Sample records for rapid cold hardening

  1. In vivo and in vitro rapid cold-hardening protects cells from cold-shock injury in the flesh fly

    Microsoft Academic Search

    Shu-Xia Yi; Richard E. Lee Jr

    2004-01-01

    The capacity to undergo rapid the cold-hardening response (RCH) has been documented in diverse groups of insects and functions to protect against non-freezing cold injury and to preserve physiological performance in response to environmental cooling. The RCH response is remarkable for the rapidity of its induction; however the mechanism by which insects perceive cold and transduce this input at the

  2. Anoxic stress and rapid cold hardening enhance cold tolerance of the migratory locust.

    PubMed

    Cui, Feng; Wang, Hongsheng; Zhang, Hanying; Kang, Le

    2014-10-01

    Anoxia and rapid cold hardening (RCH) can increase the cold tolerance of many animals. However, mechanisms underlying these two kinds of stresses remain unclear. In this study, we aimed to explore the relationship of acclimation to cold stress with acclimation to anoxic stress in the migratory locust, Locusta migratoria. RCH at 0°C for 3h promoted the survival of cold stress-exposed locusts. Anoxic hypercapnia (CO2 anoxic treatment) for 40 min exerted an effect similar to that of RCH. Anoxic hypercapnia within 1h can all promote the cold hardiness of locusts. We investigated the transcript levels of six heat shock protein (Hsp) genes, namely, Hsp20.5, Hsp20.6, Hsp20.7, Hsp40, Hsp70, and Hsp90. Four genes, namely, Hsp90, Hsp40, Hsp20.5, and Hsp20.7, showed differential responses to RCH and anoxic hypercapnia treatments. Under cold stress, locusts exposed to the two regimens showed different responses for Hsp90, Hsp20.5, and Hsp20.7. However, the varied responses disappeared after recovery from cold stress. Compared with the control group, the transcript levels of six Hsp genes were generally downregulated in locusts subjected to anoxic hypercapnia or/and RCH. These results indicate that anoxic stress and RCH have different mechanisms of regulating the transcription of Hsp family members even if the two treatments exerted similar effects on cold tolerance of the migratory locust. However, Hsps may not play a major role in the promotion of cold hardiness by the two treatments. PMID:25086202

  3. A specific glycerol kinase induces rapid cold hardening of the diamondback moth, Plutella xylostella.

    PubMed

    Park, Youngjin; Kim, Yonggyun

    2014-08-01

    Insects in temperate zones survive low temperatures by migrating or tolerating the cold. The diamondback moth, Plutella xylostella, is a serious insect pest on cabbage and other cruciferous crops worldwide. We showed that P. xylostella became cold-tolerant by expressing rapid cold hardiness (RCH) in response to a brief exposure to moderately low temperature (4°C) for 7h along with glycerol accumulation in hemolymph. Glycerol played a crucial role in the cold-hardening process because exogenously supplying glycerol significantly increased the cold tolerance of P. xylostella larvae without cold acclimation. To determine the genetic factor(s) responsible for RCH and the increase of glycerol, four glycerol kinases (GKs), and glycerol-3-phosphate dehydrogenase (PxGPDH) were predicted from the whole P. xylostella genome and analyzed for their function associated with glycerol biosynthesis. All predicted genes were expressed, but differed in their expression during different developmental stages and in different tissues. Expression of the predicted genes was individually suppressed by RNA interference (RNAi) using double-stranded RNAs specific to target genes. RNAi of PxGPDH expression significantly suppressed RCH and glycerol accumulation. Only PxGK1 among the four GKs was responsible for RCH and glycerol accumulation. Furthermore, PxGK1 expression was significantly enhanced during RCH. These results indicate that a specific GK, the terminal enzyme to produce glycerol, is specifically inducible during RCH to accumulate the main cryoprotectant. PMID:24973793

  4. Low temperature acclimated populations of the grain aphid Sitobion avenae retain ability to rapidly cold harden with enhanced fitness.

    PubMed

    Powell, S J; Bale, J S

    2005-07-01

    In contrast to previous studies of rapid cold-hardening (RCH), which have investigated the responses of insects maintained under 'summer conditions' (20 degrees to 25 degrees C), this study focuses on the ability of low-temperature acclimated insects to undergo RCH. When the grain aphid Sitobion avenae Fabricus was low-temperature acclimated by rearing for three generations at 10 degrees C, the discriminating temperatures (temperature that results in approximately 20% survival after direct transfer from the rearing temperature to a sub-zero temperature for a period of 3 h), of first instar nymphs and adult aphids were -11.5 degrees and -12 degrees C, respectively. Maximum rapid cold-hardening was induced by cooling aphids at 0 degrees C for 2 h (nymphs) or 30 min (adults), resulting in survival at the respective discriminating temperatures increasing from 26% to 96% (nymphs) and 22% to 70% (adults). Cooling from 10 degrees to 0 degrees C at 1 degree, 0.1 degrees and 0.05 degrees C min-1 significantly increased survival of nymphs at the discriminating temperature, but not of adults. There were no ;ecological costs' associated with rapid cold-hardening at 0 degrees C, or with exposure of rapidly cold-hardened aphids to the discriminating temperatures; fecundity and longevity, in both nymphs and adults were either similar to control aphids or significantly increased. The study demonstrates that rapid cold-hardening ability is retained in aphids that have already undergone cold-acclimation, as would be the case in overwintering aphids. Both rapid cold-hardening and subsequent exposure at previously lethal temperatures can enhance fitness in surviving individuals. PMID:15961747

  5. Rapid cold-hardening blocks cold-induced apoptosis by inhibiting the activation of pro-caspases in the flesh fly Sarcophaga crassipalpis

    Microsoft Academic Search

    Shu-Xia YiRichard; Richard E. Lee

    2011-01-01

    Apoptosis plays important roles in the selective elimination of sub-lethally damaged cells due to various environmental stresses.\\u000a The rapid cold-hardening (RCH) response protects insects from the otherwise lethal consequences of injury due to cold-shock.\\u000a We recently demonstrated that cold shock induces apoptotic cell death in insects and that RCH functions to specifically block\\u000a cold-shock-induced apoptosis. In the present study we

  6. A Rapid Cold-Hardening Process in Insects Richard E. Lee; Cheng-ping Chen; David L. Denlinger

    E-print Network

    Lee Jr., Richard E.

    of the leader peptide remains in the cytoplasm during the mem- brane-insertion process in vivo. An alterna- tiveA Rapid Cold-Hardening Process in Insects Richard E. Lee; Cheng-ping Chen; David L. Denlinger the membrane, and not process- ing, is the rate-limiting step for coat produc- tion. The coat protein, however

  7. Pre-adapted to the maritime Antarctic?--rapid cold hardening of the midge, Eretmoptera murphyi.

    PubMed

    Everatt, M J; Worland, M R; Bale, J S; Convey, P; Hayward, S A L

    2012-08-01

    During the 1960s, the midge, Eretmoptera murphyi, was transferred from sub-Antarctic South Georgia (55°S 37°W) where it is endemic to a single location on maritime Antarctic Signy Island (60°S 45°W). Its distribution has since expanded considerably, suggesting that it is pre-adapted to the more severe conditions further south. To test one aspect of the level of its pre-adaptation, the rapid cold hardening (RCH) response in this species was investigated. When juvenile (L1-L2) and mature (L3-L4) larvae of E. murphyi were directly exposed to progressively lower temperatures for 8h, they exhibited Discriminating Temperatures (DTemp, temperature at which there is 10-20% survival of exposed individuals) of -11.5 and -12.5°C, respectively. The mean SCP was above -7.5°C in both larval groups, confirming the finding of previous studies that this species is freeze-tolerant. Following gradual cooling (0.2°Cmin(-1)), survival was significantly greater at the DTemp in both larval groups. The response was strong, lowering the lower lethal temperature (LLT) by up to 6.5°C and maintaining survival above 80% for at least 22h at the DTemp. RCH was also exhibited during the cooling phase of an ecologically relevant thermoperiodic cycle (+4°C to -3°C). Mechanistically, the response did not affect freezing, with no alteration in the supercooling point (SCP) found following gradual cooling, and was not induced while the organism was in a frozen state. These results are discussed in light of E. murphyi's pre-adaptation to conditions on Signy Island and its potential to colonize regions further south in the maritime Antarctic. PMID:22684111

  8. Shifts in the carbohydrate, polyol, and amino acid pools during rapid cold-hardening and diapause-associated cold-hardening in flesh flies ( Sarcophaga crassipalpis ): a metabolomic comparison

    Microsoft Academic Search

    M. Robert Michaud; David L. Denlinger

    2007-01-01

    Flesh flies can enhance their cold hardiness by entering a photoperiod-induced pupal diapause or by a temperature-induced\\u000a rapid cold-hardening process. To determine whether the same or different metabolites are involved in these two responses,\\u000a derivatized polar extracts from flesh flies subjected to these treatments were examined using gas chromatography–mass spectrophotometry\\u000a (GC–MS). This metabolomic approach demonstrated that levels of metabolites involved

  9. Rapid cold-hardening blocks cold-induced apoptosis by inhibiting the activation of pro-caspases in the flesh fly Sarcophaga crassipalpis.

