Science.gov

Sample records for laser transformation hardening

  1. Laser Hardening Prediction Tool Based On a Solid State Transformations Numerical Model

    SciTech Connect

    Martinez, S.; Ukar, E.; Lamikiz, A.

    2011-01-17

    This paper presents a tool to predict hardening layer in selective laser hardening processes where laser beam heats the part locally while the bulk acts as a heat sink.The tool to predict accurately the temperature field in the workpiece is a numerical model that combines a three dimensional transient numerical solution for heating where is possible to introduce different laser sources. The thermal field was modeled using a kinetic model based on Johnson-Mehl-Avrami equation. Considering this equation, an experimental adjustment of transformation parameters was carried out to get the heating transformation diagrams (CHT). With the temperature field and CHT diagrams the model predicts the percentage of base material converted into austenite. These two parameters are used as first step to estimate the depth of hardened layer in the part.The model has been adjusted and validated with experimental data for DIN 1.2379, cold work tool steel typically used in mold and die making industry. This steel presents solid state diffusive transformations at relative low temperature. These transformations must be considered in order to get good accuracy of temperature field prediction during heating phase. For model validation, surface temperature measured by pyrometry, thermal field as well as the hardened layer obtained from metallographic study, were compared with the model data showing a good adjustment.

  2. Numerical-experimental analysis of the effect of surface oxidation on the laser transformation hardening of Cr-Mo steels

    NASA Astrophysics Data System (ADS)

    Cordovilla, Francisco; García-Beltrán, Ángel; Dominguez, Jesús; Sancho, Paula; Ocaña, José L.

    2015-12-01

    Laser surface hardening is a technology that enables important advantages to be obtained in comparison with conventional techniques in terms of accuracy of the heat affected zone and productivity. Nevertheless, the development of realistic and flexible models has to be fulfilled in order to control the effects of every set of process conditions. Despite many different models having been developed, very few of them deal with the increment of absorption related with the instantaneous value of the layer of oxide growth during the process in a non-protective atmosphere. This work analyzes the problem of oxide formation at the external surface using kinetic relations, whose parameters have been related with the process variables, considering non-equilibrium conditions. Then, the oxide thickness was associated with a value of absorption through an innovative formula that considers the path of the laser radiation in the interface oxide-base material. The thermal calculations obtained by this method have allowed phase changes to be predicted using Avrami law. Both thermal and metallurgical results for different process conditions have been compared with experimental data showing an excellent agreement.

  3. Laser hardening process simulation for mechanical parts

    NASA Astrophysics Data System (ADS)

    Tani, G.; Orazi, L.; Fortunato, A.; Campana, G.; Cuccolini, G.

    2007-02-01

    In this paper a numerical simulation of laser hardening process is presented. The Finite Difference Method (FDM) was used to solve the heat transfer and the carbon diffusion equations for a defined workpiece geometry. The model is able to predict the thermal cycle into the target material, the phase transformations and the resulting micro-structures according to the laser parameters, the workpiece dimensions and the physical properties of the workpiece. The effects of the overlapping tracks of the laser beam on the resulting micro-structures is also considered. The initial workpiece micro-structure is taken into account in the simulation by a digitized photomicrograph of the ferrite perlite distribution before the thermal cycle. Experimental tests were realized on a C43 plate and the good agreement between the theoretical and experimental results is shown.

  4. Laser Surface Hardening of AISI 1045 Steel

    NASA Astrophysics Data System (ADS)

    Li, Ruifeng; Jin, Yajuan; Li, Zhuguo; Qi, Kai

    2014-09-01

    The study investigates laser surface hardening in the AISI 1045 steel using two different types of industrial laser: a high-power diode laser (HPDL) and a CO2 laser, respectively. The effect of process parameters such as beam power, travel speed on structure, case depth, and microhardness was examined. In most cases, a heat-affected zone (HAZ) formed below the surface; a substantial increase in surface hardness was achieved. In addition, big differences were found between the hardened specimens after HPDL surface hardening and CO2 laser surface hardening. For HPDL, depths of the HAZ were almost equal in total HAZ o, without surface melting. For CO2 laser, the depths changed a lot in the HAZ, with surface melting in the center. To better understand the difference of laser hardening results when use these two types of laser, numerical (ANSYS) analysis of the heat conduction involved in the process was also studied. For HPDL method, a rectangular beam spot and uniform energy distribution across the spot were assumed, while for CO2 laser, a circular beam spot and Gaussian energy distribution were assumed. The results showed that the energy distribution variety altered the thermal cycles of the HAZ dramatically. The rectangular HPDL laser beam spot with uniform energy distribution is much more feasible for laser surface hardening.

  5. Diamond films for laser hardening

    NASA Technical Reports Server (NTRS)

    Albin, S.; Watkins, L.; Ravi, K.; Yokota, S.

    1989-01-01

    Laser-damage experiments were performed on free-standing polycrystalline diamond films prepared by plasma-enhanced CVD. The high laser-induced stress resistance found for this material makes it useful for thin-film coatings for laser optics. Results for diamond-coated silicon substrates demonstrate the enhanced damage threshold imparted by diamond thin-film coatings to materials susceptible to laser damage.

  6. Pulsed laser surface hardening of ferrous alloys.

    SciTech Connect

    Xu, Z.; Reed, C. B.; Leong, K. H.; Hunter, B. V.

    1999-09-30

    A high power pulsed Nd:YAG laser and special optics were used to produce surface hardening on 1045 steel and gray cast iron by varying the process parameters. Unlike CO{sub 2} lasers, where absorptive coatings are required, the higher absorptivity of ferrous alloys at the Nd:YAG laser wavelength eliminates the necessity of applying a coating before processing. Metallurgical analysis of the treated tracks showed that very fine and hard martensitic microstructure (1045 steel) or inhomogeneous martensite (gray cast iron) were obtained without surface melting, giving maximum hardness of HRC 61 and HRC 40 for 1045 steel and gray cast iron respectively. The corresponding maximum case depths for both alloys at the above hardness are 0.6 mm. Gray cast iron was more difficult to harden without surface melting because of its lower melting temperature and a significantly longer time-at-temperature required to diffuse carbon atoms from the graphite flakes into the austenite matrix during laser heating. The thermal distortion was characterized in term of flatness changes after surface hardening.

  7. Surface hardening of steel by laser and electron beam. (Latest citations from Metadex). Published Search

    SciTech Connect

    1996-08-01

    The bibliography contains citations concerning electron beam hardening of steels and alloys. Among the materials surface hardened are carbon and alloy steels, aircraft spur gears, nitrocarburized steel, turbine blades, titanium-carbon steel, titanium, and rolling bearings. Effect of transformation plasticity on residual stress fields in laser surface hardening treatment is also examined.(Contains 50-250 citations and includes a subject term index and title list.) (Copyright NERAC, Inc. 1995)

  8. Surface hardening of steel by laser and electron beam. (Latest citations from METADEX). Published Search

    SciTech Connect

    Not Available

    1994-09-01

    The bibliography contains citations concerning electron beam hardening of steels and alloys. Among the materials surface hardened are carbon and alloy steels, aircraft spur gears, nitrocarburized steel, turbine blades, titanium-carbon steel, titanium, and rolling bearings. Effect of transformation plasticity on residual stress fields in laser surface hardening treatment is also examined. (Contains a minimum of 93 citations and includes a subject term index and title list.)

  9. Laser hardening techniques on steam turbine blade and application

    NASA Astrophysics Data System (ADS)

    Yao, Jianhua; Zhang, Qunli; Kong, Fanzhi; Ding, Qingming

    Different laser surface hardening techniques, such as laser alloying and laser solution strengthening were adopted to perform modification treatment on the local region of inset edge for 2Cr13 and 17-4PH steam turbine blades to prolong the life of the blades. The microstructures, microhardness and anti-cavitation properties were investigated on the blades after laser treatment. The hardening mechanism and technique adaptability were researched. Large scale installation practices confirmed that the laser surface modification techniques are safe and reliable, which can improve the properties of blades greatly with advantages of high automation, high quality, little distortion and simple procedure.

  10. SEU-hardened storage cell validation using a pulsed laser

    SciTech Connect

    Velazco, R.

    1996-12-01

    Laser tests performed on a prototype chip to validate new SEU-hardened storage cell designs revealed unexpected latch-up and single-event upset phenomena. The investigations that identified their location show the existence of a topology-dependent dual node upset mechanism. Design solutions are suggested to avoid its occurrence.

  11. Hardening of smooth pulsed laser deposited PMMA films by heating

    NASA Astrophysics Data System (ADS)

    Fuchs, Britta; Schlenkrich, Felix; Seyffarth, Susanne; Meschede, Andreas; Rotzoll, Robert; Vana, Philipp; Großmann, Peter; Mann, Klaus; Krebs, Hans-Ulrich

    2010-03-01

    Smooth poly(methyl methacrylate) (PMMA) films without any droplets were pulsed laser deposited at a wavelength of 248 nm and a laser fluence of 125 mJ/cm2. After deposition at room temperature, the films possess low universal hardness of only 3 N/mm2. Thermal treatments up to 200°C, either during deposition or afterwards, lead to film hardening up to values of 200 N/mm2. Using a combination of complementary methods, two main mechanisms could be made responsible for this temperature induced hardening effect well above the glass transition temperature of 102°C. The first process is induced by the evaporation of chain fragments and low molecular mass material, which are present in the film due to the ablation process, leading to an increase of the average molecular mass and thus to hardening. The second mechanism can be seen in partial cross-linking of the polymer film as soon as chain scission occurs at higher temperatures and the mobility and reactivity of the polymer material is high enough.

  12. The Effect of Hardenability Variation on Phase Transformation of Spiral Bevel Gear in Quenching Process

    NASA Astrophysics Data System (ADS)

    Zhang, Yingtao; Shi, Wankai; Yang, Lin; Gu, Zhifei; Li, Zhichao

    2016-05-01

    The hardenability of gear steel is dependent on the composition of alloying elements and is one of important criteria to assess process of phase transformation. The variation of hardenability has to be considered in control of the microstructures and distortion during gear quenching. In this paper, the quantitative effect of hardenability has been investigated on phase transformations of spiral bevel gears in die quenching. The hardenability deviation of 22CrMoH steel was assessed by using Jominy test. The dilatometry experiments were conducted to build phase transformation kinetic models for steels with low and high hardenability, respectively. The complete die quenching process of spiral bevel gear was modeled to reveal the significant difference on microstructures and temperature history with variation of hardenability. The final microstructures of the gear are martensite in surface layer after quenching process. There are bainite inside the gear tooth and the mixture of bainite and ferrite inside gear for the gear with low hardenability. The microstructure is bainite inside the gear with high hardenability.

  13. The Effect of Hardenability Variation on Phase Transformation of Spiral Bevel Gear in Quenching Process

    NASA Astrophysics Data System (ADS)

    Zhang, Yingtao; Shi, Wankai; Yang, Lin; Gu, Zhifei; Li, Zhichao

    2016-07-01

    The hardenability of gear steel is dependent on the composition of alloying elements and is one of important criteria to assess process of phase transformation. The variation of hardenability has to be considered in control of the microstructures and distortion during gear quenching. In this paper, the quantitative effect of hardenability has been investigated on phase transformations of spiral bevel gears in die quenching. The hardenability deviation of 22CrMoH steel was assessed by using Jominy test. The dilatometry experiments were conducted to build phase transformation kinetic models for steels with low and high hardenability, respectively. The complete die quenching process of spiral bevel gear was modeled to reveal the significant difference on microstructures and temperature history with variation of hardenability. The final microstructures of the gear are martensite in surface layer after quenching process. There are bainite inside the gear tooth and the mixture of bainite and ferrite inside gear for the gear with low hardenability. The microstructure is bainite inside the gear with high hardenability.

  14. Modelling of temperature evolution on metals during laser hardening process

    NASA Astrophysics Data System (ADS)

    Yánez, A.; Álvarez, J. C.; López, A. J.; Nicolás, G.; Pérez, J. A.; Ramil, A.; Saavedra, E.

    2002-01-01

    To achieve a precise and controlled laser process, an exhaustive analysis of the thermal behaviour of the material is necessary. In the present paper, a numerical simulation of the laser hardening process has been developed using both analytical solutions and the finite element code ANSYS™ to solve the heat transfer equation inside the treated material. The knowledge of the thermal cycles has enabled suitable processing parameters to be ascertained thus improving surface properties when metallic alloys have been irradiated. A simpler analytical method is also used to determine the mentioned parameters more quickly. This general purpose method has been applied to a specific experimental situation, namely the treatment of cylindrical pieces used in a multistage pump rotary jacket.

  15. Calculation of residual stresses induced during laser quench-hardening of steel

    SciTech Connect

    Shishkovskii, I.V.

    1992-06-01

    We present a theoretical and numerical analysis of the quasi-stationary uncoupled problem of thermoelastic-plasticity with the goal of estimating the amount of residual stress in steel after laser quench-hardening. 18 refs., 3 figs.

  16. Influence of laser hardening and resulting microstructure on fatigue properties of carbon steels

    SciTech Connect

    Cerny, I.; Fuerbacher, I.; Linhart, V.

    1998-06-01

    Cylindrical specimens of a CSN 12050 carbon steel, equivalent to the UNS G 10420 steel, with two different initial microstructures, normalized and heat treated, were surface processed without melting by a 2.5 kW, CO{sub 2} laser to study the effects of laser-beam hardening and resulting microstructure on fatigue properties and mechanisms. Two configurations of circumferential laser passes were made, resulting in one and three separate surface hardened lines, respectively. Fatigue resistance was studied using alternating bend tests. A detailed metallographic study and x-ray measurements of surface stresses were carried out. It was shown that the laser beam hardening under different conditions either reduced or slightly improved the fatigue life.

  17. Laser beam hardening of cast carbon steels, plain cast irons, and high-speed steels

    NASA Astrophysics Data System (ADS)

    Bylica, Andrzej; Adamiak, Stanislaw; Bochnowski, Wojciech; Dziedzic, Andrzej

    2000-11-01

    The examinations of the structure, hardness and abrasion resistance of surface layer of Fe-C alloys having the contents of carbon up to 4% and high-speed steel: 6-5-2, 4- 4-2-5+C after laser hardening are presented in the paper. They are compared with the properties obtained after conventional hardening. Laser of impulse operation - YAG:Nd and of continuous operation - CO2 were used. Analysis of structure was carried out based on metallographic and fractographic examinations as well as on X-ray properties, parameters of laser and conventional heat treatment of steels were defined.

  18. On the Precipitation Hardening of Selective Laser Melted AlSi10Mg

    NASA Astrophysics Data System (ADS)

    Aboulkhair, Nesma T.; Tuck, Chris; Ashcroft, Ian; Maskery, Ian; Everitt, Nicola M.

    2015-08-01

    Precipitation hardening of selective laser melted AlSi10Mg was investigated in terms of solution heat treatment and aging duration. The influence on the microstructure and hardness was established, as was the effect on the size and density of Si particles. Although the hardness changes according to the treatment duration, the maximum hardening effect falls short of the hardness of the as-built parts with their characteristic fine microstructure. This is due to the difference in strengthening mechanisms.

  19. Precipitation Reactions in Age-Hardenable Alloys During Laser Additive Manufacturing

    NASA Astrophysics Data System (ADS)

    Jägle, Eric A.; Sheng, Zhendong; Wu, Liang; Lu, Lin; Risse, Jeroen; Weisheit, Andreas; Raabe, Dierk

    2016-03-01

    We describe and study the thermal profiles experienced by various age-hardenable alloys during laser additive manufacturing (LAM), employing two different manufacturing techniques: selective laser melting and laser metal deposition. Using scanning electron microscopy and atom probe tomography, we reveal at which stages during the manufacturing process desired and undesired precipitation reactions can occur in age-hardenable alloys. Using examples from a maraging steel, a nickel-base superalloy and a scandium-containing aluminium alloy, we demonstrate that precipitation can already occur during the production of the powders used as starting material, during the deposition of material (i.e. during solidification and subsequent cooling), during the intrinsic heat treatment effected by LAM (i.e. in the heat affected zones) and, naturally, during an ageing post-heat treatment. These examples demonstrate the importance of understanding and controlling the thermal profile during the entire additive manufacturing cycle of age-hardenable materials including powder synthesis.

  20. Characteristics of laser beam welds of age-hardenable 6061-T6 aluminum alloy

    NASA Astrophysics Data System (ADS)

    Hirose, Akio; Kobayashi, Kojiro F.

    2003-03-01

    Laser beam welding is attractive for joining age-hardenable aluminum alloys, because its low over-all heat input results in a narrow weld heat affected zone (HAZ), where softening caused by dissolution of age precipitates occurs. In the present work, 1mm-thick 6061-T6 aluminum alloy plates were welded using a 2.5 kW CO2 laser and it was experimentally proved that the width of the softened region in the laser beam weld was less than 1/7 that of a TIG weld. Moreover the hardness in the softened region of the laser beam weld was found to be almost fully recovered to the base metal hardness by applying a post-weld aging treatment at 443 K for 28.8 ks without solution annealing unlike the TIG weld. These results characterize the advantage of laser beam welding in joining of the age-hardenable aluminum alloy as compared with the conventional arc welding. The hardness distributions in the HAZ were theoretically evaluated based on kinetic equations describing the dissolution of hardening β' (Mg2Si) precipitates and the precipitation of non-hardening β' (Mg2Si) precipitates during the weld thermal cycles to quantitatively prove above mentioned advantageous characteristics of laser beam welding.

  1. Pulse transformer for GaAs laser

    NASA Technical Reports Server (NTRS)

    Rutz, E. M.

    1976-01-01

    High-radiance gallium arsenide (GaAs) laser operating at room temperature is utilized in optical navigation system. For efficient transformer-to-laser impedance match, laser should be connected directly to pulse transformer secondary winding.

  2. Transient phonon vacuum squeezing due to femtosecond-laser-induced bond hardening

    NASA Astrophysics Data System (ADS)

    Cheenicode Kabeer, Fairoja; Grigoryan, Naira S.; Zijlstra, Eeuwe S.; Garcia, Martin E.

    2014-09-01

    Ultrashort optical pulses can be used both to create fundamental quasiparticles in crystals and to change their properties. In noble metals, femtosecond lasers induce bond hardening, but little is known about its origin and consequences. Here we simulate ultrafast laser excitation of silver at high fluences. We compute laser-excited potential-energy surfaces by all-electron ab initio theory and analyze the resulting quantum lattice dynamics. We also consider incoherent lattice heating due to electron-phonon interactions using the generalized two-temperature model. We find phonon hardening, which we attribute to the excitation of s electrons. We demonstrate that this may result in phonon vacuum squeezed states with an optimal squeezing factor of ˜0.001 at the L-point longitudinal mode. This finding implies that ultrafast laser-induced bond hardening may be used as a tool to manipulate the quantum state of opaque materials, where, so far, the squeezing of phonons below the zero-point motion has only been realized in transparent crystals by a different mechanism. On the basis of our finding, we further propose a method for directly measuring bond hardening.

  3. Fatigue Hardening Behavior of 1.5 GPa Grade Transformation-Induced Plasticity-Aided Martensitic Steel

    NASA Astrophysics Data System (ADS)

    Sugimoto, Koh-Ichi; Hojo, Tomohiko

    2016-04-01

    Low cycle fatigue hardening/softening behavior of a 0.2 pct C-1.5 pct Si-1.5 pct Mn-1.0 pct Cr-0.2 pct Mo-0.05 pct Nb transformation-induced plasticity (TRIP)-aided steel consisting of a wide lath martensite structure matrix and a narrow lath martensite-metastable retained austenite mixture was investigated. The steel exhibited notable fatigue hardening in the same way as TRIP-aided bainitic ferrite steel, although conventional martensitic steel such as SCM420 steel with the same tensile strength exhibited fatigue softening. The considerable fatigue hardening of this steel is believed to be associated mainly with the compressive internal stress that results from a difference in flow stress between the matrix and the martensite-austenite-like phase, with a small contribution from the strain-induced transformation and dislocation hardenings.

  4. Structural Relaxation and Nanocrystallization-Induced Laser Surface Hardening of Fe-Based Bulk Amorphous Alloys

    NASA Astrophysics Data System (ADS)

    Singh, Ashish K.; Alavi, S. Habib; Paital, Sameer R.; Dahotre, Narendra B.; Harimkar, Sandip P.

    2014-06-01

    Amorphous metallic alloys or bulk metallic glasses are emerging as promising materials for a range of structural, microelectromechanical systems, and biomedical applications. With the recent developments in spark plasma sintering and superplastic forming of the amorphous alloys, it is likely that the amorphous alloys will find a place in new applications. In this article, surface hardening of spark plasma sintered Fe48Cr15Mo14Y2C15B6 bulk amorphous alloys using a continuous-wave Nd:YAG laser is reported. Depending on the processing parameters, the laser surface irradiation causes structural relaxation (enhanced medium-range ordering and/or annihilation of excess free volume) and nanocrystallization of hard carbides (M23C6 and M7C3), resulting in surface hardening. Detailed investigations on the thermal effects, microstructural modifications, and hardness improvements due to laser surface irradiation with laser fluence in the range of 1.77-2.36 J/mm2 are presented. An increase in hardness in the range of 1360-1560 HV for laser surface-treated alloys compared to 1200 HV for as-sintered alloys over a hardening depth of about 50-80 µm is observed.

  5. High-power multibeam lasers and their applications for surface hardening

    NASA Astrophysics Data System (ADS)

    Bukhanova, I. F.; Divinsky, V. V.; Zhuravel, V. M.

    2000-07-01

    The paper deals with laser technological units (LTU) based on multi-beam lasers of 1 to 10 kW power. To save working gases the laser technological units employ regeneration systems. The LTU have been the basic units used in multipurpose systems for laser processing various parts of the kind of rotation bodies or plane parts, cranckshafts, etc., as well as in special-purpose systems and automatic lines with the full cycle of auxiliary technological operations which are necessary to perform laser processing. The technologies of heat treatment of parts with the use of multi-beam lasers have been developed for the purposes of improvement of heavy-loaded rubbing parts wear resistance; local treatment of non-rigid parts; reduction of labor consumption in some cases of thermo-chemical treatment or induction (bulk) hardening replacement with laser irradiation; reconditioning of worn parts by precision facing, alloying or similar processes.

  6. Protection performance evaluation regarding imaging sensors hardened against laser dazzling

    NASA Astrophysics Data System (ADS)

    Ritt, Gunnar; Körber, Michael; Forster, Daniel; Eberle, Bernd

    2014-10-01

    Electro-optical imaging sensors are widely distributed and used for many different tasks in military operations and civil security. However, their operational capability can be easily disturbed by laser radiation. The likeliness of such an incidence has dramatically increased in the past years due to the free availability of high-power laser pointers. These laser systems, offering laser powers of several watts, pose an increased risk to the human eye as well as to electro-optical sensors. An adequate protection of electro-optical sensors against dazzling is highly desirable. Such protection can be accomplished with different technologies; however, none of the existing technologies can provide a sufficient protection. All current protection measures possess individual advantages and disadvantages. We present the results on the performance of two different protection technologies. The evaluation is based on automatic optical pattern recognition of sensor images taken from a scene containing triangles.

  7. Pulsed-laser atom probe studies of a precipitation hardened maraging TRIP steel.

    PubMed

    Dmitrieva, O; Choi, P; Gerstl, S S A; Ponge, D; Raabe, D

    2011-05-01

    A precipitation hardened maraging TRIP steel was analyzed using a pulsed laser atom probe. The laser pulse energy was varied from 0.3 to 1.9 nJ to study its effect on the measured chemical compositions and spatial resolution. Compositional analyses using proximity histograms did not show any significant variations in the average matrix and precipitate compositions. The only remarkable change in the atom probe data was a decrease in the ++/+ charge state ratios of the elements. The values of the evaporation field used for the reconstructions exhibit a linear dependence on the laser pulse energy. The adjustment of the evaporation fields used in the reconstructions for different laser pulse energies was based on the correlation of the obtained cluster shapes to the TEM observations. No influence of laser pulse energy on chemical composition of the precipitates and on the chemical sharpness of their interfaces was detected. PMID:21215524

  8. EFFECT OF LASER LIGHT ON MATTER. LASER PLASMAS: Hardening of aluminium by YAG : Nd laser radiation with an average power of 0.8 kW

    NASA Astrophysics Data System (ADS)

    Kovsh, Ivan B.; Strekalova, M. S.

    1994-02-01

    An investigation is reported of the effects of a surface heat treatment of aluminium by a YAG : Nd laser beam with a power up to 0.8 kW. In particular, a study was made of the influence of the treatment conditions on the microhardness, as well as on the residual stresses and their sign in hardened surface layers of aluminium. The efficiency of aluminium hardening by radiation from a cw YAG : Nd laser was found to be considerably higher than in the case of a cw CO2 laser.

  9. Diagnostics hardening for harsh environment in Laser Megajoule (invited).

    PubMed

    Bourgade, J L; Marmoret, R; Darbon, S; Rosch, R; Troussel, P; Villette, B; Glebov, V; Shmayda, W T; Gomme, J C; Le Tonqueze, Y; Aubard, F; Baggio, J; Bazzoli, S; Bonneau, F; Boutin, J Y; Caillaud, T; Chollet, C; Combis, P; Disdier, L; Gazave, J; Girard, S; Gontier, D; Jaanimagi, P; Jacquet, H P; Jadaud, J P; Landoas, O; Legendre, J; Leray, J L; Maroni, R; Meyerhofer, D D; Miquel, J L; Marshall, F J; Masclet-Gobin, I; Pien, G; Raimbourg, J; Reverdin, C; Richard, A; Rubin de Cervens, D; Sangster, C T; Seaux, J P; Soullie, G; Stoeckl, C; Thfoin, I; Videau, L; Zuber, C

    2008-10-01

    The diagnostic designs for the Laser Megajoule (LMJ) will require components to operate in environments far more severe than those encountered in present facilities. This harsh environment will be induced by fluxes of neutrons, gamma rays, energetic ions, electromagnetic radiations, and, in some cases, debris and shrapnel, at levels several orders of magnitude higher than those experienced today on existing facilities. The lessons learned about the vulnerabilities of present diagnostic parts fielded mainly on OMEGA for many years, have been very useful guide for the design of future LMJ diagnostics. The present and future LMJ diagnostic designs including this vulnerability approach and their main mitigation techniques will be presented together with the main characteristics of the LMJ facility that provide for diagnostic protection. PMID:19044614

  10. Studies on Chip Control in Turning by Partially Laser Hardening of Carbon Steel

    NASA Astrophysics Data System (ADS)

    Lin, Yongchuan; Tanaka, Ryutaro; Hosokawa, Akira; Kusano, Takahiko; Ueda, Takashi

    This study deals with the chip control in turning by in-situ laser heat treatment of work material. Medium carbon steel JIS S45C is chosen as workpiece material because the ductile ferrite-pearlite structure of the base material can be relatively easily changed into the hard-brittle martensitic structure by laser heat. For the purpose of practical use, the direct diode laser (DDL) is selected because of its compact size, easiness of handling and high absorbance. Prior to turning process, the continuous-wave laser beam is irradiated on the workpiece surface in a longitudinal direction. This linear heat treatment makes it possible to break chips in turning every one revolution of workpiece at which the material is embrittled. The chip breakability depends mainly on the ratio of heat-treated depth to depth of cut. In spite that the workpiece is partially hardened, abnormal wear or chipping is not observed on the tool face after turning.

  11. Improved manufacturing techniques for RF and laser hardening of missile domes. Phase I. Technical report

    SciTech Connect

    Pawlewicz, W.T.; Mann, I.B.; Martin, P.M.; Hays, D.D.; Graybeal, A.G.

    1982-07-01

    This report summarizes key results and accomplishements during the first year of a Manufacturing Methods and Technology project to adapt an existing Pacific Northwest Laboratory (PNL) optical coating capability developed for high-power fusion-laser applications to the case of rf and laser hardening of plastic missile domes used by the US Army (MICOM). The primary objective of the first year's work was to demonstrate rf hardening of Hellfire and Copperhead 1.06-micron missile domes by use of transparent conductive Indium Tin Oxide (ITO) coatings. The project thus involved adaptation of a coating material and process developed for flat glass components used in fusion lasers to the case of hemispherical or conical heat-sensitive plastic domes used on laser-guided missiles. Specific ITO coating property goals were an electrical sheet resistance of 10 Ohms/square, a coated-dome transmission of 80% or more at 1.06 micron wavelength (compared to 90% for a bare dome), and good adhesion. The sheet resistance goal of 10 Ohms/square was expected to result in an rf attenuation of 30 dB at the frequencies of importance.

  12. Facilities to Support Beamed Energy Launch Testing at the Laser Hardened Materials Evaluation Laboratory (LHMEL)

    NASA Astrophysics Data System (ADS)

    Lander, Michael L.

    2003-05-01

    The Laser Hardened Materials Evaluation Laboratory (LHMEL) has been characterizing material responses to laser energy in support of national defense programs and the aerospace industry for the past 26 years. This paper reviews the overall resources available at LHMEL to support fundamental materials testing relating to impulse coupling measurement and to explore beamed energy launch concepts. Located at Wright-Patterson Air Force Base, Ohio, LHMEL is managed by the Air Force Research Laboratory Materials Directorate AFRL/MLPJ and operated by Anteon Corporation. The facility's advanced hardware is centered around carbon dioxide lasers producing output power up to 135kW and neodymium glass lasers producing up to 10 kilojoules of repetitively pulsed output. The specific capabilities of each laser device and related optical systems are discussed. Materials testing capabilities coupled with the laser systems are also described including laser output and test specimen response diagnostics. Environmental simulation capabilities including wind tunnels and large-volume vacuum chambers relevant to beamed energy propulsion are also discussed. This paper concludes with a summary of the procedures and methods by which the facility can be accessed.

  13. Unveiling the Origin of Work Hardening Behavior in an Ultrafine-Grained Manganese Transformation-Induced Plasticity Steel by Hydrogen Investigation

    NASA Astrophysics Data System (ADS)

    Zhu, Xu; Li, Wei; Zhao, Hongshan; Han, Qihang; Wang, Li; Jiao, Huisheng; Jin, Xuejun

    2016-09-01

    To reveal the origin of work hardening behavior in an ultrafine-grained manganese transformation-induced plasticity (TRIP) steel, specific experiments were designed with the assistance of hydrogen. Although the effect of hydrogen on the austenite transformation was negligible, the work hardening rate ( Θ) was apparently reduced for hydrogenated samples, indicating that TRIP effect cannot account for the high Θ alone. The collaborative effect of dislocation accumulation in ferrite and austenite transformation is proposed to explain the responsible mechanism.

  14. Unveiling the Origin of Work Hardening Behavior in an Ultrafine-Grained Manganese Transformation-Induced Plasticity Steel by Hydrogen Investigation

    NASA Astrophysics Data System (ADS)

    Zhu, Xu; Li, Wei; Zhao, Hongshan; Han, Qihang; Wang, Li; Jiao, Huisheng; Jin, Xuejun

    2016-07-01

    To reveal the origin of work hardening behavior in an ultrafine-grained manganese transformation-induced plasticity (TRIP) steel, specific experiments were designed with the assistance of hydrogen. Although the effect of hydrogen on the austenite transformation was negligible, the work hardening rate (Θ) was apparently reduced for hydrogenated samples, indicating that TRIP effect cannot account for the high Θ alone. The collaborative effect of dislocation accumulation in ferrite and austenite transformation is proposed to explain the responsible mechanism.

  15. An exhaustive model for the laser hardening of hypo eutectoid steel

    NASA Astrophysics Data System (ADS)

    Fortunato, Alessandro; Orazi, Leonardo; Cuccolini, Gabriele; Ascari, Alessandro

    2013-02-01

    This article presents an exhaustive mathematical model for the simulation of hypo-eutectoid carbon steel trans- formations during laser hardening. The proposed model takes into consideration all the the phenomena involved in the process with particular attention to implementing easy mathematical formulas in order to optimize the trade-o between the accuracy of the predicted results and the computational times. The proposed model calculates the 3D thermal eld occurring into the workpiece and predicts the microstructural evolution of the target material exploiting an original approach based on the de nition of thermodynamic thresholds. Several parameters and phenomena are taken into consideration in order to accurately simulate the process: laser beam characteristics, scanning strategy of the target and tempering e ect due to mutually interacting beam trajecto- ries.

  16. Impact toughness of a gradient hardened layer of Cr5Mo1V steel treated by laser shock peening

    NASA Astrophysics Data System (ADS)

    Xia, Weiguang; Li, Lei; Wei, Yanpeng; Zhao, Aimin; Guo, Yacong; Huang, Chenguang; Yin, Hongxiang; Zhang, Lingchen

    2015-09-01

    Laser shock peening (LSP) is a widely used surface treatment technique that can effectively improve the fatigue life and impact toughness of metal parts. Cr5Mo1V steel exhibits a gradient hardened layer after a LSP process. A new method is proposed to estimate the impact toughness that considers the changing mechanical properties in the gradient hardened layer. Assuming a linearly gradient distribution of impact toughness, the parameters controlling the impact toughness of the gradient hardened layer were given. The influences of laser power densities and the number of laser shots on the impact toughness were investigated. The impact toughness of the laser peened layer improves compared with an untreated specimen, and the impact toughness increases with the laser power densities and decreases with the number of laser shots. Through the fracture morphology analysis by a scanning electron microscope, we established that the Cr5Mo1V steel was fractured by the cleavage fracture mechanism combined with a few dimples. The increase in the impact toughness of the material after LSP is observed because of the decreased dimension and increased fraction of the cleavage fracture in the gradient hardened layer.

  17. Impact toughness of a gradient hardened layer of Cr5Mo1V steel treated by laser shock peening

    NASA Astrophysics Data System (ADS)

    Xia, Weiguang; Li, Lei; Wei, Yanpeng; Zhao, Aimin; Guo, Yacong; Huang, Chenguang; Yin, Hongxiang; Zhang, Lingchen

    2016-04-01

    Laser shock peening (LSP) is a widely used surface treatment technique that can effectively improve the fatigue life and impact toughness of metal parts. Cr5Mo1V steel exhibits a gradient hardened layer after a LSP process. A new method is proposed to estimate the impact toughness that considers the changing mechanical properties in the gradient hardened layer. Assuming a linearly gradient distribution of impact toughness, the parameters controlling the impact toughness of the gradient hardened layer were given. The influences of laser power densities and the number of laser shots on the impact toughness were investigated. The impact toughness of the laser peened layer improves compared with an untreated specimen, and the impact toughness increases with the laser power densities and decreases with the number of laser shots. Through the fracture morphology analysis by a scanning electron microscope, we established that the Cr5Mo1V steel was fractured by the cleavage fracture mechanism combined with a few dimples. The increase in the impact toughness of the material after LSP is observed because of the decreased dimension and increased fraction of the cleavage fracture in the gradient hardened layer.

  18. Formation quality optimization of laser hot wire cladding for repairing martensite precipitation hardening stainless steel

    NASA Astrophysics Data System (ADS)

    Wen, Peng; Feng, Zhenhua; Zheng, Shiqing

    2015-01-01

    Laser cladding is an advantaged repairing technology due to its low heat input and high flexibility. With preheating wire by resistance heat, laser hot wire cladding shows better process stability and higher deposition efficiency compared to laser cold wire/powder cladding. Multi-pass layer were cladded on the surface of martensite precipitation hardening stainless steel FV520B by fiber laser with ER410NiMo wire. Wire feed rate and preheat current were optimized to obtain stable wire transfer, which guaranteed good formation quality of single pass cladding. Response surface methodology (RSM) was used to optimize processing parameters and predict formation quality of multi-pass cladding. Laser power P, scanning speed Vs, wire feed rate Vf and overlap ratio η were selected as the input variables, while flatness ratio, dilution and incomplete fusion value as the responses. Optimal clad layer with flat surface, low dilution and no incomplete fusion was obtained by appropriately reducing Vf, and increasing P, Vs and η. No defect like pore or crack was found. The tensile strength and impact toughness of the clad layer is respectively 96% and 86% of those of the substrate. The clad layer showed nonuniform microstructure and was divided into quenched areas with coarse lath martensite and tempered areas with tempered martensite due to different thermal cycles in adjacent areas. The tempered areas showed similar hardness to the substrate.

  19. Microstructure and Mechanical Behavior of 17-4 Precipitation Hardenable Steel Processed by Selective Laser Melting

    NASA Astrophysics Data System (ADS)

    Rafi, H. Khalid; Pal, Deepankar; Patil, Nachiket; Starr, Thomas L.; Stucker, Brent E.

    2014-12-01

    The mechanical behavior and the microstructural evolution of 17-4 precipitation hardenable (PH) stainless steel processed using selective laser melting have been studied. Test coupons were produced from 17-4 PH stainless steel powder in argon and nitrogen atmospheres. Characterization studies were carried out using mechanical testing, optical microscopy, scanning electron microscopy, and x-ray diffraction. The results show that post-process heat treatment is required to obtain typically desired tensile properties. Columnar grains of smaller diameters (<2 µm) emerged within the melt pool with a mixture of martensite and retained austenite phases. It was found that the phase content of the samples is greatly influenced by the powder chemistry, processing environment, and grain diameter.

  20. Microstructure and Mechanical Behavior of 17-4 Precipitation Hardenable Steel Processed by Selective Laser Melting

    NASA Astrophysics Data System (ADS)

    Rafi, H. Khalid; Pal, Deepankar; Patil, Nachiket; Starr, Thomas L.; Stucker, Brent E.

    2014-09-01

    The mechanical behavior and the microstructural evolution of 17-4 precipitation hardenable (PH) stainless steel processed using selective laser melting have been studied. Test coupons were produced from 17-4 PH stainless steel powder in argon and nitrogen atmospheres. Characterization studies were carried out using mechanical testing, optical microscopy, scanning electron microscopy, and x-ray diffraction. The results show that post-process heat treatment is required to obtain typically desired tensile properties. Columnar grains of smaller diameters (<2 µm) emerged within the melt pool with a mixture of martensite and retained austenite phases. It was found that the phase content of the samples is greatly influenced by the powder chemistry, processing environment, and grain diameter.

  1. Prediction of Phase Transformation and Hardness Distribution of AISI 1045 Steel After Spot Continual Induction Hardening

    NASA Astrophysics Data System (ADS)

    Zhu, Shengxiao; Wang, Zhou; Qin, Xunpeng; Mao, Huajie; Gao, Kai

    2015-10-01

    An numerical and experimental study of spot continual induction hardening (SCIH) for AISI 1045 steel was carried out to gain a better understanding of this non-stationary and transverse flux induction hardening treatment. The SCIH device was set up by assembling the single-turn coil inductor to a five-axis cooperating computer numerical control system. The influence of inductor velocity, input current, and quenching medium on temperature field was estimated via the SCIH model, and the simulated micro-hardness and microstructure were validated by experimental verification. The heating delay phenomenon appearing in the SCIH process had been analyzed.

  2. Impact properties and hardening behavior of laser and electron-beam welds of V-4Cr-4Ti

    SciTech Connect

    Chung, H.M.; Strain, R.V.; Tsai, H.C.; Park, J.H.; Smith, D.L.

    1996-10-01

    The authors are conducting a program to develop an optimal laser welding procedure that can be applied to large-scale fusion-reactor structural components to be fabricated from vanadium-base alloys. Results of initial investigation of mechanical properties and hardening behavior of laser and electron-beam (EB) welds of the production-scale heat of V-4Cr-4Ti (500-kg Heat 832665) in as-welded and postwelding heat-treated (PWHT) conditions are presented in this paper. The laser weld was produced in air using a 6-kW continuous CO{sub 2} laser at a welding speed of {approx}45 mm/s. Microhardness of the laser welds was somewhat higher than that of the base metal, which was annealed at a nominal temperature of {approx}1050{degrees}C for 2 h in the factory. In spite of the moderate hardening, ductile-brittle transition temperatures (DBTTs) of the initial laser ({approx}80{degrees}C) and EB ({approx}30{degrees}C) welds were significantly higher than that of the base metal ({approx}{minus}170{degrees}C). However, excellent impact properties, with DBTT < {minus}80{degrees}C and similar to those of the base metal, could be restored in both the laser and EB welds by postwelding annealing at 1000{degrees}C for 1 h in vacuum.

  3. [Hardening of dental instruments].

    PubMed

    Gerasev, G P

    1981-01-01

    The possibility of prolonging the service life of stomatological instruments by the local hardening of their working parts is discussed. Such hardening should be achieved by using hard and wear-resistant materials. The examples of hardening dental elevators and hard-alloy dental drills are given. New trends in the local hardening of instruments are the treatment of their working parts with laser beams, the application of coating on their surface by the gas-detonation method. The results of research work and trials are presented. PMID:7300627

  4. Thermostructural Analysis of Carbon Cloth Phenolic Material Tested at the Laser Hardened Material Evaluation Laboratory

    NASA Technical Reports Server (NTRS)

    Clayton, J. Louie; Ehle, Curt; Saxon, Jeff (Technical Monitor)

    2002-01-01

    RSRM nozzle liner components have been analyzed and tested to explore the occurrence of anomalous material performance known as pocketing erosion. Primary physical factors that contribute to pocketing seem to include the geometric permeability, which governs pore pressure magnitudes and hence load, and carbon fiber high temperature tensile strength, which defines a material limiting capability. The study reports on the results of a coupled thermostructural finite element analysis of Carbon Cloth Phenolic (CCP) material tested at the Laser Hardened Material Evaluation Laboratory (the LHMEL facility). Modeled test configurations will be limited to the special case of where temperature gradients are oriented perpendicular to the composite material ply angle. Analyses were conducted using a transient, one-dimensional flow/thermal finite element code that models pore pressure and temperature distributions and in an explicitly coupled formulation, passes this information to a 2-dimensional finite element structural model for determination of the stress/deformation behavior of the orthotropic fiber/matrix CCP. Pore pressures are generated by thermal decomposition of the phenolic resin which evolve as a multi-component gas phase which is partially trapped in the porous microstructure of the composite. The nature of resultant pressures are described by using the Darcy relationships which have been modified to permit a multi-specie mass and momentum balance including water vapor condensation. Solution to the conjugate flow/thermal equations were performed using the SINDA code. Of particular importance to this problem was the implementation of a char and deformation state dependent (geometric) permeability as describing a first order interaction between the flow/thermal and structural models. Material property models are used to characterize the solid phase mechanical stiffness and failure. Structural calculations were performed using the ABAQUS code. Iterations were made

  5. Double Sided Irradiation for Laser-assisted Shearing of Ultra High Strength Steels with Process Integrated Hardening

    NASA Astrophysics Data System (ADS)

    Brecher, Christian; Emonts, Michael; Eckert, Markus; Weinbach, Matthias

    Most small or medium sized parts produced in mass production are made by shearing and forming of sheet metal. This technology is cost effective, but the achievable quality and geometrical complexity are limited when working high and highest strength steel. Based on the requirements for widening the process limits of conventional sheet metal working the Fraunhofer IPT has developed the laser-assisted sheet metal working technology. With this enhancement it is possible to produce parts made of high and highest strength steel with outstanding quality, high complexity and low tool wear. Additionally laser hardening has been implemented to adjust the mechanical properties of metal parts within the process. Currently the process is limited to lower sheet thicknesses (<2 mm) to maintain short cycle times. To enable this process for larger geometries and higher sheet thicknesses the Fraunhofer IPT developed a system for double sided laser-assisted sheet metal working within progressive dies.

  6. AISI/DOE Technology Roadmap Program: Development of Appropriate Resistance Spot Welding Practice for Transformation-Hardened Steels

    SciTech Connect

    Wayne Chuko; Jerry Gould

    2002-07-08

    This report describes work accomplished in the project, titled ''Development of Appropriate Resistance Spot Welding Practice for Transformation-Hardened Steels.'' The Phase 1 of the program involved development of in-situ temper diagrams for two gauges of representative dual-phase and martensitic grades of steels. The results showed that tempering is an effective way of reducing hold-time sensitivity (HTS) in hardenable high-strength sheet steels. In Phase 2, post-weld cooling rate techniques, incorporating tempering, were evaluated to reduce HTS for the same four steels. Three alternative methods, viz., post-heating, downsloping, and spike tempering, for HTS reduction were investigated. Downsloping was selected for detailed additional study, as it appeared to be the most promising of the cooling rate control methods. The downsloping maps for each of the candidate steels were used to locate the conditions necessary for the peak response. Three specific downslope conditions (at a fix ed final current for each material, timed for a zero-, medium-, and full-softening response) were chosen for further metallurgical and mechanical testing. Representative samples, were inspected metallographically, examining both local hardness variations and microstructures. The resulting downslope diagrams were found to consist largely of a C-curve. The softening observed in these curves, however, was not supported by subsequent metallography, which showed that all welds made, regardless of material and downslope condition, were essentially martensitic. CCT/TTT diagrams, generated based on microstructural modeling done at Oak Ridge National Laboratories, showed that minimum downslope times of 2 and 10 s for the martensitic and dual-phase grades of steels, respectively, were required to avoid martensite formation. These times, however, were beyond those examined in this study. These results show that downsloping is not an effective means of reducing HTS for production resistance spot

  7. Transverse intensity transformation by laser amplifiers

    NASA Astrophysics Data System (ADS)

    Litvin, Igor A.; King, Gary; Collett, Oliver J. P.; Strauss, Hencharl J.

    2015-03-01

    Lasers beams with a specific intensity profile such as super-Gaussian, Airy or Dougnut-like are desirable in many applications such as laser materials processing, medicine and communications. We propose a new technique for laser beam shaping by amplifying a beam in an end-pumped bulk amplifier that is pumped with a beam that has a modified intensity profile. Advantages of this method are that it is relatively easy to implement, has the ability to reshape multimode beams and is naturally suited to high power/energy beams. Both three and four level gain materials can be used as amplifier media. However, a big advantage of using three level materials is their ability to attenuate of the seed beam, which enhances the contrast of the shaping. We first developed a numerical method to obtain the required pump intensity for an arbitrary beam transformation. This method was subsequently experimentally verified using a three level system. The output of a 2.07 μm seed laser was amplified in a Ho:YLF bulk amplifier which was being pumped by a 1.89 μm Tm:YLF laser which had roughly a TEM10 Hermit Gaussian intensity profile. The seed beam was amplified from 0.3 W to 0.55 W at the full pump power of 35 W. More importantly, the beam profile in one transverse direction was significantly shaped from Gaussian to roughly flat-top, as the model predicted. The concept has therefore been shown to be viable and can be used to optimise the beam profile for a wide range of applications.

  8. Characterization of the thermal performance of high heat flux systems at the Laser Hardened Materials Evaluation Laboratory

    NASA Astrophysics Data System (ADS)

    Lander, Michael L.; Bagford, John O.; North, Mark T.; Hull, Robert J.

    1996-11-01

    When developing a high-heat-flux system, it is important to be able to test the system under relevant thermal conditions and environmental surroundings. Thermal characterization testing is best performed in parallel with analysis and design. This permits test results to impact materials selection and systems design decisions. This paper describes the thermal testing and characterization capabilities of the Laser Hardened Materials Evaluation Laboratory located at Wright-Patterson Air Force Base, Ohio. The facility features high-power carbon dioxide (CO2$ and neodymium:glass laser systems that can be teamed with vacuum chambers, wind tunnels, mechanical loading machines and/or ambient test sites to create application-specific thermal and environmental conditions local to the material sample or system. Representative results from recently conducted test series are summarized. The test series described demonstrate the successful use of a high power CO2 laser paired with environment simulation capability to : 1) simulate the expected in-service heat load on a newly developed heat transfer device to ensure its efficient operation prior to design completion, 2) simulate the heat load expected for a laser diode array cooler, 3) produce thermal conditions needed to test a radiator concept designed for space-based operation, and 4) produce thermal conditions experienced by materials use din solid rocket motor nozzles. Test diagnostics systems used to collect thermal and mechanical response data from the test samples are also described.

  9. IR laser-induced protein crystal transformation

    SciTech Connect

    Kiefersauer, Reiner Grandl, Brigitte; Krapp, Stephan; Huber, Robert

    2014-05-01

    A novel method and the associated instrumentation for improving crystalline order (higher resolution of X-ray diffraction and reduced mosaicity) of protein crystals by precisely controlled heating is demonstrated. Crystal transformation is optically controlled by a video system. A method and the design of instrumentation, and its preliminary practical realisation, including test experiments, with the object of inducing phase changes of biomolecular crystals by controlled dehydration through heating with infrared (IR) light are described. The aim is to generate and select crystalline phases through transformation in the solid state which have improved order (higher resolution in X-ray diffraction experiments) and reduced mosaic spread (more uniformly aligned mosaic blocks) for diffraction data collection and analysis. The crystal is heated by pulsed and/or constant IR laser irradiation. Loss of crystal water following heating and its reabsorption through equilibration with the environment is measured optically by a video system. Heating proved superior to traditional controlled dehydration by humidity change for the test cases CODH (carbon monoxide dehydrogenase) and CLK2 (a protein kinase). Heating with IR light is experimentally simple and offers an exploration of a much broader parameter space than the traditional method, as it allows the option of varying the rate of phase changes through modification of the IR pulse strength, width and repeat frequency. It impacts the crystal instantaneously, isotropically and homogeneously, and is therefore expected to cause less mechanical stress.

  10. Laser Cladding of CPM Tool Steels on Hardened H13 Hot-Work Steel for Low-Cost High-Performance Automotive Tooling

    NASA Astrophysics Data System (ADS)

    Chen, J.; Xue, L.

    2012-06-01

    This paper summarizes our research on laser cladding of high-vanadium CPM® tool steels (3V, 9V, and 15V) onto the surfaces of low-cost hardened H13 hot-work tool steel to substantially enhance resistance against abrasive wear. The results provide great potential for fabricating high-performance automotive tooling (including molds and dies) at affordable cost. The microstructure and hardness development of the laser-clad tool steels so obtained are presented as well.

  11. Microstructure and mechanical properties of hot wire laser clad layers for repairing precipitation hardening martensitic stainless steel

    NASA Astrophysics Data System (ADS)

    Wen, Peng; Cai, Zhipeng; Feng, Zhenhua; Wang, Gang

    2015-12-01

    Precipitation hardening martensitic stainless steel (PH-MSS) is widely used as load-bearing parts because of its excellent overall properties. It is economical and flexible to repair the failure parts instead of changing new ones. However, it is difficult to keep properties of repaired part as good as those of the substrate. With preheating wire by resistance heat, hot wire laser cladding owns both merits of low heat input and high deposition efficiency, thus is regarded as an advantaged repairing technology for damaged parts of high value. Multi-pass layers were cladded on the surface of FV520B by hot wire laser cladding. The microstructure and mechanical properties were compared and analyzed for the substrate and the clad layer. For the as-cladded layer, microstructure was found non-uniform and divided into quenched and tempered regions. Tensile strength was almost equivalent to that of the substrate, while ductility and impact toughness deteriorated much. With using laser scanning layer by layer during laser cladding, microstructure of the clad layers was tempered to fine martensite uniformly. The ductility and toughness of the clad layer were improved to be equivalent to those of the substrate, while the tensile strength was a little lower than that of the substrate. By adding TiC nanoparticles as well as laser scanning, the precipitation strengthening effect was improved and the structure was refined in the clad layer. The strength, ductility and toughness were all improved further. Finally, high quality clad layers were obtained with equivalent or even superior mechanical properties to the substrate, offering a valuable technique to repair PH-MSS.

  12. Practical aspects of systems hardening

    SciTech Connect

    Shepherd, W.J.

    1989-01-01

    Applications of hardening technology in a practical system require a balance between the factors governing affordability, producibility, and survivability of the finished design. Without careful consideration of the top-level system operating constraints, a design engineer may find himself with a survivable but overweight, unproductive, expensive design. This paper explores some lessons learned in applying hardening techniques to several laser communications programs and is intended as an introductory guide to novice designers faced with the task of hardening a space system.

  13. The Kinetics of Phase Transformations During Tempering in Laser Melted High Chromium Cast Steel

    NASA Astrophysics Data System (ADS)

    Li, M. Y.; Wang, Y.; Han, B.

    2012-06-01

    The precipitation of secondary carbides in the laser melted high chromium cast steels during tempering at 300-650 °C for 2 h in air furnace was characterized and the present phases was identified, by using transmission electron microscopy. Laser melted high chromium cast steel consists of austenitic dendrites and interdendritic M23C6 carbides. The austenite has such a strong tempering stability that it remains unchanged at temperature below 400 °C and the secondary hardening phenomenon starts from 450 °C to the maximum value of 672 HV at 560 °C. After tempering at 450 °C fine M23C6 carbides precipitate from the supersaturated austenite preferentially. In addition, the dislocation lines and slip bands still exist inside the austenite. While tempering at temperature below 560 °C, the secondary hardening simultaneously results from the martensite phase transformation and the precipitation of carbides as well as dislocation strengthening within a refined microstructure. Moreover, the formation of the ferrite matrix and large quality of coarse lamellar M3C carbides when the samples were tempered at 650 °C contributes to the decrease of hardness.

  14. IR laser-induced protein crystal transformation

    PubMed Central

    Kiefersauer, Reiner; Grandl, Brigitte; Krapp, Stephan; Huber, Robert

    2014-01-01

    A method and the design of instrumentation, and its preliminary practical realisation, including test experiments, with the object of inducing phase changes of biomolecular crystals by controlled dehydration through heating with infrared (IR) light are described. The aim is to generate and select crystalline phases through transformation in the solid state which have improved order (higher resolution in X-ray diffraction experiments) and reduced mosaic spread (more uniformly aligned mosaic blocks) for diffraction data collection and analysis. The crystal is heated by pulsed and/or constant IR laser irradiation. Loss of crystal water following heating and its reabsorption through equilibration with the environment is measured optically by a video system. Heating proved superior to traditional controlled dehydration by humidity change for the test cases CODH (carbon monoxide dehydrogenase) and CLK2 (a protein kinase). Heating with IR light is experimentally simple and offers an exploration of a much broader parameter space than the traditional method, as it allows the option of varying the rate of phase changes through modification of the IR pulse strength, width and repeat frequency. It impacts the crystal instantaneously, isotropically and homogeneously, and is therefore expected to cause less mechanical stress. PMID:24816092

  15. Explosive Surface Hardening of Austenitic Stainless Steel

    NASA Astrophysics Data System (ADS)

    Kovacs-Coskun, T.

    2016-04-01

    In this study, the effects of explosion hardening on the microstructure and the hardness of austenitic stainless steel have been studied. The optimum explosion hardening technology of austenitic stainless steel was researched. In case of the explosive hardening used new idea mean indirect hardening setup. Austenitic stainless steels have high plasticity and can be easily cold formed. However, during cold processing the hardening phenomena always occurs. Upon the explosion impact, the deformation mechanism indicates a plastic deformation and this deformation induces a phase transformation (martensite). The explosion hardening enhances the mechanical properties of the material, includes the wear resistance and hardness. In case of indirect hardening as function of the setup parameters specifically the flayer plate position the hardening increased differently. It was find a relationship between the explosion hardening setup and the hardening level.

  16. Laser surface pretreatment of 100Cr6 bearing steel - Hardening effects and white etching zones

    NASA Astrophysics Data System (ADS)

    Buling, Anna; Sändker, Hendrik; Stollenwerk, Jochen; Krupp, Ulrich; Hamann-Steinmeier, Angela

    2016-08-01

    In order to achieve a surface pretreatment of the bearing steel 100Cr6 (1-1.5 wt.% Cr) a laser-based process was used. The obtained modification may result in an optimization of the adhesive properties of the surface with respect to an anticorrosion polymer coating on the basis of PEEK (poly-ether-ether-ketone), which is applied on the steel surface by a laser melting technique. This work deals with the influence of the laser-based pretreatment regarding the surface microstructure and the micro-hardness of the steel, which has been examined by scanning electron microscopy (SEM), light microscopy and automated micro-hardness testing. The most suitable parameter set for the laser-based pretreatment leads to the formation of very hard white etching zones (WEZ) with a thickness of 23 μm, whereas this pretreatment also induces topographical changes. The occurrence of the white etching zones is attributed to near-surface re-austenitization and rapid quenching. Moreover, dark etching zones (DEZ) with a thickness of 32 μm are found at the laser path edges as well as underneath the white etching zones (WEZ). In these areas, the hardness is decreased due to the formation of oxides as a consequence of re-tempering.

  17. The African Laser Centre: Transforming the Laser Community in Africa

    NASA Astrophysics Data System (ADS)

    Mtingwa, Sekazi

    2012-02-01

    We describe the genesis and programs of the African Laser Centre (ALC), which is an African nonprofit network of laser users that is based in Pretoria, South Africa. Composed of over thirty laboratories from countries throughout the continent of Africa, the ALC has the mission of enhancing the application of lasers in research and education. Its programs include grants for research and training, equipment loans and donations, student scholarships, faculty grants for visits to collaborators' institutions, conferences, and technician training. A long-term goal of the ALC is to bring a synchrotron light source to Africa, most probably to South Africa. One highly popular program is the biennial conference series called the US-Africa Advanced Studies Institute, which is funded by the ALC in collaboration with the U.S. National Science Foundation and the International Center for Theoretical Physics in Trieste. The Institutes typically bring about thirty faculty and graduate students from the U.S. to venues in Africa in order to introduce U.S. and African graduate students to major breakthroughs in targeted areas that utilize lasers. In this presentation, we will summarize the ALC achievements to date and comment on the path forward.

  18. LASERS IN MEDICINE: Structure of matrices for the transformation of laser radiation by biofractals

    NASA Astrophysics Data System (ADS)

    Angel'skii, O. V.; Ushenko, A. G.; Arkhelyuk, A. D.; Ermolenko, S. B.; Burkovets, D. N.

    1999-12-01

    The changes in the state of polarisation of laser radiation transformed by biofractal objects are examined. The orientational angular structure of the matrix elements of the operator representing the optical properties of biofractals with different morphological structures (mineralised collagen fibres and myosin bundles) is investigated. An optical model for the description of fractal laser fields under the conditions of single light scattering is proposed.

  19. Hough Transform Based Corner Detection for Laser Beam Positioning

    SciTech Connect

    Awwal, A S

    2005-07-26

    In laser beam alignment in addition to detecting position, one must also determine the rotation of the beam. This is essential when a commissioning new laser beam for National Ignition Facility located at the Lawrence Livermore National Laboratory. When the beam is square, the positions of the corners with respect to one another provides an estimate of the rotation of the beam. This work demonstrates corner detection in the presence or absence of a second order non-uniform illumination caused by a spatial mask. The Hough transform coupled with illumination dependent pre-processing is used to determine the corner points. We show examples from simulated and real NIF images.

  20. Phase Transformation in Tantalum under Extreme Laser Deformation

    SciTech Connect

    Lu, C. -H.; Hahn, E. N.; Remington, B. A.; Maddox, B. R.; Bringa, E. M.; Meyers, M. A.

    2015-10-19

    The structural and mechanical response of metals is intimately connected to phase transformations. For instance, the product of a phase transformation (martensite) is responsible for the extraordinary range of strength and toughness of steel, making it a versatile and important structural material. Although abundant in metals and alloys, the discovery of new phase transformations is not currently a common event and often requires a mix of experimentation, predictive computations, and luck. High-energy pulsed lasers enable the exploration of extreme pressures and temperatures, where such discoveries may lie. The formation of a hexagonal (omega) phase was observed in recovered monocrystalline body-centered cubic tantalum of four crystallographic orientations subjected to an extreme regime of pressure, temperature, and strain-rate. This was accomplished using high-energy pulsed lasers. The omega phase and twinning were identified by transmission electron microscopy at 70 GPa (determined by a corresponding VISAR experiment). It is proposed that the shear stresses generated by the uniaxial strain state of shock compression play an essential role in the transformation. Lastly, molecular dynamics simulations show the transformation of small nodules from body-centered cubic to a hexagonal close-packed structure under the same stress state (pressure and shear).

  1. Phase Transformation in Tantalum under Extreme Laser Deformation.

    PubMed

    Lu, C-H; Hahn, E N; Remington, B A; Maddox, B R; Bringa, E M; Meyers, M A

    2015-01-01

    The structural and mechanical response of metals is intimately connected to phase transformations. For instance, the product of a phase transformation (martensite) is responsible for the extraordinary range of strength and toughness of steel, making it a versatile and important structural material. Although abundant in metals and alloys, the discovery of new phase transformations is not currently a common event and often requires a mix of experimentation, predictive computations, and luck. High-energy pulsed lasers enable the exploration of extreme pressures and temperatures, where such discoveries may lie. The formation of a hexagonal (omega) phase was observed in recovered monocrystalline body-centered cubic tantalum of four crystallographic orientations subjected to an extreme regime of pressure, temperature, and strain-rate. This was accomplished using high-energy pulsed lasers. The omega phase and twinning were identified by transmission electron microscopy at 70 GPa (determined by a corresponding VISAR experiment). It is proposed that the shear stresses generated by the uniaxial strain state of shock compression play an essential role in the transformation. Molecular dynamics simulations show the transformation of small nodules from body-centered cubic to a hexagonal close-packed structure under the same stress state (pressure and shear). PMID:26478106

  2. Phase transformation in tantalum under extreme laser deformation

    DOE PAGESBeta

    Lu, C. -H.; Hahn, E. N.; Remington, B. A.; Maddox, B. R.; Bringa, E. M.; Meyers, M. A.

    2015-10-19

    The structural and mechanical response of metals is intimately connected to phase transformations. For instance, the product of a phase transformation (martensite) is responsible for the extraordinary range of strength and toughness of steel, making it a versatile and important structural material. Although abundant in metals and alloys, the discovery of new phase transformations is not currently a common event and often requires a mix of experimentation, predictive computations, and luck. High-energy pulsed lasers enable the exploration of extreme pressures and temperatures, where such discoveries may lie. The formation of a hexagonal (omega) phase was observed in recovered monocrystalline body-centeredmore » cubic tantalum of four crystallographic orientations subjected to an extreme regime of pressure, temperature, and strain-rate. This was accomplished using high-energy pulsed lasers. The omega phase and twinning were identified by transmission electron microscopy at 70 GPa (determined by a corresponding VISAR experiment). It is proposed that the shear stresses generated by the uniaxial strain state of shock compression play an essential role in the transformation. In conclusion, molecular dynamics simulations show the transformation of small nodules from body-centered cubic to a hexagonal close-packed structure under the same stress state (pressure and shear).« less

  3. Phase transformation in tantalum under extreme laser deformation

    SciTech Connect

    Lu, C. -H.; Hahn, E. N.; Remington, B. A.; Maddox, B. R.; Bringa, E. M.; Meyers, M. A.

    2015-10-19

    The structural and mechanical response of metals is intimately connected to phase transformations. For instance, the product of a phase transformation (martensite) is responsible for the extraordinary range of strength and toughness of steel, making it a versatile and important structural material. Although abundant in metals and alloys, the discovery of new phase transformations is not currently a common event and often requires a mix of experimentation, predictive computations, and luck. High-energy pulsed lasers enable the exploration of extreme pressures and temperatures, where such discoveries may lie. The formation of a hexagonal (omega) phase was observed in recovered monocrystalline body-centered cubic tantalum of four crystallographic orientations subjected to an extreme regime of pressure, temperature, and strain-rate. This was accomplished using high-energy pulsed lasers. The omega phase and twinning were identified by transmission electron microscopy at 70 GPa (determined by a corresponding VISAR experiment). It is proposed that the shear stresses generated by the uniaxial strain state of shock compression play an essential role in the transformation. In conclusion, molecular dynamics simulations show the transformation of small nodules from body-centered cubic to a hexagonal close-packed structure under the same stress state (pressure and shear).

  4. Phase Transformation in Tantalum under Extreme Laser Deformation

    PubMed Central

    Lu, C.-H.; Hahn, E. N.; Remington, B. A.; Maddox, B. R.; Bringa, E. M.; Meyers, M. A.

    2015-01-01

    The structural and mechanical response of metals is intimately connected to phase transformations. For instance, the product of a phase transformation (martensite) is responsible for the extraordinary range of strength and toughness of steel, making it a versatile and important structural material. Although abundant in metals and alloys, the discovery of new phase transformations is not currently a common event and often requires a mix of experimentation, predictive computations, and luck. High-energy pulsed lasers enable the exploration of extreme pressures and temperatures, where such discoveries may lie. The formation of a hexagonal (omega) phase was observed in recovered monocrystalline body-centered cubic tantalum of four crystallographic orientations subjected to an extreme regime of pressure, temperature, and strain-rate. This was accomplished using high-energy pulsed lasers. The omega phase and twinning were identified by transmission electron microscopy at 70 GPa (determined by a corresponding VISAR experiment). It is proposed that the shear stresses generated by the uniaxial strain state of shock compression play an essential role in the transformation. Molecular dynamics simulations show the transformation of small nodules from body-centered cubic to a hexagonal close-packed structure under the same stress state (pressure and shear). PMID:26478106

  5. Phase Transformation in Tantalum under Extreme Laser Deformation

    DOE PAGESBeta

    Lu, C. -H.; Hahn, E. N.; Remington, B. A.; Maddox, B. R.; Bringa, E. M.; Meyers, M. A.

