Materials Science and Engineering Commons^™

Development Of Carbon Fiber-Modified Electrically Conductive Concrete For Implementation In Des Moines International Airport, Alireza Sassani, Halil Ceylan, Sunghwan Kim, Ali Arabzadeh, Peter C. Taylor, Kasthurirangan Gopalakrishnan

Civil, Construction and Environmental Engineering Publications

This paper reports on the procedures of mix design preparation, production, placement, and performance evaluation of the first electrically conductive concrete (ECON) heated-pavement system (HPS) implemented at a U.S. airport. While ECON has drawn considerable attention as a paving material for multi-functional pavements, including HPS, the majority of ECON HPS applications and studies have been limited to laboratory scale or include materials/methods that do not conform to regulations enforced by airfield construction practices. Carbon fiber-reinforced ECON provides a promising prospective for application in airfield pavements. In this study, ECON mixtures were prepared in the laboratory using varying cementitious ...

Open Source 3d Printers: An Appropriate Technology For Building Low Cost Optics Labs For The Developing Communities, Jephias Gwamuri, Joshua M. Pearce

Joshua M. Pearce

The recent introduction of RepRap (self-replicating rapid prototyper) 3-D printers and the resultant open source technological improvements have resulted in affordable 3-D printing, enabling low-cost distributed manufacturing for individuals. This development and others such as the rise of open source-appropriate technology (OSAT) and solar powered 3-D printing are moving 3-D printing from an industry based technology to one that could be used in the developing world for sustainable development. In this paper, we explore some specific technological improvements and how distributed manufacturing with open-source 3-D printing can be used to provide open-source 3-D printable optics components for developing world communities ...

3-D Printing Open-Source Click-Muac Bands For Identification Of Malnutrition, Ross Michaels, Joshua M. Pearce

Joshua M. Pearce

No abstract provided.

Model-Assisted Approach For Probability Of Detection (Pod) In High-Temperature Ultrasonic Nde Using Low-Temperature Signals, Prathamesh N. Bilgunde, Leonard J. Bond

Aerospace Engineering Publications

Advanced piezoelectric-based ultrasonic transducers offer the potential for in-coolant nondestructive testing (NDT) measurements at high temperatures (HTs), including during hot standby (~260°C) for liquid-sodium–cooled advanced small modular reactors. The reliability of the NDT measurements is typically quantified by the probability of detection (POD) measured at the corresponding temperature. Obtaining such data in liquid sodium is challenging. Using a model-assisted POD approach, a transfer function is reported that enables data obtained on low carbon steel specimens at room temperature to give an estimated POD at an HT. A primary source of the difference in POD between room temperature and ...

Plastic Response Of Dislocation Glide In Solid Helium Under Dc Strain-Rate Loading, Caizhi Zhou, Jungjung Su, Matthias J. Graf, Charles J. Olson Reichhardt, Alexander V. Balatsky, Irene J. Beyerlein

Caizhi Zhou

We develop a model for the gliding of dislocations and plasticity in solid ⁴He. This model takes into account the Peierls barrier, multiplication and interaction of dislocations, as well as classical thermally and mechanically activated processes leading to dislocation glide. We specifically examine the dc stress-strain curve and how it is affected by temperature, strain rate, and dislocation density. As a function of temperature and shear strain, we observe plastic deformation and discuss how this may be related to the experimental observation of elastic anomalies in solid hcp ⁴He that have been discussed in connection with the possibility ...

Comment On "Giant Plasticity Of A Quantum Crystal", Caizhi Zhou, Charles J. Olson Reichhardt, Matthias J. Graf, Jungjung Su, Alexander V. Balatsky, Irene J. Beyerlein

Caizhi Zhou

In their Letter, Haziot et al. report a novel phenomenon of giant plasticity for hcp 4He quantum crystals. They assert that 4He exhibits mechanical properties not found in classical plasticity theory. Specifically, they examine high-quality crystals as a function of temperature T and applied strain ϵapp, where the shear modulus µ =Tapp/ϵapp reaches a plateau and dissipation 1=Q becomes close to zero; both quantities are reported to be independent of applied stress Tapp and strain ϵapp, implying a reversible dissipation process and suggesting dislocation motion by quantum tunneling. At lower T, an increase in µ and 1/Q ...

Photoactuated Pens For Molecular Printing, Zhongjie Huang, Le Li, Xu A. Zhang, Nourin Alsharif, Xiaojian Wu, Zhiwei Peng, Xiyuan Cheng, Peng Wang, Keith A. Brown, Yuhuang Wang

Xu Zhang

Magnetic Two-Way Valves For Paper-Based Capillary-Driven Microfluidic Devices, Mario Fratzl, Boyce Chang, Stephanie Oyola-Reynoso, Guillaume Blaire, Sarah Delshad, Thibaut Devillers, Thomas Ward, Iii, Nora M. Dempsey, Jean-Francis Bloch, Martin M. Thuo

Materials Science and Engineering Publications

This article presents a magnetically actuated two-way, three-position (+, 0, −), paper-based microfluidic valve that includes a neutral position (0)--the first of its kind. The system is highly robust, customizable, and fully automated. The advent of a neutral position and the ability to precisely control switching frequencies establish a new platform for highly controlled fluid flows in paper-based wicking microfluidic devices. The potential utility of these valves is demonstrated in automated, programmed, patterning of dyed liquids in a wicking device akin to a colorimetric assay but with a programmed fluid/reagent delivery. These valves are fabricated using facile methods and thus ...

