Missouri University of Science and Technology

About: Missouri University of Science and Technology is a education organization based out in Rolla, Missouri, United States. It is known for research contribution in the topics: Artificial neural network & Control theory. The organization has 9380 authors who have published 21161 publications receiving 462544 citations. The organization is also known as: Missouri S&T & University of Missouri–Rolla.

An approach for development of damage-free drilling of carbon fiber reinforced thermosets

Abstract: A new comprehensive approach to select cutting parameters for damage-free drilling in carbon fiber reinforced epoxy composite material is presented. The approach is based on a combination of Taguchi's experimental analysis technique and a multi-objective optimization criterion. The optimization objective includes the contributing effects of the drilling performance measures: delamination, damage width, surface roughness, and drilling thrust force. A hybrid process model based on a database of experimental results together with numerical methods for data interpolation are used to relate drilling parameters to the drilling performance measures. Case studies are presented to demonstrate the application of this method in the determination of optimum drilling conditions for damage-free drilling in BMS 8-256 composite laminate. A process map based on the results is presented as a tool for drilling process design and optimization for the investigated tool/material combination.

Influence of Air Flow on the Performance of a Dry Powder Inhaler Using Computational and Experimental Analyses

Abstract: The aims of the study are to analyze the influence of air flow on the overall performance of a dry powder inhaler (Aerolizer®) and to provide an initial quantification of the flow turbulence levels and particle impaction velocities that maximized the inhaler dispersion performance. Computational fluid dynamics (CFD) analysis of the flowfield in the Aerolizer®, in conjunction with experimental dispersions of mannitol powder using a multistage liquid impinger, was used to determine how the inhaler dispersion performance varied as the device flow rate was increased. Both the powder dispersion and throat deposition were increased with air flow. The capsule retention was decreased with flow, whereas the device retention first increased then decreased with flow. The optimal inhaler performance was found at 65 l min−1 showing a high fine particle fraction (FPF) of 63 wt.% with low throat deposition (9.0 wt.%) and capsule retention (4.3 wt.%). Computational fluid dynamics analysis showed that at the critical flow rate of 65 l min−1, the volume-averaged integral scale strain rate (ISSR) was 5,400 s−1, and the average particle impaction velocities were 12.7 and 19.0 m s−1 at the inhaler base and grid, respectively. Correlations between the device flow rate and (a) the amount of throat deposition and (b) the capsule emptying times were also developed. The use of CFD has provided further insight into the effect of air flow on the performance of the Aerolizer®. The approach of using CFD coupled with powder dispersion is readily applicable to other dry powder inhalers (DPIs) to help better understand their performance optimization.

Sequential optimization and reliability assessment for multidisciplinary systems design

Abstract: With higher reliability and safety requirements, reliability-based design has been increasingly applied in multidisciplinary design optimization (MDO). A direct integration of reliability-based design and MDO may present tremendous implementation and numerical difficulties. In this work, a methodology of sequential optimization and reliability assessment for MDO is proposed to improve the efficiency of reliability-based MDO. The central idea is to decouple the reliability analysis from MDO with sequential cycles of reliability analysis and deterministic MDO. The reliability analysis is based on the first-order reliability method (FORM). In the proposed method, the reliability analysis and the deterministic MDO use two MDO strategies, the multidisciplinary feasible approach and the individual disciplinary feasible approach. The effectiveness of the proposed method is illustrated with two example problems.

Electrochemical Synthesis and Sintering of Nanocrystalline Cerium(IV) Oxide Powders

Abstract: Nanocrystalline CeO{sub 2} powders were prepared electrochemically by the cathodic electrogeneration of base, and their sintering behavior was investigated. X-ray diffraction and transmission electron microscopy revealed that the as-prepared powders were crystalline cerium(IV) oxide with the cubic fluorite structure. The lattice parameter of the electrogenerated material was 0.5419 nm. The powders consisted of nonaggregated, faceted particles. The average crystallite size was a function of the solution temperature. It increased from 10 nm at 29 C to 14 nm at 80 C. Consolidated powders were sintered in air at both a constant heating rate of 10 C/min and under isothermal conditions. The temperature at which sintering started (750 C) for nanocrystalline CeO{sub 2} powders was only about 100 C lower than that of coarser-grained powders (850 C). However, the sintering rate was enhanced. The temperature at which shrinkage stopped was 200--300 C lower with the nanoscale powder than with micrometer-sized powders. A sintered specimen with 99.8% of theoretical density and a grain size of about 350 nm was obtained by sintering at 1,300 C for 2 h.