Engineering Commons^™

Deployable Lenticular Stiffeners For Origami-Inspired Mechanisms, Larry L. Howell, Alden D. Yellowstone

Faculty Publications

Light-weight origami-inspired mechanisms can provide advantages in deployable space systems and other applications. However, a significant challenge in their design is ensuring that they are sufficiently stiff. Compliant, deployable stiffeners utilizing a profile approximating the Euler Spiral are proposed as one solution. Structures with this profile, called a lenticular stiffener, are shown to permit stiffeners to flatten using forces applied at their edges. Formulas for calculating the stiffness increase are developed. Relations needed to design the deployment behavior of the stiffeners are also derived. Finally, advantages of different stiffener configurations are evaluated. These results are verified through simulation and experiments.

Kinematic/Static Model Of Complex Compliant Mechanisms With Serial-Parallel Substructures: A General Approach, Larry L. Howell, Mingxiang Ling, Junyi Cao

Faculty Publications

Kinematic and static analyses of compliant mechanisms are crucial at the early stage of design, and it can be difficult and laborsome for complex configurations with distributed compliance. In this paper, a general and concise kinematic/static modeling method of flexure-hinge-based compliant mechanisms with arbitrary serial-parallel substructures is presented to provide accurate and efficient solutions by combining the matrix displacement method with the transfer matrix method. The transition between the elemental stiffness matrix and the transfer matrix of the flexure hinge and the flexible beam is straightforward, enabling the condensation of a hybrid serial-parallel substructure into one equivalent element simple. Then, …

Distributed Electric Propulsion Effects On Traditional Aircraft Through Multidisciplinary Optimization, Kevin Moore, Andrew Ning

Faculty Publications

Electric aircraft face a steep tradeoff between the demand for runway performance and range. While fuel based propulsion technologies typically increase in specific power with increasing size, electric propulsion is typically much more scalable. This system scalability enables alternative designs including distributed propulsion, optionally powered propulsion units, and vectored thrust, which can all contribute to better runway performance and range. In this paper, we explore how continuously powered distributed propulsion can reduce takeoff distance while still satisfying range constraints. We use a combination of a blade element momentum method, a vortex lattice method, experimental data, and nonlinear optimization techniques to …

Benefits Of Two Turbine Rotor Diameters And Hub Heights In The Same Wind Farm, Andrew Pj Stanley, Andrew Ning, Katherine Dykes

Faculty Publications

Significant turbine-wake interactions greatly reduce power output in a wind farm. If different turbine hub heights and rotor diameters are included in the same wind farm, the wake interference in the farm will be reduced, resulting in a lower cost of energy (COE) than a farm with identical turbines. In this paper, we present a method to model wind farm COE in farms with hub heights and rotor diameters that vary across the wind farm. We also demonstrate how to optimize these wind farms to minimize COE. The results show that COE can be greatly reduced in wind farms with …

A Comparison Of Traditional And Adaptive Comparative Judgment Assessment Techniques For Freshmen Engineering Design Projects, Scott R. Bartholomew, Greg J. Strimel, Andrew Jackson

Faculty Publications

This article examines the use of an alternative form of assessment for engineering design projects called adaptive comparative judgment (ACJ). The researchers employed an ACJ tool to evaluate undergraduate engineering student design projects in an effort to examine its’ reliability, validity, and utility in comparison with traditional assessment techniques. The ACJ process employed multiple judges to compare the design artifacts of 16 first-year engineering majors. The authors conducted an analysis of the reliability and validity of the ACJ method compared to the traditional rubric used to evaluate the project and the performance data of each student’s design prototype. For these …

Characterization Of Pyrolysis Products From Fast Pyrolysis Of Live And Dead Vegetation Native To The Southern United States, Mohammad-Saeed Safdari, Mahmood Rahmati, Elham Amini, Joel E. Howarth, Jansen P. Berryhill, Mark Dietenberger, David R. Weise, Thomas H. Fletcher

Faculty Publications

Prescribed burning (controlled burning) is used to decrease accumulation of combustible materials and reduce impact of uncontrolled wildland fires. Prescribed fires are often used to burn undergrowth in Southern forests of the United States. In order to improve prescribed fire application, accomplish desired fire effects, and limit potential runaway fires, an improved understanding of the fundamental processes related to combustion of heterogeneous fuel beds of live and dead fuels is needed. The initial processes of combustion involve pyrolysis and ignition. During this research, fast pyrolysis of 14 live and dead (biomass) plant species which are native to the Southern United …

