Selected On-Demand Medical Applications of 3D-Printing for Long-Duration Manned Space Missions

Recent technological advances in the area of Additive Manufacturing (i.e. 3D printing) allow for exploration of their use within long-duration manned space missions. Among the many potential application domains, medical and dental fabrication in support of crew health is of interest to NASA’s Advanced Exploration Systems directorate. A classification of medical events with their associated response timeline discern between those applications where current 3D printing technologies can provide adequate support. Products and devices that require on-demand fabrication (due to the high level of personal customization) but that can wait for a reasonable (e.g. few hours) fabrication time are the most promising areas. Among these non-emergency, on-demand applications, two were identified for further investigation: dental health and pharmaceutical drugs. A discussion on the challenges presented by a microgravity operational environment on these technologies is provided

Development Of Master’s Programs In Sustainable Engineering

During the 2006-2007 academic year, a team of faculty from the Kate Gleason College of Engineering developed a proposal for a pair of Master’s programs (a Master of Science program and a Master of Engineering proposal) in the field of Sustainable Engineering. Sustainable Engineering has been described as “engineering for human development that meets the needs of the present without compromising the ability of future generations to meet their own needs” [3]. Both programs are multidisciplinary in nature and include coursework from the disciplines of Industrial and Systems Engineering, Mechanical Engineering, Civil Engineering Technology, and Public Policy. The programs offer students the flexibility to develop ‘tracks’ in their program of study which would permit deeper immersion in domains such as renewable energy systems, systems modeling and analysis, product design, etc. Student interest in the programs has been very favorable. This paper describes the context at RIT from which the idea for these programs arose, the program development process that was followed, and the structure of the two programs

Geometric Modeling of Engineered Abrasive Processes

One of the common issues that arises in abrasive machining is the inconsistency of the surface roughness within the same batch and under identical machining conditions. Recent advances in engineered abrasives have allowed replacement of the random arrangement of minerals on conventional belts with precisely shaped structures uniformly cast directly onto a backing material. This allows for abrasive belts that are more deterministic in shape, size, distribution, orientation, and composition. A computer model based on known tooling geometry was developed to approximate the asymptotic surface profile that was achievable under specific loading conditions. Outputs included the theoretical surface parameters, R^sub q^, R^sub a^, R^sub v^, R^sub p^, R^sub t^, and R^sub sk^. Experimental validation was performed with a custom-made abrader apparatus and using engineered abrasives on highly polished aluminum samples. Interferometric microscopy was used in assessing the surface roughness. Results include the individual effects of pyramid base width, pyramid height, attack angle, and indentation depth on the surface descriptors

Design, Implementation, And Integration Of An Experiential Assembly System Engineering Laboratory Module

Curriculum integration and multidisciplinary studies have become key issues in improving engineering education. This paper presents the design and implementation of laboratory material that integrates three traditionally independent courses in the industrial engineering curriculum, manufacturing, ergonomics, and simulation, utilizing an experiential assembly system. This collaborative project incorporates a team-based learn-by-doing approach to the theoretical knowledge in these subject areas1,3. These components are implemented in a dynamic and reconfigurable environment in which the students are given the opportunity of contrasting his/her design against the working reality. The results of this project are discussed along with the impact on the curriculum

An MIP Approach to the U-line Balancing Problem With Proportional Worker Throughput

One of the major challenges faced by manufacturing companies is to remain competitive in dynamic environments, where fluctuations in customer demand and production rates require systems capable of adapting in a practical and economical way. A U-shaped production cell is considered one of the most flexible designs for adapting the workforce level to varying conditions. However, re-balancing efforts are time consuming and often require a new work allocation and line design. In this paper, a two-stage MIP model to determine the best cell design under varying workforce levels is proposed. The model seeks to maintain proportionality between throughput and the number of workers. Computational experiments considering various line configurations (up to 19 stations) and workloads (up to 79 tasks) are performed. The results show the proposed algorithm provides excellent results for all small and medium size problems addressed in this study, as well as for certain configurations of large problems. This approach can be used to generate lookup tables of line designs to help with quick reallocation of worker assignments on the shop floor and with minimal disruption

Modeling of Tooling-Workpiece Interactions on Random Surfaces

Abrasive processes, commonly employed in manufacturing, are difficult to model because they rely on brittle particles with unknown geometry and multiple points of contact. Newly developed microreplicated abrasives allow for control of abrasive grit properties such as size, shape, and distribution. This paper proposes and validates a parametric model of abrasive machining that allows for studying the interaction of this particular tooling with randomly generated surfaces. In this work, the parameters of a probability distribution function that represents the workpiece surface are approximated by profilometry data. Monte Carlo simulation is used to account for inter- and intraspecimen variability. A geometric representation is used to mathematically represent the interaction between workpiece and tool. The results show good correlation between theoretical and actual values. This approach could be used to aid in tool geometry design as well as in process parameter optimization

