Shape Factor Effect on Inclusion Sedimentation in Aluminum Melts

Metallurgical and Materials Transactions B - The quality requirements of aluminum products are steadily increasing, and the presence of non-metallic inclusions have a large impact on the quality of...     

Detailed Loop Model (DLM) analysis of liquid solar thermosiphons with heat exchangers

An analytical Detailed Loop Model (DLM) has been developed to analyze the performance of solar thermosiphon water heaters with heat exchangers in storage tanks. The model has been used to study the performance of thermosiphons as a function of heat exchanger characteristics, heat transfer fluids, flow resistances, tank stratification, and tank elevation relative to the collector. The results indicate that good performance can be attained with these systems compared to thermosiphons without heat exchangers.     

Effects of geometry and PVP addition on mechanical behavior of PEI membranes for use in wastewater treatment

This study focuses on the mechanical behavior and design of membrane filters that are used in water and wastewater treatment. The aim of this study is, after characterizing the mechanical behavior of the membrane materials, to find a better shape in terms of mechanical parameters. As the first step, uniaxial tensile testing is applied to the produced polymeric membranes with certain contents of poly(ether imide), poly(vinylpyrrolidone), and N-methyl-2-pyrrolidone to get an understanding of the mechanical behavior of the membrane materials. The material data obtained from this experimental process are used as input to software where a finite element model of the membrane is built. Each geometry has the same boundary conditions and the same area, and the same pressure is applied to each geometry. Using these numerical models, the selected geometries are analyzed in terms of displacement, equivalent stress, and equivalent strain. The results are discussed based on these parameters. © 2018 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2019 , 136, 47073.     

The predicted impact of roof aperture design on the energy performance of office buildings

An investigation has been made of potential lighting electricity reductions and associated thermal impacts of replacing electric light with sunlight admitted through rooftop glazing on a single-story, prototypical office building. Experimental scale models have been used to determine the fraction of the solar radiation entering the aperture which reaches the work plane as useful illumination. This information is used in a developmental version of the building energy analysis computer program BLAST-3.0 to predict reductions in lighting electricity and the impacts on energy consumption for heating and cooling the building. The results indicate that a large fraction of the electricity consumed for lighting a single-story office building can be displaced using modest amounts of glazing in the roof. Also, both heating and cooling energy consumption reductions are possible from a daylighting system, but they are substantially smaller than the potential lighting electricity reductions. The design implications of the results are discussed and future directions for the work are outlined.     

Application of the Taguchi method to chip scale package (CSP)design

A three-dimensional (3-D) nonlinear finite element model of an overmolded chip scale package (CSP) on flex-tape carrier has been developed by using ANSYS^TM finite element simulation code. The model has been used to optimize the package for robust design and to determine design rules to keep package warpage within acceptable Joint Electron Device Engineering Council (JEDEC) limits. An L₁₈ Taguchi matrix has been developed to investigate the effect of die thickness and die size, mold compound material and thickness, flex-tape thickness, die attach epoxy and copper trace thicknesses, and solder bail collapsed stand-off height on the reliability of the package during temperature cycling. For package failures, simulations performed represent temperature cycling 125°C to -40°C. This condition is approximated by cooling the package which is mounted on a multilayer printed circuit board (PCB) from 125°C to -40°C. For solder ball coplanarity analysis, simulations have been performed without the PCB and the lowest temperature of the cycle is changed to 25°C. Predicted results indicate that for an optimum design, that is low stress in the package and low package warpage, the package should have smaller die with thicker overmold. In addition to the optimization analysis, plastic strain distribution on each solder ball has been determined to predict the location of solder ball with the highest strain level. The results indicate that the highest strain levels are attained in solder balls located at the edge of the die. The strain levels could then be used to predict the fatigue life of individual solder balls