    PubMed

    Yi, Shu-Xia; Lee, Richard E

    2011-03-01

    Apoptosis plays important roles in the selective elimination of sub-lethally damaged cells due to various environmental stresses. The rapid cold-hardening (RCH) response protects insects from the otherwise lethal consequences of injury due to cold-shock. We recently demonstrated that cold shock induces apoptotic cell death in insects and that RCH functions to specifically block cold-shock-induced apoptosis. In the present study we used isolated fat body, midgut, muscle, and Malpighian tubules from adult flesh flies Sarcophaga crassipalpis to test the following hypotheses: (1) cold-induced apoptosis varies among different tissues and (2) RCH blocks the apoptotic pathway by preventing the activation of pro-caspases. Cold-shock induced substantial amounts of apoptotic cell death that matched with tissue damage as determined using vital dyes. RCH treatment significantly reduced apoptotic cell death in all tested tissues. Caspase-3 (executioner) activity was 2-3 times higher in the cold- and heat-shocked groups than in control and RCH groups. Likewise, the activity of caspase-9 (initiator) showed a similar trend as for caspase-3 in all tissues but midgut. In addition, cold-shock and heat-shock treatments also increased caspase-2 activity 2-3 folds in both soluble and membrane fractions of fat body and muscle extracts compared to controls. PMID:21197578

  10. The protective effect of rapid cold-hardening develops more quickly in frozen versus supercooled larvae of the Antarctic midge, Belgica antarctica.

    PubMed

    Kawarasaki, Yuta; Teets, Nicholas M; Denlinger, David L; Lee, Richard E

    2013-10-15

    During the austral summer, larvae of the terrestrial midge Belgica antarctica (Diptera: Chironomidae) experience highly variable and often unpredictable thermal conditions. In addition to remaining freeze tolerant year-round, larvae are capable of swiftly increasing their cold tolerance through the rapid cold-hardening (RCH) response. The present study compared the induction of RCH in frozen versus supercooled larvae. At the same induction temperature, RCH occurred more rapidly and conferred a greater level of cryoprotection in frozen versus supercooled larvae. Furthermore, RCH in frozen larvae could be induced at temperatures as low as -12°C, which is the lowest temperature reported to induce RCH. Remarkably, as little as 15 min at -5°C significantly enhanced larval cold tolerance. Not only is protection from RCH acquired swiftly, but it is also quickly lost after thawing for 2 h at 2°C. Because the primary difference between frozen and supercooled larvae is cellular dehydration caused by freeze concentration of body fluids, we also compared the effects of acclimation in dehydrated versus frozen larvae. Because slow dehydration without chilling significantly increased larval survival to a subsequent cold exposure, we hypothesize that cellular dehydration caused by freeze concentration promotes the rapid acquisition of cold tolerance in frozen larvae. PMID:23868837

  11. The limits of drought-induced rapid cold-hardening: extremely brief, mild desiccation triggers enhanced freeze-tolerance in Eurosta solidaginis larvae.

    PubMed

    Gantz, J D; Lee, Richard E

    2015-02-01

    Rapid cold-hardening (RCH) is a highly conserved response in insects that induces physiological changes within minutes to hours of exposure to low temperature and provides protection from chilling injury. Recently, a similar response, termed drought-induced RCH, was described following as little as 6h of desiccation, producing a loss of less than 10% of fresh mass. In this study, we investigated the limits and mechanisms of this response in larvae of the goldenrod gall fly Eurosta solidaginis (Diptera, Tephritidae). The cold-hardiness of larvae increased markedly after as few as 2h of desiccation and a loss of less than 1% fresh mass, as organismal survival increased from 8% to 41% following exposure to -18 °C. Tissue-level effects of desiccation were observed within 1h, as 87% of midgut cells from desiccated larvae remained viable following freezing compared to 57% of controls. We also demonstrated that drought-induced RCH occurs independently of neuroendocrine input, as midgut tissue desiccated ex vivo displayed improved freeze-tolerance relative to control tissue (78-11% survival, respectively). Finally, though there was an increase in hemolymph osmolality beyond the expected effects of the osmo-concentration of solutes during dehydration, we determined that this increase was not due to the synthesis of glycerol, glucose, sorbitol, or trehalose. Our results indicate that E. solidaginis larvae are extremely sensitive to desiccation, which is a triggering mechanism for one or more physiological pathways that confer enhanced freeze-tolerance. PMID:25545423

  12. Spatial Conditioning in the Flesh Fly, Sarcophaga crassipal pis: Disruption of Learning by Cold Shock and Protection by Rapid Cold Hardening

    Microsoft Academic Search

    Young-Soo Kim; D. L. Denlinger; B. Smith

    2005-01-01

    We have developed a new paradigm for examining classical conditioning in the flesh fly, Sarcophaga crassipalpis, and specifically apply it as a sensitive measurement for sublethal effects of cold shock. When water was applied as a conditioned stimulus to the right tarsus and reinforced with a brief opportunity to feed on a sucrose-water solution, flies quickly learn to discriminate stimulation

  13. Low-temperature tolerance and cold hardening of cacti

    SciTech Connect

    Nobel, P.S.

    1982-12-01

    Reduced uptake by the chlorenchyma cells of cacti of a stain (neutral red) was used as an indicator of low-temperature damage resulting from cooling stems in the laboratory. Necrosis set in a few degrees below the temperature at which the fraction of cells accumulating stain was reduced by 50%. Coryphantha vivipara, Opuntia polyacantha, and Pediocactus simpsonii, which range to over 300 m altitude in southern Wyoming, were quite cold tolerant. Relationships among tissue cold sensitivity, morphological features which protect the stems from low temperatures, and the occurrence of species in progressively colder regions were investigated. Differences in tissue cold sensitivity accounted for the approx. = 600 m higher elevational limit of Coryphantha vivipara var. rosea compared to the morphologically similar var. deserti in southern Nevada. In contrast, morphological differences alone could adequately explain the relative northern limits of the columnar cacti Carnegiea gigantea vs Stenocereus gummosus and the barrel cacti Ferocactus acanthodes vs. F. wislizenii in the southwestern United States, as previously indicated using a computer model. Cold hardening in response to decreasing day/night air temperatures was observed for 10 species. A decrease from 50/sup 0//40/sup 0/ to 10/sup 0//0/sup 0/ lowered by 4/sup 0/ the temperature at which the fraction of the chlorenchyma cells taking up stain was reduced 50% for both D. rhodacantha and T. candicans, with a half-time for the shift of approx. = 3 d. The tolerance of subzero temperatures and the ability to cold harden allow cacti to range into regions with considerable wintertime freezing.

  14. Low temperature tolerance and cold hardening of cacti

    SciTech Connect

    Nobel, P.S.

    1982-12-01

    Reduced uptake by the chlorenchyma cells of cacti of a stain (neutral red) was used as an indicator of low-temperature damage resulting from cooling stems in the laboratory. Necrosis set in a few degrees below the temperature at which the fraction of cells accumulating stain was reduced by 50%. Coryphantha vivipara, Opuntia polyacantha, and Pediocactus simpsonii, which range to over 3000 m altitude in southern Wyoming, were quite cold tolerant (50% inhibition of staining occurred from -17/sup 0/ to -20/sup 0/C), while O. bigelovii and O. ramosissima, which are restricted to much warmer habitats, were not very cold tolerant (50% inhibition from -4/sup 0/ to -7/sup 0/). Relationships among tissue cold sensitivity, morphological features which protect the stems from low temperatures, and the occurrence of species in progressively colder regions were investigated. Differences in tissue cold sensitivity accounted for the =600 m higher elevational limit of Coryphantha vivipara var. rosea compared to the morphologically similar var. deserti in southern Nevada. In contrast, morphological differences alone could adequately explain the relative northern limits of the columnar cacti Carnegiea gigantea vs. Stenocereus gummosus and the barrel cacti Ferocactus acanthodes vs. F. wislizenii in the southwestern United States, as previously indicated using a computer model. Differences in both morphology and tissue cold sensitivity apparently influenced the relative northern ranges of Lophocereus schottii with respect to the other columnar cacti and F. covillei with respect to the other barrel cacti, as well as the relative elevational range of Denmoza rhodacantha with respect to Trichocereus candicans in northcentral Argentina. Cold hardening in response to decreasing day/night air temperatures was observed for 10 species.

  15. Rapid magnetic hardening by rapid thermal annealing in NdFeB-based nanocomposites

    Microsoft Academic Search

    Kung-Te Chu; Z Q Jin; Vamsi M Chakka; J P Liu

    2005-01-01

    A systematic study of heat treatments and magnetic hardening of NdFeB-based melt-spun nanocomposite ribbons have been carried out. Comparison was made between samples treated by rapid thermal annealing and by conventional furnace annealing. Heating rates up to 200 K s?1 were adopted in the rapid thermal processing. It was observed that magnetic hardening can be realized in an annealing time

  16. Rapid magnetic hardening by rapid thermal annealing in NdFeB-based nanocomposites

    Microsoft Academic Search

    Kung-Te Chu; Z. Q. Jin; Vamsi M. Chakka; J. P. Liu

    2005-01-01

    A systematic study of heat treatments and magnetic hardening of NdFeB-based melt-spun nanocomposite ribbons have been carried out. Comparison was made between samples treated by rapid thermal annealing and by conventional furnace annealing. Heating rates up to 200 K s-1 were adopted in the rapid thermal processing. It was observed that magnetic hardening can be realized in an annealing time

  17. Rapid magnetic hardening by rapid thermal annealing in NdFeB-based nanocomposites

    NASA Astrophysics Data System (ADS)

    Chu, Kung-Te; Jin, Z. Q.; Chakka, Vamsi M.; Liu, J. P.

    2005-11-01

    A systematic study of heat treatments and magnetic hardening of NdFeB-based melt-spun nanocomposite ribbons have been carried out. Comparison was made between samples treated by rapid thermal annealing and by conventional furnace annealing. Heating rates up to 200 K s-1 were adopted in the rapid thermal processing. It was observed that magnetic hardening can be realized in an annealing time as short as 1 s. Coercivity of 10.2 kOe in the nanocomposites has been obtained by rapid thermal annealing for 1 s, and prolonged annealing did not give any increase in coercivity. Detailed results on the effects of annealing time, temperature and heating rate have been obtained. The dependence of magnetic properties on the annealing parameters has been investigated. Structural characterization revealed that there is a close correlation between magnetic hardening and nanostructured morphology. The coercivity mechanism was also studied by analysing the magnetization minor loops.

