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151,993 full-text articles. Page 6 of 4460.

Incorporation Of Composite Defects From Ultrasonic Nde Into Cad And Fe Models, Onur Rauf Bingol, Bryan Schiefelbein, Robert J. Grandin, Stephen D. Holland, Adarsh Krishnamurthy 2019 Iowa State University

Incorporation Of Composite Defects From Ultrasonic Nde Into Cad And Fe Models, Onur Rauf Bingol, Bryan Schiefelbein, Robert J. Grandin, Stephen D. Holland, Adarsh Krishnamurthy

Stephen D. Holland

Fiber-reinforced composites are widely used in aerospace industry due to their combined properties of high strength and low weight. However, owing to their complex structure, it is difficult to assess the impact of manufacturing defects and service damage on their residual life. While, ultrasonic testing (UT) is the preferred NDE method to identify the presence of defects in composites, there are no reasonable ways to model the damage and evaluate the structural integrity of composites. We have developed an automated framework to incorporate flaws and known composite damage automatically into a finite element analysis (FEA) model of composites, ultimately aiding ...


Model-Assisted Probability Of Detection Of Flaws In Aluminum Blocks Using Polynomial Chaos Expansions, Xiaosong Du, Leifur Leifsson, Robert J. Grandin, William Q. Meeker, Ronald A. Roberts, Jiming Song 2019 Iowa State University

Model-Assisted Probability Of Detection Of Flaws In Aluminum Blocks Using Polynomial Chaos Expansions, Xiaosong Du, Leifur Leifsson, Robert J. Grandin, William Q. Meeker, Ronald A. Roberts, Jiming Song

William Q Meeker

Probability of detection (POD) is widely used for measuring reliability of nondestructive testing (NDT) systems. Typically, POD is determined experimentally, while it can be enhanced by utilizing physics-based computational models in combination withmodel-assisted POD (MAPOD) methods. With the development of advanced physics-basedmethods, such as ultrasonic NDTtesting, the empirical information,needed for POD methods, can bereduced. However, performing accurate numerical simulationscan be prohibitivelytime-consuming, especially as part of stochastic analysis. In this work, stochastic surrogate models for computational physics-based measurement simulations are developed for cost savings of MAPOD methods while simultaneously ensuring sufficient accuracy. The stochastic surrogate is used to propagate the ...


Model-Assisted Probability Of Detection Of Flaws In Aluminum Blocks Using Polynomial Chaos Expansions, Xiaosong Du, Leifur Leifsson, Robert J. Grandin, William Q. Meeker, Ronald A. Roberts, Jiming Song 2019 Iowa State University

Model-Assisted Probability Of Detection Of Flaws In Aluminum Blocks Using Polynomial Chaos Expansions, Xiaosong Du, Leifur Leifsson, Robert J. Grandin, William Q. Meeker, Ronald A. Roberts, Jiming Song

Jiming Song

Probability of detection (POD) is widely used for measuring reliability of nondestructive testing (NDT) systems. Typically, POD is determined experimentally, while it can be enhanced by utilizing physics-based computational models in combination withmodel-assisted POD (MAPOD) methods. With the development of advanced physics-basedmethods, such as ultrasonic NDTtesting, the empirical information,needed for POD methods, can bereduced. However, performing accurate numerical simulationscan be prohibitivelytime-consuming, especially as part of stochastic analysis. In this work, stochastic surrogate models for computational physics-based measurement simulations are developed for cost savings of MAPOD methods while simultaneously ensuring sufficient accuracy. The stochastic surrogate is used to propagate the ...


Surrogate Modeling Of Ultrasonic Simulations Using Data-Driven Methods, Xiaosong Du, Robert J. Grandin, Leifur Leifsson 2019 Iowa State University

Surrogate Modeling Of Ultrasonic Simulations Using Data-Driven Methods, Xiaosong Du, Robert J. Grandin, Leifur Leifsson

Robert Grandin

Ultrasonic testing (UT) is used to detect internal flaws in materials and to characterize material properties. In many applications, computational simulations are an important part of the inspection-design and analysis processes. Having fast surrogate models for UT simulations is key for enabling efficient inverse analysis and model-assisted probability of detection (MAPOD). In many cases, it is impractical to perform the aforementioned tasks in a timely manner using current simulation models directly. Fast surrogate models can make these processes computationally tractable. This paper presents investigations of using surrogate modeling techniques to create fast approximate models of UT simulator responses. In particular ...