Room-Temperature Homogeneous Nucleation Synthesis And Thermal Stability Of Nanometer Single Crystal Ceo2, X.-D. Zhou, Wayne Huebner, Harlan U. Anderson

Wayne Huebner

Nanometer (about 4~5nm) CeO2 single crystals were first synthesized by room-temperature homogeneous nucleation; the size was determined by electron microscopy and specific surfaced area of the particles. Modeling revealed that the surface energy of as-synthesized nanometer single crystals was in the range of 2.8-3.7J/m2. Crystal growth mechanisms change over the temperature regimes, from boundary diffusion over low-temperature regime (Eα=0.16eV) to bulk diffusion (Eα=0.50eV) over high-temperature region.

Hedgehog Spin-Vortex Crystal Stabilized In A Hole-Doped Iron-Based Superconductor, William R. Meier, Qing-Ping Ding, Andreas Kreyssig, Sergey Bud’Ko, Aashish Sapkota, Karunakar Kothapalli, Vladislav Borisov, Roser Valentí, Cristian D. Batista, Peter Orth, Rafael M. Fernandes, Alan I. Goldman, Yuji Furukawa, Anna E. Böhmer, Paul C. Canfield

Ames Laboratory Accepted Manuscripts

Magnetism is widely considered to be a key ingredient of unconventional superconductivity. In contrast to cuprate high-temperature superconductors, antiferromagnetism in most Fe-based superconductors (FeSCs) is characterized by a pair of magnetic propagation vectors, (π,0) and (0,π). Consequently, three different types of magnetic order are possible. Of these, only stripe-type spin-density wave (SSDW) and spin-charge-density wave (SCDW) orders have been observed. A realization of the proposed spin-vortex crystal (SVC) order is noticeably absent. We report a magnetic phase consistent with the hedgehog variation of SVC order in Ni-doped and Co-doped CaKFe 4As 4 based on thermodynamic, transport, structural and ...

Pm Manufacturing Research Boosted By Continuous Sintering Furnace, Joseph William Newkirk

Joseph William Newkirk

University of Missouri-Rolla has recently acquired a Fluidtherm laboratory continuous sintering furnace. Custom designed and built for PM research, the furnace will allow current efforts in sintering development, pressure gas quenching of PM steels, optimisation of toughness and fatigue properties of PM parts, and production of metal matrix composites to be enhanced and extended.

Comparison Of Thermal Properties Of Laser Deposition And Traditional Welding Process Via Thermal Diffusivity Measurement, Yu Yang, Omoghene Osaze Obahor, Yaxin Bao, Todd E. Sparks, Jianzhong Ruan, Jacquelyn K. Stroble, Robert G. Landers, Frank W. Liou, Joseph William Newkirk

Joseph William Newkirk

Laser deposition is an effective process for mold and die repair. In order to improve the part repair quality??the process impact on thermal diffusivity and thermal conductivity needs to be understood for laser deposited, welded and virgin H13. In this paper, H13 tool steel samples were made by laser deposition, welding and virgin H13 and then cut into pieces. Experiments were conducted to investigate the thermal diffusivity and conductivity. A laser flash method is used to test these samples. The future work and opportunities are also summarized. Keywords: Laser Flash, laser deposition, tool steel, H13

Corrosion Resistant Nickel-Based Alloy, Joseph William Newkirk, Sanhong Zhang

Joseph William Newkirk

A nickel based, high silicon alloy exhibits very high corrosion resistance in high temperature sulfuric acid environments. The alloy may be cast and is sufficiently ductile to be fabricated and machined. The alloy is ductile and has sufficient resistance to mechanical and thermal shock to be reliable in service when used as rotating parts.

An Investigation Of The Effect Of Direct Metal Deposition Parameters On The Characteristics Of The Deposited Layers, Tarak A. Amine, Joseph William Newkirk, Frank W. Liou

Joseph William Newkirk

Multilayer direct laser deposition (DLD) is a fabrication process through which parts are fabricated by creating a molten pool into which metal powder is injected as particles. During fabrication, complex thermal activity occurs in different regions of the build; for example, newly deposited layers will reheat previously deposited layers. The objective of this study was to provide insight into the thermal activity that occurs during the DLD process. This work focused on the effect of the laser parameters of newly deposited layers on the microstructure and mechanical properties of the previously deposited layers in order to characterize these effects to ...

