Engineering Commons^™

Formation Criterion For Binary Metal Diboride Solid Solutions Established Through Combinatorial Methods, Tongqi Wen, Beilin Ye, Honghua Liu, Shanshan Ning, Cai-Zhuang Wang, Yanhui Chu

Ames Laboratory Accepted Manuscripts

Establishing the formation criterion is urgent for accelerating the discovery and design of solid-solution materials with desirable properties. The previously reported formation criterion mainly focused on solid-solution alloys, while the formation criterion was rarely established in solid-solution ceramics. To solve this problem, herein, we take a class of solid-solution ceramics, namely binary metal diboride ((MxN1-x)B-2) solid solutions, as a prototype. Through combinatorial methods including high-throughput molten salt syntheses and high-throughput first-principles calculations combined with the machine learning approach, the correlation between influential factors, including atomic size difference (delta), mixing enthalpy at 0 K and 0 Pa (Delta Hmix0K), doping ...

Salt Mediated Self-Assembly Of Poly(Ethylene Glycol)-Functionalized Gold Nanorods, Hyeong Jin Kim, Wenjie Wang, Wei Bu, Md. Mir Hossen, Alejandra Londono-Calderon, Andrew C. Hillier, Tanya Prozorov, Surya Mallapragada, David Vaknin

Chemical and Biological Engineering Publications

Although challenging, assembling and orienting non-spherical nanomaterials into two- and three-dimensional (2D and 3D) ordered arrays can facilitate versatile collective properties by virtue of their shape-dependent properties that cannot be realized with their spherical counterparts. Here, we report on the self-assembly of gold nanorods (AuNRs) into 2D films at the vapor/liquid interface facilitated by grafting them with poly(ethylene glycol) (PEG). Using surface sensitive synchrotron grazing incidence small angle X-ray scattering (GISAXS) and specular X-ray reflectivity (XRR), we show that PEG-AuNRs in aqueous suspensions migrate to the vapor/liquid interface in the presence of salt, forming a uniform monolayer ...

Dynamic Response And Impact Energy Loss In Controlled Rocking Members, Dimitrios Kalliontzis, Sri Sritharan

Civil, Construction and Environmental Engineering Publications

Unbonded posttensioning anchors a rocking structural member to its foundation and produces its controlled rocking response when the member undergoes seismic action. Unlike rocking of free‐standing bodies, little attention has been given to the dynamic behavior of these controlled rocking members. This paper utilizes experiments of concrete structural members with unbonded posttensioning, varying member geometries, and levels of initial posttensioning force to (a) characterize the associated impact energy loss and (b) improve modeling of controlled rocking motions. Experimental results show that impact energy loss in controlled rocking members can be captured accurately using the coefficient of restitution (r) approach ...

Life-Cycle Assessment (Lca) Of Different Pretreatment And Product Separation Technologies For Butanol Bioprocessing From Oil Palm Frond, Nazira Mahmud, Kurt A. Rosentrater

Agricultural and Biosystems Engineering Publications

Environmental impact assessment is a crucial aspect of biofuels production to ensure that the process generates emissions within the designated limits. In typical cellulosic biofuel production process, the pretreatment and downstream processing stages were reported to require a high amount of chemicals and energy, thus generating high emissions. Cellulosic butanol production while using low moisture anhydrous ammonia (LMAA) pretreatment was expected to have a low chemical, water, and energy footprint, especially when the process was combined with more efficient downstream processing technologies. In this study, the quantification of environmental impact potentials from cellulosic butanol production plants was conducted with modeled ...

Identification Of An Ags2 Complex On Ag(110), Peter M. Spurgeon, Da-Jiang Liu, Junepyo Oh, Yousoo Kim, Patricia A. Thiel

Chemistry Publications

Adsorbed sulfur has been investigated on the Ag(110) surface at two different coverages, 0.02 and 0.25 monolayers. At the lower coverage, only sulfur adatoms are present. At the higher coverage, there are additional bright features which we identify as linear, independent AgS2 complexes. This identification is based upon density functional theory (DFT) and its comparison with experimental observations including bias dependence and separation between complexes. DFT also predicts the absence of AgS2 complexes at low coverage, and the development of AgS2 complexes around a coverage of 0.25 monolayers of sulfur, as is experimentally observed. To our ...

