A5059158664- Computational Fluid Dynamics and Aerodynamics
- Gas Dynamics and Kinetic Theory
- Optical Network Technologies
- Advanced Photonic Communication Systems
- Fluid Dynamics and Turbulent Flows
- Rocket and propulsion systems research
- Photonic Crystal and Fiber Optics
- Semiconductor Lasers and Optical Devices
- Photonic and Optical Devices
- Advanced Fiber Optic Sensors
- Advanced Fiber Laser Technologies
- Spacecraft and Cryogenic Technologies
- Advanced Optical Network Technologies
- Advanced Numerical Methods in Computational Mathematics
- Conducting polymers and applications
- Organic Electronics and Photovoltaics
- Maritime Transport Emissions and Efficiency
- Radiative Heat Transfer Studies
- Advanced Thermoelectric Materials and Devices
- Photorefractive and Nonlinear Optics
- Simulation Techniques and Applications
- Particle Dynamics in Fluid Flows
- Graphene research and applications
- Plasma and Flow Control in Aerodynamics
- Carbon Nanotubes in Composites
Langley Research Center
2008-2024
Corning (United States)
2012-2024
University of Cambridge
2020-2024
Youngstown State University
2020
Los Alamos National Laboratory
2014
Technology Service Corporation (United States)
1999
National Aeronautics and Space Administration
1996
Washington University in St. Louis
1994
Shell (United States)
1989
Westinghouse Electric (United States)
1982
Doped organic semiconductors are critical to emerging device applications, including thermoelectrics, bioelectronics, and neuromorphic computing devices. It is commonly assumed that low conductivities in these materials result primarily from charge trapping by the Coulomb potentials of dopant counterions. Here, we present a combined experimental theoretical study rebutting this belief. Using newly developed doping technique based on ion exchange, prepare highly doped films with several...
We demonstrate wavelength- and mode-division multiplexed transmission over a fiber re-circulating loop comprising 50-km of low-DMGD few-mode fiber, an optimized EDFA with reduced wavelength-dependent gain mode-dependent gain. characterize the channel matrix in terms its singular value spread, investigate long-term stability.
Abstract Conducting polymers are of interest for a broad range applications from bioelectronics to thermoelectrics. The factors that govern their complex charge transport physics include the structural disorder present in these highly doped polymer films and Coulombic interactions between electronic carriers dopant counterions. Previous studies have shown at low doping levels strongly trapped vicinity counterions, while high is not limited by trapping, which manifests itself conductivity...
Abstract Doping is a crucial strategy to enhance the performance of various organic electronic devices. However, in many cases, random distribution dopants conjugated polymers leads disruption polymer microstructure, severely constraining achievable Here, it shown that by ion‐exchange doping polythiophene‐based P[(3HT) 1‐x ‐stat‐(T) x ] ( = 0 (P1), 0.12 (P2), 0.24 (P3), and 0.36 (P4)), remarkably high electrical conductivity >400 S cm −1 power factor >16 µW m K −2 are achieved for...
A hollow-core photonic band-gap fiber with very high group birefringence is fabricated and characterized. Two independent methods, wavelength scanning direct measurement of differential delay (DGD), are used to obtain the beatlength birefringence. The illustrates a 0.025 at 1550 nm. dependence also analyzed.
One of the recurring problems facing energy control center dispatchers each day is how to operate system during periods high load pickup, such that there sufflcient generation follow while still maintaining reasonable reserve and/or regulation margin. This paper shows a technical solution this problem which can be achieved with very efficient use computer resources. The expressed as dynamic programming scheduling problem, and feasible, but suboptimal proposed, eliminates usual search space...
Abstract Conjugated polymers are promising materials for thermoelectric applications, however, at present few effective and well‐understood strategies exist to further advance their performance. Here a new model system is reported better understanding of the key factors governing properties: aligned, ribbon‐phase poly[2,5‐ bis (3‐dodecylthiophen‐2‐yl)thieno[3,2‐b]thiophene] (PBTTT) doped by ion‐exchange doping. Using range microstructural spectroscopic methods, effect controlled...
Transmission capacities of 34.9Tb/s over 6375 km based on Gaussian-like DP-64APSK and 33.3 Tb/s 6800 using DP-32QAM are demonstrated hybrid spans with quasi-single-mode fiber. Nonlinear compensation enables 8.3 b/s/Hz spectral efficiency.
Understanding the charge transport mechanisms in chirality-selected single-walled carbon nanotube (SWCNT) networks and influence of network parameters is essential for further advances their optoelectronic thermoelectric applications. Here, we report on density temperature-dependent field-effect mobility on-chip field-effect-modulated Seebeck coefficient measurements polymer-sorted monochiral small-diameter (6,5) (0.76 nm) mixed large-diameter SWCNT (1.17-1.55 (plasma torch nanotubes, RN)...
Can we successfully apply XP (Extreme Programming) in a scientific research context? A pilot project at the NASA Langley Research Center tested XPs applicability this context. Since cultural environment government center differs from customer-centric business view, eight of 12 practices seemed incompatible with existing culture. Despite initial awkwardness, authors determined that can function situations for which it appears to be ill suited.
