242 Matching Results

Search Results

Advanced search parameters have been applied.

Accuracy evaluation of residual stress measurements

Description: The accuracy of residual stress measurement techniques is difficult to assess due to the lack of available reference standards. To satisfy the need for reference standards, two specimens were designed and developed to provide known stress magnitudes and distributions: one with a uniform stress distribution and one with a nonuniform linear stress distribution. A reusable, portable load fixture was developed for use with each of the two specimens. Extensive bench testing was performed to determine if the specimens provide desired known stress magnitudes and distributions and stability of the known stress with time. The testing indicated that the nonuniform linear specimen and load fixture provided the desired known stress magnitude and distribution but that modifications were required for the uniform stress specimen. A trial use of the specimens and load fixtures using hole drilling was successful.
Date: May 1, 1996
Creator: Yerman, J.A.; Kroenke, W.C. & Long, W.H.
Partner: UNT Libraries Government Documents Department

Lawrence Livermore National Laboratory Working Reference Material Production Pla

Description: This Lawrence Livermore National Laboratory (LLNL) Working Reference Material Production Plan was written for LLNL by the Los Alamos National Laboratory to address key elements of producing seven Pu-diatomaceous earth NDA Working Reference Materials (WRMS). These WRMS contain low burnup Pu ranging in mass from 0.1 grams to 68 grams. The composite Pu mass of the seven WRMS was designed to approximate the maximum TRU allowable loading of 200 grams Pu. This document serves two purposes: first, it defines all the operations required to meet the LLNL Statement of Work quality objectives, and second, it provides a record of the production and certification of the WRMS. Guidance provided in ASTM Standard Guide C1128-89 was used to ensure that this Plan addressed all the required elements for producing and certifying Working Reference Materials. The Production Plan was written to provide a general description of the processes, steps, files, quality control, and certification measures that were taken to produce the WRMS. The Plan identifies the files where detailed procedures, data, quality control, and certification documentation and forms are retained. The Production Plan is organized into three parts: a) an initial section describing the preparation and characterization of the Pu02 and diatomaceous earth materials, b) middle sections describing the loading, encapsulation, and measurement on the encapsulated WRMS, and c) final sections describing the calculations of the Pu, Am, and alpha activity for the WRMS and the uncertainties associated with these quantities.
Date: November 4, 1998
Creator: Wong, Amy; Thronas, Denise & Marshall, Robert
Partner: UNT Libraries Government Documents Department

Issues in Purchasing and Maintaining Intrinsic Standards

Description: Intrinsic standards are widely used in the metrology community because they realize the best level uncertainty for many metrology parameters. For some intrinsic standards, recommended practices have been developed to assist metrologists in the selection of equipment and the development of appropriate procedures in order to realize the intrinsic standard. As with the addition of any new standard, the metrology laboratory should consider the pros and cons relative to their needs before purchasing the standard so that the laboratory obtains the maximum benefit from setting up and maintaining these standards. While the specific issues that need to be addressed depend upon the specific intrinsic standard and the level of realization, general issues that should be considered include ensuring that the intrinsic standard is compatible with the laboratory environment, that the standard is compatible with the current and future workload, and whether additional support standards will be required in order to properly maintain the intrinsic standard. When intrinsic standards are used to realize the best level of uncertainty for a specific metrology parameter, they usually require critical and important maintenance activities. These activities can including training of staff in the system operation, as well as safety procedures; performing periodic characterization measurements to ensure proper system operation; carrying out periodic intercomparisons with similar intrinsic standards so that proper operation is demonstrated; and maintaining control or trend charts of system performance. This paper has summarized many of these important issues and therefore should be beneficial to any laboratory that is considering the purchase of an intrinsic standard.
Date: September 12, 2000
Creator: Pettit, Richard B.; Jaeger, Klaus & Ehrlich, Charles D.
Partner: UNT Libraries Government Documents Department

Method and Appartus for Calibrating a Linear Variable Differential Transformer

Description: A calibration apparatus for calibrating a linear variable differential transformer (LVDT) having an armature positioned in au LVDT armature orifice, and the armature able to move along an axis of movement. The calibration apparatus includes a heating mechanism with an internal chamber, a temperature measuring mechanism for measuring the temperature of the LVDT, a fixture mechanism with an internal chamber for at least partially accepting the LVDT and for securing the LVDT within the heating mechanism internal chamber, a moving mechanism for moving the armature, a position measurement mechanism for measuring the position of the armature, and an output voltage measurement mechanism. A method for calibrating an LVDT, including the steps of powering the LVDT; heating the LVDT to a desired temperature; measuring the position of the armature with respect to the armature orifice; and measuring the output voltage of the LVDT.
Date: January 18, 2005
Creator: Pokrywka, Robert J.
Partner: UNT Libraries Government Documents Department

