR]

A cyclic biaxial stress measurement method using electrodeposited copper foil was examined. The crystallographic orientations of individual grains that undergo grain growth in copper foil subjected to cyclic loading were analyzed by electron backscatter diffraction (EBSD). One of the slip directions in most of the grains corresponded to the direction of maximum shear stress when the biaxial stress ratio was negative. However, the number of grains with other orientations gradually increased as the biaxial stress ratio approached zero. On the basis of these features, we propose biaxial stress measurement using EBSD analysis of grown grains in copper foil. Our new method has excellent resolution compared with other stress-strain measurement methods since it can measure the average biaxial stress ratios in an area of 500 μm × 500 μm. [ABSTRACT FROM AUTHOR]

The effects of deformation temperature on texture and thermoelectric properties of p-type BiSbTe sintered materials were investigated. The sintered materials were prepared by mechanical alloying and hot-press sintering. The hot-press deformation was performed at 723 K and 823 K by applying mechanical pressure in a graphite die. Then, the materials were extruded in the direction opposite to the direction of applied pressure. X-ray diffraction and electron backscattered diffraction patterns showed that the hexagonal c-plane tended to align along the extruded direction when the samples were deformed at high temperatures. The thermoelectric power factor was increased by high-temperature hot-press deformation because of the low electrical resistivity that originated from the c-plane orientation. [ABSTRACT FROM AUTHOR]

A common problem frequently faced by business firms and individual investors is to select a few investment opportunities from many available possibilities. This problem, in its simplest form, can be modeled as a O-l knapsack problem. In a more general investment scenario, however, we obtain a model which is a general knapsack problem with a multiple-choice constraint. To solve this problem, an efficient enumerative algorithm is developed. The algorithm includes an efficient procedure to solve the LP-relaxed problem, a reduction algorithm which may allow the initial fixing of some of the variables, and various other implicit enumeration criteria derived from the group problem. Extensive computational experience illustrates the efficiency of the algorithm and related results. [ABSTRACT FROM AUTHOR]