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Articles 91 - 105 of 105
Full-Text Articles in Engineering
Wind Loading On Trees Integrated With A Building Envelope, Aly Mousaad Aly, Alberto Zasso, Girma Bitsuamlak, Alberto Nicola Longarini, Arindam Gam Chowdhury
Wind Loading On Trees Integrated With A Building Envelope, Aly Mousaad Aly, Alberto Zasso, Girma Bitsuamlak, Alberto Nicola Longarini, Arindam Gam Chowdhury
Faculty Publications
With the sustainability movement, vegetated building envelopes are gaining more popularity. This requires special wind effect investigations, both from sustainability and resiliency perspectives. The current paper focuses on wind load estimation on small- and full-scale trees used as part of green roofs and balconies. Small-scale wind load assessment was carried out using wind tunnel testing in a global-effect study to understand the interference effects from surrounding structures. Full-scale trees were investigated at a large open-jet facility in a local-effect study to investigate the wind-tree interaction. The effect of Reynolds number combined with shape change on the overall loads measured at …
Applications Of High Throughput (Combinatorial) Methodologies To Electronic, Magnetic, Optical, And Energy-Related Materials, Martin L. Green, Ichiro Takeuchi, Jason R. Hattrick-Simpers
Applications Of High Throughput (Combinatorial) Methodologies To Electronic, Magnetic, Optical, And Energy-Related Materials, Martin L. Green, Ichiro Takeuchi, Jason R. Hattrick-Simpers
Faculty Publications
High throughput (combinatorial) materials science methodology is a relatively new research paradigm that offers the promise of rapid and efficient materials screening, optimization, and discovery. The paradigm started in the pharmaceutical industry but was rapidly adopted to accelerate materials research in a wide variety of areas. High throughput experiments are characterized by synthesis of a “library” sample that contains the materials variation of interest (typically composition), and rapid and localized measurement schemes that result in massive data sets. Because the data are collected at the same time on the same “library” sample, they can be highly uniform with respect to …
Capacity Fade Model For Spinel Limn2O4 Electrode, Yiling Dai, Long Cai, Ralph E. White
Capacity Fade Model For Spinel Limn2O4 Electrode, Yiling Dai, Long Cai, Ralph E. White
Faculty Publications
A mathematical model for the capacity fade of a LiMn2O4 (LMO) electrode is developed in this paper by including the acid attack on the active material and the solid electrolyte interphase (SEI) film formation on the LMO particle surface. The acid generated by the LiPF6 and the solvent decompositions are coupled to the manganese (Mn) dissolution. The decrease of the Li ion diffusion coefficient is involved as another contribution to the capacity fade, which is caused by the passive film formation on the active material surface. The effects of cell practical operation/fabrication conditions and kinetics of …
The Effect Of Isostatic Pressing On The Dielectric Properties Of Screen Printed Ba0.5Sr0.5Tio3 Thick Films, Siwei Wang, Lingling Zhang, Jiwei Zhai, Fanglin Chen
The Effect Of Isostatic Pressing On The Dielectric Properties Of Screen Printed Ba0.5Sr0.5Tio3 Thick Films, Siwei Wang, Lingling Zhang, Jiwei Zhai, Fanglin Chen
Faculty Publications
Ba0.5Sr0.5TiO3 thick films with B2O3–Li2O glass sintering aid were prepared by the screen printing method on Al2O3 substrates. A 200 MPa isostatic pressure was applied to the films before sintering. After being sintered at 950∘C, lower porosity and denser microstructure was obtained compared with the films without isostatic pressing. The dielectric constant and dielectric loss were 238 and 0.0028, respectively. A tunability of 61.7% was obtained for the isostatic pressed films, a 27.8% enhancement compared to unpressurized films. These results suggest that isostatic pressing …
Wave Propagation In Metamaterial Using Multiscale Resonators By Creating Local Anisotropy, Raiz U. Ahmed, Sourav Banerjee
Wave Propagation In Metamaterial Using Multiscale Resonators By Creating Local Anisotropy, Raiz U. Ahmed, Sourav Banerjee
Faculty Publications