Glass particles produced by laser ablation for ICP-MSmeasurements

Description: Pulsed laser ablation (266nm) was used to generate glass particles from two sets of standard reference materials using femtosecond (150fs) and nanosecond (4ns) laser pulses with identical fluences of 50 J cm{sup -2}. Scanning electron microscopy (SEM) images of the collected particles revealed that there are more and larger agglomerations of particles produced by nanosecond laser ablation. In contrast to the earlier findings for metal alloy samples, no correlation between the concentration of major elements and the median particle size was found. When the current data on glass were compared with the metal alloy data, there were clear differences in terms of particle size, crater depth, heat affected zone, and ICP-MS response. For example, glass particles were larger than metal alloy particles, the craters in glass were less deep than craters in metal alloys, and damage to the sample was less pronounced in glass compared to metal alloys samples. The femtosecond laser generated more intense ICP-MS signals compared to nanosecond laser ablation for both types of samples, although glass sample behavior was more similar between ns and fs-laser ablation than for metals alloys.
Date: June 1, 2007
Creator: Gonzalez, J.; Liu, C.; Wen, S.; Mao, X. & Russo, R.E.
Partner: UNT Libraries Government Documents Department

Case for an Improved Effective-Atomic-Number for the Electronic Baggage Scanning Program

Description: Z{sub eff}, a parameter representing an 'effective atomic number' for a material, plays an important role in the Electronic Baggage Scanning Program (EBSP) to detect threats in dual-energy computed tomography (CT) baggage-scanning systems. We believe that Z{sub eff}, as defined and used on this program, does not provide the accurate representation of a material's x-ray absorption properties that is needed by the EBSP. We present the case for a new method that defines an effective atomic number for compounds and mixtures, which we refer to as Z{sub e}. Unlike Z{sub eff}, Z{sub e} is tied by definition to the x-ray absorption properties of each specific material. Use of this alternative will provide a more accurate scale for calibrating Micro-CT and EDS systems against standard reference materials and will provide a more accurate physical characterization of the x-ray properties of materials evaluated on those systems. This document: (1) Describes the current usage of the Z{sub eff} parameter; (2) Details problems entailed in the use of the Z{sub eff} parameter; (3) Proposes a well-defined alternative - Z{sub e}; (4) Proposes and demonstrates an algorithm for optimally associating Z{sub e} with any specified compound or mixture; (5) Discusses issues that can impact the usefulness of an effective-Z model; and (6) Recommends that, in order that the chosen effective-Z parameter not materially impact the accuracy of data produced by the EBSP program, the use of Z{sub eff} be replaced by Z{sub e}.
Date: April 5, 2011
Creator: Smith, J A; Martz, H E & Kallman, J S
Partner: UNT Libraries Government Documents Department

Carbonyl Emissions from Gasoline and Diesel Motor Vehicles

Description: Carbonyls from gasoline powered light-duty vehicles (LDVs) and heavy-duty diesel powered vehicles (HDDVs) operated on chassis dynamometers were measured using an annular denuder-quartz filter-polyurethane foam sampler with O-(2,3,4,5,6-pentafluorobenzyl)hydroxylamine derivatization and chromatography-mass spectrometry analyses. Two internal standards were utilized based on carbonyl recovery, 4-fluorobenzaldehyde for<C8 carbonyls and 6-fluoro-4-chromanone for>_C8 compounds. Gas- and particle-phase emissions for 39 aliphatic and 20 aromatic carbonyls ranged from 0.1 ? 2000 ?g/L fuel for LDVs and 1.8 - 27000 mu g/L fuel for HDDVs. Gas-phase species accounted for 81-95percent of the total carbonyls from LDVs and 86-88percent from HDDVs. Particulate carbonyls emitted from a HDDV under realistic driving conditions were similar to concentrations measured in a diesel particulate matter (PM) standard reference material. Carbonyls accounted for 19percent of particulate organic carbon (POC) emissions from low-emission LDVs and 37percent of POC emissions from three-way catalyst equipped LDVs. This identifies carbonyls as one of the largest classes of compounds in LDV PM emissions. The carbonyl fraction of HDDV POC was lower, 3.3-3.9percent depending upon operational conditions. Partitioning analysis indicates the carbonyls had not achieved equilibrium between the gas- and particle-phase under the dilution factors of 126-584 used in the current study.
Date: December 1, 2007
Creator: Destaillats, Hugo; Jakober, Chris A.; Robert, Michael A.; Riddle, Sarah G.; Destaillats, Hugo; Charles, M. Judith et al.
Partner: UNT Libraries Government Documents Department