    2015-10-19

    The structural and mechanical response of metals is intimately connected to phase transformations. For instance, the product of a phase transformation (martensite) is responsible for the extraordinary range of strength and toughness of steel, making it a versatile and important structural material. Although abundant in metals and alloys, the discovery of new phase transformations is not currently a common event and often requires a mix of experimentation, predictive computations, and luck. High-energy pulsed lasers enable the exploration of extreme pressures and temperatures, where such discoveries may lie. The formation of a hexagonal (omega) phase was observed in recovered monocrystalline body-centeredmore » cubic tantalum of four crystallographic orientations subjected to an extreme regime of pressure, temperature, and strain-rate. This was accomplished using high-energy pulsed lasers. The omega phase and twinning were identified by transmission electron microscopy at 70 GPa (determined by a corresponding VISAR experiment). It is proposed that the shear stresses generated by the uniaxial strain state of shock compression play an essential role in the transformation. Lastly, molecular dynamics simulations show the transformation of small nodules from body-centered cubic to a hexagonal close-packed structure under the same stress state (pressure and shear).« less

  6. Laser induced structural transformation in chalcogenide based superlattices

    NASA Astrophysics Data System (ADS)

    Zallo, Eugenio; Wang, Ruining; Bragaglia, Valeria; Calarco, Raffaella

    2016-05-01

    Superlattices made of alternating layers of nominal GeTe and Sb2Te3 have been studied by micro-Raman spectroscopy. A structural irreversible transformation into ordered GeSbTe alloy is induced by high power laser light exposure. The intensity ratio of anti-Stokes and Stokes scattering under laser illumination gives a maximum average temperature in the sample of 177 °C. The latter is lower than the growth temperature and of 400 °C necessary by annealing to transform the structure in a GeSbTe alloy. The absence of this configuration after in situ annealing even up to 300 °C evidences an electronic excitation induced-transition which brings the system into a different and stable crystalline state.

  7. Fourier transform infrared spectroscopy (FTIR) of laser-irradiated cementum

    NASA Astrophysics Data System (ADS)

    Rechmann, Peter; White, Joel M.; Cecchini, Silvia C. M.; Hennig, Thomas

    2003-06-01

    Utilizing Fourier Transform Infrared Spectroscopy (FTIR) in specular reflectance mode chemical changes of root cement surfaces due to laser radiation were investigated. A total of 18 samples of root cement were analyzed, six served as controls. In this study laser energies were set to those known for removal of calculus or for disinfection of periodontal pockets. Major changes in organic as well as inorganic components of the cementum were observed following Nd:YAG laser irradiation (wavelength 1064 nm, pulse duration 250 μs, free running, pulse repetition rate 20 Hz, fiber diameter 320 μm, contact mode; Iskra Twinlight, Fontona, Slovenia). Er:YAG laser irradiation (wavelength 2.94 μm, pulse duration 250 μs, free running, pulse repetition rate 6 Hz, focus diameter 620 μm, air water cooling 30 ml/min; Iskra Twinlight, Fontona, Slovenia) significantly reduced the Amid bands due to changes in the organic components. After irradiation with a frequency doubled Alexandrite laser (wavelength 377 nm, pulse duration 200 ns, q-switched, pulse repetition rate 20 Hz, beam diameter 800 μm, contact mode, water cooling 30 ml/min; laboratory prototype) only minimal reductions in the peak intensity of the Amide-II band were detected.

  8. Helium-neon laser treatment transforms fibroblasts into myofibroblasts.

    PubMed Central

    Pourreau-Schneider, N.; Ahmed, A.; Soudry, M.; Jacquemier, J.; Kopp, F.; Franquin, J. C.; Martin, P. M.

    1990-01-01

    The differentiation of myofibroblastic cells from normal human gingival fibroblasts in vitro has been established by transmission electron microscopy and quantitated by immunohistochemistry, using antigelsolin monoclonal antibodies. Untreated control cultures were compared to cultures exposed to Helium-Neon (He-Ne) laser irradiation. A direct and massive transformation of the cultured fibroblasts into myofibroblasts was observed as early as 24 hours after laser treatment, whereas control cultures were comprised of only resting fibroblasts and active fibroblasts. This in vitro induction of myofibroblasts may be analogous to that which occurs in vivo. Therefore we undertook a similar study using biopsies from gingival tissues after wisdom tooth extraction. Myofibroblasts were present in the connective tissue of laser-treated gums 48 hours after irradiation, but not in untreated contralateral control tissues. These data provide evidence that the primary biologic effect of the Helium-Neon laser on connective tissue is the rapid generation of myofibroblasts from fibroblasts. The induction of a phenotype with contractile properties may have clinical significance in the acceleration of the wound-healing process. Images Figure 6 Figure 7 Figure 8 Figure 9 Figure 10 Figure 1 Figure 2 Figure 3 Figure 4 Figure 5 PMID:2372040

  9. Optimization of beam transformation system for laser-diode bars.

    PubMed

    Yu, Junhong; Guo, Linhui; Wu, Hualing; Wang, Zhao; Gao, Songxin; Wu, Deyong

    2016-08-22

    An optimized beam transformation system (BTS) is proposed to improve the beam quality of laser-diode bars. Through this optimized design, the deterioration of beam quality after the BTS can be significantly reduced. Both the simulation and experimental results demonstrate that the optimized system enables the beam quality of a mini-bar (9 emitters) approximately equal to 5.0 mm × 3.6 mrad in the fast-axis and slow-axis. After beam shaping by the optimized BTS, the laser-diode beam can be coupled into a 100 μm core, 0.15 numerical aperture (NA) fiber with an output power of over 100 W and an electric-optical efficiency of 46.8%. PMID:27557249

  10. Laser-diode-based joint transform correlator for fingerprint identification

    NASA Astrophysics Data System (ADS)

    Lal, Amit K.; Zang, De Yu; Millerd, James E.

    1999-01-01

    A laser-diode-based joint transform correlator (JTC) is reported here for the identification and discrimination of fingerprints. The system employs compact and inexpensive laser diodes as the light sources and a bacteriorhodopsin (BR) film in the Fourier plane, which can record the joint power spectrum without the need for expensive spatial light modulators or CCD cameras. The BR film also introduces nonlinearities in the Fourier plane which can improve JTC performance. In addition, real-time, all-optical programmable spatial filtering is demonstrated to improve the discrimination of the system. We present computer modeling and experimental results of this optical correlator, which shows excellent potential for the identification and discrimination of fingerprints.

  11. Gauge transformations in multichannel laser-interaction Hamiltonians

    NASA Astrophysics Data System (ADS)

    Armstrong, G. S. J.; Esry, B. D.

    2015-05-01

    In our previous studies of molecular photodissociation, we solved the time-dependent Schrödinger equation in full dimensionality, casting the laser-molecule interaction in a length-gauge form. The nuclear wave function is then expanded on a basis of symmetric top functions in the angular coordinates. However, a velocity gauge representation of the nuclear motion may be advantageous, and may reduce the number of partial waves required in the angular basis expansion. In molecular problems, the standard transformation between length and velocity gauge must take account of the presence of short-range non-linear radial dependence of the dipole. In problems involving a single channel, the short-range behavior is not removed by the gauge transformation, leading to a short-range mixed-gauge Hamiltonian. Having derived the form of this Hamiltonian, we extend our analysis to multichannel problems, where the gauge transformation is further complicated by off-diagonal dipole terms. We examine the impact of this transformation in full-dimensional calculations, particularly its effectiveness in reducing the required size of the angular basis. This work is supported by the Chemical Sciences, Geosciences, and Biosciences Division, Office of Basic Energy Sciences, Office of Science, U.S.A.

  12. Multipurpose hardened spacecraft insulation

    NASA Technical Reports Server (NTRS)

    Steimer, Carlos H.

    1990-01-01

    A Multipurpose Hardened Spacecraft Multilayer Insulation (MLI) system was developed and implemented to meet diverse survivability and performance requirements. Within the definition and confines of a MLI assembly (blanket), the design: (1) provides environmental protection from natural and induced nuclear, thermal, and electromagnetic radiation; (2) provides adequate electrostatic discharge protection for a geosynchronous satellite; (3) provides adequate shielding to meet radiated emission needs; and (4) will survive ascent differential pressure loads between enclosed volume and space. The MLI design is described which meets these requirements and design evolution and verification is discussed. The application is for MLI blankets which closeout the area between the laser crosslink subsystem (LCS) equipment and the DSP spacecraft cabin. Ancillary needs were implemented to ease installation at launch facility and to survive ascent acoustic and vibration loads. Directional venting accommodations were also incorporated to avoid contamination of LCS telescope, spacecraft sensors, and second surface mirrors (SSMs).

  13. Multiphoton time-delay spectroscopy using not transform-limited laser pulses

    NASA Astrophysics Data System (ADS)

    Cavalieri, Stefano; Materazzi, Marzia; Eramo, Roberto; Fini, Lorenzo; Giugni, Andrea

    2000-08-01

    We report on a two-photon resonant three-photon ionisation experiment performed on atomic barium with a sequence of two identical not transform-limited laser pulses in the weak field regime. We show that our results, obtained by a multimode nanosecond laser source, can be reproduced theoretically by using much shorter transform-limited pulses with the same spectral bandwidth.

  14. An investigation of phase transformation and crystallinity in laser surface modified H13 steel

    NASA Astrophysics Data System (ADS)

    Aqida, S. N.; Brabazon, D.; Naher, S.

    2013-03-01

    This paper presents a laser surface modification process of AISI H13 tool steel using 0.09, 0.2 and 0.4 mm size of laser spot with an aim to increase hardness properties. A Rofin DC-015 diffusion-cooled CO2 slab laser was used to process AISI H13 tool steel samples. Samples of 10 mm diameter were sectioned to 100 mm length in order to process a predefined circumferential area. The parameters selected for examination were laser peak power, overlap percentage and pulse repetition frequency (PRF). X-ray diffraction analysis (XRD) was conducted to measure crystallinity of the laser-modified surface. X-ray diffraction patterns of the samples were recorded using a Bruker D8 XRD system with Cu K α ( λ=1.5405 Å) radiation. The diffraction patterns were recorded in the 2 θ range of 20 to 80°. The hardness properties were tested at 981 mN force. The laser-modified surface exhibited reduced crystallinity compared to the un-processed samples. The presence of martensitic phase was detected in the samples processed using 0.4 mm spot size. Though there was reduced crystallinity, a high hardness was measured in the laser-modified surface. Hardness was increased more than 2.5 times compared to the as-received samples. These findings reveal the phase source of the hardening mechanism and grain composition in the laser-modified surface.

  15. Time resolved optical methods for investigation of phase transformations in materials exposed to nanosecond laser pulses

    NASA Astrophysics Data System (ADS)

    Martan, J.; Semmar, N.; Cibulka, O.

    2011-06-01

    Infrared (IR) radiometry and time resolved reflectivity (TRR) methods can be used for investigation of laser pulse effects on materials in nanosecond time scale. The methods in combination are capable to quantify object temperature and detect phase transformations in the solid state, melting and plasma formation from vapour. Measurements with different laser pulse energy densities provide threshold of the transformation. The melt duration can be also determined. The experimental system is described. It contains KrF excimer laser with homogenizer and variable attenuator, fast IR detector for radiometry, continuous probing laser with Si photodiode for reflectivity measurement and UV detector for pump laser pulse reflection measurement. The system was applied to investigation of responses to laser light of silicon and different pure metals and alloys. The range of energy densities used was 1-5500 mJ.cm-2 and measurements were done with temporal resolution of 6 ns for radiometry and 1 ns for reflectivity.

  16. Hardening of the arteries

    MedlinePlus

    Atherosclerosis; Arteriosclerosis; Plaque buildup - arteries; Hyperlipidemia - atherosclerosis; Cholesterol - atherosclerosis ... Hardening of the arteries often occurs with aging. As you grow older, ... narrows your arteries and makes them stiffer. These changes ...

  17. Detecting laser-range-finding signals in surveying converter lining based on wavelet transform

    NASA Astrophysics Data System (ADS)

    Li, Hongsheng; Yang, Xiaofei; Shi, Tielin; Yang, Shuzi

    1998-08-01

    The precision of the laser range finding subsystem has important influences on the performances of the whole measurement system applied to survey the steelmaking converter lining erosion state. In the system, the object of laser beams is some rough lighting surfaces in high temperature. the laser range finding signals to reach the microcomputer system would be submerged in intense disturb environments. Common laser range finding devices could not work normally. This paper presents a method based on the wavelet transform to test solving the problem. The idea of this method includes encoding the measuring signals, decomposing the encoded received signals of components in different frequency scales and time domains by the wavelet transform method, extracting the features of encoded signals according to queer points to confirm the arrival of signals, and accurately calculating out the measured distances. In addition, the method is also helpful to adopt some digital filter algorithms in time. It could make further in improvement on the precision.

  18. Diffractive optical elements for transformation of modes in lasers

    DOEpatents

    Sridharan, Arun K.; Pax, Paul H.; Heebner, John E.; Drachenberg, Derrek R.; Armstrong, James P.; Dawson, Jay W.

    2015-09-01

    Spatial mode conversion modules are described, with the capability of efficiently transforming a given optical beam profile, at one plane in space into another well-defined optical beam profile at a different plane in space, whose detailed spatial features and symmetry properties can, in general, differ significantly. The modules are comprised of passive, high-efficiency, low-loss diffractive optical elements, combined with Fourier transform optics. Design rules are described that employ phase retrieval techniques and associated algorithms to determine the necessary profiles of the diffractive optical components. System augmentations are described that utilize real-time adaptive optical techniques for enhanced performance as well as power scaling.

  19. Diffractive optical elements for transformation of modes in lasers

    DOEpatents

    Sridharan, Arun K; Pax, Paul H; Heebner, John E; Drachenberg, Derrek R.; Armstrong, James P.; Dawson, Jay W.

    2016-06-21

    Spatial mode conversion modules are described, with the capability of efficiently transforming a given optical beam profile, at one plane in space into another well-defined optical beam profile at a different plane in space, whose detailed spatial features and symmetry properties can, in general, differ significantly. The modules are comprised of passive, high-efficiency, low-loss diffractive optical elements, combined with Fourier transform optics. Design rules are described that employ phase retrieval techniques and associated algorithms to determine the necessary profiles of the diffractive optical components. System augmentations are described that utilize real-time adaptive optical techniques for enhanced performance as well as power scaling.

  20. SYNCHROTRON RADIATION, FREE ELECTRON LASER, APPLICATION OF NUCLEAR TECHNOLOGY, ETC.: X-ray beam hardening correction for measuring density in linear accelerator industrial computed tomography

    NASA Astrophysics Data System (ADS)

    Zhou, Ri-Feng; Wang, Jue; Chen, Wei-Min

    2009-07-01

    Due to X-ray attenuation being approximately proportional to material density, it is possible to measure the inner density through Industrial Computed Tomography (ICT) images accurately. In practice, however, a number of factors including the non-linear effects of beam hardening and diffuse scattered radiation complicate the quantitative measurement of density variations in materials. This paper is based on the linearization method of beam hardening correction, and uses polynomial fitting coefficient which is obtained by the curvature of iron polychromatic beam data to fit other materials. Through theoretical deduction, the paper proves that the density measure error is less than 2% if using pre-filters to make the spectrum of linear accelerator range mainly 0.3 MeV to 3 MeV. Experiment had been set up at an ICT system with a 9 MeV electron linear accelerator. The result is satisfactory. This technique makes the beam hardening correction easy and simple, and it is valuable for measuring the ICT density and making use of the CT images to recognize materials.

  1. Laser Mode Behavior of the Cassini CIRS Fourier Transform Spectrometer at Saturn

    NASA Technical Reports Server (NTRS)

    Brasunas, John C.

    2012-01-01

    The CIRS Fourier transform spectrometer aboard the NASA/ESA/ASI Cassini orbiter has been acquiring spectra of the Saturnian system since 2004. The CIRS reference interferometer employs a laser diode to trigger the interferogram sampling. Although the control of laser diode drive current and operating temperature are stringent enough to restrict laser wavelength variation to a small fraction of CIRS finest resolution element, the CIRS instrument does need to be restarted every year or two, at which time it may start in a new laser mode. By monitoring the Mylar absorption features in uncalibrated spectra due to the beam splitter Mylar substrate, it can be shown that these jumps are to adjacent modes and that most of the eight-year operation so far is restricted to three adjacent modes. For a given mode, the wavelength stability appears consistent with the stability of the laser diode drive curren.t and operating temperature.

  2. 42. INTERIOR VIEW OF THE NAIL HARDENER USED TO HARDEN ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    42. INTERIOR VIEW OF THE NAIL HARDENER USED TO HARDEN AND TEMPER THE NAILS; WEST TUBES IN FOREGRPUND AND DRAWBACK TUBE IN THE CENTER - LaBelle Iron Works, Thirtieth & Wood Streets, Wheeling, Ohio County, WV

  3. Semiconductor laser self-mixing micro-vibration measuring technology based on Hilbert transform

    NASA Astrophysics Data System (ADS)

    Tao, Yufeng; Wang, Ming; Xia, Wei

    2016-06-01

    A signal-processing synthesizing Wavelet transform and Hilbert transform is employed to measurement of uniform or non-uniform vibrations in self-mixing interferometer on semiconductor laser diode with quantum well. Background noise and fringe inclination are solved by decomposing effect, fringe counting is adopted to automatic determine decomposing level, a couple of exact quadrature signals are produced by Hilbert transform to extract vibration. The tempting potential of real-time measuring micro vibration with high accuracy and wide dynamic response bandwidth using proposed method is proven by both simulation and experiment. Advantages and error sources are presented as well. Main features of proposed semiconductor laser self-mixing interferometer are constant current supply, high resolution, simplest optical path and much higher tolerance to feedback level than existing self-mixing interferometers, which is competitive for non-contact vibration measurement.

  4. Manipulating mammalian cell by phase transformed titanium surface fabricated through ultra-short pulsed laser synthesis.

    PubMed

    Chinnakkannu Vijayakumar, Sivaprasad; Venkatakrishnan, Krishnan; Tan, Bo

    2016-01-15

    Developing cell sensitive indicators on interacting substrates that allows specific cell manipulation by a combination of physical, chemical or mechanical cues is a challenge for current biomaterials. Hence, various fabrication approaches have been created on a variety of substrates to mimic or create cell specific cues. However, to achieve cell specific cues a multistep process or a post-chemical treatment is often necessitated. So, a simple approach without any chemical or biological treatment would go a long way in developing bio-functionalized substrates to effectively modulate cell adhesion and interaction. The present investigation is aimed to study the manipulative activity induced by phase transformed titanium surface. An ultra-short laser is used to fabricate the phase transformed titanium surface where a polymorphic titanium oxide phases with titanium monoxide (TiO), tri-titanium oxide (Ti3O) and titanium dioxide (TiO2) have been synthesized on commercially pure titanium. Control over oxide phase transformed area was demonstrated via a combination of laser scanning time (laser pulse interaction time) and laser pulse widths (laser pulse to pulse separation time). The interaction of phase transformed titanium surface with NIH3T3 fibroblasts and MC3T3-E1 osteoblast cells developed a new bio-functionalized platforms on titanium based biomaterials to modulate cell migration and adhesion. The synthesized phase transformed titanium surface on the whole appeared to induce directional cues for cell migration with unique preferential cell adhesion unseen by other fabrication approaches. The precise bio-functionalization controllability exhibited during fabrication offers perceptible edge for developing a variety of smart bio-medical devices, implants and cardiovascular stents where the need in supressing specific cell adhesion and proliferation is of great demand. PMID:26546983

  5. Microstructure and phase transformations in laser clad CrxSy/Ni coating on H13 steel

    NASA Astrophysics Data System (ADS)

    Lei, Yiwen; Sun, Ronglu; Tang, Ying; Niu, Wei

    2015-03-01

    Laser cladding was carried out onto H13 steel with preplaced NiCrBSi+Ni/MoS2 powders using CO2 laser under the optimized experimental parameters of laser power 2 kW, scanning velocity 6 mm/s and laser beam diameter 3 mm. An X-ray diffractometer and scanning electron microscope with energy dispersive spectroscopy were applied to analyze the microstructure and phase compositions of the coating. Thermodynamic calculation was performed with Thermo-Calc software on the basis of a commercially available Ni-based Alloys' database. The experimental results show that MoS2 decomposed and S reacted with Cr to form nonstoichiometric CrxSy during the laser cladding process. The coating consists of spherical CrxSy particles, primary γ-Ni dendrite, interdendritic eutectic (γ-Ni+NiMo) and precipitated NiMo. The precipitated NiMo was fine and uniformly distributed in primary γ-Ni dendrite. The calculated results and experimental data indicate that the solidification process in the coating during laser cladding process was liquid→liquid+CrxSy→ liquid+CrxSy+γ-Ni→liquid+CrxSy+γ-Ni+ eutectic (γ-Ni+NiMo). A solid state phase transformation (fine and uniformly distributed NiMo precipitated from γ-Ni) occurred after the solidification process. The calculations agree well with the experimental data and it is helpful to understand the phase transformation and microstructure evolution in the coating.

  6. Computed tomographic beam-hardening artefacts: mathematical characterization and analysis

    PubMed Central

    Park, Hyoung Suk; Chung, Yong Eun; Seo, Jin Keun

    2015-01-01

    This paper presents a mathematical characterization and analysis of beam-hardening artefacts in X-ray computed tomography (CT). In the field of dental and medical radiography, metal artefact reduction in CT is becoming increasingly important as artificial prostheses and metallic implants become more widespread in ageing populations. Metal artefacts are mainly caused by the beam-hardening of polychromatic X-ray photon beams, which causes mismatch between the actual sinogram data and the data model being the Radon transform of the unknown attenuation distribution in the CT reconstruction algorithm. We investigate the beam-hardening factor through a mathematical analysis of the discrepancy between the data and the Radon transform of the attenuation distribution at a fixed energy level. Separation of cupping artefacts from beam-hardening artefacts allows causes and effects of streaking artefacts to be analysed. Various computer simulations and experiments are performed to support our mathematical analysis. PMID:25939628

  7. Computed tomographic beam-hardening artefacts: mathematical characterization and analysis.

    PubMed

    Park, Hyoung Suk; Chung, Yong Eun; Seo, Jin Keun

    2015-06-13

    This paper presents a mathematical characterization and analysis of beam-hardening artefacts in X-ray computed tomography (CT). In the field of dental and medical radiography, metal artefact reduction in CT is becoming increasingly important as artificial prostheses and metallic implants become more widespread in ageing populations. Metal artefacts are mainly caused by the beam-hardening of polychromatic X-ray photon beams, which causes mismatch between the actual sinogram data and the data model being the Radon transform of the unknown attenuation distribution in the CT reconstruction algorithm. We investigate the beam-hardening factor through a mathematical analysis of the discrepancy between the data and the Radon transform of the attenuation distribution at a fixed energy level. Separation of cupping artefacts from beam-hardening artefacts allows causes and effects of streaking artefacts to be analysed. Various computer simulations and experiments are performed to support our mathematical analysis. PMID:25939628

  8. RHOBOT: Radiation hardened robotics

    SciTech Connect

    Bennett, P.C.; Posey, L.D.

    1997-10-01

    A survey of robotic applications in radioactive environments has been conducted, and analysis of robotic system components and their response to the varying types and strengths of radiation has been completed. Two specific robotic systems for accident recovery and nuclear fuel movement have been analyzed in detail for radiation hardness. Finally, a general design approach for radiation-hardened robotics systems has been developed and is presented. This report completes this project which was funded under the Laboratory Directed Research and Development program.

  9. Precipitation hardening austenitic superalloys

    DOEpatents

    Korenko, Michael K.

    1985-01-01

    Precipitation hardening, austenitic type superalloys are described. These alloys contain 0.5 to 1.5 weight percent silicon in combination with about 0.05 to 0.5 weight percent of a post irradiation ductility enhancing agent selected from the group of hafnium, yttrium, lanthanum and scandium, alone or in combination with each other. In addition, when hafnium or yttrium are selected, reductions in irradiation induced swelling have been noted.

  10. Numerical estimation of phase transformations in solid state during Yb:YAG laser heating of steel sheets

    SciTech Connect

    Kubiak, Marcin Piekarska, Wiesława; Domański, Tomasz; Saternus, Zbigniew; Stano, Sebastian

    2015-03-10

    This work concerns the numerical modeling of heat transfer and phase transformations in solid state occurring during the Yb:YAG laser beam heating process. The temperature field is obtained by the numerical solution into transient heat transfer equation with convective term. The laser beam heat source model is developed using the Kriging interpolation method with experimental measurements of Yb:YAG laser beam profile taken into account. Phase transformations are calculated on the basis of Johnson - Mehl - Avrami (JMA) and Koistinen - Marburger (KM) kinetics models as well as continuous heating transformation (CHT) and continuous cooling transformation (CCT) diagrams for S355 steel. On the basis of developed numerical algorithms 3D computer simulations are performed in order to predict temperature history and phase transformations in Yb:YAG laser heating process.

  11. Plasma Plume Oscillations Monitoring during Laser Welding of Stainless Steel by Discrete Wavelet Transform Application

    PubMed Central

    Sibillano, Teresa; Ancona, Antonio; Rizzi, Domenico; Lupo, Valentina; Tricarico, Luigi; Lugarà, Pietro Mario

    2010-01-01

    The plasma optical radiation emitted during CO2 laser welding of stainless steel samples has been detected with a Si-PIN photodiode and analyzed under different process conditions. The discrete wavelet transform (DWT) has been used to decompose the optical signal into various discrete series of sequences over different frequency bands. The results show that changes of the process settings may yield different signal features in the range of frequencies between 200 Hz and 30 kHz. Potential applications of this method to monitor in real time the laser welding processes are also discussed. PMID:22319311

  12. Controlling the femtosecond laser-driven transformation of dicyclopentadiene into cyclopentadiene

    PubMed Central

    Goswami, Tapas; Das, Dipak K.; Goswami, Debabrata

    2013-01-01

    Dynamics of the chemical transformation of dicyclopentadiene into cyclopentadiene in a supersonic molecular beam is elucidated using femtosecond time-resolved degenerate pump–probe mass spectrometry. Control of this ultrafast chemical reaction is achieved by using linearly chirped frequency modulated pulses. We show that negatively chirped femtosecond laser pulses enhance the cyclopentadiene photoproduct yield by an order of magnitude as compared to that of the unmodulated or the positively chirped pulses. This demonstrates that the phase structure of femtosecond laser pulse plays an important role in determining the outcome of a chemical reaction. PMID:24098059

  13. Surface structural transformation of sintered alumina induced by excimer laser irradiation

    NASA Astrophysics Data System (ADS)

    Dupas-Bruzek, C.; Laude, L. D.; Langenhorst, F.; Kolev, K.

    2003-04-01

    Laser surface processing of ceramics is important for several structural, tribological, optical and electronic applications. However, little is known on the transformation mechanism of alumina under excimer laser irradiation. In this work, a sintered alumina type was typically irradiated at 0.8 J cm-2 and cooled at two drastically different rates. Optical investigations on the irradiated specimens allow to conclude that the amount of transformation products is very much dependant on the cooling rates. Transmission electron microscopy observations show that the transformation product is constituted of an amorphous matrix in which are embedded either (i) copper grains (size up to 1 μm) in slowly cooled samples or (ii) smaller copper or CuAl2O4 spinel grains (size up to 100 nm) in rapidly cooled samples. The cement that is present in the starting material at grain boundaries is found to play an important role on the formation of the new amorphous or crystalline materials. All the copper grains exhibit a <120> common zone axis perpendicular to the irradiated surface and parallel to the bulk-to-surface thermal gradient, which drives that preferred orientation. These results reveal the details of the phenomenology of the laser-induced material transformation. This latter decomposes into (i) the incipient formation of tiny γ-Al2O3 nuclei, (ii) integration of Cu ions present in the melt into these tiny γ-Al2O3 nuclei that transform into CuAl2O4 spinel, and (iii) further sedimentation of Cu ions onto the resulting spinel grains acting as nucleation centers and finally formation of larger copper-rich grains. The minimum nucleation rate of crystalline grains is estimated to be equal to 1024 cm-3 s-1, while the growth rate is of the order of 0.1 m s-1 in both samples. Both bulk thermal diffusive and convective transports control the transformation of matter.

  14. Nuclear effects hardened shelters

    NASA Astrophysics Data System (ADS)

    Lindke, Paul

    1990-11-01

    The Houston Fearless 76 Government Projects Group has been actively engaged for more than twenty-five years as a sub-contractor and currently as a prime contractor in the design, manufacture, repair and logistics support of custom mobile ground stations and their equipment accommodations. Other associated products include environmental control units (ECU's), mobilizers for shelters and a variety of mobile power generation units (MPU's). Since 1984, Houston Fearless 76 has designed and manufactured four 8' x 8' x 22' nuclear hardened mobile shelters. These shelters were designed to contain electronic data processing/reduction equipment. One shelter is currently being operated by the Air Force as a Defense Intelligence Agency (DIA) approved and certified Special Corrpartmented Information Facility (SCIF). During the development and manufacturing process of the shelters, we received continual technical assistance and design concept evaluations from Science Applications International Corporation (SAIC) Operations Analysis and Logistics Engineering Division and the Nondestructive Inspection Lab at McClellan AFB. SAIC was originally employed by the Air Force to design the nuclear hardening specifications applied to these shelters. The specific levels of hardening to which the shelters were designed are classified and will not be mentioned during this presentation.

  15. Phase-space analysis for ionization processes in the laser-atom interaction using Gabor transformation

    NASA Astrophysics Data System (ADS)

    Shu, X. F.; Liu, S. B.; Song, H. Y.

    2016-04-01

    In this paper, the ionization processes during laser-atom interaction are investigated in phase-space using Gabor transformation. Based on the time-dependent Schrödinger equation (TDSE), the depletion of the whole system caused by the mask function is taken into consideration in calculating the plasma density. We obtain the momentum distribution via the Gabor transformation of the escaping portions of the time-dependent wave packet at the detector-like points on the interior boundaries from which the kinetic energies carried by the escaping portions are calculated.

  16. Pressure-induced phase transformations during femtosecond-laser doping of silicon

    NASA Astrophysics Data System (ADS)

    Smith, Matthew J.; Lin, Yu-Ting; Sher, Meng-Ju; Winkler, Mark T.; Mazur, Eric; Gradečak, Silvija

    2011-09-01

    Silicon hyperdoped with chalcogens via femtosecond-laser irradiation exhibits unique near-unity sub-bandgap absorptance extending into the infrared region. The intense light-matter interactions that occur during femtosecond-laser doping produce pressure waves sufficient to induce phase transformations in silicon, resulting in the formation of metastable polymorphic phases, but their exact formation mechanism and influence on the doping process are still unknown. We report direct observations of these phases, describe their formation and distribution, and consider their potential impact on sub-bandgap absorptance. Specifically, the transformation from diamond cubic Si-I to pressure-induced polymorphic crystal structures (amorphous Si, Si-XII, and Si-III) during femtosecond-laser irradiation was investigated using scanning electron microscopy, Raman spectroscopy, and transmission electron microscopy. Amorphous Si, Si-XII, and Si-III were found to form in femtosecond-laser doped silicon regardless of the presence of a gaseous or thin-film dopant precursor. The rate of pressure loading and unloading induced by femtosecond-laser irradiation kinetically limits the formation of pressure-induced phases, producing regions of amorphous Si 20 to 200 nm in size and nanocrystals of Si-XII and Si-III. The surface texturing that occurs during femtosecond-laser irradiation produces inhomogeneous pressure distributions across the surface and causes delayed development of high-pressure silicon polymorphs over many laser pulses. Finally, we find that the polymorph phases disappear during annealing more rapidly than the sub-bandgap absorptance decreases, enabling us to decouple these two processes through post-treatment annealing.

  17. Observation of the continuous transformation of a four level laser into a two level system

    SciTech Connect

    Hewitt, J. D.; Readle, J. D.; Eden, J. G.

    2012-08-13

    A longstanding and fundamental question of laser and maser physics concerns the energy separation ({Delta}{epsilon}) required between the pumped and lasing states of a three (or four) level system. We observe a four level laser gradually transform into a two level (nonlasing) system by photoassociating Cs-Ar thermal atomic pairs and monitoring subsequent stimulated emission on the 6p{sup 2}P{sub 3/2} {yields} 6s{sup 2}S{sub 1/2} (D{sub 2}) transition of Cs at 852.1 nm. Laser excitation spectra demonstrate that the value of {Delta}{epsilon} below which the system rapidly assumes the form of a two level structure and lasing ceases is {approx}0.7kT which corresponds to a Boltzmann factor (exp[-{Delta}{epsilon}/kT]) of 0.5.

  18. Femtosecond laser induced coordination transformation and migration of ions in sodium borate glasses

    SciTech Connect

    Liu Yin; Zhu Bin; Wang Li; Qiu Jianrong; Dai Ye; Ma Hongliang

    2008-03-24

    We report on the coordination transformation of B{sup 3+} ions and migration of Na{sup +} and O{sup 2-} ions in sodium borate glasses, induced by 250 kHz, 800 nm femtosecond laser irradiation. Micro-Raman spectra show that the ratio of the integrated intensity of the two peaks at 806 and 774 cm{sup -1} decreases at first and then increases with increasing distance from the center of the laser modified zone. Electron dispersive x-ray spectra show that a portion of Na{sup +} and O{sup 2-} ions migrate from the vicinity of focal point after the femtosecond laser irradiation. A possible mechanism is proposed to explain the observed phenomena.

  19. Rational Chebyshev spectral transform for the dynamics of broad-area laser diodes

    SciTech Connect

    Javaloyes, J.

    2015-10-01

    This manuscript details the use of the rational Chebyshev transform for describing the transverse dynamics of broad-area laser diodes and amplifiers. This spectral method can be used in combination with the delay algebraic equations approach developed in [1], which substantially reduces the computation time. The theory is presented in such a way that it encompasses the case of the Fourier spectral transform presented in [2] as a particular case. It is also extended to the consideration of index guiding with an arbitrary transverse profile. Because their domain of definition is infinite, the convergence properties of the Chebyshev rational functions allow handling the boundary conditions with higher accuracy than with the previously studied Fourier transform method. As practical examples, we solve the beam propagation problem with and without index guiding: we obtain excellent results and an improvement of the integration time between one and two orders of magnitude as compared with a fully distributed two dimensional model.

  20. Influence of Laser Peening on Phase Transformation and Corrosion Resistance of AISI 321 steel

    NASA Astrophysics Data System (ADS)

    Karthik, D.; Swaroop, S.

    2016-06-01

    The objective of this study is to investigate the influence of laser peening without coating (LPwC) on austenitic to martensitic (γ → α') phase transformation and corrosion behavior of austenitic stainless steel AISI 321 in 3.5% NaCl environment. Results indicate that LPwC induces a large compressive residual stresses of nearly -854 MPa and γ → α' phase transformation of about 18% (volume fraction). Microstructures of peened surface confirmed the γ → α' phase transformation and showed no grain refinement. Hardness increased slightly with a case depth of 900 μm. Despite the smaller surface roughness introduced, corrosion resistance improved after peening due to compressive residual stresses.

  1. Influence of Laser Peening on Phase Transformation and Corrosion Resistance of AISI 321 steel

    NASA Astrophysics Data System (ADS)

    Karthik, D.; Swaroop, S.

    2016-07-01

    The objective of this study is to investigate the influence of laser peening without coating (LPwC) on austenitic to martensitic (γ → α') phase transformation and corrosion behavior of austenitic stainless steel AISI 321 in 3.5% NaCl environment. Results indicate that LPwC induces a large compressive residual stresses of nearly -854 MPa and γ → α' phase transformation of about 18% (volume fraction). Microstructures of peened surface confirmed the γ → α' phase transformation and showed no grain refinement. Hardness increased slightly with a case depth of 900 μm. Despite the smaller surface roughness introduced, corrosion resistance improved after peening due to compressive residual stresses.

  2. Nonlinear-optical transformation of nanosecond laser pulses and controlled supercontinuum generation in photonic-crystal fibers

    SciTech Connect

    Fedotov, I. V. Fedotov, A. B.; Zheltikov, A. M.

    2007-11-15

    Photonic-crystal fibers are shown to allow efficient spectral transformation of nanosecond laser pulses through parametric four-wave mixing and stimulated Raman scattering. Regimes providing highly efficient transformation of nanosecond laser pulses into white-light broadband radiation (supercontinuum) are identified. A strong parametric coupling between Stokes and anti-Stokes Raman sidebands around the wavelength of zero group-velocity dispersion is shown to increase the bandwidth and to improve the spectral quality of supercontinuum radiation.

  3. The mechanism of the surface morphology transformation for the carbon nanotube thin film irradiated via excimer laser

    SciTech Connect

    Chien, Yun-Shan; Lee, I-Che; Yang, Po-Yu; Wang, Chao-Lung; Tsai, Wan-Lin; Wang, Kuang-Yu; Chou, Chia-Hsin; Cheng, Huang-Chung

    2013-05-06

    In this paper, the surface morphology transformation of the sprayed carbon nanotube (CNT) thin film irradiated with the excimer laser has been systematically investigated. Under the excimer-laser irradiation, two phenomena, including the annealing and ablation effects, were found to be dependent on the incident laser energy and overlapping ratios. Moreover, the extremely high protrusions would be produced in the interface between the annealing and ablation regions. The mechanism of the CNT thin film under the excimer laser irradiation was, therefore, proposed to derive the surface morphology modifications and the further reinforced crystallinity with proper laser energy densities and overlapping ratios.

  4. Tomography of homogenized laser-induced plasma by Radon transform technique

    NASA Astrophysics Data System (ADS)

    Eschlböck-Fuchs, S.; Demidov, A.; Gornushkin, I. B.; Schmid, T.; Rössler, R.; Huber, N.; Panne, U.; Pedarnig, J. D.

    2016-09-01

    Tomography of a laser-induced plasma in air is performed by inverse Radon transform of angle-resolved plasma images. Plasmas were induced by single laser pulses (SP), double pulses (DP) in collinear geometry, and by a combination of single laser pulses with pulsed arc discharges (SP-AD). Images of plasmas on metallurgical steel slags were taken at delay times suitable for calibration-free laser-induced breakdown spectroscopy (CF-LIBS). Delays ranged from few microseconds for SP and DP up to tens of microseconds for SP-AD excitation. The white-light and the spectrally resolved emissivity ε(x,y,z) was reconstructed for the three plasma excitation schemes. The electron number density Ne(x,y,z) and plasma temperature Te(x,y,z) were determined from Mg and Mn emission lines in reconstructed spectra employing the Saha-Boltzmann plot method. The SP plasma revealed strongly inhomogeneous emissivity and plasma temperature. Re-excitation of plasma by a second laser pulse (DP) and by an arc discharge (SP-AD) homogenized the plasma and reduced the spatial variation of ε and Te. The homogenization of a plasma is a promising approach to increase the accuracy of calibration-free LIBS analysis of complex materials.

  5. Imaging Fourier transform spectroscopy of the boundary layer plume from laser irradiated polymers and carbon materials

    NASA Astrophysics Data System (ADS)

    Acosta, Roberto I.

    The high-energy laser (HEL) lethality community needs for enhanced laser weapons systems requires a better understanding of a wide variety of emerging threats. In order to reduce the dimensionality of laser-materials interaction it is necessary to develop novel predictive capabilities of these events. The objective is to better understand the fundamentals of laser lethality testing by developing empirical models from hyperspectral imagery, enabling a robust library of experiments for vulnerability assessments. Emissive plumes from laser irradiated fiberglass reinforced polymers (FRP), poly(methyl methacrylate) (PMMA) and porous graphite targets were investigated primarily using a mid-wave infrared (MWIR) imaging Fourier transform spectrometer (FTS). Polymer and graphite targets were irradiated with a continuous wave (cw) fiber lasers. Data was acquired with a spectral resolution of 2 cm-1 and spatial resolution as high as 0.52 mm2 per pixel. Strong emission from H2O, CO, CO2 and hydrocarbons were observed in the MWIR between 1900-4000 cm-1. A single-layer radiative transfer model was developed to estimate spatial maps of temperature and column densities of CO and CO2 from the hyperspectral imagery of the boundary layer plume. The spectral model was used to compute the absorption cross sections of CO and CO2, using spectral line parameters from the high temperature extension of the HITRAN. Also, spatial maps of gas-phase temperature and methyl methacrylate (MMA) concentration were developed from laser irradiated carbon black-pigmented PMMA at irradiances of 4-22 W/cm2. Global kinetics interplay between heterogeneous and homogeneous combustion kinetics are shown from experimental observations at high spatial resolutions. Overall the boundary layer profile at steady-state is consistent with CO being mainly produced at the surface by heterogeneous reactions followed by a rapid homogeneous combustion in the boundary layer towards buoyancy.

  6. Cross modulation method of transformation of the spatial coherence of pulsed laser radiation in a nonlinear medium

    SciTech Connect

    Kitsak, M A; Kitsak, A I

    2008-04-30

    The cross modulation method of transformation of the spatial coherence of low-power pulsed laser radiation in a nonlinear medium is proposed. The method is realised experimentally in a multimode optical fibre. The estimates of the degree of spatial coherence of radiation subjected to the phase cross modulation demonstrated the high efficiency of this radiation decorrelation mechanism. (control of laser radiation parameters)

  7. Highly Reproducible Laser Beam Scanning Device for an Internal Source Laser Desorption Microprobe Fourier Transform Mass Spectrometer

    SciTech Connect

    Scott, Jill Rennee; Tremblay, Paul Leland

    2002-03-01

    Traditionally, mass spectrometry has relied on manipulating the sample target to provide scanning capabilities for laser desorption microprobes. This has been problematic for an internal source laser desorption Fourier transform mass spectrometer (LD-FTMS) because of the high magnetic field (7 Tesla) and geometric constraints of the superconducting magnet bore. To overcome these limitations, we have implemented a unique external laser scanning mechanism for an internal source LD-FTMS. This mechanism provides adjustable resolution enhancement so that the spatial resolution at the target is not limited to that of the stepper motors at the light source (~5 µm/step). The spatial resolution is now limited by the practical optical diffraction limit of the final focusing lens. The scanning mechanism employs a virtual source that is wavelength independent up to the final focusing lens, which can be controlled remotely to account for focal length dependence on wavelength. A binary index provides an automatic alignment feature. The virtual source is located ~9 ft from the sample; therefore, it is completely outside of the vacuum system and beyond the 50 G line of the fringing magnetic field. To eliminate reproducibility problems associated with vacuum pump vibrations, we have taken advantage of the magnetic field inherent to the FTMS to utilize Lenz's law for vibrational dampening. The LD-FTMS microprobe has exceptional reproducibility, which enables successive mapping sequences for depth-profiling studies.

  8. Highly reproducible laser beam scanning device for an internal source laser desorption microprobe Fourier transform mass spectrometer

    NASA Astrophysics Data System (ADS)

    Scott, Jill R.; Tremblay, Paul L.

    2002-03-01

    Traditionally, mass spectrometry has relied on manipulating the sample target to provide scanning capabilities for laser desorption microprobes. This has been problematic for an internal source laser desorption Fourier transform mass spectrometer (LD-FTMS) because of the high magnetic field (7 Tesla) and geometric constraints of the superconducting magnet bore. To overcome these limitations, we have implemented a unique external laser scanning mechanism for an internal source LD-FTMS. This mechanism provides adjustable resolution enhancement so that the spatial resolution at the target is not limited to that of the stepper motors at the light source (˜5 μm/step). The spatial resolution is now limited by the practical optical diffraction limit of the final focusing lens. The scanning mechanism employs a virtual source that is wavelength independent up to the final focusing lens, which can be controlled remotely to account for focal length dependence on wavelength. A binary index provides an automatic alignment feature. The virtual source is located ˜9 ft from the sample; therefore, it is completely outside of the vacuum system and beyond the 50 G line of the fringing magnetic field. To eliminate reproducibility problems associated with vacuum pump vibrations, we have taken advantage of the magnetic field inherent to the FTMS to utilize Lenz's law for vibrational dampening. The LD-FTMS microprobe has exceptional reproducibility, which enables successive mapping sequences for depth-profiling studies.

  9. Transformation of irregular shaped silver nanostructures into nanoparticles by under water pulsed laser melting.

    PubMed

    Yadavali, S; Sandireddy, V P; Kalyanaraman, R

    2016-05-13

    The ability to easily manufacture nanostructures with a desirable attribute, such as well-defined size and shape, especially from any given initial shapes or sizes of the material, will be helpful towards accelerating the use of nanomaterials in various applications. In this work we report the transformation of discontinuous irregular nanostructures (DIN) of silver metal by rapid heating under a bulk fluid layer. Ag films were changed into DIN by dewetting in air and subsequently heated by nanosecond laser pulses under water. Our findings show that the DIN first ripens into elongated structures and then breaks up into nanoparticles. From the dependence of this behavior on laser fluence we found that under water irradiation reduced the rate of ripening and also decreased the characteristic break-up length scale of the elongated structures. This latter result was qualitatively interpreted as arising from a Rayleigh-Plateau instability modified to yield significantly smaller length scales than the classical process due to pressure gradients arising from the rapid evaporation of water during laser melting. These results demonstrate that it is possible to fabricate a dense collection of monomodally sized Ag nanoparticles with significantly enhanced plasmonic quality starting from the irregular shaped materials. This can be beneficial towards transforming discontinuous Ag films into nanostructures with useful plasmonic properties, that are relevant for biosensing applications. PMID:27041091

  10. Transformation of irregular shaped silver nanostructures into nanoparticles by under water pulsed laser melting

    NASA Astrophysics Data System (ADS)

    Yadavali, S.; Sandireddy, V. P.; Kalyanaraman, R.

    2016-05-01

    The ability to easily manufacture nanostructures with a desirable attribute, such as well-defined size and shape, especially from any given initial shapes or sizes of the material, will be helpful towards accelerating the use of nanomaterials in various applications. In this work we report the transformation of discontinuous irregular nanostructures (DIN) of silver metal by rapid heating under a bulk fluid layer. Ag films were changed into DIN by dewetting in air and subsequently heated by nanosecond laser pulses under water. Our findings show that the DIN first ripens into elongated structures and then breaks up into nanoparticles. From the dependence of this behavior on laser fluence we found that under water irradiation reduced the rate of ripening and also decreased the characteristic break-up length scale of the elongated structures. This latter result was qualitatively interpreted as arising from a Rayleigh–Plateau instability modified to yield significantly smaller length scales than the classical process due to pressure gradients arising from the rapid evaporation of water during laser melting. These results demonstrate that it is possible to fabricate a dense collection of monomodally sized Ag nanoparticles with significantly enhanced plasmonic quality starting from the irregular shaped materials. This can be beneficial towards transforming discontinuous Ag films into nanostructures with useful plasmonic properties, that are relevant for biosensing applications.

  11. TRANSFORMATION

    SciTech Connect

    LACKS,S.A.

    2003-10-09

    Transformation, which alters the genetic makeup of an individual, is a concept that intrigues the human imagination. In Streptococcus pneumoniae such transformation was first demonstrated. Perhaps our fascination with genetics derived from our ancestors observing their own progeny, with its retention and assortment of parental traits, but such interest must have been accelerated after the dawn of agriculture. It was in pea plants that Gregor Mendel in the late 1800s examined inherited traits and found them to be determined by physical elements, or genes, passed from parents to progeny. In our day, the material basis of these genetic determinants was revealed to be DNA by the lowly bacteria, in particular, the pneumococcus. For this species, transformation by free DNA is a sexual process that enables cells to sport new combinations of genes and traits. Genetic transformation of the type found in S. pneumoniae occurs naturally in many species of bacteria (70), but, initially only a few other transformable species were found, namely, Haemophilus influenzae, Neisseria meningitides, Neisseria gonorrheae, and Bacillus subtilis (96). Natural transformation, which requires a set of genes evolved for the purpose, contrasts with artificial transformation, which is accomplished by shocking cells either electrically, as in electroporation, or by ionic and temperature shifts. Although such artificial treatments can introduce very small amounts of DNA into virtually any type of cell, the amounts introduced by natural transformation are a million-fold greater, and S. pneumoniae can take up as much as 10% of its cellular DNA content (40).

  12. New Devices For Controlling The Interaction Of High-Power Laser Light With Anorganic And Organic Materials

    NASA Astrophysics Data System (ADS)

    Greguss, Pal

    1989-01-01

    Two unconventional methods, which may be used in some cases to control heat conduction conditions responsible for secondary effects both in laser surgery and in laser material transformation, are presented. The tools developed for this purpose are based either on thermoelectrically controlled (TEC) or on thermodynamically controlled (TDC) temperature pattern generation around the acting laser beam. Using TEC laser scalpel secondary tissue damages may be avoided, while transformation hardening by laser radiation may be controlled through the thermodynamic effect known as Ranque-effect.

  13. Simultaneous fluorescence and breakdown spectroscopy of fresh and aging transformer oil immersed in paper using ArF excimer laser

    NASA Astrophysics Data System (ADS)

    Parvin, P.; Shoursheini, S. Z.; Khalilinejad, F.; Bavali, A.; Moshgel Gosha, M.; Mansouri, B.

    2012-11-01

    HV transformers are taken into account as the heart of the power distribution system. The on-line monitoring based on the oil analysis offers a rapid diagnostic technique to detect the probable faults. In fact, the transformer malfunctions can be detected using UV laser spectroscopic methods. Here, a novel technique is presented based on simultaneous laser induced fluorescence (LIF) and laser induced breakdown (LIB) spectroscopy for hyper sensitive identification of the oil degradation. Oil is mainly degraded due to the internal transformer faults such as overheating and partial discharge. The spectroscopic characteristics of oil in paper substrate were obtained due to ArF laser irradiation. It was shown that the amplitude of fluorescence signal increases when the oil suffers aging and degradation. A couple of additional characteristic carbon and Hα emissions appear in the corresponding breakdown spectra too.

  14. Laser spot tracking based on modified circular Hough transform and motion pattern analysis.

    PubMed

    Krstinić, Damir; Skelin, Ana Kuzmanić; Milatić, Ivan

    2014-01-01

    Laser pointers are one of the most widely used interactive and pointing devices in different human-computer interaction systems. Existing approaches to vision-based laser spot tracking are designed for controlled indoor environments with the main assumption that the laser spot is very bright, if not the brightest, spot in images. In this work, we are interested in developing a method for an outdoor, open-space environment, which could be implemented on embedded devices with limited computational resources. Under these circumstances, none of the assumptions of existing methods for laser spot tracking can be applied, yet a novel and fast method with robust performance is required. Throughout the paper, we will propose and evaluate an efficient method based on modified circular Hough transform and Lucas-Kanade motion analysis. Encouraging results on a representative dataset demonstrate the potential of our method in an uncontrolled outdoor environment, while achieving maximal accuracy indoors. Our dataset and ground truth data are made publicly available for further development. PMID:25350502

  15. Chemical transformations of the polyimide Kapton brought about by ultraviolet laser radiation

    NASA Astrophysics Data System (ADS)

    Srinivasan, R.; Hall, R. R.; Loehle, W. D.; Wilson, W. D.; Allbee, D. C.

    1995-10-01

    By the use of ultraviolet laser pulses of microsecond and millisecond duration it is shown that the chemistry of the transformations of Kapton by UV laser radiation is strongly dependent on the intensity (power/unit area) of the laser beam. With these long pulses, the polymer was not ablated. The decomposition resulted in 51% of the polymer weight being converted to gaseous products consisting mostly of CO (67%), HCN (15%), C2H2 (12%), and some (<5%) CO2. The major solid product that remained was ``glassy'' carbon which was identified from its Raman spectrum. This material can be viewed as the product of the secondary addition reactions of the residue that is left after the loss of the gaseous products listed above. With 20 ms pulses, the evolution of the gaseous products increased linearly with intensity and the product composition was constant within the experimental uncertainty over a 12-fold range of intensity up to 50 kW/cm2 (≡1 kJ/cm2). These results show that pulses of duration much greater than ns do not lead to ablation even at fluences that are 104 greater than the threshold for ablation using nanosecond pulses. It is therefore more appropriate to view the ablation of this polymer by UV laser pulses of nanosecond duration as being due to the scaling of an intensity threshold rather than a fluence threshold as has become the practice.

  16. Laser Spot Tracking Based on Modified Circular Hough Transform and Motion Pattern Analysis

    PubMed Central

    Krstinić, Damir; Skelin, Ana Kuzmanić; Milatić, Ivan

    2014-01-01

    Laser pointers are one of the most widely used interactive and pointing devices in different human-computer interaction systems. Existing approaches to vision-based laser spot tracking are designed for controlled indoor environments with the main assumption that the laser spot is very bright, if not the brightest, spot in images. In this work, we are interested in developing a method for an outdoor, open-space environment, which could be implemented on embedded devices with limited computational resources. Under these circumstances, none of the assumptions of existing methods for laser spot tracking can be applied, yet a novel and fast method with robust performance is required. Throughout the paper, we will propose and evaluate an efficient method based on modified circular Hough transform and Lucas–Kanade motion analysis. Encouraging results on a representative dataset demonstrate the potential of our method in an uncontrolled outdoor environment, while achieving maximal accuracy indoors. Our dataset and ground truth data are made publicly available for further development. PMID:25350502

  17. High resolution infrared spectroscopy of planetary molecules using diode lasers and Fourier transform spectrometers

    NASA Technical Reports Server (NTRS)

    Jennings, Donald E.

    1990-01-01

    Modern observations of infrared molecular lines in planets are performed at spectral resolutions which are as high as those available in the laboratory. Analysis of such data requires laboratory measurements at the highest possible resolution, which also yield accurate line positions and intensities. For planetary purposes the spectrometer must be coupled to sample cells which can be reduced in temperature and varied in pressure. An approach which produces the full range of required molecular line parameters uses a combination of tunable diode lasers and Fourier transform spectrometers (FTS). The FTS provides board spectral coverage and good calibration accuracy, while the diode laser can be used to study those regions which are not resolved by the FTS.

  18. Hidden corrosion detection in aircraft aluminum structures using laser ultrasonics and wavelet transform signal analysis.

    PubMed

    Silva, M Z; Gouyon, R; Lepoutre, F

    2003-06-01

    Preliminary results of hidden corrosion detection in aircraft aluminum structures using a noncontact laser based ultrasonic technique are presented. A short laser pulse focused to a line spot is used as a broadband source of ultrasonic guided waves in an aluminum 2024 sample cut from an aircraft structure and prepared with artificially corroded circular areas on its back surface. The out of plane surface displacements produced by the propagating ultrasonic waves were detected with a heterodyne Mach-Zehnder interferometer. Time-frequency analysis of the signals using a continuous wavelet transform allowed the identification of the generated Lamb modes by comparison with the calculated dispersion curves. The presence of back surface corrosion was detected by noting the loss of the S(1) mode near its cutoff frequency. This method is applicable to fast scanning inspection techniques and it is particularly suited for early corrosion detection. PMID:12782263

  19. Detection and measurement of electroreflectance on quantum cascade laser device using Fourier transform infrared microscope

    SciTech Connect

    Enobio, Eli Christopher I.; Ohtani, Keita; Ohno, Yuzo; Ohno, Hideo

    2013-12-02

    We demonstrate the use of a Fourier Transform Infrared microscope system to detect and measure electroreflectance (ER) from mid-infrared quantum cascade laser (QCL) device. To characterize intersubband transition (ISBT) energies in a functioning QCL device, a microscope is used to focus the probe on the QCL cleaved mirror. The measured ER spectra exhibit resonance features associated to ISBTs under applied electric field in agreement with the numerical calculations and comparable to observed photocurrent, and emission peaks. The method demonstrates the potential as a characterization tool for QCL devices.

  20. Transform-limited pulses generated by an actively Q-switched distributed fiber laser.

    PubMed

    Cuadrado-Laborde, C; Pérez-Millán, P; Andrés, M V; Díez, A; Cruz, J L; Barmenkov, Yu O

    2008-11-15

    A single-mode, transform-limited, actively Q-switched distributed-feedback fiber laser is presented, based on a new in-line acoustic pulse generator. Our technique permits a continuous adjustment of the repetition rate that modulates the Q factor of the cavity. Optical pulses of 800 mW peak power, 32 ns temporal width, and up to 20 kHz repetition rates were obtained. The measured linewidth demonstrates that these pulses are transform limited: 6 MHz for a train of pulses of 10 kHz repetition rate, 80 ns temporal width, and 60 mW peak power. Efficient excitation of spontaneous Brillouin scattering is demonstrated. PMID:19015677

  1. TRANSFORMER

    DOEpatents

    Baker, W.R.

    1959-08-25

    Transformers of a type adapted for use with extreme high power vacuum tubes where current requirements may be of the order of 2,000 to 200,000 amperes are described. The transformer casing has the form of a re-entrant section being extended through an opening in one end of the cylinder to form a coaxial terminal arrangement. A toroidal multi-turn primary winding is disposed within the casing in coaxial relationship therein. In a second embodiment, means are provided for forming the casing as a multi-turn secondary. The transformer is characterized by minimized resistance heating, minimized external magnetic flux, and an economical construction.

  2. Adaptive-feedback spectral-phase control for interactions with transform-limited ultrashort high-power laser pulses.

    PubMed

    Liu, Cheng; Zhang, Jun; Chen, Shouyuan; Golovin, Gregory; Banerjee, Sudeep; Zhao, Baozhen; Powers, Nathan; Ghebregziabher, Isaac; Umstadter, Donald

    2014-01-01

    Fourier-transform-limited light pulses were obtained at the laser-plasma interaction point of a 100-TW peak-power laser in vacuum. The spectral-phase distortion induced by the dispersion mismatching between the stretcher, compressor, and dispersive materials was fully compensated for by means of an adaptive closed-loop. The coherent temporal contrast on the sub-picosecond time scale was two orders of magnitude higher than that without adaptive control. This novel phase control capability enabled the experimental study of the dependence of laser wakefield acceleration on the spectral phase of intense laser light. PMID:24365827

  3. Surface oxidation and phase transformation of the stainless steel by hybrid laser-waterjet impact

    NASA Astrophysics Data System (ADS)

    Weiss, L.; Aillerie, M.; Tazibt, A.; Tidu, A.

    2014-09-01

    Hybrid jets (laser guided by water jet) are commonly used in the area of microelectronics for cutting thin wafer plates and for the design of special pieces. In this context, the hybrid jet works with a low power and low pressure. Efforts are made to apply and to improve this hybrid technology for cutting thicker metallic materials. In order to facilitate this development, we have studied the effects induced by a water jet-laser system coupled to the same point on a metallic material. The pressure of the water jet is about 1 MPa and the power of the laser source is about 400 W, which is much higher than the actual hybrid jet power. As a result, in the case of 301 L steel plates, we have noticed the formation of a magnetite layer around the cut in accordance with the high temperature reactions between water and iron, but, surprisingly, in this case, the reaction is practically instantaneous. A small percentage of hematite also appears, from a secondary reaction of reduction of magnetite. By using different techniques (Raman spectroscopy, optical microscopy, SEM, XRD…) we have observed, firstly, that the width of the oxidized zone is proportional to the cutting speed and on the other hand, that there exists a phase transformation in a small heat-affected zone, consistent with the hybrid jets literature.

  4. Matrix-assisted laser desorption fourier transform mass spectrometry for biological compounds

    SciTech Connect

    Hettich, R.; Buchanan, M.

    1990-01-01

    The recent development of matrix-assisted UV laser desorption (LD) mass spectrometry has made possible the ionization and detection of extremely large molecules (with molecular weights exceeding 100,000 Daltons). This technique has generated enormous interest in the biological community for the direct examination of large peptides and oligonucleotides. Although this matrix-assisted ionization method has been developed and used almost exclusively with time-of-flight (TOF) mass spectrometers, research is currently in progress to demonstrate this technique with trapped ion mass spectrometers, such as Fourier transform ion cyclotron resonance mass spectrometry (FTMS). The potential capabilities of FTMS for wide mass range, high resolution measurement, and ion trapping experiments suggest that this instrumental technique should be useful for the detailed structural characterization of large ions generated by the matrix-assisted technique. We have recently demonstrated that matrix-assisted ultraviolet laser desorption can be successfully used with FTMS for the ionization of small peptides. The objective of this report is to summarize the application and current limitations of matrix-assisted laser desorption FTMS for the characterization of peptides and oligonucleotides at the isomeric level. 4 refs., 3 figs., 2 tabs.

  5. System-Level Radiation Hardening

    NASA Technical Reports Server (NTRS)

    Ladbury, Ray

    2014-01-01

    Although system-level radiation hardening can enable the use of high-performance components and enhance the capabilities of a spacecraft, hardening techniques can be costly and can compromise the very performance designers sought from the high-performance components. Moreover, such techniques often result in a complicated design, especially if several complex commercial microcircuits are used, each posing its own hardening challenges. The latter risk is particularly acute for Commercial-Off-The-Shelf components since high-performance parts (e.g. double-data-rate synchronous dynamic random access memories - DDR SDRAMs) may require other high-performance commercial parts (e.g. processors) to support their operation. For these reasons, it is essential that system-level radiation hardening be a coordinated effort, from setting requirements through testing up to and including validation.

  6. Evidences for direct magnetic patterning via diffusive transformations using femtosecond laser interferometry

    NASA Astrophysics Data System (ADS)

    Polushkin, N. I.; Oliveira, V.; Conde, O.; Vilar, R.; Drozdov, Yu. N.; Apolinário, A.; García-García, A.; Teixeira, J. M.; Kakazei, G. N.

    2012-09-01

    The application of femtosecond laser interferometry to direct patterning of thin-film magnetic alloys is demonstrated. The formation of stripe gratings with submicron periodicities is achieved in Fe1-xVx (x = 18-34 wt. %) layers, with a difference in magnetic moments up to Δμ/μ ˜ 20 between adjacent stripes but without any significant development of the topographical relief (<1% of the film thickness). The produced gratings exhibit a robust effect of their anisotropy shape on magnetization curves in the film plane. The obtained data witness ultrafast diffusive transformations associated with the process of spinodal decomposition and demonstrate an opportunity for producing magnetic nanostructures with engineered properties upon this basis.

  7. Gaussian laser beam transformation into an optical vortex beam by helical lens

    NASA Astrophysics Data System (ADS)

    Janicijevic, Ljiljana; Topuzoski, Suzana

    2016-01-01

    In this article, we investigate the Fresnel diffraction characteristics of the hybrid optical element which is a combination of a spiral phase plate (SPP) with topological charge p and a thin lens with focal length f, named the helical lens (HL). As incident a Gaussian laser beam is treated, having its waist a distance ζ from the HL plane and its axis passing through the centre of the HL. It is shown that the SPP introduces a phase singularity of pth order to the incident beam, while the lens transforms the beam characteristic parameters. The output light beam is analyzed in detail: its characteristic parameters and focusing properties, amplitude and intensity distributions and the vortex rings profiles, and radii, at any z distance behind the HL plane, as well as in the near and far field.

  8. Wavelet transform based on the optimal wavelet pairs for tunable diode laser absorption spectroscopy signal processing.

    PubMed

    Li, Jingsong; Yu, Benli; Fischer, Horst

    2015-04-01

    This paper presents a novel methodology-based discrete wavelet transform (DWT) and the choice of the optimal wavelet pairs to adaptively process tunable diode laser absorption spectroscopy (TDLAS) spectra for quantitative analysis, such as molecular spectroscopy and trace gas detection. The proposed methodology aims to construct an optimal calibration model for a TDLAS spectrum, regardless of its background structural characteristics, thus facilitating the application of TDLAS as a powerful tool for analytical chemistry. The performance of the proposed method is verified using analysis of both synthetic and observed signals, characterized with different noise levels and baseline drift. In terms of fitting precision and signal-to-noise ratio, both have been improved significantly using the proposed method. PMID:25741689

  9. Microwave Frequency Transitions Requiring Laser Ablated Uranium Metal Discovered Using Chirp-Pulse Fourier Transform Spectroscopy

    NASA Astrophysics Data System (ADS)

    Long, B. E.; Cooke, S. A.

    2014-06-01

    A rod of depleted uranium metal (mp = 1,132° C) has been ablated with the fundamental operating frequency of a Nd:YAG laser. The resulting ablation plume of uranium was then mixed with argon gas and expanded between the transmit/receive horn antennae of a chirp-pulse Fourier transform microwave spectrometer. The recorded spectra show nine strong transitions which are not present when the laser is not used in the experimental procedure. A series of experiments in which the backing gas conditions were altered provides evidence that the nine observed transitions are carried by the same species. Should the transitions be from one species it is most likely an asymmetric top. The transitions persist even when ultra-pure argon is used as the sole backing gas. The oxide coating of the uranium metal likely provides a source of oxygen and, presently, the ``top" candidate for the unknown molecule is UO_3, which is known to have C_2v symmetry. Double resonance experiments are planned to aid transition assignments. A plausible explanation for an elusive assignment to date is the presence of pseudo-rotation.

