Aviation Research Division

Atlantic City, United States

Aviation Research Division

Atlantic City, United States

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Huang C.,University of Central Florida | Huang C.,Aviation Research Division | Bunmi Odetola C.,University of Central Florida | Bunmi Odetola C.,University of Ontario Institute of Technology | And 2 more authors.
Applied Catalysis A: General | Year: 2015

Pulse electroplating technology has been applied in the preparation of Pt/C electrocatalysts for hydrogen fuel cell electrodes for decades. The major challenge remaining unsolved is the aggregation of Pt nanoparticles on the carbon support. This research reports a nanoparticle seeded pulse electroplating method for preparing Pt/C electrocatalysts used for oxygen reduction reaction (ORR). Pt or Pt alloy nanoparticles were pre-deposited onto a carbon support as nuclei, followed by Pt pulse electrodeposition. This new approach is able to overcome Pt particle aggregation issues and improve catalyst performance. The technology can also be used for the preparation of core/shell Pt/C electrodes when non-Pt or Pt alloy nanoparticles are used as seeding materials. Experimental results show that a Pt/C electrode with less than 0.1 mg/cm2 Pt loading density, synthesized based on 3.0 nm Pt nanoparticle seeds, can achieve a higher ORR activity than a commercial electrode with 0.5 mg/cm2 Pt loading. When Pt-Pd-Ru alloy nanoparticles of 2.0 nm average diameter were used as seeding nuclei the prepared Pt/C electrode showed higher ORR performance than the commercial electrode, further reduced Pt loading density. Atomic level STEM analyses showed that numerous free Pt atoms were surrounding Pt nanoparticles, serving as nuclei. The seeding atoms, along with nanoparticles, promote the even growth of Pt particles on carbon support during electroplating. This result is verified by SEM images which indicate that electroplated Pt particles on the carbon surface are uniformly distributed and each particle is loosely packed with Pt nanosized flakes. The flower-like structure, with higher surface areas, enhances mass transfer rates and leads to higher ORR efficiencies. Although a commercial Pt/C electrode was used as a baseline catalyst for comparing prepared electrodes, this exploratory research was based on a rotational disk electrode. Fuel cell testing is needed to confirm the finding.


Oztekin A.,Hi Tec Systems Inc | Oztekin A.,Aviation Research Division
15th AIAA Aviation Technology, Integration, and Operations Conference | Year: 2015

This paper introduces a Facility Risk Assessment Tool (FRAT) to perform data-driven, risk-based assessment of Air Traffic Control (ATC) facilities. FRAT facilitates comparative analysis of facilities within a control group, trending facility performance over time, and drill-down analysis of facility data underlying emerging safety trends to proactively manage risk by assigning oversight resources towards facilities with the highest priority. FRAT calculates quantitative ratings for an ATC facility modeled as an influence network using a set of risk factors. A novel hybrid approach employing network-based fuzzy inference systems is introduced to propagate the model. Statistical analysis of system-wide data for each risk factor is performed to identify outliers and understand underlying distributions. They are then used to define fuzzy membership functions for model variables. Analytical Hierarch Process (AHP) is used to determine rules required by the model’s inference engine. Finally, the paper presents a prototype application of FRAT based on a subset of available domain data. © 2015 American Institute of Aeronautics and Astronautics Inc, AIAA. All right reserved.


Lyon R.E.,Aviation Research Division | Walters R.N.,Aviation Research Division
Journal of Hazardous Materials | Year: 2016

The energy released by failure of rechargeable 18-mm diameter by 65-mm long cylindrical (18650) lithium ion cells/batteries was measured in a bomb calorimeter for 4 different commercial cathode chemistries over the full range of charge using a method developed for this purpose. Thermal runaway was induced by electrical resistance (Joule) heating of the cell in the nitrogen-filled pressure vessel (bomb) to preclude combustion. The total energy released by cell failure, ΔHf, was assumed to be comprised of the stored electrical energy E (cell potential × charge) and the chemical energy of mixing, reaction and thermal decomposition of the cell components, ΔUrxn. The contribution of E and ΔUrxn to ΔHf was determined and the mass of volatile, combustible thermal decomposition products was measured in an effort to characterize the fire safety hazard of rechargeable lithium ion cells. © 2016