Analysis of very-high surface area 3D-printed media in a moving bed biofilm reactor for wastewater treatment

Moving Bed Biofilm Reactors (MBBRs) can efficiently treat wastewater by incorporating suspended biocarriers that provide attachment surfaces for active microorganisms. The performance of MBBRs for wastewater treatment is, among other factors, contingent upon the characteristics of the surface area of the biocarriers. Thus, novel biocarrier topology designs can potentially increase MBBR performance in a significant manner. The goal of this work is to assess the performance of 3-D-printed biofilter media biocarriers with varying surface area designs for use in nitrifying MBBRs for wastewater treatment. Mathematical models, rendering, and 3D printing were used to design and fabricate gyroid-shaped biocarriers with a high degree of complexity at three different levels of specific surface area (SSA), generally providing greater specific surface areas than currently available commercial designs. The biocarriers were inoculated with a nitrifying bacteria community, and tested in a series of batch reactors for ammonia conversion to nitrate, in three different experimental configurations: constant fill ratio, constant total surface area, and constant biocarrier media count. Results showed that large and medium SSA gyroid biocarriers delivered the best ammonia conversion performance of all designs, and significantly better than that of a standard commercial design. The percentage of ammonia nitrogen conversion at 8 hours for the best performing biocarrier design was: 99.33% (large SSA gyroid, constant fill ratio), 94.74% (medium SSA gyroid, constant total surface area), and 92.73% (large SSA gyroid, constant biocarrier media count). Additionally, it is shown that the ammonia conversion performance was correlated to the specific surface area of the biocarrier, with the greatest rates of ammonia conversion (99.33%) and nitrate production (2.7 mg/L) for manufactured gyroid biocarriers with a specific surface area greater than 1980.5 m2/m3. The results suggest that the performance of commercial MBBRs for wastewater treatment can be greatly improved by manipulation of media design through topology optimization

Characterization of Surface Roughness Effects on Pressure Drop in Single-Phase Flow in Minichannels

Roughness features on the walls of a channel wall affect the pressure drop of a fluid flowing through that channel. This roughness effect can be described by (i) flow area constriction and (ii) increase in the wall shear stress. Replotting the Moody\u27s friction factor chart with the constricted flow diameter results in a simplified plot and yields a single asymptotic value of friction factor for relative roughness values of e/ D\u3e 0.03 in the fully developed turbulent region. After reviewing the literature, three new roughness parameters are proposed (maximum profile peak height Rp, mean spacing of profile irregularities Rsm, and floor distance to mean line F1,). Three additional parameters are presented to consider the localized hydraulic diameter variation (maximum, minimum, and average) in future work. The roughness e is then defined as Rp+ Fp,. This definition yields the same value of roughness as obtained from the sand-grain roughness [H. Darcy, Recherches Experimentales Relatives au Mouvement de L\u27Eau dans les Tuyaux (Mallet-Bachelier, Paris, France, 1857); J. T. Fanning, A Practical Treatise on Hydraulic and Water Supply Engineering (Van Nostrand, New York, 1877, revised ed. 1886); J. Nikuradse, Laws of flow in rough pipes [ Stromungsgesetze in Rauen Rohren, VDI-Forschungsheft 361 (1933)]; Beilage cu Forschung auf dens Gebiete des Ingenieurwesens, Ausgahe B Band 4. English translation NACA Tech. Mem. 1292 (1937)]. Specific experiments are conducted using parallel sawtooth ridge elements, placed normal to the flow direction, in aligned and offset configurations in a 10.03 mm wide rectangular channel with variable gap (resulting hydraulic diameters of 325 um-1819 um with Reynolds numbers ranging from 200 to 7200 for air and 200 to 5700 for water). The use of constricted flow diameter extends the applicability of the laminar friction factor equations to relative roughness values (sawtooth height) up to 14%. In the turbulent region, the aligned and offset roughness arrangements yield different results indicating a need to further characterize the surface features. The laminar to turbulent transition is also seen to occur at lower Reynolds numbers with an increase in the relative roughness

A Measurement Tool for Circular Economy Practices: A Case Study in Pallet Supply Chains

A circular economy (CE) is an economic system where products and services are traded in closed loops or ‘cycles’. This work develops a framework for assessing the extent to which product supply chains incorporate circular economy principles, and applies this framework to a specific material handling application, the wooden pallet supply chain. The main decisions affecting circularity and the most common decision alternatives for the wooden pallet supply chain are identified for the Pre-manufacturing, manufacturing, product delivery, customer use, and end-of-life phases. A streamlined life cycle assessment tool is developed for supporting a quick analysis about how the level of adoption of CE strategies could support environmental sustainability in pallet supply chains. A questionnaire, scoring, and assessment are presented for each phase of a pallet supply chain to reduce input and use of natural resources, reduce emission levels, reduce valuable materials losses, increase share of renewable and recyclable resources, and increase the value of durability of products. A case study is used to test the proposed method and present a contrast between two scenarios