  10. Process design of press hardening with gradient material property influence

    SciTech Connect

    Neugebauer, R.; Schieck, F.; Rautenstrauch, A.

    2011-05-04

    Press hardening is currently used in the production of automotive structures that require very high strength and controlled deformation during crash tests. Press hardening can achieve significant reductions of sheet thickness at constant strength and is therefore a promising technology for the production of lightweight and energy-efficient automobiles. The manganese-boron steel 22MnB5 have been implemented in sheet press hardening owing to their excellent hot formability, high hardenability, and good temperability even at low cooling rates. However, press-hardened components have shown poor ductility and cracking at relatively small strains. A possible solution to this problem is a selective increase of steel sheet ductility by press hardening process design in areas where the component is required to deform plastically during crash tests. To this end, process designers require information about microstructure and mechanical properties as a function of the wide spectrum of cooling rates and sequences and austenitizing treatment conditions that can be encountered in production environments. In the present work, a Continuous Cooling Transformation (CCT) diagram with corresponding material properties of sheet steel 22MnB5 was determined for a wide spectrum of cooling rates. Heating and cooling programs were conducted in a quenching dilatometer. Motivated by the importance of residual elasticity in crash test performance, this property was measured using a micro-bending test and the results were integrated into the CCT diagrams to complement the hardness testing results. This information is essential for the process design of press hardening of sheet components with gradient material properties.

  11. Process design of press hardening with gradient material property influence

    NASA Astrophysics Data System (ADS)

    Neugebauer, R.; Schieck, F.; Rautenstrauch, A.

    2011-05-01

    Press hardening is currently used in the production of automotive structures that require very high strength and controlled deformation during crash tests. Press hardening can achieve significant reductions of sheet thickness at constant strength and is therefore a promising technology for the production of lightweight and energy-efficient automobiles. The manganese-boron steel 22MnB5 have been implemented in sheet press hardening owing to their excellent hot formability, high hardenability, and good temperability even at low cooling rates. However, press-hardened components have shown poor ductility and cracking at relatively small strains. A possible solution to this problem is a selective increase of steel sheet ductility by press hardening process design in areas where the component is required to deform plastically during crash tests. To this end, process designers require information about microstructure and mechanical properties as a function of the wide spectrum of cooling rates and sequences and austenitizing treatment conditions that can be encountered in production environments. In the present work, a Continuous Cooling Transformation (CCT) diagram with corresponding material properties of sheet steel 22MnB5 was determined for a wide spectrum of cooling rates. Heating and cooling programs were conducted in a quenching dilatometer. Motivated by the importance of residual elasticity in crash test performance, this property was measured using a micro-bending test and the results were integrated into the CCT diagrams to complement the hardness testing results. This information is essential for the process design of press hardening of sheet components with gradient material properties.

  12. Feasibility study for detecting copper contaminants in transformer insulation using laser-induced breakdown spectroscopy

    NASA Astrophysics Data System (ADS)

    Aparna, N.; Vasa, Nilesh J.; Sarathi, R.; Rajan, J. Sundara

    2014-10-01

    In recent times, copper sulphide (Cu2S) diffusion in the transformer insulation is a major problem reducing the life of transformers. It is therefore essential to identify a simple methodology to understand the diffusion of Cu2S into the solid insulation [oil impregnated pressboard (OIP)]. In the present work, laser-induced breakdown spectroscopy (LIBS) was adopted to study the diffusion of Cu2S into the pressboard insulation and to determine the depth of diffusion. The diffusion of Cu2S in pressboard was confirmed by electrical discharge studies. In general, flashover voltage and increase in ageing duration of pressboard insulation/Cu concentration had inverse relationship. The characteristic emission lines were also studied through optical emission spectroscopy. Based on LIBS studies with Cu powder dispersed pressboard samples, Cu I emission lines were found to be resolvable up to a lowest concentration of 5 μg/cm2. The LIBS intensity ratio of Cu I-Ca II emission lines were found to increase with increase in the ageing duration of the OIP sample. LIBS studies with OIP samples showed an increase in the optical emission lifetime. LIBS results were in agreement with the electrical discharge studies.

  13. Laser-induced particle size tuning and structural transformations in germanium nanoparticles prepared by stain etching and colloidal synthesis route

    SciTech Connect

    Karatutlu, Ali E-mail: ali.karatutlu@bou.edu.tr; Seker, Isa

    2015-12-28

    In this study, with the aid of Raman measurements, we have observed transformations in small (∼3 nm and ∼10 nm) free-standing Ge nanoparticles under laser light exposure. The nanoparticles were obtained by the chemical stain etching of a monocrystalline Ge wafer and of Ge powder and by colloidal synthesis route. We found that the transformation path depends on laser power and exposure time. At relatively low values of the laser power (2 mW) over a period of 100 min, the Raman signal indicates transformation of the sample from a nanocrystaline to bulk-like state, followed by partial oxidation and finally a conversion of the entire sample into alpha-quartz type GeO{sub 2}. However, when the laser power is set at 60 mW, we observed a heat release during an explosive crystallization of the nanocrystalline material into bulk Ge without noticeable signs of oxidation. Together with the transmission electron microscopy measurements, these results suggest that the chemical stain etching method for the preparation of porous Ge may not be a top-down process as has been widely considered, but a bottom up one. Systematic studies of the laser exposure on Ge nanoparticles prepared by colloidal synthesis results in the fact that the explosive crystallisation is common for H-terminated and partially disordered Ge nanoparticles regardless of its particle size. We suggest possible bio-medical applications for the observed phenomena.

  14. Laser-induced particle size tuning and structural transformations in germanium nanoparticles prepared by stain etching and colloidal synthesis route

    NASA Astrophysics Data System (ADS)

    Karatutlu, Ali; Little, William; Ersoy, Osman; Zhang, Yuanpeng; Seker, Isa; Sapelkin, Andrei

    2015-12-01

    In this study, with the aid of Raman measurements, we have observed transformations in small (˜3 nm and ˜10 nm) free-standing Ge nanoparticles under laser light exposure. The nanoparticles were obtained by the chemical stain etching of a monocrystalline Ge wafer and of Ge powder and by colloidal synthesis route. We found that the transformation path depends on laser power and exposure time. At relatively low values of the laser power (2 mW) over a period of 100 min, the Raman signal indicates transformation of the sample from a nanocrystaline to bulk-like state, followed by partial oxidation and finally a conversion of the entire sample into alpha-quartz type GeO2. However, when the laser power is set at 60 mW, we observed a heat release during an explosive crystallization of the nanocrystalline material into bulk Ge without noticeable signs of oxidation. Together with the transmission electron microscopy measurements, these results suggest that the chemical stain etching method for the preparation of porous Ge may not be a top-down process as has been widely considered, but a bottom up one. Systematic studies of the laser exposure on Ge nanoparticles prepared by colloidal synthesis results in the fact that the explosive crystallisation is common for H-terminated and partially disordered Ge nanoparticles regardless of its particle size. We suggest possible bio-medical applications for the observed phenomena.

  15. Narrow-band resonant optical reflectors and resonant optical transformers for laser stabilization and wavelength division multiplexing

    SciTech Connect

    Kazarinov, R.F.; Henry, C.H.; Olsson, N.A.

    1987-09-01

    The authors propose a new way of making highly resonant integrated optical circuits based on weak side-by-side coupling between waveguides and high Q distributed Bragg resonators. This method can be used to design a resonant optical reflector which, when used as a feedback element to a laser, will result in a compact structure that has both extremely narrow line width and very low chirp. By coupling the resonator to two waveguides, one on either side, an optical analog of the resonant transformer can be made. This device can be used for wavelength division multiplexing. Such multiplexer elements will both resonantly transform optical power from the laser to a common output channel and also provide feedback which locks the laser to the channel wavelength.

  16. Conjugation and transformation of the wave front by stimulated Brillouin scattering of vortex Laguerre - Gaussian laser modes

    SciTech Connect

    Kopalkin, A V; Bogachev, V A; Dolgopolov, Yu V; Kochemasov, G G; Kulikov, S M; Maslov, N V; Starikov, F A; Sukharev, Stanislav A; Feoktistov, V V; Bagdasarov, V Kh; Denisov, N N; Malyutin, A A

    2011-11-30

    We study experimentally stimulated Brilluoin scattering (SBS) of vortex laser beams, namely, the LG{sub 1}{sup 1} and LG{sub 0}{sup 1} Laguerre -Gaussian modes. The wave front transformation is experimentally demonstrated in the case of SBS of the LG{sub 1}{sup 1} laser mode, directly focused into the SBS cell, when the fundamental Gaussian mode LG{sub 0}{sup 0} rather than the conjugate mode is selected from the Stokes beam. It is shown that optical vortices become phase conjugate by destroying the laser mode structure in the SBS cell. Phase conjugation (PC) of the LG{sub 0}{sup 1} and LG{sub 1}{sup 1} modes is obtained in the SBS mirror using a regular aberrator (microlens raster) in the system of laser beam focusing into the SBS cell.

  17. Life on the Hardened Border

    ERIC Educational Resources Information Center

    Miller, Bruce Granville

    2012-01-01

    The many Coast Salish groups distributed on both sides of the United States-Canada border on the Pacific coast today face significant obstacles to cross the international border, and in some cases are denied passage or intimidated into not attempting to cross. The current situation regarding travel by Aboriginal people reflects the "hardening" of…

  18. Onycholysis induced by nail hardener.

    PubMed

    Helsing, Per; Austad, Joar; Talberg, Hans Jørgen

    2007-10-01

    Nail hardeners appeared in the market during the 1960s. They were basically solutions of formaldehyde. The first adverse effects were published in 1966 (1). Reactions were onycholysis, chromonychia, subungual haemorrhage, and hyperkeratosis. Onycholysis may be non-inflammatory or inflammatory, and is accompanied by throbbing pain. Inflammatory reactions are followed by paronychia and occasional dermatitis on the digital pulpa. PMID:17868227

  19. Laser vision: lidar as a transformative tool to advance critical zone science

    NASA Astrophysics Data System (ADS)

    Harpold, A. A.; Marshall, J. A.; Lyon, S. W.; Barnhart, T. B.; Fisher, B.; Donovan, M.; Brubaker, K. M.; Crosby, C. J.; Glenn, N. F.; Glennie, C. L.; Kirchner, P. B.; Lam, N.; Mankoff, K. D.; McCreight, J. L.; Molotch, N. P.; Musselman, K. N.; Pelletier, J.; Russo, T.; Sangireddy, H.; Sjöberg, Y.; Swetnam, T.; West, N.

    2015-01-01

    Laser vision: lidar as a transformative tool to advance critical zone science. Observation and quantification of the Earth surface is undergoing a revolutionary change due to the increased spatial resolution and extent afforded by light detection and ranging (lidar) technology. As a consequence, lidar-derived information has led to fundamental discoveries within the individual disciplines of geomorphology, hydrology, and ecology. These disciplines form the cornerstones of Critical Zone (CZ) science, where researchers study how interactions among the geosphere, hydrosphere, and ecosphere shape and maintain the "zone of life", extending from the groundwater to the vegetation canopy. Lidar holds promise as a transdisciplinary CZ research tool by simultaneously allowing for quantification of topographic, vegetative, and hydrological data. Researchers are just beginning to utilize lidar datasets to answer synergistic questions in CZ science, such as how landforms and soils develop in space and time as a function of the local climate, biota, hydrologic properties, and lithology. This review's objective is to demonstrate the transformative potential of lidar by critically assessing both challenges and opportunities for transdisciplinary lidar applications. A review of 147 peer-reviewed studies utilizing lidar showed that 38 % of the studies were focused in geomorphology, 18 % in hydrology, 32 % in ecology, and the remaining 12 % have an interdisciplinary focus. We find that using lidar to its full potential will require numerous advances across CZ applications, including new and more powerful open-source processing tools, exploiting new lidar acquisition technologies, and improved integration with physically-based models and complementary in situ and remote-sensing observations. We provide a five-year vision to utilize and advocate for the expanded use of lidar datasets to benefit CZ science applications.

  20. The origins of pressure-induced phase transformations during the surface texturing of silicon using femtosecond laser irradiation

    NASA Astrophysics Data System (ADS)

    Smith, Matthew J.; Sher, Meng-Ju; Franta, Benjamin; Lin, Yu-Ting; Mazur, Eric; Gradečak, Silvija

    2012-10-01

    Surface texturing of silicon using femtosecond (fs) laser irradiation is an attractive method for enhancing light trapping, but the laser-induced damage that occurs in parallel with surface texturing can inhibit device performance. In this work, we investigate the light-material interaction during the texturing of silicon by directly correlating the formation of pressure-induced silicon polymorphs, fs-laser irradiation conditions, and the resulting morphology and microstructure using scanning electron microscopy, micro-Raman spectroscopy, and transmission electron microscopy. We show that raster scanning a pulsed laser beam with a Gaussian profile enhances the formation of crystalline pressure-induced silicon polymorphs by an order of magnitude compared with stationary pulsed fs-laser irradiation. Based on these observations, we identify resolidification-induced stresses as the mechanism responsible for driving sub-surface phase transformations during the surface texturing of silicon, the understanding of which is an important first step towards reducing laser-induced damage during the texturing of silicon with fs-laser irradiation.

  1. Quantitative characterization of the surface topography of rolled sheets by laser scanning microscopy and fourier transformation

    NASA Astrophysics Data System (ADS)

    Gjønnes, Liv

    1996-08-01

    The surface of twin-roll cast aluminum sheets undergoes dramatic changes during cold rolling. This is mainly due to variables in the roll gap, topography of the rolls, lubrication, material properties, and in particular the initial structure and topography of the cast sheet. Therefore, it is important to have means to quantitatively describe the changes in the surface structure of each pass and from pass to pass in order to optimize the desired final surface structure. To achieve this, the laser scanning microscope (LSM) with its confocal technique has been employed to image the three-dimensional (3-D) topography and to digitize the image for further computer analysis. The digitization of the image is primarily motivated by the need to introduce a Fourier transformation of the surface topography. The method is effective in describing qualitative periodic trends in the surface features. Information is gained on the shape and periodicities as well as roughness directionality. For instance, grooves and cross hatches and their remnants can be followed from one pass to the other. Important characteristics of the surface topography such as rolling ridges and shingles can also easily be characterized.

  2. Physiological effects of indomethacin and celecobix: an S-transform laser Doppler flowmetry signal analysis

    NASA Astrophysics Data System (ADS)

    Assous, S.; Humeau, A.; Tartas, M.; Abraham, P.; L'Huillier, J. P.

    2005-05-01

    Conventional signal processing typically involves frequency selective techniques which are highly inadequate for nonstationary signals. In this paper, we present an approach to perform time-frequency selective processing of laser Doppler flowmetry (LDF) signals using the S-transform. The approach is motivated by the excellent localization, in both time and frequency, afforded by the wavelet basis functions. Suitably chosen Gaussian wavelet functions are used to characterize the subspace of signals that have a given localized time-frequency support, thus enabling a time-frequency partitioning of signals. In this paper, the goal is to study the influence of various pharmacological substances taken by the oral way (celecobix (Celebrex®), indomethacin (Indocid®) and placebo) on the physiological activity behaviour. The results show that no statistical differences are observed in the energy computed from the time-frequency representation of LDF signals, for the myogenic, neurogenic and endothelial related metabolic activities between Celebrex and placebo, and Indocid and placebo. The work therefore proves that these drugs do not affect these physiological activities. For future physiological studies, there will therefore be no need to exclude patients having taken cyclo-oxygenase 1 inhibitions.

  3. Mechanism and technological particular features of thermomagnetic hardening

    NASA Astrophysics Data System (ADS)

    Borovskij, S. M.; Mukhin, V. S.

    1993-10-01

    The particular features of mechanism associated with piece hardening of gas-turbine engines are analyzed. This mechanism is connected with the change of conditions for phase equilibrium and kinetics of transformations. It is important to estimate the nature of the formation of new ferromagnetic centers at phase transitions, when permanent, pulsed, or periodic magnetic fields act. Two factors should be taken into account: the power effect of the magnetic field and the increase of 'magnetic segregation' of a source nonferromagnetic matrix.

  4. Freeform beam shaping for high-power multimode lasers

    NASA Astrophysics Data System (ADS)

    Laskin, Alexander; Laskin, Vadim

    2014-03-01

    Widening of using high power multimode lasers in industrial laser material processing is accompanied by special requirements to irradiance profiles in such technologies like metal or plastics welding, cladding, hardening, brazing, annealing, laser pumping and amplification in MOPA lasers. Typical irradiance distribution of high power multimode lasers: free space solid state, fiber-coupled solid state and diodes lasers, fiber lasers, is similar to Gaussian. Laser technologies can be essentially improved when irradiance distribution on a workpiece is uniform (flattop) or inverse-Gauss; when building high-power pulsed lasers it is possible to enhance efficiency of pumping and amplification by applying super-Gauss irradiance distribution with controlled convexity. Therefore, "freeform" beam shaping of multimode laser beams is an important task. A proved solution is refractive field mapping beam shaper like Shaper capable to control resulting irradiance profile - with the same unit it is possible to get various beam profiles and choose optimum one for a particular application. Operational principle of these devices implies transformation of laser irradiance distribution by conserving beam consistency, high transmittance, providing collimated low divergent output beam. Using additional optics makes it possible to create resulting laser spots of necessary size and round, elliptical or linear shape. Operation out of focal plane and, hence, in field of lower wavefront curvature, allows extending depth of field. The refractive beam shapers are implemented as telescopes and collimating systems, which can be connected directly to fiber-coupled lasers or fiber lasers, thus combining functions of beam collimation and irradiance transformation.

  5. Hadamard transform microchip electrophoresis combined with laser-induced fluorescence detection using a compact neodymium-doped yttrium aluminum garnet laser emitting at 532 nm

    NASA Astrophysics Data System (ADS)

    Hata, Kazuki; Kaneta, Takashi; Imasaka, Totaro

    2009-05-01

    Hadamard transform electrophoresis combined with laser-induced fluorescence (LIF) detection on a microchip was demonstrated. A compact, diode-pumped neodymium-doped yttrium aluminum garnet laser was employed as the light source for LIF detection. The analytical conditions were optimized using rhodamine B as the analyte. Under optimal conditions, the signal-to-noise ratio (S/N) of the analyte was improved by a factor of 7.5 by means of Hadamard transformation based on a 255-order cyclic S matrix. Additionally, the relationship between fluorescence intensity and analyte concentration was linear with a correlation coefficient of 0.993 in the inverse Hadamard transformed data at the concentration range from 25 to 100 pM. The results indicate that the present method is applicable to quantitative analysis at the concentration lower than the concentration limit of detection in a conventional method. The concentration limit of detection was ˜25 pM (the relative standard deviation of the peak height was 5.2%). The present technique was successfully applied to the separation of a mixture containing 1.9 nM phenylalanine and 1.9 nM glutamic acid labeled with rhodamine B isothiocyanate. The S/Ns of the analyte peaks were improved up to ˜10 in the inverse Hadamard transformed data derived from a 127-order cyclic S matrix, while neither peak was lower than the limit of detection (S/N<3) in conventional microchip electrophoresis by a single injection.

  6. Scintillation-Hardened GPS Receiver

    NASA Technical Reports Server (NTRS)

    Stephens, Donald R.

    2015-01-01

    CommLargo, Inc., has developed a scintillation-hardened Global Positioning System (GPS) receiver that improves reliability for low-orbit missions and complies with NASA's Space Telecommunications Radio System (STRS) architecture standards. A software-defined radio (SDR) implementation allows a single hardware element to function as either a conventional radio or as a GPS receiver, providing backup and redundancy for platforms such as the International Space Station (ISS) and high-value remote sensing platforms. The innovation's flexible SDR implementation reduces cost, weight, and power requirements. Scintillation hardening improves mission reliability and variability. In Phase I, CommLargo refactored an open-source GPS software package with Kalman filter-based tracking loops to improve performance during scintillation and also demonstrated improved navigation during a geomagnetic storm. In Phase II, the company generated a new field-programmable gate array (FPGA)-based GPS waveform to demonstrate on NASA's Space Communication and Navigation (SCaN) test bed.

  7. Surface Fatigue Resistance with Induction Hardening

    NASA Technical Reports Server (NTRS)

    Townsend, Dennis; Turza, Alan; Chapman, Mike

    1996-01-01

    Induction hardening has been used for some years to harden the surface and improve the strength and service life of gears and other components. Many applications that employ induction hardening require a relatively long time to finish the hardening process and controlling the hardness of the surface layer and its depth often was a problem. Other surface hardening methods, ie., carbonizing, take a very long time and tend to cause deformations of the toothing, whose elimination requires supplementary finishing work. In double-frequency induction hardening, one uses a low frequency for the preheating of the toothed wheel and a much higher frequency for the purpose of rapidly heating the surface by way of surface hardening.

  8. Laser and electrical current induced phase transformation of In2Se3 semiconductor thin film on Si(111)

    NASA Astrophysics Data System (ADS)

    Lu, Chih-Yuan; Shamberger, Patrick J.; Yitamben, Esmeralda N.; Beck, Kenneth M.; Joly, Alan G.; Olmstead, Marjorie A.; Ohuchi, Fumio S.

    2008-10-01

    Phase transformation of thin film (˜30 nm)In2Se3/Si(111) (amorphous→crystalline) was performed by resistive annealing and the reverse transformation (crystalline→amorphous) was performed by nanosecond laser annealing. As an intrinsic-vacancy, binary chalcogenide semiconductor, In2Se3 is of interest for non-volatile phase-change memory. Amorphous In x Se y was deposited at room temperature on Si(111) after pre-deposition of a crystalline In2Se3 buffer layer (0.64 nm). Upon resistive annealing to 380°C, the film was transformed into a γ-In2Se3 single crystal with its {0001} planes parallel to the Si(111) substrate and (11bar{2}0) parallel to Si (1bar{1}0) , as evidenced by scanning tunneling microscopy, low energy electron diffraction, and X-ray diffraction. Laser annealing with 20-ns pulses (0.1 millijoules/pulse, fluence≤50 mJ/cm2) re-amorphized the region exposed to the laser beam, as observed with photoemission electron microscopy (PEEM). The amorphous phase in PEEM appears dark, likely due to abundant defect levels inhibiting electron emission from the amorphous In x Se y film.

  9. Fourier transform-limited optical frequency-modulated continuous-wave interferometry over several tens of laser coherence lengths.

    PubMed

    Xie, Weilin; Zhou, Qian; Bretenaker, Fabien; Xia, Zongyang; Shi, Hongxiao; Qin, Jie; Dong, Yi; Hu, Weisheng

    2016-07-01

    We report on a versatile optical frequency-modulated continuous-wave interferometry technique that exploits wideband phase locking for generating highly coherent linear laser frequency chirps. This technique is based on an ultra-short delay-unbalanced interferometer, which leads to a large bandwidth, short lock time, and robust operation even in the absence of any isolation from environmental perturbations. In combination with a digital delay-matched phase error compensation, this permits the achievement of a range window about 60 times larger than the intrinsic laser coherence length with a 1.25 mm Fourier transform-limited spatial resolution. The demonstrated configuration can be easily applied to virtually any semiconductor laser. PMID:27367076

  10. [Accuracy Improvement of Temperature Calculation of the Laser-Induced Plasma Using Wavelet Transform Baseline Subtraction].

    PubMed

    Liu, Li; Xiao, Ping-ping

    2016-02-01

    Temperature is one of the most important parameters in studying of laser-induced plasma characteristics. To reduce the impact of continuous background on the calculation of temperatures using Boltzmann plots, the wavelet transform was used to decompose the spectrums, and the low-frequency signals represented the spectral baseline were deducted by using soft-threshold method. Selecting the appropriate wavelet decomposition level L and threshold coefficient a can increase the linear regression coefficient R2 of Boltzmann plots, and the calculation accuracy of plasma temperature was improved. The LIBS spectra of low alloy steel sample region from 417 to 445 nm were decomposed by using db4 wavelet, and then baseline subtraction and signal reconstruction were carried out, respectively. Twelve Fe atomic lines were chosen to establish Boltzmann plots, and the temperatures were calculated from the slope of the fitted lines in the plots. The value L and a were optimized according R², the results showed that the 8-layer db4 wavelet decomposition can gain the high R², while the value of a associated with the delay time td, e. g. , the optimum a corresponding to maximum values of R² is 0.3 when td ≤ 4.0 µs, and then decrease with the increasing of td, and reduced to 0 when td ≥ 6. 0 µs. The interference due to baseline on the spectral characteristic lines gradually reduced with the increasing of td, and therefore a decreased with td increase. After the baseline was deducted, the temperature calculated by Boltzmann plot decrease of about 2 000 to 3 000 K. The temperature gradually decreased with the increasing of the td, and the temperature fluctuation is reduced after baseline subtraction, these results are consistent with the physical process of plasma expansion. PMID:27209766

  11. Surface-Induced Dissociation of Ions Produced by Matrix-Assisted Laser Desorption Ionization in a Fourier Transform Ion Cyclotron Resonance Mass Spectrometer

    SciTech Connect

    Laskin, Julia; Beck, Kenneth M.; Hache, John J.; Futrell, Jean H.

    2004-01-15

    Intermediate pressure matrix assisted laser ionization (MALDI) source was constructed and interfaced with a 6T Fourier transform ion cyclotron resonance mass spectrometer (FT-ICR MS) specially configured for surface-induced dissociation (SID) studies.

  12. Jarosite as a Storage Mineral for Small Organic Molecules: Investigations of Natural Samples Using an 'In Situ' Laser Desorption Fourier Transform Mass Spectrometry Technique

    NASA Astrophysics Data System (ADS)

    Kotler, J. M.; Hinman, N. W.; Yan, B.; Stoner, D. L.; Scott, J. R.

    2007-03-01

    The use of laser desorption Fourier transform mass spectrometry has revealed the presence of organic matter in several jarosite samples from various locations worldwide including jarosite precipitated in the lab by acidothiobacillus ferroxidans.

  13. Temporal-space-transforming pulse-shaping system with a knife-edge apparatus for a high-energy laser facility

    NASA Astrophysics Data System (ADS)

    Shen, Lei; Chen, Shaohe; Ge, Xiaping; Xu, Shizhong; Fan, Dianyuan

    2005-09-01

    For the first time to our knowledge, in a high-energy laser facility with an output energy of 454.37 J, by using a temporal-space-transforming pulse-shaping system with our own design of a knife-edge apparatus, we obtained a quasi-square laser pulse.

  14. DISPERSION HARDENING OF URANIUM METAL

    DOEpatents

    Arbiter, W.

    1963-01-15

    A method of hardening U metal involves the forming of a fine dispersion of UO/sub 2/. This method consists of first hydriding the U to form a finely divided powder and then exposing the powder to a very dilute O gas in an inert atmosphere under such pressure and temperature conditions as to cause a thin oxide film to coat each particle of the U hydride, The oxide skin prevents agglomeration of the particles as the remaining H is removed, thus preserving the small particle size. The oxide skin coatings remain as an oxide dispersion. The resulting product may be workhardened to improve its physical characteristics. (AEC)

  15. An Abel transform for deriving line-of-sight wind profiles from LEO-LEO infrared laser occultation measurements

    NASA Astrophysics Data System (ADS)

    Syndergaard, S.; Kirchengast, G.

    2016-03-01

    We have developed a formula for the retrieval of the line-of-sight (l.o.s.) wind speed from future low Earth orbit (LEO) satellite-to-satellite infrared laser occultation measurements. The formula involves an Abelian integral transform akin to the Abel transform widely used for deriving refractive index from bending angle in Global Navigation Satellite System radio occultation measurements. Besides the Abelian integral transform, the formula is derived from a truncated series expansion of the volume absorption coefficient as a function of frequency and includes a simple absorption-line-asymmetry correction term. A first-order formulation (referred to as the standard formula) is complemented by higher-order terms that can be used for high-accuracy computations. Under the assumptions of spherical symmetry and perfect knowledge of spectroscopy, the residual l.o.s. wind error from using the standard formula rather than the high-accuracy formula is assessed to be small compared to that anticipated from measurement errors in a real experiment. Applying the new formula just in standard form to future infrared laser transmission profiles would therefore enable the retrieval of l.o.s. stratospheric wind profiles with an accuracy limited mainly by measurement errors, residual spectroscopic errors, and deviations from spherical symmetry.

  16. Practical aspects of registration the transformation of a river valley by beavers using terrestrial laser scanning

    NASA Astrophysics Data System (ADS)

    Tyszkowski, Sebastian; Błaszkiewicz, Mirosław; Brykała, Dariusz; Gierszewski, Piotr; Kaczmarek, Halina; Kordowski, Jarosław; Słowiński, Michał

    2016-04-01

    Activity of beavers (Castor fiber) often significantly affects the environment in which they life. The most commonly observed effect of their being in environment is construction of beaver dams and formation a pond upstream. However, in case of a sudden break of a dam and beaver pond drainage, the valley below the dam may also undergo remodelling. The nature and magnitude of these changes depends on the quantity of water and its energy as well as on the geological structure of the valley. The effects of such events can be riverbank erosion, and the deposition of the displaced of erosion products in the form of sandbars or fans. The material can also be accumulated in local depressions or delivered to water bodies. Such events may occur multiple times in the same area. To assess their impact on the environment it is important to quantify the displaced material. The study of such transformations was performed within a small valley of the river of Struga Czechowska (Tuchola Pinewood Forest, Poland). The valley is mainly cut in sands and gravels. Its steep banks are overgrown with bushes and trees. The assessment of changes in morphology were based on the event of the beaver pond drainage of 2015. The study uses the measurements from the terrestrial laser scanning (scanner Riegl VZ-4000). The measurements were performed before and after the event. Each of the two models obtained for comparison was made up of more than 20 measurement stations. Point clouds were joined by Multi-Station Adjustment without placing in the terrain any objects of reference. During measurements attention was paid to the changes in morphology of both riverbed and valley surrounding. The paper presents the example of the recorded changes as well as the measurement procedure. Moreover, the aspects of fieldwork and issues related to post-processing, such as merging, filtering of point clouds and detection of changes, are also presented. This study is a contribution to the Virtual Institute of

  17. Stress and Distortion Evolution During Induction Case Hardening of Tube

    NASA Astrophysics Data System (ADS)

    Nemkov, Valentin; Goldstein, Robert; Jackowski, John; Ferguson, Lynn; Li, Zhichao

    2013-07-01

    Simulation of stresses during heat treatment relates usually to furnace heating. Induction heating provides a very different evolution of temperature in the part and therefore different stresses. This may be positive for service properties or negative, reducing component strength or even causing cracks. A method of coupled simulation between electromagnetic, thermal, structural, stress, and deformation phenomena during induction tube hardening is described. Commercial software package ELTA is used to calculate the power density distribution in the load resulting from the induction heating process. The program DANTE is used to predict temperature distribution, phase transformations, stress state, and deformation during heating and quenching. Analyses of stress and deformation evolution were made on a simple case of induction hardening of external (1st case) and internal (2nd case) surfaces of a thick-walled tubular body.

  18. Energy-Efficient Thermomagnetic and Induction Hardening

    SciTech Connect

    2009-02-01

    This factsheet describes a research project that will develop and test a hybrid thermomagnetic and induction hardening technology to replace conventional heat treatment processes in forging applications.

  19. Radiation Hardened Electronics for Extreme Environments

    NASA Technical Reports Server (NTRS)

    Keys, Andrew S.; Watson, Michael D.

    2007-01-01

    The Radiation Hardened Electronics for Space Environments (RHESE) project consists of a series of tasks designed to develop and mature a broad spectrum of radiation hardened and low temperature electronics technologies. Three approaches are being taken to address radiation hardening: improved material hardness, design techniques to improve radiation tolerance, and software methods to improve radiation tolerance. Within these approaches various technology products are being addressed including Field Programmable Gate Arrays (FPGA), Field Programmable Analog Arrays (FPAA), MEMS Serial Processors, Reconfigurable Processors, and Parallel Processors. In addition to radiation hardening, low temperature extremes are addressed with a focus on material and design approaches.

  20. Lasers.

    ERIC Educational Resources Information Center

    Schewe, Phillip F.

    1981-01-01

    Examines the nature of laser light. Topics include: (1) production and characteristics of laser light; (2) nine types of lasers; (3) five laser techniques including holography; (4) laser spectroscopy; and (5) laser fusion and other applications. (SK)

  1. COSMIC-RAY HELIUM HARDENING

    SciTech Connect

    Ohira, Yutaka; Ioka, Kunihito

    2011-03-01

    Recent observations by the CREAM and ATIC-2 experiments suggest that (1) the spectrum of cosmic-ray (CR) helium is harder than that of CR protons below the knee energy, 10{sup 15}eV, and (2) all CR spectra become hard at {approx}>10{sup 11}eV nucleon{sup -1}. We propose a new idea, that higher energy CRs are generated in a more helium-rich region, to explain the hardening without introducing different sources for CR helium. The helium-to-proton ratio at {approx}100 TeV exceeds the Big Bang abundance Y = 0.25 by several times, and the different spectrum is not reproduced within the diffusive shock acceleration theory. We argue that CRs are produced in a chemically enriched region, such as a superbubble, and the outward-decreasing abundance naturally leads to the hard spectrum of CR helium if CRs escape from the supernova remnant shock in an energy-dependent way. We provide a simple analytical spectrum that also fits well the hardening due to the decreasing Mach number in the hot superbubble with {approx}10{sup 6} K. Our model predicts hard and concave spectra for heavier CR elements.

  2. Low-level laser therapy on MCF-7 cells: a micro-Fourier transform infrared spectroscopy study

    NASA Astrophysics Data System (ADS)

    Magrini, Taciana D.; dos Santos, Nathalia Villa; Milazzotto, Marcella Pecora; Cerchiaro, Giselle; da Silva Martinho, Herculano

    2012-10-01

    Low-level laser therapy (LLLT) is an emerging therapeutic approach for several clinical conditions. The clinical effects induced by LLLT presumably scale from photobiostimulation/photobioinhibition at the cellular level to the molecular level. The detailed mechanism underlying this effect remains unknown. This study quantifies some relevant aspects of LLLT related to molecular and cellular variations. Malignant breast cells (MCF-7) were exposed to spatially filtered light from a He-Ne laser (633 nm) with fluences of 5, 28.8, and 1000 mJ/cm2. The cell viability was evaluated by optical microscopy using the Trypan Blue viability test. The micro-Fourier transform infrared technique was employed to obtain the vibrational spectra of each experimental group (control and irradiated) and identify the relevant biochemical alterations that occurred due to the process. It was observed that the red light influenced the RNA, phosphate, and serine/threonine/tyrosine bands. We found that light can influence cell metabolism depending on the laser fluence. For 5 mJ/cm2, MCF-7 cells suffer bioinhibition with decreased metabolic rates. In contrast, for the 1 J/cm2 laser fluence, cells present biostimulation accompanied by a metabolic rate elevation. Surprisingly, at the intermediate fluence, 28.8 mJ/cm2, the metabolic rate is increased despite the absence of proliferative results. The data were interpreted within the retrograde signaling pathway mechanism activated with light irradiation.

  3. Effects of Er:YAG laser irradiation and manipulation treatments on dentin components, part 1: Fourier transform-Raman study

    NASA Astrophysics Data System (ADS)

    Soares, Luís Eduardo Silva; Do Espírito Santo, Ana Maria; Junior, Aldo Brugnera; Zanin, Fátima Antônia Aparecida; da Silva Carvalho, Carolina; de Oliveira, Rodrigo; Martin, Airton Abraha~O.

    2009-03-01

    The effects of laser etching, decontamination, and storage treatments on dentin components were studied using Fourier transform (FT)-Raman spectroscopy. Thirty bovine incisors were prepared to expose the dentin surface and then divided in two main groups based upon the decontamination process and storage procedure: autoclaved (group A, n=15) or stored in thymol aqueous solution (group B, n=15). The surfaces of the dentin slices were schematically divided into four areas, with each one corresponding to a treatment subgroup. The specimens were either etched with phosphoric acid (control subgroup) or irradiated with erbium-doped yttrium-aluminum-garnet (Er:YAG) laser (subgroups: I-80 mJ, II-120 mJ, and III-180 mJ, and total energy of 12 J). Samples were analyzed by FT-Raman spectroscopy; we collected three spectra for each area (before and after treatment). The integrated areas of five Raman peaks were calculated to yield average spectra. The areas of the peaks associated with phosphate content (P<0.001), type I collagen, and organic C-H bonds (P<0.05) were reduced significantly in group A (control). Analyses of samples irradiated with reduced laser energies did not show significant changes in the dentin components. These results suggest that thymol storage treatment is advised for in vitro study; furthermore, 12 J of Er:YAG laser energy does not affect dentin components.

  4. Accessing Extreme Spatiotemporal Localization of High-Power Laser Radiation through Transformation Optics and Scalar Wave Equations

    NASA Astrophysics Data System (ADS)

    Fedorov, V. Yu.; Chanal, M.; Grojo, D.; Tzortzakis, S.

    2016-07-01

    Although tightly focused intense ultrashort laser pulses are used in many applications from nano-processing to warm dense matter physics, their nonparaxial propagation implies the use of numerical simulations with vectorial wave equations or exact Maxwell solvers that have serious limitations and thus have hindered progress in this important field up to now. Here we present an elegant and robust solution that allows one to map the problem on one that can be addressed by simple scalar wave equations. The solution is based on a transformation optics approach and its validity is demonstrated in both the linear and the nonlinear regime. Our solution allows accessing challenging problems of extreme spatiotemporal localization of high power laser radiation that remain almost unexplored theoretically until now.

  5. Accessing Extreme Spatiotemporal Localization of High-Power Laser Radiation through Transformation Optics and Scalar Wave Equations.

    PubMed

    Fedorov, V Yu; Chanal, M; Grojo, D; Tzortzakis, S

    2016-07-22

    Although tightly focused intense ultrashort laser pulses are used in many applications from nano-processing to warm dense matter physics, their nonparaxial propagation implies the use of numerical simulations with vectorial wave equations or exact Maxwell solvers that have serious limitations and thus have hindered progress in this important field up to now. Here we present an elegant and robust solution that allows one to map the problem on one that can be addressed by simple scalar wave equations. The solution is based on a transformation optics approach and its validity is demonstrated in both the linear and the nonlinear regime. Our solution allows accessing challenging problems of extreme spatiotemporal localization of high power laser radiation that remain almost unexplored theoretically until now. PMID:27494473

  6. Structural transformation and residual stresses in surface layers of α + β titanium alloys nanotextured by femtosecond laser pulses

    NASA Astrophysics Data System (ADS)

    Kolobov, Yu. R.; Golosov, E. V.; Vershinina, T. N.; Zhidkov, M. V.; Ionin, A. A.; Kudryashov, S. I.; Makarov, S. V.; Seleznev, L. V.; Sinitsyn, D. V.; Ligachev, A. E.

    2015-04-01

    Surface topography, phase composition and compressive residual stresses were characterized in surface layers of α + β titanium alloys VT6 (Ti-6Al-4V) and VT16 (Ti-3Al-4.5V-5Mo) nanotextured by 744-nm, 120-fs-laser pulses. The relative content of β-phase, along with the residual compressive stresses, increases significantly in both these materials over the depth ~0.2 μ in the nanotextured surface layer comprised by nanograins and remains almost unchanged at higher depths of 1-2 μ in bulk. The laser-driven α → β phase transformation is related to the combined effect of ultrafast heating/cooling, strong (multi-GPa) shock waves, chemical segregation and nanograin formation induced during the ablative surface nanotexturing.

  7. Reference Interferometer Using a Semiconductor Laser/LED Reference Source in a Cryogenic Fourier-Transform Spectrometer

    NASA Technical Reports Server (NTRS)

    Martino, Anthony J.; Cornwell, Donald M.

    1998-01-01

    A combination of a single mode AlGaAs laser diode and broadband LED was used in a Michelson interferometer to provide reference signals in a Fourier transform spectrometer, the Composite Infrared Spectrometer, on the Cassini mission to Saturn. The narrowband light from the laser produced continuous fringes throughout the travel of the interferometer, which were used to control the velocity of the scan mechanism and to trigger data sampling. The broadband light from the LED produced a burst of fringes at zero path difference, which was used as a fixed position reference. The system, including the sources, the interferometer, and the detectors, was designed to work both at room temperature and instrument operating temperature of 170 Kelvin. One major challenge that was overcome was preservation, from room temperature to 170 K, of alignment sufficient for high modulation of fringes from the broadband source. Another was the shift of the source spectra about 30 nm toward shorter wavelengths upon cooldown.

  8. Analysis of structure and phase composition of rails subjected to differential hardening at different regimes

    SciTech Connect

    Gromov, V. E. Morozov, K. V. Konovalov, S. V.; Alsaraeva, K. V.; Semina, O. A.; Ivanov, Yu. F.; Volkov, K. V.

    2014-11-14

    Differential hardening of rails by compressed air in different regimes is accompanied by formation of morphologically different structure, being formed according to the diffusion mechanism of γ↔α transformation and consisting of grains of lamellar pearlite, free ferrite and grains of ferrite-carbide mixture. By methods of transmission electron microscopy the layer by layer analysis of differentially hardened rails has been carried out, the quantitative parameters of the structure, phase composition and dislocation substructure have been established and their comparison has been made for different regimes of hardening. It has been found that the structure-phase states being formed have gradient character, defined by the hardening regime, direction of study from the surface of rolling and by depth of location of layer under study.

  9. An Investigation of the Massive Transformation from Ferrite to Austenite in Laser-Welded Mo-Bearing Stainless Steels

    NASA Astrophysics Data System (ADS)

    Perricone, M. J.; Dupont, J. N.; Anderson, T. D.; Robino, C. V.; Michael, J. R.

    2011-03-01

    A series of 31 Mo-bearing stainless steel compositions with Mo contents ranging from 0 to 10 wt pct and exhibiting primary δ-ferrite solidification were analyzed over a range of laser welding conditions to evaluate the effect of composition and cooling rate on the solid-state transformation to γ-austenite. Alloys exhibiting this microstructural development sequence are of particular interest to the welding community because of their reduced susceptibility to solidification cracking and the potential reduction of microsegregation (which can affect corrosion resistance), all while harnessing the high toughness of γ-austenite. Alloys were created using the arc button melting process, and laser welds were prepared on each alloy at constant power and travel speeds ranging from 4.2 to 42 mm/s. The cooling rates of these processes were estimated to range from 10 K (°C)/s for arc buttons to 105 K (°C)/s for the fastest laser welds. No shift in solidification mode from primary δ-ferrite to primary γ-austenite was observed in the range of compositions or welding conditions studied. Metastable microstructural features were observed in many laser weld fusion zones, as well as a massive transformation from δ-ferrite to γ-austenite. Evidence of epitaxial massive growth without nucleation was also found when intercellular γ-austenite was already present from a solidification reaction. The resulting single-phase γ-austenite in both cases exhibited a homogenous distribution of Mo, Cr, Ni, and Fe at nominal levels.

  10. A new time-frequency method to reveal quantum dynamics of atomic hydrogen in intense laser pulses: Synchrosqueezing transform

    SciTech Connect

    Sheu, Yae-lin; Hsu, Liang-Yan; Wu, Hau-tieng; Li, Peng-Cheng; Chu, Shih-I

    2014-11-15

    This study introduces a new adaptive time-frequency (TF) analysis technique, the synchrosqueezing transform (SST), to explore the dynamics of a laser-driven hydrogen atom at an ab initio level, upon which we have demonstrated its versatility as a new viable venue for further exploring quantum dynamics. For a signal composed of oscillatory components which can be characterized by instantaneous frequency, the SST enables rendering the decomposed signal based on the phase information inherited in the linear TF representation with mathematical support. Compared with the classical type of TF methods, the SST clearly depicts several intrinsic quantum dynamical processes such as selection rules, AC Stark effects, and high harmonic generation.

  11. Radially and azimuthally polarized laser induced shape transformation of embedded metallic nanoparticles in glass.

    PubMed

    Tyrk, Mateusz A; Zolotovskaya, Svetlana A; Gillespie, W Allan; Abdolvand, Amin

    2015-09-01

    Radially and azimuthally polarized picosecond (~10 ps) pulsed laser irradiation at 532 nm wavelength led to the permanent reshaping of spherical silver nanoparticles (~30 - 40 nm in diameter) embedded in a thin layer of soda-lime glass. The observed peculiar shape modifications consist of a number of different orientations of nano-ellipsoids in the cross-section of each written line by laser. A Second Harmonic Generation cross-sectional scan method from silver nanoparticles in transmission geometry was adopted for characterization of the samples after laser modification. The presented approach may lead to sophisticated marking of information in metal-glass nanocomposites. PMID:26368440

  12. Laser surface modification of electroplated, physically vapor deposited and plasma sprayed coatings

    SciTech Connect

    Dini, J.W.

    1996-05-01

    Lasers are used to modify surface characteristics in order to improve properties for a variety of industrial applications. Typical surface alterations include: transformation hardening, melting, cladding, alloying, coating, and smoothing. This paper is a critical review that covers surface alloying. It concentrates on coatings applied by electroplating, plasma spraying or physical vapor deposition and the resultant properties obtained after laser treatment. In many cases, significant improvement in properties such as corrosion resistance, wear resistance, creep strength, porosity, and structure was noted after coatings were exposed to a laser treatment. 112 refs., 12 figs., 4 tabs.

  13. Ion implantation induced phase transformation and enhanced crystallinity of as deposited copper oxide thin films by pulsed laser deposition

    NASA Astrophysics Data System (ADS)

    Bind, Umesh Chandra; Dutta, Raj Kumar; Sekhon, Gurpreet Kaur; Yadav, Kanhaiya Lal; Krishna, J. B. M.; Menon, Ranjini; Nabhiraj, P. Y.

    2015-08-01

    Copper oxide thin film of about 260-280 nm thickness was deposited using pulsed laser deposition (PLD) on glass substrate at 350 °C and post depositional sample treatment was performed by ion implantation with 50 keV N5+ ion beam with varying particle fluence. Amorphous copper oxide thin film deposited at 80 mTorr partial pressure of oxygen was transformed to cubic Cu2O phase (20.2 nm) when implanted at 1 × 1016 particles/cm2. While mixed Cu2O and CuO phases in the thin film deposited at 100 mTorr oxygen pressure was transformed to single phase of Cu2O (23.5 nm), with enhanced crystallinity when implanted with 2.5 × 1015 particles/cm2. The phase transformation and improved crystallinity is attributed to thermal effect owing to stopping of incident ion beam. Implantation with higher particle fluence led to transformation to CuO phase with reduced crystallite sized and the increased electrical conductivity.

  14. Improved hardening theory for cyclic plasticity.

    NASA Technical Reports Server (NTRS)

    Vos, R. G.; Armstrong, W. H.

    1973-01-01

    A temperature-dependent version of a combined hardening theory, including isotropic and kinematic hardening, is presented within the framework of recent plasticity formulations. This theory has been found to be especially useful in finite-element analysis of aerospace vehicle engines under conditions of large plastic strain and low-cycle fatigue.

  15. Kinematic hardening of a porous limestone

    NASA Astrophysics Data System (ADS)

    Cheatham, J. B.; Allen, M. B.; Celle, C. C.

    1984-10-01

    A concept for a kinematic hardening yield surface in stress space for Cordova Cream limestone (Austin Chalk) developed by Celle and Cheatham (1981) has been improved using Ziegler's modification of Prager's hardening rule (Ziegler, 1959). Data to date agree with the formulated concepts. It is shown how kinematic hardening can be used to approximate the yield surface for a wide range of stress states past the initial yield surface. The particular difficulty of identifying the yield surface under conditions of unloading or extension is noted. A yield condition and hardening rule which account for the strain induced anisotropy in Cordova Cream Limestone were developed. Although the actual yield surface appears to involve some change of size and shape, it is concluded that true kinematic hardening provides a basis for engineering calculations.

  16. Challenges in hardening technologies using shallow-trench isolation

    SciTech Connect

    Shaneyfelt, M.R.; Dodd, P.E.; Draper, B.L.; Flores, R.S.

    1998-02-01

    Challenges related to radiation hardening CMOS technologies with shallow-trench isolation are explored. Results show that trench hardening can be more difficult than simply replacing the trench isolation oxide with a hardened field oxide.

  17. Effect of phase transformation on optical and dielectric properties of pulsed laser deposited ZnTiO3 thin films

    NASA Astrophysics Data System (ADS)

    Jain, Praveen K.; Salim, Mohammad; Kaur, Davinder

    2016-04-01

    Zinc titanate (ZnTiO3) ceramics were prepared by conventional solid state reaction method using ZnO and TiO2 in a molar ratio of 1:1 with optimized parameters. It was found that the sample sintered at 800 °C for 12 h exhibit single hexagonal phase of ZnTiO3. ZnTiO3 thin film have been deposited on ITO coated glass substrate using pulsed laser deposition (PLD) technique employing a KrF laser source (λ = 248 nm). In present work, the effect of substrate temperature, which leads to transformation of hexagonal phase to cubic phase, has been studied. The XRD pattern revealed that pure hexagonal phase of ZnTiO3 appear upto 400 °C and more increment in substrate temperature leads to transformation of hexagonal phase to cubic phase. We have observed the blue shift in absorption edge at lower temperature. When the substrate temperature increases from 300 to 400 °C the band gap decreases due to strong hexagonal phase, but more increment in substrate temperature increases the band gap causes by change of phase from hexagonal to cubic. The dielectric constant of ZnTiO3 thin film increases as the substrate temperature increases due to the enhancement in crystallinity and improved morphology.

  18. Hybrid CO2 laser/waterjet (CO2-LWJ) cutting of Polycrystalline Cubic Boron Nitride (PCBN) blanks with phase transformation induced fracture

    NASA Astrophysics Data System (ADS)

    Wu, Zhuoru; Melaibari, Ammar A.; Molian, Pal; Shrotriya, Pranav

    2015-07-01

    The present paper investigates a transformation induced fracture mechanism for the cutting of Polycrystalline Cubic Boron Nitride (PCBN) sample by a hybrid CO2 laser/waterjet (CO2-LWJ) manufacturing process. In CO2-LWJ machining, a laser was used for local heating followed by waterjet quenching leading to fracture propagation along the sample surface. Cutting results indicate that as line energy of the laser was increased the sample response transitioned from scribing to through cutting. Raman spectroscopy analysis of the cut surface indicates that laser heated PCBN undergoes chemical phase transformation from sp3-bonded cubic Boron Nitride (cBN) into hexagonal Boron Nitride (hBN) and other sp2-bonded phases. The sp2-bonded structure occupies more volume than sp3-bonded structure such that the transformed material has a tendency to expand the original material and leads to surface deformation around the cutting path. Surface profile of the cut samples was experimentally measured using profilometry and compared with numerical predictions in order to estimate the expansion strain and dimensions of transformation region. Based on the obtained expansion strain and transformation zone, stress fields and crack driving forces were computed for channeling cracks that result in material separation. Comparison of the crack driving forces with fracture toughness of PCBN shows that transformation induced crack propagation is the feasible mechanism for cutting during CO2-LWJ machining.

  19. Chemical and microstructural transformations in lithium iron phosphate battery electrodes following pulsed laser exposure

    NASA Astrophysics Data System (ADS)

    Lutey, Adrian H. A.; Fiorini, Maurizio; Fortunato, Alessandro; Ascari, Alessandro

    2014-12-01

    Multi-layer lithium iron phosphate (LFP) battery electrodes are exposed to nanosecond pulsed laser radiation of wavelength 1064 nm. Test parameters are chosen to achieve characteristic interaction types ranging from partial incision of the active coating layers only to complete penetration of the electrodes with high visual cut quality. Raman spectroscopy is performed on unexposed regions and at points approaching each incision, highlighting changes in chemical composition and microstructure in the heat affected zone (HAZ). Thermogravimetric analysis is performed on the unexposed electrode active materials to distinguish the development of compositional changes under conditions of slow heating below the melting and sublimation temperatures. A brief theoretical description of the physical phenomena taking place during laser exposure is provided in terms of direct ablation during each laser pulse and vaporization or thermal degradation due to conductive heat transfer on a much longer time-scale, with characteristics of the HAZ reported in terms of these changes. For all laser exposures carried out in the study, chemical and microstructural changes are limited to the visible HAZ. Some degree of oxidation and LFP olivine phase degradation is observed in the cathode, while the polycrystalline graphite structure becomes less ordered in the anode. Where complete penetration is achieved, melting of the cathode active layer and combustion of the anode active layer take place near the cut edge due to thermal conduction from the metallic conductive layers. The presented results provide insight into the effects of laser processing on LFP electrode integrity.

  20. Automation and Control of an Imaging Internal Laser Desorption Fourier Transform Mass Spectrometer (I2LD-FTMS)

    SciTech Connect

    McJunkin, Timothy R; Tranter, Troy Joseph; Scott, Jill Rennee

    2002-06-01

    This paper describes the automation of an imaging internal source laser desorption Fourier transform mass spectrometer (I2LD-FTMS). The I2LD-FTMS consists of a laser-scanning device [Scott and Tremblay, Rev. Sci. Instrum. 2002, 73, 1108–1116] that has been integrated with a laboratory-built FTMS using a commercial data acquisition system (ThermoFinnigan FT/MS, Bremen, Germany). A new user interface has been developed in National Instrument's (Austin, Texas) graphical programming language LabVIEW to control the motors of the laser positioning system and the commercial FTMS data acquisition system. A feature of the FTMS software that allows the user to write macros in a scripting language is used creatively to our advantage in creating a mechanism to control the FTMS from outside its graphical user interface. The new user interface also allows the user to configure target locations. Automation of the data analysis along with data display using commercial graphing software is also described.

  1. Fourier-transform spectroscopy using an Er-doped fiber femtosecond laser by sweeping the pulse repetition rate.

    PubMed

    Lee, Keunwoo; Lee, Joohyung; Jang, Yoon-Soo; Han, Seongheum; Jang, Heesuk; Kim, Young-Jin; Kim, Seung-Woo

    2015-01-01

    Femtosecond lasers allow for simultaneous detection of multiple absorption lines of a specimen over a broad spectral range of infrared or visible light with a single spectroscopic measurement. Here, we present an 8-THz bandwidth, 0.5-GHz resolution scheme of Fourier-transform spectroscopy using an Er-doped fiber femtosecond laser. A resolving power of 1.6 × 10(4) about a 1560-nm center wavelength is achieved by sweeping the pulse repetition rate of the light source on a fiber Mach-Zehnder interferometer configured to capture interferograms with a 0.02-fs temporal sampling accuracy through a well-stabilized 60-m unbalance arm length. A dual-servo mechanism is realized by combining a mechanical linear stage with an electro-optic modulator (EOM) within the fiber laser cavity, enabling stable sweeping control of the pulse repetition rate over a 1.0-MHz scan range with 0.4-Hz steps with reference to the Rb clock. Experimental results demonstrate that the P-branch lines of the H(13)CN reference cell can be observed with a signal-to-noise ratio reaching 350 for the most intense line. PMID:26503257

  2. Vacuum compatible sample positioning device for matrix assisted laser desorption/ionization Fourier transform ion cyclotron resonance mass spectrometry imaging

    PubMed Central

    Aizikov, Konstantin; Smith, Donald F.; Chargin, David A.; Ivanov, Sergei; Lin, Tzu-Yung; Heeren, Ron M. A.; O’Connor, Peter B.

    2011-01-01

    The high mass accuracy and resolving power of Fourier transform ion cyclotron resonance mass spectrometers (FT-ICR MS) make them ideal mass detectors for mass spectrometry imaging (MSI), promising to provide unmatched molecular resolution capabilities. The intrinsic low tolerance of FT-ICR MS to RF interference, however, along with typically vertical positioning of the sample, and MSI acquisition speed requirements present numerous engineering challenges in creating robotics capable of achieving the spatial resolution to match. This work discusses a two-dimensional positioning stage designed to address these issues. The stage is capable of operating in ∼1 × 10–8 mbar vacuum. The range of motion is set to 100 mm × 100 mm to accommodate large samples, while the positioning accuracy is demonstrated to be less than 0.4 micron in both directions under vertical load over the entire range. This device was integrated into three different matrix assisted laser desorption/ionization (MALDI) FT-ICR instruments and showed no detectable RF noise. The “oversampling” MALDI-MSI experiments, under which the sample is completely ablated at each position, followed by the target movement of the distance smaller than the laser beam, conducted on the custom-built 7T FT-ICR MS demonstrate the stability and positional accuracy of the stage robotics which delivers high spatial resolution mass spectral images at a fraction of the laser spot diameter. PMID:21639522

  3. Fourier-transform spectroscopy using an Er-doped fiber femtosecond laser by sweeping the pulse repetition rate

    NASA Astrophysics Data System (ADS)

    Lee, Keunwoo; Lee, Joohyung; Jang, Yoon-Soo; Han, Seongheum; Jang, Heesuk; Kim, Young-Jin; Kim, Seung-Woo

    2015-10-01

    Femtosecond lasers allow for simultaneous detection of multiple absorption lines of a specimen over a broad spectral range of infrared or visible light with a single spectroscopic measurement. Here, we present an 8-THz bandwidth, 0.5-GHz resolution scheme of Fourier-transform spectroscopy using an Er-doped fiber femtosecond laser. A resolving power of 1.6 × 104 about a 1560-nm center wavelength is achieved by sweeping the pulse repetition rate of the light source on a fiber Mach-Zehnder interferometer configured to capture interferograms with a 0.02-fs temporal sampling accuracy through a well-stabilized 60-m unbalance arm length. A dual-servo mechanism is realized by combining a mechanical linear stage with an electro-optic modulator (EOM) within the fiber laser cavity, enabling stable sweeping control of the pulse repetition rate over a 1.0-MHz scan range with 0.4-Hz steps with reference to the Rb clock. Experimental results demonstrate that the P-branch lines of the H13CN reference cell can be observed with a signal-to-noise ratio reaching 350 for the most intense line.

  4. Vacuum compatible sample positioning device for matrix assisted laser desorption/ionization Fourier transform ion cyclotron resonance mass spectrometry imaging

    SciTech Connect

    Aizikov, Konstantin; Lin, Tzu-Yung; Smith, Donald F.; Heeren, Ron M. A.; Chargin, David A.; Ivanov, Sergei; O'Connor, Peter B.

    2011-05-15

    The high mass accuracy and resolving power of Fourier transform ion cyclotron resonance mass spectrometers (FT-ICR MS) make them ideal mass detectors for mass spectrometry imaging (MSI), promising to provide unmatched molecular resolution capabilities. The intrinsic low tolerance of FT-ICR MS to RF interference, however, along with typically vertical positioning of the sample, and MSI acquisition speed requirements present numerous engineering challenges in creating robotics capable of achieving the spatial resolution to match. This work discusses a two-dimensional positioning stage designed to address these issues. The stage is capable of operating in {approx}1 x 10{sup -8} mbar vacuum. The range of motion is set to 100 mm x 100 mm to accommodate large samples, while the positioning accuracy is demonstrated to be less than 0.4 micron in both directions under vertical load over the entire range. This device was integrated into three different matrix assisted laser desorption/ionization (MALDI) FT-ICR instruments and showed no detectable RF noise. The ''oversampling'' MALDI-MSI experiments, under which the sample is completely ablated at each position, followed by the target movement of the distance smaller than the laser beam, conducted on the custom-built 7T FT-ICR MS demonstrate the stability and positional accuracy of the stage robotics which delivers high spatial resolution mass spectral images at a fraction of the laser spot diameter.

  5. Fourier-transform spectroscopy using an Er-doped fiber femtosecond laser by sweeping the pulse repetition rate

    PubMed Central

    Lee, Keunwoo; Lee, Joohyung; Jang, Yoon-Soo; Han, Seongheum; Jang, Heesuk; Kim, Young-Jin; Kim, Seung-Woo

    2015-01-01

    Femtosecond lasers allow for simultaneous detection of multiple absorption lines of a specimen over a broad spectral range of infrared or visible light with a single spectroscopic measurement. Here, we present an 8-THz bandwidth, 0.5-GHz resolution scheme of Fourier-transform spectroscopy using an Er-doped fiber femtosecond laser. A resolving power of 1.6 × 104 about a 1560-nm center wavelength is achieved by sweeping the pulse repetition rate of the light source on a fiber Mach-Zehnder interferometer configured to capture interferograms with a 0.02-fs temporal sampling accuracy through a well-stabilized 60-m unbalance arm length. A dual-servo mechanism is realized by combining a mechanical linear stage with an electro-optic modulator (EOM) within the fiber laser cavity, enabling stable sweeping control of the pulse repetition rate over a 1.0-MHz scan range with 0.4-Hz steps with reference to the Rb clock. Experimental results demonstrate that the P-branch lines of the H13CN reference cell can be observed with a signal-to-noise ratio reaching 350 for the most intense line. PMID:26503257

  6. Femtosecond laser induced tunable surface transformations on (111) Si aided by square grids diffraction

    SciTech Connect

    Han, Weina; Jiang, Lan; Li, Xiaowei Liu, Yang

    2015-12-21

    We report an extra freedom to modulate the femtosecond laser energy distribution to control the surface ablated structures through a copper-grid mask. Due to the reduced deposited pulse energy by changing the scanning speed or the pulse fluence, a sequential evolution of three distinctly different surface patterns with periodic distributions is formed, namely, striped ripple lines, ripple microdots, and surface modification. By changing the scanning speed, the number of the multiple dots in a lattice can be modulated. Moreover, by exploring the ablation process through the copper grid mask, it shows an abnormal enhanced ablation effect with strong dependence of the diffraction-aided fs laser ablated surface structures on polarization direction. The sensitivity shows a quasi-cosinusoid-function with a periodicity of π/2. Particularly, the connection process of striped ripple lines manifests a preferential formation direction with the laser polarization.

  7. Electrically driven hybrid Si/III-V Fabry-Pérot lasers based on adiabatic mode transformers.

    PubMed

    Ben Bakir, B; Descos, A; Olivier, N; Bordel, D; Grosse, P; Augendre, E; Fulbert, L; Fedeli, J M

    2011-05-23

    We report the first demonstration of an electrically driven hybrid silicon/III-V laser based on adiabatic mode transformers. The hybrid structure is formed by two vertically superimposed waveguides separated by a 100-nm-thick SiO2 layer. The top waveguide, fabricated in an InP/InGaAsP-based heterostructure, serves to provide optical gain. The bottom Si-waveguides system, which supports all optical functions, is constituted by two tapered rib-waveguides (mode transformers), two distributed Bragg reflectors (DBRs) and a surface-grating coupler. The supermodes of this hybrid structure are controlled by an appropriate design of the tapers located at the edges of the gain region. In the middle part of the device almost all the field resides in the III-V waveguide so that the optical mode experiences maximal gain, while in regions near the III-V facets, mode transformers ensure an efficient transfer of the power flow towards Si-waveguides. The investigated device operates under quasi-continuous wave regime. The room temperature threshold current is 100 mA, the side-mode suppression ratio is as high as 20 dB, and the fiber-coupled output power is ~7 mW. PMID:21643289

  8. Cyclic hardening mechanisms in Nimonic 80A

    NASA Technical Reports Server (NTRS)

    Lerch, B. A.; Gerold, V.

    1987-01-01

    A nickel base superalloy was fatigued under constant plastic strain range control. The hardening response was investigated as a function of plastic strain range and particle size of the gamma prime phase. Hardening was found to be a function of the slip band spacing. Numerous measurements of the slip band spacing and other statistical data on the slip band structures were obtained. Interactions between intersecting slip systems were shown to influence hardening. A Petch-Hall model was found to describe best this relationship between the response stress and the slip band spacing.

  9. Fatigue hardening in niobium single crystals.

    NASA Technical Reports Server (NTRS)

    Doner, M.; Diprimio, J. C.; Salkovitz, E. I.

    1973-01-01

    Nb single crystals of various orientations were cyclically deformed in tension-compression under strain control. At low strain amplitudes all crystals oriented for single slip and some oriented for multiple slip showed a two stage hardening. When present, the first stage was characterized with almost no cyclic work hardening. The rate of hardening in the second stage increased with strain amplitude and the amount of secondary slip. In crystals oriented for single slip kink bands developed on their side faces during rapid hardening stage which resulted in considerable amount of asterism in Laue spots. A cyclic stress-strain curve independent of prior history was found to exist which was also independent of crystal orientation. Furthermore, this curve differed only slightly from that of polycrystalline Nb obtained from data in literature.

  10. Alloy solution hardening with solute pairs

    DOEpatents

    Mitchell, John W.

    1976-08-24

    Solution hardened alloys are formed by using at least two solutes which form associated solute pairs in the solvent metal lattice. Copper containing equal atomic percentages of aluminum and palladium is an example.

  11. Process for hardening the surface of polymers

    DOEpatents

    Mansur, L.K.; Lee, E.H.

    1992-07-14

    Hard surfaced polymers and the method for making them is generally described. Polymers are subjected to simultaneous multiple ion beam bombardment, that results in a hardening of the surface and improved wear resistance. 1 figure.

  12. Process for hardening the surface of polymers

    DOEpatents

    Mansur, Louis K.; Lee, Eal H.