FY2008 Calibration Systems Final Report

Description: The Calibrations project has been exploring alternative technologies for calibration of passive sensors in the infrared (IR) spectral region. In particular, we have investigated using quantum cascade lasers (QCLs) because these devices offer several advantages over conventional blackbodies such as reductions in size and weight while providing a spectral source in the IR with high output power. These devices can provide a rapid, multi-level radiance scheme to fit any nonlinear behavior as well as a spectral calibration that includes the fore-optics, which is currently not available for on-board calibration systems.
Date: January 1, 2009
Creator: Cannon, Bret D.; Myers, Tanya L. & Broocks, Bryan T.
Partner: UNT Libraries Government Documents Department

Phase reference materials for photoacoustic spectroscopy

Description: Interest in the phase of photoacoustic signals has increased greatly since the advent of phase modulation in FTIR spectroscopy. The photoacoustic phase provides information on the depth of the light-absorbing species within a solid sample. A spectroscopist needs data from a phase-reference material for standardizing phase measurements and for correcting the instrumental effects on the observed phase. Unfortunately, there is no universally accepted phase-reference material. The authors have studied the photoacoustic-signal phase and magnitude behavior for several potential phase-reference materials as a function of experimental parameters, such as beam modulation frequency, sample position in the photoacoustic cell, and cell purge gas. Theoretically, an ideal surface-absorbing material would have a photoacoustic phase that trails the phase of the excitation light by 90{degree}. They have found no material with this behavior, although some come close under a limited range of conditions. The three samples were separately sealed in the photoacoustic detector and illuminated by a red LED that was modulated at selected frequencies. The phases of the samples vary rapidly at very low frequencies because of the response of the cell microphone. Above that range, all three are within 10{degree} of the ideal 90{degree}, but each varies linearly with frequency with a different slope. The behaviors of these and other samples will be discussed in detail.
Date: June 1, 1999
Creator: Jones, R.; Bajic, S. & McClelland, J.
Partner: UNT Libraries Government Documents Department

Calibration Facilities for NIF

Description: The calibration facilities will be dynamic and will change to meet the needs of experiments. Small sources, such as the Manson Source should be available to everyone at any time. Carrying out experiments at Omega is providing ample opportunity for practice in pre-shot preparation. Hopefully, the needs that are demonstrated in these experiments will assure the development of (or keep in service) facilities at each of the laboratories that will be essential for in-house preparation for experiments at NIF.
Date: June 15, 2000
Creator: Perry, T. S.
Partner: UNT Libraries Government Documents Department

1990 Fischer Standard study

Description: The purpose of this work is to develop a set of Titanium areal density standards for calibration and maintenance of the Fischer`s X-ray Fluorescence measurement system characterization curve program. The electron microprobe was calibrated for Titanium films on ceramic substrates using an existing set of laboratory standards (Quantity: 6 Range: 0.310 to 1.605). Fourteen source assemblies were measured and assigned values. These values are based on a mean calculation, of five separate readings, from best curve fit equations developed form the plot of the laboratory standards areal density (Source Measure) versus electron microprobe measurement (reading). The best fit equations were determined using the SAS General Linear Modeling (GLM) procedure. Four separate best fit equations were evaluated (Linear, Quadratic, Cubic and Exponential). Areal density values for the Fischer Standards appear here ordered by best fit equation based on maximum R{sup 2}.
Date: September 12, 1990
Creator: Roubik, G.J.
Partner: UNT Libraries Government Documents Department