The First-Order Magnetoelastic Transition In Eu2in: A 151eu Mössbauer Study, D. H. Ryan, Durga Paudyal, Francois Guillou, Yaroslav Mudryk, Arjun K. Pathak, Vitalij K. Pecharsky

Ames Laboratory Accepted Manuscripts

Our ¹⁵¹Eu Mössbauer investigation of Eu₂In and Eu₂Sn shows that the europium in both materials is fully divalent. We confirm the distinct thermodynamic orders of the magnetic transitions and reveal a remarkable difference between the magnetic environments of the europium atoms in the two compounds. Possible structural and electronic origins for these differences are discussed using DFT calculations.

Managing Hysteresis Of Gd5si2ge2 By Magnetic Field Cycling, Anis Biswas, Yaroslav Mudryk, Arjun K. Pathak, Lin Zhou, Vitalij K. Pecharsky

Ames Laboratory Accepted Manuscripts

The influence of magnetic field cycling through the first-order magnetostructural transformation on the magnetic and magnetocaloric properties, as well as hysteresis of polycrystalline Gd5Si2Ge2, has been studied using magnetometry. The cycling has a minimal effect on the magnetic field-induced entropy change and the phase transformation temperature of the material. On the other hand, magnetic hysteresis decreases by 30% after approximately ten cycles and remains low unless the sample is moved far into the paramagnetic regime. Factors playing a role in the history dependence of hysteresis have been discussed.

A Test System For Ercot Market Design Studies: Development And Application, Swathi Battula, Leigh Tesfatsion, Thomas E. Mcdermott

Economics Working Papers

The ERCOT Test System developed in this study is an open-source library of Java/Python software classes, together with a synthetic grid construction method, specifically designed to facilitate the study of ERCOT market operations over successive days. In default form, these classes permit a high-level modeling of existing ERCOT market operations. Users can conduct a broad range of computational experiments under alternative parameter settings. In addition, users can readily extend these classes to model additional existing or envisioned ERCOT market features to suit different research purposes. An 8-bus test case is used to illustrate the capabilities of the test system ...

Synthesis And Characterization Of Rapidly-Degrading Polyanhydrides As Vaccine Adjuvants, Sean M. Kelly, Akash Mitra, Srishti Mathur, Balaji Narasimhan

Chemical and Biological Engineering Publications

There is a currently a need to develop adjuvants that are best suited to simultaneously enhance immune responses, induce immunologic memory, improve patient compliance (i.e., reduce doses and inflammation), and provide vaccine shelf stability for stockpiling and global deployment to challenging environments. Biodegradable polyanhydrides have been investigated extensively to overcome such challenges. It has been shown that controlling copolymer composition can result in chemistry-dependent immunomodulatory capabilities. These studies have revealed that copolymers rich in sebacic acid (SA) are highly internalized by antigen presenting cells and confer improved shelf stability of encapsulated proteins, while copolymers rich in 1,8-bis(p-carboxyphenoxy ...

Structure-Performance Correlations Of Cross-Linked Boronic Acid Polymers As Adsorbents For Recovery Of Fructose From Glucose–Fructose Mixtures, Guido Schroer, Jeff Deischter, Tobias Zensen, Jan Kraus, Ann-Christin Pöppler, Long Qi, Susannah Scott, Irina Delidovicha

Ames Laboratory Accepted Manuscripts

Recovery of bio-oxygenates from reaction mixtures is one of the major challenges for future bio-refineries. Isolation of fructose produced by isomerization of glucose presents a typical example at a very early stage of the value chain. We propose to recover fructose from a solution containing a mixture of glucose and fructose by adsorption on polymers bearing phenylboronate moieties. p-Vinylphenylboronic acid was polymerized with various cross-linkers, namely polar aliphatic, low-polarity aliphatic, and aromatic. The cross-linker content was in the range 5–40 mol%. The polymers exhibit high capacities for fructose, with a maximum loading of up to 1 molFru molB ...