    1992-01-01

    Hard surfaced polymers and the method for making them is generally described. Polymers are subjected to simultaneous multiple ion beam bombardment, that results in a hardening of the surface and improved wear resistance.

  13. Structural characterization of phospholipids by matrix-assisted laser desorption/ionization Fourier transform ion cyclotron resonance mass spectrometry.

    PubMed

    Marto, J A; White, F M; Seldomridge, S; Marshall, A G

    1995-11-01

    Matrix-assisted laser desorption/ionization (MALDI) Fourier transform ion cyclotron resonance mass spectrometry provides for structural analysis of the principal biological phospholipids: glycerophosphatidylcholine, -ethanolamine, -serine, and -inositol. Both positive and negative molecular or quasimolecular ions are generated in high abundance. Isolated molecular ions may be collisionally activated in the source side of a dual trap mass analyzer, yielding fragments serving to identify the polar head group (positive ion mode) and fatty acid side chains (negative ion mode). Azimuthal quadrupolar excitation following collisionally activated dissociation refocuses productions close to the solenoid axis; subsequent transfer of product ions to the analyzer ion trap allows for high-resolution mass analysis. Cyro-cooling of the sample probe with liquid nitrogen greatly reduces matrix adduction encountered in the negative ion mode. PMID:8633761

  14. Molecular identification of foreign inclusions in inflammatory tissue surrounding metal implants by Fourier transform laser microprobe mass spectrometry.

    PubMed

    De Nollin, S; Poels, K; Van Vaeck, L; De Clerck, N; Bakker, A; Duwel, V; Vandevelde, D; Van Marck, E

    1997-01-01

    Fourier transform laser microprobe mass spectrometry (FT LMMS) is a novel technique for micro-analysis of solids with a lateral resolution in the 5 microns range. One of the major advantages of the technique is the capability to perform characterisation of the molecular composition of both organic and inorganic compounds. The information is directly deduced from the signals without the aid of reference spectra. FT LMMS was applied to the characterisation of black tissue fragments in a biopsy from a patient, in which a constrained condylar nodular knee system was implanted ten years ago. The tissue contained numerous foreign giant cells with a black non-birefringent pigment in their cytoplasm. FT LMMS analysis allowed us to detect directly by means of molecular signals, that the debris consisted primarily of titanium oxide and not metallic titanium, while the implant itself only contained titanium. PMID:9258958

  15. Generation of Widely Tunable Fourier-Transform Pulsed Terahertz Radiation Using Narrowband Near-Infrared Laser Radiation

    NASA Astrophysics Data System (ADS)

    Liu, Jinjun; Haase, Christa; Merkt, Frédéric

    2009-06-01

    Widely tunable, Fourier-transform-limited pulses of terahertz (THz) radiation have been generated by optical frequency deference using (i) crystals of the highly nonlinear organic salt 4-N,N-dimethylamino-4^'-N^'-methyl stilbazolium tosylate (DAST), (ii) zinc telluride (ZnTe) crystals, and (iii) gallium phosphide (GaP) crystals. Outputs from two narrowband (Δν<1 MHz, λ˜800 nm) cw titanium-doped sapphire (Ti:Sa) ring lasers with a well-controlled frequency difference were shaped into pulses using acousto-optic modulators, coupled into an optical fiber, pulse amplified in Nd:YAG-pumped Ti:Sa crystals and used as optical sources to pump the THz nonlinear crystals. The THz radiation was detected over a broad frequency range and its bandwidth was determined to be ˜10 MHz. Absorption spectra of gas phase molecules including HF and OCS using the THz source will be presented.

  16. Decline in Radiation Hardened Microcircuit Infrastructure

    NASA Technical Reports Server (NTRS)

    LaBel, Kenneth A.

    2015-01-01

    Two areas of radiation hardened microcircuit infrastructure will be discussed: 1) The availability and performance of radiation hardened microcircuits, and, and 2) The access to radiation test facilities primarily for proton single event effects (SEE) testing. Other areas not discussed, but are a concern include: The challenge for maintaining radiation effects tool access for assurance purposes, and, the access to radiation test facilities primarily for heavy ion single event effects (SEE) testing. Status and implications will be discussed for each area.

  17. Femtosecond laser-induced phase transformations in amorphous Cu{sub 77}Ni{sub 6}Sn{sub 10}P{sub 7} alloy

    SciTech Connect

    Zhang, Y.; Zou, G.; Wu, A.; Bai, H.; Liu, L.; Chen, N.; Zhou, Y.

    2015-01-14

    In this study, the femtosecond laser-induced crystallization of CuNiSnP amorphous ribbons was investigated by utilizing an amplified Ti:sapphire laser system. X-ray diffraction and scanning electronic microscope were applied to examine the phase and morphology changes of the amorphous ribbons. Micromachining without crystallization, surface patterning, and selective crystallization were successfully achieved by changing laser parameters. Obvious crystallization occurred under the condition that the laser fluence was smaller than the ablation threshold, indicating that the structural evolution of the material depends strongly on the laser parameters. Back cooling method was used to inhibit heat accumulation; a reversible transformation between the disordered amorphous and crystalline phases can be achieved by using this method.

  18. 7 CFR 58.641 - Hardening and storage.

    Code of Federal Regulations, 2014 CFR

    2014-01-01

    ... 7 Agriculture 3 2014-01-01 2014-01-01 false Hardening and storage. 58.641 Section 58.641... Procedures § 58.641 Hardening and storage. Immediately after the semifrozen product is placed in its intended container it shall be placed in a hardening tunnel or hardening room to continue the freezing process....

  19. 7 CFR 58.641 - Hardening and storage.

    Code of Federal Regulations, 2012 CFR

    2012-01-01

    ... 7 Agriculture 3 2012-01-01 2012-01-01 false Hardening and storage. 58.641 Section 58.641... Procedures § 58.641 Hardening and storage. Immediately after the semifrozen product is placed in its intended container it shall be placed in a hardening tunnel or hardening room to continue the freezing process....

  20. 7 CFR 58.641 - Hardening and storage.

    Code of Federal Regulations, 2013 CFR

    2013-01-01

    ... 7 Agriculture 3 2013-01-01 2013-01-01 false Hardening and storage. 58.641 Section 58.641... Procedures § 58.641 Hardening and storage. Immediately after the semifrozen product is placed in its intended container it shall be placed in a hardening tunnel or hardening room to continue the freezing process....

  1. 7 CFR 58.641 - Hardening and storage.

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    ... 7 Agriculture 3 2010-01-01 2010-01-01 false Hardening and storage. 58.641 Section 58.641... Procedures § 58.641 Hardening and storage. Immediately after the semifrozen product is placed in its intended container it shall be placed in a hardening tunnel or hardening room to continue the freezing process....

  2. 7 CFR 58.641 - Hardening and storage.

    Code of Federal Regulations, 2011 CFR

    2011-01-01

    ... 7 Agriculture 3 2011-01-01 2011-01-01 false Hardening and storage. 58.641 Section 58.641... Procedures § 58.641 Hardening and storage. Immediately after the semifrozen product is placed in its intended container it shall be placed in a hardening tunnel or hardening room to continue the freezing process....

  3. Exploring Biosignatures Associated with Thenardite by Geomatrix-Assisted Laser Desorption/Ionization Fourier Transform Mass Spectrometry (GALDI-FTMS)

    SciTech Connect

    C. Doc Richardson; Nancy W. Hinman; Timothy R. McJunkin; Jill R. Scott

    2008-07-01

    Geomatrix-assisted laser desorption/ionization (GALDI) in conjunction with a Fourier transform mass spectrometer (FTMS) has been employed to determine how well bio/organic molecules associated with the mineral thenardite (Na2SO4) can be detected. GALDI is based on the ability of the mineral host to assist desorption and ionization of bio/organic molecules without additional sample preparation. When glycine was mixed with thenardite, glycine was deprotonated to produce C2H4NO2 at m/z 74.025. The combination of stearic acid with thenardite produced a complex cluster ion at m/z 390.258 in the negative mode, which was assigned a composition of C18H39O7Na . A natural sample of thenardite from Searles Lake in California also produced a peak at m/z 390.260. The bio/organic signatures in both the laboratory-based and natural samples were heterogeneously dispersed as revealed by chemical imaging. The detection limits for the stearic acid and thenardite combination was estimated to be 3 parts per trillion or ~7 zeptomoles per laser spot. Attempts to improve the signal-to-noise ratio by co-adding FTMS data predetermined to contain the biosignatures of interest revealed problems due to a lack of phase coherence between data sets.

  4. Matrix-free mass spectrometric imaging using laser desorption ionisation Fourier transform ion cyclotron resonance mass spectrometry.

    PubMed

    Goodwin, Richard J A; Pitt, Andrew R; Harrison, David; Weidt, Stefan K; Langridge-Smith, Pat R R; Barrett, Michael P; Logan Mackay, C

    2011-04-15

    Mass spectrometry imaging (MSI) is a powerful tool in metabolomics and proteomics for the spatial localization and identification of pharmaceuticals, metabolites, lipids, peptides and proteins in biological tissues. However, sample preparation remains a crucial variable in obtaining the most accurate distributions. Common washing steps used to remove salts, and solvent-based matrix application, allow analyte spreading to occur. Solvent-free matrix applications can reduce this risk, but increase the possibility of ionisation bias due to matrix adhesion to tissue sections. We report here the use of matrix-free MSI using laser desorption ionisation performed on a 12 T Fourier transform ion cyclotron resonance (FTICR) mass spectrometer. We used unprocessed tissue with no post-processing following thaw-mounting on matrix-assisted laser desorption ionisation (MALDI) indium-tin oxide (ITO) target plates. The identification and distribution of a range of phospholipids in mouse brain and kidney sections are presented and compared with previously published MALDI time-of-flight (TOF) MSI distributions. PMID:21416534

  5. An optical system to transform the output beam of a quantum cascade laser to be uniform

    NASA Astrophysics Data System (ADS)

    Jacobson, Jordan M.

    Quantum cascade lasers (QCLs) are a candidate for calibration sources in space-based remote sensing applications. However, the output beam from a QCL has some characteris- tics that are undesirable in a calibration source. The output beam from a QCL is polarized, both temporally and spatially coherent, and has a non-uniform bivariate Gaussian prole. These characteristics need to be mitigated before QCLs can be used as calibration sources. This study presents the design and implementation of an optical system that manipulates the output beam from a QCL so that it is spatially and angularly uniform with reduced coherence and polarization. (85 pages).

  6. On the Decomposition of Martensite During Bake Hardening of Thermomechanically Processed TRIP Steels

    SciTech Connect

    Pereloma, E. V.; Miller, Michael K; Timokhina, I. B.

    2008-01-01

    Thermomechanically processed (TMP) CMnSi transformation-induced plasticity (TRIP) steels with and without additions of Nb, Mo, or Al were subjected to prestraining and bake hardening. Atom probe tomography (APT) revealed the presence of fine C-rich clusters in the martensite of all studied steels after the thermomechanical processing. After bake hardening, the formation of iron carbides, containing from 25 to 90 at. pct C, was observed. The evolution of iron carbide compositions was independent of steel composition and was a function of carbide size.

  7. Diode laser and Fourier transform infrared spectroscopy of jet-cooled nickel carbonyl

    NASA Astrophysics Data System (ADS)

    Davies, Paul B.; Martin, Nicholas A.; Nunes, Michael D.; Pape, David A.; Russell, Douglas K.

    1990-08-01

    Infrared absorption spectra of Ni(CO)4 in the region of its 510 band have been measured in supersonic jets using diode lasers and FTIR. The 510 band consisted of an intense Q branch and well-resolved P and R branches which clearly showed the effects of nuclear spin statistics. The analysis of 114 fundamental band transitions yielded the following effective parameters, which include small Coriolis effects (3σ uncertainties in parenthesis) ν˜0=2061.314 4(45) cm-1, B0=0.035 721 3(30) cm-1, B5=0.035 670 6(30) cm-1. The band center is blue-shifted by 3.5 cm-1 from the room temperature value due to the contribution of hot bands and higher-rotational distributions in the room temperature spectra. Weaker features near the 510 Q branch in the diode laser spectra are assigned to the Q branches of two hot bands. Their spectra, optimized using higher concentrations of Ni(CO)4 in He or Ar seed gas, were analyzed to give rotation, vibration-rotation and anharmonicity parameters. The effective hot band centers are: ν˜0(510411) =2060.996 4(50) cm-1, ν˜0(510811) =2061.114 8(48) cm-1.

  8. Phase transformations on the surface of YAG composite ceramics under the action of directed laser treatment

    NASA Astrophysics Data System (ADS)

    Vlasova, M.; Márquez Aguilar, P. A.; Escobar Martinez, A.; Kakazey, M.; Guardian Tapia, R.; Trujillo Estrada, A.

    2016-07-01

    The laser treatment of composite ceramics based on Y3Al5O12 with Y2Ti2O7, Al2Y4O9, and Al2O3 additives is accompanied by the melting of the surface layer and formation of tracks. In the volume of tracks, the partial dissociation of Y3Al5O12, Y2Ti2O7, and Al2Y4O9, and the formation of new phases such as YAlO3 of orthorhombic and hexagonal modifications along with the appearance of additional content of Y3Al5O12 and Al2O3 are observed. The content of all these phases depends on the irradiation mode and the phase composition of the ceramics. With increase in the corundum content in ceramic specimens, in the tracks, the Al2O3 content increases, and the Y3Al5O12 content decreases. In the volume of tracks, Y3Al5O12 crystallites are textured. The size of YAG crystallites and their crystallographic texturing depend on the irradiation mode and Y3Al5O12/Al2O3 phase ratio. On the surface of tracks, a layer enriched in YAlO3 forms. Thus, as a result of laser treatment, on the surface of the ceramics, a two-layer coating with a radically new phase composition and specific texture of Y3Al5O12 crystallites forms.

  9. Identifying Deformation and Strain Hardening Behaviors of Nanoscale Metallic Multilayers Through Nano-wear Testing

    DOE PAGESBeta

    Economy, David Ross; Mara, Nathan A.; Schoeppner, R.; Schultz, Bradley M.; Unocic, Raymond R.; Kennedy, Marian S.

    2016-01-13

    In complex loading conditions (e.g. sliding contact), mechanical properties, such as strain hardening and initial hardness, will dictate the long-term performance of materials systems. With this in mind, the strain hardening behaviors of Cu/Nb nanoscale metallic multilayer systems were examined by performing nanoindentation tests within nanoscratch wear boxes and undeformed, as-deposited regions. Both the architecture and substrate influence were examined by utilizing three different individual layer thicknesses (2, 20, and 100 nm) and two total film thicknesses (1 and 10 μm). After nano-wear deformation, multilayer systems with thinner layers showed less volume loss as measured by laser scanning microscopy. Additionally,more » the hardness of the deformed regions significantly rose with respect to the as-deposited measurements, which further increased with greater wear loads. Strain hardening exponents for multilayers with thinner layers (2 and 20 nm, n ≈ 0.018 and n ≈ 0.022 respectively) were less than was determined for 100 nm systems (n ≈ 0.041). These results suggest that singledislocation based deformation mechanisms observed for the thinner systems limit the extent of achievable strain hardening. This conclusion indicates that impacts of both architecture strengthening and strain hardening must be considered to accurately predict multilayer performance during sliding contact across varying length scales.« less

  10. Identifying Deformation and Strain Hardening Behaviors of Nanoscale Metallic Multilayers Through Nano-wear Testing

    NASA Astrophysics Data System (ADS)

    Economy, D. Ross; Mara, N. A.; Schoeppner, R. L.; Schultz, B. M.; Unocic, R. R.; Kennedy, M. S.

    2016-03-01

    In complex loading conditions ( e.g., sliding contact), mechanical properties, such as strain hardening and initial hardness, will dictate the long-term performance of materials systems. With this in mind, the strain hardening behaviors of Cu/Nb nanoscale metallic multilayer systems were examined by performing nanoindentation tests within nanoscratch wear boxes and undeformed regions (as-deposited). Both the architecture and substrate influence were examined by utilizing three different individual layer thicknesses (2, 20, and 100 nm) and two total film thicknesses (1 and 10 µm). After nano-wear deformation, multilayer systems with thinner layers showed less volume loss as measured by laser scanning microscopy. Additionally, the hardness of the deformed regions significantly rose with respect to the as-deposited measurements, which further increased with greater wear loads. Strain hardening exponents for multilayers with thinner layers (2 and 20 nm, n ≈ 0.018 and n ≈ 0.022, respectively) were less than that determined for 100 nm systems ( n ≈ 0.041). These results suggest that single-dislocation-based deformation mechanisms observed for the thinner systems limit the extent of achievable strain hardening. This conclusion indicates that impacts of both architecture strengthening and strain hardening must be considered to accurately predict multilayer performance during sliding contact across varying length scales.

  11. Thermal stresses in chemically hardening elastic media with application to the molding process

    NASA Technical Reports Server (NTRS)

    Levitsky, M.; Shaffer, B. W.

    1974-01-01

    A method has been formulated for the determination of thermal stresses in materials which harden in the presence of an exothermic chemical reaction. Hardening is described by the transformation of the material from an inviscid liquid-like state into an elastic solid, where intermediate states consist of a mixture of the two, in a ratio which is determined by the degree of chemical reaction. The method is illustrated in terms of an infinite slab cast between two rigid mold surfaces. It is found that the stress component normal to the slab surfaces vanishes in the residual state, so that removal of the slab from the mold leaves the remaining residual stress unchanged. On the other hand, the residual stress component parallel to the slab surfaces does not vanish. Its distribution is described as a function of the parameters of the hardening process.

  12. Quantification of age hardening in maraging steels and an Ni-base superalloy

    SciTech Connect

    Sha, W.

    2000-02-01

    Age hardening process in metallic alloys due to precipitation can be quantified using phase transformation theories. Two ageing stages are of particular interest, for both theory and practice. The early stage of precipitation hardening is under the description of the Johnson-Mehl-Avrami equation. Wilson has recently provided a detailed theoretical analysis for early stages of ageing. Wilson successfully used equations in the quantification of early and over-ageing stages of hardening in an Fe-12Ni-6Mn maraging-type alloy. In the present work, these were applied to further alloys. All the hardness data were taken from published literature. Original references should be consulted for details of materials, testing and characterization.

  13. Isothermal age-hardening behaviour in a Au-1.6 wt% Ti alloy.

    PubMed

    Kim, H I; Seol, H J; Bae, D H; Shim, J Y; Takada, Y; Okuno, O

    1999-03-01

    This study describes research with a view to developing a new age-hardenable, high-carat dental gold alloy with better biocompatibility by addition of a small quantity of titanium to gold. The relationship between isothermal age-hardening and phase transformation of the Au-1.6 wt% Ti alloy was investigated by means of hardness testing, X-ray diffraction study, scanning electron microscopic observation and energy dispersive spectroscopy. The hardening in the initial stage of ageing seemed to be attributable to the continuous precipitation of the Au4Ti ordered phase in the supersaturated alpha solid solution matrix. The overaging with softening was attributed mainly to the formation of precipitates at the grain boundaries, which grew to bright lamellae and seemed to be composed of the Au4Ti phase. PMID:10786146

  14. Use of the Lorentz-Boosted Frame Transformation to Simulate Free-Electron Laser Amplifier Physics

    SciTech Connect

    Fawley, W. M.; Vay, J.-L.

    2009-01-22

    Recently it has been pointed out that numerical simulation of some systems containing charged particles with highly relativistic directed motion can by speeded up by orders of magnitude by choice of the proper Lorentz boosted frame. A particularly good example is that of short wavelength free-electron lasers (FELs) in which a high energy (E{sub 0}{>=}250 MeV) electron beam interacts with a static magnetic undulator. In the optimal boost frame with Lorentz factor {gamma}F, the red-shifted FEL radiation and blue shifted undulator have identical wavelengths and the number of required time-steps (presuming the Courant condition applies) decreases by a factor of {gamma}{sub F}{sup 2} for fully electromagnetic simulation.We have adapted the WARP code to apply this method to several FEL problems including coherent spontaneous emission (CSE) from pre-bunched e-beams, and strong exponential gain in a single pass amplifier configuration. We discuss our results and compare with those from the 'standard' FEL simulation approach which adopts the eikonal approximation for propagation of the radiation field.

  15. Use of the Lorentz-Boosted Frame Transformation to Simulate Free-Electron Laser Amplifier Physics

    SciTech Connect

    Fawley, W.M.; Vay, J.-L.

    2008-07-27

    Recently [1]it has been pointed out that numerical simulation of some systems containing charged particles with highly relativistic directed motion can by speeded up by orders of magnitude by choice of the proper Lorentz boosted frame. A particularly good example is that of short wavelength free-electron lasers (FELs) in which a high energy (E0>_ 250 MeV) electron beam interacts with a static magnetic undulator. In the optimal boost frame with Lorentz factor gamma F, the red-shifted FEL radiation and blue shifted undulator have identical wavelengths and the number of required time-steps (presuming the Courant condition applies) decreases by a factor of g2 F for fullyelectromagnetic simulation. We have adapted the WARP code [2]to apply this method to several FEL problems including coherent spontaneous emission (CSE) from pre-bunched e-beams, and strong exponential gain in a single pass amplifier configuration. We discuss our results and compare with those from the"standard" FEL simulation approach which adopts the eikonal approximation for propagation ofthe radiation field.

  16. Influence of slip system hardening assumptions on modeling stress dependence of work hardening

    NASA Astrophysics Data System (ADS)

    Miller, Matthew; Dawson, Paul

    1997-11-01

    Due to the discrete directional nature of processes such as crystallographic slip, the orientation of slip planes relative to a fixed set of loading axes has a direct effect on the magnitude of the external load necessary to induce dislocation motion (yielding). The effect such geometric or textural hardening has on the macroscopic flow stress can be quantified in a polycrystal by the average Taylor factor M¯. Sources of resistance to dislocation motion such as interaction with dislocation structures, precipitates, and grain boundaries, contribute to the elevation of the critically resolved shear strength τcrss. In continuum slip polycrystal formulations, material hardening phenomena are reflected in the slip system hardness equations. Depending on the model, the hardening equations and the mean field assumption can both affect geometric hardening through texture evolution. In this paper, we examine continuum slip models and focus on how the slip system hardening model and the mean field assumption affect the stress-strain response. Texture results are also presented within the context of how the texture affects geometric hardening. We explore the effect of employing slip system hardnesses averaged over different size scales. We first compare a polycrystal simulation employing a single hardness per crystal to one using a latent hardening formulation producing distinct slip system hardnesses. We find little difference between the amplitude of the single hardness and a crystal-average of the latent hardening values. The geometric hardening is different due to the differences in the textures predicted by each model. We also find that due to the high degree of symmetry in an fcc crystal, macroscopic stress-strain predictions using simulations employing crystal- and aggregateaveraged hardnesses are nearly identical. We find this to be true for several different mean field assumptions. An aggregate-averaged hardness may be preferred in light of the difficulty

  17. Gas-phase plume from laser-irradiated fiberglass-reinforced polymers via imaging fourier transform spectroscopy.

    PubMed

    Acosta, Roberto I; Gross, Kevin C; Perram, Glen P; Johnson, Shane M; Dao, Ly; Medina, David F; Roybal, Robert; Black, Paul

    2014-01-01

    Emissive plumes from laser-irradiated fiberglass-reinforced polymers (FRP) were investigated using a mid-infrared imaging Fourier transform spectrometer, operating at fast framing rates (50 kHz imagery and 2.5 Hz hyperspectral imagery) with adequate spatial (0.81 mm(2) per pixel) and spectral resolution (2 cm(-1)). Fiberglass-reinforced polymer targets were irradiated with a 1064 nm continuous wave neodymium-doped yttrium aluminum garnet (Nd:YAG) laser for 60 s at 100 W in air. Strong emissions from H(2)O, CO, CO(2), and hydrocarbons were observed between 1800 and 5000 cm(-1). A single-layer radiative transfer model was developed for the spectral region from 2000 to 2400 cm(-1) to estimate spatial maps of temperature and column densities of CO and CO(2) from the hyperspectral imagery. The spectral model was used to compute the absorption cross sections of CO and CO(2) using spectral line parameters from the high-temperature extension of the HITRAN. The analysis of pre-combustion spectra yields effective temperatures rising from ambient to 1200 K and suddenly increasing to 1515 K upon combustion. The peak signal-to-noise ratio for a single spectrum exceeds 60:1, enabling temperature and column density determinations with low statistical error. For example, the spectral analysis for a single pixel within a single frame yields an effective temperature of 1019 ± 6 K, and CO and CO(2) column densities of 1.14 ± 0.05 and 1.11 ± 0.03 × 10(18) molec/cm(2), respectively. Systematic errors associated with the radiative transfer model dominate, yielding effective temperatures with uncertainties of >100 K and column densities to within a factor of 2-3. Hydrocarbon emission at 2800 to 3200 cm(-1) is well correlated with CO column density. PMID:25014838

  18. Detection of Biosignatures in Natural and Microbial Cultured Jarosites Using Laser- Desorption Fourier Transform Mass Spectrometry: Implications for Astrobiology

    NASA Astrophysics Data System (ADS)

    Kotler, J.; Hinman, N. W.; Yan, B.; Stoner, D. L.; Scott, J. R.

    2006-12-01

    The jarosite group minerals have received increasing attention since the discovery by the Mars Exploration Rover-Opportunity of jarosite on the Martian surface. The general chemical formula for jarosite is XFe3(SO4)2(OH)6 where the X represents both monovalent and divalent cations that can occupy the axial positions in the crystal structure. Commonly found ions include K+, Na+, H3O+, NH4+, and Pb2+ with reports of other large ions occupying this position in the literature. Modeling efforts have been performed to confirm that jarosite has the ability to incorporate a variety of "foreign" cations. The minerals unique ability to incorporate various large ions in its structure and its association with biological activity in terrestrial environments has lead to investigations regarding its use as an indicator of aqueous and/or biological activity. The use of laser desorption Fourier transform mass spectrometry (LD-FTMS) has revealed the presence of organic matter including the amino acid, glycine, in several jarosite samples from various worldwide locations. Iron precipitates derived from acidophilic microbial cultures were also analyzed. Using attenuated total reflectance infrared spectroscopy (ATR-IR), signals indicative of microbes or microbial exudates were weak and ambiguous. In contrast, LD-FTMS clearly detected bioorganic constituents in some desorption spots. However, the signals were sporadic and required the laser scanning/imaging capability of our laboratory built system to locate the microbial signatures in the heterogeneous samples. The ability to observe these bioorganic signatures in jarosite samples using the instrumental technique employed in this study furthers the goals of planetary geologists to determine whether signs of life (e.g., presence of biomolecules or biomolecule precursors) can be detected in the rock record of terrestrial and extraterrestrial samples.

  19. Modeling of Irradiation Hardening of Polycrystalline Materials

    SciTech Connect

    Li, Dongsheng; Zbib, Hussein M.; Garmestani, Hamid; Sun, Xin; Khaleel, Mohammad A.

    2011-09-14

    High energy particle irradiation of structural polycrystalline materials usually produces irradiation hardening and embrittlement. The development of predict capability for the influence of irradiation on mechanical behavior is very important in materials design for next generation reactors. In this work a multiscale approach was implemented to predict irradiation hardening of body centered cubic (bcc) alpha-iron. The effect of defect density, texture and grain boundary was investigated. In the microscale, dislocation dynamics models were used to predict the critical resolved shear stress from the evolution of local dislocation and defects. In the macroscale, a viscoplastic self-consistent model was applied to predict the irradiation hardening in samples with changes in texture and grain boundary. This multiscale modeling can guide performance evaluation of structural materials used in next generation nuclear reactors.

  20. Modeling of anisotropic hardening of sheet metals

    NASA Astrophysics Data System (ADS)

    Yoshida, Fusahito; Hamasaki, Hiroshi; Uemori, Takeshi

    2013-12-01

    To describe the evolution of anisotropy of sheet metals, in terms of both r-values and stresses, the present paper proposes anisotropic hardening models, where the shape of yield surface changes with increasing plastic strain. In this framework of modeling, any types of yield functions are able to be used. The evolution of anisotropy is expressed by updating the yield function as an interpolation between two yield functions defined at two different effective plastic strains. In this paper, two types of interpolation models, i.e., nonlinear interpolation model and piecewise interpolation model are presented. These models are validated by comparing the experimental data on 3003-O aluminum sheet (after Hu, Int J Plasticity 23, 620-639, 2007). To describe the Bauschinger effect, the combined anisotropic-kinematic hardening model is formulated based on Yoshida-Uemori kinematic hardening model.

  1. Photochemical transformations and laser flash photolysis studies of dibenzobarrelenes containing 1,2-dibenzoylalkene moieties

    SciTech Connect

    Kumar, C.V.; Murty, B.A.R.C.; Lahiri, S.; Chackachery, E.; Scaiano, J.C.; George, M.V.

    1984-12-14

    Phototransformations of the dibenzobarrelenes 10 = 11,12-dibenzoyl-9,10-dihydro-9,10-ethenoanthracene, 11 = 11,12-dibenzoyl-9,10-dihydro-9-methyl-9,10-ethenoanthracene, 23 = 11,12-dibenzoyl-9,10-dihydro-9,10-dimethyl-9,10-ethenoenthracene, prepared by the reaction of the appropriate anthracenes with dibenzoylacetylenes, are reported. Irradiation of 10 and 11 in solvents such as benzene, methanol, and acetone gave the corresponding dibenzosemibullvalenes, 17 = 8c, 8d-dibenzoyl-4b,8b,8c,8d-tetrahydrodibenzo(a,f)cyclopropa(c,d)- and 18, respectively, in good yields. These dibenzosemibullvalenes on catalytic hydrogenation using 5% Pd on charcoal gave the corresponding cyclopropane ring-opened products, 21 and 22, respectively. Irradiation of 23 in benzene gave a mixture of 2,3-dibenzoyl-2,3-dihydro-1,4-dimethyl-2,3-benzonaphthalene 27 (2%), 1,4-dibenzoyl-5,8-dimethyl-2,3:6,7-dibenzocyclo-octatetraene (24, 20%), the carbinol (45%), and benzoic acid (7%). Irradiation of 23 in methanol gave a mixture of 27 (25%), 24 (27%), and benzoic acid (8%). Laser flash photolysis (337.1 nm) of 10, 11, and 23 led to transient species, characterized by strong absorptions in the 300-650-nm region. These transients are due to the triplet states of the substrates, as established by quenching studies involving oxygen, di-tert-butylnitroxide, azulene, and ..beta..-carotene. Energy-transfer sensitization of 10, 11, and 23 by benzophenone in benzene also gave rise to the same transients, as formed under direct irradiation. The quantum yields of triplet formation (PHI/sub T/) were estimated to be high for 10 and 11 (approx. 1), whereas it is significantly lower for 23 (approx. 0.7). 24 references, 3 figures, 2 tables.

  2. Phenomenological modeling of hardening and thermal recovery in metals

    NASA Technical Reports Server (NTRS)

    Chan, K. S.; Lindholm, U. S.; Bodner, S. R.

    1988-01-01

    Modeling of hardening and thermal recovery in metals is considered within the context of unified elastic-viscoplastic theories. Specifically, the choices of internal variables and hardening measures, and the resulting hardening response obtained by incorporating saturation-type evolution equations into two general forms of the flow law are examined. Based on the analytical considerations, a procedure for delineating directional and isotropic hardening from uniaxial hardening data has been developed for the Bodner-Partom model and applied to a nickel-base superalloy, B1900 + Hf. Predictions based on the directional hardening properties deduced from the monotonic loading data are shown to be in good agreement with results of cyclic tests.

  3. Laser-induced fluorescence of Ba+ ions trapped and mass-selected in a Fourier transform ion cyclotron resonance mass spectrometer.

    PubMed

    Li, G Z; Vining, B A; Guan, S; Marshall, A G

    1996-01-01

    We present the design and preliminary results from a Fourier transform ion cyclotron resonance (ICR) mass spectrometer developed for the direct detection of UV/visible laser-induced fluorescence of trapped, mass-selected, gas-phase ions. A 3 T superconducting magnet and an open-ended multi-section cylindrical Penning trap capture and confine ions created by electron impact or laser desorption. Azimuthal quadrupolar excitation in the presence of ion/neutral collisions cools, axializes and mass selects ions as they fill the trap. A pulsed dye laser pumped by an Nd:YAG laser provides electronic energy excitation. A Brewster window and baffles on each side of the vacuum chamber reduce the scattered light from the excitation laser. Laser-induced fluorescence is collected from mirrors and lenses and directed through a quartz window and fiber-optic bundle to a photomultiplier. The ICR and optical events are controlled by a modular ICR data station and GPIB and RS-232 interfaces. An excitation spectrum is demonstrated for atomic Ba+ ions, and should extend to laser-induced fluorescence of virtually any stable positive or negative gas-phase ions of arbitrary molecular weight: molecular or quasimolecular ions, fragment ions, adduct ions, and ions formed from ion/molecule reactions. PMID:8953788

  4. Temperature-sensitive junction transformations for mid-wavelength HgCdTe photovoltaic infrared detector arrays by laser beam induced current microscope

    SciTech Connect

    Qiu, Weicheng; Hu, Weida Lin, Tie; Yin, Fei; Zhang, Bo; Chen, Xiaoshuang; Lu, Wei; Cheng, Xiang'ai Wang, Rui

    2014-11-10

    In this paper, we report on the disappearance of the photosensitive area extension effect and the unusual temperature dependence of junction transformation for mid-wavelength, n-on-p HgCdTe photovoltaic infrared detector arrays. The n-type region is formed by B{sup +} ion implantation on Hg-vacancy-doped p-type HgCdTe. Junction transformations under different temperatures are visually captured by a laser beam induced current microscope. A physical model of temperature dependence on junction transformation is proposed and demonstrated by using numerical simulations. It is shown that Hg-interstitial diffusion and temperature activated defects jointly lead to the p-n junction transformation dependence on temperature, and the weaker mixed conduction compared with long-wavelength HgCdTe photodiode contributes to the disappearance of the photosensitive area extension effect in mid-wavelength HgCdTe infrared detector arrays.

  5. Thermoelastic constitutive equations for chemically hardening materials

    NASA Technical Reports Server (NTRS)

    Shaffer, B. W.; Levitsky, M.

    1974-01-01

    Thermoelastic constitutive equations are derived for a material undergoing solidification or hardening as the result of a chemical reaction. The derivation is based upon a two component model whose composition is determined by the degree of hardening, and makes use of strain-energy considerations. Constitutive equations take the form of stress rate-strain rate relations, in which the coefficients are time-dependent functions of the composition. Specific results are developed for the case of a material of constant bulk modulus which undergoes a transition from an initial liquidlike state into an isotropic elastic solid. Potential applications are discussed.

  6. 'Work-Hardenable' Ductile Bulk Metallic Glass

    SciTech Connect

    Das, Jayanta; Eckert, Juergen; Tang Meibo; Wang Weihua; Kim, Ki Buem; Baier, Falko; Theissmann, Ralf

    2005-05-27

    Usually, monolithic bulk metallic glasses undergo inhomogeneous plastic deformation and exhibit poor ductility (<1%) at room temperature. We present a new class of bulk metallic glass, which exhibits high strength of up to 2265 MPa together with extensive 'work hardening' and large ductility of 18%. Significant increase in the flow stress was observed during deformation. The 'work-hardening' capability and ductility of this class of metallic glass is attributed to a unique structure correlated with atomic-scale inhomogeneity, leading to an inherent capability of extensive shear band formation, interactions, and multiplication of shear bands.

  7. Radiation Hardened Electronics for Space Environments (RHESE)

    NASA Technical Reports Server (NTRS)

    Keys, Andrew S.; Adams, James H.; Frazier, Donald O.; Patrick, Marshall C.; Watson, Michael D.; Johnson, Michael A.; Cressler, John D.; Kolawa, Elizabeth A.

    2007-01-01

    Radiation Environmental Modeling is crucial to proper predictive modeling and electronic response to the radiation environment. When compared to on-orbit data, CREME96 has been shown to be inaccurate in predicting the radiation environment. The NEDD bases much of its radiation environment data on CREME96 output. Close coordination and partnership with DoD radiation-hardened efforts will result in leveraged - not duplicated or independently developed - technology capabilities of: a) Radiation-hardened, reconfigurable FPGA-based electronics; and b) High Performance Processors (NOT duplication or independent development).

  8. Fuzzy Logic Classification of Imaging Laser Desorption Fourier Transform Mass Spectrometry Data

    SciTech Connect

    Timothy R. McJunkin; Jill R. Scott

    2008-06-01

    The fuzzy logic method is applied to classification of mass spectra obtained with an imaging internal source Fourier transform mass spectrometer (I2LD-FTMS). Traditionally, an operator uses the relative abundance of ions with specific mass-to-charge (m/z) ratios to categorize spectra. An operator does this by comparing the spectrum of m/z versus abundance of an unknown sample against a library of spectra from known samples. Automated positioning and acquisition allow the I2LD-FTMS to acquire data from very large grids, which would require classification of up to 3600 spectra per hour to keep pace with the acquisition. The tedious job of classifying numerous spectra generated in an I2LD-FTMS imaging application can be replaced by a fuzzy rule base if the cues an operator uses can be encapsulated. Appropriate methods for assigning fuzzy membership values for inputs (e.g., mass spectrum abundances) and choice of fuzzy inference operators to translate linguistic antecedent into confidence values for the consequence (or in this case the classification) is followed by using the maximum confidence and a necessary minimum threshold for making a crisp decision. This paper also describes a method for gathering statistics on ions, which are not currently used in the rule base, but which may be candidates for making the rule base more accurate and complete or to form new rule bases based on data obtained from known samples. A spatial method for classifying spectra with low membership values, based on neighboring sample classifications, is also presented.

  9. idRHa+ProMod - Rail Hardening Control System

    NASA Astrophysics Data System (ADS)

    Ferro, L.

    2016-03-01

    idRHa+ProMod is the process control system developed by Primetals Technologies to foresee the thermo-mechanical evolution and micro-structural composition of rail steels subjected to slack quenching into idRHa+ Rail Hardening equipments in a simulation environment. This tool can be used both off-line or in-line, giving the user the chance to test and study the best cooling strategies or letting the automatic control system free to adjust the proper cooling recipe. Optimization criteria have been tailored in order to determine the best cooling conditions according to the metallurgical requirements imposed by the main rail standards and also taking into account the elastoplastic bending phenomena occurring during all stages of the head hardening process. The computational core of idRHa+ProMod is a thermal finite element procedure coupled with special algorithms developed to work out the main thermo-physical properties of steel, to predict the non-isothermal austenite decomposition into all the relevant phases and subsequently to evaluate the amount of latent heat of transformation released, the compound thermal expansion coefficient and the amount of plastic deformation in the material. Air mist and air blades boundary conditions have been carefully investigated by means of pilot plant tests aimed to study the jet impingement on rail surfaces and the cooling efficiency at all working conditions. Heat transfer coefficients have been further checked and adjusted directly on field during commissioning. idRHa+ is a trademark of Primetals Technologies Italy Srl

  10. Comparison between Hilbert Huang transform and scalogram methods on non-stationary biomedical signals: application to laser Doppler flowmetry recordings

    NASA Astrophysics Data System (ADS)

    Roulier, Rémy; Humeau, Anne; Flatley, Thomas P.; Abraham, Pierre

    2005-11-01

    A significant transient increase in laser Doppler flowmetry (LDF) signals is observed in response to a local and progressive cutaneous pressure application on healthy subjects. This reflex may be impaired in diabetic patients. The work presents a comparison between two signal processing methods that provide a clarification of this phenomenon. Analyses by the scalogram and the Hilbert-Huang transform (HHT) of LDF signals recorded at rest and during a local and progressive cutaneous pressure application are performed on healthy and type 1 diabetic subjects. Three frequency bands, corresponding to myogenic, neurogenic and endothelial related metabolic activities, are studied at different time intervals in order to take into account the dynamics of the phenomenon. The results show that both the scalogram and the HHT methods lead to the same conclusions concerning the comparisons of the myogenic, neurogenic and endothelial related metabolic activities—during the progressive pressure and at rest—in healthy and diabetic subjects. However, the HHT shows more details that may be obscured by the scalogram. Indeed, the non-locally adaptative limitations of the scalogram can remove some definition from the data. These results may improve knowledge on the above-mentioned reflex as well as on non-stationary biomedical signal processing methods.

  11. Glycine Identification in Natural Jarosites Using Laser Desorption Fourier Transform Mass Spectrometry: Implications for the Search for Life on Mars

    NASA Astrophysics Data System (ADS)

    Kotler, J. Michelle; Hinman, Nancy W.; Yan, Beizhan; Stoner, Daphne L.; Scott, Jill R.

    2008-04-01

    The jarosite group minerals have received increasing attention since the discovery of jarosite on the martian surface by the Mars Exploration Rover Opportunity. Given that jarosite can incorporate foreign ions within its structure, we have investigated the use of jarosite as an indicator of aqueous and biological processes on Earth and Mars. The use of laser desorption Fourier transform mass spectrometry has revealed the presence of organic matter in several jarosite samples from various locations worldwide. One of the ions from the natural jarosites has been attributed to glycine because it was systematically observed in combinations of glycine with synthetic ammonium and potassium jarosites, Na2SO4 and K2SO4. The ability to observe these organic signatures in jarosite samples with an in situ instrumental technique, such as the one employed in this study, furthers the goals of planetary geologists to determine whether signs of life (e.g., the presence of biomolecules or biomolecule precursors) can be detected in the rock record of terrestrial and extraterrestrial samples.

  12. Laser vision: lidar as a transformative tool to advance critical zone science

    NASA Astrophysics Data System (ADS)

    Harpold, A. A.; Marshall, J. A.; Lyon, S. W.; Barnhart, T. B.; Fisher, B. A.; Donovan, M.; Brubaker, K. M.; Crosby, C. J.; Glenn, N. F.; Glennie, C. L.; Kirchner, P. B.; Lam, N.; Mankoff, K. D.; McCreight, J. L.; Molotch, N. P.; Musselman, K. N.; Pelletier, J.; Russo, T.; Sangireddy, H.; Sjöberg, Y.; Swetnam, T.; West, N.

    2015-06-01

    Observation and quantification of the Earth's surface is undergoing a revolutionary change due to the increased spatial resolution and extent afforded by light detection and ranging (lidar) technology. As a consequence, lidar-derived information has led to fundamental discoveries within the individual disciplines of geomorphology, hydrology, and ecology. These disciplines form the cornerstones of critical zone (CZ) science, where researchers study how interactions among the geosphere, hydrosphere, and biosphere shape and maintain the "zone of life", which extends from the top of unweathered bedrock to the top of the vegetation canopy. Fundamental to CZ science is the development of transdisciplinary theories and tools that transcend disciplines and inform other's work, capture new levels of complexity, and create new intellectual outcomes and spaces. Researchers are just beginning to use lidar data sets to answer synergistic, transdisciplinary questions in CZ science, such as how CZ processes co-evolve over long timescales and interact over shorter timescales to create thresholds, shifts in states and fluxes of water, energy, and carbon. The objective of this review is to elucidate the transformative potential of lidar for CZ science to simultaneously allow for quantification of topographic, vegetative, and hydrological processes. A review of 147 peer-reviewed lidar studies highlights a lack of lidar applications for CZ studies as 38 % of the studies were focused in geomorphology, 18 % in hydrology, 32 % in ecology, and the remaining 12 % had an interdisciplinary focus. A handful of exemplar transdisciplinary studies demonstrate lidar data sets that are well-integrated with other observations can lead to fundamental advances in CZ science, such as identification of feedbacks between hydrological and ecological processes over hillslope scales and the synergistic co-evolution of landscape-scale CZ structure due to interactions amongst carbon, energy, and water cycles

  13. Irradiation hardening of reduced activation martensitic steels

    NASA Astrophysics Data System (ADS)

    Kimura, A.; Morimura, T.; Narui, M.; Matsui, H.

    1996-10-01

    Irradiation response on the tensile properties of 9Cr2W steels has been investigated following FFTF/MOTA irradiations at temperatures between 646 and 873 K up to doses between 10 and 59 dpa. The largest irradiation hardening accompanied by the largest decrease in the elongation is observed for the specimens irradiated at 646 K at doses between 10 and 15 dpa. The irradiation hardening appears to saturate at a dose of around 10 dpa at the irradiation temperature. No hardening but softening was observed in the specimens irradiated at above 703 K to doses of 40 and 59 dpa. Microstructural observation by transmission electron microscope (TEM) revealed that the dislocation loops with the a<100> type Burgers vector and small precipitates which were identified to be M 6C type carbides existed after the irradiation at below 703 K. As for the void formation, the average size of voids increased with increasing irradiation temperature from 646 to 703 K. No voids were observed above 703 K. Irradiation softening was attributed to the enhanced recovery of martensitic structure under the irradiation. Post-irradiation annealing resulted in hardening by the annealing at 673 K and softening by the annealing at 873 K.

  14. SEU hardening of CMOS memory circuit

    NASA Technical Reports Server (NTRS)

    Whitaker, S.; Canaris, J.; Liu, K.

    1990-01-01

    This paper reports a design technique to harden CMOS memory circuits against Single Event Upset (SEU) in the space environment. A RAM cell and Flip Flop design are presented to demonstrate the method. The Flip Flop was used in the control circuitry for a Reed Solomon encoder designed for the Space Station.

  15. Extraordinary strain hardening by gradient structure

    PubMed Central

    Wu, XiaoLei; Jiang, Ping; Chen, Liu; Yuan, Fuping; Zhu, Yuntian T.

    2014-01-01

    Gradient structures have evolved over millions of years through natural selection and optimization in many biological systems such as bones and plant stems, where the structures change gradually from the surface to interior. The advantage of gradient structures is their maximization of physical and mechanical performance while minimizing material cost. Here we report that the gradient structure in engineering materials such as metals renders a unique extra strain hardening, which leads to high ductility. The grain-size gradient under uniaxial tension induces a macroscopic strain gradient and converts the applied uniaxial stress to multiaxial stresses due to the evolution of incompatible deformation along the gradient depth. Thereby the accumulation and interaction of dislocations are promoted, resulting in an extra strain hardening and an obvious strain hardening rate up-turn. Such extraordinary strain hardening, which is inherent to gradient structures and does not exist in homogeneous materials, provides a hitherto unknown strategy to develop strong and ductile materials by architecting heterogeneous nanostructures. PMID:24799688

  16. Detection of polychlorinated biphenyls in transformer oils in Vietnam by multiphoton ionization mass spectrometry using a far-ultraviolet femtosecond laser as an ionization source.

    PubMed

    Vu, Thi Thuy Duong; Vu, Duong; Nghiem, Thi Ha Lien; Imasaka, Tomoko; Tang, Yuanyuan; Shibuta, Shinpei; Hamachi, Akifumi; Do, Quang Hoa; Imasaka, Totaro

    2016-03-01

    Polychlorinated biphenyls (PCBs) in transformer and food oils were measured using gas chromatography combined with multiphoton ionization mass spectroscopy. An ultrashort laser pulse emitting in the far-ultraviolet region was utilized for efficient ionization of the analytes. Numerous signal peaks were clearly observed for a standard sample mixture of PCBs when the third and fourth harmonic emissions (267 and 200nm) of a femtosecond Ti:sapphire laser (800nm) were employed. The signal intensities were found to be greater when measured at 200nm compared with those measured at 267nm, providing lower detection limits especially for highly chlorinated PCBs at shorter wavelengths. After simple pretreatment using disposable columns, PCB congeners were measured and found to be present in the transformer oils used in Vietnam. PMID:26717841

  17. 'Fire hardening' spear wood does slightly harden it, but makes it much weaker and more brittle.

    PubMed

    Ennos, Antony Roland; Chan, Tak Lok

    2016-05-01

    It is usually assumed that 'fire hardening' the tips of spears, as practised by hunter-gatherers and early Homo spp., makes them harder and better suited for hunting. This suggestion was tested by subjecting coppiced poles of hazel to a fire-hardening process and comparing their mechanical properties to those of naturally seasoned poles. A Shore D hardness test showed that fire treatment slightly increased the hardness of the wood, but flexural and impact tests showed that it reduced the strength and work of fracture by 30% and 36%, respectively. These results suggest that though potentially slightly sharper and more durable, fire-hardened tips would actually be more likely to break off when used, as may have been the case with the earliest known wooden tool, the Clacton spear. Fire might first have been used to help sharpen the tips of spears, and fire-hardening would have been a mostly negative side effect, not its primary purpose. PMID:27194289

  18. UV laser ablation of GdCa4O(BO3)3 (GdCOB) investigated by Fourier transform ion cyclotron resonance mass spectrometry.

    PubMed

    Chéty-Gimondo, Rachel; Aubriet, Frédéric; Millon, Eric; Muller, J-F

    2004-01-01

    The ions generated by laser ablation (LA) of calcium and gadolinium oxoborate GdCa4O(BO3)3 (GdCOB) were investigated by Fourier transform ion cyclotron resonance mass spectrometry (FTICRMS), a powerful tool for the characterization of ionic species produced by laser interaction with solid material. In order to better understand the matter transfer and the mechanism of thin film growth by pulsed-laser deposition (PLD), cationic and anionic clusters generated by UV laser ablation of GdCOB bulk material were studied. Laser ablation of GdCOB leads to the formation of various cluster ions which result from association of CaO, BO and B2O3 building blocks (BB) with different charge carriers (CC): H+, BO+, GdO+ in positive ion mode, and BO2-, OK-, OH-, Cl-, WO3- in negative ion mode. LA-FTICRMS investigations allow us to assign a valence state to each metallic atom included in each BB. A +II chemical state may be associated with calcium and +II and +III ones to boron. UV laser ablation of GdCOB therefore induces reduction processes of boron species in the gas phase. The oxygen reactive atmosphere used during PLD experiments allows the growth of stoichiometric thin films by fixation of oxygen on the ablated species. PMID:15529417

  19. Deformation in metals after low temperature irradiation: Part II - Irradiation hardening, strain hardening, and stress ratios

    SciTech Connect

    Byun, Thak Sang; Li, Meimei

    2008-03-01

    Effects of irradiation at temperatures 200oC on tensile stress parameters are analyzed for dozens of bcc, fcc, and hcp pure metals and alloys, focusing on irradiation hardening, strain hardening, and relationships between the true stress parameters. Similar irradiation-hardening rates are observed for all the metals irrespective of crystal type; typically, the irradiation-hardening rates are large, in the range 100 - 1000 GPa/dpa, at the lowest dose of <0.0001 dpa and decrease with dose to a few tens of MPa/dpa or less at about 10 dpa. However, average irradiation-hardening rates over the dose range of 0 dpa − (the dose to plastic instability at yield) are considerably lower for stainless steels due to their high uniform ductility. It is shown that whereas low temperature irradiation increases the yield stress, it does not significantly change the strain-hardening rate of metallic materials; it decreases the fracture stress only when non-ductile failure occurs. Such dose independence in strain hardening behavior results in strong linear relationships between the true stress parameters. Average ratios of plastic instability stress to unirradiated yield stress are about 1.4, 3.9, and 1.3 for bcc metals (and precipitation hardened IN718 alloy), annealed fcc metals (and pure Zr), and Zr-4 alloy, respectively. Ratios of fracture stress to plastic instability stress are calculated to be 2.2, 1.7, and 2.1, respectively. Comparison of these values confirms that the annealed fcc metals and other soft metals have larger uniform ductility but smaller necking ductility when compared to other materials.

  20. 7 CFR 58.622 - Hardening and storage rooms.

    Code of Federal Regulations, 2012 CFR

    2012-01-01

    ... 7 Agriculture 3 2012-01-01 2012-01-01 false Hardening and storage rooms. 58.622 Section 58.622 Agriculture Regulations of the Department of Agriculture (Continued) AGRICULTURAL MARKETING SERVICE (Standards....622 Hardening and storage rooms. Hardening and storage rooms for frozen desserts shall be...

  1. 7 CFR 58.622 - Hardening and storage rooms.

    Code of Federal Regulations, 2013 CFR

    2013-01-01

    ... 7 Agriculture 3 2013-01-01 2013-01-01 false Hardening and storage rooms. 58.622 Section 58.622 Agriculture Regulations of the Department of Agriculture (Continued) AGRICULTURAL MARKETING SERVICE (Standards....622 Hardening and storage rooms. Hardening and storage rooms for frozen desserts shall be...

  2. 7 CFR 58.622 - Hardening and storage rooms.

    Code of Federal Regulations, 2014 CFR

    2014-01-01

    ... 7 Agriculture 3 2014-01-01 2014-01-01 false Hardening and storage rooms. 58.622 Section 58.622 Agriculture Regulations of the Department of Agriculture (Continued) AGRICULTURAL MARKETING SERVICE (Standards....622 Hardening and storage rooms. Hardening and storage rooms for frozen desserts shall be...

  3. 7 CFR 58.622 - Hardening and storage rooms.

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    ... 7 Agriculture 3 2010-01-01 2010-01-01 false Hardening and storage rooms. 58.622 Section 58.622 Agriculture Regulations of the Department of Agriculture (Continued) AGRICULTURAL MARKETING SERVICE (Standards....622 Hardening and storage rooms. Hardening and storage rooms for frozen desserts shall be...

  4. 7 CFR 58.622 - Hardening and storage rooms.

    Code of Federal Regulations, 2011 CFR

    2011-01-01

    ... 7 Agriculture 3 2011-01-01 2011-01-01 false Hardening and storage rooms. 58.622 Section 58.622 Agriculture Regulations of the Department of Agriculture (Continued) AGRICULTURAL MARKETING SERVICE (Standards....622 Hardening and storage rooms. Hardening and storage rooms for frozen desserts shall be...

  5. Photoacoustic spectroscopy detection and extraction of discharge feature gases in transformer oil based on 1.5 μ tunable fiber laser

    NASA Astrophysics Data System (ADS)

    Wu, Zhiying; gong, Yinhai; Yu, Qingxu

    2013-05-01

    Information from the analysis of gasses dissolved in insulating oils is valuable for early a transformer maintenance. By means of dissolved gas analysis (DGA), it is possible to distinguish faults such as partial discharge (corona), overheating (pyrolysis) and arcing in a great variety of oil-filled equipment. Tunable fiber laser-based second harmonic photoacoustic spectroscopy offers a fast and good-noise-immunity technique for the quantitative analysis of trace gases in transformer oil. In this work, the discharge feature gases, such as C2H2, CH4, CO2 and H2O, were measured with a tunable laser photoacoustic spectrometer at the 1530.3709 nm transition line, as a typical application of precise measurement of multi-gas, a proposed BSS model based on overcomplete ICA basis and five-point-sampling method based on a created weight-truncation-constraint equation was used to remove noise so that several fault gases can be extracted with a higher detection accuracy and a method detection limit. Experiment shows that within 0.15 nm band near 1530.3709 nm, the four-gas contents have been detected and extracted and the detection accuracy has been improved from available scanning spacing of 0.03 nm to available extracting spacing of 0.0011 nm. At room temperature and atmospheric pressure, this can achieve simultaneous detection for multiple feature gases in discharged transformer oil using laser source with a limited waveband.

  6. Transformation of medical grade silicone rubber under Nd:YAG and excimer laser irradiation: First step towards a new miniaturized nerve electrode fabrication process

    NASA Astrophysics Data System (ADS)

    Dupas-Bruzek, C.; Robbe, O.; Addad, A.; Turrell, S.; Derozier, D.

    2009-08-01

    Medical grade silicone rubber, poly-dimethylsiloxane (PDMS) is a widely used biomaterial. Like for many polymers, its surface can be modified in order to change one or several of its properties which further allow this surface to be functionalized. Laser-induced surface modification of PDMS under ambient conditions is an easy and powerful method for the surface modification of PDMS without altering its bulk properties. In particular, we profit from both UV laser inducing surface modification and of UV laser micromachining to develop a first part of a new process aiming at increasing the number of contacts and tracks within the same electrode surface to improve the nerve selectivity of implantable self sizing spiral cuff electrodes. The second and last part of the process is to further immerse the engraved electrode in an autocatalytic Pt bath leading in a selective Pt metallization of the laser irradiated tracks and contacts and thus to a functionalized PDMS surface. In the present work, we describe the different physical and chemical transformations of a medical grade PDMS as a function of the UV laser and of the irradiation conditions used. We show that the ablation depths, chemical composition, structure and morphology vary with (i) the laser wavelength (using an excimer laser at 248 nm and a frequency-quadrupled Nd:YAG laser at 266 nm), (ii) the conditions of irradiation and (iii) the pulse duration. These different modified properties are expected to have a strong influence on the nucleation and growth rates of platinum which govern the adhesion and the thickness of the Pt layer on the electrodes and thus the DC resistance of tracks.

  7. Design and Characterization of a High-power Laser-induced Acoustic Desorption (LIAD) Probe Coupled with a Fourier-transform Ion Cyclotron Resonance Mass Spectrometer

    PubMed Central

    Shea, Ryan C.; Habicht, Steven C.; Vaughn, Weldon E.; Kenttämaa, Hilkka I.

    2008-01-01

    We report here the construction and characterization of a high-power laser-induced acoustic desorption (LIAD) probe designed for Fourier-transform ion cyclotron resonance (FT-ICR) mass spectrometers to facilitate analysis of non-volatile, thermally labile compounds. This “next generation” LIAD probe offers significant improvements in sensitivity and desorption efficiency for analytes with larger molecular weights via the use of higher laser irradiances. Unlike the previous probes which utilized a power limiting optical fiber to transmit the laser pulses through the probe, this probe employs a set of mirrors and a focusing lens. At the end of the probe, the energy from the laser pulses propagates through a thin metal foil as an acoustic wave, resulting in desorption of neutral molecules from the opposite side of the foil. Following desorption, the molecules can be ionized by electron impact or chemical ionization. Almost an order of magnitude greater power density (up to 5.0 × 109 W/cm2) is achievable on the backside of the foil with the high-power LIAD probe compared to the earlier LIAD probes (maximum power density ~9.0 × 108 W/cm2). The use of higher laser irradiances is demonstrated not to cause fragmentation of the analyte. The use of higher laser irradiances increases sensitivity since it results in the evaporation of a greater number of molecules per laser pulse. Measurement of the average velocities of LIAD evaporated molecules demonstrates that higher laser irradiances do not correlate with higher velocities of the gaseous analyte molecules. PMID:17319645

  8. Influence of Post-Weld Annealing on Transformation Behavior and Mechanical Properties of Laser-Welded NiTi Alloy Wires

    NASA Astrophysics Data System (ADS)

    Yan, Xiaojun; Ge, Yuli

    2014-10-01

    The influence of annealing on the transformation behavior, mechanical, and functional properties of laser-welded NiTi wires was investigated. The results show that Ti3Ni4 precipitates occur after post-weld annealing and coarsen with increasing annealing temperature. The as-welded specimen exhibits one-step B2 → B19' transformation, while the annealed ones show two-step B2 → R → B19' transformation. Annealing at 400 °C for 1 h can improve the tensile strength and superelasticity of the welded joints. However, these properties decrease when annealing at 500 °C for 1 h. The change of mechanical and functional properties after annealing is attributed to the different size of Ti3Ni4 precipitates. Annealing to produce smaller coherent precipitates (10 nm) improves the mechanical and functional properties of the welded joints. As the Ti3Ni4 precipitates coarsen, the mechanical and functional properties decrease.

  9. Transform-limited pulse generation in the gigahertz region from a gain-switched distributed-feedback laser diode using spectral windowing.

    PubMed

    Nakazawa, M; Suzuki, K; Kimura, Y

    1990-06-15

    For the first time, to our knowledge, transform-limited and high-power picosecond pulses in the gigahertz region are successfully generated from a distributed-feedback laser diode using spectral manipulation with a narrow-band Fabry-Perot resonator and erbium fiber amplifiers. The pulses, which before the optical filtering have a width of 27 psec and a spectral width of 1.24 nm, are transformed to transform-limited pulses with a width of 17 psec and a spectral width of 0.21 nm. The peak power of the pulse at a 6-GHz repetition rate is amplified to greater than 90 mW with an erbium fiber amplifier. PMID:19768057

  10. Laser irradiation-induced {alpha} to {delta} phase transformation in Bi{sub 2}O{sub 3} ceramics and nanowires

    SciTech Connect

    Vila, M.; Diaz-Guerra, C.; Piqueras, J.

    2012-08-13

    The {alpha}-Bi{sub 2}O{sub 3} to {delta}-Bi{sub 2}O{sub 3} phase transformation has been locally induced by laser irradiation in ceramic samples and single-crystal nanowires of this oxide. The threshold power densities necessary to induce this transformation, as well as the corresponding transformation kinetics and its temporal stability, have been investigated in both kinds of samples by micro-Raman spectroscopy. The appearance of the {delta} phase was also monitored by spatially resolved photoluminescence spectroscopy. An emission band peaked near 1.67 eV, not observed in {alpha}-Bi{sub 2}O{sub 3}, is tentatively attributed to {delta}-Bi{sub 2}O{sub 3} near band gap transitions.

  11. Mechanisms of formation of hardening precipitates and hardening in aging of Al-Li-Cu-Mg model alloys with silver additions

    NASA Astrophysics Data System (ADS)

    Alekseev, A. A.; Zhuravleva, P. L.; Onuchina, M. R.; Klochkova, Yu. Yu.

    2015-11-01

    The mechanisms of the influence of silver additions on the phase transformations that occur in aging are revealed. The contribution of Ω'-phase particles to the deformation stress in Al alloys is estimated. The mechanisms of the effect of low (up to 0.5 wt %) silver additions and the copper content on the structure of the Ω'-phase precipitates in Al alloys are found. According to the proposed model, silver atoms remain immobile during the decomposition of a solid solution and nucleation centers of the Ω' phase form near them in low-temperature aging. Upon hardening aging, fragmented Ω'-phase particles intersect with each other, and the contribution of the intersection regions to the hardening of alloys by Ω'-phase particles is principal.

  12. Revealing cyclic hardening mechanism of a TRIP steel by real-time in situ neutron diffraction

    SciTech Connect

    Yu, Dunji; An, Ke; Chen, Yan; Chen, Xu

    2014-01-01

    Real-time in situ neutron diffraction was performed on a transformation-induced plasticity (TRIP) steel under cyclic loading at room temperature. By Rietveld refinement and single peak analysis, the volume fraction and average stress estimates as well as dislocation density of individual phases (austenite and martensite phase) were derived. The results reveal that the volume fraction of martensite phase, instead of individual phase strengthening, should be accounted for the remarkable secondary cyclic hardening.

  13. Effectiveness of hardening threaded parts by plastic deformation

    SciTech Connect

    Pyshkin, V.A.; Belai, S.V.; Dyad'kova, I.G.

    1983-03-01

    The rules of hardening threaded parts by roller burning the root of the inner diameter of a thread are studied. The effectiveness of hardening increases where the allowance for the inner diameter increases. By equations, a change in the inner diameter can be used to determine the depth of work hardening residual compressive stress, fatigue limit, and the mechanical properties of the threaded part. The effective stress concentration factor, increase in transmission load, and average tensile stress in cyclic loading, are also calculated. Equations help to determine the depth of hardening necessary; the optimum conditions of burnishing; and the maximum increase in fatigue strength, with optimum hardening conditions.

  14. Beam hardening correction for X-ray computed tomography of heterogeneous natural materials

    NASA Astrophysics Data System (ADS)

    Ketcham, Richard A.; Hanna, Romy D.

    2014-06-01

    We present a new method for correcting beam hardening artifacts in polychromatic X-ray CT data. On most industrial CT systems, software beam-hardening correction employs some variety of linearization, which attempts to transform the polychromatic attenuation data into its monochromatic equivalent prior to image reconstruction. However, determining optimal coefficients for the transform equation is not straightforward, especially if the material is not well known or characterized, as is the usual case when imaging geological materials. Our method uses an iterative optimization algorithm to find a generalized spline-interpolated transform that minimizes artifacts as defined by an expert user. This generality accesses a richer set of linearization functions that may better accommodate the effects of multiple materials in heterogeneous samples. When multiple materials are present in the scan field, there is no single optimal correction, and the solution can vary depending on which aspects of the beam-hardening and other image artifacts the user wants to minimize. For example, the correction can be optimized to maximize the fidelity of the object outline for solid model creation rather than simply to minimize variation of CT numbers within the material. We demonstrate our method on a range of specimens of varying difficulty and complexity, with consistently positive results.

  15. Single Event Effects on Space Radiation Hardened 64K SRAMS at Room temperature

    NASA Technical Reports Server (NTRS)

    Kim, O.; Schwartz, H.; McCarty, K.; Coss, J.; Barnes, C.

    1993-01-01

    The laser threshold linear Energy transfer for single event upsetscan be estimaed, even at room temperature, for space radiation hardened 64K SRAMs. The memories where independently developed to quality for the Qualified Manufacturer's List by IBM and Honeywell. The memory was so hard that high energy heavy ions generated by the Van de Graff could not determine the SEU threshold at room temperature. Use of pulsed Laser tests would meake it possible to forgo very expensive testing at ultra-high energy accelerators.