  18. Strain hardening of heavily cold-worked metals

    SciTech Connect

    Hecker, S.S.; Stout, M.G.

    1982-01-01

    It is demonstrated that strain hardening in torsion cannot be correlated with axisymmetric deformation by the von Mises effective stress strain criterion. In fcc materials, the flow stress levels and strain hardening rates are typically lower in torsion and saturation, only at lower stress levels. In bcc iron, a low saturtion stress is observed for torsion, whereas linear hardening is observed for axisymmetric extension. Much of the discrepancy in flow curves can be explained by texture. It is demonstrated that a crystallographic effective stress-strain criterion based on evolving average Taylor factors provides the proper magnitude correction for torsional flow curves in fcc materials. The simple crystallographic analysis does not fully explain the hardening response following deformation path changes and multidirectional loading. 96 references, 42 figures.

  19. Changes in Hechtian Strands in Cold-Hardened Cells Measured by Optical Microsurgery1

    E-print Network

    Swartzlander Jr., Grover A.

    for mitochon- dria and ER in animal cells (Terasaki and Reese, 1992). Staehelin (1997) reviewed the functionalChanges in Hechtian Strands in Cold-Hardened Cells Measured by Optical Microsurgery1 Charles S of Hechtian strands in tobacco (Nicoti- ana tabacum) and Ginkgo biloba callus cells. Using optical twee- zers

  20. Apoplastic Sugars, Fructans, Fructan Exohydrolase, and Invertase in Winter Oat: Responses to Second-Phase Cold Hardening

    Microsoft Academic Search

    David P. Livingston III; Cynthia A. Henson

    1998-01-01

    Changes in apoplastic carbohydrate concentrations and activities of carbohydrate-degrading enzymes were determined in crown tis- sues of oat (Avena sativa L., cv Wintok) during cold hardening. During second-phase hardening (23°C for 3 d) levels of fructan, sucrose, glucose, and fructose in the apoplast increased significantly above that in nonhardened and first-phase-hardened plants. The extent of the increase in apoplastic fructan

  1. Distortion Analysis in the Manufacturing of Cold-Drawn and Induction-Hardened Components

    NASA Astrophysics Data System (ADS)

    Hirsch, Thomas Georg Karl; da Silva Rocha, Alexandre; Menezes Nunes, Rafael

    2013-12-01

    In this investigation, a design of experiments analysis of distortion for a typical manufacturing process involving pre-straightening, cold drawing, and induction hardening of AISI 1045 cylindrical steel bars was carried out. A careful characterization of the material, including residual stress states and geometrical changes, was done for the different manufacturing steps. In order to identify effects and correlations on distortion behavior, the investigated variables included the batch influence, the combined drawing process itself with two different drawing angles and two different polishing and straightening (P.S.) angles, a stress relief treatment which was applied to a part of the samples, and finally induction hardening with two different surface hardening depths. Main and statistically significant effects on the distortion of the induction-hardened samples were found to be in this order: first, the interaction between the drawing angle and batch, then the interaction between drawing angles, and finally drawing angle and induction hardened layer. It was also found that the distortion potentials are transmitted from the drawing process to further manufacturing steps and, consequently, from one production site to the next.

  2. Characterizing Hardening on Annealing of Cold-Rolled Aluminum AA3103 Strips

    NASA Astrophysics Data System (ADS)

    Govindaraj, Nagaraj Vinayagam; Bjørge, Ruben; Holmedal, Bjørn

    2013-10-01

    AA3103 aluminum strips were cold rolled to various von Mises strains up to 4.7. In addition, two severely deformed conditions were obtained by one and four cycles of cold accumulated roll bonding subsequent to cold rolling to a strain of 4.2. For cases of subsequent annealing at 498 K (225 °C) for 10 minutes, an increase in the ultimate tensile strength was observed at the rolling strains of 1.7 and higher. Similar hardening is observed for a wide range of temperature-time combinations for temperatures greater than 423 K (150 °C). The yield stress is also increased by a few per cent during further cold rolling. The magnitude of the increase in strength on annealing increased with the increasing strain. Electron backscattered diffraction and transmission electron microscopy studies showed no significant changes in the high- or low-angle grain boundary spacings by this annealing. A systematic investigation on the roles played by Si and Mn was made with different homogenization treatments of AA3103 and of an AlSi alloy. Based on tensile tests, and differential scanning calorimetry and electrical conductivity measurements, it is concluded that Mn plays a major role. The exact mechanisms causing hardening on annealing are not identified, but through elimination of other explanations, it is suggested that some sort of clustering or precipitation mechanism is involved.

  3. Effect of auxin physiological analogues on rapeseed (Brassica napus) cold hardening, seed yield and quality.

    PubMed

    Gavelien?, Virgilija; Novickien?, Leonida; Pakalniškyt?, Lina

    2013-03-01

    The effect of the auxin physiological analogues analogues 1-[2-chloroethoxycarbonylmethyl]-4-naphthalenesulfonic acid calcium salt (TA-12) and 1-[2-dimethylaminoethoxicarbonylmethyl]naphthalene chlormethylate (TA-14) TA-14 on different winter rapeseed cultivars were studied with regard to their autumnal growth, cold hardening, accumulation of the stress-protective metabolites proline and saccharide in plant organs: apical bud and root collum, winter survival and productivity formation. The test cultivars were the very early 'Libea' medium-resistant to wintering, the medium-early 'Sunday' resistant to wintering, the medium-early 'Valesca' less than medium resistant to wintering, and the early 'Hornet' (hybrid) tolerant to stress growth conditions. During the period of cold hardening in natural field conditions, the test compounds TA-12 (2 mM) and TA-14 (4 mM), applied to different winter rapeseed cultivars at the 4th-5th leaf stage, stimulate accumulation proline and saccharides (sucrose and glucose) in the root collum and apical bud tissues, influence plants acclimation to cold, overwintering and productivity formation. Compounds TA-12 and especially TA-14 produced a stable effect on seed and crude fat yield in cvs. 'Hornet', 'Sunday' and 'Libea'. The genotypic peculiarities of a cultivar and the meteorological conditions of the plant vegetation period were the factors that mostly determined fatty acid content in seed oil. PMID:23086232

  4. Rapid hardening concrete for the construction of a small span bridge

    Microsoft Academic Search

    Stefano Cangiano; Alberto Meda; Giovanni A. Plizzari

    2009-01-01

    The interest in concrete having an early age strength is increased due to the possibility to limit the construction time. A rapid hardening concrete (RHC) can be applied in order to limit the interruption of heavy traffic ways, for the construction of infrastructures such as bridges, viaducts, etc.In this paper, a practical case of using RHC is presented. The deck

  5. Mechanism of Secondary Hardening in Rapid Tempering of Dual-Phase Steel

    NASA Astrophysics Data System (ADS)

    Saha, Dulal Chandra; Nayak, Sashank S.; Biro, Elliot; Gerlich, Adrian P.; Zhou, Y.

    2014-12-01

    Dual-phase steel with ferrite-martensite-bainite microstructure exhibited secondary hardening in the subcritical heat affected zone during fiber laser welding. Rapid isothermal tempering conducted in a Gleeble simulator also indicated occurrence of secondary hardening at 773 K (500 °C), as confirmed by plotting the tempered hardness against the Holloman-Jaffe parameter. Isothermally tempered specimens were characterized by analytic transmission electron microscopy and high-angle annular dark-field imaging. The cementite (Fe3C) and TiC located in the bainite phase of DP steel decomposed upon rapid tempering to form needle-shaped Mo2C (aspect ratio ranging from 10 to 25) and plate-shaped M4C3 carbides giving rise to secondary hardening. Precipitation of these thermodynamically stable and coherent carbides promoted the hardening phenomenon. However, complex carbides were only seen in the tempered bainite and were not detected in the tempered martensite. The martensite phase decomposed into ferrite and spherical Fe3C, and interlath-retained austenite decomposed into ferrite and elongated carbide.

  6. Finite Element Calculation of Residual Stress and Cold-work Hardening Induced in Inconel 718 by Low Plasticity Burnishing

    Microsoft Academic Search

    Feng-Lei Li; Wei Xia; Zhao-Yao Zhou

    2010-01-01

    Low Plasticity Burnishing (LPB), a mechanical surface enhancement technology was developed to produce a deep layer of highly compressive residual stress comparable to laser shot peening, but with minimal cold-work hardening, LPB produces the most thermally stable compression to hot sections of gas turbine engines made by superalloy like Inconel 718. Literatures detailing the experimental effects of LPB are comprehensive,

  7. COLD-SHOCKINJURY AND RAPID COLD HARDENING IN THE FLESHFLY SARCOPHAGACRASSIPALPIS'

    E-print Network

    Lee Jr., Richard E.

    tissuefreezingatanystageof development (lre andDenlinger1985).TheSCpin both diapausingand nondiapausingpupae is around -23 C, but diapausingpupaeare 297 #12;298 C. CHEN, D. DENLINGER, AND R. LEE. JR ableto survivetemperaturesnearthe SCP only

  8. A new cold-induced alfalfa gene is associated with enhanced hardening at subzero temperature.

    PubMed Central

    Monroy, A F; Castonguay, Y; Laberge, S; Sarhan, F; Vezina, L P; Dhindsa, R S

    1993-01-01

    When alfalfa (Medicago sativa L. cv Apica) plants grown at room temperature are transferred to 2 degrees C, the temperature at which 50% of the plants fail to survive (LT50) decreases from -6 to -14 degrees C during the first 2 weeks but then increases to -9 degrees C during the subsequent 2 weeks. However, when plants are kept for 2 weeks at 2 degrees C and then transferred to -2 degrees C for another two weeks, the LT50 declines to -16 degrees C. These changes in freezing tolerance are paralleled by changes in transcript levels of cas15 (cold acclimation-specific gene encoding a 14.5-kD protein), a cold-induced gene. Cold-activation of cas15 occurs even when protein synthesis is inhibited by more than 90%, suggesting that cold-initiated events up to and including the accumulation of cas15 transcripts depend on preexisting gene products. cas15 shows little homology to any known gene at the nucleotide or amino acid level. The deduced polypeptide (CAS15) of 14.5 kD contains four repeats of a decapeptide motif and possesses a bipartite sequence domain at the carboxy terminus with homology to the reported nuclear-targeting signal sequences. Although the relative amount of cas15 DNA as a fraction of the total genomic DNA is similar in cultivars with different degrees of freezing tolerance, its organization in the genome is different. The possible role of cas15 in the development of cold-induced freezing tolerance is discussed. PMID:8278537

  9. Autumn growth and cold hardening of winter wheat under simulated climate change

    Microsoft Academic Search

    Hans M. Hanslin; Leiv M. Mortensen

    2010-01-01

    Plant responses to elevated CO2 are governed by temperature, and at low temperatures the beneficial effects of CO2 may be lost. To document the responses of winter cereals grown under cold conditions at northern latitudes, autumn growth of winter wheat exposed to ambient and elevated levels of temperature (+2.5°C), CO2 (+150 µmol mol), and shade (?30%) was studied in open-top

  10. Surface hardening of steel by boriding in a cold rf plasma

    NASA Technical Reports Server (NTRS)

    Finberg, I.; Avni, R.; Grill, A.; Spalvins, T.; Buckley, D. H.