Model-Assisted Probability Of Detection Of Flaws In Aluminum Blocks Using Polynomial Chaos Expansions, Xiaosong Du, Leifur Leifsson, Robert J. Grandin, William Q. Meeker, Ronald A. Roberts, Jiming Song 2019 Iowa State University

Model-Assisted Probability Of Detection Of Flaws In Aluminum Blocks Using Polynomial Chaos Expansions, Xiaosong Du, Leifur Leifsson, Robert J. Grandin, William Q. Meeker, Ronald A. Roberts, Jiming Song

Robert Grandin

Probability of detection (POD) is widely used for measuring reliability of nondestructive testing (NDT) systems. Typically, POD is determined experimentally, while it can be enhanced by utilizing physics-based computational models in combination withmodel-assisted POD (MAPOD) methods. With the development of advanced physics-basedmethods, such as ultrasonic NDTtesting, the empirical information,needed for POD methods, can bereduced. However, performing accurate numerical simulationscan be prohibitivelytime-consuming, especially as part of stochastic analysis. In this work, stochastic surrogate models for computational physics-based measurement simulations are developed for cost savings of MAPOD methods while simultaneously ensuring sufficient accuracy. The stochastic surrogate is used to propagate the ...


Utsim2 Validation, Robert J. Grandin, Tim Gray 2019 Iowa State University

Utsim2 Validation, Robert J. Grandin, Tim Gray

Robert Grandin

The Center for NDE (CNDE) at Iowa State University has a long history of developing physics models for NDE and packaging these models into simulation tools which make the modeling capabilities accessible to CNDEs industrial sponsors. Recent work at CNDE has led to the development of a new ultrasonic simulation package, UTSim2, which aims to continue this tradition of supporting industrial application of CNDE models. In order to meet this goal, UTSim2 has been designed as an extensible software package which can support previously-developed physics models as well as future models yet to be developed. Initial work has focused on ...


Incorporation Of Composite Defects From Ultrasonic Nde Into Cad And Fe Models, Onur Rauf Bingol, Bryan Schiefelbein, Robert J. Grandin, Stephen D. Holland, Adarsh Krishnamurthy 2019 Iowa State University

Incorporation Of Composite Defects From Ultrasonic Nde Into Cad And Fe Models, Onur Rauf Bingol, Bryan Schiefelbein, Robert J. Grandin, Stephen D. Holland, Adarsh Krishnamurthy

Robert Grandin

Fiber-reinforced composites are widely used in aerospace industry due to their combined properties of high strength and low weight. However, owing to their complex structure, it is difficult to assess the impact of manufacturing defects and service damage on their residual life. While, ultrasonic testing (UT) is the preferred NDE method to identify the presence of defects in composites, there are no reasonable ways to model the damage and evaluate the structural integrity of composites. We have developed an automated framework to incorporate flaws and known composite damage automatically into a finite element analysis (FEA) model of composites, ultimately aiding ...


A Comprehensive Study Of Sequential Simulated Moving Bed: Purification Of Xylo-Oligosaccharides And Fructose-Glucose, Yan Li 2019 The University of Western Ontario

A Comprehensive Study Of Sequential Simulated Moving Bed: Purification Of Xylo-Oligosaccharides And Fructose-Glucose, Yan Li

Electronic Thesis and Dissertation Repository

Chromatographic separation is a promising alternative for separation and purification of sugars in industry. Simulated moving bed (SMB) technique has been proven as an efficient chromatographic separation method due to its enhanced productivity and purity, reduced solvent consumption, convenient operating control, and improved separation performance for some systems with low resolution and selectivity. The sequential simulated moving bed (SSMB) is a modification of the conventional SMB process, which currently has some applications for sugar separation due to its low solvent consumption. This work mainly investigates the design strategy of the innovative SSMB process and explore its advantages and disadvantages over ...


Exercises Integrating High School Mathematics With Robot Motion Planning, Ronald I. Greenberg, George K. Thiruvathukal 2019 Loyola University Chicago

Exercises Integrating High School Mathematics With Robot Motion Planning, Ronald I. Greenberg, George K. Thiruvathukal

Computer Science: Faculty Publications and Other Works

This paper presents progress in developing exercises for high school students incorporating level-appropriate mathematics into robotics activities. We assume mathematical foundations ranging from algebra to precalculus, whereas most prior work on integrating mathematics into robotics uses only very elementary mathematical reasoning or, at the other extreme, is comprised of technical papers or books using calculus and other advanced mathematics. The exercises suggested are relevant to any differerential-drive robot, which is an appropriate model for many different varieties of educational robots. They guide students towards comparing a variety of natural navigational strategies making use of typical movement primitives. The exercises align ...