  16. Construction procedures using self hardening fly ash

    NASA Astrophysics Data System (ADS)

    Thornton, S. I.; Parker, D. G.

    1980-07-01

    Fly ash produced in Arkansas from burning Wyoming low sulfur coal is self-hardening and can be effective as a soil stabilizing agent for clays and sands. The strength of soil-self hardening fly ash develops rapidly when compacted immediately after mixing. Seven day unconfined compressive strengths up to 1800 psi were obtained from 20% fly ash and 80% sand mixtures. A time delay between mixing the fly ash with the soil and compaction of the mixture reduced the strength. With two hours delay, over a third of the strength was lost and with four hours delay, the loss was over half. Gypsum and some commercial concrete retarders were effective in reducing the detrimental effect of delayed compaction. Adequate mixing of the soil and fly ash and rapid compaction of the mixtures were found to be important parameters in field construction of stabilized bases.

  17. Modeling the Case Hardening of Automotive Components

    NASA Astrophysics Data System (ADS)

    Munikamal, Tiruttani; Sundarraj, Suresh

    2013-04-01

    A generalized framework has been developed within ABAQUS to model the surface hardening heat treatment processes for automotive steel components. The macro-scale heat transfer and stress calculations during the heating and quenching are coupled with the microstructural phase calculations, defined through a user routine, to estimate key process parameters such as case depth and surface hardness. This model has been applied to predict these parameters in two key industrial processes, i.e., case hardening of crankshafts and case carburization of gears. The results of the case depth and hardness calculations have been validated with the literature and in-house plant data. The effect of varying quench conditions on the overall stress distribution changes within the component has been outlined.

  18. Radiation-hardened transistor and integrated circuit

    DOEpatents

    Ma, Kwok K.

    2007-11-20

    A composite transistor is disclosed for use in radiation hardening a CMOS IC formed on an SOI or bulk semiconductor substrate. The composite transistor has a circuit transistor and a blocking transistor connected in series with a common gate connection. A body terminal of the blocking transistor is connected only to a source terminal thereof, and to no other connection point. The blocking transistor acts to prevent a single-event transient (SET) occurring in the circuit transistor from being coupled outside the composite transistor. Similarly, when a SET occurs in the blocking transistor, the circuit transistor prevents the SET from being coupled outside the composite transistor. N-type and P-type composite transistors can be used for each and every transistor in the CMOS IC to radiation harden the IC, and can be used to form inverters and transmission gates which are the building blocks of CMOS ICs.

  19. Anomalous temperature dependence of yield stress and work hardening coefficient of B2-stabilized NiTi alloys

    SciTech Connect

    Hosoda, Hideki; Mishima, Yoshinao; Suzuki, Tomoo

    1997-12-31

    Yield stress and work hardening coefficient of B2-stabilized NiTi alloys are investigated using compression tests. Compositions of NiTi alloys are based on Ni-49mol.%Ti, to which Cr, Co and Al are chosen as ternary elements which reduce martensitic transformation temperatures of the B2 phase. Mechanical tests are carried out in liquid nitrogen at 77 K, air at room temperature (R.T.) and in an argon atmosphere between 473 K and 873 K. Only at 77 K, some alloys show characteristic stress-strain curves which indicate stress induced martensitic transformation (SIMT), but the others do not. Work hardening coefficient is found to be between 2 and 11GPa in all the test temperature range. The values are extremely high compared with Young`s modulus of B2 NiTi. Yield stress and work hardening coefficient increase with test temperature between R.T. and about 650 K in most alloys. The anomalous temperature dependence of mechanical properties is not related to SIMT but to precipitation hardening and/or anomalous dislocation motion similar to B2-type CoTi. Solution hardening by adding ternary elements is evaluated to be small for Cr and Co additions, and large for Al addition, depending on difference in atomic size of the ternary element with respect to Ni or Ti.

  20. Work hardening: occupational therapy in industrial rehabilitation.

    PubMed

    Matheson, L N; Ogden, L D; Violette, K; Schultz, K

    1985-05-01

    Work hardening, presented in this paper as a "new" service for the industrially injured, is actually well grounded in the traditional models and practices of occupational therapy. From the profession's early roots in industrial therapy to the development of a variety of programs for the industrially injured through the 1950s and 1960s, the historical and philosophical bases of occupational therapy support the use of work as an evaluative and therapeutic medium. What is actually new is the adoption of terminology, technology, and a program format that fits in with the needs of consumers in the 1980s. Recent developments that created the need for the specialized services that occupational therapists are uniquely qualified to provide include growth of private sector vocational rehabilitation, changes in workers' compensation laws, and increasing costs of vocational rehabilitation. This paper describes work hardening in its present form. A case example is given that demonstrates how work hardening can be a cost-effective and time-saving bridge which spans the gap between curative medicine and the return to work. PMID:4014411

  1. Dislocation Multi-junctions and Strain Hardening

    SciTech Connect

    Bulatov, V; Hsiung, L; Tang, M; Arsenlis, A; Bartelt, M; Cai, W; Florando, J; Hiratani, M; Rhee, M; Hommes, G; Pierce, T; Diaz de la Rubia, T

    2006-06-20

    At the microscopic scale, the strength of a crystal derives from the motion, multiplication and interaction of distinctive line defects--dislocations. First theorized in 1934 to explain low magnitudes of crystal strength observed experimentally, the existence of dislocations was confirmed only two decades later. Much of the research in dislocation physics has since focused on dislocation interactions and their role in strain hardening: a common phenomenon in which continued deformation increases a crystal's strength. The existing theory relates strain hardening to pair-wise dislocation reactions in which two intersecting dislocations form junctions tying dislocations together. Here we report that interactions among three dislocations result in the formation of unusual elements of dislocation network topology, termed hereafter multi-junctions. The existence of multi-junctions is first predicted by Dislocation Dynamics (DD) and atomistic simulations and then confirmed by the transmission electron microscopy (TEM) experiments in single crystal molybdenum. In large-scale Dislocation Dynamics simulations, multi-junctions present very strong, nearly indestructible, obstacles to dislocation motion and furnish new sources for dislocation multiplication thereby playing an essential role in the evolution of dislocation microstructure and strength of deforming crystals. Simulation analyses conclude that multi-junctions are responsible for the strong orientation dependence of strain hardening in BCC crystals.

  2. Stage IV work hardening in cubic metals

    SciTech Connect

    Rollett, A.D.; Kocks, U.F.; Doherty, R.D.

    1986-01-01

    The work hardening of fcc metals at large strains is discussed with reference to the linear stress-strain behavior often observed at large strains and known as Stage IV. The experimental evidence shows that Stage IV is a work hardening phenomenon that is found quite generally, even in pure fcc metals subjected to homogeneous deformation. A simple model for Stage IV in pure metals is presented, based on the accumulation of dislocation debris. Experiments are described for large strain torsion tests on four aluminum alloys. The level and extent of Stage IV scaled with the saturation stress that would represent the end of Stage III in the absence of a Stage IV. Reversing the torsion after large prestrains produced transient reductions in the work hardening. The strain rate sensitivity was also measured before and during the transient and found not to vary significantly. The microstructure observed at large strains in an Mg alloy suggest that Stage IV can occur in the absence of microband formation. Previous proposals for the cause of Stage IV are reviewed and found to be not supported by recent experimental data.

  3. Age-hardening associated with grain boundary precipitation in a commercial dental gold alloy.

    PubMed

    Kim, H I; Jang, M I; Kim, M S

    1999-03-01

    The aim of this study was to make clear the age-hardening mechanism in a dental high carat gold alloy. For this purpose, age-hardening behaviour of a commercial dental high carat gold alloy, 65.5 wt% Au-14.0 wt% Ag-10.0 wt% Cu-8.9 wt% Pt, was investigated by means of hardness testing, X-ray diffraction study and scanning electron microscopy. Age-hardening was generated by the coherency strain resulting from the transformation of the alpha single phase to the Ag-rich alpha 1 phase and the AuCu I type ordered phase. The coherency strain seemed to be associated with the nucleation of the AuCu ordered structure initially, and then was brought about with the simultaneous formation of the Ag-rich alpha 1 phase and the AuCu I type ordered phase. Hardening was attributed mainly to the very fine coherent precipitates of a lamellar structure composed of the Ag-rich alpha 1 phase and the AuCu I type ordered phase at grain boundaries, and softening, which occurred following prolonged ageing, was due to the coarsening of the fine lamellar structure by releasing the strain at the interfaces of the adjacent lamellae. PMID:10194730

  4. Laser-induced transformation of supramolecular complexes: approach to controlled formation of hybrid multi-yolk-shell Au-Ag@a-C:H nanostructures

    PubMed Central

    Manshina, A. A.; Grachova, E. V.; Povolotskiy, A. V.; Povolotckaia, A. V.; Petrov, Y. V.; Koshevoy, I. O.; Makarova, A. A.; Vyalikh, D. V.; Tunik, S. P.

    2015-01-01

    In the present work an efficient approach of the controlled formation of hybrid Au–Ag–C nanostructures based on laser-induced transformation of organometallic supramolecular cluster compound is suggested. Herein the one-step process of the laser-induced synthesis of hybrid multi-yolk-shell Au-Ag@a-C:H nanoparticles which are bimetallic gold-silver subnanoclusters dispersed in nanospheres of amorphous hydrogenated a-C:H carbon is reported in details. It has been demonstrated that variation of the experimental parameters such as type of the organometallic precursor, solvent, deposition geometry and duration of laser irradiation allows directed control of nanoparticles’ dimension and morphology. The mechanism of Au-Ag@a-C:H nanoparticles formation is suggested: the photo-excitation of the precursor molecule through metal-to-ligand charge transfer followed by rupture of metallophilic bonds, transformation of the cluster core including red-ox intramolecular reaction and aggregation of heterometallic species that results in the hybrid metal/carbon nanoparticles with multi-yolk-shell architecture formation. It has been found that the nanoparticles obtained can be efficiently used for the Surface-Enhanced Raman Spectroscopy label-free detection of human serum albumin in low concentration solution. PMID:26153347

  5. Laser-induced transformation of supramolecular complexes: approach to controlled formation of hybrid multi-yolk-shell Au-Ag@a-C:H nanostructures.

    PubMed

    Manshina, A A; Grachova, E V; Povolotskiy, A V; Povolotckaia, A V; Petrov, Y V; Koshevoy, I O; Makarova, A A; Vyalikh, D V; Tunik, S P

    2015-01-01

    In the present work an efficient approach of the controlled formation of hybrid Au-Ag-C nanostructures based on laser-induced transformation of organometallic supramolecular cluster compound is suggested. Herein the one-step process of the laser-induced synthesis of hybrid multi-yolk-shell Au-Ag@a-C:H nanoparticles which are bimetallic gold-silver subnanoclusters dispersed in nanospheres of amorphous hydrogenated a-C:H carbon is reported in details. It has been demonstrated that variation of the experimental parameters such as type of the organometallic precursor, solvent, deposition geometry and duration of laser irradiation allows directed control of nanoparticles' dimension and morphology. The mechanism of Au-Ag@a-C:H nanoparticles formation is suggested: the photo-excitation of the precursor molecule through metal-to-ligand charge transfer followed by rupture of metallophilic bonds, transformation of the cluster core including red-ox intramolecular reaction and aggregation of heterometallic species that results in the hybrid metal/carbon nanoparticles with multi-yolk-shell architecture formation. It has been found that the nanoparticles obtained can be efficiently used for the Surface-Enhanced Raman Spectroscopy label-free detection of human serum albumin in low concentration solution. PMID:26153347

  6. Empirical beam hardening correction (EBHC) for CT

    SciTech Connect

    Kyriakou, Yiannis; Meyer, Esther; Prell, Daniel; Kachelriess, Marc

    2010-10-15

    Purpose: Due to x-ray beam polychromaticity and scattered radiation, attenuation measurements tend to be underestimated. Cupping and beam hardening artifacts become apparent in the reconstructed CT images. If only one material such as water, for example, is present, these artifacts can be reduced by precorrecting the rawdata. Higher order beam hardening artifacts, as they result when a mixture of materials such as water and bone, or water and bone and iodine is present, require an iterative beam hardening correction where the image is segmented into different materials and those are forward projected to obtain new rawdata. Typically, the forward projection must correctly model the beam polychromaticity and account for all physical effects, including the energy dependence of the assumed materials in the patient, the detector response, and others. We propose a new algorithm that does not require any knowledge about spectra or attenuation coefficients and that does not need to be calibrated. The proposed method corrects beam hardening in single energy CT data. Methods: The only a priori knowledge entering EBHC is the segmentation of the object into different materials. Materials other than water are segmented from the original image, e.g., by using simple thresholding. Then, a (monochromatic) forward projection of these other materials is performed. The measured rawdata and the forward projected material-specific rawdata are monomially combined (e.g., multiplied or squared) and reconstructed to yield a set of correction volumes. These are then linearly combined and added to the original volume. The combination weights are determined to maximize the flatness of the new and corrected volume. EBHC is evaluated using data acquired with a modern cone-beam dual-source spiral CT scanner (Somatom Definition Flash, Siemens Healthcare, Forchheim, Germany), with a modern dual-source micro-CT scanner (TomoScope Synergy Twin, CT Imaging GmbH, Erlangen, Germany), and with a modern

  7. Reverse-Martensitic Hardening of Austenitic Stainless Steel upon Up-quenching

    NASA Astrophysics Data System (ADS)

    Sato, Kiminori; Guo, Defeng; Li, Xiaohong; Zhang, Xiangyi

    2016-08-01

    Reverse-martensitic transformation utilizing up-quenching was demonstrated for austenitic stainless steel. Up-quenching was done following the stress-induced phase modification to martensite and then enrichment of the body-centered-cubic ferrite. Transmission-electron-microscopy observation and Vickers hardness test revealed that the reverse-martensitic transformation yields quench hardening owing to an introduction of highly-concentrated dislocation. It is furthermore found that Cr precipitation on grain boundaries caused by isothermal aging is largely suppressed in the present approach.

  8. Measurements of (C-12)H4 nu-4 band halfwidths using a tunable diode laser system and a Fourier transform spectrometer

    NASA Technical Reports Server (NTRS)

    Devi, V. M.; Benner, D. C.; Rinsland, C. P.; Smith, M. A. H.

    1985-01-01

    Air-broadened and N2-broadened halfwidths at room temperature for twenty-five transitions in the nu-4 fundamental band of (C-12)H4 have been determined from IR absorption spectra recorded with a tunable diode laser spectrometer. Two tunable diode lasers operating in the 1250-1380-kayser region were used to obtain these data. Air-broadened halfwidths for twenty of these lines were also determined from additional spectra recorded at 0.01-kayser resolution with the Fourier transform spectrometer in the McMath solar telescope complex on Kitt Peak. The air-broadened halfwidths obtained from these two techniques are very consistent with agreement better than 3 percent in most cases.

  9. Transformation of the spatial coherence of pulsed laser radiation transmitted in the nonlinear regime through a multimode graded-index fibre

    SciTech Connect

    Kitsak, A I; Kitsak, M A

    2006-01-31

    A method is proposed for transformation of the spatial coherence of pulsed laser radiation upon nonlinear interaction in a multimode fibre. The specific features of the transmission of correlation properties of radiation in a graded-index fibre with regular and irregular profiles of the refractive index of the fibre core are analysed. A comparative analysis of the parameter of global degree of radiation coherence at the output of inhomogeneous waveguide and non-waveguide media is performed. It is shown that the most efficient mechanism of decorrelation of pulsed radiation in an optical fibre is fluctuations of the phase of radiation scattered by inhomogeneities of the refractive index of the fibre core induced due to nonlinear interaction with radiation with the spatially inhomogeneous intensity distribution. (control of laser radiation parameters)

  10. Final report on LDRD project 52722 : radiation hardened optoelectronic components for space-based applications.

    SciTech Connect

    Hargett, Terry W.; Serkland, Darwin Keith; Blansett, Ethan L.; Geib, Kent Martin; Sullivan, Charles Thomas; Hawkins, Samuel D.; Wrobel, Theodore Frank; Keeler, Gordon Arthur; Klem, John Frederick; Medrano, Melissa R.; Peake, Gregory Merwin; Karpen, Gary D.; Montano, Victoria A.

    2003-12-01

    This report describes the research accomplishments achieved under the LDRD Project 'Radiation Hardened Optoelectronic Components for Space-Based Applications.' The aim of this LDRD has been to investigate the radiation hardness of vertical-cavity surface-emitting lasers (VCSELs) and photodiodes by looking at both the effects of total dose and of single-event upsets on the electrical and optical characteristics of VCSELs and photodiodes. These investigations were intended to provide guidance for the eventual integration of radiation hardened VCSELs and photodiodes with rad-hard driver and receiver electronics from an external vendor for space applications. During this one-year project, we have fabricated GaAs-based VCSELs and photodiodes, investigated ionization-induced transient effects due to high-energy protons, and measured the degradation of performance from both high-energy protons and neutrons.

  11. Magnetic age hardening of cold-deformed bulk equiatomic Fe-Pd intermetallics during isothermal annealing

    NASA Astrophysics Data System (ADS)

    Deshpande, A. R.; Wiezorek, J. M. K.

    2004-03-01

    The interplay between the ordering reaction with recovery and recrystallization of the as-deformed state leads to combined reactions (CRs) during annealing of cold-deformed disordered Fe-Pd intermetallics at temperatures below the critical ordering temperature. CRs can be exploited to control the scale and morphology of the Fe-Pd alloy microstructures in order to optimize alloy properties. Here, the magnetic age hardening behavior and microstructural evolution of cold-deformed (cold rolled to 97% reduction in thickness) binary equiatomic Fe-Pd has been studied for isothermal annealing at temperatures of 400°C, 500°C, and 600°C. The evolution of the microstructure during the annealing treatments has been characterized by a combination of X-ray diffraction (XRD) and scanning electron microscopy (SEM). The magnetic age hardening behavior, the evolution of the coercivity as a function of annealing time, has been determined using a vibrating sample magnetometer (VSM). The microstructures of the transforming material have been characterized quantitatively using computer assisted image analysis methods. The CR transformed microstructures are morphologically equiaxed with average grain sizes in the sub-micron range and show coercivity up to five-fold larger than for conventionally processed equiatomic bulk Fe-Pd. During annealing the coercivity increases up to a maximum peak value and has been correlated with the increasing fraction of ordered material. The maximum coercivity obtains, as the ordering phase transformation is complete. With respect to conventionally processed material the ordering transformation in the cold-deformed material exhibits accelerated kinetics and is facilitated by a CR, which involves heterogeneous nucleation and growth processes akin to a 'massive ordering' reaction. Further annealing leads to decreasing coercivity, which has been attributed to the onset of grain growth in the population of CR-transformed grains. The characteristic magnetic

  12. A study on Fourier transform infrared spectroscopy, thermal, mechanical, NLO and laser damage properties on unidirectional Glycinium Picrate Mono Glycine crystal.

    PubMed

    Thilagavathy, S R; Rajesh, P; Ramasamy, P; Ambujam, K

    2013-11-01

    By directional solidification, single crystal of Glycinium Picrate Mono Glycine (GPMG) was successfully grown by Sankaranarayanan-Ramasamy (SR) method. An optically transparent crystal of GPMG has been grown along 〈011〉 plane by a mixed solvent of acetone and double distilled water. The evaporation rate was controlled and a single crystal of 12mm diameter and 35mm length was obtained. Single crystal X-ray diffraction, Fourier Transform Infrared Spectroscopy (FTIR), thermal, mechanical, SHG and laser damage studies were carried out. The results are discussed in detail. PMID:23892115

  13. A study on Fourier transform infrared spectroscopy, thermal, mechanical, NLO and laser damage properties on unidirectional Glycinium Picrate Mono Glycine crystal

    NASA Astrophysics Data System (ADS)

    Thilagavathy, S. R.; Rajesh, P.; Ramasamy, P.; Ambujam, K.

    2013-11-01

    By directional solidification, single crystal of Glycinium Picrate Mono Glycine (GPMG) was successfully grown by Sankaranarayanan-Ramasamy (SR) method. An optically transparent crystal of GPMG has been grown along <0 1 1> plane by a mixed solvent of acetone and double distilled water. The evaporation rate was controlled and a single crystal of 12 mm diameter and 35 mm length was obtained. Single crystal X-ray diffraction, Fourier Transform Infrared Spectroscopy (FTIR), thermal, mechanical, SHG and laser damage studies were carried out. The results are discussed in detail.

  14. Optimization of the transition path of the head hardening with using the genetic algorithms

    NASA Astrophysics Data System (ADS)

    Wróbel, Joanna; Kulawik, Adam

    2016-06-01

    An automated method of choice of the transition path of the head hardening in heat treatment process for the plane steel element is proposed in this communication. This method determines the points on the path of moving heat source using the genetic algorithms. The fitness function of the used algorithm is determined on the basis of effective stresses and yield point depending on the phase composition. The path of the hardening tool and also the area of the heat affected zone is determined on the basis of obtained points. A numerical model of thermal phenomena, phase transformations in the solid state and mechanical phenomena for the hardening process is implemented in order to verify the presented method. A finite element method (FEM) was used for solving the heat transfer equation and getting required temperature fields. The moving heat source is modeled with a Gaussian distribution and the water cooling is also included. The macroscopic model based on the analysis of the CCT and CHT diagrams of the medium-carbon steel is used to determine the phase transformations in the solid state. A finite element method is also used for solving the equilibrium equations giving us the stress field. The thermal and structural strains are taken into account in the constitutive relations.

  15. Modification of Grange-Kiefer Approach for Determination of Hardenability in Eutectoid Steel

    NASA Astrophysics Data System (ADS)

    Sushanthi, Neethi; Maity, Joydeep

    2014-09-01

    In this research work, an independent mathematical modeling approach has been adopted for determination of the hardenability of steels. In this model, at first, cooling curves were generated by solving transient heat transfer equation through discretization with pure explicit finite difference scheme coupled with MATLAB-based programming considering variable thermo-physical properties of 1080 steel. Thereafter, a new fundamental approach is proposed for obtaining CCT noses as a function of volume fraction transformed through modification of Grange-Kiefer approach. The cooling curves were solved against 50 pct transformation nose of CCT diagram in order to predict hardening behavior of 1080 steel in terms of hardenability parameters (Grossmann critical diameter, D C; and ideal critical diameter, D I) and the variation of the unhardened core diameter (D u) to diameter of steel bar (D) ratio with diameter of the steel bar (D). The experiments were also performed to ascertain actual D C value of 1080 steel for still water quenching. The D C value obtained by the developed model was found to match the experimental D C value with only 3 pct deviation. Therefore, the model developed in the present work can be used for direct determination of D I, D C and D u without resorting to any rigorous experimentation.

  16. Modification of Grange-Kiefer Approach for Determination of Hardenability in Eutectoid Steel

    NASA Astrophysics Data System (ADS)

    Sushanthi, Neethi; Maity, Joydeep

    2014-12-01

    In this research work, an independent mathematical modeling approach has been adopted for determination of the hardenability of steels. In this model, at first, cooling curves were generated by solving transient heat transfer equation through discretization with pure explicit finite difference scheme coupled with MATLAB-based programming considering variable thermo-physical properties of 1080 steel. Thereafter, a new fundamental approach is proposed for obtaining CCT noses as a function of volume fraction transformed through modification of Grange-Kiefer approach. The cooling curves were solved against 50 pct transformation nose of CCT diagram in order to predict hardening behavior of 1080 steel in terms of hardenability parameters (Grossmann critical diameter, D C; and ideal critical diameter, D I) and the variation of the unhardened core diameter ( D u) to diameter of steel bar ( D) ratio with diameter of the steel bar ( D). The experiments were also performed to ascertain actual D C value of 1080 steel for still water quenching. The D C value obtained by the developed model was found to match the experimental D C value with only 3 pct deviation. Therefore, the model developed in the present work can be used for direct determination of D I, D C and D u without resorting to any rigorous experimentation.

  17. Constitutive modelling of evolving flow anisotropy including distortional hardening

    SciTech Connect

    Pietryga, Michael P.; Vladimirov, Ivaylo N.; Reese, Stefanie

    2011-05-04

    The paper presents a new constitutive model for anisotropic metal plasticity that takes into account the expansion or contraction (isotropic hardening), translation (kinematic hardening) and change of shape (distortional hardening) of the yield surface. The experimentally observed region of high curvature ('nose') on the yield surface in the loading direction and flattened shape in the reverse loading direction are modelled here by means of the concept of directional distortional hardening. The modelling of directional distortional hardening is accomplished by means of an evolving fourth-order tensor. The applicability of the model is illustrated by fitting experimental subsequent yield surfaces at finite plastic deformation. Comparisons with test data for aluminium low and high work hardening alloys display a good agreement between the simulation results and the experimental data.

  18. Radiation hardening of diagnostics for fusion reactors

    SciTech Connect

    Baur, J.F.; Engholm, B.A.; Hacker, M.P.; Maya, I.; Miller, P.H.; Toffolo, W.E.; Wojtowicz, S.S.

    1981-12-01

    A list of the diagnostic systems presently used in magnetic confinement fusion experiments is compiled herein. The radiation-sensitive components are identified, and their locations in zones around the machine are indicated. A table of radiation sensitivities of components is included to indicate the data available from previous work in fission reactor, space probe, and defense-related programs. Extrapolation and application to hardening of fusion diagnostic systems requires additional data that are more specific to the fusion radiation environment and fusion components. A list is also given of present radiation-producing facilities where near-term screening tests of materials and components can be performed.

  19. Expecting the Unexpected: Radiation Hardened Software

    NASA Technical Reports Server (NTRS)

    Penix, John; Mehlitz, Peter C.

    2005-01-01

    Radiation induced Single Event Effects (SEEs) are a serious problem for spacecraft flight software, potentially leading to a complete loss of mission. Conventional risk mitigation has been focused on hardware, leading to slow, expensive and outdated on-board computing devices, increased power consumption and launch mass. Our approach is to look at SEEs from a software perspective, and to explicitly design flight software so that it can detect and correct the majority of SEES. Radiation hardened flight software will reduce the significant residual residual risk for critical missions and flight phases, and enable more use of inexpensive and fast COTS hardware.

  20. Strain hardening of steel EP836

    SciTech Connect

    Lyadskaya, A.A.; Lappa, R.M.; Spuskanyuk, V.Z.

    1986-03-01

    The authors investigate the effect of different combinations of cold hydraulic pressing and heat treatment on the physical and mechanical properties of steel EP836 (03N17K10V10MT), containing 0.03% C, 16-17% Ni, 10-11.5% Co, 9.5-11.5% W, 1% Ti, 1% Mo, and 0.15% A1. Deformation of the unaged steel resulted in insignificant hardening without a decrease in plasticity; this agrees with the results of investigations of other steels of this class.

  1. Salts soaking treatment for improving the textural and functional properties of trifoliate yam (Dioscorea dumetorum) hardened tubers.

    PubMed

    Medoua, G N; Mbome, I L; Egbe, T A; Mbofung, C M F

    2007-10-01

    Processing of Dioscorea dumetorum hardened tubers into flour could be a means of adding a longer-term value to this tropical plant with a high nutritional potential, but which presents a postharvest hardening problem characterized by a hard-to-cook defect. In an attempt to investigate the changes leading to salts soaking treatment of hardened tubers, the central composite rotatable design for K= 2 was used to study the combined effect of NaCl concentration (0% to 6%) and pH (4 to 10) on tubers cooked hardness, and 6 kanwa alkaline salt concentrations (1:3 (w/v); 0%, 0.2%, 0.5%, 0.8%, 1%, and 1.5%; pH 11.3 +/- 0.2) were used to study the effect of kanwa treatment on tuber cooked hardness and functional properties of resulting flours. The results showed that salts soaking treatment significantly decreased (Phardening phenomenon, as a consequence of the multiple mechanisms of D. dumetorum tuber hardening. Nevertheless, kanwa concentrations of 0.8% to 1.5% could be used to tenderize hardened tubers prior to its transformation in flour. Except oil absorption capacity, initial soaking of hardened tubers in kanwa solutions significantly influenced (P

  2. Optical diagnostics of the laser-induced phase transformations in thin germanium films on silicon, sapphire, and fused silica

    NASA Astrophysics Data System (ADS)

    Novikov, H. A.; Batalov, R. I.; Bayazitov, R. M.; Faizrakhmanov, I. A.; Ivlev, G. D.; Prokop'ev, S. L.

    2015-03-01

    The in-situ procedure is used to study the modification of thin (200-600 nm) germanium films induced by nanosecond pulses of a ruby laser. The films are produced using the ion-beam or magnetron sputtering on single-crystalline silicon (Si), sapphire (Al2O3), and fused silica (α-SiO2) substrates. The results on the dynamics of the laser-induced processes are obtained using the optical probing of the irradiated region at wavelengths of λ = 0.53 and 1.06 μm. The results of probing make it possible to determine the threshold laser energy densities that correspond to the Ge and Si melting and the generation of the Ge ablation plasma versus the amount of deposited Ge and thermophysical parameters of the substrate. The reflection oscillograms are used to obtain the dependences of the melt lifetime on the laser-pulse energy density.

  3. Technology Developments in Radiation-Hardened Electronics for Space Environments

    NASA Technical Reports Server (NTRS)

    Keys, Andrew S.; Howell, Joe T.

    2008-01-01

    The Radiation Hardened Electronics for Space Environments (RHESE) project consists of a series of tasks designed to develop and mature a broad spectrum of radiation hardened and low temperature electronics technologies. Three approaches are being taken to address radiation hardening: improved material hardness, design techniques to improve radiation tolerance, and software methods to improve radiation tolerance. Within these approaches various technology products are being addressed including Field Programmable Gate Arrays (FPGA), Field Programmable Analog Arrays (FPAA), MEMS, Serial Processors, Reconfigurable Processors, and Parallel Processors. In addition to radiation hardening, low temperature extremes are addressed with a focus on material and design approaches. System level applications for the RHESE technology products are discussed.

  4. Hardened Client Platforms for Secure Internet Banking

    NASA Astrophysics Data System (ADS)

    Ronchi, C.; Zakhidov, S.

    We review the security of e-banking platforms with particular attention to the exploitable attack vectors of three main attack categories: Man-in-the-Middle, Man-in-the-PC and Man-in-the-Browser. It will be shown that the most serious threats come from combination attacks capable of hacking any transaction without the need to control the authentication process. Using this approach, the security of any authentication system can be bypassed, including those using SecureID Tokens, OTP Tokens, Biometric Sensors and Smart Cards. We will describe and compare two recently proposed e-banking platforms, the ZTIC and the USPD, both of which are based on the use of dedicated client devices, but with diverging approaches with respect to the need of hardening the Web client application. It will be shown that the use of a Hardened Browser (or H-Browser) component is critical to force attackers to employ complex and expensive techniques and to reduce the strength and variety of social engineering attacks down to physiological fraud levels.

  5. Hardness variability in commercial and hardened technologies

    SciTech Connect

    Shaneyfelt, M.R.; Winokur, P.S.; Meisenheimer, T.L.; Sexton, F.W.; Roeske, S.B.; Knoll, M.G.

    1994-03-01

    Over the past 10 years, there have been a number of advances in methods to assess and assure the radiation hardness of microelectronics in military and space applications. At the forefront of these is the Qualified Manufacturers List (QML) methodology, in which the hardness of product is ``built-in`` through statistical process control (SPC) of technology parameters relevant to the radiation response, test structure to integrated circuit (IC) correlations, and techniques for extrapolating laboratory test results to varying radiation scenarios. At the same time, there has been renewed interest in the use of commercial technology -- with its enhanced performance, reduced cost, and higher reliability -- in military and space systems. In this paper, we initially demonstrate the application of QML techniques to assure and control the radiation response of hardened technologies. Through several examples, we demonstrate intra-die, wafer-to-wafer, and lot-to-lot variations in a hardened technology. We observe 10 to 30% variations in key technology parameters that result from variability in geometry, process, and design layout. Radiation-induced degradation is seen to mirror preirradiation characteristics. We then evaluate commercial technologies and report considerably higher variability in radiation hardness, i.e., variations by a factor of two to five. This variability is shown to arise from a lack of control of technology parameters relevant to the radiation response, which a commercial manufacturer has no interest in controlling in a normal process flow.

  6. Hardness variability in commercial and hardened technologies

    NASA Astrophysics Data System (ADS)

    Shaneyfelt, M. R.; Winokur, P. S.; Meisenheimer, T. L.; Sexton, F. W.; Roeske, S. B.; Knoll, M. G.

    1994-01-01

    Over the past 10 years, there have been a number of advances in methods to assess and assure the radiation hardness of microelectronics in military and space applications. At the forefront of these is the Qualified Manufacturers List (QML) methodology, in which the hardness of product is 'built-in' through statistical process control (SPC) of technology parameters relevant to the radiation response, test structure to integrated circuit (IC) correlations, and techniques for extrapolating laboratory test results to varying radiation scenarios. At the same time, there has been renewed interest in the use of commercial technology -- with its enhanced performance, reduced cost, and higher reliability -- in military and space systems. In this paper, we initially demonstrate the application of QML techniques to assure and control the radiation response of hardened technologies. Through several examples, we demonstrate intra-die, wafer-to-wafer, and lot-to-lot variations in a hardened technology. We observe 10 to 30% variations in key technology parameters that result from variability in geometry, process, and design layout. Radiation-induced degradation is seen to mirror preirradiation characteristics. We then evaluate commercial technologies and report considerably higher variability in radiation hardness, i.e., variations by a factor of two to five. This variability is shown to arise from a lack of control of technology parameters relevant to the radiation response, which a commercial manufacturer has no interest in controlling in a normal process flow.

  7. Analytical ultrasonics for characterization of metallurgical microstructures and transformations

    NASA Technical Reports Server (NTRS)

    Rosen, M.

    1986-01-01

    The application of contact (piezoelectric) and noncontact (laser generation and detection) ultrasonic techniques for dynamic investigation of precipitation hardening processes in aluminum alloys, as well as crystallization and phase transformation in rapidly solidified amorphous and microcrystalline alloys is discussed. From the variations of the sound velocity and attenuation the precipitation mechanism and kinetics were determined. In addition, a correlation was established between the observed changes in the velocity and attenuation and the mechanical properties of age-hardenable aluminum alloys. The behavior of the elastic moduli, determined ultrasonically, were found to be sensitive to relaxation, crystallization and phase decomposition phenomena in rapidly solidified metallic glasses. Analytical ultrasonics enables determination of the activation energies and growth parameters of the reactions. Therefrom theoretical models can be constructed to explain the changes in mechanical and physical properties upon heat treatment of glassy alloys. The composition dependence of the elastic moduli in amorphous Cu-Zr alloys was found to be related to the glass transition temperature, and consequently to the glass forming ability of these alloys. Dynamic ultrasonic analysis was found to be feasible for on-line, real-time, monitoring of metallurgical processes.

  8. Efficiency of nonstationary transformation of the spatial coherence of pulsed laser radiation in a multimode optical fibre upon self-phase modulation

    SciTech Connect

    Kitsak, M A; Kitsak, A I

    2007-08-31

    The model scheme of the nonlinear mechanism of transformation (decreasing) of the spatial coherence of a pulsed laser field in an extended multimode optical fibre upon nonstationary interaction with the fibre core is theoretically analysed. The case is considered when the spatial statistics of input radiation is caused by phase fluctuations. The analytic expression is obtained which relates the number of spatially coherent radiation modes with the spatially energy parameters on the initial radiation and fibre parameters. The efficiency of decorrelation of radiation upon excitation of the thermal and electrostriction nonlinearities in the fibre is estimated. Experimental studies are performed which revealed the basic properties of the transformation of the spatial coherence of a laser beam in a multimode fibre. The experimental results are compared with the predictions of the model of radiation transfer proposed in the paper. It is found that the spatial decorrelation of a light beam in a silica multimode fibre is mainly restricted by stimulated Raman scattering. (fiber and integrated optics)

  9. Structural characterisation of tyrosine-nitrated peptides by ultraviolet and infrared matrix-assisted laser desorption/ionisation Fourier transform ion cyclotron resonance mass spectrometry.

    PubMed

    Petre, Brínduşa-Alina; Youhnovski, Nikolay; Lukkari, Juho; Weber, Reinhold; Przybylski, Michael

    2005-01-01

    Nitration of tyrosine residues in proteins may occur in cells upon oxidative stress and inflammation processes mediated through generation of reactive nitroxyl from peroxynitrite. Tyrosine nitration from oxidative pathways may generate cytotoxic species that cause protein dysfunction and pathogenesis. A number of protein nitrations in vivo have been reported and some specific Tyrosine nitration sites have been recently identified using mass spectrometric methods. High-resolution Fourier transform ion cyclotron resonance mass spectrometry (MALDI) FT-ICR-MS) is shown here to be a highly efficient method in the determination of protein nitrations. Following the identification of nitration of the catalytic site Tyr-430 residue of bovine prostacyclin synthase, we synthesised several model peptides containing both unmodified tyrosine and 3-nitro-tyrosine residues, using solid-phase peptide synthesis (SPPS). The structures of the nitrotyrosine peptides were characterised both by ESI- and by matrix-assisted laser desorption/ionisation (MALDI)-FT-ICR-MS, using a standard ultraviolet (UV) nitrogen nitrogen laser and a 2.97 microm Nd-YAG infrared laser. Using UV-MALDI-MS, 3-nitrotyrosyl-peptides were found to undergo extensive photochemical fragmentation at the nitrophenyl group, which may hamper or prevent the unequivocal identification of Tyr-nitrations in cellular proteins. In contrast, infrared-MALDI-FT-ICR-MS did not produce fragmentation of molecular ions of Tyr-nitrated peptides. PMID:16322657

  10. Radiation-Hardened Electronics for Space Environments (RHESE)

    NASA Technical Reports Server (NTRS)

    Keys, Andrew S.; Adams, James H.; Patrick, Marshall C.; Johnson, Michael; Cressler, John D.

    2008-01-01

    This conference poster explores NASA's Radiation-Hardened Electronics for Space Environments project. This project aims to advance the state of the art in high performance, radiation-hardened electronics that enable the long-term, reliable operation of a spacecraft in extreme radiation and temperature of space and the lunar surface.

  11. Hardening treatment of friction surfaces of ball journal bearings

    NASA Astrophysics Data System (ADS)

    Gorlenko, A. O.; Davidov, S. V.

    2016-04-01

    The article presents the technology of finishing plasma hardening by the application of the multi-layer nanocoating Si-O-C-N system to harden the friction surfaces of the ball journal bearings. The authors of the paper have studied the applied wear-resistant anti-friction coating tribological characteristics, which determine the increase in wear resistance of the ball journal bearings.

  12. Radiation-Hardened Electronics for the Space Environment

    NASA Technical Reports Server (NTRS)

    Keys, Andrew S.; Watson, Michael D.

    2007-01-01

    RHESE covers a broad range of technology areas and products. - Radiation Hardened Electronics - High Performance Processing - Reconfigurable Computing - Radiation Environmental Effects Modeling - Low Temperature Radiation Hardened Electronics. RHESE has aligned with currently defined customer needs. RHESE is leveraging/advancing SOA space electronics, not duplicating. - Awareness of radiation-related activities through out government and industry allow advancement rather than duplication of capabilities.

  13. All-optical NRZ-to-PRZ format transformer with an injection-locked Fabry-Perot laser diode at unlasing condition

    NASA Astrophysics Data System (ADS)

    Chang, Yung-Cheng; Lin, Yu-Huang; Chen, J. H.; Lin, Gong-Ru

    2004-09-01

    By using an optical nonreturn-to-zero (NRZ) format data-stream to injection-lock an synchronously modulated Fabry-Perot laser diode at below threshold condition (without DC driving current), an output data-stream with pseudo-return-to-zero (PRZ) format can be generated at bit rate of up to 2.488 Gbit/s. Such an NRZ-to-PRZ format transformation is due to the injectionlocking induced gain-switching of the FPLD with the incoming NRZ data. The PRZ data-stream with a maximum on/off extinction ratio of 12.2 dB is obtained under the optical injecting power of -2 dBm and the RF driving power of 24.4 dBm. The best side-mode suppression ratio of 40 dB and the lowest timing jitter of 0.4 ps for the PRZ data-stream are observed. A power penalty of 1.2 dB is measured at a bit-error rate of 10-9 after NRZ-to-PRZ transformation. In application, the demonstration of an all-optical OR logic gate using the FPLD-based NRZ-to-PRZ transformer is also reported.

  14. Cow-eye microstructure evolution of laser pulse processed for ductile iron

    NASA Astrophysics Data System (ADS)

    Ba, Fahai; Gan, Cuihua; Yu, Gang

    2003-04-01

    Pulsed laser beam with lattice distribution was used to modify surface processing for ductile iron. The microstructures around the graphite were observed using OM, and Nanoindentation and micro-hardness of that measured from surface to inner of sample. The result shows that the graphite ball has an important effect on cow-eye microstructure evolution either in light molten area or in phase change hardened are. It is not true that assuming the material is uniform during laser rapid heating and fast cooling for the graphite ball as a dependant composition phase. The microstructures of cow-eye is made up of fine remnant austenite in light molten area, and consisted of martensite and bainite in laser modified are. The cow-eye microstructure has a transformation from martensite and bainite to pearlite with the distance increasing from surfce. At last, the microstructure evolution of cow-eye has been discussed.

  15. New analytical approach for neutron beam-hardening correction.

    PubMed

    Hachouf, N; Kharfi, F; Hachouf, M; Boucenna, A

    2016-01-01

    In neutron imaging, the beam-hardening effect has a significant effect on quantitative and qualitative image interpretation. This study aims to propose a linearization method for beam-hardening correction. The proposed method is based on a new analytical approach establishing the attenuation coefficient as a function of neutron energy. Spectrum energy shift due to beam hardening is studied on the basis of Monte Carlo N-Particle (MCNP) simulated data and the analytical data. Good agreement between MCNP and analytical values has been found. Indeed, the beam-hardening effect is well supported in the proposed method. A correction procedure is developed to correct the errors of beam-hardening effect in neutron transmission, and therefore for projection data correction. The effectiveness of this procedure is determined by its application in correcting reconstructed images. PMID:26609685

  16. Hardening and yielding in colloidal gels

    NASA Astrophysics Data System (ADS)

    Del Gado, Emanuela; Colombo, Jader; Bouzid, Mehdi

    Attractive colloidal gel networks are disordered elastic solids that can form even in extremely dilute particle suspensions. With interaction strengths comparable to the thermal energy, their stress-bearing network can locally restructure via breaking and reforming inter-particle bonds. We use molecular dynamics simulations of a model system to investigate the strain hardening and the yielding process. During shear start up protocol, the system exhibits strong localization of tensile stresses that may be released through the breaking and formation of new bonds. In this regime, the small amplitude oscillatory shear analysis shows that the storage and the loss modulus follow a power law behavior that are closely reminiscent of experimental observations. At large accumulated strains, the strain-induced reorganization of the gel may trigger flow heterogeneities and eventually lead to the yielding of the gel via a quasi brittle damage of its structure.

  17. Keystroke Dynamics-Based Credential Hardening Systems

    NASA Astrophysics Data System (ADS)

    Bartlow, Nick; Cukic, Bojan

    abstract Keystroke dynamics are becoming a well-known method for strengthening username- and password-based credential sets. The familiarity and ease of use of these traditional authentication schemes combined with the increased trustworthiness associated with biometrics makes them prime candidates for application in many web-based scenarios. Our keystroke dynamics system uses Breiman’s random forests algorithm to classify keystroke input sequences as genuine or imposter. The system is capable of operating at various points on a traditional ROC curve depending on application-specific security needs. As a username/password authentication scheme, our approach decreases the system penetration rate associated with compromised passwords up to 99.15%. Beyond presenting results demonstrating the credential hardening effect of our scheme, we look into the notion that a user’s familiarity to components of a credential set can non-trivially impact error rates.

  18. Jerky loads on surface-hardened gears

    NASA Technical Reports Server (NTRS)

    Rettig, H.; Wirth, X.

    1978-01-01

    Damage occurs again and again in practice in the form of transmissions with surface hardened gears which break after a very long operating time (explained by seldom occurring jerky loads). Gear drives are frequently exposed to jerky stresses which are greater than their fatigue limit. These stresses are considered in gear calculations, first, by shock factors when the transmission is to be designed as high endurance with regard to overloads and, second, in the form of operating ratios when the design is to be time enduring with regard to overloads. The size of the operating ratio depends not only on torque characteristics, drive and processing machine, but also on the material and heat treatment.

  19. Dilatant hardening of fluid-saturated sandstone

    NASA Astrophysics Data System (ADS)

    Makhnenko, Roman Y.; Labuz, Joseph F.

    2015-02-01

    The presence of pore fluid in rock affects both the elastic and inelastic deformation processes, yet laboratory testing is typically performed on dry material even though in situ the rock is often saturated. Techniques were developed for testing fluid-saturated porous rock under the limiting conditions of drained, undrained, and unjacketed response. Confined compression experiments, both conventional triaxial and plane strain, were performed on water-saturated Berea sandstone to investigate poroelastic and inelastic behavior. Measured drained response was used to calibrate an elasto-plastic constitutive model that predicts undrained inelastic deformation. The experimental data show good agreement with the model: dilatant hardening in undrained triaxial and plane strain compression tests under constant mean stress was predicted and observed.

  20. Precipitation hardening in 350 grade maraging steel

    SciTech Connect

    Viswanathan, U.K. . Radiometallurgy Div.); Dey, G.K. . Metallurgy Division); Asundi, M.K. )

    1993-11-01

    Evolution of microstructure in 350 grade commercial maraging steel has been examined. In the earlier stages of aging, the strengthening phases are formed by the heterogeneous precipitation, and these phases have been identified as intermetallic compounds of the Ni[sub 3] (Ti, Mo) and Fe[sub 2]Mo types. The kinetics of precipitation are studied in terms of the activation energy by carrying out isothermal hardness measurements of aged material. The mechanical properties in the peak-aged and overaged conditions were evaluated and the flow behavior examined. The overaging behavior of the steel has been studied and the formation of austenite of different morphologies identified. The crystallography of the austenite has been examined in detail. From the microstructural examination of peak-aged and deformed samples, it could be inferred that the dislocation-precipitate interaction is by precipitate shearing. Increased work hardening of the material in the overaged condition was suggestive of looping of precipitates by dislocations.

  1. Hardness depth profiling of case hardened steels using a three-dimensional photothermal technique

    NASA Astrophysics Data System (ADS)

    Qu, Hong; Wang, Chinhua; Guo, Xinxin; Mandelis, Andreas

    2010-03-01

    A method of retrieving thermophysical depth profiles of continuously inhomogeneous materials is presented both theoretically and experimentally using the three-dimensional (3-D) photothermal radiometry. A 3-D theoretical model suitable for characterizing solids with arbitrary continuously varying thermophysical property depth profiles and finite (collimated or focused) laser beam spotsize is developed. A numerical fitting algorithm to retrieve the thermophysical profile was demonstrated with three case hardened steel samples. The reconstructed thermal conductivity depth profiles were found to be well anti-correlated with microhardness profiles obtained with the conventional indenter method.

  2. Surface treatment with linearly polarized laser beam at oblique incidence

    NASA Astrophysics Data System (ADS)

    Gutu, I.; Petre, C.; Mihailescu, I. N.; Taca, M.; Alexandrescu, E.; Ivanov, I.

    2002-07-01

    An effective method for surface heat treatment with 10.6 μm linear polarized laser beam at oblique incidence is reported. A circular focused laser spot on the workpiece surface, simultaneously with 2.2-4 times increasing of the absorption are obtained in the 70-80° range of the incidence angle. The main element of the experimental setup is the astigmatic focusing head which focalize the laser beam into an elliptical spot of ellipticity ɛ>3 at normal incidence. At a proper incidence angle (obtained by the focusing head tilting) the focused laser spot on the work piece surface gets a circular form and p-state of polarization is achieved. We performed laser heat treatment (transformation hardening, surface remelting) of the uncoated surface, as well as the alloying and cladding processes by powder injection. An enhancement of the processing efficiency was obtained; in this way the investment and operation costs for surface treatment with CO 2 laser can be significantly reduced. Several technical advantages concerning the pollution of the focusing optical components, powder jet flowing and reflected radiation by the work piece surface are obtained.

  3. A temperature- and composition-dependent study of H{sub 2}SO{sub 4} aerosol optical constants using fourier transform and tunable diode laser infrared spectroscopy

    SciTech Connect

    Niedziela, R.F.; Norman, M.L.; DeForest, C.L.; Miller, R.E.; Worsnop, D.R.

    1999-10-07

    Frequency-dependent optical constants have been determined from the Fourier transform infrared spectra of laboratory-generated liquid sulfuric acid/water aerosols over a range of temperatures and compositions that are relevant to the upper troposphere and lower stratosphere of Earth. The compositions of the particles were determined in situ using a tunable diode laser to monitor equilibrium water vapor pressures. The infrared complex refractive indices of sulfuric acid are shown to be strongly dependent on temperature and composition, because of changes in the equilibrium between sulfate and bisulfate ions. Results from this study also have implications in understanding the temperature dependence of intermolecular interactions within ionic solutions. The database presented here is the most extensive yet available for the liquid solutions of sulfuric acid.

  4. Ultrafast generation of ferromagnetic order via a laser-induced phase transformation in FeRh thin films.

    PubMed

    Ju, Ganping; Hohlfeld, Julius; Bergman, Bastiaan; van de Veerdonk, René J M; Mryasov, Oleg N; Kim, Jai-Young; Wu, Xiaowei; Weller, Dieter; Koopmans, Bert

    2004-11-01

    It is demonstrated that ultrafast generation of ferromagnetic order can be achieved by driving a material from an antiferromagnetic to a ferromagnetic state using femtosecond optical pulses. Experimental proof is provided for chemically ordered FeRh thin films. A subpicosecond onset of induced ferromagnetism is followed by a slower increase over a period of about 30 ps when FeRh is excited above a threshold fluence. Both experiment and theory provide evidence that the underlying phase transformation is accompanied, but not driven, by a lattice expansion. The mechanism for the observed ultrafast magnetic transformation is identified to be the strong ferromagnetic exchange mediated via Rh moments induced by Fe spin fluctuations. PMID:15600878

  5. Properties of modified anhydride hardener and its cured resin

    NASA Astrophysics Data System (ADS)

    Qiang, Chen; Bingjun, Gao; Jinglin, Chen; Tongzhao, Xu

    2000-01-01

    Methyl-nadic-tetrahydric-methylanhydride (MNA), nadic-tetrahydric-methylanhydride (NA), anhydride hardener was modified by solid diol molecule to improve the impregnation resin fracture toughness in cryogenic temperature. The lap-shear strength, transverse tension as well as the thermal shock test showed that the resin cured by the modified anhydride hardener had higher bond strength and more toughness at 77 K. After the experiment of vacuum pressure impregnation (VPI) processing, it was found that this resin had a longer usable life, better impregnating properties, but higher initial viscosity than the resin hybrid HY925 as hardener.

  6. Strain hardening of metal parts with use of impulse wave

    NASA Astrophysics Data System (ADS)

    Kirichek, A. V.; Soloviev, D. L.

    2016-04-01

    This work describes a strain hardening method with the use of impulse waves. This method increases energy transfer to the strained material extending its technological capabilities with development of a deep strengthened layer and allowing formation of a heterogeneous hardened structure using plastic deformation. This structure has specified distribution of the hard and soft (visco-plastic) areas. Due to development of the heterogeneous structure in the surface layer created by strain hardening with impulse wave, durability of parts that suffer contact fatigue loading is significantly increased.

  7. Exploring Biosignatures Associated with Thenardite by Geomatrix-Assisted Laser Desorption/Ionization Fourier Transform Ion Cyclotron Resonance Mass Spectrometry (GALDI-FTICR-MS)

    SciTech Connect

    C. Doc Richardson; Nancy W. Hinman; Timothy R. McJunkin; J. Michelle Kotler; Jill R. Scott

    2008-10-01

    Geomatrix-assisted laser desorption/ionization (GALDI) in conjunction with a Fourier transform ion cyclotron resonance mass spectrometer (FTICR-MS) has been employed to determine how effectively bio/organic molecules associated with the mineral thenardite (Na2SO4) can be detected. GALDI is based on the ability of the mineral host to assist desorption and ionization of bio/organic molecules without additional sample preparation. When glycine was mixed with thenardite, glycine was deprotonated to produce C2H4NO-2 at m/z 74.025. The combination of stearic acid with thenardite produced a complex cluster ion at m/z 390.258 in the negative mode, which was assigned a composition ofC18H39O7Na-. Anatural sample of thenardite from Searles Lake in California also produced a peak at m/z 390.260. The bio/organic signatures in both the laboratory-based and natural samples were heterogeneously dispersed as revealed by chemical imaging. The detection limits for the stearic acid and thenardite combination were estimated to be 3 parts per trillion or~7 zeptomoles (10-21) per laser spot. Attempts to improve the signal-to-noise ratio by co-adding FTICR-MS data predetermined to contain the biosignatures of interest revealed problems due to a lack of phase coherence between data sets.

  8. Experimental investigations of the internal energy of molecules evaporated via laser-induced acoustic desorption into a Fourier transform ion cyclotron resonance mass spectrometer.

    PubMed

    Shea, Ryan C; Petzold, Christopher J; Liu, Ji-Ang; Kenttämaa, Hilkka I

    2007-03-01

    The internal energy of neutral gas-phase organic and biomolecules, evaporated by means of laser-induced acoustic desorption (LIAD) into a Fourier transform ion cyclotron resonance mass spectrometer, was investigated through several experimental approaches. The desorbed molecules were demonstrated not to undergo degradation during the desorption process by collecting LIAD-evaporated molecules and subjecting them to analysis by electrospray ionization/quadrupole ion trap mass spectrometry. Previously established gas-phase basicity values were remeasured for LIAD-evaporated organic molecules and biomolecules with the use of the bracketing method. No endothermic reactions were observed. The remeasured basicity values are in close agreement with the values reported in the literature. The amount of internal energy deposited during LIAD is concluded to be less than a few kilocalories per mole. Chemical ionization with a series of proton-transfer reagents was employed to obtain a breakdown curve for a protonated dipeptide, Val-Pro, evaporated by LIAD. Comparison of this breakdown curve with a previously published analogous curve obtained by using substrate-assisted laser desorption (SALD) to evaporate the peptide suggests that the molecules evaporated via LIAD have a similar internal energy as those evaporated via SALD. PMID:17263513

  9. Study of cluster anions generated by laser ablation of titanium oxides: a high resolution approach based on Fourier transform ion cyclotron resonance mass spectrometry.

    PubMed

    Barthen, Nicolas; Millon, Eric; Aubriet, Frédéric

    2011-03-01

    Laser ablation of titanium oxides at 355 nm and ion-molecule reactions between [(TiO(2))(x)](-•) cluster anions and H(2)O or O(2) were investigated by Fourier transform ion cyclotron resonance mass spectrometry (FTICR MS) with an external ion source. The detected anions correspond to [(TiO(2))(x)(H(2)O)(y)OH](-) and [(TiO(2))(x)(H(2)O)(y)O(2)](-•) oxy-hydroxide species with x=1 to 25 and y=1, 2, or 3 and were formed by a two step process: (1) laser ablation, which leads to the formation of [(TiO(2))(x)](-•) cluster anions as was previously reported, and (2) ion-molecule reactions during ion storage. Reactions of some [(TiO(2))(x)](-•) cluster anions with water and dioxygen conducted in the FTICR cell confirm this assessment. Tandem mass spectrometry experiments were also performed in sustained off-resonance irradiation collision-induced dissociation (SORI-CID) mode. Three fragmentation pathways were observed: (1) elimination of water molecules, (2) O(2) loss for radical anions, and (3) fission of the cluster. Density functional theory (DFT) calculations were performed to explain the experimental data. PMID:21472569

  10. Producing gapped-ferrite transformer cores

    NASA Technical Reports Server (NTRS)

    Mclyman, W. T.

    1980-01-01

    Improved manufacturing techniques make reproducible gaps and minimize cracking. Molded, unfired transformer cores are cut with thin saw and then fired. Hardened semicircular core sections are bonded together, placed in aluminum core box, and fluidized-coated. After winding is run over box, core is potted. Economical method significantly reduces number of rejects.

  11. Pt metallization of laser transformed medical grade silicone rubber: Last step toward a miniaturized nerve electrode fabrication process

    NASA Astrophysics Data System (ADS)

    Dupas-Bruzek, C.; Dréan, P.; Derozier, D.

    2009-10-01

    Chronic nerve recording and stimulation became possible through the use of implanted electrodes cuffs. In particular, self-sizing spiral electrode cuffs limit mechanical damage to the tissue: these have been shown to be suitable for long term implantation in animal and in man. However, up to now, such electrode cuffs were handmade and were hardly reproducible. They possessed a small number of electrodes (dot contacts), each being linked to its own wire. In order to improve the selectivity of nerve recording and/or stimulation (functional electrical stimulation), the numbers of electrodes and tracks have to be increased within the same electrode cuff surface. To fulfill this requirement, we have developed a fabrication process that uses an UV laser to induce surface modification, which activates the silicone rubber and is used with a mask to give high definition tracks and electrodes. After this primary step, silicone rubber is immersed in a Pt autocatalytic bath leading to a selective Pt metallization of the laser activated tracks and electrodes. We report our process as well as the results on the Pt metallization, including its morphology, how the DC resistance of Pt tracks depends on the laser used and the irradiation conditions, and also the electrical resistance of Pt tracks submitted to Scotch tape tests or to imposed strains. We show that (i) the type of laser and the irradiation conditions have a strong influence on the nucleation and growth rate of platinum and thus on the DC resistance of the tracks, (ii) the tracks of width 400 μm and thickness 10 μm have a sheet resistivity of 0.2 Ω/sq, (iii) DC resistance does not change much during a 6 month soak in saline, (iv) strains above 2% breaks the track continuity, and (v) when strains below 53% are relaxed, the DC resistance returns to a low value. This recovery from large tensile strains means that nerve cuffs with such metallization could be handled by the surgeon without great care before and during

  12. Crystallographic measurement of the β to α phase transformation and δ-hydride precipitation in a laser-welded Zircaloy-2 tube by electron backscattering diffraction

    NASA Astrophysics Data System (ADS)

    Une, K.; Ishimoto, S.

    2009-06-01

    Crystallographic measurement of the β to α phase transformation and δ-hydride precipitation in a laser-welded Zircaloy-2 ferrule tube were carried out using an electron backscattering diffraction pattern (EBSP). A basket-weave structure with sub-micron lath width caused by quenching from the β to α phase was observed in the heat-affected and fusion zones, and mainly showed a grain boundary misorientation angle of 60° with an <1 1 2¯ 0> rotation axis. This result is consistent with the Burgers orientation relationship of {1 1 0} β//(0 0 0 1) α and <1 1 1> β//<1 1 2¯ 0> α for the β to α phase transformation. The texture of the quenched α' phase was strongly inherited from the original α phase, having a radial (0 0 0 1) basal pole and axial {1 1 2¯ 0} textures, even in the fusion zone. The primary hydride habit plane in the welded Zircaloy-2 was (0 0 0 1) α//{1 1 1} δ, matching previously obtained results for recrystallized cladding tubes. In addition to the primary habit plane, secondary habit planes were observed for the other low-index planes {1 0 1¯ 0} and {1 0 1¯ 1} in the fusion zone. The heterogeneous accumulation of hydrides in the transition zone between heat-affected and unaffected zones was mainly due to the residual stress distribution in the narrow region.

  13. Beam Hardening Corrections in Quantitative Computed Tomography

    SciTech Connect

    Vedula, Venumadhav; Venugopal, Manoharan; Raghu, C.; Pandey, Pramod

    2007-03-21

    Volumetric computed tomography (VCT) is the emerging 3D NDE inspection technique that gives highest throughput and better image quality. Industrial components in general demands higher x-ray energy for inspection for which polychromatic x-ray sources are used in common. Polychromatic nature of the x-rays gives rise to non-linear effects in the VCT projection data measurements called to be the beam hardening (BH) effects. BH produces prominent artifacts in the reconstructed images thereby deteriorating the image quality. Quantitative analysis such as density quantification, dimensional analysis etc., becomes difficult with the presence of these artifacts. This paper describes the BH correction using preprocessing technique for the homogeneous materials. Selection of effective energy at which the monoenergetic linear attenuation coefficient of a particular material equals to that of the polyenergetic beam is critical for BH correction. Various methods to determine the effective energy and their consequence in the quantitative measurements have been investigated in the present study. In this paper, BH corrections for heterogeneous materials have also been explored.

  14. Design concepts for hardened communications structures

    NASA Astrophysics Data System (ADS)

    Flathau, William J.; Smith, William G.

    1990-03-01

    An important component of any hardened command and control structure is the antenna system that provides communication with the outside world. Two types of antennae were considered; i.e., the whip type and the directional. The whip type is for short range communication and the directional is for use primarily with satellites. In the super high frequency range, the use of directional antennae having parabolic dishes greater than 8 feet in diameter are common. In the very extra high frequency range, dishes that are 2 to 3 feet in diameter are used. The whip type antenna should extend up to, say, 60 feet in the air. Based on this background, a family of structures was designed that can protect whip and directional antennae from the blast and shock effects from a 1-MT device for ground surface overpressure ranging from 15,000 to 500 psi. As the antennae, transmitters, receivers, power supplies, and lifting mechanisms will be located within such structures, appropriate shock spectra plots were developed to determine if the fragility level of pertinent equipment will be exceeded and for use in designing shock isolation systems. Button up periods of 1 and 4 weeks were considered.

  15. Weldable, age hardenable, austenitic stainless steel

    DOEpatents

    Brooks, J.A.; Krenzer, R.W.

    1975-07-22

    An age hardenable, austenitic stainless steel having superior weldability properties as well as resistance to degradation of properties in a hydrogen atmosphere is described. It has a composition of from about 24.0 to about 34.0 weight percent (w/o) nickel, from about 13.5 to about 16.0 w/o chromium, from about 1.9 to about 2.3 w/o titanium, from about 1.0 to about 1.5 w/ o molybdenum, from about 0.01 to about 0.05 w/o carbon, from about 0 to about 0.25 w/o manganese, from about 0 to about 0.01 w/o phosphorous and preferably about 0.005 w/o maximum, from about 0 to about 0.010 w/o sulfur and preferably about 0.005 w/o maximum, from about 0 to about 0.25 w/o silicon, from about 0.1 to about 0.35 w/o aluminum, from about 0.10 to about 0.50 w/o vanadium, from about 0 to about 0.0015 w/o boron, and the balance essentially iron. (auth)

  16. Cyber situational awareness and differential hardening

    NASA Astrophysics Data System (ADS)

    Dwivedi, Anurag; Tebben, Dan

    2012-06-01

    The advent of cyber threats has created a need for a new network planning, design, architecture, operations, control, situational awareness, management, and maintenance paradigms. Primary considerations include the ability to assess cyber attack resiliency of the network, and rapidly detect, isolate, and operate during deliberate simultaneous attacks against the network nodes and links. Legacy network planning relied on automatic protection of a network in the event of a single fault or a very few simultaneous faults in mesh networks, but in the future it must be augmented to include improved network resiliency and vulnerability awareness to cyber attacks. Ability to design a resilient network requires the development of methods to define, and quantify the network resiliency to attacks, and to be able to develop new optimization strategies for maintaining operations in the midst of these newly emerging cyber threats. Ways to quantify resiliency, and its use in visualizing cyber vulnerability awareness and in identifying node or link criticality, are presented in the current work, as well as a methodology of differential network hardening based on the criticality profile of cyber network components.

  17. Characterization of Nanoscale Transformations in Polyelectrolyte Multilayers Fabricated from Plasmid DNA Using Laser Scanning Confocal Microscopy in Combination with Atomic Force Microscopy

    PubMed Central

    Fredin, Nathaniel J.; Flessner, Ryan M.; Jewell, Christopher M.; Bechler, Shane L.; Buck, Maren E.; Lynn, David M.