    1985-01-01

    Scanning electron spectroscopy, X-ray diffractometry, Auger electron spectroscopy, and microhardness measurements, are used to study the surfaces of 4340-steel samples that have been borided in a cold RF plasma which had been initiated in a gas mixture of 2.7 percent diborane in Ar. As a result of the dislocation of the diborane in the plasma, boron is deposited on the surface of the steel substrate and two crystalline phases, tetragonal Fe2B and orthorhombic FeB, are formed. The formation of boride phases then increases the surface microhardness from 2650 MPa to a maximum value of 7740 MPa.

  11. Proteins Involved in Distinct Phases of Cold Hardening Process in Frost Resistant Winter Barley (Hordeum vulgare L.) cv Luxor

    PubMed Central

    Hlavá?ková, Iva; Vítámvás, Pavel; Šantr??ek, Ji?í; Kosová, Klára; Zelenková, Sylva; Prášil, Ilja Tom; Ovesná, Jaroslava; Hynek, Radovan; Kodí?ek, Milan

    2013-01-01

    Winter barley is an economically important cereal crop grown in higher latitudes and altitudes where low temperatures represent an important environmental constraint limiting crop productivity. In this study changes in proteome of leaves and crowns in a frost tolerant winter barley cv. Luxor in relation to short and long term periods of cold followed by a brief frost treatment were studied in order to disclose proteins responsible for the cold hardening process in distinct plant tissues. The mentioned changes have been monitored using two dimensional difference gel electrophoresis (2D-DIGE) with subsequent peptide-mapping protein identification. Regarding approximately 600–700 distinct protein spots detected on 2D gels, there has been found at least a two-fold change after exposure to low temperatures in about 10% of proteins in leaves and 13% of proteins in crowns. Protein and nitrogen metabolic processes have been influenced by low temperature to a similar extent in both tissues while catabolism, carbohydrate metabolism and proteins involved in stress response have been more affected in crowns than in leaves. The range of changes in protein abundance was generally higher in leaves and chloroplast proteins were frequently affected which suggests a priority to protect photosynthetic apparatus. Overall, our data proved existence of slightly different response strategies to low temperature stress in crowns and leaves, i.e., tissues with different biological role. Moreover, there have been found several proteins with large increase in accumulation, e.g., 33 kDa oxygen evolving protein of photosystem II in leaves and “enhanced disease susceptibility 1” in crowns; these proteins might have potential to indicate an enhanced level of frost tolerance in barley. PMID:23584021

  12. Microstructure characterization based on the type of deformed grains in cold-rolled, Cu-added, bake-hardenable steel

    SciTech Connect

    Kim, J.S. [Department of Printed Electronics Engineering, Sunchon National University, Suncheon, Jeonnam 540-742 (Korea, Republic of); Kim, S.I. [Technical Research Laboratories, POSCO, 699, Gumho-dong, Gwangyang-si, Jeonnam 545-090 (Korea, Republic of); Choi, S.-H., E-mail: shihoon@sunchon.ac.kr [Department of Printed Electronics Engineering, Sunchon National University, Suncheon, Jeonnam 540-742 (Korea, Republic of)

    2014-06-01

    The electron backscatter diffraction technique has been used to characterize the microstructure of deformed grains in cold-rolled, Cu-added, bake-hardenable steel. A new scheme based on the kind and number of average orientations, as determined from a unique grain map of the deformed grains, was developed in order to classify deformed grains by type. The ?-fiber components, ?-fiber components and random orientations, those which could not be assigned to either ?-fiber or ?-fiber components, were used to define the average orientation of unique grains within individual deformed grains. The microstructures of deformed grains in as-rolled specimens were analyzed based on the Taylor factor, stored energy, and misorientation. The relative levels and distributions of the Taylor factor, the stored energy and the misorientation were examined in terms of the types of deformed grains. - Highlights: • We characterized the microstructure of Cu-added BH steel using EBSD. • A new scheme was developed in order to classify deformed grains by type. • Stored energy and misorientation are strongly dependent on the type of deformed grains. • Microstructure was examined in terms of the types of deformed grains.

  13. Use of intraspecific variation in thermal responses for estimating an elevational cline in the timing of cold hardening in a sub-boreal conifer.

    PubMed

    Ishizuka, W; Ono, K; Hara, T; Goto, S

    2015-01-01

    To avoid winter frost damage, evergreen coniferous species develop cold hardiness with suitable phenology for the local climate regime. Along the elevational gradient, a genetic cline in autumn phenology is often recognised among coniferous populations, but further quantification of evolutionary adaptation related to the local environment and its responsible signals generating the phenological variation are poorly understood. We evaluated the timing of cold hardening among populations of Abies sachalinensis, based on time series freezing tests using trees derived from four seed source populations × three planting sites. Furthermore, we constructed a model to estimate the development of hardening from field temperatures and the intraspecific variations occurring during this process. An elevational cline was detected such that high-elevation populations developed cold hardiness earlier than low-elevation populations, representing significant genetic control. Because development occurred earlier at high-elevation planting sites, the genetic trend across elevation overlapped with the environmental trend. Based on the trade-off between later hardening to lengthen the active growth period and earlier hardening to avoid frost damage, this genetic cline would be adaptive to the local climate. Our modelling approach estimated intraspecific variation in two model components: the threshold temperature, which was the criterion for determining whether the trees accumulated the thermal value, and the chilling requirement for trees to achieve adequate cold hardiness. A higher threshold temperature and a lower chilling requirement could be responsible for the earlier phenology of the high-elevation population. These thermal responses may be one of the important factors driving the elevation-dependent adaptation of A. sachalinensis. PMID:24988996

  14. Microstructures, Mechanical Properties, and Strain Hardening Behavior of an Ultrahigh Strength Dual Phase Steel Developed by Intercritical Annealing of Cold-Rolled Ferrite/Martensite

    NASA Astrophysics Data System (ADS)

    Mazaheri, Y.; Kermanpur, A.; Najafizadeh, A.

    2015-07-01

    A dual phase (DP) steel was produced by a new process utilizing an uncommon cold-rolling and subsequent intercritical annealing of a martensite-ferrite duplex starting structure. Ultrafine grained DP steels with an average grain size of about 2 ?m and chain-networked martensite islands were achieved by short intercritical annealing of the 80 pct cold-rolled duplex microstructure. The strength of the low carbon steel with the new DP microstructure was reached about 1300 MPa (140 pct higher than that of the as-received state, e.g., 540 MPa), without loss of ductility. Tensile testing revealed good strength-elongation balance for the new DP steels (UTS × UE ? 11,000 to 15,000 MPa pct) in comparison with the previous works and commercially used high strength DP steels. Two strain hardening stages with comparable exponents were observed in the Holloman analysis of all DP steels. The variations of hardness, strength, elongation, and strain hardening behavior of the specimens with thermomechanical parameters were correlated to microstructural features.

  15. Effect of Cold Hardening on the Components of Respiratory Decarboxylation in the Light and in the Dark in Leaves of Winter Rye.

    PubMed Central

    Hurry, V.; Keerberg, O.; Parnik, T.; Oquist, G.; Gardestrom, P.