Magnetic Properties Of Gd Intermetallics, L. Petit, Z. Szotek, J. Jackson, M. Lüders, Durga Paudyal, Yaroslav Mudryk, Vitalij K. Pecharsky, K. A. Gschneidner, J. B. Staunton

Ames Laboratory Accepted Manuscripts

Using first-principles calculations, based on disordered local moment theory, combined with the self-interaction corrected local spin density approximation, we study magnetic interactions in GdX intermetallics for X = Cu, Zn, Ga, Cd, and Mg. Our predicted magnetic orders and ordering temperatures both at zero and other pressures agree well with experiments including the large increase in the Curie temperature of GdCd under pressure that is shown by our own experimental measurements. From our results it emerges that the Ruderman-Kittel-Kasuya-Yosida interaction on its own can not explain the observed behaviour under pressure, and that the magnetic ordering mechanism is strongly influenced by ...

Influence Of Classical Anisotropy Fields On The Properties Of Heisenberg Antiferromagnets Within Unified Molecular Field Theory, Tey Lamichhane, Valentin Taufour, Andriy Palasyuk, Qisheng Lin, Sergey Bud’Ko, Paul C. Canfield

Ames Laboratory Accepted Manuscripts

We report on the synthesis of single-crystal and polycrystalline samples of Ce 3 − x Mg x Co 9 solid solution ( 0 ≤ x ≲ 1.4 ) and characterization of their structural and magnetic properties. The crystal structure remains rhombohedral in the whole composition range and Mg partially replaces Ce in the 6 c site of the CeCo 3 structure. Ferromagnetism is induced by Mg substitutions starting as low as x = 0.18 and reaching a Curie temperature as high as 450 K for x = 1.35 . Measurements on single crystals with x = 1.34 and T C = 440     K indicate an axial ...

Doping Evolution Of The Second Magnetization Peak And Magnetic Relaxation In (Ba1−Xkx)Fe2as2 Single Crystals, Yong Liu, Lin Zhou, Kewei Sun, Warren E. Straszheim, Makariy A. Tanatar, Ruslan Prozorov, Thomas A. Lograsso

Ames Laboratory Accepted Manuscripts

We present a thorough study of doping dependent magnetic hysteresis and relaxation characteristics in single crystals of ( B a 1 − x K x ) F e 2 A s 2 ( 0.18 ≤ x ≤ 1 ). The critical current density J c reaches maximum in the underdoped sample x = 0.26 and then decreases in the optimally doped and overdoped samples. Meanwhile, the magnetic relaxation rate S rapidly increases and the flux creep activation barrier U 0 sharply decreases in the overdoped sample x = 0.70 . These results suggest that vortex pinning is very strong in the underdoped regime, but it is greatly ...

Propeller Design Requirements For Quadcopters Utilizing Variable Pitch Propellers, Ian R. Mcandrew, Elena Navarro, Ken Witcher

Publications

Unmanned aerial vehicles, UAV, has increases in the drastically in these past several years since their costs reduced. This research is based and built upon previous research presented in a conference. With the advent of commercial Quadcopters, four propeller systems, are used, being designed and used to operate the advantages of both flight and hovering. The basic design of their propeller blades has not evolved from the early days of manned flight when wooden fixed blades were used. In this paper that expands upon previous findings and discussions it explores the historical developments. Furthermore, how the expansion and reduction in ...

Effect Of Stacking Fault Energy On Mechanism Of Plastic Deformation In Nanotwinned Fcc Metals, Valery Borovikov, Mikhail I. Mendelev, Alexander H. King, Richard A. Lesar

Richard Alan Lesar

Starting from a semi-empirical potential designed for Cu, we have developed a series of potentials that provide essentially constant values of all significant (calculated) materials properties except for the intrinsic stacking fault energy, which varies over a range that encompasses the lowest and highest values observed in nature. These potentials were employed in molecular dynamics (MD) simulations to investigate how stacking fault energy affects the mechanical behavior of nanotwinned face-centered cubic (FCC) materials. The results indicate that properties such as yield strength and microstructural stability do not vary systematically with stacking fault energy, but rather fall into two distinct regimes ...

Modeling Of Ti-W Solidification Microstructures Under Additive Manufacturing Conditions, Matthew R. Rolchigo, Michael Mendoza, Peyman Samimi, David A. Brice, Peter C. Collins, Richard Lesar

Richard Alan Lesar

Additive manufacturing (AM) processes have many benefits for the fabrication of alloy parts, including the potential for greater microstructural control and targeted properties than traditional metallurgy processes. To accelerate utilization of this process to produce such parts, an effective computational modeling approach to identify the relationships between material and process parameters, microstructure, and part properties is essential. Development of such a model requires accounting for the many factors in play during this process, including laser absorption, material addition and melting, fluid flow, various modes of heat transport, and solidification. In this paper, we start with a more modest goal, to ...