    2010-01-01

    Laser scanning confocal microscopy (LSCM) and atomic force microscopy (AFM) were used to characterize changes in nanoscale structure that occur when ultrathin polyelectrolyte multilayers (PEMs) are incubated in aqueous media. The PEMs investigated here were fabricated by the deposition of alternating layers of plasmid DNA and a hydrolytically degradable polyamine onto a precursor film composed of alternating layers of linear poly(ethylene imine) (LPEI) and sodium poly(styrene sulfonate) (SPS). Past studies of these materials in the context of gene delivery revealed transformations from a morphology that is smooth and uniform to one characterized by the formation of nanometer-scale particulate structures. We demonstrate that in-plane registration of LSCM and AFM images acquired from the same locations of films fabricated using fluorescently labeled polyelectrolytes allows the spatial distribution of individual polyelectrolyte species to be determined relative to the locations of topographic features that form during this transformation. Our results suggest that this physical transformation leads to a morphology consisting of a relatively less disturbed portion of film composed of polyamine and DNA juxtaposed over an array of particulate structures composed predominantly of LPEI and SPS. Characterization by scanning electron microscopy (SEM) and energy-dispersive X-ray (EDX) microanalysis provides additional support for this interpretation. The combination of these different microscopy techniques provides insight into the structures and dynamics of these multicomponent thin films that cannot be achieved using any one method alone, and that could prove useful for the further development of these assemblies as platforms for the surface-mediated delivery of DNA. PMID:20155860

  18. Microscopic Origin of Strain Hardening in Methane Hydrate

    PubMed Central

    Jia, Jihui; Liang, Yunfeng; Tsuji, Takeshi; Murata, Sumihiko; Matsuoka, Toshifumi

    2016-01-01

    It has been reported for a long time that methane hydrate presents strain hardening, whereas the strength of normal ice weakens with increasing strain after an ultimate strength. However, the microscopic origin of these differences is not known. Here, we investigated the mechanical characteristics of methane hydrate and normal ice by compressive deformation test using molecular dynamics simulations. It is shown that methane hydrate exhibits strain hardening only if the hydrate is confined to a certain finite cross-sectional area that is normal to the compression direction. For normal ice, it does not present strain hardening under the same conditions. We show that hydrate guest methane molecules exhibit no long-distance diffusion when confined to a finite-size area. They appear to serve as non-deformable units that prevent hydrate structure failure, and thus are responsible for the strain-hardening phenomenon. PMID:27009239

  19. Possible correlation between work-hardening and fatigue-failure

    NASA Technical Reports Server (NTRS)

    Kettunen, P. O.; Kocks, U. F.

    1969-01-01

    Conceptual theory proposes that cyclic hardening due to non-uniform strain and stress amplitudes during testing, especially during the initial application of stress to a specimen, may correlate positively with the ultimate strength of the specimen under test.

  20. Stress corrosion cracking evaluation of precipitation-hardening stainless steel

    NASA Technical Reports Server (NTRS)

    Humphries, T. S.; Nelson, E. E.

    1970-01-01

    Accelerated test program results show which precipitation hardening stainless steels are resistant to stress corrosion cracking. In certain cases stress corrosion susceptibility was found to be associated with the process procedure.

  1. Microscopic Origin of Strain Hardening in Methane Hydrate.

    PubMed

    Jia, Jihui; Liang, Yunfeng; Tsuji, Takeshi; Murata, Sumihiko; Matsuoka, Toshifumi

    2016-01-01

    It has been reported for a long time that methane hydrate presents strain hardening, whereas the strength of normal ice weakens with increasing strain after an ultimate strength. However, the microscopic origin of these differences is not known. Here, we investigated the mechanical characteristics of methane hydrate and normal ice by compressive deformation test using molecular dynamics simulations. It is shown that methane hydrate exhibits strain hardening only if the hydrate is confined to a certain finite cross-sectional area that is normal to the compression direction. For normal ice, it does not present strain hardening under the same conditions. We show that hydrate guest methane molecules exhibit no long-distance diffusion when confined to a finite-size area. They appear to serve as non-deformable units that prevent hydrate structure failure, and thus are responsible for the strain-hardening phenomenon. PMID:27009239

  2. Ultimate bending capacity of strain hardening steel pipes

    NASA Astrophysics Data System (ADS)

    Chen, Yan-fei; Zhang, Juan; Zhang, Hong; Li, Xin; Zhou, Jing; Cao, Jing

    2016-04-01

    Based on Hencky's total strain theory of plasticity, ultimate bending capacity of steel pipes can be determined analytically assuming an elastic-linear strain hardening material, the simplified analytical solution is proposed as well. Good agreement is observed when ultimate bending capacities obtained from analytical solutions are compared with experimental results from full-size tests of steel pipes. Parametric study conducted as part of this paper indicates that the strain hardening effect has significant influence on the ultimate bending capacity of steel pipes. It is shown that pipe considering strain hardening yields higher bending capacity than that of pipe assumed as elastic-perfectly plastic material. Thus, the ignorance of strain hardening effect, as commonly assumed in current codes, may underestimate the ultimate bending capacity of steel pipes. The solutions proposed in this paper are applicable in the design of offshore/onshore steel pipes, supports of offshore platforms and other tubular structural steel members.

  3. Time history of laser pulse polarization transformation as a tool of the isotropic-nematic phase transition in liquid crystals

    NASA Astrophysics Data System (ADS)

    Makarov, Vladimir A.; Il'inova, Tamara M.; Marchenko, Tatiana B.; Shkurinov, Aleksandr P.; Zolot'ko, Alexander S.

    2003-06-01

    We theoretically investigate in the aberrationless approximation the self-action of the elliptically polarized Gaussian pulse during its propagation in a thin dish with a nematic liquid crystal in the isotropic phase. Quadrature formulas are obtained to describe the time history of the intensity, the elliptisity degree and the rotation angle of the polarization ellipse of the output radiation at the different points of the beam cross-section. They are expressed in terms of the parameters describing two, essential near the temperature of the isotropic-nematic phase transition, mechanisms of the spatial nonlocality of the nonlinear medium optical response, and in terms of the other parameters, which describe the nematic liquid crystal and the elliptically polarized incident pulse. The former mechanism is specified by the medium heating due to light absorption; the latter is determined by the fluctuations of the nematic liquid crystal order parameter tensor near the temperature of the isotropic-nematic phase transition. It is shown that for some values of temperature and of the nematic liquid crystal parameters the elliptical polarization of the incident pulse, which is constant at the entry of the thin dish, transforms into the linear or another different elliptical one at the exit and keeps this new state up to the pulse tail. The dependence of the ellipticity degree on time becomes significantly nonmonotonic and changes its sign in some cases. The nonlocality of the nonlinear medium optical response weakens these transformations.

  4. Strain hardening of fcc metal surfaces induced by microploughing

    SciTech Connect

    Day, R.D.; Dickerson, R.M.; Russell, P.E.

    1998-12-01

    Microploughing experiments were used as a method for better understanding the ploughing mechanism in gold and iridium single crystals. The plough depths ranged from 20 nm in iridium to 1,600 nm in gold. Yield stress profiles and TEM analyses indicate that both materials strain harden even when very small volumes of material are involved. Strain hardening theory, as applied to bulk material, is useful in analyzing the results.

  5. Evaluation of combined matrix-assisted laser desorption/ionization time-of-flight and matrix-assisted laser desorption/ionization Fourier transform ion cyclotron resonance mass spectrometry experiments for peptide mass fingerprinting analysis.

    PubMed

    da Silva, David; Wasselin, Thierry; Carré, Vincent; Chaimbault, Patrick; Bezdetnaya, Lina; Maunit, Benoît; Muller, Jean-François

    2011-07-15

    Peptide Mass Fingerprinting (PMF) is still of significant interest in proteomics because it allows a large number of complex samples to be rapidly screened and characterized. The main part of post-translational modifications is generally preserved. In some specific cases, PMF suffers from ambiguous or unsuccessful identification. In order to improve its reliability, a combined approach using matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOFMS) and matrix-assisted laser desorption/ionization Fourier transform ion cyclotron resonance mass spectrometry (MALDI-FTICRMS) was evaluated. The study was carried out on bovine serum albumin (BSA) digest. The influence of several important parameters (the matrix, the sample preparation method, the amount of the analyte) on the MOWSE score and the protein sequence coverage were evaluated to allow the identification of specific effects. A careful investigation of the sequence coverage obtained by each kind of experiment ensured the detection of specific peptides for each experimental condition. Results highlighted that DHB-FTICRMS and DHB- or CHCA-TOFMS are the most suited combinations of experimental conditions to achieve PMF analysis. The association (convolution) of the data obtained by each of these techniques ensured a significant increase in the MOWSE score and the protein sequence coverage. PMID:21638364

  6. Zinc coated sheet steel for press hardening

    NASA Astrophysics Data System (ADS)

    Ghanbari, Zahra N.

    Galvanized steels are of interest to enhance corrosion resistance of press-hardened steels, but concerns related to liquid metal embrittlement have been raised. The objective of this study was to assess the soak time and temperature conditions relevant to the hot-stamping process during which Zn penetration did or did not occur in galvanized 22MnB5 press-hardening steel. A GleebleRTM 3500 was used to heat treat samples using hold times and temperatures similar to those used in industrial hot-stamping. Deformation at both elevated temperature and room temperature were conducted to assess the coating and substrate behavior related to forming (at high temperature) and service (at room temperature). The extent of alloying between the coating and substrate was assessed on undeformed samples heat treated under similar conditions to the deformed samples. The coating transitioned from an α + Gamma1 composition to an α (bcc Fe-Zn) phase with increased soak time. This transition likely corresponded to a decrease in availability of Zn-rich liquid in the coating during elevated temperature deformation. Penetration of Zn into the substrate sheet in the undeformed condition was not observed for any of the processing conditions examined. The number and depth of cracks in the coating and substrate steel was also measured in the hot-ductility samples. The number of cracks appeared to increase, while the depth of cracks appeared to decrease, with increasing soak time and increasing soak temperature. The crack depth appeared to be minimized in the sample soaked at the highest soak temperature (900 °C) for intermediate and extended soak times (300 s or 600 s). Zn penetration into the substrate steel was observed in the hot-ductility samples soaked at each hold temperature for the shortest soak time (10 s) before being deformed at elevated temperature. Reduction of area and elongation measurements showed that the coated sample soaked at the highest temperature and longest soak time

  7. Extracting material response from simple mechanical tests on hardening-softening-hardening viscoplastic solids

    NASA Astrophysics Data System (ADS)

    Mohan, Nisha

    Compliant foams are usually characterized by a wide range of desirable mechanical properties. These properties include viscoelasticity at different temperatures, energy absorption, recoverability under cyclic loading, impact resistance, and thermal, electrical, acoustic and radiation-resistance. Some foams contain nano-sized features and are used in small-scale devices. This implies that the characteristic dimensions of foams span multiple length scales, rendering modeling their mechanical properties difficult. Continuum mechanics-based models capture some salient experimental features like the linear elastic regime, followed by non-linear plateau stress regime. However, they lack mesostructural physical details. This makes them incapable of accurately predicting local peaks in stress and strain distributions, which significantly affect the deformation paths. Atomistic methods are capable of capturing the physical origins of deformation at smaller scales, but suffer from impractical computational intensity. Capturing deformation at the so-called meso-scale, which is capable of describing the phenomenon at a continuum level, but with some physical insights, requires developing new theoretical approaches. A fundamental question that motivates the modeling of foams is `how to extract the intrinsic material response from simple mechanical test data, such as stress vs. strain response?' A 3D model was developed to simulate the mechanical response of foam-type materials. The novelty of this model includes unique features such as the hardening-softening-hardening material response, strain rate-dependence, and plastically compressible solids with plastic non-normality. Suggestive links from atomistic simulations of foams were borrowed to formulate a physically informed hardening material input function. Motivated by a model that qualitatively captured the response of foam-type vertically aligned carbon nanotube (VACNT) pillars under uniaxial compression [2011,"Analysis of

  8. Processing, Microstructures and Properties of a Dual Phase Precipitation-Hardening PM Stainless Steel

    NASA Astrophysics Data System (ADS)

    Schade, Christopher

    To improve the mechanical properties of PM stainless steels in comparison with their wrought counterparts, a PM stainless steel alloy was developed which combines a dual-phase microstructure with precipitation-hardening. The use of a mixed microstructure of martensite and ferrite results in an alloy with a combination of the optimum properties of each phase, namely strength and ductility. The use of precipitation hardening via the addition of copper results in additional strength and hardness. A range of compositions was studied in combination with various sintering conditions to determine the optimal thermal processing to achieve the desired microstructure. The microstructure could be varied from predominately ferrite to one containing a high percentage of martensite by additions of copper and a variation of the sintering temperature before rapid cooling. Mechanical properties (transverse rupture strength (TRS), yield strength, tensile strength, ductility and impact toughness) were measured as a function of the v/o ferrite in the microstructure. A dual phase alloy with the optimal combination of properties served as the base for introducing precipitation hardening. Copper was added to the base alloy at various levels and its effect on the microstructure and mechanical properties was quantified. Processing at various sintering temperatures led to a range of microstructures; dilatometry was used utilized to monitor and understand the transformations and the formation of the two phases. The aging process was studied as a function of temperature and time by measuring TRS, yield strength, tensile strength, ductility, impact toughness and apparent hardness. It was determined that optimum aging was achieved at 538°C for 1h. Aging at slightly lower temperatures led to the formation of carbides, which contributed to reduced hardness and tensile strength. As expected, at the peak aging temperature, an increase in yield strength and ultimate tensile strength as well as

  9. High-Performance, Radiation-Hardened Electronics for Space Environments

    NASA Technical Reports Server (NTRS)

    Keys, Andrew S.; Watson, Michael D.; Frazier, Donald O.; Adams, James H.; Johnson, Michael A.; Kolawa, Elizabeth A.

    2007-01-01

    The Radiation Hardened Electronics for Space Environments (RHESE) project endeavors to advance the current state-of-the-art in high-performance, radiation-hardened electronics and processors, ensuring successful performance of space systems required to operate within extreme radiation and temperature environments. Because RHESE is a project within the Exploration Technology Development Program (ETDP), RHESE's primary customers will be the human and robotic missions being developed by NASA's Exploration Systems Mission Directorate (ESMD) in partial fulfillment of the Vision for Space Exploration. Benefits are also anticipated for NASA's science missions to planetary and deep-space destinations. As a technology development effort, RHESE provides a broad-scoped, full spectrum of approaches to environmentally harden space electronics, including new materials, advanced design processes, reconfigurable hardware techniques, and software modeling of the radiation environment. The RHESE sub-project tasks are: SelfReconfigurable Electronics for Extreme Environments, Radiation Effects Predictive Modeling, Radiation Hardened Memory, Single Event Effects (SEE) Immune Reconfigurable Field Programmable Gate Array (FPGA) (SIRF), Radiation Hardening by Software, Radiation Hardened High Performance Processors (HPP), Reconfigurable Computing, Low Temperature Tolerant MEMS by Design, and Silicon-Germanium (SiGe) Integrated Electronics for Extreme Environments. These nine sub-project tasks are managed by technical leads as located across five different NASA field centers, including Ames Research Center, Goddard Space Flight Center, the Jet Propulsion Laboratory, Langley Research Center, and Marshall Space Flight Center. The overall RHESE integrated project management responsibility resides with NASA's Marshall Space Flight Center (MSFC). Initial technology development emphasis within RHESE focuses on the hardening of Field Programmable Gate Arrays (FPGA)s and Field Programmable Analog

  10. Assessment of the microstructure and torsional fatigue performance of an induction hardened vanadium microalloyed medium-carbon steel

    NASA Astrophysics Data System (ADS)

    Rothleutner, Lee M.

    -martensitic transformation products in the induction-hardened case. In the total case region, vanadium reduced the total case depth by inhibiting austenite formation at low austenitizing temperatures; however, the non-martensitic constituents in the case microstructure and the reduced total case depth of the vanadium microalloyed steel did not translate directly to a degradation of torsional fatigue properties. In general, vanadium microalloying was not found to affect torsional fatigue performance significantly with one exception. In the 25 pct effective case depth condition, the 10V45 steel had a ~75 pct increase in fatigue life at all shear stress amplitudes when compared to the 1045 steel. The improved fatigue performance is likely a result of the significantly higher case hardness this condition exhibited compared to all other conditions. The direct influence of vanadium on the improved fatigue life of the 25 pct effective case depth condition is confounded with the slightly higher carbon content of the 10V45 steel. In addition, the 10V45 conditions showed a consistently higher case hardness than the in 1045 conditions. The increased hardness of the 10V45 steel did not increase the compressive residual stresses at the surface. Induction hardening parameters were more closely related to changes in residual stress than vanadium microalloying additions. Torsional fatigue data from the current study as well as from literature were used to develop an empirical multiple linear regression model that accounts for case depth as well as carbon content when predicting torsional fatigue life of induction hardened medium-carbon steels.

  11. Detection of Biosignatures using Geomatrix-Assisted Laser Desorption/Ionization Fourier Transform Ion Cyclotron Resonance Mass Spectrometry: Implications for the Search for Life in the Solar System

    NASA Astrophysics Data System (ADS)

    Richardson, C. D.; Kotler, J. M.; Hinman, N. W.; Scott, J. R.

    2008-12-01

    Detection of bio/organic signatures, defined as an organic structure produced by living organisms or derived from other biogenic organic compounds, is essential to investigating the origin and distribution of extant or extinct life in the solar system. In conjunction with mineralogical, inorganic, and isotopic data, the detection and identification of bio/organic signatures can assist in linking biochemical and geochemical processes. Geomatrix-assisted laser desorption/ionization (GALDI) in conjunction with a Fourier transform ion cyclotron resonance mass spectrometry (FTICR-MS) is a proven method of obtaining bio/organic signatures from a range of geological materials. Sulfate salts were studied because they are found on Mars and Jovian satellites. The goal here was to determine (1) which combinations of bio/organic compounds and sulfate salts produced distinctive spectral signatures, and (2) the detection limit of the method. In these experiments, thenardite (Na2SO4) was mixed with stearic acid to determine the detection limit of GALDI-FTICR-MS, previously estimated to be 3 ppt, which corresponds to approximately 7 zeptomoles (10-21) per laser shot. All spectra were collected with little to no sample preparation and were acquired using a single laser shot. Unlike conventional analytical practices, the signal-to-noise ratio increased as the concentration of bio/organic compounds decreased relative to the mineral host. In combination with thenardite, aromatic amino acids were observed to undergo simple cation attachment ([M+Na]+) due to the π-bonded aromatic ring. Subsequent cation substitution of the carboxyl group led to formation of peaks representing double cation attachment ([M-H+Na]Na+). Spectra from naturally occurring thenardite and jarosite (XFe3(OH)6(SO4)2) revealed the presence of high mass cluster ions; analysis of their isotopic distribution suggested the presence of bio/organic compounds. High mass cluster ions, both organic and inorganic, readily

  12. Anisotropic hardening model based on non-associated flow rule and combined nonlinear kinematic hardening for sheet materials

    NASA Astrophysics Data System (ADS)

    Taherizadeh, Aboozar; Green, Daniel E.; Yoon, Jeong W.

    2013-12-01

    A material model for more effective analysis of plastic deformation of sheet materials is presented in this paper. The model is capable of considering the following aspects of plastic deformation behavior of sheet materials: the anisotropy in yielding stresses in different directions by using a quadratic yield function (based on Hill's 1948 model and stress ratios), the anisotropy in work hardening by introducing non-constant flow stress hardening in different directions, the anisotropy in plastic strains in different directions by using a quadratic plastic potential function and non-associated flow rule (based on Hill's 1948 model and plastic strain ratios, r-values), and finally some of the cyclic hardening phenomena such as Bauschinger's effect and transient behavior for reverse loading by using a coupled nonlinear kinematic hardening (so-called Armstrong-Frederick-Chaboche model). Basic fundamentals of the plasticity of the model are presented in a general framework. Then, the model adjustment procedure is derived for the plasticity formulations. Also, a generic numerical stress integration procedure is developed based on backward-Euler method (so-called multi-stage return mapping algorithm). Different aspects of the model are verified for DP600 steel sheet. Results show that the new model is able to predict the sheet material behavior in both anisotropic hardening and cyclic hardening regimes more accurately. By featuring the above-mentioned facts in the presented constitutive model, it is expected that more accurate results can be obtained by implementing this model in computational simulations of sheet material forming processes. For instance, more precise results of springback prediction of the parts formed from highly anisotropic hardened materials or that of determining the forming limit diagrams is highly expected by using the developed material model.

  13. Solute hardening and softening effects in B2 nickel aluminides

    SciTech Connect

    Pike, L.M.; Liu, C.T.; Anderson, I.M.; Chang, Y.A.

    1998-11-01

    The effect of substitutional solute additions including Fe, Mn, and Pd on the hardness of B2-ordered NiAl alloys was investigated. The solid solution hardening behavior of intermetallics is more complex than that of typical metallic solid solutions because of complications arising from the site preference of the solute as well as the effects of the solute on the concentrations of other point defects, e.g., vacancies and anti-site defects. For this reason, care was taken to experimentally establish solute site preferences and point defect concentrations in the NiAl alloys before analyzing the hardness data. By taking these factors into account it was possible to rationalize the observed unusual hardening effects. Three distinct categories of solid solution hardening behavior were encountered. The first was hardening by the solute addition itself. This was observed in the case of Pd additions to Al-poor NiAl. However, when fe or Mn is added to Al-poor NiAl a second category is observed; these elements are seen to soften the material. The third category of behavior is observed when Fe is added to NiAl with a constant Al concentration of 50 at. %. In this case it is vacancies, rather than solute atoms, which harden the material.

  14. Dynamic bake hardening of interstitial-free steels

    SciTech Connect

    Dehghani, K.; Jonas, J.J.

    2000-05-01

    Two types of dynamic strain aging (DSA) strengthening methods were investigated to determine their potentials for industrial use. They are referred to here as dynamic-static bake hardening (DSBH) and dynamic bake hardening (DBH). For this purpose, a 0.06 pct Ti interstitial-free (IF) steel was reheated to 900 C and cooled at 12 C/s to room temperature. It was then dynamically bake hardened in the temperature range 100 C to 250 C to strains of 2 to 8 pct at a strain rate of 10{sup {minus}3} s{sup {minus}1}. The tensile properties were determined before and after these treatments. It was found that the occurrence of DSA during dynamic baking led to significant increases in work-hardening rate as well as in the final strength. The results indicate that, for a given solute carbon level, the dynamically and then statically aged samples have higher strengths than those that are bake hardened in the conventional way.

  15. General analytical shakedown solution for structures with kinematic hardening materials

    NASA Astrophysics Data System (ADS)

    Guo, Baofeng; Zou, Zongyuan; Jin, Miao

    2016-04-01

    The effect of kinematic hardening behavior on the shakedown behaviors of structure has been investigated by performing shakedown analysis for some specific problems. The results obtained only show that the shakedown limit loads of structures with kinematic hardening model are larger than or equal to those with perfectly plastic model of the same initial yield stress. To further investigate the rules governing the different shakedown behaviors of kinematic hardening structures, the extended shakedown theorem for limited kinematic hardening is applied, the shakedown condition is then proposed, and a general analytical solution for the structural shakedown limit load is thus derived. The analytical shakedown limit loads for fully reversed cyclic loading and non-fully reversed cyclic loading are then given based on the general solution. The resulting analytical solution is applied to some specific problems: a hollow specimen subjected to tension and torsion, a flanged pipe subjected to pressure and axial force and a square plate with small central hole subjected to biaxial tension. The results obtained are compared with those in literatures, they are consistent with each other. Based on the resulting general analytical solution, rules governing the general effects of kinematic hardening behavior on the shakedown behavior of structure are clearly.

  16. Dithranol as a Matrix for Matrix Assisted Laser Desorption/Ionization Imaging on a Fourier Transform Ion Cyclotron Resonance Mass Spectrometer

    PubMed Central

    Le, Cuong H.; Han, Jun; Borchers, Christoph H.

    2013-01-01

    Mass spectrometry imaging (MSI) determines the spatial localization and distribution patterns of compounds on the surface of a tissue section, mainly using MALDI (matrix assisted laser desorption/ionization)-based analytical techniques. New matrices for small-molecule MSI, which can improve the analysis of low-molecular weight (MW) compounds, are needed. These matrices should provide increased analyte signals while decreasing MALDI background signals. In addition, the use of ultrahigh-resolution instruments, such as Fourier transform ion cyclotron resonance (FTICR) mass spectrometers, has the ability to resolve analyte signals from matrix signals, and this can partially overcome many problems associated with the background originating from the MALDI matrix. The reduction in the intensities of the metastable matrix clusters by FTICR MS can also help to overcome some of the interferences associated with matrix peaks on other instruments. High-resolution instruments such as the FTICR mass spectrometers are advantageous as they can produce distribution patterns of many compounds simultaneously while still providing confidence in chemical identifications. Dithranol (DT; 1,8-dihydroxy-9,10-dihydroanthracen-9-one) has previously been reported as a MALDI matrix for tissue imaging. In this work, a protocol for the use of DT for MALDI imaging of endogenous lipids from the surfaces of mammalian tissue sections, by positive-ion MALDI-MS, on an ultrahigh-resolution hybrid quadrupole FTICR instrument has been provided. PMID:24300588

  17. Comparing Laser Desorption Ionization and Atmospheric Pressure Photoionization Coupled to Fourier Transform Ion Cyclotron Resonance Mass Spectrometry To Characterize Shale Oils at the Molecular Level

    USGS Publications Warehouse

    Cho, Yunjo; Jin, Jang Mi; Witt, Matthias; Birdwell, Justin E.; Na, Jeong-Geol; Roh, Nam-Sun; Kim, Sunghwan

    2013-01-01

    Laser desorption ionization (LDI) coupled to Fourier transform ion cyclotron resonance mass spectrometry (FT-ICR MS) was used to analyze shale oils. Previous work showed that LDI is a sensitive ionization technique for assessing aromatic nitrogen compounds, and oils generated from Green River Formation oil shales are well-documented as being rich in nitrogen. The data presented here demonstrate that LDI is effective in ionizing high-double-bond-equivalent (DBE) compounds and, therefore, is a suitable method for characterizing compounds with condensed structures. Additionally, LDI generates radical cations and protonated ions concurrently, the distribution of which depends upon the molecular structures and elemental compositions, and the basicity of compounds is closely related to the generation of protonated ions. This study demonstrates that LDI FT-ICR MS is an effective ionization technique for use in the study of shale oils at the molecular level. To the best of our knowledge, this is the first time that LDI FT-ICR MS has been applied to shale oils.

  18. Dithranol as a matrix for matrix assisted laser desorption/ionization imaging on a fourier transform ion cyclotron resonance mass spectrometer.

    PubMed

    Le, Cuong H; Han, Jun; Borchers, Christoph H

    2013-01-01

    Mass spectrometry imaging (MSI) determines the spatial localization and distribution patterns of compounds on the surface of a tissue section, mainly using MALDI (matrix assisted laser desorption/ionization)-based analytical techniques. New matrices for small-molecule MSI, which can improve the analysis of low-molecular weight (MW) compounds, are needed. These matrices should provide increased analyte signals while decreasing MALDI background signals. In addition, the use of ultrahigh-resolution instruments, such as Fourier transform ion cyclotron resonance (FTICR) mass spectrometers, has the ability to resolve analyte signals from matrix signals, and this can partially overcome many problems associated with the background originating from the MALDI matrix. The reduction in the intensities of the metastable matrix clusters by FTICR MS can also help to overcome some of the interferences associated with matrix peaks on other instruments. High-resolution instruments such as the FTICR mass spectrometers are advantageous as they can produce distribution patterns of many compounds simultaneously while still providing confidence in chemical identifications. Dithranol (DT; 1,8-dihydroxy-9,10-dihydroanthracen-9-one) has previously been reported as a MALDI matrix for tissue imaging. In this work, a protocol for the use of DT for MALDI imaging of endogenous lipids from the surfaces of mammalian tissue sections, by positive-ion MALDI-MS, on an ultrahigh-resolution hybrid quadrupole FTICR instrument has been provided. PMID:24300588

  19. Glycine Identification in Natural Jarosites Using Laser-Desorption Fourier Transform Mass Spectrometry: Implications for the search for life on Mars

    SciTech Connect

    J. Michelle Kotler; Nancy W. Hinman; Beizhan Yan; Daphne L. Stoner; Jill R. Scott

    2008-04-01

    The jarosite group minerals have received increasing attention since the discovery of jarosite by the Mars Exploration Rover-Opportunity on the Martian surface. The mineral group has the ability to incorporate foreign ions in its structure leading to investigations regarding its use as an indicator of aqueous and/or biological activity on Earth and Mars. The use of laser desorption Fourier transform mass spectrometry has revealed the presence of organic matter in several jarosite samples from various worldwide locations. One of the organic cluster ions has been attributed to glycine based on results from combinations of glycine with synthetic jarosite and K2SO4. The ability to observe these organic signatures in jarosite samples with an “in situ” instrumental technique, such as employed in this study, furthers the goals of planetary geologists to determine whether signs of life (e.g., the presence of biomolecules or biomolecule precursors) can be detected in the rock record of terrestrial and extraterrestrial samples.

  20. A partial least squares and wavelet-transform hybrid model to analyze carbon content in coal using laser-induced breakdown spectroscopy.

    PubMed

    Yuan, Tingbi; Wang, Zhe; Li, Zheng; Ni, Weidou; Liu, Jianmin

    2014-01-01

    A partial least squares (PLS) and wavelet transform hybrid model are proposed to analyze the carbon content of coal by using laser-induced breakdown spectroscopy (LIBS). The hybrid model is composed of two steps of wavelet analysis procedures, which include environmental denoising and background noise reduction, to pretreat the LIBS spectrum. The processed wavelet coefficients, which contain the discrete line information of the spectra, were taken as inputs for the PLS model for calibration and prediction of carbon element. A higher signal-to-noise ratio of carbon line was obtained after environmental denoising, and the best decomposition level was determined after background noise reduction. The hybrid model resulted in a significant improvement over the conventional PLS method under different ambient environments, which include air, argon, and helium. The average relative error of carbon decreased from 2.74 to 1.67% under an ambient helium environment, which indicated a significantly improved accuracy in the measurement of carbon in coal. The best results obtained under an ambient helium environment could be partly attributed to the smallest interference by noise after wavelet denoising. A similar improvement was observed in ambient air and argon environments, thereby proving the applicability of the hybrid model under different experimental conditions. PMID:24356217

  1. Transmission Electron Microscopy and Nanoindentation Study of the Weld Zone Microstructure of Diode-Laser-Joined Automotive Transformation-Induced Plasticity Steel

    NASA Astrophysics Data System (ADS)

    Chen, J.; Sand, K.; Xia, M. S.; Ophus, C.; Mohammadi, R.; Kuntz, M. L.; Zhou, Y.; Mitlin, D.

    2008-03-01

    We have used transmission electron microscopy (TEM) and nanoindentation to characterize the dominant phases present in the weld zone of a diode-laser-welded transformation-induced plasticity (TRIP) steel, examining the unaffected base metal as a baseline. The microstructure of the base metal consists predominantly of ferrite, retained austenite, martensite, and occasional large carbide particles. The dominant microstructure of the weld zone is of differently oriented packets having a bainitic morphology. The weld also contains allotriomorphic ferrite, idiomorphic ferrite, as well some twinned martensite that is surrounded by austenite. The TEM analysis of the bainitic-morphology packets indicates that they consist of a lath ferrite phase separated by an interlath carbon-enriched retained austenite. In most cases, the orientation relationship (OR) between the lath ferrite and the interlath retained austenite can be approximated as Nishiyama Wasserman (N-W). We used site-specific nanoindentation to further characterize the packets and the allotriomorphic ferrite, confirming through the hardness values the conclusions reached by TEM. While martensite was regularly present in the base metal, it was only sparsely distributed within the weld zone, boding well for the weld’s mechanical properties.

  2. Secondary hardening steel having improved combination of hardness and toughness

    DOEpatents

    Parker, Earl R.; Zackay, Victor F.; Bhat, Manjeshwar S.; Garrison, Jr., Warren M.

    1979-01-01

    A secondary hardening alloy steel composition consisting essentially of about 0.25-0.5% carbon, about 0.5-1.0% manganese, about 1.5-3.0% nickel, about 0-1.0% chromium, about 1.75-2.5% molybdenum, about 0-0.4% vanadium, and an additive selected from about 1-3% aluminum and a combination of at least about 1% aluminum and at least about 1% silicon for a combined Al+Si content of about 2-4%, the balance being iron and impurity elements. The present steel composition has the following characteristics: it exhibits a flat tempering response, it is hardenable upon tempering to a Rockwell C hardness of at least 50, and it has an improved combination of hardness vs. toughness properties after tempering in the secondary hardening range. A method of preparation is also described.

  3. Crack resistance of tungsten hardened by dispersed refractory oxides

    SciTech Connect

    Babak, A.V.; Uskov, E.I.

    1985-05-01

    The authors present the results of an investigation of the crack resistance in a wide temperature range of the production types of tungsten VMP-S (conditionally designated technical purity tungsten with a higher degree of deformation than type VMP tungsten), VMP-3 (hardened with refractory oxides), and VMP-4 (with the addition of copper and hardened with refractory oxides) produced using the same method. It is reported that hardening of technical purity tungsten with refractory oxides increases the resistance of the material to crack development in the 20-2000C range, but the upper boundary of the temperature area of the ductile-to-brittle transition is shifted in the direction of higher temperatures, which must be taken into consideration in the use of the investigated alloys as structural materials for objects of new technology.

  4. Oxide dispersion hardened mechanically alloyed materials for high temperatures

    NASA Technical Reports Server (NTRS)

    Benjamin, J. S.; Strassburg, F. W.

    1982-01-01

    The procedure of mechanical alloying makes it possible to obtain, with the aid of powder-metallurgy techniques, alloys that consist of a metallic matrix in which very fine oxide particles are dispersed. Mechanically alloyed compound powders can be used for making either forged or hot-rolled semifinished products. For these products, dispersion strengthening and precipitation hardening has been combined. At high temperatures, the strength characteristics of the alloy are determined by both dispersion hardening and by precipitation hardening processes. The effect produced by each process is independent of that due to the other. Attention is given to the principle of mechanical alloying developed by Benjamin (1970, 1976), the strength characteristics of mechanically alloyed materials, the corrosion resistance of mechanically alloyed material at high temperatures, and the preparation and characteristics of the alloy MA 6000 E.

  5. Engineering design guidelines for electromagnetic pulse hardening of naval equipment

    NASA Astrophysics Data System (ADS)

    Rogers, S. R.; Perala, R. A.; Rosich, R. K.; Cook, R. B.; Rudolph, T. H.

    1981-07-01

    This document is intended to be used by engineers who design and manufacture shipboard equipment. It is complete in the sense that both the EMP hazard and the means of mitigating the hazard (hardening) are presented. The hazard is described, which not only discusses EMP generation in a general sense, but it also presents specific threat levels for EMP fields and transient currents and voltages included on cables and antennas which are connected to electronic equipment. This specific threat constitutes an EMP survivability criteria which must be met by the mission critical equipment. The necessary hardening technology areas include volume shielding, cable shielding and connectors, interface susceptibility analysis, terminal protective devices, upset and upset hardening, common mode rejection techniques, optical isolation, and grounding/bonding techniques. Test techniques which can verify equipment hardness are presented along with methods to observe the equipment's hardness and maintain the hardness.

  6. Hardenability of austenite in a dual-phase steel

    SciTech Connect

    Sarwar, M.; Priestner, R.

    1999-06-01

    A low-carbon, low-alloy steel was intercritically heat treated and thermomechanically processed to study the martensitic hardenability of austenite present. Rolling of the two-phase ({alpha} + {gamma}) microstructure elongated austenite particles and reduced their martensitic hardenability because the {alpha}/{gamma} interface where new ferrite forms during cooling was increased by the particle elongation. The martensite particles obtained in rolled material were also elongated or fibered in the rolling direction. Therefore, the thermomechanical processing of a two-phase ({alpha} + {gamma}) mixture has the detrimental effect of increasing the quenching power needed to yield a specific amount of martensite.

  7. Temperature influence on water transport in hardened cement pastes

    SciTech Connect

    Drouet, Emeline; Poyet, Stéphane; Torrenti, Jean-Michel

    2015-10-15

    Describing water transport in concrete is an important issue for the durability assessment of radioactive waste management reinforced concrete structures. Due to the waste thermal output such structures would be submitted to moderate temperatures (up to 80 °C). We have then studied the influence of temperature on water transport within hardened cement pastes of four different formulations. Using a simplified approach (describing only the permeation of liquid water) we characterized the properties needed to describe water transport (up to 80 °C) using dedicated experiments. For each hardened cement paste the results are presented and discussed.

  8. Statistical thermodynamics of strain hardening in polycrystalline solids

    SciTech Connect

    Langer, James S.

    2015-09-18

    This paper starts with a systematic rederivation of the statistical thermodynamic equations of motion for dislocation-mediated plasticity proposed in 2010 by Langer, Bouchbinder, and Lookman. The paper then uses that theory to explain the anomalous rate-hardening behavior reported in 1988 by Follansbee and Kocks and to explore the relation between hardening rate and grain size reported in 1995 by Meyers et al. A central theme is the need for physics-based, nonequilibrium analyses in developing predictive theories of the strength of polycrystalline materials.

  9. Impact of Scaled Technology on Radiation Testing and Hardening

    NASA Technical Reports Server (NTRS)

    LaBel, Kenneth A.; Cohn, Lewis M.

    2005-01-01

    This presentation gives a brief overview of some of the radiation challenges facing emerging scaled digital technologies with implications on using consumer grade electronics and next generation hardening schemes. Commercial semiconductor manufacturers are recognizing some of these issues as issues for terrestrial performance. Looking at means of dealing with soft errors. The thinned oxide has indicated improved TID tolerance of commercial products hardened by "serendipity" which does not guarantee hardness or say if the trend will continue. This presentation also focuses one reliability implications of thinned oxides.

  10. Statistical thermodynamics of strain hardening in polycrystalline solids

    SciTech Connect

    Langer, James S.

    2015-01-01

    This paper starts with a systematic rederivation of the statistical thermodynamic equations of motion for dislocation-mediated plasticity proposed in 2010 by Langer, Bouchbinder, and Lookman. The paper then uses that theory to explain the anomalous rate-hardening behavior reported in 1988 by Follansbee and Kocks and to explore the relation between hardening rate and grain size reported in 1995 by Meyers et al. A central theme is the need for physics-based, nonequilibrium analyses in developing predictive theories of the strength of polycrystalline materials.

  11. Method and apparatus for welding precipitation hardenable materials

    DOEpatents

    Murray, Jr., Holt; Harris, Ian D.; Ratka, John O.; Spiegelberg, William D.

    1994-01-01

    A method for welding together members consisting of precipitation age hardened materials includes the steps of selecting a weld filler material that has substantially the same composition as the materials being joined, and an age hardening characteristic temperature age threshold below that of the aging kinetic temperature range of the materials being joined, whereby after welding the members together, the resulting weld and heat affected zone (HAZ) are heat treated at a temperature below that of the kinetic temperature range of the materials joined, for obtaining substantially the same mechanical characteristics for the weld and HAZ, as for the parent material of the members joined.

  12. Method and apparatus for welding precipitation hardenable materials

    DOEpatents

    Murray, H. Jr.; Harris, I.D.; Ratka, J.O.; Spiegelberg, W.D.

    1994-06-28

    A method for welding together members consisting of precipitation age hardened materials includes the steps of selecting a weld filler material that has substantially the same composition as the materials being joined, and an age hardening characteristic temperature age threshold below that of the aging kinetic temperature range of the materials being joined, whereby after welding the members together, the resulting weld and heat affected zone (HAZ) are heat treated at a temperature below that of the kinetic temperature range of the materials joined, for obtaining substantially the same mechanical characteristics for the weld and HAZ, as for the parent material of the members joined. 5 figures.

  13. Why semiconductors must be hardened when used in space

    SciTech Connect

    Winokur, P. S.

    2000-01-04

    The natural space radiation environment presents a great challenge to present and future satellite systems with significant assets in space. Defining requirements for such systems demands knowledge about the space radiation environment and its effects on electronics and optoelectronics technologies, as well as suitable risk assessment of the uncertainties involved. For mission of high radiation levels, radiation-hardened integrated circuits will be required to preform critical mission functions. The most successful systems in space will be those that are best able to blend standard commercial electronics with custom radiation-hardened electronics in a mix that is suitable for the system of interest.

  14. Statistical thermodynamics of strain hardening in polycrystalline solids

    NASA Astrophysics Data System (ADS)

    Langer, J. S.

    2015-09-01

    This paper starts with a systematic rederivation of the statistical thermodynamic equations of motion for dislocation-mediated plasticity proposed in 2010 by Langer, Bouchbinder, and Lookman [Acta Mat. 58, 3718 (2010), 10.1016/j.actamat.2010.03.009]. It then uses that theory to explain the anomalous rate-hardening behavior reported in 1988 by Follansbee and Kocks and to explore the relation between hardening rate and grain size reported in 1995 by Meyers et al. A central theme is the need for physics-based, nonequilibrium analyses in developing predictive theories of the strength of polycrystalline materials.

  15. Modelling work hardening of aluminium alloys containing dispersoids

    NASA Astrophysics Data System (ADS)

    Zhao, Qinglong; Holmedal, Bjørn

    2013-08-01

    The influence of dispersoids on tensile deformation behaviour has been studied by comparison of aluminium alloys containing different dispersoid densities. It was found that a fine dispersion of non-shearable particles led to an increased work hardening at the initial plastic deformation, but the effect was opposite at higher strains. The reason has been attributed to the generation of geometrically necessary dislocations (GNDs). A new model has been proposed for the evolution of GNDs based on a balance of storage and dynamic recovery of GNDs. The model predicts a rapid saturation of GNDs and a reduced work hardening at small strains, consistent with the experimental results.

  16. On the hardening and softening of nanocrystalline materials

    SciTech Connect

    Fougere, G.E.; Weertman, J.R. . Dept. of Materials Science and Engineering); Siegel, R.W. . Materials Science Div.)

    1993-04-01

    Nanocrystalline Pd and Cu samples have been thermally treated to determine whether the relation between hardness and grain size depend on the method used to vary the grain sizes. Previous reports indicate that hardening with decreasing grain size resulted from data obtained using individual samples, while softening with decreasing grain size resulted from data from a given sample that had been thermally treated. Hardening and softening regimes were evident for the nanocrystalline cu, and the hardness improvements over the original as-consolidated state were maintained throughout the thermal treatments. This review examines our hardness results for Cu and Pd and those for other nanocrystalline materials.

  17. Fourier Transform Based Deconvolution Analysis of Frequency Modulation Lineshapes; Fluorocarbon Radical Densities in AN Ecr Etcher from Infrared Diode Laser Spectroscopy.

    NASA Astrophysics Data System (ADS)

    Wu, Jian-Zhong

    1995-11-01

    Highly sensitive modulation detection techniques produce a distorted and more complicated form of the original line shape. In this thesis many existing theories for analysis of these modulation lineshapes are mathematically compared. The Fourier transform of the modulation spectrum is shown to be always a product of the Fourier transform of the original spectrum and a known modulation function. If the latter is divided out, then the inverse transform will give the original spectrum as it would have appeared with no modulation. Mathematical expressions of modulation functions are also derived for several more general modulation of waveforms: one-tone frequency modulation by an arbitrary waveform, two-tone frequency modulation (TTFM) by sine waveforms, and tone-burst frequency modulation (TBFM) by sine waveforms. The two seemingly different modulation schemes, TTFM and TBFM, are proven to be actually the same, when no AM is involved and the modulation index is low. Based on the fast Fourier transform (FFT) the deconvolution procedure for one-tone low frequency wavelength modulation has been implemented in FORTRAN. This recovery procedure is applied to some computer simulated modulation spectra of a Gaussian and then to actual multiple line, second harmonic diode laser spectral data taken from a plasma. Also included are infrared absorption measurements of CF, CF_2, CF_3, and COF_2 in an electron cyclotron resonance (ECR) plasma etcher with CHF _3 and rm C_2H_2F _4 as the main feed gases. The role of CF _{x} (x=1, 2, 3) radicals on Si/SiO_2 etch selectivity has been examined by measuring the neutral CF_{x} absolute concentrations in the gas phase for the same sets of conditions employed in etch rate measurements. We have observed P(10.5) and P(11.5) of ^2 Pi_{1/2} and P(10.5) of ^2Pi_{3/2} in the fundamental band of CF in the ECR etcher, and used these transitions in CF absolute density determinations in rm C_2H_2F_4 or CHF_3 in the power range of 500 W to 1200 W and

  18. Hardening effect on machined surface for precise hard cutting process with consideration of tool wear

    NASA Astrophysics Data System (ADS)

    Yue, Caixu; Liu, Xianli; Ma, Jing; Liu, Zhaojing; Liu, Fei; Yang, Yongheng

    2014-11-01

    During hard cutting process there is severe thermodynamic coupling effect between cutting tool and workpiece, which causes quenching effect on finished surfaces under certain conditions. However, material phase transformation mechanism of heat treatment in cutting process is different from the one in traditional process, which leads to changes of the formation mechanism of damaged layer on machined workpiece surface. This paper researches on the generation mechanism of damaged layer on machined surface in the process of PCBN tool hard cutting hardened steel Cr12MoV. Rules of temperature change on machined surface and subsurface are got by means of finite element simulation. In phase transformation temperature experiments rapid transformation instrument is employed, and the effect of quenching under cutting conditions on generation of damaged layer is revealed. Based on that, the phase transformation points of temperature under cutting conditions are determined. By experiment, the effects of cutting speed and tool wear on white layer thickness in damaged layer are revealed. The temperature distribution law of third deformation zone is got by establishing the numerical prediction model, and thickness of white layer in damaged layer is predicted, taking the tool wear effect into consideration. The experimental results show that the model prediction is accurate, and the establishment of prediction model provides a reference for wise selection of parameters in precise hard cutting process. For the machining process with high demanding on surface integrity, the generation of damaged layer on machined surface can be controlled precisely by using the prediction model.

  19. Absolute ν 2 Line Intensities of HOCl by Simultaneous Measurements in the Infrared with a Tunable Diode Laser and Far-Infrared Region Using a Fourier Transform Spectrometer

    NASA Astrophysics Data System (ADS)

    Vander Auwera, J.; Kleffmann, J.; Flaud, J.-M.; Pawelke, G.; Bürger, H.; Hurtmans, D.; Pétrisse, R.

    2000-11-01

    We have measured absolute line intensities in the ν2 fundamental band at 1238 cm-1 of both isotopomers of hypochlorous acid, HOCl. To obtain the partial pressure of the species in the sample mixture, unavailable through direct measurement since HOCl exists only in equilibrium with H2O and Cl2O and may decay by secondary reactions, we relied on known absolute line intensities in the pure rotational far-infrared (FIR) spectrum determined from Stark effect measurements. We have thus recorded simultaneously the FIR pure rotation spectrum of HOCl using a Bruker IFS120HR interferometer and the spectrum of a few vibration-rotation lines in the infrared (IR) ν2 band using a tunable diode laser spectrometer. The absolute intensities of these IR lines thus determined allowed us to 'calibrate' the intensities of vibration-rotation lines in the whole ν2 band, measured previously using Fourier transform spectroscopy. The treatment of the data took into account the blackbody emission contribution in the FIR and the evolution of the HOCl amount during the recording of the spectra. The latter was found to be almost constant over hours after conditioning of the cell. The square of the ν2 band vibrational transition dipole moment was determined to be 0.013947(23) D2 and 0.013870(51) D2 for HO35Cl and HO37Cl, respectively, that is, 29 to 73% lower than previous measurements. A linear Herman-Wallis factor was also determined for both isotopomers. Finally, the line intensities were least-squares fitted using a model that takes into account a weak resonance between the (010) and (002) levels.

  20. A radiation-hardened 16/32-bit microprocessor

    SciTech Connect

    Hass, K.J.; Treece, R.K.; Giddings, A.E.

    1989-01-01

    A radiation-hardened 16/32-bit microprocessor has been fabricated and tested. Our initial evaluation has demonstrated that it is functional after a total gamma dose of 5Mrad(Si) and is immune to SEU from Krypton ions. 3 refs., 2 figs.

  1. 49. INTERIOR VIEW OF HARDENER AREA SHOWING GAUGE THAT MEASURES ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    49. INTERIOR VIEW OF HARDENER AREA SHOWING GAUGE THAT MEASURES HARDNESS, THE NAIL MUST BREAK IN THE CENTER RANGE OF THE CURVED BAR TO HAVE THE CORRECT HARDNESS (THE NAIL WILL BREAK TOO EASILY IF TOO HARD AND WILL BEND TOO MUCH IF TOO SOFT) - LaBelle Iron Works, Thirtieth & Wood Streets, Wheeling, Ohio County, WV

  2. Iterative Beam Hardening Correction for Multi-Material Objects

    PubMed Central

    Zhao, Yunsong; Li, Mengfei

    2015-01-01

    In this paper, we propose an iterative beam hardening correction method that is applicable for the case with multiple materials. By assuming that the materials composing scanned object are known and that they are distinguishable by their linear attenuation coefficients at some given energy, the beam hardening correction problem is converted into a nonlinear system problem, which is then solved iteratively. The reconstructed image is the distribution of linear attenuation coefficient of the scanned object at a given energy. So there are no beam hardening artifacts in the image theoretically. The proposed iterative scheme combines an accurate polychromatic forward projection with a linearized backprojection. Both forward projection and backprojection have high degree of parallelism, and are suitable for acceleration on parallel systems. Numerical experiments with both simulated data and real data verifies the validity of the proposed method. The beam hardening artifacts are alleviated effectively. In addition, the proposed method has a good tolerance on the error of the estimated x-ray spectrum. PMID:26659554

  3. Iterative Beam Hardening Correction for Multi-Material Objects.

    PubMed

    Zhao, Yunsong; Li, Mengfei

    2015-01-01

    In this paper, we propose an iterative beam hardening correction method that is applicable for the case with multiple materials. By assuming that the materials composing scanned object are known and that they are distinguishable by their linear attenuation coefficients at some given energy, the beam hardening correction problem is converted into a nonlinear system problem, which is then solved iteratively. The reconstructed image is the distribution of linear attenuation coefficient of the scanned object at a given energy. So there are no beam hardening artifacts in the image theoretically. The proposed iterative scheme combines an accurate polychromatic forward projection with a linearized backprojection. Both forward projection and backprojection have high degree of parallelism, and are suitable for acceleration on parallel systems. Numerical experiments with both simulated data and real data verifies the validity of the proposed method. The beam hardening artifacts are alleviated effectively. In addition, the proposed method has a good tolerance on the error of the estimated x-ray spectrum. PMID:26659554

  4. An SEU-hardened CMOS data latch design

    SciTech Connect

    Rockett, L.R. Jr.

    1988-12-01

    A Single Event Upset (SEU)-hardened Complementary Metal-Oxide Semiconductor (CMOS) data latch design is described. The hardness is achieved by virtue of the latch design, thus no fabrication process or design groundrule development is required. Hardness is gained with comparatively little adverse impact on performance. Cyclotron tests provided hardness verification.

  5. Overcoming scaling concerns in a radiation-hardening CMOS technology

    SciTech Connect

    Maimon, J.; Haddad, N.

    1999-12-01

    Scaling efforts to develop an advanced radiation-hardened CMOS process to support a 4M SRAM are described. Issues encountered during scaling of transistor, isolation, and resistor elements are discussed, as well as the solutions used to overcome these issues. Transistor data, total dose radiation results, and the performance of novel resistors for prevention of single event upsets (SEU) are presented.

  6. Hardening digital systems with distributed functionality: robust networks

    NASA Astrophysics Data System (ADS)

    Vaskova, Anna; Portela-Garcia, Marta; Garcia-Valderas, Mario; López-Ongil, Celia; Portilla, Jorge; Valverde, Juan; de la Torre, Eduardo; Riesgo, Teresa

    2013-05-01

    Collaborative hardening and hardware redundancy are nowadays the most interesting solutions in terms of fault tolerance achieved and low extra cost imposed to the project budget. Thanks to the powerful and cheap digital devices that are available in the market, extra processing capabilities can be used for redundant tasks, not only in early data processing (sensed data) but also in routing and interfacing1

  7. Beam hardening correction for sparse-view CT reconstruction

    NASA Astrophysics Data System (ADS)

    Liu, Wenlei; Rong, Junyan; Gao, Peng; Liao, Qimei; Lu, HongBing

    2015-03-01

    Beam hardening, which is caused by spectrum polychromatism of the X-ray beam, may result in various artifacts in the reconstructed image and degrade image quality. The artifacts would be further aggravated for the sparse-view reconstruction due to insufficient sampling data. Considering the advantages of the total-variation (TV) minimization in CT reconstruction with sparse-view data, in this paper, we propose a beam hardening correction method for sparse-view CT reconstruction based on Brabant's modeling. In this correction model for beam hardening, the attenuation coefficient of each voxel at the effective energy is modeled and estimated linearly, and can be applied in an iterative framework, such as simultaneous algebraic reconstruction technique (SART). By integrating the correction model into the forward projector of the algebraic reconstruction technique (ART), the TV minimization can recover images when only a limited number of projections are available. The proposed method does not need prior information about the beam spectrum. Preliminary validation using Monte Carlo simulations indicates that the proposed method can provide better reconstructed images from sparse-view projection data, with effective suppression of artifacts caused by beam hardening. With appropriate modeling of other degrading effects such as photon scattering, the proposed framework may provide a new way for low-dose CT imaging.

  8. Review of radiation hardening techniques for EDFAs in space environment

    NASA Astrophysics Data System (ADS)

    Wang, Qian; Tian, CuiPing; Wang, YingYing; Wang, Pu

    2015-03-01

    The damage mechanism and test technology of space radiation environment to space equipment was classified and the radiation protection demand of active fiber for space application was analyzed. The radiation hardening techniques of Ce doping, hydrogen loading and pre-radiation exposure and thermal annealing for Er:Yb co-doped fiber was surveyed.

  9. Total dose performance of radiation hardened voltage regulators and references

    NASA Technical Reports Server (NTRS)

    McClure, S.; Gorelick, J.; Pease, R.; Rax, B.; Ladbury, R.

    2001-01-01

    Total dose test of commercially available radiation hardened bipolar voltage regulators and references show reduced sensitivity to dose rate and varying sensitivity to bias under pressure. Behavior of critical parameters in different dose rate and bias conditions is compared and the impact to hardness assurance methodology is discussed.

  10. SEGR response of a radiation-hardened power MOSFET technology

    SciTech Connect

    Wheatley, C.F.; Titus, J.L.; Burton, D.I.; Carley, D.R.

    1996-12-01

    SEGR response curves are presented for eighteen different device types of radiation-hardened power MOSFETs. Comparisons are made to demonstrate the technology`s insensitivity to die size, rated blocking voltage, channel conductivity, and temperature. From this data, SEGR cross-sectional area curves are inferred.

  11. Fourier Transform Spectrometer System

    NASA Technical Reports Server (NTRS)

    Campbell, Joel F. (Inventor)

    2014-01-01

    A Fourier transform spectrometer (FTS) data acquisition system includes an FTS spectrometer that receives a spectral signal and a laser signal. The system further includes a wideband detector, which is in communication with the FTS spectrometer and receives the spectral signal and laser signal from the FTS spectrometer. The wideband detector produces a composite signal comprising the laser signal and the spectral signal. The system further comprises a converter in communication with the wideband detector to receive and digitize the composite signal. The system further includes a signal processing unit that receives the composite signal from the converter. The signal processing unit further filters the laser signal and the spectral signal from the composite signal and demodulates the laser signal, to produce velocity corrected spectral data.

  12. Effect of Quenching Rate on Distortion and Residual Stresses During Induction Hardening of a Full-Float Truck Axle Shaft

    NASA Astrophysics Data System (ADS)

    Li, Zhichao; Ferguson, B. Lynn; Nemkov, Valentin; Goldstein, Robert; Jackowski, John; Fett, Greg

    2014-12-01

    Computer simulation is used to predict the residual stresses and distortion of a full-float truck axle shaft that has been induction scan hardened. Flux2D® is used to model the electromagnetic behavior and the power distributions inside the axle shaft in terms of time. The power distributions are imported and mapped into DANTE® model for thermal, phase transformation, and stress analysis. The truck axle shaft has three main geometrical regions: the flange/filet, the shaft, and the spline. Both induction heating and spray quenching processes have significant effect on the quenching results: distortion and residual stress distributions. In this study, the effects of spray quenching severity on residual stresses and distortion are investigated using modeling. The spray quenching rate can be adjusted by spray nozzle design, ratio of polymer solution, and quenchant flow rate. Different quenching rates are modeled by assigning different heat transfer coefficients as thermal boundary conditions during spray quenching. In this paper, three heat transfer coefficients, 5, 12, and 25 kW/(m2 °C), are applied while keeping all other conditions constant. With the understanding of effects of heating and quenching on residual stresses and distortion of induction hardened parts, the induction hardening process can be optimized for improved part performance.

  13. Nanoscale characterization of the biomechanical hardening of bovine zona pellucida.

    PubMed

    Boccaccio, Antonio; Frassanito, Maria Cristina; Lamberti, Luciano; Brunelli, Roberto; Maulucci, Giuseppe; Monaci, Maurizio; Papi, Massimiliano; Pappalettere, Carmine; Parasassi, Tiziana; Sylla, Lakamy; Ursini, Fulvio; De Spirito, Marco

    2012-11-01

    The zona pellucida (ZP) is an extracellular membrane surrounding mammalian oocytes. The so-called zona hardening plays a key role in fertilization process, as it blocks polyspermy, which may also be caused by an increase in the mechanical stiffness of the ZP membrane. However, structural reorganization mechanisms leading to ZP's biomechanical hardening are not fully understood yet. Furthermore, a correct estimate of the elastic properties of the ZP is still lacking. Therefore, the aim of the present study was to investigate the biomechanical behaviour of ZP membranes extracted from mature and fertilized bovine oocytes to better understand the mechanisms involved in the structural reorganization of the ZP that may lead to the biomechanical hardening of the ZP. For that purpose, a hybrid procedure is developed by combining atomic force microscopy nanoindentation measurements, nonlinear finite element analysis and nonlinear optimization. The proposed approach allows us to determine the biomechanical properties of the ZP more realistically than the classical analysis based on Hertz's contact theory, as it accounts for the nonlinearity of finite indentation process, hyperelastic behaviour and material heterogeneity. Experimental results show the presence of significant biomechanical hardening induced by the fertilization process. By comparing various hyperelastic constitutive models, it is found that the Arruda-Boyce eight-chain model best describes the biomechanical response of the ZP. Fertilization leads to an increase in the degree of heterogeneity of membrane elastic properties. The Young modulus changes sharply within a superficial layer whose thickness is related to the characteristic distance between cross-links in the ZP filamentous network. These findings support the hypothesis that biomechanical hardening of bovine ZP is caused by an increase in the number of inter-filaments cross-links whose density should be higher in the ZP inner side. PMID:22675161

  14. Forming an age hardenable aluminum alloy with intermediate annealing

    NASA Astrophysics Data System (ADS)

    Wang, Kaifeng; Carsley, John E.; Stoughton, Thomas B.; Li, Jingjing; Zhang, Lianhong; He, Baiyan

    2013-12-01

    A method to improve formability of aluminum sheet alloys by a two-stage stamping process with intermediate annealing was developed for a non-age hardenable Al-Mg alloy where the annealing heat treatment provided recovery of cold work from the initial stamping and recrystallization of the microstructure to enhance the forming limits of the material. This method was extended to an age hardenable, Al-Mg-Si alloy, which is complicated by the competing metallurgical effects during heat treatment including recovery (softening effect) vs. precipitation (hardening effect). An annealing heat treatment process condition was discovered wherein the stored strain energy from an initial plastic deformation can be sufficiently recovered to enhance formability in a second deformation; however, there is a deleterious effect on subsequent precipitation hardening. The improvement in formability was quantified with uniaxial tensile tests as well as with the forming limit diagram. Since strain-based forming limit curves (FLC) are sensitive to pre-strain history, both stress-based FLCs and polar-effective-plastic-strain (PEPS) FLCs, which are path-independent, were used to evaluate the forming limits after preform annealing. A technique was developed to calculate the stress-based FLC in which a residual-effective-plastic-strain (REPS) was determined by overlapping the hardening curve of the pre-strained and annealed material with that of the simply-annealed- material. After converting the strain-based FLCs using the constant REPS method, it was found that the stress-based FLCs and the PEPS FLCs of the post-annealed materials were quite similar and both tools are applicable for evaluating the forming limits of Al-Mg-Si alloys for a two-step stamping process with intermediate annealing.

  15. Gradient boride layers formed by diffusion carburizing and laser boriding

    NASA Astrophysics Data System (ADS)

    Kulka, M.; Makuch, N.; Dziarski, P.; Mikołajczak, D.; Przestacki, D.

    2015-04-01

    Laser boriding, instead of diffusion boriding, was proposed to formation of gradient borocarburized layers. The microstructure and properties of these layers were compared to those-obtained after typical diffusion borocarburizing. First method of treatment consists in diffusion carburizing and laser boriding only. In microstructure three zones are present: laser borided zone, hardened carburized zone and carburized layer without heat treatment. However, the violent decrease in the microhardness was observed below the laser borided zone. Additionally, these layers were characterized by a changeable value of mass wear intensity factor thus by a changeable abrasive wear resistance. Although at the beginning of friction the very low values of mass wear intensity factor Imw were obtained, these values increased during the next stages of friction. It can be caused by the fluctuations in the microhardness of the hardened carburized zone (HAZ). The use of through hardening after carburizing and laser boriding eliminated these fluctuations. Two zones characterized the microstructure of this layer: laser borided zone and hardened carburized zone. Mass wear intensity factor obtained a constant value for this layer and was comparable to that-obtained in case of diffusion borocarburizing and through hardening. Therefore, the diffusion boriding could be replaced by the laser boriding, when the high abrasive wear resistance is required. However, the possibilities of application of laser boriding instead of diffusion process were limited. In case of elements, which needed high fatigue strength, the substitution of diffusion boriding by laser boriding was not advisable. The surface cracks formed during laser re-melting were the reason for relatively quickly first fatigue crack. The preheating of the laser treated surface before laser beam action would prevent the surface cracks and cause the improved fatigue strength. Although the cohesion of laser borided carburized layer was

  16. Selective Emitter Pumped Rare Earth Laser

    NASA Technical Reports Server (NTRS)

    Chubb, Donald L. (Inventor); Patton, Martin O. (Inventor)

    2001-01-01

    A selective emitter pumped rare earth laser provides an additional type of laser for use in many laser applications. Rare earth doped lasers exist which are pumped with flashtubes or laser diodes. The invention uses a rare earth emitter to transform thermal energy input to a spectral band matching the absorption band of a rare earth in the laser in order to produce lasing.

  17. Age hardening of 6061/alumina-silica fiber composite

    SciTech Connect

    Khangaonkar, P.R.; Shamsul, J.B.; Azmi, R.

    1994-12-31

    Continuous alumina-silica fiber (Altex of Sumitomo) which yields high performance composites with some aluminium alloys was tried for squeeze cast 6061 based composites with volume fractions of 0.5 and 0.32, and the matrix microhardness and resistivity changes during age hardening were studied. The matrix in the composites hardened much more than the unreinforced alloy. Microhardness increases of up to 70 VPN above the solution treated condition at various aging temperatures were observed. The resistivity variation indicated an appreciable state of internal stress which continued to persist even when hardness fell by overaging. Energy dispersive X-ray analysis indicated that the regions close to the fibers had a higher silicon content than the matrix, and amorphous silica in the fiber may have a role in the formation of an enriched layer which may help the bonding and strength in the composite.

  18. ORIGIN OF THE COSMIC-RAY SPECTRAL HARDENING

    SciTech Connect

    Tomassetti, Nicola

    2012-06-10

    Recent data from ATIC, CREAM, and PAMELA indicate that the cosmic-ray energy spectra of protons and nuclei exhibit a remarkable hardening at energies above 100 GeV nucleon{sup -1}. We propose that the hardening is an interstellar propagation effect that originates from a spatial change of the cosmic-ray transport properties in different regions of the Galaxy. The key hypothesis is that the diffusion coefficient is not separable into energy and space variables as usually assumed. Under this scenario, we can reproduce the observational data well. Our model has several implications for cosmic-ray acceleration/propagation physics and can be tested by ongoing experiments such as the Alpha Magnetic Spectrometer or Fermi-LAT.

  19. Hardening electronic devices against very high total dose radiation environments

    NASA Technical Reports Server (NTRS)

    Buchanan, B.; Shedd, W.; Roosild, S.; Dolan, R.

    1972-01-01

    The possibilities and limitations of hardening silicon semiconductor devices to the high neutron and gamma radiation levels and greater than 10 to the eighth power rads required for the NERVA nuclear engine development are discussed. A comparison is made of the high dose neutron and gamma hardening potential of bipolar, metal insulator semiconductors and junction field effect transistors. Experimental data is presented on device degradation for the high neutron and gamma doses. Previous data and comparisons indicate that the JFET is much more immune to the combined neutron displacement and gamma ionizing effects than other transistor types. Experimental evidence is also presented which indicates that p channel MOS devices may be able to meet the requirements.

  20. A Brief Discussion of Radiation Hardening of CMOS Microelectronics

    SciTech Connect

    Myers, D.R.

    1998-12-18

    Commercial microchips work well in their intended environments. However, generic microchips will not fimction correctly if exposed to sufficient amounts of ionizing radiation, the kind that satellites encounter in outer space. Modern CMOS circuits must overcome three specific concerns from ionizing radiation: total-dose, single-event, and dose-rate effects. Minority-carrier devices such as bipolar transistors, optical receivers, and solar cells must also deal with recombination-generation centers caused by displacement damage, which are not major concerns for majority-carrier CMOS devices. There are ways to make the chips themselves more resistant to radiation. This extra protection, called radiation hardening, has been called both a science and an art. Radiation hardening requires both changing the designs of the chips and altering the ways that the chips are manufactured.