Preparation of Pu{sup 239} sources

Description: The Separations Technology Laboratory has prepared four sources to be used for calibrating a waste assay system (Passive/Active Neutron Assay) in Building 724-8G (Burial Ground). The four sources contain 0.5, 0.1, 0.05, and 0.01 grams Pu{sup 239}, respectively. The sources were prepared using aliquots from a single solution provided by the Quality Control (QC) group of Laboratories Department. The solution contained weapons-grade plutonium dissolved in nitric acid. Final solution acidity was 3M. Coulometry had been used to obtain a total plutonium content per unit volume. The weight percent of the plutonium isotopes present was obtained via mass spectrometry.
Date: August 5, 1988
Creator: Holcomb, H. P.
Partner: UNT Libraries Government Documents Department

Laboratory robotics -- An automated tool for preparing ion chromatography calibration standards

Description: This paper describes the use of a laboratory robot as an automated tool for preparing multi-level calibration standards for On-Line Ion Chromatography (IC) Systems. The robot is designed for preparation of up to six levels of standards, with each level containing up to eleven ionic species in aqueous solution. The robot is required to add the standards` constituents as both a liquid and solid additions and to keep a record of exactly what goes into making up every standard. Utilizing a laboratory robot to prepare calibration standards provides significant benefits to the testing environment. These benefits include: accurate and precise calibration standards in individually capped containers with preparation traceability; automated and unattended multi-specie preparation for both anion and cation analytical channels; the ability to free up a test operator from a repetitive routine and re-apply those efforts to test operations; The robot uses a single channel IC to analyze each prepared standard for specie content and concentration. Those results are later used as a measure of quality control. System requirements and configurations, robotic operations, manpower requirements, analytical verification, accuracy and precision of prepared solutions, and robotic downtime are discussed in detail.
Date: April 1, 1995
Creator: Chadwick, J.L.
Partner: UNT Libraries Government Documents Department

Test system electronic reference signal injection

Description: A concept for a method of injecting reference signals into waveform monitoring systems which has negligible effect on measurement accuracy is presented. Equations are provided which allow a test system designer to tailor the injection design to meet specific requirements. Examples of typical use are included. The signal injection concept presented has been successfully employed at GE Neutron Devices. It has been incorporated in quality assurance test systems to provide a fiducial or time zero reference marker for time correlation of waveforms monitored by independent digital oscilloscopes. It has also been found to be useful for the injection of simulated product waveforms employed for automatic test system calibration and/or operational verification just prior to product testing.
Date: June 1, 1991
Creator: Roubik, J.C.
Partner: UNT Libraries Government Documents Department

Metrology measurement capabilities

Description: Since 1958, the AlliedSignal Federal Manufacturing and Technologies (FM and T) Metrology Department has developed measurement technology and calibration capability in four major areas of measurement: (1) mechanical; (2) environmental, gas, liquid; (3) electrical (D.C., A.C., RF/Microwave); and (4) optical and radiation. The capabilities developed include unique capabilities in many areas of measurement and engineering expertise to develop measurement techniques and resolve measurement problems in these major areas. A strong audit function has been developed to provide a means to evaluate the calibration programs of the suppliers and internal calibration organizations. This evaluation includes measurement audits and technical surveys. The requirements placed on metrology require traceability of measurements to the National Institute of Standards and Technology or to nationally recognized methods or natural phenomena. A description of Metrology capabilities, traceability flow charts, and the measurement uncertainty of each of the measurement capabilities is contained in the report.
Date: February 1, 1997
Creator: Shroyer, K.
Partner: UNT Libraries Government Documents Department

Data analysis for surface plate calibration

Description: A surface plate is used to establish a reference plane used for making precision dimensional measurements. Ideally, the surface should be perfectly flat. Since it is impossible to create a perfectly flat surface, surface plate are calibrated to determine how much they deviate from a perfectly flat surface. Once a surface plate is calibrated, the user can determine if the plate is flat enough for use in a particular application. The currently accepted method of data analysis for surface plate calibration, the Moody method, does not give optimum results because of the arbitrary way in which the reference plane is chosen. The exact solution, wherein the reference plane is located in the optimum position, has been worked out and is given in a step by step procedure along with all of the necessary equations. The amount of calculation involved in a typical example proved to be prohibitive even for a computer, so an alternate solution using a least squares criterion for locating the reference plane was developed. Results were comparable with those from Moody`s method with values being smaller or greater depending on the shape of the plate.
Date: August 1, 1997
Creator: Burton, R.N.
Partner: UNT Libraries Government Documents Department