Directional guiding, passing or stopping of elastic waves through engineered materials have many applications to the engineering fields. Recently, such engineered composite materials received great attention by the broader research community. In elastic waves, the longitudinal and transverse motion of material particles are coupled, which exhibits richer physics and demands greater attention than electromagnetic waves and acoustic waves in fluids. Waves in periodic media exhibit the property of Bragg scattering and create frequency band gaps in which the energy propagation is prohibited. However, in addition to the Bragg scattering, it has been found that local resonance of artificially designed resonators …
Techno- Economic Analysis Of Wastewater Biosolids Gasification, Jason M. Porter, Nick Lumley, Robert Braun, Tzahi Cath, Ana Prietro, Dotti Ramey, Greta Buschmann
Techno- Economic Analysis Of Wastewater Biosolids Gasification, Jason M. Porter, Nick Lumley, Robert Braun, Tzahi Cath, Ana Prietro, Dotti Ramey, Greta Buschmann
Faculty Publications
Wastewater treatment biosolids, commonly referred to as sludge, is a dilute suspension of micro-organisms, noxious organic matter, and mineral species in up to 99% water. Sludge is produced at about 250 mg/L of mixed municipal and light industrial wastewater treated. Management of this process stream can present a financial and environmental challenge for wastewater treatment plants (WWTPs), accounting for up to 15% of plant energy consumption. Operators of small urban WWTPs see the greatest challenge as their operations do not benefit from economies of scale, which permit larger facilities to absorb the costs or footprint of anaerobic digestion. This work …
Electrochemical Explanation For Asymmetric Electrowetting Response, Mehdi Khodayari, Nathan B. Crane, Alex A. Volinsky
Electrochemical Explanation For Asymmetric Electrowetting Response, Mehdi Khodayari, Nathan B. Crane, Alex A. Volinsky
Faculty Publications
In electrowetting, a droplet/substrate contact angle is modulated by applying a potential difference between the droplet and the substrate. Typically, the droplet potential is changed via an auxiliary electrode dipped in the droplet. Here, it is shown that electrochemical reactions lead to a potential drop on the auxiliary electrode in electrowetting, which degrades the droplet contact angle modulation. The magnitude of this effect depends on the voltage polarity. This problem can be addressed by using a dielectric layer, such as SiO2, which can prevent electrochemical reactions with the electrowetting substrate and the auxiliary electrode.
Analysis Of Integrated Engineering And Social Science Approaches For Projects In Developing Communities, Parry F. Garff, Eric C. Dahlin, Carol Ward, Randy Lewis
Analysis Of Integrated Engineering And Social Science Approaches For Projects In Developing Communities, Parry F. Garff, Eric C. Dahlin, Carol Ward, Randy Lewis
Faculty Publications
Current design methods such as appropriate technology, human-centered design, and participatory design are intended to generate development projects that resonate with users in communities in developing countries. These approaches are extremely useful, but often lack adequate documentation about how to collect data on and incorporate users feedback into the project’s design. To address this gap, we introduced social science research methods into a service-learning course for undergraduate engineering students, which culminated in a trip to the communities for whom they were designing, to help students incorporate user feedback into the design of their projects. This paper documents our efforts. One …
Supercritical Co2 Brayton Cycles For Solar-Thermal Energy, Brian D. Iverson, Thomas M. Conboy, James J. Pasch, Alan M. Kruizenga
Supercritical Co2 Brayton Cycles For Solar-Thermal Energy, Brian D. Iverson, Thomas M. Conboy, James J. Pasch, Alan M. Kruizenga
Faculty Publications
Of the mechanisms to improve efficiency for solar-‐thermal power plants, one of the most effective ways to improve overall efficiency is through power cycle improvements. As increases in operating temperature continue to be pursued, supercritical CO2 Brayton cycles begin to look more attractive despite the development costs of this technology. Further, supercritical CO2 Brayton has application in many areas of power generation beyond that for solar energy alone.