  1. Segmentation-free empirical beam hardening correction for CT

    SciTech Connect

    Schüller, Sören; Sawall, Stefan; Stannigel, Kai; Hülsbusch, Markus; Ulrici, Johannes; Hell, Erich; Kachelrieß, Marc

    2015-02-15

    Purpose: The polychromatic nature of the x-ray beams and their effects on the reconstructed image are often disregarded during standard image reconstruction. This leads to cupping and beam hardening artifacts inside the reconstructed volume. To correct for a general cupping, methods like water precorrection exist. They correct the hardening of the spectrum during the penetration of the measured object only for the major tissue class. In contrast, more complex artifacts like streaks between dense objects need other techniques of correction. If using only the information of one single energy scan, there are two types of corrections. The first one is a physical approach. Thereby, artifacts can be reproduced and corrected within the original reconstruction by using assumptions in a polychromatic forward projector. These assumptions could be the used spectrum, the detector response, the physical attenuation and scatter properties of the intersected materials. A second method is an empirical approach, which does not rely on much prior knowledge. This so-called empirical beam hardening correction (EBHC) and the previously mentioned physical-based technique are both relying on a segmentation of the present tissues inside the patient. The difficulty thereby is that beam hardening by itself, scatter, and other effects, which diminish the image quality also disturb the correct tissue classification and thereby reduce the accuracy of the two known classes of correction techniques. The herein proposed method works similar to the empirical beam hardening correction but does not require a tissue segmentation and therefore shows improvements on image data, which are highly degraded by noise and artifacts. Furthermore, the new algorithm is designed in a way that no additional calibration or parameter fitting is needed. Methods: To overcome the segmentation of tissues, the authors propose a histogram deformation of their primary reconstructed CT image. This step is essential for the

  2. Precipitation hardening in a dental low-gold alloy.

    PubMed

    Kim, Hyung-Il; Park, Young-Hwan; Lee, Hee-Kyung; Seol, Hyo-Joung; Shiraishi, Takanobu; Hisatsune, Kunihiro

    2003-03-01

    Age-hardening characteristics in a dental low-gold alloy composed of 40.0 wt% Au-35.0 wt% Ag-7.9 wt% Pd-7.0 wt% Cu-5.0 wt% In-3.5 wt% Zn-1.5 wt% Sn, were investigated by means of the hardness test, XRD study, SEM observations and EPMA. The following results were obtained. The age-hardening was characterized by a precipitation of Cu-rich alpha2 phase in the a phase. The softening that occurred following prolonged ageing was due to the heterogeneous formation of the fine nodular precipitates composed of the Ag-rich alpha1 phase and the Cu-rich alpha2 phase at the grain boundaries of the a phase. PMID:12790292

  3. Magnetic hardening in FePt nanostructured films

    SciTech Connect

    Liu, J.P.; Liu, Y.; Luo, C.P.; Shan, Z.S.; Sellmyer, D.J.

    1997-04-01

    FePt films have been prepared by sputtering Fe/Pt multilayers onto glass or silicon substrates. The thickness of the Fe and Pt layers was adjusted with the Fe:Pt atomic ratio from about 1:1 to 2:1. Magnetic hardening is observed after heat treatment at elevated temperatures, which led to coercivity values exceeding 20 kOe in samples with an Fe:Pt ratio around 1.2:1. The hardening originates from the formation of the tetragonal FePt phase with high magnetocrystalline anisotropy and a favorable microstructure. Two-phase composite films containing hard and soft phases were obtained when the Fe:Pt ratio increased. Under optimized processing conditions, composite films with energy products larger than 30 MGOe at room temperature have been successfully produced. {copyright} {ital 1997 American Institute of Physics.}

  4. Magnetic hardening in FePt nanostructured films

    NASA Astrophysics Data System (ADS)

    Liu, J. P.; Liu, Y.; Luo, C. P.; Shan, Z. S.; Sellmyer, D. J.

    1997-04-01

    FePt films have been prepared by sputtering Fe/Pt multilayers onto glass or silicon substrates. The thickness of the Fe and Pt layers was adjusted with the Fe:Pt atomic ratio from about 1:1 to 2:1. Magnetic hardening is observed after heat treatment at elevated temperatures, which led to coercivity values exceeding 20 kOe in samples with an Fe:Pt ratio around 1.2:1. The hardening originates from the formation of the tetragonal FePt phase with high magnetocrystalline anisotropy and a favorable microstructure. Two-phase composite films containing hard and soft phases were obtained when the Fe:Pt ratio increased. Under optimized processing conditions, composite films with energy products larger than 30 MG Oe at room temperature have been successfully produced.

  5. CMOS inverter design-hardened to the total dose effect

    SciTech Connect

    Roche, F.M.; Salager, L.

    1996-12-01

    This paper reports and discusses the experimental behavior of two inverter structures Rad-Hardened by Design to {sup 60}Co irradiation. The authors use the results on a set of basic circuits and transistors exposed to the same total doses as these structures to establish the effective formation conditions of the parasitic channel. Then this leakage evolution is related to the gate voltage history under irradiation. Finally, they take advantage of this intrinsic degradation property to propose a new Design Rad Hardened (DRH) cell. This structure considerably limits the Low Noise Margin degradation, helps to maintain the logic functionality with a High Output level and improves both the rad-tolerance and the static power consumption.

  6. Springback After the Lateral Bending of T-Section Rails of Work-Hardening Materials

    NASA Astrophysics Data System (ADS)

    Song, Youshuo; Yu, Zhonghua

    2013-11-01

    This paper studies the springback after the lateral bending of T-section rails, considering the work-hardening materials. A linear-hardening model and an elastic-plastic power-exponent hardening model of the material are adopted and compared with the real experimental stress-strain curve obtained from the uniaxial tension tests. The analytical formulas for the springback and residual curvatures are given. The numerical results indicate that the material hardening directly affects the accuracy of springback prediction compared with the experimental results. Besides, springback prediction is not sensitive to hardening parameters in the beginning of elastic-plastic bending deformation. Although there is an apparent yield stage in the true stress-strain curve, the adopted hardening models can achieve an allowable relative error, if hardening parameters are properly selected.

  7. Surface hardening of titanium alloys with melting depth controlled by heat sink

    DOEpatents

    Oden, Laurance L.; Turner, Paul C.

    1995-01-01

    A process for forming a hard surface coating on titanium alloys includes providing a piece of material containing titanium having at least a portion of one surface to be hardened. The piece having a portion of a surface to be hardened is contacted on the backside by a suitable heat sink such that the melting depth of said surface to be hardened may be controlled. A hardening material is then deposited as a slurry. Alternate methods of deposition include flame, arc, or plasma spraying, electrodeposition, vapor deposition, or any other deposition method known by those skilled in the art. The surface to be hardened is then selectively melted to the desired depth, dependent on the desired coating thickness, such that a molten pool is formed of the piece surface and the deposited hardening material. Upon cooling a hardened surface is formed.

  8. Chemical lasers

    NASA Astrophysics Data System (ADS)

    Khariton, Y.

    1984-08-01

    The application and the advances of quantum electronics, specifically, of optical quantum generators lasers is reviewed. Materials are cut, their surfaces are machined, chemical transformations of substances are carried out, surgical operations are performed, data are transmitted, three dimensional images are produced and the content of microimpurities, in the atmosphere, are analyzed by use of a beam. Laser technology is used in conducting investigations in the most diverse fields of the natural and technical sciences from controlled thermonuclear fusion to genetics. Many demands are placed on lasers as sources of light energy. The importance of low weight, compactness of the optical generator and the efficiency of energy conversion processes is emphasized.

  9. A beam hardening correction method based on HL consistency

    NASA Astrophysics Data System (ADS)

    Mou, Xuanqin; Tang, Shaojie; Yu, Hengyong

    2006-08-01

    XCT with polychromatic tube spectrum causes artifact called beam hardening effect. The current correction in CT device is carried by apriori polynomial from water phantom experiment. This paper proposes a new beam hardening correction algorithm that the correction polynomial depends on the relativity of projection data in angles, which obeys Helgasson-Ludwig Consistency (HL Consistency). Firstly, a bi-polynomial is constructed to characterize the beam hardening effect based on the physical model of medical x-ray imaging. In this bi-polynomial, a factor r(γ,β) represents the ratio of the attenuation contributions caused by high density mass (bone, etc.) to low density mass (muscle, vessel, blood, soft tissue, fat, etc.) respectively in the projection angle β and fan angle γ. Secondly, let r(γ,β)=0, the bi-polynomial is degraded as a sole-polynomial. The coefficient of this polynomial can be calculated based on HL Consistency. Then, the primary correction is reached, which is also more efficient in theoretical than the correction method in current CT devices. Thirdly, based on the result of a normal CT reconstruction from the corrected projection data, r(γ,β) can be estimated. Fourthly, the coefficient of bi-polynomial can also be calculated based HL Consistency and the final correction are achieved. Experiments of circular cone beam CT indicate this method an excellent property. Correcting beam hardening effect based on HL Consistency, not only achieving a self-adaptive and more precise correction, but also getting rid of regular inconvenient water phantom experiments, will renovate the correction technique of current CT devices.

  10. Hardening of commercial CMOS PROMs with polysilicon fusible links

    NASA Technical Reports Server (NTRS)

    Newman, W. H.; Rauchfuss, J. E.

    1985-01-01

    The method by which a commercial 4K CMOS PROM with polysilicon fuses was hardened and the feasibility of applying this method to a 16K PROM are presented. A description of the process and the necessary minor modifications to the original layout are given. The PROM circuit and discrete device characteristics over radiation to 1000K rad-Si are summarized. The dose rate sensitivity of the 4K PROMs is also presented.

  11. Structural influences on the work hardening behavior of aluminum

    SciTech Connect

    Chu, D.

    1994-12-01

    Effects of various grain and subgrain morphologies on low temperature work hardening of pure Al is studied using tensile tests. Plotting the work hardening rate as a function of true stress, the work hardening is separable into two distinct regimes. Both regimes are approximated by a line {Theta} = {Theta}{sub 0} {minus} K{sub 2}{sigma}, where {Theta}{sub 0} is theoretical work hardening rate at zero stress and K{sub 2} is related to dynamic recovery rate. The first or early deformation regime exhibits greater values of {Theta}{sub 0} and K{sub 2} and can extend up to the first 10% strain of tensile deformation. This early deformation regime is contingent on the existence of a pre-existent dislocation substructure from previous straining. The {Theta}{sub 0} and K{sub 2} associated with the early deformation regime are dependent on the strength and orientation of the pre-existent dislocation substructure relative to the new strain path. At high enough temperatures, this pre-existent dislocation substructure is annealed out, resulting in the near elimination of the early deformation regime. In comparison, the latter regime is dominated by the initial grain and/or subgrain morphology and exhibit lower values of {Theta}{sub 0} and K{sub 2}. The actual value of K{sub 2} in the latter regime is strongly dependent on the existence of a subgrain morphology. Recrystallized or well-annealed microstructures exhibit greater values of K{sub 2} than microstructures that remain partially or fully unrecrystallized. The higher K{sub 2} value is indicative of a more rapid dynamic recovery rate and a greater degree of strain relaxation. The ability to achieve a more relaxed state produces a low-energy cellular dislocation substructure upon deformation. The introduction of subgrains hinders the evolution of a low-energy dislocation cell network, giving way to a more random distribution of the dislocation density.

  12. Sequential circuit design for radiation hardened multiple voltage integrated circuits

    DOEpatents

    Clark, Lawrence T.; McIver, III, John K.

    2009-11-24

    The present invention includes a radiation hardened sequential circuit, such as a bistable circuit, flip-flop or other suitable design that presents substantial immunity to ionizing radiation while simultaneously maintaining a low operating voltage. In one embodiment, the circuit includes a plurality of logic elements that operate on relatively low voltage, and a master and slave latches each having storage elements that operate on a relatively high voltage.

  13. Single cell mechanics: stress stiffening and kinematic hardening.

    PubMed

    Fernández, Pablo; Ott, Albrecht

    2008-06-13

    Cell mechanical properties are fundamental to the organism but remain poorly understood. We report a comprehensive phenomenological framework for the complex rheology of single fibroblast cells: a superposition of elastic stiffening and viscoplastic kinematic hardening. Despite the complexity of the living cell, its mechanical properties can be cast into simple, well-defined rules. Our results reveal the key role of crosslink slippage in determining mechanical cell strength and robustness. PMID:18643547

  14. The Technology of Mould Steel for Online Pre-hardening

    NASA Astrophysics Data System (ADS)

    Zhu, Dongmei; Liu, Guoyong; Li, Mouwei; Zhang, Shaojun; Bian, Xinxiao; Wanglin; Quan, Wang; Dai, Jinguo; Xubin; Wei, Chaocheng; Cai, Lijuan; Liu, Zuofeng; Gong, Shichuang; An, Zhengang

    This article describes a production method of mould steel pre-hardening, and focus on the advantage of this method, The technical core of method is the variable frequency and variable amplitude pulse uniform high-precision temperature control, which achieved by using strong-medium-weak water cooling, gas-water cooling and gas mist cooling composite cooling control technology. Optimizing the cooling rate path is a good method of optimizing quenched organization and structure.

  15. Reduction of metal artifacts: beam hardening and photon starvation effects

    NASA Astrophysics Data System (ADS)

    Yadava, Girijesh K.; Pal, Debashish; Hsieh, Jiang

    2014-03-01

    The presence of metal-artifacts in CT imaging can obscure relevant anatomy and interfere with disease diagnosis. The cause and occurrence of metal-artifacts are primarily due to beam hardening, scatter, partial volume and photon starvation; however, the contribution to the artifacts from each of them depends on the type of hardware. A comparison of CT images obtained with different metallic hardware in various applications, along with acquisition and reconstruction parameters, helps understand methods for reducing or overcoming such artifacts. In this work, a metal beam hardening correction (BHC) and a projection-completion based metal artifact reduction (MAR) algorithms were developed, and applied on phantom and clinical CT scans with various metallic implants. Stainless-steel and Titanium were used to model and correct for metal beam hardening effect. In the MAR algorithm, the corrupted projection samples are replaced by the combination of original projections and in-painted data obtained by forward projecting a prior image. The data included spine fixation screws, hip-implants, dental-filling, and body extremity fixations, covering range of clinically used metal implants. Comparison of BHC and MAR on different metallic implants was used to characterize dominant source of the artifacts, and conceivable methods to overcome those. Results of the study indicate that beam hardening could be a dominant source of artifact in many spine and extremity fixations, whereas dental and hip implants could be dominant source of photon starvation. The BHC algorithm could significantly improve image quality in CT scans with metallic screws, whereas MAR algorithm could alleviate artifacts in hip-implants and dentalfillings.

  16. Elastic constant versus temperature behavior of three hardened maraging steels

    NASA Technical Reports Server (NTRS)

    Ledbetter, H. M.; Austin, M. W.

    1985-01-01

    Elastic constants of three maraging steels were determined by measuring ultrasonic velocities. Annealed steels show slightly lower bulk moduli and considerably lower shear moduli than hardened steels. All the elastic constants (Young's modulus, shear modulus, bulk modulus and Poisson's ratio) show regular temperature behavior between 76 and 400 K. Young's modulus and the shear modulus increase with increasing yield strength, but the bulk modulus and Poisson's ratio are relatively unchanged. Elastic anisotropy is quite small.

  17. Control technology for surface treatment of materials using induction hardening

    SciTech Connect

    Kelley, J.B.; Skocypec, R.D.

    1997-04-01

    In the industrial and automotive industries, induction case hardening is widely used to provide enhanced strength, wear resistance, and toughness in components made from medium and high carbon steels. The process uses significantly less energy than competing batch process, is environmentally benign, and is a very flexible in-line manufacturing process. As such, it can directly contribute to improved component reliability, and the manufacture of high-performance lightweight parts. However, induction hardening is not as widely used as it could be. Input material and unexplained process variations produce significant variation in product case depth and quality. This necessitates frequent inspection of product quality by destructive examination, creates higher than desired scrap rates, and causes de-rating of load stress sensitive components. In addition, process and tooling development are experience-based activities, accomplished by trial and error. This inhibits the use of induction hardening for new applications, and the resultant increase in energy efficiency in the industrial sectors. In FY96, a Cooperative Research and Development Agreement under the auspices of the Technology Transfer Initiative and the Partnership for a New Generation of Vehicles was completed. A multidisciplinary team from Sandia National Labs and Delphi Saginaw Steering Systems investigated the induction hardening by conducting research in the areas of process characterization, computational modeling, materials characterization, and high speed data acquisition and controller development. The goal was to demonstrate the feasibility of closed-loop control for a specific material, geometry, and process. Delphi Steering estimated annual savings of $2-3 million per year due to reduced scrap losses, inspection costs, and machine down time if reliable closed-loop control could be achieved. A factor of five improvement in process precision was demonstrated and is now operational on the factory floor.

  18. Influence of Pre-straining and Heat Treatment on the Yield Surface of Precipitation Hardenable Aluminum Alloys

    NASA Astrophysics Data System (ADS)

    Lechner, Michael; Johannes, Maren; Kuppert, Andreas; Merklein, Marion

    Precipitation hardenable aluminum alloys are some of the most important lightweight materials. However, their range of applications in comparison to conventional deep drawing steels is limited by the low formability. Therefore, a new and innovative approach to enhance the formability of aluminum alloys in multistage forming operations was invented at the Institute of Manufacturing Technology, called intermediate heat treatment (IHT). Based on a short-term, laser-assisted heat treatment between two forming steps, it is possible to locally adapt the mechanical properties and realize an optimized strength distribution. For the successful application of the technology, the influence of the heat treatment on the mechanical properties has to be analyzed. Concerning the simulation of a multistage forming process, in particular, the yield surface of the material is very important. Within this paper, the influence of a combined pre-straining and a subsequent short-term, laser-assisted heat treatment on the yield surface will be presented.

  19. Description of full-range strain hardening behavior of steels.

    PubMed

    Li, Tao; Zheng, Jinyang; Chen, Zhiwei

    2016-01-01

    Mathematical expression describing plastic behavior of steels allows the execution of parametric studies for many purposes. Various formulas have been developed to characterize stress strain curves of steels. However, most of those formulas failed to describe accurately the strain hardening behavior of steels in the full range which shows various distinct stages. For this purpose, a new formula is developed based on the well-known Ramberg-Osgood formula to describe the full range strain hardening behavior of steels. Test results of all the six types of steels show a three-stage strain hardening behavior. The proposed formula can describe such behavior accurately in the full range using a single expression. The parameters of the formula can be obtained directly and easily through linear regression analysis. Excellent agreements with the test data are observed for all the steels tested. Furthermore, other formulas such as Ludwigson formula, Gardner formula, UGent formula are also applied for comparison. Finally, the proposed formula is considered to have wide suitability and high accuracy for all the steels tested. PMID:27563511

  20. Study on boring hardened materials dryly by ultrasonic vibration cutter

    NASA Astrophysics Data System (ADS)

    Zhang, Jiangzhong; Zhang, Heng; Zhang, Yue

    2011-05-01

    It has been one of the difficulties that high-precision hole on hardened materials is machined. The supersonic vibration boring acoustic system in the lathe in which supersonic wave energy is applied on tool is introduced to create pulse power on the cutting process. The separation vibration cutting is achieved by the pulse force. The comparative tests on boring accuracy and surface quality are carried. The quality of surface machined by this method is compared to that by grinding. This cutting is the green cutting. The boring process system is stability. Under the condition that the cutting speed is less than or equal to 1/3 the tool vibration speed, the cutting force is pulse force and the Cutting energy is of high concentration in time, space and direction. The pulse energy effects on the cutting unit in less than one ten-thousandth second. Traditional cutting of irregular movement elastic compression are eliminated. The cutting force is greatly reduced. The cutting temperature is at room temperature. The tool life is greatly increased. Shape precision and surface quality is greatly improved. The regulations of the ultrasonic vibration boring dry cutting of hardened material are also summarized. The test results show that the ultrasonic vibration cutting tool boring is of very superior cutting mechanism and is a high-precision deep-hole machining of hardened materials, efficient cutting methods.

  1. Study on boring hardened materials dryly by ultrasonic vibration cutter

    NASA Astrophysics Data System (ADS)

    Zhang, Jiangzhong; Zhang, Heng; Zhang, Yue

    2010-12-01

    It has been one of the difficulties that high-precision hole on hardened materials is machined. The supersonic vibration boring acoustic system in the lathe in which supersonic wave energy is applied on tool is introduced to create pulse power on the cutting process. The separation vibration cutting is achieved by the pulse force. The comparative tests on boring accuracy and surface quality are carried. The quality of surface machined by this method is compared to that by grinding. This cutting is the green cutting. The boring process system is stability. Under the condition that the cutting speed is less than or equal to 1/3 the tool vibration speed, the cutting force is pulse force and the Cutting energy is of high concentration in time, space and direction. The pulse energy effects on the cutting unit in less than one ten-thousandth second. Traditional cutting of irregular movement elastic compression are eliminated. The cutting force is greatly reduced. The cutting temperature is at room temperature. The tool life is greatly increased. Shape precision and surface quality is greatly improved. The regulations of the ultrasonic vibration boring dry cutting of hardened material are also summarized. The test results show that the ultrasonic vibration cutting tool boring is of very superior cutting mechanism and is a high-precision deep-hole machining of hardened materials, efficient cutting methods.

  2. Obtaining strong zirconia ceramic by hardening and tempering

    SciTech Connect

    Pliner, S.Y.; Dabizha, A.A.; Komolikov, Y.I.; Rutman, D.S.; Toropov, Y.S.

    1985-07-01

    To determine whether it is possible to strengthen ceramics by means of hardening and tempering, the authors selected a solid solution pf 3.4% of Y/sub 2/O/sub 3/ (molar fraction) in ZrO/sub 2/. The solution was synthesized by combined precipitation of the compounds from an aqueous solution of chlorides. The filtered residue of hydroxides was dried and calcined at about 900/sup 0/C. The calcined material was milled for 80 h in an iron ball mill by the wet method with a ratio of materials: balls: water of 1:2:1. The material was then purified to remove tramp iron by treatment with HC1 with an addition of hydrogen peroxide, followed by decantation with distilled water. The specimens were heated to 2250-2300/sup 0/C in a furnace with a straight-through vertical channel of diameter 20 mm, a heating element made of stabilized zirconia, and high-temperature heat insulation made of porous ceramic-concrete based on ZrO/sub 2/. The hardening of the specimens at this temperature was done at a rate ensuring practically complete preservation of the cubic phase of ZrO/sub 2/. The tempering of the hardened specimens was done by the furnace with a silit heaters at 1400/sup 0/C over different times (0-85 h).

  3. Characterization by matrix-assisted laser desorption/ionization Fourier transform ion cyclotron resonance mass spectrometry of the major photoproducts of temoporfin (m-THPC) and bacteriochlorin (m-THPBC).

    PubMed

    Angotti, M; Maunit, B; Muller, J F; Bezdetnaya, L; Guillemin, F

    2001-07-01

    The photobleaching of 5,10,15,20-tetrakis(m-hydroxyphenyl)chlorin (temoporfin, m-THPC) and 5,10,15,20-tetrakis(m-hydroxyphenyl)bacteriochlorin (bacteriochlorin, m-THPBC) was studied in ethanol-water (1 : 99, v/v) and in physiological medium (phosphate-buffered saline, PBS) with or without fetal calf serum (FCS). m-THPC solution was irradiated with the laser radiation of 650 nm, whereas m-THPBC solution underwent two consecutive irradiations at 532 and 650 nm. The photoproducts were characterized by UV-visible absorption spectrophotometry and by matrix-assisted laser desorption/ionization (MALDI) coupled with Fourier transform ion cyclotron resonance mass spectrometry (FTICRMS). Independent of the solvent used, the phototransformation of either photosensitizer yielded the formation of 5,10,15,20-tetrakis (m-hydroxyphenyl)porphyrin (m-THPP) through a major dehydrogenation process. PMID:11473406

  4. First-principles assessment of potential ultrafast laser-induced structural transition in Ni

    NASA Astrophysics Data System (ADS)

    Bévillon, E.; Colombier, J. P.; Stoian, R.

    2016-06-01

    The possibility to trigger ultrafast solid-to-solid transitions in transition metals under femtosecond laser irradiation is investigated by means of first-principles calculations. Electronic heating can drastically modify screening, charge distribution and atomic binding features, potentially determining new structural relaxation paths in the solid phase, before thermodynamic solid-to-liquid transformations set in. Consequently, we evaluate here the effect of electronic excitation on structural stability and conditions for structural transitions. Ni is chosen as a case study for the probability of a solid transition, and the stability of its FCC phase is compared to the non-standard HCP structure while accounting for the heating of the electronic subsystem. From a phonon spectra analysis, we show that the thermodynamic stability order reverses at an electronic temperature of around 104 K. Both structures exhibit a dynamic stability, indicating they present a metastability depending on the heating. However, the general hardening of phonon modes with the increase of the electronic temperature points out that no transformation will occur, as confirmed by the study of a typical FCC to HCP diffusionless transformation path, showing an increasing energy barrier. Finally, based on electronic density of states interpretation, the tendency of different metal categories to undergo or not an ultrafast laser-induced structural transition is discussed.

  5. Imaging Fourier transform spectrometer

    SciTech Connect

    Bennett, C.L.

    1993-09-13

    This invention is comprised of an imaging Fourier transform spectrometer having a Fourier transform infrared spectrometer providing a series of images to a focal plane array camera. The focal plane array camera is clocked to a multiple of zero crossing occurrences as caused by a moving mirror of the Fourier transform infrared spectrometer and as detected by a laser detector such that the frame capture rate of the focal plane array camera corresponds to a multiple of the zero crossing rate of the Fourier transform infrared spectrometer. The images are transmitted to a computer for processing such that representations of the images as viewed in the light of an arbitrary spectral ``fingerprint`` pattern can be displayed on a monitor or otherwise stored and manipulated by the computer.

  6. An extension of the Kocks-Mecking model of work hardening to include kinematic hardening and its application to solutes in ferrite

    NASA Astrophysics Data System (ADS)

    Bouaziz, O.; Barbier, D.; Embury, J. D.; Badinier, G.

    2013-01-01

    It is well known that the addition of a solute can change both work-hardening characteristics and yield stress; however, there are few available models which describe the role of a solute in relation to both the isotropic and kinematic aspects of work hardening. The current work extends the well-established approach of Kocks and Mecking to include the occurrence of cross slip and its dependence on solute content. The proposed model is compared with experimental data for the system Fe-Al by reference both to the observed work hardening in monotonic loading and the Bauschinger effect measured in reverse shear tests. The agreement between the model and the experimental data is satisfactory and suggests a new description of work hardening which includes a prediction of the ratio of isotropic and kinematic hardening for a given solute content.

  7. An Evaluation of the Corrosion and Mechanical Performance of Interstitially Surface-Hardened Stainless Steel

    NASA Astrophysics Data System (ADS)

    Jones, Jennifer L.; Koul, Michelle G.; Schubbe, Joel J.

    2014-06-01

    A surface hardening technique called "interstitial hardening" is commercially available, whereby interstitial carbon atoms are introduced into stainless steel surfaces without the formation of carbides. Surface hardening of machine elements such as impellors or fasteners would improve performance regarding cavitation and galling resistance, and has intensified interest in this process. However, there remains a need to characterize and validate the specific performance characteristics of the hardened materials. This paper describes experimental testing conducted on 316L stainless steel that has been surface hardened using available commercial techniques, using carbon as the interstitial atom. The corrosion performance of the hardened surface is assessed using electrochemical potentiodynamic testing to determine the breakdown potential in 3.5 wt.% NaCl solution to identify the most promising method. The hardness and thickness of the surface-hardened layer is characterized and compared using metallography and microhardness profiling. Corrosion fatigue and slow strain rate testing of untreated, hardened, and damaged, hardened surfaces exposed to ASTM seawater is conducted. Finally, critical galling stresses are determined and compared. Post-test examination of damage attempts to identify mechanisms of material failure and characterize how corrosion-assisted cracks initiate and grow in surface-hardened materials.

  8. Comparison of Fourier Transform Infrared Spectroscopy (FTIR) and Tunable Diode Laser Absorption Spectroscopy (TDLAS) Methods for Determining Stable Isotope Ratios of Atmospheric CO2

    NASA Astrophysics Data System (ADS)

    Ubierna Lopez, N.; Cambaliza, M. L.; Griffith, D. W.; Mount, G. H.; Cousins, A. B.

    2011-12-01

    Worldwide, biosphere-atmosphere carbon exchange and net ecosystem exchange (NEE) are determined using eddy-covariance methods. Information from isotopic CO2 measurements provides valuable constraints to partition NEE into its component fluxes. Stable isotope measurements have traditionally been constrained in frequency by the need to collect and analyze field samples in a laboratory using isotope ratio mass spectrometry (MS). New techniques based on absorption spectroscopy allow for high temporal sampling resolution in the field, but with concerns about precision and accuracy of the isotope-ratios. We tested two absorption spectroscopy systems, a Fourier transformed infrared analyzer (FTIR, Vector 22, Bruker Optics, Ettlingen, Germany) and a tunable diode laser absorption spectrometer (TDLAS, model TGA 100, Campbell Scientific, Inc. Logan, UT, USA), by comparing them with continuous-flow MS (Delta plus XP IRMS, ThermoFinnigan, Bremen, Germany). We conducted a laboratory comparison of gases mixed with various CO2 concentrations and isotopic signatures as well as field-collected samples. The mixed tanks were balanced in ultra-zero air with CO2 concentrations ranging from 353 to 553 ppm, and isotopic compositions (δ13C) between -11.7% to -39.3%. The field samples were collected at four different locations (forest, wheat field, dairy farm, and paper mill) by pumping ambient air into 44- L tanks. Gas from each sample tank was simultaneously delivered to the FTIR and TDLAS systems and subsequently analyzed with continuous-flow MS. The [CO2] determined with the TDLAS or FTIR differed by <1 ppm for CO2-tanks and <2.4 ppm for ambient air samples. The δ13C offset of the CO2 tanks between the MS and the TDLAS and FTIR were on average 0.1% and 0.3%, respectively. However, the offset in TDLAS δ13C values increased for ambient air samples to values of 0.4%, with a maximum of 0.9% for the dairy farm and paper mill samples. Ambient air samples analyzed with the FTIR were on

  9. Case studies of industrial applications of high-power diode laser in Finland

    NASA Astrophysics Data System (ADS)

    Hovikorpi, Jari; Jansson, Anssi; Salminen, Antti

    2003-06-01

    The high power diode laser is a new industrial tool. It has several advantages and disadvantages compared to the conventional industrially used CO2 and Nd:YAG laser. The most promising areas of application of diode laser have been considered to be thin sheet welding and hardening. Quite a few feasibility studies of the use of diode laser have been carried out in Finland. So far there has been some application in which diode laser is the most suitable laser. Typically, the HPDL is integrated to an industrial robot. The welding of stainless steel housing, car door lock and catalytic converters are typical examples of applications in which diode laser has technological as well as economical advantages over the conventional laser and welding techniques. The welding of these products requires good control over the heat input, short through put time and low investment. The weld cross-section of a diode laser weld is, because of conduction limited welding process, more suitable for these applications than the keyhole welding. Hardening of a large gear wheel presents also a good example of an application in which the diode laser makes it possible to economically produce structures that have not earlier been possible. Hardening requires a special form of heat delivery in order to ensure evenly hardened zone and acceptable quality. The application was performed with two high power diode lasers. The case studies of these four applications are presented and discussed in details in this paper.

  10. Effect of grain structure on phase transformation events in Inconel 718

    SciTech Connect

    Dahotre, N.B.; McCay, M.H.; McCay, T.D. ); Hubbard, C.R.; Porter, W.D.; Cavin, O.B. )

    1993-06-01

    Nickel base superalloys generally obtain their maximum strength from [gamma][prime][Ni[sub 3](Al,Ti)] and [gamma][double prime][Ni[sub 3](Al,Ti,Nb)] age hardening precipitates. During welding the [gamma][prime] precipitation is very rapid and can lead to strain age cracking, which limits weldability. Thus, the weldable superalloys are limited in their Al and Ti content and hence in their ultimate strength. One method of increasing the ultimate strength of a superalloy, while avoiding strain age cracking, is the addition of Nb. This produces Ni[sub 3]Nb([delta]), and when used in conjunction with a limited amount of [gamma][prime], results in an increase in strength without strain age cracking problems. The [gamma][double prime] does not lead to strain age cracking because its transformation kinetics are too slow for formation during ordinary welding practice. This combination of [gamma][prime] and [gamma][double prime] strengthening is incorporated into the Inconel 718 alloys. The research reported herein was undertaken to determine the time-temperature response of Inconel 718 in the as-cast, wrought and wrought-grain-grown states, using differential thermal analysis (DTA). It is essential to locate the temperature regime of each phase transformation event and to study the transformation sequence in order to tailor sound laser welding techniques for Inconel 718. In the present research, a DTA technique was employed to study both the phase transformation events and the phase transformation sequence as a function of the pre-existing condition of the alloy.

  11. Highly efficient pulsed power supply system with a two-stage LC generator and a step-up transformer for fast capillary discharge soft x-ray laser at shorter wavelength

    NASA Astrophysics Data System (ADS)

    Sakai, Yusuke; Takahashi, Shnsuke; Komatsu, Takanori; Song, Inho; Watanabe, Masato; Hotta, Eiki

    2010-01-01

    Highly efficient and compact pulsed power supply system for a capillary discharge soft x-ray laser (SXRL) has been developed. The system consists of a 2.2 μF two-stage LC inversion generator, a 2:54 step-up transformer, a 3 nF water capacitor, and a discharge section with a few tens of centimeter length capillary. Adoption of the pulsed transformer in combination with the LC inversion generator enables us to use only one gap switch in the circuit for charging the water capacitor up to about 0.5 MV. Furthermore, step-up ratio of a water capacitor voltage to a LC inversion generator initial charging voltage is about 40 with energy transfer efficiency of about 50%. It also leads to good reproducibility of a capillary discharge which is necessary for lasing a SXRL stably. For the study of the possibility of lasing a SXRL at shorter wavelength in a small laboratory scale, high-density and high-temperature plasma column suitable for the laser can be generated relatively easily with this system.

  12. Highly efficient pulsed power supply system with a two-stage LC generator and a step-up transformer for fast capillary discharge soft x-ray laser at shorter wavelength

    SciTech Connect

    Sakai, Yusuke; Takahashi, Shnsuke; Komatsu, Takanori; Song, Inho; Watanabe, Masato; Hotta, Eiki

    2010-01-15

    Highly efficient and compact pulsed power supply system for a capillary discharge soft x-ray laser (SXRL) has been developed. The system consists of a 2.2 {mu}F two-stage LC inversion generator, a 2:54 step-up transformer, a 3 nF water capacitor, and a discharge section with a few tens of centimeter length capillary. Adoption of the pulsed transformer in combination with the LC inversion generator enables us to use only one gap switch in the circuit for charging the water capacitor up to about 0.5 MV. Furthermore, step-up ratio of a water capacitor voltage to a LC inversion generator initial charging voltage is about 40 with energy transfer efficiency of about 50%. It also leads to good reproducibility of a capillary discharge which is necessary for lasing a SXRL stably. For the study of the possibility of lasing a SXRL at shorter wavelength in a small laboratory scale, high-density and high-temperature plasma column suitable for the laser can be generated relatively easily with this system.

  13. On the Effect of Manganese on Grain Size Stability and Hardenability in Ultrafine-Grained Ferrite/Martensite Dual-Phase Steels

    NASA Astrophysics Data System (ADS)

    Calcagnotto, Marion; Ponge, Dirk; Raabe, Dierk

    2012-01-01

    Two plain carbon steels with varying manganese content (0.87 wt pct and 1.63 wt pct) were refined to approximately 1 μm by large strain warm deformation and subsequently subjected to intercritical annealing to produce an ultrafine grained ferrite/martensite dual-phase steel. The influence of the Mn content on microstructure evolution is studied by scanning electron microscopy (SEM). The Mn distribution in ferrite and martensite is analyzed by high-resolution electron backscatter diffraction (EBSD) combined with energy dispersive X-ray spectroscopy (EDX). The experimental findings are supported by the calculated phase diagrams, equilibrium phase compositions, and the estimated diffusion distances using Thermo-Calc (Thermo-Calc Software, McMurray, PA) and Dictra (Thermo-Calc Software). Mn substantially enhances the grain size stability during intercritical annealing and the ability of austenite to undergo martensitic phase transformation. The first observation is explained in terms of the alteration of the phase transformation temperatures and the grain boundary mobility, while the second is a result of the Mn enrichment in cementite during large strain warm deformation, which is inherited by the newly formed austenite and increases its hardenability. The latter is the main reason why the ultrafine-grained material exhibits a hardenability that is comparable with the hardenability of the coarse-grained reference material.

  14. Method for increasing the rate of compressive strength gain in hardenable mixtures containing fly ash

    DOEpatents

    Liskowitz, John W.; Wecharatana, Methi; Jaturapitakkul, Chai; Cerkanowicz, deceased, Anthony E.

    1997-01-01

    The present invention relates to concrete, mortar and other hardenable mixtures comprising cement and fly ash for use in construction. The invention provides a method for increasing the rate of strength gain of a hardenable mixture containing fly ash by exposing the fly ash to an aqueous slurry of calcium oxide (lime) prior to its incorporation into the hardenable mixture. The invention further relates to such hardenable mixtures, e.g., concrete and mortar, that contain fly ash pre-reacted with calcium oxide. In particular, the fly ash is added to a slurry of calcium oxide in water, prior to incorporating the fly ash in a hardenable mixture. The hardenable mixture may be concrete or mortar. In a specific embodiment, mortar containing fly ash treated by exposure to an aqueous lime slurry are prepared and tested for compressive strength at early time points.

  15. Method for increasing the rate of compressive strength gain in hardenable mixtures containing fly ash

    DOEpatents

    Liskowitz, J.W.; Wecharatana, M.; Jaturapitakkul, C.; Cerkanowicz, A.E.

    1997-10-28

    The present invention relates to concrete, mortar and other hardenable mixtures comprising cement and fly ash for use in construction. The invention provides a method for increasing the rate of strength gain of a hardenable mixture containing fly ash by exposing the fly ash to an aqueous slurry of calcium oxide (lime) prior to its incorporation into the hardenable mixture. The invention further relates to such hardenable mixtures, e.g., concrete and mortar, that contain fly ash pre-reacted with calcium oxide. In particular, the fly ash is added to a slurry of calcium oxide in water, prior to incorporating the fly ash in a hardenable mixture. The hardenable mixture may be concrete or mortar. In a specific embodiment, mortar containing fly ash treated by exposure to an aqueous lime slurry are prepared and tested for compressive strength at early time points. 2 figs.

  16. Fatigue resistance of titanium alloy VT3-1 connection with surface work-hardening

    SciTech Connect

    Stepnov, M.N.; Agamirov, L.V.; Giatsintov, E.V.; Gus'kova, L.N.; Veitsman, M.G.

    1985-11-01

    The authors describe how surface work-hardening increases the endurance limit of smooth specimens of titanium alloy VT3-1 cut from bars by 25-30%. The range of the efficiency of strain-hardening by vibrational treatment and burnishing is 3-7%, the exact percentage depending on processing factors in each form of work-hardening. Work-hardening reduces scatter of fatigue characteristics, which enhances the effectiveness of the resulting strain-hardening with a decrease in the probability of fracture. Surface strain-hardening is recommended for alloy VT3-1, since it increases resistance to fatigue and reduces scatter of fatigue characteristics used in design.

  17. Case depth verification of hardened samples with Barkhausen noise sweeps

    SciTech Connect

    Santa-aho, Suvi; Vippola, Minnamari; Lepistö, Toivo; Hakanen, Merja; Sorsa, Aki; Leiviskä, Kauko

    2014-02-18

    An interesting topic of recent Barkhausen noise (BN) method studies is the application of the method to case depth evaluation of hardened components. The utilization of BN method for this purpose is based on the difference in the magnetic properties between the hardened case and the soft core. Thus, the detection of case depth with BN can be achieved. The measurements typically have been carried out by using low magnetizing frequencies which have deeper penetration to the ferromagnetic samples than the conventional BN measurement. However, the penetration depth is limited due to eddy current damping of the signal. We introduce here a newly found sweep measurement concept for the case depth evaluation. In this study sweep measurements were carried out with various magnetizing frequencies and magnetizing voltages to detect the effect of different frequency and voltage and their correspondence to the actual case depth values verified from destructive characterization. Also a BN measurement device that has an implemented sweep analysis option was utilised. The samples were either induction or case-hardened samples and sample geometry contained both rod samples and gear axle samples with different case depth values. Samples were also further characterized with Xray diffraction to study the residual stress state of the surface. The detailed data processing revealed that also other calculated features than the maximum slope division of the 1st derivative of the BN signal could hold the information about the case depth value of the samples. The sweep method was able to arrange the axles into correct order according to the case depth value even though the axles were used.

  18. Case depth verification of hardened samples with Barkhausen noise sweeps

    NASA Astrophysics Data System (ADS)

    Santa-aho, Suvi; Hakanen, Merja; Sorsa, Aki; Vippola, Minnamari; Leiviskä, Kauko; Lepistö, Toivo

    2014-02-01

    An interesting topic of recent Barkhausen noise (BN) method studies is the application of the method to case depth evaluation of hardened components. The utilization of BN method for this purpose is based on the difference in the magnetic properties between the hardened case and the soft core. Thus, the detection of case depth with BN can be achieved. The measurements typically have been carried out by using low magnetizing frequencies which have deeper penetration to the ferromagnetic samples than the conventional BN measurement. However, the penetration depth is limited due to eddy current damping of the signal. We introduce here a newly found sweep measurement concept for the case depth evaluation. In this study sweep measurements were carried out with various magnetizing frequencies and magnetizing voltages to detect the effect of different frequency and voltage and their correspondence to the actual case depth values verified from destructive characterization. Also a BN measurement device that has an implemented sweep analysis option was utilised. The samples were either induction or case-hardened samples and sample geometry contained both rod samples and gear axle samples with different case depth values. Samples were also further characterized with Xray diffraction to study the residual stress state of the surface. The detailed data processing revealed that also other calculated features than the maximum slope division of the 1st derivative of the BN signal could hold the information about the case depth value of the samples. The sweep method was able to arrange the axles into correct order according to the case depth value even though the axles were used.

  19. Radiation-Hardened Software for Space Flight Science Applications

    NASA Astrophysics Data System (ADS)

    Mehlitz, P. C.; Penix, J. J.; Markosian, L. Z.

    2005-12-01

    Hardware faults caused by radiation-induced Single Event Effects (SEEs) are a serious issue in space flight, especially affecting scientific missions in earth orbits crossing the poles or the South Atlantic Anomaly. Traditionally, SEEs are treated as a hardware problem, for example mitigated by radiation-hardened processors and shielding. Rad-hardened processors are expensive, exhibit a decade performance gap compared to COTS technology, have a larger form factor and require more power. Shielding is ineffective for high energy particles and increases launch weight. Hardware approaches cannot dynamically adapt protection levels for different radiation scenarios depending on solar activity and flight phase. Future hardware will exacerbate the problem due to higher chip densities and lower power levels. An alternative approach is to use software to mitigate SEEs. This "Radiation Hardened Software" (RHS) approach has two components: (1) RHS library and application design guidelines To increase robustness, we combine SEE countermeasures in three areas: prevention and detection; recovery; and reconfiguration. Prevention and detection includes an application- and heap-aware memory scanner, and dynamically adapted software Error Correction Codes to handle cache and multi-bit errors. Recovery mechanisms include exception firewalls and transaction-based software design patterns, to minimize data loss. Reconfiguration includes a heap manager to avoid damaged memory areas. (2) Software-based SEE Simulation Probabilistic effects require extensive simulation, with test environments that do not require original flight hardware and can simulate various SEE profiles. We use processor emulation software, interfaced to a debugger, to analyze SEE propagation and optimize RHS mechanisms. The simulator runs unmodified binary flight code, enables injecting randomized transient and permanent memory errors, providing execution traces and precise failure reproduction. The goal of RHS is to

  20. Ductility and work hardening in nano-sized metallic glasses

    SciTech Connect

    Chen, D. Z.; Gu, X. W.; An, Q.; Goddard, W. A.; Greer, J. R.

    2015-02-09

    In-situ nano-tensile experiments on 70 nm-diameter free-standing electroplated NiP metallic glass nanostructures reveal tensile true strains of ∼18%, an amount comparable to compositionally identical 100 nm-diameter focused ion beam samples and ∼3 times greater than 100 nm-diameter electroplated samples. Simultaneous in-situ observations and stress-strain data during post-elastic deformation reveal necking and work hardening, features uncharacteristic for metallic glasses. The evolution of free volume within molecular dynamics-simulated samples suggests a free surface-mediated relaxation mechanism in nano-sized metallic glasses.

  1. Substorm effects in auroral spectra. [electron spectrum hardening

    NASA Technical Reports Server (NTRS)

    Eather, R. H.; Mende, S. B.

    1973-01-01

    A substorm time parameter is defined and used to order a large body of photometric data obtained on aircraft expeditions at high latitudes. The statistical analysis demonstrates hardening of the electron spectrum at the time of substorm, and it is consistent with the accepted picture of poleward expansion of aurora at the time of substorm and curvature drift of substorm-injected electrons. These features are not evident from a similar analysis in terms of magnetic time. We conclude that the substorm time concept is a useful ordering parameter for auroral data.

  2. Hardening communication ports for survival in electrical overstress environments

    NASA Technical Reports Server (NTRS)

    Clark, O. Melville

    1991-01-01

    Greater attention is being focused on the protection of data I/O ports since both experience and lab tests have shown that components at these locations are extremely vulnerable to electrical overstress (EOS) in the form of transient voltages. Lightning and electrostatic discharge (ESD) are the major contributors to these failures; however, these losses can be prevented. Hardening against transient voltages at both the board level and system level has a proven record of improving reliability by orders of magnitude. The EOS threats, typical failure modes, and transient voltage mitigation techniques are reviewed. Case histories are also reviewed.

  3. Action Of Cement Hardening On Artificial Hip Joint Components

    NASA Astrophysics Data System (ADS)

    Roder, U.; Niess, N.; Plitz, W.

    1981-05-01

    Artificial acetabular cups loose their original shape and undergo deformations during implantation, caused by the polymerization shrinkage of the bone cement. In laboratory experiments, two acetabula of different material - both common in clinical use - were studied by holographic real-time interferometry during cement hardening. This method picks up characteristic features in the transient behaviour of the form changes. It is shown, that temperature, porosity and shrinkage of the cement has a large influence on the form of a polyethylene acetabulum, whereas there is only little effect on an acetabulum, made of alumina ceramic.

  4. Surface hardening of cutting elements agricultural machinery vibro arc plasma

    NASA Astrophysics Data System (ADS)

    Sharifullin, S. N.; Adigamov, N. R.; Adigamov, N. N.; Solovev, R. Y.; Arakcheeva, K. S.

    2016-01-01

    At present, the state technical policy aimed at the modernization of worn equipment, including agriculture, based on the use of high-performance technology called nanotechnology. By upgrading worn-out equipment meant restoring it with the achievement of the above parameters passport. The existing traditional technologies are not suitable for the repair of worn-out equipment modernization. This is especially true of imported equipment. Out here alone - is the use of high-performance technologies. In this paper, we consider the use of vibro arc plasma for surface hardening of cutting elements of agricultural machinery.

  5. Active radiation hardening technology for fiber-optic source

    NASA Astrophysics Data System (ADS)

    Yang, Yuanhong; Suo, Xinxin; Yang, Mingwei

    2013-09-01

    We demonstrated an active radiation hardening technology for fiber optic source developed for high performance fiber optic gyroscope. The radiation characteristic of erbium-doped fiber was studied experimentally. The radiation induced attenuation (RIA) at 980nm pump light was identified to be the main reason for the degradation and there was photo-bleaching effect in EDF too. A variable parameters control technology was proposed and taken to keep the 980nm and 1550nm light energy stable and high stability and radiation-resistance fiber source with gauss profile spectrum was realized .The source can stand against more than 50 krad (Si) total radiation dose.

  6. Development of a Pressure-Dependent Constitutive Model with Combined Multilinear Kinematic and Isotropic Hardening

    NASA Technical Reports Server (NTRS)

    Allen Phillip A.; Wilson, Christopher D.

    2003-01-01

    The development of a pressure-dependent constitutive model with combined multilinear kinematic and isotropic hardening is presented. The constitutive model is developed using the ABAQUS user material subroutine (UMAT). First the pressure-dependent plasticity model is derived. Following this, the combined bilinear and combined multilinear hardening equations are developed for von Mises plasticity theory. The hardening rule equations are then modified to include pressure dependency. The method for implementing the new constitutive model into ABAQUS is given.

  7. Hardening mechanisms in a dynamic strain aging alloy, Hastelloy X, during isothermal and thermomechanical cyclic deformation

    NASA Technical Reports Server (NTRS)

    Miner, R. V.; Castelli, M. G.

    1992-01-01

    The relative contributions of the hardening mechanisms in Hastelloy X during cyclic deformation were investigated by conducting isothermal cyclic deformation tests within a total strain range of +/-0.3 pct and at several temperatures and strain rates, and thermomechanical tests within several different temperature limits. The results of the TEM examinations and special constant structure tests showed that the precipitation on dislocations of Cr23C6 contributed to hardening, but only after sufficient time above 500 C. Solute drag alone produced very considerable cyclic hardening. Heat dislocation densities, peaking around 10 exp 11 per sq cm, were found to develop at temperatures producing the greatest cyclic hardening.

  8. A radiation-hardened, computer for satellite applications

    SciTech Connect

    Gaona, J.I. Jr.

    1996-08-01

    This paper describes high reliability radiation hardened computers built by Sandia for application aboard DOE satellite programs requiring 32 bit processing. The computers highlight a radiation hardened (10 kGy(Si)) R3000 executing up to 10 million reduced instruction set instructions (RISC) per second (MIPS), a dual purpose module control bus used for real-time default and power management which allows for extended mission operation on as little as 1.2 watts, and a local area network capable of 480 Mbits/s. The central processing unit (CPU) is the NASA Goddard R3000 nicknamed the ``Mongoose or Mongoose 1``. The Sandia Satellite Computer (SSC) uses Rational`s Ada compiler, debugger, operating system kernel, and enhanced floating point emulation library targeted at the Mongoose. The SSC gives Sandia the capability of processing complex types of spacecraft attitude determination and control algorithms and of modifying programmed control laws via ground command. And in general, SSC offers end users the ability to process data onboard the spacecraft that would normally have been sent to the ground which allows reconsideration of traditional space-grounded partitioning options.

  9. DISCREPANT HARDENING OBSERVED IN COSMIC-RAY ELEMENTAL SPECTRA

    SciTech Connect

    Ahn, H. S.; Ganel, O.; Han, J. H.; Kim, K. C.; Lee, M. H.; Lutz, L.; Malinin, A.; Allison, P.; Beatty, J. J.; Bagliesi, M. G.; Bigongiari, G.; Maestro, P.; Marrocchesi, P. S.; Childers, J. T.; DuVernois, M. A.; Conklin, N. B.; Coutu, S.; Mognet, S. I.; Jeon, J. A.; Minnick, S.

    2010-05-01

    The balloon-borne Cosmic Ray Energetics And Mass experiment launched five times from Antarctica has achieved a cumulative flight duration of about 156 days above 99.5% of the atmosphere. The instrument is configured with complementary and redundant particle detectors designed to extend direct measurements of cosmic-ray composition to the highest energies practical with balloon flights. All elements from protons to iron nuclei are separated with excellent charge resolution. Here, we report results from the first two flights of {approx}70 days, which indicate hardening of the elemental spectra above {approx}200 GeV/nucleon and a spectral difference between the two most abundant species, protons and helium nuclei. These results challenge the view that cosmic-ray spectra are simple power laws below the so-called knee at {approx}10{sup 15} eV. This discrepant hardening may result from a relatively nearby source, or it could represent spectral concavity caused by interactions of cosmic rays with the accelerating shock. Other possible explanations should also be investigated.

  10. Dislocation Starvation and Exhaustion Hardening in Mo-alloy Nanofibers

    SciTech Connect

    Chisholm, Claire; Bei, Hongbin; Lowry, M. B.; Oh, Jason; Asif, S.A. Syed; Warren, O.; Shan, Zhiwei; George, Easo P; Minor, Andrew

    2012-01-01

    The evolution of defects in Mo alloy nanofibers with initial dislocation densities ranging from 0 to 1.6 1014 m2 were studied using an in situ push-to-pull device in conjunction with a nanoindenter in a transmission electron microscope. Digital image correlation was used to determine stress and strain in local areas of deformation. When they had no initial dislocations the Mo alloy nanofibers suffered sudden catastrophic elongation following elastic deformation to ultrahigh stresses. At the other extreme fibers with a high dislocation density underwent sustained homogeneous deformation after yielding at much lower stresses. Between these two extremes nanofibers with intermediate dislocation densities demonstrated a clear exhaustion hardening behavior, where the progressive exhaustion of dislocations and dislocation sources increases the stress required to drive plasticity. This is consistent with the idea that mechanical size effects ( smaller is stronger ) are due to the fact that nanostructures usually have fewer defects that can operate at lower stresses. By monitoring the evolution of stress locally we find that exhaustion hardening causes the stress in the nanofibers to surpass the critical stress predicted for self-multiplication, supporting a plasticity mechanism that has been hypothesized to account for the rapid strain softening observed in nanoscale bcc materials at high stresses.

  11. Folding and faulting of strain-hardening sedimentary rocks

    USGS Publications Warehouse

    Johnson, A.M.

    1980-01-01

    The question of whether single- or multi-layers of sedimentary rocks will fault or fold when subjected to layer-parallel shortening is investigated by means of the theory of elastic-plastic, strain-hardening materials, which should closely describe the properties of sedimentary rocks at high levels in the Earth's crust. The most attractive feature of the theory is that folding and faulting, intimately related in nature, are different responses of the same idealized material to different conditions. When single-layers of sedimentary rock behave much as strain-hardening materials they are unlikely to fold, rather they tend to fault, because contrasts in elasticity and strength properties of sedimentary rocks are low. Amplifications of folds in such materials are negligible whether contacts between layer and media are bonded or free to slip for single layers of dolomite, limestone, sandstone, or siltstone in media of shale. Multilayers of these same rocks fault rather than fold if contacts are bonded, but they fold readily if contacts between layers are frictionless, or have low yield strengths, for example due to high pore-water pressure. Faults may accompany the folds, occurring where compression is increased in cores of folds. Where there is predominant reverse faulting in sedimentary sequences, there probably were few structural units. ?? 1980.

  12. Analysis on sheet cyclic plastic deformation using mixed hardening model

    NASA Astrophysics Data System (ADS)

    Li, Qun; Jin, Miao; Yuxin, Zhu

    2013-05-01

    Treating the cyclic deformation problem of sheet flowing through drawbead as the object of the research, using HILL anisotropy yield criterion and mixed hardening model, the cyclic plastic deformation mechanism of sheet was studied, the deformation characteristics of sheet subjected to cyclic loads were revealed, and the influence of Bauschinger effect on stress-strain circulating relationship and the influence of bending neutral layer migration on the stress of sheet's intermediate integral point were analyzed as well. The effectiveness of the model was verified by experiments. The results of analysis were showed that the stress values influenced by Bauschinger effect were different at the yield point of reverse loading and the point of unloading during the cyclic deformation. The stress rate at the yield point of reverse loading and the point of unloading in different loading branches was also different. The stress-strain circulating relationship in different loading branches can be approximately treated as bilinear. The tangent modulus of each loading branch showed a significant downward trend as the times of the reverse loading increased. The tangent modulus calculated by the mixed hardening model after the second loading branch reduced to less than 21% of the first loading tangent modulus. Effected by the neutral layer migration, the stress-strain curve of integral point of sheet's intermediate layer showed alternating transition phenomenon of the tensile stress and compressive stress.

  13. Effects of residual stress on irradiation hardening in stainless steels

    NASA Astrophysics Data System (ADS)

    Okubo, N.; Miwa, Y.; Kondo, K.; Kaji, Y.

    2009-04-01

    Effects of residual stress on irradiation hardening were studied in advance for predicting irradiation assisted stress corrosion cracking. The specimens of SUS316 and SUS316L with several % plastic strains, which correspond to weld residual stress, were prepared by bending and keeping deformation under irradiation. Ion irradiations of 12 MeV Ni 3+ were performed at 330, 400 and 550 oC to 45 dpa. No bended specimen was simultaneously irradiated with the bended specimen. The residual stress was estimated by X-ray residual stress measurements before and after the irradiation. The micro-hardness was measured by using nanoindenter. The residual stress did not relax even for the case of the higher temperature aging at 500 oC for the same time of irradiation. The residual stress after ion irradiation up to high dpa, however, relaxed at these experimental temperatures. The irradiation hardening of stressed specimen was obviously lower than that of un-stressed one in case of SUS316L irradiated at 300 oC to 12 dpa.

  14. A high-resolution scanning microprobe matrix-assisted laser desorption/ionization ion source for imaging analysis on an ion trap/Fourier transform ion cyclotron resonance mass spectrometer.

    PubMed

    Koestler, Martin; Kirsch, Dieter; Hester, Alfons; Leisner, Arne; Guenther, Sabine; Spengler, Bernhard

    2008-10-01

    A new scanning microprobe matrix-assisted laser desorption/ionization (SMALDI) ion source for high spatial resolution has been developed for linear ion trap and Fourier transform ion cyclotron resonance mass spectrometry (FT-ICR-MS). The source is fully compatible with commercial ion trap flanges (such as the LTQ series, Thermo Fisher Scientific). The source is designed for atmospheric pressure (AP) operation but is also suitable for mid-pressure operation. The AP mode is especially useful for investigating volatile compounds. The source can be interchanged with other ion sources within a minute when operated in the AP mode. Combining high-lateral resolution MALDI imaging with high mass resolution and high mass accuracy mass spectrometry, available in the FT-ICR mode, provides a new quality of analytical information, e.g. from biological samples. First results obtained with the new ion source demonstrate a maximum lateral resolution of 0.6 by 0.5 microm. Depending on the limit of detection of the chosen mass analyzer, however, the size of the focus had to be enlarged to a diameter of up to 8 microm in the FT-ICR mode, in order to create enough ions for detection. Mass spectra acquired for analytical imaging were obtained from single laser pulses per pixel in all the experiments. This mode allows us to investigate biological thin sections with desorption focus diameters in the micrometer range, known to cause complete evaporation of material under the laser focus with a very limited number of laser pulses. As a first example, peptide samples deposited in microstructures were investigated with the new setup. A high quality and validity of the acquired images were obtained in the ion trap mode due to the low limit of detection. High mass resolution and accuracy but poorer image quality were obtained in the ICR mode due to the lower detection sensitivity of the ICR detector. PMID:18819119

  15. Continuous Hardening During Isothermal Aging at 723 K (450 °C) of a Precipitation Hardening Stainless Steel

    NASA Astrophysics Data System (ADS)

    Celada-Casero, Carola; Chao, Jesús; Urones-Garrote, Esteban; San Martin, David

    2016-06-01

    The isothermal aging behavior of a cold-rolled precipitation hardening stainless steel has been studied at 723 K (450 °C) for holding times up to 72 hours. The precipitation hardening has been investigated using microhardness Vickers (Hv), thermoelectric power (TEP) measurements, and tensile testing. Microhardness compared to TEP measurements is more sensitive to detect the initial stages of aging. Two precipitation regimes have been observed: the first one related to the formation of Cu-clusters for aging times below 1 hour and a second one associated with formation of Ni-rich precipitates. The results show that the material exhibits an outstanding continuous age strengthening response over the aging time investigated, reaching a hardness of 710 ± 4 HV1 and an ultimate tensile strength (σ UTS) of 2.65 ± 0.02 GPa after 72 hours. Engineering stress-plastic strain curves reveal that the strength increases and the ductility decreases as the aging time increases. However, after prolonged holding times (24-72 hours) and, although small, a rise in both the strength and the total elongation is observed. The precipitation kinetics can be well predicted over the entire range of aging times by the Johnson-Mehl-Avrami-Kolmogorov (JMAK) equation. Finally, a reliable linear hardness-yield strength correlation has been found, which enables a rapid evaluation of the strength from bulk hardness measurements.

  16. A Hardened CARS System Utilized for Temperature Measurements in a Supersonic Combustor

    NASA Technical Reports Server (NTRS)

    Antcliff, Richard R.; Smith, Michael W.; Jarret, Olin, Jr.; Northam, G. Burton; Cutler, Andrew D.; Taylor, David J.

    1990-01-01

    A coherent anti-Stokes Raman scattering (CARS) system has been hardened for use in a NASA Langley supersonic combustion test cell. The system can obtain temperature cross sections of the flow at three locations. The system is environmentally protected and remotely operated. Measurements were made in a scram-jet combustor model consisting of a rear- ward-facing step, followed by an expansion duct. The duct is nominally 4 feet in length. The free stream conditions were Mach 2, with static pressure which ranged from 0.8 to 1.9 atm, and a static temperature of approximately 800K. Three vertical slots were machined into each side of the duct to allow optical access. The CARS system utilized a planar BOXCARS beam arrangement. This arrangement allowed the laser beams to pass through the vertical slots in the tunnel. Translation stages were utilized to move the focussing volume within the tunnel. These stages allowed complete cross sections to be obtained at each slot location. A fiber optic carried the signal to a remotely located monochrometer and reticon detector.Data for two different flow conditions were taken at each of the three slot locations. These two conditions provided a comparison between reacting and non-reacting mixing of injected hydrogen fuel with the combustion heated supersonic stream.

  17. Experimental study of self-compacted concrete in hardened state

    NASA Astrophysics Data System (ADS)

    Parra Costa, Carlos Jose

    The main aim of this work is to investigate the hardened behaviour of Self-Compacting Concrete (SCC). Self compacting Concrete is a special concrete that can flow in its gravity and fill in the formwork alone to its self-weight, passing through the bars and congested sections without the need of any internal or external vibration, while maintaining adequate homogeneity. SCC avoids most of the materials defects due to bleeding or segregation. With regard to its composition, SCC consists of the same components as traditional vibrated concrete (TC), but in different proportions. Thus, the high amount of superplasticizer and high powder content have to taken into account. The high workability of SCC does not allow to use traditional methods for measuring the fresh state properties, so new tests has developed (slump-flow, V-funnel, L-box, and others). The properties of the hardened SCC, which depend on the mix design, should be different from traditional concrete. In order to study the possible modifications of SCC hardened state properties, a review of the bibliography was done. The state of art was focused on the mechanical behaviour (compressive strength, tension strength and elastic modulus), on bond strength of reinforcement steel, and on material durability. The experimental program consisted in the production of two types of concretes: Self-Compacting Concrete and Traditional Concrete. Four different dosages was made with three different water/cement ratio and two strength types of Portland cement, in order to cover the ordinary strength used in construction. Based on this study it can be concluded that compressive strength of SCC and TC are similar (the differences are lesser than 10%), whereas the tensile strength of TC are up to 18% higher. The values of elastic modulus of both concrete are similar. On the other hand, in the ultimate state the bond strength of SCC and TC is similar, although SCC shows higher bond stiffness in the serviceability state (initial

  18. Some new results on irradiation characteristics of synthetic quartz crystals and their application to radiation hardening

    NASA Technical Reports Server (NTRS)

    Bahadur, H.; Parshad, R.

    1983-01-01

    The paper reports some new results on irradiation characteristics of synthetic quartz crystals and their application to radiation hardening. The present results show how the frequency shift in quartz crystals can be influenced by heat processing prior to irradiation and how this procedure can lead to radiation hardening for obtaining precise frequencies and time intervals from quartz oscillators in space.

  19. Strain hardening during mechanical twining and dislocation channeling in irradiated 316 stainless steels

    SciTech Connect

    Byun, Thak Sang; Hashimoto, Naoyuki

    2007-01-01

    Localized deformation mechanisms and strain-hardening behaviors in irradiated 316 and 316LN stainless steels were investigated, and a theoretical model was proposed to explain the linear strain-hardening behavior during the localized deformation. After low temperature irradiation to significant doses the deformation microstructure changed from dislocation tangles to channels or to mechanical twins. It was also observed that irradiation hardening straightened gliding dislocations and increased the tendency for forming pileups. Regardless of these microstructural changes, the strain-hardening behavior was relatively insensitive to the irradiation. This dose-independent strain-hardening rate resulted in dose independence of the true stress parameters such as the plastic instability stress and true fracture stress. In the proposed model, the long-range back stress was formulated as a function of the number of pileup dislocations per slip band and the number of slip bands in a grain. The calculation results confirmed the experimental observation that strain-hardening rate was insensitive to the change in deformation mechanism because the long-range back stress hardening became as high as the hardening by tangled dislocations.