Common Secondary And Tertiary Structural Features Of Aptamer–Ligand Interaction Shared By Rna Aptamers With Different Primary Sequences, Muslum Ilgu, Shuting Yan, Ryan M. Khounlo, Monica H. Lamm, Marit Nilsen-Hamilton

Chemical and Biological Engineering Publications

Aptamer selection can yield many oligonucleotides with different sequences and affinities for the target molecule. Here, we have combined computational and experimental approaches to understand if aptamers with different sequences but the same molecular target share structural and dynamical features. NEO1A, with a known NMR-solved structure, displays a flexible loop that interacts differently with individual aminoglycosides, its ligand affinities and specificities are responsive to ionic strength, and it possesses an adenosine in the loop that is critical for high-affinity ligand binding. NEO2A was obtained from the same selection and, although they are only 43% identical in overall sequence, NEO1A and ...

Midwestern Cropping System Effects On Drainage Water Quality And Crop Yields, Brian W. Dougherty, Carl H. Pederson, Antonio P. Mallarino, Daniel S. Andersen, Michelle L. Soupir, Ramesh S. Kanwar, Matthew J. Helmers

Agricultural and Biosystems Engineering Publications

Grain producers are challenged to maximize crop production while utilizing nutrients efficiently and minimizing negative impacts on water quality. There is a particular concern about nutrient export to the Gulf of Mexico via loss from subsurface drainage systems. The objective of this study was to investigate the effects of crop rotation, tillage, crop residue removal, swine manure applications, and cereal rye (Secale cereale) cover crops on nitrate‐N (NO3‐N) and Total Reactive P (TRP) loss via subsurface drainage. The study was evaluated from 2008 through 2015 using thirty‐six 0.4‐ha plots outfitted with a subsurface drainage water ...

Highly Reactive Energetic Films By Pre-Stressing Nano-Aluminum Particles, Michael N. Bello, Alan M. Williams, Valery I. Levitas, Nobumichi Tamura, Daniel K. Unruh, Juliusz Warzywoda, Michelle L. Pantoya

Aerospace Engineering Publications

Energetic films were synthesized using stress altered nano-aluminum particles (nAl). The nAl powder was pre-stressed to examine how modified mechanical properties of the fuel particles influenced film reactivity. Pre-stressing conditions varied by quenching rate. Slow and rapid quenching rates induced elevated dilatational strain within the nAl particles that was measured using synchrotron X-ray diffraction (XRD). An analytical model for stress and strain in a nAl core–Al2O3 shell particle that includes creep in the shell and delamination at the core–shell boundary, was developed and used for interpretation of strain measurements. Results show rapid quenching induced 81% delamination at the ...

A Deep Learning Framework For Design And Analysis Of Surgical Bioprosthetic Heart Valves, Aditya Balu, Sahiti Nallagonda, Fei Xu, Adarsh Krishnamurthy, Ming-Chen Hsu, Soumik Sarkar

Mechanical Engineering Publications

Bioprosthetic heart valves (BHVs) are commonly used as heart valve replacements but they are prone to fatigue failure; estimating their remaining life directly from medical images is difficult. Analyzing the valve performance can provide better guidance for personalized valve design. However, such analyses are often computationally intensive. In this work, we introduce the concept of deep learning (DL) based finite element analysis (DLFEA) to learn the deformation biomechanics of bioprosthetic aortic valves directly from simulations. The proposed DL framework can eliminate the time-consuming biomechanics simulations, while predicting valve deformations with the same fidelity. We present statistical results that demonstrate the ...

A Transactive Energy Approach To Distribution System Design: Household Formulation, Swathi Battula, Leigh Tesfatsion, Zhaoyu Wang

Economics Working Papers

A household model is formulated to facilitate careful development and performance testing of bid-based transactive energy system (TES) designs with voluntary customer participation. The optimal general bid-function form for households with thermostatically controlled loads is derived from dynamic programming principles, based solely on general household thermal dynamic and welfare attributes. Quantitative forms are determined for these optimal bid functions, given quantitative forms for these attributes. These quantitative attributes are used to construct representative household types based on clusterings of correlated parameter values. Bid comparison, peak-load reduction, and load-matching test cases conducted for a 123-bus distribution system operating under a generic ...