NCSL National Measurement Interlaboratory Comparison Database requirements

Description: With the recent development of an International Comparisons Database which provides worldwide access to measurement comparison data between National Measurement Institutes, there is currently renewed interest in developing a database of comparisons for calibration laboratories within a country. For many years, the National Conference of Standards Laboratories (NCSL), through the Measurement Comparison Programs Committee, has sponsored Interlaboratory Comparisons in a variety of measurement areas. This paper will discuss the need for such a National database which catalogues and maintains Interlaboratory Comparisons data. The paper will also discuss future requirements in this area.
Date: April 20, 2000
Creator: WHEELER,JAMES C. & PETTIT,RICHARD B.
Partner: UNT Libraries Government Documents Department

Spatial Bias in Field-Estimated Unsaturated Hydraulic Properties

Description: Hydraulic property measurements often rely on non-linear inversion models whose errors vary between samples. In non-linear physical measurement systems, bias can be directly quantified and removed using calibration standards. In hydrologic systems, field calibration is often infeasible and bias must be quantified indirectly. We use a Monte Carlo error analysis to indirectly quantify spatial bias in the saturated hydraulic conductivity, K{sub s}, and the exponential relative permeability parameter, {alpha}, estimated using a tension infiltrometer. Two types of observation error are considered, along with one inversion-model error resulting from poor contact between the instrument and the medium. Estimates of spatial statistics, including the mean, variance, and variogram-model parameters, show significant bias across a parameter space representative of poorly- to well-sorted silty sand to very coarse sand. When only observation errors are present, spatial statistics for both parameters are best estimated in materials with high hydraulic conductivity, like very coarse sand. When simple contact errors are included, the nature of the bias changes dramatically. Spatial statistics are poorly estimated, even in highly conductive materials. Conditions that permit accurate estimation of the statistics for one of the parameters prevent accurate estimation for the other; accurate regions for the two parameters do not overlap in parameter space. False cross-correlation between estimated parameters is created because estimates of K{sub s} also depend on estimates of {alpha} and both parameters are estimated from the same data.
Date: December 21, 2000
Creator: HOLT,ROBERT M.; WILSON,JOHN L. & GLASS JR.,ROBERT J.
Partner: UNT Libraries Government Documents Department

Internet-Based Calibration of a Multifunction Calibrator

Description: A new way of providing calibration services is evolving which employs the Internet to expand present capabilities and make the calibration process more interactive. Sandia National Laboratories and the National Institute of Standards and Technology are collaborating to set up and demonstrate a remote calibration of multijunction calibrators using this Internet-based technique that is becoming known as e-calibration. This paper describes the measurement philosophy and the Internet resources that can provide real-time audio/video/data exchange, consultation and training, as well as web-accessible test procedures, software and calibration reports. The communication system utilizes commercial hardware and software that should be easy to integrate into most calibration laboratories.
Date: December 19, 2000
Creator: BUNTING BACA,LISA A.; DUDA JR.,LEONARD E.; WALKER,RUSSELL M.; OLDHAM,NILE & PARKER,MARK
Partner: UNT Libraries Government Documents Department

CALCULATING ACCURATE SHUFFLER COUNT RATES WITH APPLICATIONS

Description: Shufflers are used to assay uranium and other fissile elements in bulk and waste quantities. They normally require physical calibration standards to achieve the most-accurate results, but such standards are generally rare and expensive, so inappropriate standards are often used out of necessity. This paper reports on a new technique that has been developed to calculate accurate count rates, in effect simulating physical standards with rapid and inexpensive calculations. The technique has been benchmarked on existing oxide and metallic standards, used to study a variety of conditions for which standards do not exist, and applied to inventory items needing verification measurements even though appropriate physical standards do not exist.
Date: May 1, 2001
Creator: RINARD, P. M.
Partner: UNT Libraries Government Documents Department

Optical properties of glazing materials at normal incidence

Description: Measurements of spectral transmittance T and reflectance R at normal incidence continue to be the most common and accurate source of energy performance data for glazing materials. Prediction of these radiometric properties from more fundamental materials data is often confounded by the complexity and uncertainty of coating structures. Angle-dependent radiometric properties of coated glazing will probably be predicted from normal-incidence data rather than being measured at many angles. The general error level demonstrated in round-robin tests is on the order 1-2%; it is often necessary to achieve better levels of performance. Based on results obtained following the round-robin tests, it is expected that accuracy of better than 0.5% can be generally achieved. A new type of absolute standard reference is described and tested with promising results.
Date: October 1, 2001
Creator: Rubin, M. & Powles, R.
Partner: UNT Libraries Government Documents Department