  20. Consistency condition for isotropic-kinematic hardening of anisotropic yield functions

    NASA Astrophysics Data System (ADS)

    Chung, Kwansoo

    2013-05-01

    For the combined type isotropic-kinematic hardening law to account for the Bauschinger, transient and permanent softening behaviors observed in reverse loading, formulations have been initially developed for isotropic yield functions, mainly based on the von Mises criterion, and then later extended for anisotropic yield functions. Among the efforts to introduce anisotropic yield functions to the combined type hardening formulation, however, some inconsistency has been encountered in manipulating the kinematic hardening law, especially for the nonlinear type law, even though their von Mises yield function versions have been consistent. Therefore, theoretical clarification and clearance of such inconsistency were attempted in this work by imposing the following (consistency) condition: the combined type hardening law is expected to behave the same as the full isotropic hardening for monotonously proportional loading, regardless of (anisotropic) yield functions coupled with the combined type hardening law. An example to account for the anisotropic hardening of an anisotropic yield function utilizing the combined type hardening law, but for which the consistency condition was partially released, was also demonstrated.

  1. Universal elastic-hardening-driven mechanical instability in α-quartz and quartz homeotypes under pressure.

    PubMed

    Dong, Juncai; Zhu, Hailiang; Chen, Dongliang

    2015-01-01

    As a fundamental property of pressure-induced amorphization (PIA) in ice and ice-like materials (notably α-quartz), the occurrence of mechanical instability can be related to violation of Born criteria for elasticity. The most outstanding elastic feature of α-quartz before PIA has been experimentally reported to be the linear softening of shear modulus C44, which was proposed to trigger the transition through Born criteria B3. However, by using density-functional theory, we surprisingly found that both C44 and C66 in α-quartz exhibit strong nonlinearity under compression and the Born criteria B3 vanishes dominated by stiffening of C14, instead of by decreasing of C44. Further studies of archetypal quartz homeotypes (GeO2 and AlPO4) repeatedly reproduced the same elastic-hardening-driven mechanical instability, suggesting a universal feature of this family of crystals and challenging the long-standing idea that negative pressure derivatives of individual elastic moduli can be interpreted as the precursor effect to an intrinsic structural instability preceding PIA. The implications of this elastic anomaly in relation to the dispersive softening of the lowest acoustic branch and the possible transformation mechanism were also discussed. PMID:26099720

  2. Universal elastic-hardening-driven mechanical instability in α-quartz and quartz homeotypes under pressure

    PubMed Central

    Dong, Juncai; Zhu, Hailiang; Chen, Dongliang

    2015-01-01

    As a fundamental property of pressure-induced amorphization (PIA) in ice and ice-like materials (notably α-quartz), the occurrence of mechanical instability can be related to violation of Born criteria for elasticity. The most outstanding elastic feature of α-quartz before PIA has been experimentally reported to be the linear softening of shear modulus C44, which was proposed to trigger the transition through Born criteria B3. However, by using density-functional theory, we surprisingly found that both C44 and C66 in α-quartz exhibit strong nonlinearity under compression and the Born criteria B3 vanishes dominated by stiffening of C14, instead of by decreasing of C44. Further studies of archetypal quartz homeotypes (GeO2 and AlPO4) repeatedly reproduced the same elastic-hardening-driven mechanical instability, suggesting a universal feature of this family of crystals and challenging the long-standing idea that negative pressure derivatives of individual elastic moduli can be interpreted as the precursor effect to an intrinsic structural instability preceding PIA. The implications of this elastic anomaly in relation to the dispersive softening of the lowest acoustic branch and the possible transformation mechanism were also discussed. PMID:26099720

  3. New distortional hardening model capable of predicting eight ears for textured aluminum sheet

    SciTech Connect

    Yoon, J. H.; Cazacu, O.; Yoon, J. W.; Dick, R. E.

    2011-05-04

    The effects of the anisotropy evolution and of the directionality in hardening on the predictions of the earing profile of a strongly textured aluminum alloy are investigated using a new distortional hardening model that incorporates multiple hardening curves corresponding to uniaxial tension along several orientations with respect to the rolling direction, and to biaxial tension. Yielding is described using a form of CPB06ex2 yield function (Plunkett et al. (2008)) which is tailored for metals with no tension-compression asymmetry. It is shown that even if directional hardening and its evolution are neglected, this yield function predicts a cup with eight ears as was observed experimentally. However, directional hardening can be of considerable importance for improved accuracy in prediction of the non-uniformity of the cup height profile.

  4. Evaluation of Springback for DP980 S Rail Using Anisotropic Hardening Models

    NASA Astrophysics Data System (ADS)

    Choi, Jisik; Lee, Jinwoo; Bae, Gihyun; Barlat, Frederic; Lee, Myoung-Gyu

    2016-07-01

    The effect of anisotropic hardening models on springback of an S-rail part was investigated. Two advanced constitutive models based on distortional and kinematic hardening, which captured the Bauschinger effect, transient hardening, and permanent softening during strain path change, were implemented in a finite element (FE) code. In-plane compression-tension tests were performed to identify the model parameters. The springback of the S-rail after forming a 980 MPa dual-phase steel sheet sample was measured and analyzed using different hardening models. The comparison between experimental and FE results demonstrated that the advanced anisotropic hardening models, which are particularly suitable for non-proportional loading, significantly improved the springback prediction capability of an advanced high strength steel.

  5. A radiation-hardened 16/32-bit microprocessor

    SciTech Connect

    Hass, K.J.; Treece, R.K.; Giddings, A.E. )

    1989-12-01

    This paper reports on the development of single chip radiation-hardened 16/32-bit microprocessor. This device, the SA3300, is an emulation of National Semiconductor's NS32C016. The SA3300 is designed to withstand high levels of ionizing radiation and is resistant to single event upset (SEU) caused by heavy ions. New techniques were used to improve immunity to SEU effects in combinational logic. The authors' testing has demonstrated that the SA3300 is functional after a total gamma dose of 5 Mrad(Si). The device does not latch up from SEU, and parts without SEU resistors have an SEU linear energy transfer (LET) upset threshold greater than 28 MeV/mg/cm{sup 2}.

  6. Method of forming a hardened surface on a substrate

    DOEpatents

    Branagan, Daniel J.

    2010-08-31

    The invention includes a method of producing a hard metallic material by forming a mixture containing at least 55% iron and at least one of B, C, Si and P. The mixture is formed into an alloy and cooled to form a metallic material having a hardness of greater than about 9.2 GPa. The invention includes a method of forming a wire by combining a metal strip and a powder. The metal strip and the powder are rolled to form a wire containing at least 55% iron and from two to seven additional elements including at least one of C, Si and B. The invention also includes a method of forming a hardened surface on a substrate by processing a solid mass to form a powder, applying the powder to a surface to form a layer containing metallic glass, and converting the glass to a crystalline material having a nanocrystalline grain size.

  7. Hydrogen effects on the age hardening behavior of 2024 aluminum

    NASA Technical Reports Server (NTRS)

    Wagner, J. A.; Louthan, M. R., Jr.; Sisson, R. D., Jr.

    1986-01-01

    It has been found that the fatigue crack growth rate in aluminum alloys increases significantly in the presence of moisture. This phenomenon along with a moisture effect observed in another context has been attributed to 'embrittlement' of the aluminum by absorbed hydrogen generated by the reaction of moisture with freshly exposed aluminum. A description is given of a number of age hardening experiments involving 2024 aluminum. These experiments show that a mechanism related to the segregation of absorbed hydrogen to the coherent theta-double-prime interfaces may account for the observed reduction in fatigue life. It is pointed out that this segregation promotes a loss of coherency in the hydrogen rich region at a fatigue crack tip. Subsequently, the loss of coherency causes local softening and reduces fatigue life.

  8. Dislocation mean free paths and strain hardening of crystals.

    PubMed

    Devincre, B; Hoc, T; Kubin, L

    2008-06-27

    Predicting the strain hardening properties of crystals constitutes a long-standing challenge for dislocation theory. The main difficulty resides in the integration of dislocation processes through a wide range of time and length scales, up to macroscopic dimensions. In the present multiscale approach, dislocation dynamics simulations are used to establish a dislocation-based continuum model incorporating discrete and intermittent aspects of plastic flow. This is performed through the modeling of a key quantity, the mean free path of dislocations. The model is then integrated at the scale of bulk crystals, which allows for the detailed reproduction of the complex deformation curves of face-centered cubic crystals. Because of its predictive ability, the proposed framework has a large potential for further applications. PMID:18583605

  9. Theoretical Study of the Oxidation Behavior of Precipitation Hardening Steel

    SciTech Connect

    Pistofidis, N.; Vourlias, G.; Chrissafis, K.; Psyllaki, P.

    2010-01-21

    The oxidation of precipitation hardening (PH) steels is a rather unexplored area. In the present work an attempt is made is made to estimate the kinetics of a PH steel. For this purpose specimens of the material under examination were isothermally heated at 850, 900 and 950 deg. C for 15 hr. Kinetics was based on TGA results. During heating a thick scale is formed on the substrate surface, which is composed by different oxides. The layer close to the substrate is compact and as a result it impedes corrosion. The mathematical analysis of the collected data shows that the change of the mass of the substrate per unit area versus time is described by a parabolic law.

  10. Experience in calibrating the double-hardening constitutive model Monot

    NASA Astrophysics Data System (ADS)

    Hicks, M. A.

    2003-11-01

    The Monot double-hardening soil model has previously been implemented within a general purpose finite element algorithm, and used in the analysis of numerous practical problems. This paper reviews experience gained in calibrating Monot to laboratory data and demonstrates how the calibration process may be simplified without detriment to the range of behaviours modelled. It describes Monot's principal features, important governing equations and various calibration methods, including strategies for overconsolidated, cemented and cohesive soils. Based on a critical review of over 30 previous Monot calibrations, for sands and other geomaterials, trends in parameter values have been identified, enabling parameters to be categorized according to their relative importance. It is shown that, for most practical purposes, a maximum of only 5 parameters is needed; for the remaining parameters, standard default values are suggested. Hence, the advanced stress-strain modelling offered by Monot is attainable with a similar number of parameters as would be needed for some simpler, less versatile, models. Copyright

  11. Topographies of plasma-hardened surfaces of poly(dimethylsiloxane)

    SciTech Connect

    Goerrn, Patrick; Wagner, Sigurd

    2010-11-15

    We studied the formation of surface layers hardened by plasma-enhanced oxidation of the silicone elastomer poly(dimethylsiloxane). We explored the largest parameter space surveyed to date. The surface layers may wrinkle, crack, or both, under conditions that at times are controlled by design, but more often have been discovered by trial-and-error. We find four distinct topographies: flat/wrinkled/cracked/cracked and wrinkled. Each topography is clearly separated in the space of plasma dose versus plasma pressure. We analyzed wrinkle amplitude and wavelength by atomic force microscopy in the tapping mode. From these dimensions we calculated the elastic modulus and thickness of the hard surface layer, and inferred a graded hardness, by employing a modified theoretical model. Our main result is the identification of the parameters under which the technologically important pure wrinkled, crack-free topography is obtained.

  12. Gamma prime hardened nickel-iron based superalloy

    DOEpatents

    Korenko, Michael K.

    1978-01-01

    A low swelling, gamma prime hardened nickel-iron base superalloy useful for fast reactor duct and cladding applications is described having from about 7.0 to about 10.5 weight percent (wt%) chromium, from about 24 to about 35 wt% nickel, from about 1.7 to about 2.5 wt% titanium, from about 0.3 to about 1.0 wt% aluminum, from about 2.0 to about 3.3 wt% molybdenum, from about 0.05 to about 1.0 wt% silicon, from about 0.03 to about 0.06 wt% carbon, a maximum of about 2 wt% manganese, and the balance iron.

  13. A phenomenological model for bake hardening in minimal carbon steels

    NASA Astrophysics Data System (ADS)

    Das, Sourav; Nath Mohanty, Omkar; Brat Singh, Shiv

    2014-06-01

    The essence of bake hardening is to exploit the classical strain ageing in a positive way to increase the strength of the formed steel sheets used in outer body panel of a passenger car during the paint-baking operation. A new model that takes into account the strengthening contributions from Cottrell atmosphere and precipitate formation has been developed in the present work. The model predicts the increase in strength as a function of the amount of free solute C (calculated as a function of the annealing temperature), the amount of deformation, ageing temperature and time. The model predictions have been found to agree quite well with the experimental results; the individual contributions of Cottrell atmosphere and precipitation strengthening have been quantified.

  14. Analysis of fracture toughness of explosion-hardened martensitic steel

    NASA Astrophysics Data System (ADS)

    Moskvitina, L. V.

    2015-10-01

    In this work we study a shift of the following nonlinear states: tempering + abatement + 10 GPa shock loading + welding thermocycle. As a result the self-organized HAZ metal structure with elements of self-similarity on different scales is found. The fractal analysis shows how formed defects affect the HAZ metal hardness of 14H2GMR steel with the martensitic structure of static fracture. The statistical analysis of stereometric parameters of fracture shows a higher energy intensity of static fracture in specimens treated by explosion. The multifractal analysis reveals hardness of the grid dislocation structure induced by explosion in the air-hardening zone. The homogeneity of the dislocation structure related to carbides increases the resistance of HAZ metal of static fracture.

  15. Optical moments and the art of dispersion hardening

    NASA Astrophysics Data System (ADS)

    Sievers, A. J.; Noh, T. W.; Page, J. B.

    1994-06-01

    For many years composite structures have been the building blocks of materials with specialized mechanical properties, but only recently have related ideas been used successfully to develop new optical materials. A particularly simple example, hot pressed zinc sulfide dispersion hardened with diamond particles, has turned out to be extremely useful for identifying the important optical moments underlying the dynamical properties of all transparent composites and complex dielectrics. One result has been the discovery of a generalized Lyddane-Sachs-Teller relation for solids and liquids. When the characteristic frequencies of small disordered dielectric particles are described in terms of optical moments of the appropriate response functions, generalized Szigeti and Clausius-Mossotti expressions follow.

  16. Effective mineral coatings for hardening the surface of metallic materials

    NASA Astrophysics Data System (ADS)

    Kislov, S. V.; Kislov, V. G.; Skazochkin, A. V.; Bondarenko, G. G.; Tikhonov, A. N.

    2015-07-01

    The structural changes that occur in the surface and surface layers of steel 20Kh13 and titanium alloy PT-3V (Russian designation) samples after each stage of hardening due to a formed mineral surface layer are studied by optical microscopy, transmission electron microscopy, and scanning electron microscopy. Electric spark alloying, pressing, and ultrasonic processing are used to reach the effect of volume compression of the base metal and the mineral in the plastic deformation zone. As a result, applied mineral particles concentrate in preliminarily created microvoids in a thin surface layer. The surface layer thus modified acquires a high hardness and wear resistance. Durometry shows that the hardness of the processed sample surfaces increases more than twofold. Therefore, the developed technology of creating a mineral coating can be used to increase the tribological properties of the surfaces of the parts, units, and mechanisms of turbine, pump, and mining equipment, which undergo intense wear during operation.

  17. Laser shock-induced mechanical and microstructural modification of welded maraging steel

    SciTech Connect

    Banas, G. ); Elsayed-Ali, H.E. ); Lawrence, F.V. Jr. ); Rigsbee, J.M. )

    1990-03-01

    The effect of laser-induced high-intensity stress waves on the hardness, fatigue resistance, and microstructure in the heat affected zone of welded 18 Ni(250) maraging steel was investigated. Laser-shock processing increased the hardness and fatigue strength of the weldments. Some melting of the surface was involved during laser-shock hardening which produced the reverted austenite phase. Microscopic analyses showed an increased dislocation density in the laser-shocked area.

  18. Laser-based welding of 17-4 PH martensitic stainless steel in a tubular butt joint configuration with a built-in backing bar

    NASA Astrophysics Data System (ADS)

    Ma, Junjie; Atabaki, Mehdi Mazar; Liu, Wei; Pillai, Raju; Kumar, Biju; Vasudevan, Unnikrishnan; Kovacevic, Radovan

    2016-08-01

    Laser-based welding of thick 17-4 precipitation hardening (PH) martensitic stainless steel (SS) plates in a tubular butt joint configuration with a built-in backing bar is very challenging because the porosity and cracks are easily generated in the welds. The backing bar blocked the keyhole opening at the bottom surface through which the entrapped gas could escape, and the keyhole was unstable and collapsed overtime in a deep partially penetrated welding conditions resulting in the formation of pores easily. Moreover, the fast cooling rate prompted the ferrite transform to austenite which induced cracking. Two-pass welding procedure was developed to join 17-4 PH martensitic SS. The laser welding assisted by a filler wire, as the first pass, was used to weld the groove shoulder. The added filler wire could absorb a part of the laser beam energy; resulting in the decreased weld depth-to-width ratio and relieved intensive restraint at the weld root. A hybrid laser-arc welding or a gas metal arc welding (GMAW) was used to fill the groove as the second pass. Nitrogen was introduced to stabilize the keyhole and mitigate the porosity. Preheating was used to decrease the cooling rate and mitigate the cracking during laser-based welding of 17-4 PH martensitic SS plates.

  19. [Hardened anodized aluminum as a replacement material for bracket manufacture].

    PubMed

    Fischer-Brandies, H; Bönhoff, M

    1994-12-01

    Attention has been repeatedly drawn to the problem of corrosion and the risk of allergic reaction to nickel resulting from the use of stainless steel brackets. In the search for a suitable alternative, manufacturers have turned to thin coating technology using hardened anodized aluminium. Applying resistance to corrosion and abrasion as the criteria to be met, they have selected aluminium alloy type 6082 as the material of choice. Purpose of this study is to examine the physical suitability of this material. Using the above noted alloy, 60 prototype brackets were made with a hardened anodized surface. They were then subjected to the following 3 stress tests: first an abrasion test using a tooth polishing machine, second, a deformation test using a device designed to simulate torque movement, and, third, a corrosion test. The effects on the brackets resulting from the three types of stress were evaluated by light microscopy. A quantitative analysis of the corrosion test was performed by ICP spectrometry. The control group consisted of conventional stainless steel brackets. The light microscopic analysis revealed no evidence of surface damage or signs of deformation in the prototype brackets. The steel brackets, on the other hand, showed clear signs of wear and corrosion. The quantitative analysis of the corrosion solution revealed metallic ion wear of 1.75 ng x mm-2 x h-1 for the prototypes subjected to abrasion. The steel brackets showed at a factor of around 104.6 metallic ion wear of 183 ng x mm-2 x h-1. In addition to this, no Ni ions were found in the corrosion solution of the prototype brackets.(ABSTRACT TRUNCATED AT 250 WORDS) PMID:7851828

  20. Radiation Effects and Hardening Techniques for Spacecraft Microelectronics

    NASA Astrophysics Data System (ADS)

    Gambles, J. W.; Maki, G. K.

    2002-01-01

    The natural radiation from the Van Allen belts, solar flares, and cosmic rays found outside of the protection of the earth's atmosphere can produce deleterious effects on microelectronics used in space systems. Historically civil space agencies and the commercial satellite industry have been able to utilize components produced in special radiation hardened fabrication process foundries that were developed during the 1970s and 1980s under sponsorship of the Departments of Defense (DoD) and Energy (DoE). In the post--cold war world the DoD and DoE push to advance the rad--hard processes has waned. Today the available rad--hard components lag two-plus technology node generations behind state- of-the-art commercial technologies. As a result space craft designers face a large performance gap when trying to utilize available rad--hard components. Compounding the performance gap problems, rad--hard components are becoming increasingly harder to get. Faced with the economic pitfalls associated with low demand versus the ever increasing investment required for integrated circuit manufacturing equipment most sources of rad--hard parts have simply exited this market in recent years, leaving only two domestic US suppliers of digital rad--hard components. This paper summarizes the radiation induced mechanisms that can cause digital microelectronics to fail in space, techniques that can be applied to mitigate these failure mechanisms, and ground based testing used to validate radiation hardness/tolerance. The radiation hardening techniques can be broken down into two classes, Hardness By Process (HBP) and Hardness By Design (HBD). Fortunately many HBD techniques can be applied to commercial fabrication processes providing space craft designer with radiation tolerant Application Specific Integrated Circuits (ASICs) that can bridge the performance gap between the special HBP foundries and the commercial state-of-the-art performance.

  1. Development of a Press-Hardened Steel Suitable for Thin Slab Direct Rolling Processing

    NASA Astrophysics Data System (ADS)

    Lee, Jewoong; De Cooman, Bruno C.

    2015-01-01

    The thin slab casting and direct rolling process is a hot-rolled strip production method which has maintained commercial quality steel grades as a major material in many industrial applications due to its low processing cost. Few innovative products have however been developed specifically for production by thin slab direct rolling. Press hardening or hot press forming steel grades which are now widely used to produce structural automotive steel parts requiring ultra-high strength and formability may however offer an opportunity for thin slab direct rolling-specific ultra-high strength products. In this work, a newly designed press hardening steel grade developed specifically for thin slab direct rolling processing is presented. The press hardening steel has a high nitrogen content compared with press hardening steel grades produced by conventional steelmaking routes. Boron and titanium which are key alloying additions in conventional press hardening steel such as the 22MnB5 press hardening steel grade are not utilized. Cr is added in the press hardening steel to obtain the required hardenability. The properties of the new thin slab direct rolling-specific 22MnCrN5 press hardening steel grade are reviewed. The evolution of the microstructure and mechanical properties with increasing amounts of Cr additions from 0.6 to 1.4 wt pct and the effect of the cooling rate during die-quenching were studied by means of laboratory simulations. The selection of the optimum chemical composition range for the thin slab direct rolling-specific 22MnCrN5 steel in press hardening heat treatment conditions is discussed.

  2. Potential role of strain hardening in the cessation of rifting at constant tectonic force

    NASA Astrophysics Data System (ADS)

    Yamasaki, Tadashi; Stephenson, Randell

    2009-01-01

    In this study the cessation of rifting at constant tectonic force is discussed from the viewpoint of lithospheric rheology using a simple one-dimensional numerical model. The behaviour of the conventionally adopted constant force model re-examined in this study contradicts some general features in the development of sedimentary basins. Strain hardening is implemented to explain the contradictions, in which the viscosity of the mantle is a function of not only the strain rate and temperature but also the total strain. The roles of various strain hardening parameters in rifting dynamics are examined, including the strain required for the onset of hardening, the strain interval required for the completion of hardening and the factor controlling the increase in mantle viscosity. It is shown that a model with strain hardening can explain many characteristic features of sedimentary basin formation better than the conventional constant force model. There are a variety of ways in which rifting can be terminated by the strain hardening model, depending on the initial lithospheric structure, magnitude of tectonic force and the hardening process. One possible strain hardening mechanism involves the switch from wet to dry rheology associated with decompressional melting, though the implemented strain hardening formula could be generally applicable to any hardening phenomenon and could therefore be physically interpreted as such. The results of this study also provide important insights into sedimentary basin subsidence in relation to rifting dynamics. The end of an initial rapid ("syn-rift" like) subsidence phase is not necessarily equivalent to the end of actual rifting as in the constant force model. The transition from initial rapid subsidence to long-term, more subdued ("post-rift" like), subsidence is actually marked by the onset of deceleration of rifting. Since significant extension still continues for some time thereafter, the subsequent long-term subsidence includes

  3. Reading Transformation

    ERIC Educational Resources Information Center

    Reeves, Melinda

    2006-01-01

    The parents of students who attend Decatur High School thought that there was little hope of their kids going on to college. After a year or so in Decatur's reading program, their sons and daughters were both transformed and college bound. In this article, the author describes how Decatur was able to successfully transform their students. Seven…

  4. Experimental Investigations of the Internal Energy of Molecules Evaporated via Laser-induced Acoustic Desorption into a Fourier-transform Ion Cyclotron Resonance Mass Spectrometer (LIAD/FT-ICR)

    PubMed Central

    Shea, Ryan C.; Petzold, Christopher J.; Liu, Ji-ang; Kenttämaa, Hilkka I.

    2008-01-01

    The internal energy of neutral gas-phase organic and biomolecules, evaporated by means of laser-induced acoustic desorption (LIAD) into a Fourier-transform ion cyclotron resonance mass spectrometer (FT-ICR), was investigated through several experimental approaches. The desorbed molecules were demonstrated not to undergo degradation during the desorption process by collecting LIAD-evaporated molecules and subjecting them to analysis by electrospray ionization/quadrupole ion trap mass spectrometry. Previously established gas-phase basicity (GB) values were remeasured for LIAD-evaporated organic molecules and biomolecules with the use of the bracketing method. No endothermic reactions were observed. The remeasured basicity values are in close agreement with the values reported in the literature. The amount of internal energy deposited during LIAD is concluded to be less than a few kcal/mol. Chemical ionization with a series of proton transfer reagents was employed to obtain a breakdown curve for a protonated dipeptide, val-pro, evaporated by LIAD. Comparison of this breakdown curve with a previously published analogous curve obtained by using substrate-assisted laser desorption (SALD) to evaporate the peptide suggests that the molecules evaporated via LIAD have less internal energy than those evaporated via SALD. PMID:17263513

  5. Characterization of radiation-induced products of thymidine 3{prime}-monophosphate and thymidylyl (3{prime}{yields}5{prime}) thymidine by high-performance liquid chromatography and laser-desorption fourier-transform mass spectrometry

    SciTech Connect

    Yoshida, H.; Hettich, R.L.

    1994-09-01

    High-performance liquid chromatography (HPLC) and laser-desorption Fourier-transform mass spectrometry (LD FTMS) have been applied for direct measurements of radiation-induced products of nucleic acid constituents containing thymidine. Laser desorption FTMS could be used for the direct detection (neither hydrolyzed nor derivatized) of X-ray-induced decomposition products of aqueous thymidine monophosphate. After these initial experiments, a variety of hydrogenated and hydroxylated thymine standards were acquired and examined by FTMS to assist in the identification of unknown radiation-induced decomposition products of thymine-containing nucleotides and dinucleotides. To extend these studies to dinucleotides, the radiation-induced products generated by the gamma radiolysis of thymidylyl (3{prime}{yields}5{prime}) thymidine (TpT) were isolated by reverse-phase HPLC and identified by LD FTMS. Thymine and thymidine 3{prime}-monophosphate were observed as the major products in this case. Several of the minor products of the HPLC profile were pooled in a single fraction and characterized simultaneously by LD FTMS. The resulting mass spectra indicated the presence of hydroxy-5,6-dihydothymidine monophosphate, 5,6-dihydrothymidine monophosphate and thymidine monophosphate, thymine glycol, hydroxy-5,6-dihydrothymine, 5-hydroxy-methyl-uracil and 5,6-dihydrothymine. The combination of HPLC purification and LD FTMS structural characterization provides a useful tool for the direct measurement of radiation-induced products of nucleotides and dinucleotides. 28 refs., 6 figs., 2 tabs.

  6. Reversible nanodiamond-carbon onion phase transformations.

    PubMed

    Xiao, J; Ouyang, G; Liu, P; Wang, C X; Yang, G W

    2014-06-11

    Because of their considerable science and technical interest, nanodiamonds (3-5 nm) are often used as a model to study the phase transformation between graphite and diamond. Here we demonstrated that a reversible nanodiamond-carbon onion phase transformation can become true when laser irradiates colloidal suspensions of nanodiamonds at the ambient temperature and pressure. Nanodiamonds are first transformed to carbon onions driven by the laser-induced high temperature in which an intermediary bucky diamond phase is observed. Sequentially, carbon onions are transformed back to nanodiamonds driven by the laser-induced high temperature and high pressure from carbon onions as nanoscaled temperature and pressure cell upon the laser irradiation process in liquid. Similarly, the same bucky diamond phase serving as an intermediate phase is found during the carbon onion-to-nanodiamond transition. To have a clear insight into the unique phase transformation the thermodynamic approaches on the nanoscale were proposed to elucidate the reversible phase transformation of nanodiamond-to-carbon onion-to-nanodiamond via an intermediary bucky diamond phase upon the laser irradiation in liquid. This reversible transition reveals a series of phase transformations between diamond and carbon allotropes, such as carbon onion and bucky diamond, having a general insight into the basic physics involved in these phase transformations. These results give a clue to the root of meteoritic nanodiamonds that are commonly found in primitive meteorites but their origin is puzzling and offers one suitable approach for breaking controllable pathways between diamond and carbon allotropes. PMID:24823241

  7. Computer simulation of residual stresses/distortion and structural change in the course of scanning induction hardening

    SciTech Connect

    Ikuta, F.; Arimoto, K.; Inoue, T.

    1996-12-31

    Simulated results of structural change, residual stresses and distortion are presented for carbon steel cylinder in the scanning-type induction hardening process by a CAE system {open_quotes}HEARTS (HEAt tReaTment Simulation system){close_quotes}. The system HEARTS has been developed to simulate heat treatment processes based on {open_quotes}metallo-thermo-mechanics{close_quotes} available for describing the coupling effect between metallurgical change due to phase transformation, temperature and inelastic stress/strain. A steel cylinder is treated as an axisymmetric model with scanning internal heat generation and convection boundary. The results under different scanning velocity and magnitude of the heat source from induction coil are compared with experimental data of distortions, volume fraction of metallic phases as well as residual stresses.

  8. Effect of Peculiarities of Heat Transfer, Diffusion and Phase Transformation on Joint Formation During Welding of Dissimilar Materials by High Power Fiber Laser

    NASA Astrophysics Data System (ADS)

    Turichin, Gleb; Klimova, Olga; Valdaytseva, Ekaterina

    The article describes mathematical models of diffusion and thermal processes for welding of dissimilar materials and kinetic model of diffusion-controlled deposition and growth of intermetallic inclusions in the weld. Developed models were combined and implemented in the model of weld joint formation for dissimilar materials. To verify a model the microstructure analysis of weld joints and elemental analysis in the diffusion zone by SEM has been made for welding of systems Fe-Cu, Al-Ti, Fe-Al. The good agreement between calculated and experimental data has been obtained. Examples of developed technologies of welding of dissimilar materials using high-power fiber lasers were discussed also.

  9. Contribution to the beam plasma material interactions during material processing with TEA CO2 laser radiation

    NASA Astrophysics Data System (ADS)

    Jaschek, Rainer; Konrad, Peter E.; Mayerhofer, Roland; Bergmann, Hans W.; Bickel, Peter G.; Kowalewicz, Roland; Kuttenberger, Alfred; Christiansen, Jens

    1995-03-01

    The TEA-CO2-laser (transversely excited atmospheric pressure) is a tool for the pulsed processing of materials with peak power densities up to 1010 W/cm2 and a FWHM of 70 ns. The interaction between the laser beam, the surface of the work piece and the surrounding atmosphere as well as gas pressure and the formation of an induced plasma influences the response of the target. It was found that depending on the power density and the atmosphere the response can take two forms. (1) No target modification due to optical break through of the atmosphere and therefore shielding of the target (air pressure above 10 mbar, depending on the material). (2) Processing of materials (air pressure below 10 mbar, depending on the material) with melting of metallic surfaces (power density above 0.5 109 W/cm2), hole formation (power density of 5 109 W/cm2) and shock hardening (power density of 3.5 1010 W/cm2). All those phenomena are usually linked with the occurrence of laser supported combustion waves and laser supported detonation waves, respectively for which the mechanism is still not completely understood. The present paper shows how short time photography and spatial and temporal resolved spectroscopy can be used to better understand the various processes that occur during laser beam interaction. The spectra of titanium and aluminum are observed and correlated with the modification of the target. If the power density is high enough and the gas pressure above a material and gas composition specific threshold, the plasma radiation shows only spectral lines of the background atmosphere. If the gas pressure is below this threshold, a modification of the target surface (melting, evaporation and solid state transformation) with TEA-CO2- laser pulses is possible and the material specific spectra is observed. In some cases spatial and temporal resolved spectroscopy of a plasma allows the calculation of electron temperatures by comparison of two spectral lines.

  10. Surface properties of low alloy steel treated by plasma nitrocarburizing prior to laser quenching process

    NASA Astrophysics Data System (ADS)

    Wang, Y. X.; Yan, M. F.; Li, B.; Guo, L. X.; Zhang, C. S.; Zhang, Y. X.; Bai, B.; Chen, L.; Long, Z.; Li, R. W.

    2015-04-01

    Laser quenching (LQ) technique is used as a part of duplex treatments to improve the thickness and hardness of the surface layers of steels. The present study is to investigate the surface properties of low alloy steel treated by plasma nitrocarburizing (PNC) prior to a laser quenching process (PNC+LQ). The microstructure and properties of PNC+LQ layer determined are compared with those obtained by PNC and LQ processes. OM, XRD, SEM and EDS analyses are utilized for microstructure observation, phases identification, morphology observation and chemical composition detection, respectively. Microhardness tester and pin-on-disc tribometer are used to investigate the mechanical properties of the modified layers. Laser quenching of plasma nitrocarburized (PNC+LQ) steel results in much improved thickness and hardness of the modified layer in comparison with the PNC or LQ treated specimens. The mechanism is that the introduction of trace of nitrogen decreases the eutectoid point, that is, the transformation hardened region is enlarged under the same temperature distribution. Moreover, the layer treated by PNC+LQ process exhibits enhanced wear resistance, due to the lubrication effect and optimized impact toughness, which is contributed to the formation of oxide film consisting of low nitrogen compound (FeN0.076) and iron oxidation (mainly of Fe3O4).

  11. Laser Phase Errors in Seeded Free Electron Lasers

    SciTech Connect

    Ratner, D.; Fry, A.; Stupakov, G.; White, W.; /SLAC

    2012-04-17

    Harmonic seeding of free electron lasers has attracted significant attention as a method for producing transform-limited pulses in the soft x-ray region. Harmonic multiplication schemes extend seeding to shorter wavelengths, but also amplify the spectral phase errors of the initial seed laser, and may degrade the pulse quality and impede production of transform-limited pulses. In this paper we consider the effect of seed laser phase errors in high gain harmonic generation and echo-enabled harmonic generation. We use simulations to confirm analytical results for the case of linearly chirped seed lasers, and extend the results for arbitrary seed laser envelope and phase.

  12. Tradeoffs in Flight Design Upset Mitigation in State of the Art FPGAs: Hardened by Design vs. Design Level Hardening

    NASA Technical Reports Server (NTRS)

    Swift, Gary M.; Roosta, Ramin

    2004-01-01

    This presentation compares and contrasts the effectiveness and the system/designer impacts of the two main approaches to upset hardening: the Actel approach (RTSX-S and RTAX-S) of low-level (inside each flip-flop) triplication and the Xilinx approach (Virtex and Virtex2) of design-level triplication of both functional blocks and voters. The effectiveness of these approaches is compared using measurements made in conjunction with each of the FPGAs' manufacturer: for Actel, published data [1] and for Xilinx, recent results from the Xilinx SEE Test Consortium (note that the author is an active and founding member). The impacts involve Actel advantages in the areas of transistor-utilization efficiency and minimizing designer involvement in the triplication while the Xilinx advantages relate to the ability to custom tailor upset hardness and the flexibility of re-configurability. Additionally, there are currently clear Xilinx advantages in available features such as the number of I/O's, logic cells, and RAM blocks as well as speed. However, the advantage of the Actel anti-fuses for configuration over the Xilinx SRAM cells is that the latter need additional functionality and external circuitry (PROMs and, at least a watchdog timer) for configuration and configuration scrubbing. Further, although effectively mitigated if done correctly, the proton upset-ability of the Xilinx FPGAs is a concern in severe proton-rich environments. Ultimately, both manufacturers' upset hardening is limited by SEFI (single-event functional interrupt) rates where it appears the Actel results are better although the Xilinx Virtex2-family result of about one SEFI in 65 device-years in solar-min GCR (the more intense part of the galactic cosmic-ray background) should be acceptable to most missions

  13. Lightweight transformer

    SciTech Connect

    Swallom, D.W.; Enos, G.

    1990-05-01

    The technical effort described in this report relates to the program that was performed to design, fabricate, and test a lightweight transformer for Strategic Defense Initiative Organization (SDIO) mission requirements. The objectives of this program were two-fold: (1) design and fabricate a lightweight transformer using liquid hydrogen as the coolant; and (2) test the completed transformer assembly with a low voltage, dc power source. Although the full power testing with liquid helium was not completed, the program demonstrated the viability of the design approach. The lightweight transformer was designed and fabricated, and low and moderate power testing was completed. The transformer is a liquid hydrogen cooled air core transformer that uses thin copper for its primary and secondary windings. The winding mass was approximately 12 kg, or 0.03 kg/kW. Further refinements of the design to a partial air core transformer could potentially reduce the winding mass to as low as 4 or 5 kg, or 0.0125 kg/kW. No attempt was made on this program to reduce the mass of the related structural components or cryogenic container. 8 refs., 39 figs., 2 tabs.

  14. Carbide transformations in constructional steels

    SciTech Connect

    Vinokur, B.B.

    1986-01-01

    In connection with the type of carbides formed in general purpose constructional steels or on the mechanisms of carbide transformations and the influence of carbide formation on the properties, this work presents an investigation that was made of medium-carbon chrome-nickel and chrome-manganese steels with 1, 2, and 3% Cr, 1% Ni, and 1% Mn additionally alloyed with 0.25-2% Mo or W (every 0.25%). All of the steels were hardened from temperatures providing the fullest solution of carbides in austenite and were tempered at 400-650/sup 0/C every 25-50/sup 0/C. The composition of the carbides and their type were established by chemical, x-ray diffraction, and microdiffraction methods and the mechanism of the carbide transformations was determined on the basis of the changes in distortions of the second and third order of the matrix electrical resistance, and coercive force of the steel. All of the carbideforming elements present in steel participate in saturation of the carbides, as a result of which the formation of a special carbide is eased and the degree of alloying of the matrix increases. In the carbide transformation with a certain share of carbide phase an increase or retarding of the reduction in strength with an increase in tempering temperature with constant plasticity and impact strength is possible.

  15. Analysis of Obstacle Hardening Models Using Dislocation Dynamics: Application to Irradiation-Induced Defects

    NASA Astrophysics Data System (ADS)

    Sobie, Cameron; Bertin, Nicolas; Capolungo, Laurent

    2015-08-01

    Irradiation hardening in -iron represents a critical factor in nuclear reactor design and lifetime prediction. The dispersed barrier hardening, Friedel Kroupa Hirsch (FKH), and Bacon Kocks Scattergood (BKS) models have been proposed to predict hardening caused by dislocation obstacles in metals, but the limits of their applicability have never been investigated for varying defect types, sizes, and densities. In this work, dislocation dynamics calculations of irradiation-induced obstacle hardening in the athermal case were compared to these models for voids, self-interstitial atom (SIA) loops, and a combination of the two types. The BKS model was found to accurately predict hardening due to voids, whereas the FKH model was superior for SIA loops. For both loops and voids, the hardening from a normal distribution of defects was compared to that from the mean size, and was shown to have no statistically significant dependence on the distribution. A mean size approach was also shown to be valid for an asymmetric distribution of voids. A non-linear superposition principle was shown to predict the hardening from the simultaneous presence of voids and SIA loops.

  16. Modeling of the Effect of Path Planning on Thermokinetic Evolutions in Laser Powder Deposition Process

    NASA Astrophysics Data System (ADS)

    Foroozmehr, Ehsan; Kovacevic, Radovan

    2011-07-01

    A thermokinetic model coupling finite-element heat transfer with transformation kinetics is developed to determine the effect of deposition patterns on the phase-transformation kinetics of laser powder deposition (LPD) process of a hot-work tool steel. The finite-element model is used to define the temperature history of the process used in an empirical-based kinetic model to analyze the tempering effect of the heating and cooling cycles of the deposition process. An area is defined to be covered by AISI H13 on a substrate of AISI 1018 with three different deposition patterns: one section, two section, and three section. The two-section pattern divides the area of the one-section pattern into two sections, and the three-section pattern divides that area into three sections. The results show that dividing the area under deposition into smaller areas can influence the phase transformation kinetics of the process and, consequently, change the final hardness of the deposited material. The two-section pattern shows a higher average hardness than the one-section pattern, and the three-section pattern shows a fully hardened surface without significant tempered zones of low hardness. To verify the results, a microhardness test and scanning electron microscope were used.

  17. Conformational Transformations of Hemoglobin Molecules During in vivo Blood Irradiation by Low-Intensity Laser Radiation in the Red and Near IR Ranges

    NASA Astrophysics Data System (ADS)

    Zalesskaya, G. A.

    2014-07-01

    The effect of in vivo blood irradiation by low-intensity laser radiation on electronic-conformational interactions in hemoglobin molecules has been studied experimentally. The changes in the electronic and IR absorption spectra were followed for blood samples drawn at specific times during intravenous and supravascular irradiation, and also after dark reactions have occurred. The nature of the spectral changes observed is discussed. It is shown that the reversible photodissociation of hemoglobin-ligand complexes, initiated by blood irradiation, changes the oxyhemoglobin and deoxyhemoglobin levels, which leads to changes in the electronic absorption spectra of the blood and erythrocytes, and all the conformational transitions in the hemoglobin macromolecules accompanying ligand detachment and addition are responsible for the changes in their IR spectra.

  18. Effects of Ce additions on the age hardening response of Mg–Zn alloys

    SciTech Connect

    Langelier, Brian Esmaeili, Shahrzad

    2015-03-15

    The effects of Ce additions on the precipitation hardening behaviour of Mg–Zn are examined for a series of alloys, with Ce additions at both alloying and microalloying levels. The alloys are artificially aged, and studied using hardness measurement and X-ray diffraction, as well as optical and transmission electron microscopy. It is found that the age-hardening effect is driven by the formation of fine precipitates, the number density of which is related to the Zn content of the alloy. Conversely, the Ce content is found to slightly reduce hardening. When the alloy content of Ce is high, large secondary phase particles containing both Ce and Zn are present, and remain stable during solutionizing. These particles effectively reduce the amount of Zn available as solute for precipitation, and thereby reduce hardening. Combining hardness results with thermodynamic analysis of alloy solute levels also suggests that Ce can have a negative effect on hardening when present as solutes at the onset of ageing. This effect is confirmed by designing a pre-ageing heat treatment to preferentially remove Ce solutes, which is found to restore the hardening capability of an Mg–Zn–Ce alloy to the level of the Ce-free alloy. - Highlights: • The effects of Ce additions on precipitation in Mg–Zn alloys are examined. • Additions of Ce to Mg–Zn slightly reduce the age-hardening response. • Ce-rich secondary phase particles deplete the matrix of Zn solute. • Hardening is also decreased when Ce is present in solution. • Pre-ageing to preferentially precipitate out Ce restores hardening capabilities.

  19. Triple transformation

    NASA Astrophysics Data System (ADS)

    Khan, Farrukh I.; Schinn, Dustin S.

    2013-08-01

    A new business plan that enables policy transformation and resource mobilization at the national and international level, while improving access to resources, will allow the Green Climate Fund to integrate development goals and action on climate change.

  20. Non Radiation Hardened Microprocessors in Spaced Based Remote Sensing Systems

    NASA Technical Reports Server (NTRS)

    Decoursey, Robert J.; Estes, Robert F.; Melton, Ryan

    2006-01-01

    The CALIPSO (Cloud-Aerosol Lidar and Infrared Pathfinder Satellite Observations) mission is a comprehensive suite of active and passive sensors including a 20Hz 230mj Nd:YAG lidar, a visible wavelength Earth-looking camera and an imaging infrared radiometer. CALIPSO flies in formation with the Earth Observing System Post-Meridian (EOS PM) train, provides continuous, near-simultaneous measurements and is a planned 3 year mission. CALIPSO was launched into a 98 degree sun synchronous Earth orbit in April of 2006 to study clouds and aerosols and acquires over 5 gigabytes of data every 24 hours. The ground track of one CALIPSO orbit as well as high and low intensity South Atlantic Anomaly outlines is shown. CALIPSO passes through the SAA several times each day. Spaced based remote sensing systems that include multiple instruments and/or instruments such as lidar generate large volumes of data and require robust real-time hardware and software mechanisms and high throughput processors. Due to onboard storage restrictions and telemetry downlink limitations these systems must pre-process and reduce the data before sending it to the ground. This onboard processing and realtime requirement load may mean that newer more powerful processors are needed even though acceptable radiation-hardened versions have not yet been released. CALIPSO's single board computer payload controller processor is actually a set of four (4) voting non-radiation hardened COTS Power PC 603r's built on a single width VME card by General Dynamics Advanced Information Systems (GDAIS). Significant radiation concerns for CALIPSO and other Low Earth Orbit (LEO) satellites include the South Atlantic Anomaly (SAA), the north and south poles and strong solar events. Over much of South America and extending into the South Atlantic Ocean the Van Allen radiation belts dip to just 200-800km and spacecraft entering this area are subjected to high energy protons and experience higher than normal Single Event Upset

  1. Covariant Transform

    NASA Astrophysics Data System (ADS)

    Kisil, Vladimir V.

    2011-03-01

    Dedicated to the memory of Cora Sadosky The paper develops theory of covariant transform, which is inspired by the wavelet construction. It was observed that many interesting types of wavelets (or coherent states) arise from group representations which are not square integrable or vacuum vectors which are not admissible. Covariant transform extends an applicability of the popular wavelets construction to classic examples like the Hardy space H2, Banach spaces, covariant functional calculus and many others.

  2. NINJA: a noninvasive framework for internal computer security hardening

    NASA Astrophysics Data System (ADS)

    Allen, Thomas G.; Thomson, Steve

    2004-07-01

    Vulnerabilities are a growing problem in both the commercial and government sector. The latest vulnerability information compiled by CERT/CC, for the year ending Dec. 31, 2002 reported 4129 vulnerabilities representing a 100% increase over the 2001 [1] (the 2003 report has not been published at the time of this writing). It doesn"t take long to realize that the growth rate of vulnerabilities greatly exceeds the rate at which the vulnerabilities can be fixed. It also doesn"t take long to realize that our nation"s networks are growing less secure at an accelerating rate. As organizations become aware of vulnerabilities they may initiate efforts to resolve them, but quickly realize that the size of the remediation project is greater than their current resources can handle. In addition, many IT tools that suggest solutions to the problems in reality only address "some" of the vulnerabilities leaving the organization unsecured and back to square one in searching for solutions. This paper proposes an auditing framework called NINJA (acronym for Network Investigation Notification Joint Architecture) for noninvasive daily scanning/auditing based on common security vulnerabilities that repeatedly occur in a network environment. This framework is used for performing regular audits in order to harden an organizations security infrastructure. The framework is based on the results obtained by the Network Security Assessment Team (NSAT) which emulates adversarial computer network operations for US Air Force organizations. Auditing is the most time consuming factor involved in securing an organization's network infrastructure. The framework discussed in this paper uses existing scripting technologies to maintain a security hardened system at a defined level of performance as specified by the computer security audit team. Mobile agents which were under development at the time of this writing are used at a minimum to improve the noninvasiveness of our scans. In general, noninvasive

  3. Deformable mirror for high power laser applications

    NASA Astrophysics Data System (ADS)

    Mrň; a, Libor; Sarbort, Martin; Hola, Miroslava

    2015-01-01

    The modern trend in high power laser applications such as welding, cutting and surface hardening lies in the use of solid-state lasers. The output beam of these lasers is characterized by a Gaussian intensity distribution. However, the laser beams with different intensity distributions, e.g. top-hat, are preferable in various applications. In this paper we present a new type of deformable mirror suitable for the corresponding laser beam shaping. The deformation of the mirror is achieved by an underlying array of actuators and a pressurized coolant that also provides the necessary cooling. We describe the results of the surface shape measurement using a 3D scanner for different settings of actuators. Further, we show the achieved intensity distributions measured by a beam profiler for a low power laser beam reflected from the mirror.

  4. Hardening/finishing treatment of compressor blades using a machine with planetary container motion

    NASA Astrophysics Data System (ADS)

    Shpatakovskii, A. F.

    A process for the hardening and finishing of high-pressure compressor blades for aircraft powerplants is described whereby the blades are placed in containers that move along a planetary path in a hardening medium consisting of steel balls. The extent of surface hardening, surface roughness, and residual stresses are determined for specimens of U8A steel and blades of EP718VD alloy treated under different conditions. The efficiency of the treatment in terms of increased blade durability and productivity is estimated.

  5. Developments in Radiation-Hardened Electronics Applicable to the Vision for Space Exploration

    NASA Technical Reports Server (NTRS)

    Keys, Andrew S.; Frazier, Donald O.; Patrick , Marshall C.; Watson, Michael D.; Johnson, Michael A.; Cressler, John D.; Kolawa, Elizabeth A.

    2007-01-01

    The Radiation Hardened Electronics for Space Exploration (RHESE) project develops the advanced technologies required to produce radiation hardened electronics, processors, and devices in support of the anticipated requirements of NASA's Constellation program. Methods of protecting and hardening electronics against the encountered space environment are discussed. Critical stages of a spaceflight mission that are vulnerable to radiation-induced interruptions or failures are identified. Solutions to mitigating the risk of radiation events are proposed through the infusion of RHESE technology products and deliverables into the Constellation program's spacecraft designs.

  6. Transforming the optical landscape.

    PubMed

    Pendry, J B; Luo, Yu; Zhao, Rongkuo

    2015-05-01

    Electromagnetism provides us with some of the most powerful tools in science, encompassing lasers, optical microscopes, magnetic resonance imaging scanners, radar, and a host of other techniques. To understand and develop the technology requires more than a set of formal equations. Scientists and engineers have to form a vivid picture that fires their imaginations and enables intuition to play a full role in the process of invention. It is to this end that transformation optics has been developed, exploiting Faraday's picture of electric and magnetic fields as lines of force, which can be manipulated by the electrical permittivity and magnetic permeability of surrounding materials. Transformation optics says what has to be done to place the lines of force where we want them to be. PMID:25931549

  7. Transforming the optical landscape

    NASA Astrophysics Data System (ADS)

    Pendry, J. B.; Luo, Yu; Zhao, Rongkuo

    2015-05-01

    Electromagnetism provides us with some of the most powerful tools in science, encompassing lasers, optical microscopes, magnetic resonance imaging scanners, radar, and a host of other techniques. To understand and develop the technology requires more than a set of formal equations. Scientists and engineers have to form a vivid picture that fires their imaginations and enables intuition to play a full role in the process of invention. It is to this end that transformation optics has been developed, exploiting Faraday’s picture of electric and magnetic fields as lines of force, which can be manipulated by the electrical permittivity and magnetic permeability of surrounding materials. Transformation optics says what has to be done to place the lines of force where we want them to be.

  8. High Energy 2-Micron Laser Developments

    NASA Technical Reports Server (NTRS)

    Yu, Jirong; Trieu, Bo C.; Petros, Mulugeta; Bai, Yingxin; Petzar, Paul J.; Koch, Grady J.; Singh, Upendra N.; Kavaya, Michael J.

    2007-01-01

    A master oscillator power amplifier, high energy Q-switched 2-micron laser system has been recently demonstrated. The laser and amplifiers are all designed in side-pumped rod configuration, pumped by back-cooled conductive packaged GaAlAs diode laser arrays. This 2-micron laser system provides nearly transform limited beam quality.

  9. Dynamic response of two strain-hardened aluminum alloys

    NASA Astrophysics Data System (ADS)

    Boteler, J. M.; Dandekar, D. P.

    2006-09-01

    Despite their common usage in armor applications such as lightweight armored vehicles, the dynamic material response of 5083-H131 and 5083-H32 strain-hardened aluminum alloys has not been previously reported in the open literature. Measurement of the dynamic material properties, including the shock Hugoniot equation of state (EOS), provides hydrocode modelers with critical information required for accurate modeling of material response to intense loading. In the work reported here we investigate the Hugoniot EOS and Hugoniot elastic limit over the stress range of 1.5-8.0GPa. All experiments were performed on the Army Research Laboratory 102mm bore single-stage light gas gun. Impact conditions were uniaxial and planar to within 1mrad of tilt. Both direct-impact- and shock-transmission-type experiments were performed using velocity interferometry diagnostics to record particle velocity histories with 0.5ns temporal resolution. The shock Hugoniot for 5083-H131 is extrapolated to 50GPa and compared to the previous high pressure results of Hauver and Melani (1973) [Ballistic Research Laboratory December Technical Report No. BRL 2345, 1973] and to prior shock studies of 5083-O aluminum alloy.

  10. Waste tyre rubberized concrete: properties at fresh and hardened state.

    PubMed

    Aiello, M A; Leuzzi, F

    2010-01-01

    The main objective of this paper is to investigate the properties of various concrete mixtures at fresh and hardened state, obtained by a partial substitution of coarse and fine aggregate with different volume percentages of waste tyres rubber particles, having the same dimensions of the replaced aggregate. Workability, unit weight, compressive and flexural strength and post-cracking behaviour were evaluated and a comparison of the results for the different rubcrete mixtures were proposed in order to define the better mix proportions in terms of mechanical properties of the rubberized concrete. Results showed in this paper were also compared to data reported in literature. Moreover, a preliminary geometrical, physical and mechanical characterization on scrap tyre rubber shreds was made. The rubberized concrete mixtures showed lower unit weight compared to plain concrete and good workability. The results of compressive and flexural tests indicated a larger reduction of mechanical properties of rubcrete when replacing coarse aggregate rather than fine aggregate. On the other hand, the post-cracking behaviour of rubberized concrete was positively affected by the substitution of coarse aggregate with rubber shreds, showing a good energy absorption and ductility indexes in the range observed for fibrous concrete, as suggested by standard (ASTM C1018-97, 1997). PMID:20207128

  11. Switchable hardening of a ferromagnet at fixed temperature.

    PubMed

    Silevitch, D M; Aeppli, G; Rosenbaum, T F

    2010-02-16

    The intended use of a magnetic material, from information storage to power conversion, depends crucially on its domain structure, traditionally crafted during materials synthesis. By contrast, we show that an external magnetic field, applied transverse to the preferred magnetization of a model disordered uniaxial ferromagnet, is an isothermal regulator of domain pinning. At elevated temperatures, near the transition into the paramagnet, modest transverse fields increase the pinning, stabilize the domain structure, and harden the magnet, until a point where the field induces quantum tunneling of the domain walls and softens the magnet. At low temperatures, tunneling completely dominates the domain dynamics and provides an interpretation of the quantum phase transition in highly disordered magnets as a localization/delocalization transition for domain walls. While the energy scales of the rare earth ferromagnet studied here restrict the effects to cryogenic temperatures, the principles discovered are general and should be applicable to existing classes of highly anisotropic ferromagnets with ordering at room temperature or above. PMID:20133728

  12. Yield Hardening of Electrorheological Fluids in Channel Flow

    NASA Astrophysics Data System (ADS)

    Helal, Ahmed; Qian, Bian; McKinley, Gareth H.; Hosoi, A. E.

    2016-06-01

    Electrorheological fluids offer potential for developing rapidly actuated hydraulic devices where shear forces or pressure-driven flow are present. In this study, the Bingham yield stress of electrorheological fluids with different particle volume fractions is investigated experimentally in wall-driven and pressure-driven flow modes using measurements in a parallel-plate rheometer and a microfluidic channel, respectively. A modified Krieger-Dougherty model can be used to describe the effects of the particle volume fraction on the yield stress and is in good agreement with the viscometric data. However, significant yield hardening in pressure-driven channel flow is observed and attributed to an increase and eventual saturation of the particle volume fraction in the channel. A phenomenological physical model linking the densification and consequent microstructure to the ratio of the particle aggregation time scale compared to the convective time scale is presented and used to predict the enhancement in yield stress in channel flow, enabling us to reconcile discrepancies in the literature between wall-driven and pressure-driven flows.

  13. Superconducting (radiation hardened) magnets for mirror fusion devices

    SciTech Connect

    Henning, C.D.; Dalder, E.N.C.; Miller, J.R.; Perkins, J.R.

    1983-12-07

    Superconducting magnets for mirror fusion have evolved considerably since the Baseball II magnet in 1970. Recently, the Mirror Fusion Test Facility (MFTF-B) yin-yang has been tested to a full field of 7.7 T with radial dimensions representative of a full scale reactor. Now the emphasis has turned to the manufacture of very high field solenoids (choke coils) that are placed between the tandem mirror central cell and the yin-yang anchor-plug set. For MFTF-B the choke coil field reaches 12 T, while in future devices like the MFTF-Upgrade, Fusion Power Demonstration and Mirror Advanced Reactor Study (MARS) reactor the fields are doubled. Besides developing high fields, the magnets must be radiation hardened. Otherwise, thick neutron shields increase the magnet size to an unacceptable weight and cost. Neutron fluences in superconducting magnets must be increased by an order of magnitude or more. Insulators must withstand 10/sup 10/ to 10/sup 11/ rads, while magnet stability must be retained after the copper has been exposed to fluence above 10/sup 19/ neutrons/cm/sup 2/.

  14. Hardening by bubbles in He-implanted Ni

    SciTech Connect

    Knapp, J. A.; Follstaedt, D. M.; Myers, S. M.

    2008-01-01

    Detailed finite-element modeling of nanoindentation data is used to obtain the mechanical properties of Ni implanted with 1-10 at. % He. The mechanical properties of this material elucidate the fundamental materials science of dislocation pinning by nanometer-size gas bubbles and also have implications for radiation damage of materials. Cross-section transmission electron microscopy showed that implantation of 1-5 at. % He at room temperature or at 200 deg. C produced a highly damaged layer extending to a depth of 700-800 nm and containing a fine dispersion of He bubbles with diameters of 1.1{+-}0.2 nm. Implantation at 500 deg. C enlarged the bubble sizes. By fitting the nanoindentation data with a finite-element model that includes the responses of both the implanted layer and the unimplanted substrate in the deformation, the Ni(He) layers are shown to have hardnesses as much as approximately seven times that of untreated Ni, up to 8.3{+-}0.6 GPa. Examination of the dependence of yield strength on He concentration, bubble size, and bubble density reveals that an Orowan hardening mechanism is likely to be in operation, indicating that the bubbles pin dislocation motion as strongly as hard second-phase precipitates do. This strong pinning of dislocations by bubbles is also supported by our numerical simulations, which show that substantial applied shear stress is required to move a dislocation through an empty cavity.

  15. Switchable hardening of a ferromagnet at fixed temperature

    PubMed Central

    Silevitch, D. M.; Aeppli, G.; Rosenbaum, T. F.

    2010-01-01

    The intended use of a magnetic material, from information storage to power conversion, depends crucially on its domain structure, traditionally crafted during materials synthesis. By contrast, we show that an external magnetic field, applied transverse to the preferred magnetization of a model disordered uniaxial ferromagnet, is an isothermal regulator of domain pinning. At elevated temperatures, near the transition into the paramagnet, modest transverse fields increase the pinning, stabilize the domain structure, and harden the magnet, until a point where the field induces quantum tunneling of the domain walls and softens the magnet. At low temperatures, tunneling completely dominates the domain dynamics and provides an interpretation of the quantum phase transition in highly disordered magnets as a localization/delocalization transition for domain walls. While the energy scales of the rare earth ferromagnet studied here restrict the effects to cryogenic temperatures, the principles discovered are general and should be applicable to existing classes of highly anisotropic ferromagnets with ordering at room temperature or above. PMID:20133728

  16. Magnetic hardening of Fe30Co70 nanowires

    NASA Astrophysics Data System (ADS)

    Liébana Viñas, Sara; Salikhov, Ruslan; Bran, Cristina; Palmero, Ester M.; Vazquez, Manuel; Arvan, Behnaz; Yao, Xiang; Toson, Peter; Fidler, Josef; Spasova, Marina; Wiedwald, Ulf; Farle, Michael

    2015-10-01

    3d transition metal-based magnetic nanowires (NWs) are currently considered as potential candidates for alternative rare-earth-free alloys as novel permanent magnets. Here, we report on the magnetic hardening of Fe30Co70 nanowires in anodic aluminium oxide templates with diameters of 20 nm and 40 nm (length 6 μm and 7.5 μm, respectively) by means of magnetic pinning at the tips of the NWs. We observe that a 3-4 nm naturally formed ferrimagnetic FeCo oxide layer covering the tip of the FeCo NW increases the coercive field by 20%, indicating that domain wall nucleation starts at the tip of the magnetic NW. Ferromagnetic resonance (FMR) measurements were used to quantify the magnetic uniaxial anisotropy energy of the samples. Micromagnetic simulations support our experimental findings, showing that the increase of the coercive field can be achieved by controlling domain wall nucleation using magnetic materials with antiferromagnetic exchange coupling, i.e. antiferromagnets or ferrimagnets, as a capping layer at the nanowire tips.

  17. Stress corrosion cracking evaluation of martensitic precipitation hardening stainless steels

    NASA Technical Reports Server (NTRS)

    Humphries, T. S.; Nelson, E. E.

    1980-01-01

    The resistance of the martensitic precipitation hardening stainless steels PH13-8Mo, 15-5PH, and 17-4PH to stress corrosion cracking was investigated. Round tensile and c-ring type specimens taken from several heats of the three alloys were stressed up to 100 percent of their yield strengths and exposed to alternate immersion in salt water, to salt spray, and to a seacoast environment. The results indicate that 15-5PH is highly resistant to stress corrosion cracking in conditions H1000 and H1050 and is moderately resistant in condition H900. The stress corrosion cracking resistance of PH13-8Mo and 17-4PH stainless steels in conditions H1000 and H1050 was sensitive to mill heats and ranged from low to high among the several heats included in the tests. Based on a comparison with data from seacoast environmental tests, it is apparent that alternate immersion in 3.5 percent salt water is not a suitable medium for accelerated stress corrosion testing of these pH stainless steels.

  18. A Radiation Hardened by Design CMOS ASIC for Thermopile Readouts

    NASA Technical Reports Server (NTRS)

    Quilligan, G.; Aslam, S.; DuMonthier, J.

    2012-01-01

    A radiation hardened by design (RHBD) mixed-signal application specific integrated circuit (ASIC) has been designed for a thermopile readout for operation in the harsh Jovian orbital environment. The multi-channel digitizer (MCD) ASIC includes 18 low noise amplifier channels which have tunable gain/filtering coefficients, a 16-bit sigma-delta analog-digital converter (SDADC) and an on-chip controller. The 18 channels, SDADC and controller were designed to operate with immunity to single event latchup (SEL) and to at least 10 Mrad total ionizing dose (TID). The ASIC also contains a radiation tolerant 16-bit 20 MHz Nyquist ADC for general purpose instrumentation digitizer needs. The ASIC is currently undergoing fabrication in a commercial 180 nm CMOS process. Although this ASIC was designed specifically for the harsh radiation environment of the NASA led JEO mission it is suitable for integration into instrumentation payloads 011 the ESA JUICE mission where the radiation hardness requirements are slightly less stringent.

  19. Strain hardening mechanisms in a Ni-Mo-Cr alloy

    SciTech Connect

    Dymek, S. ); Dollar, M. ); Klarstrom, D.L. )

    1991-01-01

    HAYNES 242 alloy has been recently developed for gas turbine components applications. This age-hardenable alloy, consisting essentially of Ni-25%Mo-8%Cr, utilizes a long-range-ordering reaction to form uniformly sized and distributed, extremely small (on the order of 10nm), ordered particles. Excellent strength and ductility at elevated temperatures, low thermal expansion characteristics and good oxidation resistance of Haynes 242 alloy has encouraged a number of studies designed to characterize its properties. What is lacking is an attempt to understand the fundamentals of the deformation and strengthening mechanisms in this alloy. This on-going research has been undertaken to explore deformation mechanisms in unaged and aged Haynes 242 alloy. The emphasis has been put on the effects of initial precipitation structure on the development of deformation structure and how it controls selected mechanical properties. This paper presents selected results and reports a change in the deformation mode from crystallographic glide in an unaged alloy into twinning in the presence of ordered particles. Deformation twinning in Ni-Mo and Ni-Mo-Cr alloys was reported earlier but was not discussed in detail. This research sheds light on possible origins of particle-induced twinning in alloys strengthened by small ordered particles.

  20. 'Age-hardened alloy' based on bulk polycrystalline oxide ceramic

    NASA Astrophysics Data System (ADS)

    Gurnani, Luv; Singh, Mahesh Kumar; Bhargava, Parag; Mukhopadhyay, Amartya

    2015-05-01

    We report here for the first time the development of 'age-hardened/toughened' ceramic alloy based on MgO in the bulk polycrystalline form. This route allows for the facile development of a 'near-ideal' microstructure characterized by the presence of nanosized and uniformly dispersed second-phase particles (MgFe2O4) within the matrix grains, as well as along the matrix grain boundaries, in a controlled manner. Furthermore, the intragranular second-phase particles are rendered coherent with the matrix (MgO). Development of such microstructural features for two-phase bulk polycrystalline ceramics is extremely challenging following the powder metallurgical route usually adopted for the development of bulk ceramic nanocomposites. Furthermore, unlike for the case of ceramic nanocomposites, the route adopted here does not necessitate the usage of nano-powder, pressure/electric field-assisted sintering techniques and inert/reducing atmosphere. The as-developed bulk polycrystalline MgO-MgFe2O4 alloys possess considerably improved hardness (by ~52%) and indentation toughness (by ~35%), as compared to phase pure MgO.