Development Of A Semi-Empirical Potential Suitable For Molecular Dynamics Simulation Of Vitrification In Cu-Zr Alloys, Mikhail Mendelev, Yang Sun, Feng Zhang, Cai-Zhuang Wang, Kai-Ming Ho

Ames Laboratory Accepted Manuscripts

The fast increase in available computation power allowed us to decrease the cooling rate in molecular dynamics (MD) simulation of vitrification by several orders of magnitude. While the reliability of the MD simulation should obviously benefit from this increase in the computational power, in some cases, it led to unexpected results. In particular, Ryltsev et al. [J. Chem. Phys. 149, 164502 (2018)] found that the most popular potentials for the Cu-Zr and Cu-Zr-Al alloys from Mendelev et al. [Philos. Mag. 89, 967 (2009)] and Cheng et al. [Phys. Rev. Lett. 102, 245501 (2009)] do not actually describe good glass forming ...

Optimizing Composition In Mnbi Permanent Magnet Alloys, Brandt A. Jensen, Wei Tang, Xubo Liu, Alexandra I. Nolte, Gaoyuan Ouyang, Kevin W. Dennis, Jun Cui

Ames Laboratory Accepted Manuscripts

MnBi is an attractive rare-earth-free permanent magnetic material due to its low materials cost, high magnetocrystalline anisotropy (1.6 × 106 J m−3), and good magnetization (81 emu g−1) at room temperature. Although the theoretical maximum energy product (BH)max of 20 MGOe is lower than that of NdFeB-based magnets, the low temperature phase (LTP) of MnBi has a positive temperature coefficient of coercivity, up to 200 °C, which makes it a potential candidate for high temperature applications such as permanent magnet motors. However, the oxygen sensitivity of the MnBi compound and the peritectic reaction between Mn and Bi ...

Characterization Of Ordering In Fe-6.5%Si Alloy Using X-Ray, Tem, And Magnetic Tga Methods, Gaoyuan Ouyang, Brandt Jensen, Chad R. Macziewski, Tao Ma, Fanqiang Meng, Qishen Lin, Lin Zhou, Matthew J. Kramer, Jun Cui

Ames Laboratory Accepted Manuscripts

Fe-6.5wt%Si steel surpasses the current extensively used Fe-3.2wt%Si steel in lower iron loss, higher permeability, and near zero magnetostriction. As a cost effective soft magnetic material, Fe-6.5wt%Si may find applications in motors, transformers, and electronic components. However, the brittleness of the alloy poses processing challenges. The brittleness in Fe-6.5wt%Si is attributed to the formation of ordered phases. Evaluation of the amount of ordered phases is important for the research and development of Fe-6.5wt%Si. This paper aims to find effective ways to evaluate the ordering degree through a comparison of various ...

Assessing Plant Performance In The Enviratron, Yin Bao, Scott Zarecor, Dylan Shah, Taylor Tuel, Darwin A. Campbell, Antony V. E. Chapman, David Imberti, Daniel Kiekhaefer, Henry Imberti, Thomas Lubberstedt, Yanhai Yin, Dan Nettleton, Carolyn J. Lawrence-Dill, Steven A. Whitham, Lie Tang, Stephen H. Howell

Agricultural and Biosystems Engineering Publications

Background: Assessing the impact of the environment on plant performance requires growing plants under controlled environmental conditions. Plant phenotypes are a product of genotype × environment (G × E), and the Enviratron at Iowa State University is a facility for testing under controlled conditions the effects of the environment on plant growth and development. Crop plants (including maize) can be grown to maturity in the Enviratron, and the performance of plants under different environmental conditions can be monitored 24 h per day, 7 days per week throughout the growth cycle.

Results: The Enviratron is an array of custom-designed plant growth chambers that ...

Decision Making Under Uncertainty For Design Of Resilient Engineered Systems, Cameron A. Mackenzie, Chao Hu

Industrial and Manufacturing Systems Engineering Publications

Designing resilient engineered systems that can sense and withstand adverse events and recover from the effects of the adverse events is increasingly seen as an important goal of engineering design. This paper proposes a value-driven design for resilience (VD2R) framework in order to enable the assessment of system resilience and the optimization of decision variables (or design characteristics) that maximize the value of the system for a firm. The VD2R framework possesses three unique features that allow system resilience and value to be addressed in a theoretically founded and explicit way. First, it assesses the time-dependent resilience of an engineered ...