An elliptical-core hole assisted single-polarization fiber was designed, fabricated, and characterized. Numerical modeling based on the vectorial Maxwell equation reveals dependence of bandwidth core delta air-hole size. Several fibers this design with their operating windows centered between 0.9 1.5 µm were successfully demonstrated. A correlation birefringence is qualitatively confirmed. as high 55 nm observed. These also show very extinction ratios 60 dB or higher at lengths much shorter...
Supercontinuum (SC) with a continuous spectrum from ~0.8-3 mum is generated in standard single-mode fiber followed by high-nonlinearity fiber. The SC pumped 2-ns laser diode (LD) pulses amplified multistage amplifier, and the two octave spanning continuum achieved optimizing two-stage process that separates pulse breakup soliton formation spectral broadening. We also demonstrate scalability of average power 27 mW to 5.3 W increasing repetition rate 5 kHz 1 MHz, while maintaining comparable...
We study long-haul Quasi-Single-mode (QSM) systems in which signals are transmitted the fundamental modes of a few-mode fiber (FMF) while keeping other system components such as amplifiers and receivers kept single-moded. The large-effective-area nature FMF improves nonlinear tolerance expense mode coupling along transmissions induces multi-path interference (MPI) needs to be compensated. analytically investigate 6-spatial-polarization QSM transmission presence MPI show that weak regime,...
Numerical simulation of the Reynolds-averaged Navier–Stokes (RANS) equations has become a critical tool for design aerospace vehicles. However, issues that affect grid convergence three dimensional RANS solutions are not completely understood, as documented in AIAA Drag Prediction Workshop series. Grid adaption methods have potential increasing automation and discretization error control to impact certification process. The realization CFD Vision 2030 Study includes automated management...
A novel design of single polarization fiber is presented. The structure the comprises an elliptical central air hole with depressed cladding surrounding core. Parameters that affect performance in terms location operating window and bandwidth are analyzed. analysis results identification a can yield as high 240 nm around 1550 nm.
Get PDF Email Share with Facebook Tweet This Post on reddit LinkedIn Add to CiteULike Mendeley BibSonomy Citation Copy Text F. Yaman, S. Zhang, Y. Huang, E. Ip, J. D. Downie, W. A. Wood, Zakharian, Mishra, Hurley, I. B. Djordjevic, M. Mateo, K. Nakamura, T. Inoue, Inada, and Ogata, "First Quasi-Single-Mode Transmission over Transoceanic Distance using Few-mode Fibers," in Optical Fiber Communication Conference Deadline Papers, OSA Technical Digest (online) (Optica Publishing Group, 2015),...
The transmission of a single fundamental mode in fiber with cutoff wavelength above the band is studied as means allowing larger effective area and reducing nonlinearity. reduction nonlinear impairments achieved at expense potential new linear impairment form multipath interference (MPI). We use power-coupled-mode formalism to analyze growth MPI, effects cable attributes on its magnitude required complexity digital signal processing combat MPI. Hybrid spans comprised partially...
Hall effect measurements in doped polymer semiconductors are widely reported, but difficult to interpret due screening of voltages by carriers undergoing incoherent transport. Here, we propose a refined analysis for such measurements, based on measuring the coefficient as function temperature, and modelling existing regime variable "deflectability" (i.e. how strongly they "feel" magnetic part Lorentz force). By linearly interpolating each carrier between extremes no deflection full...
We measure the modal gain and noise figure characteristics of a ring-doped few-mode erbium-doped fiber amplifier. obtained 1 dB higher in LP11 than LP01 at an average 12.5 per mode.
We demonstrate a frequency-converted green laser source simultaneously emitting three spectral lines with nearly equal intensity and ~ 0.5 nm separation, enabling factor of √3 reduction speckle contrast in pico-projector applications. The consists an external cavity 1060 diode pump dual-wavelength reflection provided by volume Bragg grating quasi-periodically poled MgO-doped lithium niobate waveguide engineered to phase-match multiple-wavelength frequency conversion. 62 mW output power 33%...
Abstract High contact resistance remains the primary obstacle that hinders further advancements of organic semiconductors (OSCs) in electronic circuits. While significant effort has been directed toward lowering energy barrier at OSC/metal interfaces, approaches reducing another major contributor to overall – bulk have limited minimizing thickness OSC films. However, out‐of‐plane conductivity OSCs, a critical aspect resistance, largely remained unaddressed. In this study, multi‐layered 2D...
A highly birefringent hollow-core photonic bandgap fiber is fabricated and characterized. The group birefringence found to be 0.025 at 1550 nm through wavelength scanning method direct measurement of differential delay.
The effect of a pressure gradient on the local heating disturbance rectangular cavities tested at hypersonic freestream conditions has been globally assessed using two-color phosphor thermography method. These experiments were conducted in Langley 31-Inch Mach 10 Tunnel and initiated support Space Shuttle Return-To-Flight Program. Two blunted-nose test surface geometries developed, including an expansion plate with nearly constant negative flat zero gradient. designs flow characterizations...
The Columbia accident on February 1, 2003 began an unprecedented level of effort within the hypersonic aerothermodynamic community to support Space Shuttle Program. During approximately six month time frame primary Accident Investigation Board activity, many technical disciplines were involved in a concerted reconstruct last moments and her crew, understand critical events that led loss. Significant contributions CAIB activity made by community(REF CAIB) understanding re-entry environments...