Dear Neil Armstrong: Letters To The First Man From All Mankind, James R. Hansen 2019 Purdue University

Dear Neil Armstrong: Letters To The First Man From All Mankind, James R. Hansen

Purdue University Press Book Previews

In the years between the historic first moon landing by Apollo 11 on July 20, 1969, and his death at age 82 on August 25, 2012, Neil Armstrong received hundreds of thousands of cards and letters from all over the world, congratulating him, praising him, requesting pictures and autographs, and asking him what must have seemed to him to be limitless—and occasionally intrusive—questions. Of course, all the famous astronauts received fan mail, but the sheer volume Armstrong had to deal with for more than four decades after his moon landing was staggering.

Today, the preponderance of those letters ...


Tensorial Stress−Strain Fields And Large Elastoplasticity As Well As Friction In Diamond Anvil Cell Up To 400 Gpa, Valery I. Levitas, Mehdi Kamrani, Biao Feng 2019 Iowa State University and Ames Labortory

Tensorial Stress−Strain Fields And Large Elastoplasticity As Well As Friction In Diamond Anvil Cell Up To 400 Gpa, Valery I. Levitas, Mehdi Kamrani, Biao Feng

Aerospace Engineering Publications

Various phenomena (fracture, phase transformations, and chemical reactions) studied under extreme pressures in diamond anvil cell are strongly affected by fields of all components of stress and plastic strain tensors. However, they could not be measured. Here, we suggest a coupled experimental−theoretical−computational approach that allowed us (using published experimental data) to refine, calibrate, and verify models for elastoplastic behavior and contact friction for tungsten (W) and diamond up to 400 GPa and reconstruct fields of all components of stress and large plastic strain tensors in W and diamond. Despite the generally accepted strain-induced anisotropy, strain hardening, and path-dependent ...


Textual Comparison Of Role Model And Mentor Profiles Developed To Increase Participation Of Underrepresented Minorities In Stem, Kyle F. Trenshaw, Elif Miskioglu, Philip Asare, Nir Aish 2019 University of Rochester

Textual Comparison Of Role Model And Mentor Profiles Developed To Increase Participation Of Underrepresented Minorities In Stem, Kyle F. Trenshaw, Elif Miskioglu, Philip Asare, Nir Aish

Faculty Conference Papers and Presentations

No abstract provided.


Interpretable Deep Learning For Guided Microstructure-Property Explorations In Photovoltaics, Balaji Sesha Sarath Pokuri, Sambuddha Ghosal, Apurva Kokate, Soumik Sarkar, Baskar Ganapathysubramanian 2019 Iowa State University

Interpretable Deep Learning For Guided Microstructure-Property Explorations In Photovoltaics, Balaji Sesha Sarath Pokuri, Sambuddha Ghosal, Apurva Kokate, Soumik Sarkar, Baskar Ganapathysubramanian

Mechanical Engineering Publications

The microstructure determines the photovoltaic performance of a thin film organic semiconductor film. The relationship between microstructure and performance is usually highly non-linear and expensive to evaluate, thus making microstructure optimization challenging. Here, we show a data-driven approach for mapping the microstructure to photovoltaic performance using deep convolutional neural networks. We characterize this approach in terms of two critical metrics, its generalizability (has it learnt a reasonable map?), and its intepretability (can it produce meaningful microstructure characteristics that influence its prediction?). A surrogate model that exhibits these two features of generalizability and intepretability is particularly useful for subsequent design exploration ...


Factors Influencing Cellulosic Sugar Production During Acid-Catalyzed Solvent Liquefaction In 1,4-Dioxane, Arpa Ghosh, Robert C. Brown 2019 Iowa State University

Factors Influencing Cellulosic Sugar Production During Acid-Catalyzed Solvent Liquefaction In 1,4-Dioxane, Arpa Ghosh, Robert C. Brown

Mechanical Engineering Publications

This work explores the use of 1,4-dioxane to depolymerize cellulose into solubilized carbohydrates. This low boiling point solvent offers inexpensive and simple separation compared to higher boiling point solvents such as γ-valerolactone previously considered for acid-catalyzed depolymerization of cellulose. In the present study, several key reaction parameters, including reaction temperature, catalyst concentration, and water content, were studied as major factors influencing sugar production from cellulose. A maximum yield of 51% for levoglucosan, the major product of cellulose depolymerization, was achieved at higher temperature, shorter reaction time and lower acid concentration in the ranges tested for these parameters. Addition of ...


Nutrition At The Crossroads: Food At The Intersection Of Environmental, Economic, And Social Sustainability, Kurt A. Rosentrater, Laetitia Palmade, Elif Kongar 2019 Iowa State University

Nutrition At The Crossroads: Food At The Intersection Of Environmental, Economic, And Social Sustainability, Kurt A. Rosentrater, Laetitia Palmade, Elif Kongar

Agricultural and Biosystems Engineering Publications

Societies around the world are at a critical juncture. As the planetary population grows, there are increasing demands for expanding available food, more nutritious and healthy foods, and contemporaneously the need for greater efficiencies and decreased impacts upon the environment.