Linkage Disequilibrium Mapping Of High-Throughput Image-Derived Descriptors Of Plant Architecture Traits Under Field Conditions, Matthew W. Breitzman, Yin Bao, Lie Tang, Patrick S. Schnable, Maria G. Salas-Fernandez

Agronomy Publications

Plant architectural traits are important factors in determining grain and biomass productivity of sorghum (Sorghum bicolor (L) Moench). However, collecting data on these architectural traits is labor-intensive and time-consuming, especially when using numerous lines in quantitative genetic studies or breeding programs. Therefore, we used the high-throughput field-based robotic platform PhenoBot 1.0 to collect whole canopy stereo images from a large association mapping panel under field conditions. These images were used to create a plot-based 3D reconstruction of the canopy from which phenotypic features were automatically extracted. These features included: plot-based plant height (PPH), plot-based plant width (PPW), plant surface ...

Microstructure Evolution During Near-Tg Annealing And Its Effect On Shear Banding In Model Alloys, Meng-Hao Yang, Bei Cai, Yang Sun, Feng Zhang, Yi-Fan Wang, Cai-Zhuang Wang, Kai-Ming Ho

Ames Laboratory Accepted Manuscripts

By performing extensive molecular dynamics simulations, we investigate the deformation behavior in Al90Sm10 and Cu64.5Zr35.5 alloys after elongated isothermal annealing in the vicinity of the glass-transition temperature (Tg). Different microstructural response to the annealing process was observed: Al90Sm10 maintains the glassy structure with improved energetic stability, enhanced short-range order (SRO), and a more pronounced spatial network that extends beyond the first atomic shell, while Cu64.5Zr35.5 forms nanocrystalline Laves Cu2Zr phases. Shear banding occurs in both annealed systems under shear loading. For Al90Sm10, the spatial network formed by the local clusters characterizing the SRO of the system ...

Viscoelastic Properties Of Shock Wave Exposed Brain Tissue Subjected To Unconfined Compression Experiments, Annastacia K. Mccarty, Ling Zhang, Sarah Hansen, William J. Jackson, Sarah A. Bentil

Mechanical Engineering Publications

Traumatic brain injuries (TBI) affect millions of people each year. While research has been dedicated to determining the mechanical properties of the uninjured brain, there has been a lack of investigation on the mechanical properties of the brain after experiencing a primary blast-induced TBI. In this paper, whole porcine brains were exposed to a shock wave to simulate blast-induced TBI. First, ten (10) brains were subjected to unconfined compression experiments immediately following shock wave exposure. In addition, 22 brains exposed to a shock wave were placed in saline solution and refrigerated between 30 minutes and 6.0 hours before undergoing ...

Fatigue-Resistant High-Performance Elastocaloric Materials Made By Additive Manufacturing, Huilong Hou, Emrah Simsek, Tao Ma, Nathan S. Johnson, Suxin Qian, Cheikh Cissé, Drew Stasak, Naila Al Hasan, Lin Zhou, Yunho Hwang, Reinhard Radermacher, Valery I. Levitas, Matthew J. Kramer, Mohsen Asle Zaeem, Aaron P. Stebner, Ryan T. Ott, Jun Cui, Ichiro Takeuchi

Aerospace Engineering Publications

Elastocaloric cooling, a solid-state cooling technology, exploits the latent heat released and absorbed by stress-induced phase transformations. Hysteresis associated with transformation, however, is detrimental to efficient energy conversion and functional durability. We have created thermodynamically efficient, low-hysteresis elastocaloric cooling materials by means of additive manufacturing of nickel-titanium. The use of a localized molten environment and near-eutectic mixing of elemental powders has led to the formation of nanocomposite microstructures composed of a nickel-rich intermetallic compound interspersed among a binary alloy matrix. The microstructure allowed extremely small hysteresis in quasi-linear stress-strain behaviors—enhancing the materials efficiency by a factor of four to ...

