452 Matching Results

Search Results

Results: 1 - 24 next
open access

UPTAKE OF RADIONUCLIDE METALS BY SPME FIBERS

Description: The Federal Bureau of Investigation (FBI) Laboratory currently does not have on site facilities for handling radioactive evidentiary materials and there are no established FBI methods or procedures for decontaminating high explosive (HE) and fire debris (FD) evidence while maintaining evidentiary value. One experimental method for the isolation of HE and FD residue involves using solid phase microextraction or SPME fibers to remove residue of interest. Due to their high affinity for organics, S… more
Date: August 28, 2006
Creator: Duff, M; S Crump, S; Robert02 Ray, R; Keisha Martin, K & Donna Beals, D
Item Type: Refine your search to only Article
Partner: UNT Libraries Government Documents Department
open access

Development of Sensors Using Evanescent Wave Interactions in Sapphire Optical Fibers

Description: The development of tunable diode laser absorption sensors for measurements in industrial boilers, both through direct absorption and evanescent wave absorption have been performed in the work presented here. These sensors use both direct and indirect absorption through the use of evanescent interactions within a coal firing combustion environment. For the direct absorption sensor, wavelength modulation absorption spectroscopy with second-harmonic detection was implemented within a physical prob… more
Date: December 31, 2006
Creator: Renfro, Michael W. & Jordan, Eric H.
Item Type: Refine your search to only Report
Partner: UNT Libraries Government Documents Department
open access

The Effect of Excess Carbon on the Crystallographic, Microstructural, and Mechanical Properties of CVD Silicon Carbide Fibers

Description: Silicon carbide (SiC) fibers made by chemical vapor deposition (CVD) are of interest for organic, ceramic, and metal matrix composite materials due their high strength, high elastic modulus, and retention of mechanical properties at elevated processing and operating temperatures. The properties of SCS-6{trademark} silicon carbide fibers, which are made by a commercial process and consist largely of stoichiometric SiC, were compared with an experimental carbon-rich CVD SiC fiber, to which excess… more
Date: December 5, 2006
Creator: Marzik, J V; Croft, W J; Staples, R J & MoberlyChan, W J
Item Type: Refine your search to only Article
Partner: UNT Libraries Government Documents Department
open access

Quality control studies of wavelength shifting fibers for a scintillator-based tail-catcher muon-tracker linear collider prototype detector

Description: Detailed measurements of the wavelength shifting fiber response to a stable and reliable light source are presented. Details about materials, a double reference method, and measurement technique are included. The fibers studied were several hundred KURARAY, Y-11, multiclad, 1.2mm outer diameter wavelength shifting fibers each cut from a reel to about one meter length. The fibers were polished, mirrored, and the mirrors were UV epoxy protected. Each fiber passed quality control requirements befo… more
Date: May 1, 2006
Creator: Dyshkant, A.; Beznosko, D.; Blazey, G.; Rykalin, V.; Zutshi, V.; Fisk, E. et al.
Item Type: Refine your search to only Article
Partner: UNT Libraries Government Documents Department
open access

Experimental Work With Photonic Band Gap Fiber: Building A Laser Electron Accelerator

Description: In the laser acceleration project E-163 at the Stanford Linear Accelerator Center, work is being done toward building a traveling wave accelerator that uses as its accelerating structure a length of photonic band gap fiber. The small scale of the optical fiber allows radiation at optical wavelengths to be used to provide the necessary accelerating energy. Optical wavelength driving energy in a small structure yields higher accelerating fields. The existence of a speed-of-light accelerating mode… more
Date: September 29, 2006
Creator: Lincoln, Melissa; Ischebeck, Rasmus; Nobel, Robert & Siemann, Robert
Item Type: Refine your search to only Article
Partner: UNT Libraries Government Documents Department
open access

Optical Fiber Chemical Sensor with Sol-Gel Derived Refractive Material as Transducer for High Temperature Gas Sensing in Clean Coal Technology

Description: The chemistry of sol-gel derived silica and refractive metal oxide has been systematically studied. Sol-gel processes have been developed for preparing porous silica and semiconductor metal oxide materials. Micelle/reversed micelle techniques have been developed for preparing nanometer sized semiconductor metal oxides and noble metal particles. Techniques for doping metal ions, metal oxides and nanosized metal particles into porous sol-gel material have also been developed. Optical properties o… more
Date: December 31, 2006
Creator: Tao, Shiquan
Item Type: Refine your search to only Report
Partner: UNT Libraries Government Documents Department
open access

LLNL SMP Light Diffuser Fabrication and Preliminary Data

Description: We are developing a cylindrical light diffuser using shape memory polymer (SMP) whose diameter, length, stiffness, and diffusion profile can be tailored to suit a particular application. The cylindrical SMP diffuser is made by casting SMP around the end of a glass optical fiber using a teflon tube as the casting mold, and abrading the cured SMP surface to cause the light to leak radially outward. The inner diameter of the casting tube is slightly larger than the fiber diameter. A smaller teflon… more
Date: June 2, 2006
Creator: Small, W., IV
Item Type: Refine your search to only Report
Partner: UNT Libraries Government Documents Department
open access