    1996-01-01

    In the dark, all decarboxylation reactions are associated with the oxidase reactions of mitochondrial electron transport. In the light, photorespiration is also active in photosynthetic cells. In winter rye (Secale cereale L.), cold hardening resulted in a 2-fold increase in the rate of dark respiratory CO2 release from leaves compared with nonhardened (NH) controls. However, in the light, NH and cold-hardened (CH) leaves had comparable rates of oxidase decarboxylation and total intracellular decarboxylation. Furthermore, whereas CH leaves showed similar rates of total oxidase decarboxylation in the dark and light, NH leaves showed a 2-fold increase in total oxidase activity in the light compared with the dark. Light suppressed oxidase decarboxylation of end products of photosynthesis 2-fold in NH leaves and 3-fold in CH leaves in air. However, in high-CO2, light did not suppress the oxidase decarboxylation of end products. Thus, the decrease in oxidase decarboxylation of end products observed in the light and in air reflected glycolate-cycle-related inhibition of tricarboxylic acid cycle activity. We also showed that the glycolate cycle was involved in the decarboxylation of the end products of photosynthesis in both NH and CH leaves, suggesting a flow of fixed carbon out of the starch pool in the light. PMID:12226322

  16. Rapid Growth Reduces Cold Resistance: Evidence from Latitudinal Variation in Growth Rate, Cold Resistance and Stress Proteins

    PubMed Central

    Stoks, Robby; De Block, Marjan

    2011-01-01

    Background Physiological costs of rapid growth may contribute to the observation that organisms typically grow at submaximal rates. Although, it has been hypothesized that faster growing individuals would do worse in dealing with suboptimal temperatures, this type of cost has never been explored empirically. Furthermore, the mechanistic basis of the physiological costs of rapid growth is largely unexplored. Methodology/Principal Finding Larvae of the damselfly Ischnura elegans from two univoltine northern and two multivoltine southern populations were reared at three temperatures and after emergence given a cold shock. Cold resistance, measured by chill coma recovery times in the adult stage, was lower in the southern populations. The faster larval growth rates in the southern populations contributed to this latitudinal pattern in cold resistance. In accordance with their assumed role in cold resistance, Hsp70 levels were lower in the southern populations, and faster growing larvae had lower Hsp70 levels. Yet, individual variation in Hsp70 levels did not explain variation in cold resistance. Conclusions/Significance We provide evidence for a novel cost of rapid growth: reduced cold resistance. Our results indicate that the reduced cold resistance in southern populations of animals that change voltinism along the latitudinal gradient may not entirely be explained by thermal selection per se but also by the costs of time constraint-induced higher growth rates. This also illustrates that stressors imposed in the larval stage may carry over and shape fitness in the adult stage and highlights the importance of physiological costs in the evolution of life-histories at macro-scales. PMID:21390210

  17. RAPID AND SENSITIVE FAME ANALYSIS OF BACTERIA BY COLD TRAP INJECTION GAS CHROMATOGRAPHY

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Fatty acid analysis is commonly used to identify bacteria. A cold trap is used to focus peaks at the head of the GC column. When combined with a rapid sample processing method that uses smaller volumes of solvents, it becomes possible to correctly identify bacteria from 1-2 mg of biomass....

  18. Structure and properties of dispersion-hardening spring alloy 36NKhTYuM8 after rapid quenching

    Microsoft Academic Search

    A. G. Rakhshtadt; O. M. Khovova; O. M. Zhigalina

    1996-01-01

    Austenitic dispersion-hardening alloy 36NKhTYuM8 is well known as a nonmagnetic corrosion-resistant and heat-resistant spring material having quite good technological ductility (after quenching) and a high yield strength after aging (a0002 = 930 – 950 N\\/mm2). It is used for the production of complicated and critical elastic members. There are data on the possibility of a certain improvement in the adaptability

  19. Rapid quenching studies of a commercial aluminium alloy 2014

    Microsoft Academic Search

    C. Suryanarayana; M. Hanumantha Rao

    1987-01-01

    Aluminium alloys can be strengthened by cold working, precipitation hardening and thermomechanical treatments leading to very high values of strength-toweight ratio. The advent of rapid solidification techniques in the 1960s has benefited the alloy development programmes further. It is now well established that rapid quenching of alloys, at cooling rates above 105 K sec ', leads to several metastable effects

  20. Ultra-rapid freezing by spraying/plunging: pre-cooling in the cold gaseous layer.

    PubMed

    Chang, Z H; Baust, J G

    1991-03-01

    A thermophysical model is established to analyse the influence of pre-cooling of a biological specimen in the cold gas layer associated with spray-freezing techniques. The basic principles governing the process of pre-cooling are provided. It is concluded that pre-cooling is one of the major limiting steps in attaining an overall ultra-rapid cooling rate. Pre-cooling has a substantial influence on the nature of the final frozen specimens. In order completely to avoid crystallization before entry into the liquid cryogen and maximize the overall cooling rate of the specimen, precautions should be taken to control the height of the gaseous layer and the size of the specimen. The probability of the specimen being frozen in the cold gaseous layer is reduced by increasing the entry speed. The effectiveness, however, becomes less marked at speeds greater than 10 m s. In order to minimize the risk of misinterpreting the measured cooling rate, it is necessary to specify the pre-cooling conditions. The pre-cooling effect is much more evident in liquid helium than in cryogens such as propane, ethane, Freon 12, 13 and 22. PMID:2046089

  1. 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.

  2. Stress State of 12% Ni Maraging Steel After a Modified Procedure of Precipitation Hardening

    Microsoft Academic Search

    J. Grum; M. Zupan?i?

    2009-01-01

    Fatigue resistance of a surface layer of dynamically and thermomechanically loaded machine components and tool parts can be improved with a combination of mechanical hardening by cold deformation and thermal precipitation hardening. One of the mechanical processes of surface hardening is a relatively simple and accessible process of roto peening. The hardening effect of roto peening is related to a

  3. Rapid cold-hardening in larvae of the Antarctic midge Belgica antarctica: cellular cold-sensing and a role for calcium

    E-print Network

    Lee Jr., Richard E.

    -Martinez,2 David L. Denlinger,2 and Richard E. Lee, Jr.1 1 Department of Zoology, Miami University, Oxford in final form 12 April 2008 Teets NM, Elnitsky MA, Benoit JB, Lopez-Martinez G, Denlinger DL, Lee RE, Jr

  4. Rapid Growth Reduces Cold Resistance: Evidence from Latitudinal Variation in Growth Rate, Cold Resistance and Stress Proteins

    Microsoft Academic Search

    Robby Stoks; Marjan de Block; Geoffrey Trussell

    2011-01-01

    BackgroundPhysiological costs of rapid growth may contribute to the observation that organisms typically grow at submaximal rates. Although, it has been hypothesized that faster growing individuals would do worse in dealing with suboptimal temperatures, this type of cost has never been explored empirically. Furthermore, the mechanistic basis of the physiological costs of rapid growth is largely unexplored.Methodology\\/Principal FindingLarvae of the

  5. Effects of a Short-Term Shift to Low Temperature and of Long-Term Cold Hardening on Photosynthesis and Ribulose-1,5-Bisphosphate Carboxylase/Oxygenase and Sucrose Phosphate Synthase Activity in Leaves of Winter Rye (Secale cereale L.).

    PubMed Central

    Hurry, V. M.; Malmberg, G.; Gardestrom, P.; Oquist, G.

    1994-01-01

    The effect of a short-term (hours) shift to low temperature (5[deg]C) and long-term (months) cold hardening on photosynthesis and carbon metabolism was studied in winter rye (Secale cereale L. cv Musketeer). Cold-hardened plants grown at 5[deg]C exhibited 25% higher in situ CO2 exchange rates than nonhardened plants grown at 24[deg]C. Cold-hardened plants maintained these high rates throughout the day, in contrast to nonhardened plants, which showed a gradual decline in photosynthesis after 3 h. Associated with the increase in photosynthetic capacity following cold hardening was an increase in ribulose-1,5-bisphosphate carboxylase/oxygenase and sucrose phosphate synthase activity and 3- to 4-fold increases in the pools of associated metabolites. Leaves of nonhardened plants shifted overnight to 5[deg]C required 9 h in the light at 5[deg]C before maximum rates of photosynthesis were reached. The gradual increase in photosynthesis in leaves shifted to 5[deg]C was correlated with a sharp decline in the 3-phosphoglycerate/triose phosphate ratio and by an increase in the ribulose bisphosphate/3-phosphoglycerate ratio, indicating the gradual easing of aninorganic phosphate-mediated feedback inhibition on photo-synthesis. We suggest that the strong recovery of photosynthesis in winter rye following cold hardening indicates that the buildup of photosynthetic enzymes, as well as those involved in sucrose synthesis, is an adaptive response that enables these plants to maximize the production of sugars that have both cryoprotective and storage functions that are critical to the performance of these cultivars during over-wintering. PMID:12232378

  6. The secondary hardening phenomenon in strain-hardened MP35N alloy

    SciTech Connect

    Asgari, S.; El-Danaf, E.; Shaji, E.; Kalidindi, S.R.; Doherty, R.D. [Drexel Univ., Philadelphia, PA (United States). Dept. of Materials Engineering] [Drexel Univ., Philadelphia, PA (United States). Dept. of Materials Engineering

    1998-10-09

    Mechanical testing and microscopy techniques were used to investigate the influence of aging on the structure and strengthening of MP35N alloy. It was confirmed that aging the deformed material at 600 C for 4 h provided additional strengthening, here referred to as secondary hardening, in addition to the primary strain hardening. The secondary hardening phenomenon was shown to be distinctly different from typical age hardening processes in that it only occurred in material deformed beyond a certain cold work level. At moderate strains, aging caused a shift in the entire stress-strain curve of the annealed material to higher stresses while at high strains, it produced shear localization and limited work softening. The secondary hardening increment was also found to be grain size dependent. The magnitude of the secondary hardening appeared to be controlled by the flow stress in the strain hardened material. A model is proposed to explain the observations and is supported by direct experimental evidence. The model is based on formation of h.c.p. nuclei through the Suzuki mechanism, that is segregation of solute atoms to stacking faults, on aging the strain hardened material. The h.c.p. precipitates appear to thicken only in the presence of high dislocation density produced by prior cold work.