Effect Of Different Alumina Supports On Performance Of Cobalt Fischer-Tropsch Catalysts, Thomas H. Fletcher

Faculty Publications

Four identically-prepared 20 wt% cobalt/0.15 wt% ruthenium Fischer-Tropsch catalysts, supported on different aluminas, were synthesized by incipient wetness impregnation, characterized, and compared based on their performance under standard Fischer-Tropsch synthesis conditions. Three alumina supports were obtained from commercial sources (Sasol, St. Gobain, and Alfa Aesar), while the fourth was made using a published technique that included 5 wt% silica. The silica-stabilized alumina catalyst produced superior Fischer-Tropsch rates of 49 mmol CO/gcat h, compared to the other catalysts on the commercial supports with rates of 26–39 mmol CO/gcat h. The improved performance of the silica-stabilized alumina support compared to the commercially …

Development Of Bioreactors For Comparative Study Of Naturalattenuation, Biostimulation, And Bioaugmentation Ofpetroleum-Hydrocarbon Contaminated Soil, Mohammad-Saeed Safdari, Hamid-Reza Kariminia, Mahmood Rahmati, Farhad Fazlollahi, Alexandra Polasko, Shaily Mahendra, W Vincent Wilding, Thomas H. Fletcher

Faculty Publications

Bioremediation of soil and groundwater sites contaminated by petroleum hydrocarbons is known as a technically viable, cost-effective, and environmentally sustainable technology. The purpose of this study is to investigate laboratory-scale bioremediation of petroleum-hydrocarbon contaminated soil through development of eight bioreactors, two bioreactors for each bioremediation mode. The modes were: (1)natural attenuation (NA); (2) biostimulation (BS) with oxygen and nutrients; (3) bioaugmentation (BA)with hydrocarbon degrading isolates; (4) a combination of biostimulation and bioaugmentation (BS-BA). Total petroleum hydrocarbons (TPH) mass balance over the bioreactors showed about 2% of initial20,000 mg kg-soil−1TPH was removed by advection due to synthetic groundwater which was flow-ing …

Adaptive Differential Thrust Methodology For Lateral/Directional Stability Of An Aircraft With A Completely Damaged Vertical Stabilizer, Long K. Lu, Kamran Turkoglu

Faculty Publications

This paper investigates the utilization of differential thrust to help a commercial aircraft with a damaged vertical stabilizer in order to regain its lateral/directional stability. In the event of an aircraft losing its vertical stabilizer, the consequential loss of the lateral/directional stability and control is likely to cause a fatal crash. In this paper, an aircraft with a completely damaged vertical stabilizer is investigated, and a unique differential thrust-based adaptive control approach is proposed to achieve a stable flight envelope. The propulsion dynamics of the aircraft is modeled as a system of differential equations with engine time constant and time …

Patient Friendly Kidney Function Screening, Ragwa El Sayed, Rathna Ramesh, Alessandro Bellofiore, David Anastasiu, Melinda Simon

Faculty Publications

No abstract provided.

Teaching With Jupyter In-Class Activities: Lessons Learned And Next Steps, David Anastasiu

Faculty Publications

No abstract provided.

Multidisciplinary Design Optimization Of Flexible Solar-Regenerative High-Altitude Long-Endurance Aircraft, Taylor Mcdonnell, Judd Mehr, Andrew Ning

Faculty Publications

Solar-Regenerative High-Altitude Long-Endurance (SR-HALE) aircraft are designed to sustain year-round flight at high altitudes indefinitely. No SR-HALE aircraft has yet accomplished this task due to the complex network of environmental, solar, structural, and aerodynamic trade-offs, among which aircraft flexibility plays a key role. A comprehensive SR-HALE aircraft multidisciplinary design optimization framework is developed in which the flexible aircraft analysis tool ASWING is incorporated in order to constrain nonlinear aeroelasticity. Energy, battery, ply thickness, material failure, local buckling, aerodynamic stall, longitudinal stability, and general stability (including flutter) constraints are applied in order to reasonably constrain the optimized SR-HALE aircraft design. An …

Large-Scale Multidisciplinary Optimization Of An Electric Aircraft For On-Demand Mobility, John Hwang, Andrew Ning