High Altitude Aerial Natural Gas Leak Detection System

Description: The objective of this program was to develop and demonstrate a cost-effective and power-efficient advanced standoff sensing technology able to detect and quantify, from a high-altitude (> 10,000 ft) aircraft, natural gas leaking from a high-pressure pipeline. The advanced technology is based on an enhanced version of the Remote Methane Leak Detector (RMLD) platform developed previously by Physical Sciences Inc. (PSI). The RMLD combines a telecommunications-style diode laser, fiber-optic comp… more
Date: December 31, 2006
Creator: Wainner, Richard T.; Frish, Mickey B.; Green, B. David; Laderer, Matthew C.; Allen, Mark G. & Morency, Joseph R.
Item Type: Refine your search to only Report
Partner: UNT Libraries Government Documents Department
open access

PRODUCTION OF CARBON PRODUCTS USING A COAL EXTRACTION PROCESS

Description: The purpose of this DOE-funded effort is to develop technologies for carbon products from coal-derived feedstocks. Carbon products can include precursor materials such as solvent extracted carbon ore (SECO) and synthetic pitch (Synpitch). In addition, derived products include carbon composites, fibers, foams and others. Key milestones included producing hydrogenated coal in the Hydrotreating Facility for the first time. The facility is now operational, although digital controls have not yet bee… more
Date: February 23, 2006
Creator: Dadyburjor, Dady; Chen, Chong; Kennel, Elliot B.; Magean, Liviu; Stansberry, Peter G.; Stiller, Alfred H. et al.
Item Type: Refine your search to only Report
Partner: UNT Libraries Government Documents Department
open access

Multi-watt 589nm fiber laser source

Description: We have demonstrated 3.5W of 589nm light from a fiber laser using periodically poled stoichiometric Lithium Tantalate (PPSLT) as the frequency conversion crystal. The system employs 938nm and 1583nm fiber lasers, which were sum-frequency mixed in PPSLT to generate 589nm light. The 938nm fiber laser consists of a single frequency diode laser master oscillator (200mW), which was amplified in two stages to >15W using cladding pumped Nd{sup 3+} fiber amplifiers. The fiber amplifiers operate at 9… more
Date: January 19, 2006
Creator: Dawson, Jay W.; Drobshoff, Alex D.; Beach, Raymond J.; Messerly, Michael J.; Payne, Stephen A.; Brown, Aaron et al.
Item Type: Refine your search to only Article
Partner: UNT Libraries Government Documents Department
open access

Statistical characterization of dislocation ensembles

Description: We outline a method to study the spatial and orientation statistics of dynamical dislocation systems by modeling the dislocations as a stochastic fiber process. Statistical measures have been introduced for the density, velocity, and flux of dislocations, and the connection between these measures and the dislocation state and plastic distortion rate in the crystal is explained. A dislocation dynamics simulation model has been used to extract numerical data to study the evolution of these statis… more
Date: May 17, 2006
Creator: El-Azab, A.; Deng, J. & Tang, M.
Item Type: Refine your search to only Article
Partner: UNT Libraries Government Documents Department
open access

Fiber Laser Replacement for Short Pulse Ti:Sapphire Oscillators -- Scalable Mode Locking to Record Pulse Energies

Description: We have investigated fiber-based lasers that mode-lock via three nonlinear mechanisms: pulse evolution, bend loss, and tunneling. Experiments with nonlinear pulse evolution proved especially promising; we report here a fiber laser that produces 25 nJ, sub-200 fs pulses, an energy that is 60% higher than previous reports. Experiments with nonlinear bend loss were inconclusive; though bend-loss data show that the effect exits, we were not able to use the phenomenon to lock a laser. New models sug… more
Date: February 14, 2006
Creator: Dawson, J W; Messerly, M J & An, J
Item Type: Refine your search to only Report
Partner: UNT Libraries Government Documents Department
open access

High energy mode locked fiber oscillators for high contrast, high energy petawatt laser seed sources

Description: In a high-energy petawatt laser beam line the ASE pulse contrast is directly related to the total laser gain. Thus a more energetic input pulse will result in increased pulse contrast at the target. We have developed a mode-locked fiber laser with high quality pulses and energies exceeding 25nJ. We believe this 25nJ result is scalable to higher energies. This oscillator has no intra-cavity dispersion compensation, which yields an extremely simple, and elegant laser configuration. We will discus… more
Date: June 15, 2006
Creator: Dawson, J W; Messerly, M J; An, J; Kim, D & Barty, C J
Item Type: Refine your search to only Article
Partner: UNT Libraries Government Documents Department
open access

Noise performance of the D0 layer 0 silicon detector

Description: A new inner detector called Layer 0 has been added to the existing silicon detector for the DZero colliding beams experiment. This detector has an all carbon fiber support structure that employs thin copper clad Kapton sheets embedded in the surface of the carbon fiber structure to improve the grounding of the structure and a readout system that fully isolates the local detector ground from the rest of the detector. Initial measurements show efficiencies greater than 90% and 0.3 ADC count commo… more
Date: November 1, 2006
Creator: Johnson, M.
Item Type: Refine your search to only Article
Partner: UNT Libraries Government Documents Department
open access