An Immersogeometric Formulation For Free-Surface Flows With Application To Marine Engineering Problems, Qiming Zhu, Fei Xu, Songzhe Xu, Ming-Chen Hsu, Jinhui Yan

Mechanical Engineering Publications

An immersogeometric formulation is proposed to simulate free-surface flows around structures with complex geometry. The fluid–fluid interface (air–water interface) is handled by the level set method, while the fluid–structure interface is handled through an immersogeometric approach by immersing structures into non-boundary-fitted meshes and enforcing Dirichlet boundary conditions weakly. Residual-based variational multiscale method (RBVMS) is employed to stabilize the coupled Navier–Stokes equations of incompressible flows and level set convection equation. Other level set techniques, including re-distancing and mass balancing, are also incorporated into the immersed formulation. Adaptive quadrature rule is used to better capture the geometry of ...

New Materials Physics, Paul C. Canfield

Ames Laboratory Accepted Manuscripts

This review presents a survey of, and guide to, new materials physics (NMP) research. It begins with an overview of the goals of NMP and then presents important ideas and techniques for the design and growth of new materials. An emphasis is placed on the use of compositional phase diagrams to inform and motivate solution growth of single crystals. The second half of this review focuses on the vital process of generating actionable ideas for the growth and discovery of new materials and ground states. Motivations ranging from (1) wanting a specific compound, to (2) wanting a specific ground state ...

Headland Turning Optimisation For Agricultural Vehicles And Those With Towed Implements, Xuyong Tu, Lie Tang

Agricultural and Biosystems Engineering Publications

As an essential part of field coverage path planning process, mobile agricultural field equipment headland turning is a process that should be done in a manner that can maximise the equipment’s operational efficiency through minimising the time or travel distance during the turning. However, this headland turning trajectory optimisation task represents a challenging dynamic nonlinear optimisation problem which is difficult to solve by using traditional indirect numerical methods. In this research, we investigated the possibility of using direct numerical methods to solve such a nonlinear optimisation problem in a restricted parameter neighborhood with constraints. We developed the kinematic models ...

Machine Learning Approach For Prescriptive Plant Breeding, Kyle A. Parmley, Race H. Higgins, Baskar Ganapathysubramanian, Soumik Sarkar, Asheesh K. Singh

Mechanical Engineering Publications

We explored the capability of fusing high dimensional phenotypic trait (phenomic) data with a machine learning (ML) approach to provide plant breeders the tools to do both in-season seed yield (SY) prediction and prescriptive cultivar development for targeted agro-management practices (e.g., row spacing and seeding density). We phenotyped 32 SoyNAM parent genotypes in two independent studies each with contrasting agro-management treatments (two row spacing, three seeding densities). Phenotypic trait data (canopy temperature, chlorophyll content, hyperspectral reflectance, leaf area index, and light interception) were generated using an array of sensors at three growth stages during the growing season and seed ...

Pilot-Scale Assessment Of A Novel Farrowing Creep Area Supplementary Heat Source, Benjamin C. Smith, Brett C. Ramirez, Steven J. Hoff, Laura L. Greiner

Agricultural and Biosystems Engineering Publications

Pre-weaning morality (PWM) is attributed to a poor creep area microclimate and causes major economic and productivity losses for the US swine industry. Piglets need supplementary heat to overcome a high surface area to body weight ratio and minimal thermoregulation. A pilot-scale study was conducted to evaluate a semi-enclosed heated microclimate (SEHM) as a supplementary heat source for farrowing creep areas over six farrowing cycles (from January to July 2019) in two rooms with 24 farrowing stalls in each room. Six SEHMs (each SEHM covers two stalls) were randomly distributed to each room and compared to heat lamps (HLs) for ...

Chameleon Metals: Autonomous Nano‐Texturing And Composition Inversion On Liquid Metals Surfaces, Andrew Martin, Winnie Kiarie, Boyce Chang, Martin Thuo

Materials Science and Engineering Publications

Studies on passivating oxides on liquid metals are challenging, in part, due to plasticity, entropic, and technological limitations. In alloys, compositional complexity in the passivating oxide(s) and underlying metal interface exacerbates these challenges. This nanoscale complexity, however, offers an opportunity to engineer the surface of the liquid metal under felicitous choice of processing conditions. We inferred that difference in reactivity, coupled with inherent interface ordering, presages exploitable order and selectivity to autonomously present compositionally biased oxides on the surface of these metals. Besides the compositional differences, sequential release of biased (enriched) components, via fractal‐like paths, allows for patterned ...