Faculty Publications

Distributed electric propulsion is a key enabling technology for on-demand electric aircraft concepts. NASA’s X-57 Maxwell X-plane is a demonstrator for this technology, and it features a row of high-lift propellers distributed along the leading edge of its wing to enable better aerodynamic efficiency at cruise and improved ride quality in addition to less noise and emissions. This study applies adjoint- based multidisciplinary design optimization to this highly coupled design problem. The propulsion, aerodynamics, and structures are modeled using blade element momentum theory, the vortex lat- tice method, and finite element analysis, respectively, and the full mission profile is discretized …

Impact Of Vapor Polishing On Surface Quality And Mechanical Properties Of Extruded Abs, Clayton Neff, Matthew Trapuzzano, Nathan B. Crane

Faculty Publications

Purpose — Additive manufacturing (AM) is readily capable of producing models and prototypes of complex geometry and is advancing in creating functional parts. However, AM processes typically underperform traditional manufacturing methods in mechanical properties, surface roughness, and hermeticity. Solvent vapor treatments (vapor polishing) are commonly used to improve surface quality in thermoplastic parts, but the results are poorly characterized.

Design/methodology/approach — This work quantifies the surface roughness change and also evaluates the effect on hermeticity and mechanical property impacts for “as-printed” and acetone vapor-polished ABS tensile specimens of 1, 2, and 4 mm thicknesses produced by material extrusion (FDM).

Findings …

Controlling Normal Stiffness In Droplet-Based Linear Bearings, Qi Ni, Nathan B. Crane

Faculty Publications

While Capillary forces are negligible relative to gravity at the macroscale, they provide adequate force to effectively manipulate millimeter to micro meter objects. The fluidic actuation can be accomplished using droplets that also act as bearings. While rotary droplet bearings have been previously demonstrated, this paper considers the performance potential of discrete droplets acting as linear bearings. Specifically, it addresses the positioning accuracy of a droplet-based bearing consisting of a droplet between a moving plate and a stationary substrate with constrained wetting region under a normal load using both closed form analytical solutions and numerical simulations. The vertical force and …

Examining Engineering Design Cognition With Respect To Student Experience And Performance, Greg J. Strimel, Eunhye Kim, Scott R. Bartholomew, Diana V. Cantu

Faculty Publications

This study investigated the design cognition and performance results of secondary and post-secondary engineering students while engaged in an engineering design task. Relationships between prototype performance and design cognition were highlighted to investigate potential links between cognitive processes and success on engineering design problems. Concurrent think-aloud protocols were collected from eight secondary and 12 post-secondary engineering students working individually to design, make, and evaluate a solution prototype to an engineering design task. The collected protocols were segmented and coded using a pre-established coding scheme. The results were then analyzed to compare the two participant groups and determine the relationships between …

Adaptive Comparative Judgment For Polytechnic Transformation: Assessment Across The Curriculum, Scott R. Bartholomew, P. E. Connolly

Faculty Publications

The authors are investigating potential applications of adaptive comparative judgment (ACJ) across numerous environments and learning scenarios within the Purdue Polytechnic Institute as part of Purdue’s efforts to transform the undergraduate learning experience. Six courses or program areas were selected for the study, involving a wide variation in subjects, subject matter, and assessment artifacts. The authors anticipate that positive results from these pilot studies will encourage broader and deeper applications of ACJ in the Purdue Polytechnic, across Purdue University, and in other academic institutions. Results from these scenarios will be disseminated in future conferences and scholarly journals.

Effects Of Ag Promotion And Preparation Method On Cobalt Fischer- Tropsch Catalysts Supported On Silica-Modified Alumina, Mahmood Rahmati, Baiyu Huang, Landon M. Schofield, Thomas H. Fletcher, Brian F. Woodfield, William C. Hecker, Calvin H. Bartholomew, Morris D. Argyle

Faculty Publications

A series of silver-promoted, 20 wt% cobalt Fischer-Tropsch synthesis (FTS) catalysts supported on an alumina modified with 5 wt% silica were prepared using two methods: traditional incipient wetness impregnation (IWI) and a new solvent deficient precipitation (SDP) technique. Catalysts containing silver promoter concentrations of 0.3, 0.6, 1.2, and 2.5 wt% were prepared using each of the two methods. Silver improved the reducibility of the cobalt significantly, lowering reduction temperatures by up to 100 C, and increasing the extent of reduction by up to 35%. Further, in both preparation methods, changing the silver loading altered the cobalt dispersion. The smallest Co …

Formation Of Deposits From Heavy Fuel Oil Ash In An Accelerated Deposition Facility At Temperatures Up To 1219 °C, Robert Laycock, Thomas H. Fletcher