  7. Long-Term Cold Acclimation Extends Survival Time at 0°C and Modifies the Metabolomic Profiles of the Larvae of the Fruit Fly Drosophila melanogaster

    Microsoft Academic Search

    Vladimír Kostál; Jaroslava Korbelová; Jan Rozsypal; Helena Zahradnícková; Jana Cimlová; Ales Tomcala; Petr Simek; Amit Singh

    2011-01-01

    BackgroundDrosophila melanogaster is a chill-susceptible insect. Previous studies on this fly focused on acute direct chilling injury during cold shock and showed that lower lethal temperature (LLT, approximately ?5°C) exhibits relatively low plasticity and that acclimations, both rapid cold hardening (RCH) and long-term cold acclimation, shift the LLT by only a few degrees at the maximum.Principal FindingsWe found that long-term

  8. The rapid assembly of synaptic sites in photoreceptor terminals of the fly's optic lobe recovering from cold shock.

    PubMed

    Brandstätter, J H; Meinertzhagen, I A

    1995-03-28

    When a housefly, Musca domestica, is subject to cold exposure (0 degrees C for 24 hr), a number of obvious changes are seen in the first optic neuropil, or lamina, beneath the compound eye. In particular, the number of afferent photoreceptor synapses declines by about 30%. This loss is dramatically restored after warm recovery at 23 degrees C for 24 hr. Synapses disappear at an average rate of 2-3/hr during cold exposure and reappear at a maximal rate of more than 20/hr during the first 2 hr of warm recovery. Thereafter their number temporarily overshoots control values, to increase at 6 hr of warm recovery to 60% above their cold-exposed minimum. The number subsequently returns more or less to normal. These changes demonstrate the lability of synaptic sites under these conditions, with individual sites forming and disappearing rapidly. The changes also interrupt the close correlation between synaptic number and the surface area of the receptor terminal, a correlation that normally conserves synaptic spacing density. The density is preserved during cold exposure but increases during warm recovery at a time when the addition of newly formed synapses exceeds the slower increase in receptor terminal size. PMID:7708704

  9. Rapid toluene mineralization by aquifer microorganisms at Adak, Alaska: Implications for intrinsic bioremediation in cold environments

    USGS Publications Warehouse

    Bradley, P.M.; Chapelle, F.H.

    1995-01-01

    Sediments from a relatively cold (5??C), petroleum hydrocarbon-contaminated aquifer in Adak, AK, mineralized [14C]toluene at an aerobic rate (16.3% day-1 at 5??C) comparable to that (5.1% day-1 at 20??C) of sediments from a more temperate aquifer at Hanahan, SC. In addition, rates of overall microbial metabolism in sediments from the two aquifers, as estimated by [1 -14C]acetate mineralization, were similar (???10.6% h-1) at their respective in situ temperatures. These results are not consistent with the common assumption that biodegradation rates in cold ground-water systems are depressed relative to more temperate systems. Furthermore, these results suggest that intrinsic bioremediation of petroleum hydrocarbon contaminants in cold groundwater systems may be technically feasible, in some cases.

  10. Rapid Quench Cold-Seal Apparatus with Computer-Controlled Pressure and Temperature Cycling

    Microsoft Academic Search

    A. Johnston; D. Senkovich

    2007-01-01

    We have constructed two computer-controlled, rapid quench, hydrothermal apparatuses that are ideal for experimentation on volcanological, geothermal, and ore deposit research problems. The devices can achieve maximum pressures of about 2 kbar and temperatures to 1100C, have the ability for experiments to be quenched very rapidly in a water-cooled environment, and are interfaced with computers which can control any regimen

  11. Case hardening of steel

    SciTech Connect

    Not Available

    1987-01-01

    The first chapter lays the groundwork for an understanding by covering absorption and diffusion of carbon, and the application of equilibrium data. Gas carburizing methods are presented, followed by other gaseous case hardening methods. Then, liquid case-hardening methods are discussed. Vacuum carburizing and pack carburizing are treated in a separate chapter. The second half of the volume deals with specific topics in relation to case hardening. First, heat-treatment considerations are presented, including chapters on cleaning and handling of parts, heat treatment, and furnaces and furnace parts and fixtures used in case hardening. The next chapter presents information on instrumentation and control the first section discussing temperature measurement and the second dealing with instrumentation for controlling carbonaceous atmospheres. Testing inspection and quality control are covered in sections detailing inspection and quality control, hardness testing of case-hardened parts, and methods of measuring case depth. The final chapter is an atlas of microstructures and macrostructures of case hardened parts.

  12. Case hardening of sandstone

    NASA Astrophysics Data System (ADS)

    Conca, James L.; Rossman, George R.

    1982-10-01

    The case-hardened crust developed on the Aztec Sandstone in the Valley of Fire, Nevada, has been characterized by a variety of techniques, including electron microscopy and infrared spectroscopy. The case-hardened crust consists mainly of host rock, with a fine-grained cement and wind-deposited kaolinite. The cement is usually calcite, but in some cases the hydrated calcium borate, colemanite, was found to be the case-hardening cement.

  13. Hardening of the arteries

    MedlinePLUS

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

  14. Rapid determination of immunoglobulin G concentration in cold ethanol precipitation process of raw plasma with near-infrared spectroscopy

    NASA Astrophysics Data System (ADS)

    Zhang, Hui; Liu, Aihua; Zang, Hengchang; Li, Hu; Jiang, Wei; Li, Lian; Wang, Jinfeng

    2013-12-01

    Near-infrared spectroscopy (NIRS) is known to be a powerful analytical tool in process monitoring. The feasibility of NIRS was investigated for determination of immunoglobulin G (IgG) in raw plasma cold ethanol precipitation process. Partial least squares (PLS) was used to develop regression model for 63 samples between spectra and reference data measured with a UV spectrophotometer. Three different variable selection methods, including correlation coefficient method, interval partial least squares (iPLS) and successive projection algorithm (SPA), were performed and compared with models based on all the variables. The values of Rc and root mean square error of cross validation (RMSECV) produced by the best model for the calibration set were 0.9599 and 0.6135 g/L, respectively. While for the validation set, the values of Rp and root mean square error of prediction (RMSEP) were 0.9577 and 0.4913 g/L, respectively. The results of this paper demonstrated that NIRS could be a feasible alternative approach for rapid determination of IgG in the cold ethanol precipitation process and can be used as a PAT tool in the future.

  15. Correlation between Cold- and Drought-Induced Frost Hardiness in Winter Wheat and Rye Varieties.

    PubMed

    Cloutier, Y; Siminovitch, D

    1982-01-01

    Exposure of six wheat (Triticum aestivum L.) and one rye (Secale cereale L.) cultivar to 40% relative humidity for 24 hours induced the same degree of freezing tolerance in seedling epicotyls as did cold conditioning for 4 weeks at 2 degrees C.Frost hardiness varietal relationships were the same in desiccation-stressed and cold-hardened seedlings. Drought stress could, therefore, be used as a rapid and simple method for inducing frost hardiness in seedling shoots in replacement of cold conditioning. PMID:16662170

  16. Calcium signaling mediates cold sensing in insect tissues.

    PubMed

    Teets, Nicholas M; Yi, Shu-Xia; Lee, Richard E; Denlinger, David L

    2013-05-28

    The ability to rapidly respond to changes in temperature is a critical adaptation for insects and other ectotherms living in thermally variable environments. In a process called rapid cold hardening (RCH), insects significantly enhance cold tolerance following brief (i.e., minutes to hours) exposure to nonlethal chilling. Although the ecological relevance of RCH is well-established, the underlying physiological mechanisms that trigger RCH are poorly understood. RCH can be elicited in isolated tissues ex vivo, suggesting cold-sensing and downstream hardening pathways are governed by brain-independent signaling mechanisms. We previously provided preliminary evidence that calcium is involved in RCH, and here we firmly establish that calcium signaling mediates cold sensing in insect tissues. In tracheal cells of the freeze-tolerant goldenrod gall fly, Eurosta solidaginis, chilling to 0 °C evoked a 40% increase in intracellular calcium concentration as determined by live-cell confocal imaging. Downstream of calcium entry, RCH conditions significantly increased the activity of calcium/calmodulin-dependent protein kinase II (CaMKII) while reducing phosphorylation of the inhibitory Thr306 residue. Pharmacological inhibitors of calcium entry, calmodulin activation, and CaMKII activity all prevented ex vivo RCH in midgut and salivary gland tissues, indicating that calcium signaling is required for RCH to occur. Similar results were obtained for a freeze-intolerant species, adults of the flesh fly, Sarcophaga bullata, suggesting that calcium-mediated cold sensing is a general feature of insects. Our results imply that insect tissues use calcium signaling to instantly detect decreases in temperature and trigger downstream cold-hardening mechanisms. PMID:23671084

  17. Calcium signaling mediates cold sensing in insect tissues

    PubMed Central

    Teets, Nicholas M.; Yi, Shu-Xia; Lee, Richard E.; Denlinger, David L.

    2013-01-01

    The ability to rapidly respond to changes in temperature is a critical adaptation for insects and other ectotherms living in thermally variable environments. In a process called rapid cold hardening (RCH), insects significantly enhance cold tolerance following brief (i.e., minutes to hours) exposure to nonlethal chilling. Although the ecological relevance of RCH is well-established, the underlying physiological mechanisms that trigger RCH are poorly understood. RCH can be elicited in isolated tissues ex vivo, suggesting cold-sensing and downstream hardening pathways are governed by brain-independent signaling mechanisms. We previously provided preliminary evidence that calcium is involved in RCH, and here we firmly establish that calcium signaling mediates cold sensing in insect tissues. In tracheal cells of the freeze-tolerant goldenrod gall fly, Eurosta solidaginis, chilling to 0 °C evoked a 40% increase in intracellular calcium concentration as determined by live-cell confocal imaging. Downstream of calcium entry, RCH conditions significantly increased the activity of calcium/calmodulin-dependent protein kinase II (CaMKII) while reducing phosphorylation of the inhibitory Thr306 residue. Pharmacological inhibitors of calcium entry, calmodulin activation, and CaMKII activity all prevented ex vivo RCH in midgut and salivary gland tissues, indicating that calcium signaling is required for RCH to occur. Similar results were obtained for a freeze-intolerant species, adults of the flesh fly, Sarcophaga bullata, suggesting that calcium-mediated cold sensing is a general feature of insects. Our results imply that insect tissues use calcium signaling to instantly detect decreases in temperature and trigger downstream cold-hardening mechanisms. PMID:23671084

  18. Cold nuclear matter physics at forward rapidities from d+Au collisions in PHENIX

    E-print Network

    Mickey Chiu

    2011-09-09

    We present measurements by the PHENIX experiment at RHIC of di-hadron pair production in \\dAu collisions where the particles in the pair are varied across a wide range of pseudorapidity, out to $\\eta = 3.8$. With di-hadrons, varying the $p_T$ and rapidity of the particles in the di-hadron pair allows studying any effects as a function of partonic $x$ in the nucleus. These di-hadron measurements might probe down to parton momentum fractions x $\\sim$ $10^{-3}$ in the gold nucleus, where the interesting possibility of observing gluon saturation effects at RHIC is the greatest. Our measurements show that the correlated yield of back-to-back pairs in \\dAu collisions is suppressed by up to an order of magnitude relative to \\pp collisions, and increases with greater nuclear path thickness and with a selection for lower x in the Au nucleus.