Wu Q.,Shanghai University of Electric Power | Wang P.,Shanghai University of Electric Power | Niu F.,Shanghai University of Electric Power | Huang C.,Aviation Research Division | And 2 more authors.
Applied Surface Science | Year: 2016

A small-pore silicon-substituted silicon aluminum phosphate (SAPO-34) molecular sieve, for the first time, is reported to significantly increase both the activity and life span of Ag3PO4 photocatalyst for visible-light degradation of methylene blue (MB) and rhodamine B (RhB). Results show that 60 wt.% Ag3PO4/SAPO-34 exhibits the highest photocatalytic degradation efficiencies for both MB (91.0% degradation within 2.0 min) and RhB (91.0% degradation within 7.0 min). In comparison, pure Ag3PO4 powder photocatalyst requires 8.0 min and 12.0 min for decomposing 91.0% of MB and RhB, respectively. During MB degradation the rate constant for 60 wt.% Ag3PO4/SAPO-34 increases 317.2% in comparison with the rate constant of pure Ag3PO4. This activity is also much higher than literature reported composite or supported Ag3PO4 photocatalysts. In three photocatalytic runs for the degradation of RhB, the rate constant for 60 wt.% Ag3PO4/SAPO-34 reduces from 0.33 to 0.18 min-1 (45.5% efficiency loss). In contrast, the rate constant of pure Ag3PO4 catalyst decreases from 0.2 to 0.07 min-1 (80.0% efficiency loss). All experimental results have shown that small pores and zero light absorption loss of SAPO-34 molecular sieves minimize Ag3PO4 loading, enhance photocatalytic activity and prolong the lifespan of Ag3PO4 photocatalyst. © 2016 Elsevier B.V. All rights reserved.


Campbell A.,Aviation Research Division | Cheng A.,Aviation Research Division
16th AIAA Aviation Technology, Integration, and Operations Conference | Year: 2016

Runway excursions, abnormal runway contact, and runway undershoot/overshoot are the third leading category of fatal commercial aviation accidents. One contributing factor is the lack of timely objective and accurate assessments of runway conditions. Feasible methods of using onboard aircraft data to achieve a timely reporting of the available runway friction have been sought to improve real-time assessment of runway conditions. Though the aircraft braking capability is an essential element for the runway condition assessement, it is not directly measured. Critical forces acting on the aircraft during the landing rollout must be properly measured or estimated to enable the airplane-based reporting approach. The uncertainty of each force calculation will determine the validity of such approach. In this study, we demonstrated a process to determine the uncertainty in the calculation of reverse thrust using in situ data. The analysis was performed on a reverser thrust model that uses a control volume analysis and engine station pressure and temperature ratios to calculate reverse thrust. The model was verified and validated using data collected by the FAA’s Global 5000 aircraft. A sensitivity analysis was performed using a response surface methodology to determine the most critical factors in the analysis. Then a Monte Carlo simulation was used to determine the uncertainty in the response. The analysis found that the uncertainty in the model input variables translates to an uncertainty of ±10% for the reverse thrust calculation. © 2016, American Institute of Aeronautics and Astronautics Inc, AIAA. All rights reserved.


Luo M.,Shanghai University of Electric Power | Yao W.,Shanghai University of Electric Power | Huang C.,Aviation Research Division | Wu Q.,Shanghai University of Electric Power | Xu Q.,Shanghai University of Electric Power
Journal of Materials Chemistry A | Year: 2015