Faculty Publications

Some industrial gas turbines are currently being fired using heavy fuel oil, which contains a small percentage of inorganic material that can lead to fouling and corrosion of turbine components. Deposits of heavy fuel oil ash were created in the Turbine Accelerated Deposition Facility (TADF) at Brigham Young University under gas turbine-related conditions. Ash was produced by burning heavy fuel oil in a downward-fired combustor and collecting the ash from the exhaust stream. This ash was then introduced into the TADF and entrained in a hot gas flow that varied from 1101 °C to 1219 °C. Sulfur dioxide was introduced …

Fire Behavior In Chaparral–Evaluating Flame Models With Laboratory Data, David R. Weise, Thomas H. Fletcher, Wesley Cole, Shankar Mahalingam, Xiangyang Zhou, Lulu Sun, Jing Li

Faculty Publications

Flame and mass loss data for chaparral, a mixture of shrub plants from the Mediterranean climate zone of southwestern North America, from five previously reported experiments were used to evaluate several published models relating flame characteristics to mass loss and heat release rates. These data are unique with fuel moisture content ranging from 0.36 to 0.94 (dry basis); the study used mass loss rates which included water loss. Fit of the data to Froude number correlations developed by Albini, Byram, Nelson and Thomas and heat release rate—flame length correlations by Heskestad, Zukoski, and Yuan/Cox for axisymmetric and line fires were …

Lab-Scale Observations Of Flame Attachment On Slopes With Implications For Firefighter Safety Zones, Jonathan R. Gallacher, Brad Ripa, Bret W. Butler, Thomas H. Fletcher

Faculty Publications

The Coanda effect is the phenomenon in which a jet entering quiescent fluid attaches to a nearby solid object due to inhibited entrainment of ambient fluid near the solid. Little is known about the influence of the Coanda effect on wildland fire behavior. Specifically, there is a lack of knowledge regarding how the flame attachment on slopes influences firefighter safety zone considerations in rugged terrain. This paper presents results for small-scale n-heptane pool fire experiments near a slope, showing how flame shape and heat flux are influenced by slope angle, slope boundary condition and distance from flame base. Flames near …

Wavelet Anova Bisection Method For Identifying Simulation Model Bias, Andrew D. Atkinson, Raymond R. Hill, Joseph J. Pignatiello Jr., G. Geoffrey Vining, Edward D. White, Eric Chicken

Faculty Publications

High-resolution computer models can simulate complex systems and processes in order to evaluate a solution quickly and inexpensively. Many simulation models produce dynamic functional output, such as a set of time-series data generated during a process. These computer models require verification and validation (V&V) to assess the correctness of these simulations. In particular, the model validation effort evaluates if the model is an appropriate representation of the real-world system that it is meant to simulate. However, when assessing a model capable of generating functional output, it is useful to learn more than simply whether the model is valid or invalid. …

Unmasking Cost Growth Behavior: A Longitudinal Study, Cory N. D'Amico, Edward D. White, Jonathan D. Ritschel, Scott R. Kozlak

Faculty Publications

This article examines how cost growth factors (CGF) change over a program’s acquisition life cycle for 36 Department of Defense aircraft programs. Starting from Milestone B, the authors examine CGFs at five gateways: Critical Design Review, First Flight (FF), the end of Developmental Test and Evaluation (DT&E), Initial Operational Capability, and Full Operational Capability. Each CGF is assigned a color rating based upon the program’s cost growth: Green (low), Amber (moderate), or Red (high). Significant findings include dependencies among similar CGF color ratings and cost growth occurring primarily between FF and the end of DT&E during a program’s life cycle.

Evaluating Smartphones For Infrastructure Work Order Management, Victor L. Guinn, Brent T. Langhals, John J. Elshaw

Faculty Publications

Infrastructure managers require timely and accurate state information to diagnose, prioritize, and repair the substantial infrastructure assets supporting modern society. Challenges in obtaining sufficient information can often be attributed to inadequate data collection procedures (phone calls, paper reports, etc.) or a general lack of knowledge or ability on the part of the reporting individual to accurately convey what is actually wrong with the facility. Fortunately, modern smart-phone technology offers the potential to improve maintenance work requests by providing better geolocation and problem description accuracy. An experiment simulating real-world maintenance requests was conducted comparing smart-phones with traditional verbal work order request …