  19. Oleic acid is elevated in cell membranes during rapid cold-hardening and pupal diapause in the flesh fly, Sarcophaga crassipalpis

    Microsoft Academic Search

    M. Robert Michaud; David L. Denlinger

    2006-01-01

    The integrity of cellular membranes is critical to the survival of insects at low temperatures, thus an advantage is conferred to insects that can adjust their composition of membrane fatty acids (FAs). Such changes contribute to homeoviscous adaption, a process that allows cellular membranes to maintain a liquid-crystalline state at temperatures that are potentially low enough to cause the membrane

  20. 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

  1. Hardened solar photovoltaics

    Microsoft Academic Search

    W. P. Rahilly; J. W. Geis; L. D. Massie

    1977-01-01

    This paper reviews hardening of space photovoltaic power systems in terms of survivability to natural and artificial environments. The specific environments considered are the normal electron and proton fluxes (including proton flares) comprising the Van Allen belt; the X-ray, neutron and electromagnetic pulse environments attendant with nuclear weapon detonation and the various laser environments presently achievable. The effects of these

  2. Mark Harden's Artchive

    NSDL National Science Digital Library

    Curated by Mark Harden, the Artchive presents a useful collection of art images, text, and articles for art historians from armchair to professional levels. The Artchive itself contains some 2,300 scans of works by more than 200 artists, all accompanied by at least identifying titles, dates, artists's names, and a physical description of the original work. Harden believes that art reproductions require accompanying contextual information, and often he includes analysis and criticism by leading art historical scholars. Read Robert Hughes's short entry on the late Basquiat for a sample, or move to the Theory and Criticism section for excerpts from the canon of art history, such as E.H. Gombrich's analysis of Botticelli's Birth of Venus, or Meyer Schapiro on Cezanne. Harden employs the Web extremely effectively for presentation of art information; for example, the Schapiro Cezanne essay is divided into eight sections, each accompanied by an image of the work discussed. Other highlights of the site include Galleries, featuring changing online exhibitions; Juxtapositions, verbal/ visual commentaries on art written by Harden; and contributed reviews of commercially available art CD-ROM products.

  3. 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.

  4. Cold plasma rapid decontamination of food contact surfaces contaminated with Salmonella and Escherichia coli 0157:H7

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Cross-contamination of fresh produce from persistent pathogen reservoirs is a known risk factor in processing environments. Industry requires a waterless, zero-contact, chemical-free method for removing pathogens from food-contact surfaces. Cold plasma was tested for its ability to remove biofilms f...

  5. The response of the antennal cold receptor of Periplaneta americana to rapid temperature changes and to steady temperature

    Microsoft Academic Search

    Richard Loftus

    1968-01-01

    1.Ventrally located cold sensilla on the antennae of male adult Periplaneta americana are ring-shaped structures about 8 µ in diameter with a short hair emerging from their center (Figs. 1, 2).2.Further experiments (cf. Loftus, 1966) have substantiated the exclusion of the motion of air streams (2.5 m\\/sec) as a stimulus. The list of pure and mixed chemicals has been extended.

  6. Cold stress causes rapid but differential changes in properties of plasma membrane H(+)-ATPase of camelina and rapeseed.

    PubMed

    Kim, Hyun-Sung; Oh, Jung-Min; Luan, Sheng; Carlson, John E; Ahn, Sung-Ju

    2013-06-15

    Camelina (Camelina sativa) and rapeseed (Brassica napus) are well-established oil-seed crops with great promise also for biofuels. Both are cold-tolerant, and camelina is regarded to be especially appropriate for production on marginal lands. We examined physiological and biochemical alterations in both species during cold stress treatment for 3 days and subsequent recovery at the temperature of 25°C for 0, 0.25, 0.5, 1, 2, 6, and 24h, with particular emphasis on the post-translational regulation of the plasma membrane (PM) H(+)-ATPase (EC3.6.3.14). The activity and translation of the PM H(+)-ATPase, as well as 14-3-3 proteins, increased after 3 days of cold stress in both species but recovery under normal conditions proceeded differently. The increase in H(+)-ATPase activity was the most dramatic in camelina roots after recovery for 2h at 25°C, followed by decay to background levels within 24h. In rapeseed, the change in H(+)-ATPase activity during the recovery period was less pronounced. Furthermore, H(+)-pumping increased in both species after 15min recovery, but to twice the level in camelina roots compared to rapeseed. Protein gel blot analysis with phospho-threonine anti-bodies showed that an increase in phosphorylation levels paralleled the increase in H(+)-transport rate. Thus our results suggest that cold stress and recovery in camelina and rapeseed are associated with PM H(+)-fluxes that may be regulated by specific translational and post-translational modifications. PMID:23399403

  7. Cold-nuclear-matter effects on heavy-quark production at forward and backward rapidity in d + Au collisions at ?sNN = 200??GeV.

    PubMed

    Adare, A; Aidala, C; Ajitanand, N N; Akiba, Y; Akimoto, R; Al-Bataineh, H; Al-Ta'ani, H; Alexander, J; Andrews, K R; Angerami, A; Aoki, K; Apadula, N; Appelt, E; Aramaki, Y; Armendariz, R; Aschenauer, E C; Atomssa, E T; Averbeck, R; Awes, T C; Azmoun, B; Babintsev, V; Bai, M; Baksay, G; Baksay, L; Bannier, B; Barish, K N; Bassalleck, B; Basye, A T; Bathe, S; Baublis, V; Baumann, C; Bazilevsky, A; Belikov, S; Belmont, R; Ben-Benjamin, J; Bennett, R; Bhom, J H; Blau, D S; Bok, J S; Boyle, K; Brooks, M L; Broxmeyer, D; Buesching, H; Bumazhnov, V; Bunce, G; Butsyk, S; Campbell, S; Caringi, A; Castera, P; Chen, C-H; Chi, C Y; Chiu, M; Choi, I J; Choi, J B; Choudhury, R K; Christiansen, P; Chujo, T; Chung, P; Chvala, O; Cianciolo, V; Citron, Z; Cole, B A; Conesa Del Valle, Z; Connors, M; Csanád, M; Csörg?, T; Dahms, T; Dairaku, S; Danchev, I; Das, K; Datta, A; David, G; Dayananda, M K; Denisov, A; Deshpande, A; Desmond, E J; Dharmawardane, K V; Dietzsch, O; Dion, A; Donadelli, M; Drapier, O; Drees, A; Drees, K A; Durham, J M; Durum, A; Dutta, D; D'Orazio, L; Edwards, S; Efremenko, Y V; Ellinghaus, F; Engelmore, T; Enokizono, A; En'yo, H; Esumi, S; Fadem, B; Fields, D E; Finger, M; Finger, M; Fleuret, F; Fokin, S L; Fraenkel, Z; Frantz, J E; Franz, A; Frawley, A D; Fujiwara, K; Fukao, Y; Fusayasu, T; Gal, C; Garishvili, I; Glenn, A; Gong, H; Gong, X; Gonin, M; Goto, Y; Granier de Cassagnac, R; Grau, N; Greene, S V; Grim, G; Grosse Perdekamp, M; Gunji, T; Guo, L; Gustafsson, H-Å; Haggerty, J S; Hahn, K I; Hamagaki, H; Hamblen, J; Han, R; Hanks, J; Harper, C; Hashimoto, K; Haslum, E; Hayano, R; He, X; Heffner, M; Hemmick, T K; Hester, T; Hill, J C; Hohlmann, M; Hollis, R S; Holzmann, W; Homma, K; Hong, B; Horaguchi, T; Hori, Y; Hornback, D; Huang, S; Ichihara, T; Ichimiya, R; Iinuma, H; Ikeda, Y; Imai, K; Inaba, M; Iordanova, A; Isenhower, D; Ishihara, M; Issah, M; Ivanischev, D; Iwanaga, Y; Jacak, B V; Jia, J; Jiang, X; Jin, J; John, D; Johnson, B M; Jones, T; Joo, K S; Jouan, D; Jumper, D S; Kajihara, F; Kamin, J; Kaneti, S; Kang, B H; Kang, J H; Kang, J S; Kapustinsky, J; Karatsu, K; Kasai, M; Kawall, D; Kawashima, M; Kazantsev, A V; Kempel, T; Khanzadeev, A; Kijima, K M; Kikuchi, J; Kim, A; Kim, B I; Kim, D J; Kim, E-J; Kim, Y-J; Kim, Y K; Kinney, E; Kiss, A; Kistenev, E; Kleinjan, D; Kline, P; Kochenda, L; Komkov, B; Konno, M; Koster, J; Kotov, D; Král, A; Kravitz, A; Kunde, G J; Kurita, K; Kurosawa, M; Kwon, Y; Kyle, G S; Lacey, R; Lai, Y S; Lajoie, J G; Lebedev, A; Lee, D M; Lee, J; Lee, K B; Lee, K S; Lee, S H; Lee, S R; Leitch, M J; Leite, M A L; Li, X; Lichtenwalner, P; Liebing, P; Lim, S H; Linden Levy, L A; Liška, T; Liu, H; Liu, M X; Love, B; Lynch, D; Maguire, C F; Makdisi, Y I; Malik, M D; Manion, A; Manko, V I; Mannel, E; Mao, Y; Masui, H; Matathias, F; McCumber, M; McGaughey, P L; McGlinchey, D; McKinney, C; Means, N; Mendoza, M; Meredith, B; Miake, Y; Mibe, T; Mignerey, A C; Miki, K; Milov, A; Mitchell, J T; Miyachi, Y; Mohanty, A K; Moon, H J; Morino, Y; Morreale, A; Morrison, D P; Motschwiller, S; Moukhanova, T V; Murakami, T; Murata, J; Nagamiya, S; Nagle, J L; Naglis, M; Nagy, M I; Nakagawa, I; Nakamiya, Y; Nakamura, K R; Nakamura, T; Nakano, K; Nam, S; Newby, J; Nguyen, M; Nihashi, M; Nouicer, R; Nyanin, A S; Oakley, C; O'Brien, E; Oda, S X; Ogilvie, C A; Oka, M; Okada, K; Onuki, Y; Oskarsson, A; Ouchida, M; Ozawa, K; Pak, R; Pantuev, V; Papavassiliou, V; Park, B H; Park, I H; Park, S K; Park, W J; Pate, S F; Patel, L; Pei, H; Peng, J-C; Pereira, H; Peressounko, D Yu; Petti, R; Pinkenburg, C; Pisani, R P; Proissl, M; Purschke, M L; Qu, H; Rak, J; Ravinovich, I; Read, K F; Rembeczki, S; Reygers, K; Riabov, V; Riabov, Y; Richardson, E; Roach, D; Roche, G; Rolnick, S D; Rosati, M; Rosen, C A; Rosendahl, S S E; Ruži?ka, P; Sahlmueller, B; Saito, N; Sakaguchi, T; Sakashita, K; Samsonov, V; Sano, S; Sarsour, M; Sato, T; Savastio, M; Sawada, S; Sedgwick, K; Seele, J; Seidl, R; Seto, R; Sharma, D; Shein, I; Shibata, T-A; Shigaki, K; Shim, H H; Shimomura, M; Shoji, K; Shukla, P; Sickles, A; Silva, C L; Silvermyr, D; Silvestre, C; Sim, K S; Singh, B K; Singh, C P; Singh, V; Slune?ka, M; Sodre, T; Soltz, R A; Sondheim, W E; Sorensen, S P; Sourikova, I V; Stankus, P W; Stenlund, E; Stoll, S P; Sugitate, T; Sukhanov, A; Sun, J; Sziklai, J; Takagui, E M; Takahara, A; Taketani, A; Tanabe, R; Tanaka, Y; Taneja, S; Tanida, K; Tannenbaum, M J; Tarafdar, S; Taranenko, A; Tennant, E; Themann, H; Thomas, D; Thomas, T L; Togawa, M; Toia, A; Tomášek, L; Tomášek, M; Torii, H; Towell, R S; Tserruya, I; Tsuchimoto, Y; Utsunomiya, K; Vale, C; Valle, H; van Hecke, H W; Vazquez-Zambrano, E; Veicht, A; Velkovska, J; Vértesi, R; Virius, M; Vossen, A; Vrba, V; Vznuzdaev, E; Wang, X R; Watanabe, D; Watanabe, K; Watanabe, Y; Watanabe, Y S; Wei, F; Wei, R; Wessels, J; White, S N; Winter, D; Woody, C L; Wright, R M; Wysocki, M