The shape effects of Pt cocatalysts on the photocatalytic activity of Pt/CdS for hydrogen production were investigated for the first time. Nano-cubic and nano-spherical Pt particles were prepared via a shape-and-size-controlled technology and loaded onto a CdS semiconductor photocatalyst for visible light photocatalytic hydrogen production from an aqueous ammonium sulfite solution. Unlike conventional photodeposition and impregnation methods, shape-controlled synthesis is able to produce cubic Pt cocatalysts with tunable sizes. Pt nanocube loaded Pt/CdS photocatalysts show strong shape enhanced photocatalytic activity compared to those of Pt nanospherical particle loaded Pt/CdS photocatalysts. With the same Pt loading and Pt particle size the efficiencies of Pt nanocube loaded Pt/CdS catalysts are 52% and 31% higher than those of Pt nanosphere loaded Pt/CdS photocatalysts at 5.7 nm and 4.0 nm, respectively. In comparison with Pt/CdS photocatalysts prepared via photodeposition, more than 25% efficiency improvement has been achieved with the Pt nanocube loaded Pt/CdS photocatalysts. The electrochemical characterization of Pt nanoparticles revealed that photocatalytic activities of Pt/CdS photocatalysts rely on both the shape and size of the Pt particles. The higher the electrocatalytic activity of the Pt nanoparticles, the higher the efficiency of photocatalytic hydrogen evolution. This journal is © The Royal Society of Chemistry.


Luo M.,Shanghai University of Electric Power | Hong Y.,Shanghai University of Electric Power | Yao W.,Shanghai University of Electric Power | Huang C.,Aviation Research Division | And 2 more authors.
Journal of Materials Chemistry A | Year: 2015

The synthesis of colloidal Pt and Pt alloy nanoparticles (NPs) requires surfactants and capping agents to inhibit the overgrowth and aggregation of NPs. These reagents are also needed in the shape control synthesis of NPs to vary crystal growth rates in selected directions. Polyvinylpyrrolidone (PVP) is one of the most common water soluble capping agents for use in the synthesis of colloidal particles. However, PVP strongly adsorbed onto the surface of nanoparticles is detrimental when the NPs are used as catalysts, because surface adsorbed PVP blocks the access of reactant molecules to the active sites of nanoparticles. In this paper, we report a facile NaBH4/tert-butylamine (TBA) treatment technology for the effective removal of PVP from the surface of colloidal Pt-Pd nanocubes (NCs). This method does not change the morphology of the NPs. After treatment, the catalytic activity of Pt-Pd NCs significantly improves due to greater particle surface areas available for catalytic reactions. This facile method will find extensive applications in the fields of fuel cells, water electrolysis and photocatalytic hydrogen production. © The Royal Society of Chemistry 2015.


Luo M.,Shanghai University of Electric Power | Yao W.,Shanghai University of Electric Power | Huang C.,Aviation Research Division | Wu Q.,Shanghai University of Electric Power | Xu Q.,Shanghai University of Electric Power
RSC Advances | Year: 2015

Pd nanocubes and nanooctahedrons were synthesized via shape-controlled technology and loaded onto a commercial CdS semiconductor photocatalyst for visible light photocatalytic hydrogen production via photooxidation of an aqueous ammonium sulfite solution. High resolution TEM analysis indicates that Pd nanooctahedrons (Pd NOTs) are enclosed by eight {111} facets, while synthesized Pd nanocubes (Pd NCs) are enclosed by six {100} crystal planes. The hydrogen evolution rate of Pd NC loaded CdS photocatalyst (Pd-NCs/CdS) is 1.38 times higher than that of Pd NOT loaded Pd-NOTs/CdS photocatalyst. The electrochemical characterization reveals that the higher photocatalytic activity of Pd-NCs/CdS is attributed to the higher electrochemical active surface area (ECSA) and the electrochemical activities of the Pd {100} crystal planes of Pd NCs. © The Royal Society of Chemistry 2015.


PubMed | Aviation Research Division
Type: | Journal: Journal of hazardous materials | Year: 2016

The energy released by failure of rechargeable 18-mm diameter by 65-mm long cylindrical (18650) lithium ion cells/batteries was measured in a bomb calorimeter for 4 different commercial cathode chemistries over the full range of charge using a method developed for this purpose. Thermal runaway was induced by electrical resistance (Joule) heating of the cell in the nitrogen-filled pressure vessel (bomb) to preclude combustion. The total energy released by cell failure, Hf, was assumed to be comprised of the stored electrical energy E (cell potentialcharge) and the chemical energy of mixing, reaction and thermal decomposition of the cell components, Urxn. The contribution of E and Urxn to Hf was determined and the mass of volatile, combustible thermal decomposition products was measured in an effort to characterize the fire safety hazard of rechargeable lithium ion cells.

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