Material State Awareness For Composites Part Ii: Precursor Damage Analysis And Quantification Of Degraded Material Properties Using Quantitative Ultrasonic Image Correlation (Quic), Subir Patra, Sourav Banerjee

Faculty Publications

Material state awareness of composites using conventional Nondestructive Evaluation (NDE) method is limited by finding the size and the locations of the cracks and the delamination in a composite structure. To aid the progressive failure models using the slow growth criteria, the awareness of the precursor damage state and quantification of the degraded material properties is necessary, which is challenging using the current NDE methods. To quantify the material state, a new offline NDE method is reported herein. The new method named Quantitative Ultrasonic Image Correlation (QUIC) is devised, where the concept of microcontinuum mechanics is hybrid with the experimentally …

Material State Awareness For Composites Part I: Precursor Damage Analysis Using Ultrasonic Guided Coda Wave Interferometry (Cwi), Subir Patra, Sourav Banerjee

Faculty Publications

Detection of precursor damage followed by the quantification of the degraded material properties could lead to more accurate progressive failure models for composite materials. However, such information is not readily available. In composite materials, the precursor damages—for example matrix cracking, microcracks, voids, interlaminar pre-delamination crack joining matrix cracks, fiber micro-buckling, local fiber breakage, local debonding, etc.—are insensitive to the low-frequency ultrasonic guided-wave-based online nondestructive evaluation (NDE) or Structural Health Monitoring (SHM) (~100–~500 kHz) systems. Overcoming this barrier, in this article, an online ultrasonic technique is proposed using the coda part of the guided wave signal, which is often neglected. Although …

Sexual Recombination And Increased Mutation Rate Expedite Evolution Of Escherichia Coli In Varied Fitness Landscapes, George Peabody, Hao Li, Katy Kao

Faculty Publications

Sexual recombination and mutation rate are theorized to play different roles in adaptive evolution depending on the fitness landscape; however, direct experimental support is limited. Here we examine how these factors affect the rate of adaptation utilizing a “genderless” strain of Escherichia coli capable of continuous in situ sexual recombination. The results show that the populations with increased mutation rate, and capable of sexual recombination, outperform all the other populations. We further characterize two sexual and two asexual populations with increased mutation rate and observe maintenance of beneficial mutations in the sexual populations through mutational sweeps. Furthermore, we experimentally identify …

Combined Noncyclic Scheduling And Advanced Control For Continuous Chemical Processes, Damon Petersen, Logan D. R. Beal, Derek Prestwich, Sean Warnick, John Hedengren

Faculty Publications

A novel formulation for combined scheduling and control of multi-product, continuous chemical processes is introduced in which nonlinear model predictive control (NMPC) and noncyclic continuous-time scheduling are efficiently combined. A decomposition into nonlinear programming (NLP) dynamic optimization problems and mixed-integer linear programming (MILP) problems, without iterative alternation, allows for computationally light solution. An iterative method is introduced to determine the number of production slots for a noncyclic schedule during a prediction horizon. A filter method is introduced to reduce the number of MILP problems required. The formulation’s closed-loop performance with both process disturbances and updated market conditions is demonstrated through …

Parallel Cosine Nearest Neighbor Graph Construction, David Anastasiu, George Karypis

Faculty Publications

The nearest neighbor graph is an important structure in many data mining methods for clustering, advertising, recommender systems, and outlier detection. Constructing the graph requires computing up to n2 similarities for a set of n objects. This high complexity has led researchers to seek approximate methods, which find many but not all of the nearest neighbors. In contrast, we leverage shared memory parallelism and recent advances in similarity joins to solve the problem exactly. Our method considers all pairs of potential neighbors but quickly filters pairs that could not be a part of the nearest neighbor graph, based on similarity …

Development And Field Testing Of An Interactive Transit Station Information System (Itsis) Using Connected Vehicle Technologies, Huadong Meng, Jacob Tsao, Kun Zhou, Justin Picar, Bradley Mizuno, Wei-Bin Zhang

Faculty Publications

The objective of Interactive Transit Station Information System (ITSIS) is to better inform transit travelers during their trips and to enable dynamic transit operations to better serve travelers. The ultimate goal is to make transit more friendly and attractive to the traveling population such that transit will become a viable choice for travel and an integrated part of the solution for congestion relief. This report documents a research effort to develop and test a ITSIS prototype that uses Connected Vehicle technologies to enable the real-time interaction between passengers and transit systems at bus stations. The reports summarizes the findings from …