The sustainability of food production systems is a complex issue that requires a global and multidisciplinary approach, combining not only agronomy, ecology, nutrition, epidemiology, processing, energy use, but also marketing and sociology. It is within this context that this special issue aims to illustrate, through review articles, case studies, as well as modeling and simulation studies, some means of understanding ...


Design And Validation Of A Mobile Air Filter Testing Laboratory For Animal Agricultural Applications, Benjamin C. Smith, Brett C. Ramirez, Steven J. Hoff, Jay D. Harmon, John P. Stinn 2019 Iowa State University

Design And Validation Of A Mobile Air Filter Testing Laboratory For Animal Agricultural Applications, Benjamin C. Smith, Brett C. Ramirez, Steven J. Hoff, Jay D. Harmon, John P. Stinn

Agricultural and Biosystems Engineering Publications

The US swine industry is shifting towards filtered fresh-air ventilation systems that use pleated filters to improve breeding herd health and reduce airborne disease outbreak frequency. Loaded filters reduce airflow causing a poor environment and elevated energy use. Typical axial fans cannot efficiently maintain the rated differential pressure (DP; 100 Pa) for pleated filters; hence, a lower design filter DP (37 Pa) is used and consequently, more filters are required to achieve design maximum ventilation. Large, common filter banks for multiple staged fans presents significant challenges in using continuous DP measurement to assess filter life, making it impossible to separate ...


Engineering News, Fall 2019, School of Engineering 2019 Santa Clara University

Engineering News, Fall 2019, School Of Engineering

Engineering News

No abstract provided.


Ultrasound Scatter In Heterogeneous 3d Microstructures: Parameters Affecting Multiple Scattering, Brady J. Engle, Ronald A. Roberts, Robert J. Grandin 2019 Iowa State University

Ultrasound Scatter In Heterogeneous 3d Microstructures: Parameters Affecting Multiple Scattering, Brady J. Engle, Ronald A. Roberts, Robert J. Grandin

Robert Grandin

This paper reports on a computational study of ultrasound propagation in heterogeneous metal microstructures. Random spatial fluctuations in elastic properties over a range of length scales relative to ultrasound wavelength can give rise to scatter-induced attenuation, backscatter noise, and phase front aberration. It is of interest to quantify the dependence of these phenomena on the microstructure parameters, for the purpose of quantifying deleterious consequences on flaw detectability, and for the purpose of material characterization. Valuable tools for estimation of microstructure parameters (e.g. grain size) through analysis of ultrasound backscatter have been developed based on approximate weak-scattering models. While useful ...


Evaluation Of The Fidelity Of Feature Descriptor-Based Specimen Tracking For Automatic Nde Data Integration, Rafael Radkowski, Stephen D. Holland, Robert J. Grandin 2019 Iowa State University

Evaluation Of The Fidelity Of Feature Descriptor-Based Specimen Tracking For Automatic Nde Data Integration, Rafael Radkowski, Stephen D. Holland, Robert J. Grandin

Robert Grandin

This research addresses inspection location tracking in the field of nondestructive evaluation (NDE) using a computer vision technique to determine the position and orientation of typical NDE equipment in a test setup. The objective is the tracking accuracy for typical NDE equipment to facilitate automatic NDE data integration. Since the employed tracking technique relies on surface curvatures of an object of interest, the accuracy can be only experimentally determined. We work with flash-thermography and conducted an experiment in which we tracked a specimen and a thermography flash hood, measured the spatial relation between both, and used the relation as input ...


Utilizing An Individually Built Mobile Robot In The Laboratory Of An Advanced Digital Logic Design Course In Conjunction With A Final Class Competition, Clinton E. Kohl 2019 Cedarville University

Utilizing An Individually Built Mobile Robot In The Laboratory Of An Advanced Digital Logic Design Course In Conjunction With A Final Class Competition, Clinton E. Kohl

Clinton Kohl, Ph.D.

This paper describes the development and implementation of a series of laboratory projects utilized in a junior level, required course for computer engineering majors titled, “Advanced Digital Logic Design.” Eleven of the 13 lab experiences are directly related to this project.

The first five labs are mainly construction labs where students are developing practical hands-on skills and gaining familiarity with common prototyping practices. These skills include (a) utilizing a 3-D printer in order to create the chassis, wheels, and sensor mounts, (b) disassembly, modification, and reassembly of two servo motors, and (c) assembly and soldering two custom-designed printed circuit boards ...


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