Visualization of Fiber Structurein the Left and Right Ventricleof a Human Heart

Description: The human heart is composed of a helical network of musclefibers. Anisotropic least squares filtering followed by fiber trackingtechniques were applied to Diffusion Tensor Magnetic Resonance Imaging(DTMRI) data of the excised human heart. The fiber configuration wasvisualized by using thin tubes to increase 3-dimensional visualperception of the complex structure. All visualizations were performedusing the high-quality ray-tracing software POV-Ray. The fibers are shownwithin the left and right v… more
Date: July 12, 2006
Creator: Rohmer, Damien; Sitek, Arkadiusz & Gullberg, Grant T.
Item Type: Refine your search to only Report
Partner: UNT Libraries Government Documents Department
open access

Uncertainty Quantification of Composite Laminate Damage with the Generalized Information Theory

Description: This work presents a survey of five theories to assess the uncertainty of projectile impact induced damage on multi-layered carbon-epoxy composite plates. Because the types of uncertainty dealt with in this application are multiple (variability, ambiguity, and conflict) and because the data sets collected are sparse, characterizing the amount of delamination damage with probability theory alone is possible but incomplete. This motivates the exploration of methods contained within a broad Genera… more
Date: May 1, 2006
Creator: Lucero, J.; Hemez, F.; Ross, T.; K.Kline; J.Hundhausen & Tippetts, T.
Item Type: Refine your search to only Report
Partner: UNT Libraries Government Documents Department
open access

Development of A Continuous Process for Displacement Dewatering

Description: The subject of this contract was to investigate the viability of a new process for dewatering paper called displacement pressing. The term “displacement pressing” was coined in the 1980s by researchers to describe a paper dewatering process where air is blown through a sheet of paper while it is being pressed. It was shown at that time that the combination of air and low pressing force could dramatically increase both sheet bulk and sheet solids which in theory would translate into huge savings… more
Date: October 30, 2006
Creator: Beck, Dave
Item Type: Refine your search to only Report
Partner: UNT Libraries Government Documents Department
open access

Final report :LDRD project 84269 supramolecular structures of peptide-wrapped carbon nanotubes.

Description: Carbon nanotubes (CNT) are unique nanoscale building blocks for a variety of materials and applications, from nanocomposites, sensors and molecular electronics to drug and vaccine delivery. An important step towards realizing these applications is the ability to controllably self-assemble the nanotubes into larger structures. Recently, amphiphilic peptide helices have been shown to bind to carbon nanotubes and thus solubilize them in water. Furthermore, the peptides then facilitate the assembly… more
Date: January 1, 2006
Creator: Rempe, Susan L.; Frischknecht, Amalie Lucile & Martin, Marcus Gary
Item Type: Refine your search to only Report
Partner: UNT Libraries Government Documents Department
open access

High-Resolution Adaptive Optics Scanning Laser Ophthalmoscope with Dual Deformable Mirrors

Description: Adaptive optics scanning laser ophthalmoscope (AO SLO) has demonstrated superior optical quality of non-invasive view of the living retina, but with limited capability of aberration compensation. In this paper, we demonstrate that the use of dual deformable mirrors can effectively compensate large aberrations in the human retina. We used a bimorph mirror to correct large-stroke, low-order aberrations and a MEMS mirror to correct low-stroke, high-order aberration. The measured ocular RMS wavefro… more
Date: August 11, 2006
Creator: Chen, D. C.; Jones, S. M.; Silva, D. A. & Olivier, S. S.
Item Type: Refine your search to only Article
Partner: UNT Libraries Government Documents Department
open access

Ultrabroadband 50-130 THz pulses generated via phase-matcheddifference frequency mixing in LiIO3

Description: We report the generation of ultrabroadband pulses spanningthe 50-130 THz frequency range via phase-matched difference frequencymixing within the broad spectrum of sub-10 fs pulses in LiIO_3. Modelcalculations reproduce the octave-spanning spectra and predict few-cycleTHz pulse durations less than 20~;fs. The applicability of this scheme isdemonstrated with 9-fs pulses from a Ti:sapphire oscillator and with 7-fsamplified pulses from a hollow fiber compressor as pumpsources.
Date: October 10, 2006
Creator: Zentgraf, Thomas; Huber, Rupert; Nielsen, Nils C.; Chemla, DanielS. & Kaindl, Robert A.
Item Type: Refine your search to only Article
Partner: UNT Libraries Government Documents Department
open access

Compatibility of SiC and SiC Composites with Molten Lead

Description: The choice of structural material candidates to contain Lead at 1000 C are limited in number. Silicon carbide composites comprise one choice of possible containment materials. Short term screening studies (120 hours) were undertaken to study the behavior of Silicon Carbide, Silicon Nitride, elemental Silicon and various Silicon Carbide fiber composites focusing mainly on melt infiltrated composites. Isothermal experiments at 1000 C utilized graphite fixtures to contain the Lead and material spe… more
Date: March 7, 2006
Creator: Tunison, H.
Item Type: Refine your search to only Report
Partner: UNT Libraries Government Documents Department
Back to Top of Screen