Continuous cooling transformation diagrams applicable to the heat-affected zone of HSLA-80 and HSLA-100 steels

Continuous cooling transformation (CCT) diagrams for HSLA-80 and HSLA-100 steels pertaining to fusion welding with heat inputs of 10 to 40 kJ/cm, and peak temperatures of 1000 °C to 1400 °C have been developed. The corresponding nonlinear cooling profiles and related γ → α phase transformation start and finish temperatures for various peak temperature conditions have been taken into account. The martensite start (M _s ) temperature for each of the grades and ambient temperature microstructures were considered for mapping the CCT diagrams. The austenite condition and cooling rate are found to influence the phase transformation temperatures, transformation kinetics, and morphology of the transformed products. In the fine-grain heat-affected zone (FGHAZ) of HSLA-80 steel, the transformation during cooling begins at temperatures of 550 °C to 560 °C, and in the HSLA-100 steel at 470 °C to 490 °C. In comparison, the transformation temperature is lower by 120 °C and 30 °C in the coarse-grain heat-affected zone (CGHAZ) of HSLA-80 steel and HSLA-100 steel, respectively. At these temperatures, acicular ferrite (AF) and lath martensite (LM) phases are formed. While the FGHAZ contains a greater proportion of acicular ferrite, the CGHAZ has a higher volume fraction of LM. Cooling profiles from the same peak temperature influence the transformation kinetics with slower cooling rates producing a higher volume fraction of acicular ferrite at the expense of LM. The CCT diagrams produced can predict the microstructure of the entire HAZ and have overcome the limitations of the conventional CCT diagrams, primarily with respect to the CGHAZ.     

Phase-field investigation of multicomponent diffusion in single-phase and two-phase diffusion couples

Interdiffusion in hypothetical ternary single-phase and two-phase diffusion couples are examined using a phase-field model by numerically solving the nonlinear Cahn-Hilliard and Ginzburg-Landau equations. For diffusion couples assembled with a regular single-phase solution, constant chemical mobilities were used to examine the development of concentration profiles including uphill diffusion and zero-flux plane. Zero-flux plane for a component was observed to develop for a diffusion couple at the composition that corresponds to the activity of that component in one of the terminal alloys. Experimental thermodynamic parameters and composition-dependent chemical mobilities were used to examine the morphological evolution of the interphase boundary in solid-to-solid, two-phase diffusion couples. Instability at the interphase boundary was introduced initially (t=0) by a small compositional fluctuation at the diffuse interface, and its evolution varied largely as a function of terminal alloys and related composition-dependent chemical mobility. This article was presented at the Multicomponent-Multiphase Diffusion Symposium in Honor of Mysore A. Dayananda, which was held during TMS 2006, the 135th Annual Meeting and Exhibition, March 12–16, 2006, in San Antonio, TX. The symposium was organized by Yongho Sohn of University of Central Florida, Carelyn E. Campbell of National Institute of Standards and Technology, Richard D. Sisson, Jr., of Worcester Polytechnic Institute, and John E. Morral of Ohio State University.     

Autonomous navigation for high altitude satellites

The determination of the orbit of high altitude satellites with an accurate horizontal charge coupled device (CCD) sensor is considered using the extended Kalman filter. The measurement nonlinearity is removed by using a coordinate transform, and the corresponding steady state error is less than the steady state error in the Cartesian coordinate system. The performance of both of the navigational filters is evaluated for a reference geosynchronous orbit as a function of measurement error. The reduction of measurement uncertainty decreased steady state errors in position and velocity.     

Mass classification method in mammograms using correlated association rule mining

In this paper, we present an efficient computer-aided mass classification method in digitized mammograms using Association rule mining, which performs benign–malignant classification on region of interest that contains mass. One of the major mammographic characteristics for mass classification is texture. Association rule mining (ARM) exploits this important factor to classify the mass into benign or malignant. The statistical textural features used in characterizing the masses are mean, standard deviation, entropy, skewness, kurtosis and uniformity. The main aim of the method is to increase the effectiveness and efficiency of the classification process in an objective manner to reduce the numbers of false-positive of malignancies. Correlated association rule mining was proposed for classifying the marked regions into benign and malignant and 98.6% sensitivity and 97.4% specificity is achieved that is very much promising compare to the radiologist’s sensitivity 75%.     

A Process Integration based Approach for the Analysis of an Evaporator System

A scalable new mathematical model based on the principles of Process Integration has been developed for the analysis of multiple effect evaporator (MEE) systems. It uses the concepts of stream analysis, temperature path and internal heat exchange for the formulation of the model equations. In addition to the above concepts, the model also takes into account the variable physico‐thermal properties of steam/vapor, condensate and liquor, while simulating the MEE system. The present model consists of a set of linear equations and does not present any stability or oscillation problems during solution as is generally seen in the case of models that are based on sets of nonlinear equations. The model equations are automatically generated through a computer program and the model was run for three different liquor and flow sequences to prove its utility. The results obtained are compared with published models.     

Preparation of Sn–3.5Ag nano-solder by supernatant process

The nano-scaled Sn–3.5Ag solder was prepared successfully by a supernatant process in the present study. The morphology of the nano-particle was investigated by scanning electron microscopy (SEM) and transmission electron microscopy (TEM), respectively. It was found from the SEM micrographs that the average diameter of the particle was 137 nm with a standard deviation of ±5 nm. From the TEM studies it was revealed that the particles aggregated into larger particles and the shape of the elongated particles were irregular. The composition of the alloy was also measured by an electron probe microanalyzer (EPMA) and energy dispersive spectroscopy (EDS), qualitatively and quantitatively. The eutectic element, Ag with a weight percentage of 3.5%, was found to be homogenous over all of the particles. Furthermore, the microstructure of the Sn–3.5Ag alloy was identified by X-ray diffraction. It was found that the trace element, Ag was dissolved in the matrix, a tetragonal system, without an intermetallic phase.     

Product selection in Internet business: a fuzzy approach

In this paper, we propose a methodology which helps customers buy products through the Internet. This procedure takes into account the customer's level of desire in the product attributes, which are normally fuzzy, or in linguistically defined terms. The concept of fuzzy number will be used to measure the degree of similarities of the available products to that of the customer's requirements. The degrees of similarities so obtained over all the attributes give rise to the fuzzy probabilities and hence the fuzzy expected values of availing a product on the Internet as per the customer's requirement. Attribute‐wise the fuzzy expected values are compared with those of the available products on the Internet and the product that is closest to the customer's preference is selected as the best product. The multi‐attribute weighted average method is used here to evaluate and hence to select the best product.