One challenge particular to solar-‐thermal power generation is the transient nature of the solar resource. This work illustrates the behavior of developmental Brayton turbomachinery in response to a fluctuating thermal input, much …
Final Report: Multipath Modeling And Mitigation Using Multiple Antennas (M4a), Michael Rice
Final Report: Multipath Modeling And Mitigation Using Multiple Antennas (M4a), Michael Rice
Faculty Publications
This report documents the effort under contract W900KK-09-C-0016. The contract comprised four phases spanning 15 April 2009 to 1 December 2012. The relationship between the effort associated with each phase and the contents of this report are as follows: Phase 1 was devoted exclusively to the channel sounding experiments with the UH-1H helicopter. The experimental setup, procedure, and results for the channel sounding experiments at Cairns Army Airfield and Patuxent River are described in Chapter 2. Good, usable data at upper L-band was captured during the Cairns Army Airfield experiments. Phase 2 was devoted to the channel sounding experiments with …
Characterization Of Macromolecular Structure Of Pyrolysis Products From A Colorado Green River Oil Shale, James L. Hillier, Thomas H. Fletcher, Mark S. Solum, Ronald J. Pugmire
Characterization Of Macromolecular Structure Of Pyrolysis Products From A Colorado Green River Oil Shale, James L. Hillier, Thomas H. Fletcher, Mark S. Solum, Ronald J. Pugmire
Faculty Publications
Volatile products from an oil shale from the Colorado Green River formation were studied by several methods. The oil shale was demineralized, and the resulting kerogen was also chemically analyzed. Both the oil shale and the demineralized kerogen were pyrolyzed at 10 K/min, and the pyrolysis products (light gas, tar, and char) were analyzed using 13C NMR, XPS, GC/MS, and FTIR. Low temperature ashing was performed in order to compare pyrolysis yields of oil shale and demineralized kerogen on a dry ash-free basis. Volatile yields of approximately 75% were achieved in an oil shale retort and 79% in the kerogen …
Coal Char-Co2 Gasification Measurements And Modeling In A Pressurized Flat-Flame Burner, Randy C. Shurtz, Thomas H. Fletcher
Coal Char-Co2 Gasification Measurements And Modeling In A Pressurized Flat-Flame Burner, Randy C. Shurtz, Thomas H. Fletcher
Faculty Publications
A pressurized flat-flame burner (PFFB) was used to conduct coal gasification studies. The PFFB was designed to provide an environment with laminar, dispersed entrained flow, with particle heating rates of ∼105 K/s, pressures of up to 15 atm, and gas temperatures of up to 2000 K. Residence times were varied from 30 to 700 ms in this study. Char gasification studies by CO2 were conducted on a subbituminous coal and 4 bituminous coals in the PFFB. Pressures of 5, 10, and 15 atm were used with gas compositions of 20, 40, and 90 mol % CO2. Gas conditions with peak …
Time-Dependent Deposition Characteristics Of Fine Coal Fly Ash In A Laboratory Gas Turbine Environment, Robert Laycock, Thomas H. Fletcher
Time-Dependent Deposition Characteristics Of Fine Coal Fly Ash In A Laboratory Gas Turbine Environment, Robert Laycock, Thomas H. Fletcher
Faculty Publications
Time-dependent deposition characteristics of fine coal fly ash were measured in the Turbine Accelerated Deposition Facility (TADF) at Brigham Young University. Two samples of subbituminous coal fly ash, with mass mean diameters of 3 and 13 microns, were entrained in a hot gas flow with a gas temperature of 1288 C and Mach number of 0.25. A nickel-based, superalloy metal coupon approximately 0.3 cm thick was held in a hot particle-laden gas stream to simulate deposition in a gas turbine. Tests were conducted with deposition times of 20, 40, and 60 min. Capture efficiencies and surface roughness characteristics (e.g., Ra) …
Solid-Fuel Regression Rate Modeling For Hybrid Rockets, Francesca Favaro, W. Sirignano, M. Manzoni, L. Deluca
Solid-Fuel Regression Rate Modeling For Hybrid Rockets, Francesca Favaro, W. Sirignano, M. Manzoni, L. Deluca
Faculty Publications
The regression rate of the solid fuel is a primary parameter in the performance analysis for a hybrid rocket. Many studies in the past few years have theoretically claimed, or experimentally shown, a dependence of the regression rate on the chamber total pressure. Such behavior is generally traced back to the presence of oxygen below the flame zone and of heterogeneous reactions occurring at the surface and affecting the pyrolysis law. An experimental program was performed at the Space Propulsion Laboratory of the Politecnico di Milano showing, within the explored operating conditions and the associated uncertainty bands, a neutral trend …
Prediction Of Sawdust Pyrolysis Yields From A Flat-Flame Burner Using The Cpd Model, Aaron D. Lewis, Thomas H. Fletcher
Prediction Of Sawdust Pyrolysis Yields From A Flat-Flame Burner Using The Cpd Model, Aaron D. Lewis, Thomas H. Fletcher
Faculty Publications
High heating rate pyrolysis experiments were performed on a softwood sawdust in a flat-flame burner reactor at temperatures from 1163 to 1433 K with particle residence times ranging from 23 to 102 ms at atmospheric pressure. Volatile yields of the 45−75 μm sawdust were measured and are believed to be similar to those that would occur in an industrial entrained-flow combustor or gasifier. A refractory tar yield near 1.5 wt % (dry, ash-free) was measured. A high percentage of the fully pyrolyzed sawdust char was spherical, having lost the original sawdust structure. It is suggested that the morphology of sawdust …