    2014-06-27

    The PHENIX experiment has measured open heavy-flavor production via semileptonic decay over the transverse momentum range 1 < p(T) < 6??GeV/c at forward and backward rapidity (1.4 < |y| < 2.0) in d+Au and p + p collisions at ?sNN = 200??GeV. In central d+Au collisions, relative to the yield in p + p collisions scaled by the number of binary nucleon-nucleon collisions, a suppression is observed at forward rapidity (in the d-going direction) and an enhancement at backward rapidity (in the Au-going direction). Predictions using nuclear-modified-parton-distribution functions, even with additional nuclear-p(T) broadening, cannot simultaneously reproduce the data at both rapidity ranges, which implies that these models are incomplete and suggests the possible importance of final-state interactions in the asymmetric d + Au collision system. These results can be used to probe cold-nuclear-matter effects, which may significantly affect heavy-quark production, in addition to helping constrain the magnitude of charmonia-breakup effects in nuclear matter. PMID:25014805

  8. Cold-Nuclear-Matter Effects on Heavy-Quark Production at Forward and Backward Rapidity in d +Au Collisions at ?sNN =200 GeV

    NASA Astrophysics Data System (ADS)

    Adare, A.; Aidala, C.; Ajitanand, N. N.; Akiba, Y.; Akimoto, R.; Al-Bataineh, H.; Al-Ta'Ani, H.; Alexander, J.; Andrews, K. R.; Angerami, A.; Aoki, K.; Apadula, N.; Appelt, E.; Aramaki, Y.; Armendariz, R.; Aschenauer, E. C.; Atomssa, E. T.; Averbeck, R.; Awes, T. C.; Azmoun, B.; Babintsev, V.; Bai, M.; Baksay, G.; Baksay, L.; Bannier, B.; Barish, K. N.; Bassalleck, B.; Basye, A. T.; Bathe, S.; Baublis, V.; Baumann, C.; Bazilevsky, A.; Belikov, S.; Belmont, R.; Ben-Benjamin, J.; Bennett, R.; Bhom, J. H.; Blau, D. S.; Bok, J. S.; Boyle, K.; Brooks, M. L.; Broxmeyer, D.; Buesching, H.; Bumazhnov, V.; Bunce, G.; Butsyk, S.; Campbell, S.; Caringi, A.; Castera, P.; Chen, C.-H.; Chi, C. Y.; Chiu, M.; Choi, I. J.; Choi, J. B.; Choudhury, R. K.; Christiansen, P.; Chujo, T.; Chung, P.; Chvala, O.; Cianciolo, V.; Citron, Z.; Cole, B. A.; Conesa Del Valle, Z.; Connors, M.; Csanád, M.; Csörg?, T.; Dahms, T.; Dairaku, S.; Danchev, I.; Das, K.; Datta, A.; David, G.; Dayananda, M. K.; Denisov, A.; Deshpande, A.; Desmond, E. J.; Dharmawardane, K. V.; Dietzsch, O.; Dion, A.; Donadelli, M.; Drapier, O.; Drees, A.; Drees, K. A.; Durham, J. M.; Durum, A.; Dutta, D.; D'Orazio, L.; Edwards, S.; Efremenko, Y. V.; Ellinghaus, F.; Engelmore, T.; Enokizono, A.; En'yo, H.; Esumi, S.; Fadem, B.; Fields, D. E.; Finger, M.; Finger, M.; Fleuret, F.; Fokin, S. L.; Fraenkel, Z.; Frantz, J. E.; Franz, A.; Frawley, A. D.; Fujiwara, K.; Fukao, Y.; Fusayasu, T.; Gal, C.; Garishvili, I.; Glenn, A.; Gong, H.; Gong, X.; Gonin, M.; Goto, Y.; Granier de Cassagnac, R.; Grau, N.; Greene, S. V.; Grim, G.; Grosse Perdekamp, M.; Gunji, T.; Guo, L.; Gustafsson, H.-Å.; Haggerty, J. S.; Hahn, K. I.; Hamagaki, H.; Hamblen, J.; Han, R.; Hanks, J.; Harper, C.; Hashimoto, K.; Haslum, E.; Hayano, R.; He, X.; Heffner, M.; Hemmick, T. K.; Hester, T.; Hill, J. C.; Hohlmann, M.; Hollis, R. S.; Holzmann, W.; Homma, K.; Hong, B.; Horaguchi, T.; Hori, Y.; Hornback, D.; Huang, S.; Ichihara, T.; Ichimiya, R.; Iinuma, H.; Ikeda, Y.; Imai, K.; Inaba, M.; Iordanova, A.; Isenhower, D.; Ishihara, M.; Issah, M.; Ivanischev, D.; Iwanaga, Y.; Jacak, B. V.; Jia, J.; Jiang, X.; Jin, J.; John, D.; Johnson, B. M.; Jones, T.; Joo, K. S.; Jouan, D.; Jumper, D. S.; Kajihara, F.; Kamin, J.; Kaneti, S.; Kang, B. H.; Kang, J. H.; Kang, J. S.; Kapustinsky, J.; Karatsu, K.; Kasai, M.; Kawall, D.; Kawashima, M.; Kazantsev, A. V.; Kempel, T.; Khanzadeev, A.; Kijima, K. M.; Kikuchi, J.; Kim, A.; Kim, B. I.; Kim, D. J.; Kim, E.-J.; Kim, Y.-J.; Kim, Y. K.; Kinney, E.; Kiss, Á.; Kistenev, E.; Kleinjan, D.; Kline, P.; Kochenda, L.; Komkov, B.; Konno, M.; Koster, J.; Kotov, D.; Král, A.; Kravitz, A.; Kunde, G. J.; Kurita, K.; Kurosawa, M.; Kwon, Y.; Kyle, G. S.; Lacey, R.; Lai, Y. S.; Lajoie, J. G.; Lebedev, A.; Lee, D. M.; Lee, J.; Lee, K. B.; Lee, K. S.; Lee, S. H.; Lee, S. R.; Leitch, M. J.; Leite, M. A. L.; Li, X.; Lichtenwalner, P.; Liebing, P.; Lim, S. H.; Linden Levy, L. A.; Liška, T.; Liu, H.; Liu, M. X.; Love, B.; Lynch, D.; Maguire, C. F.; Makdisi, Y. I.; Malik, M. D.; Manion, A.; Manko, V. I.; Mannel, E.; Mao, Y.; Masui, H.; Matathias, F.; McCumber, M.; McGaughey, P. L.; McGlinchey, D.; McKinney, C.; Means, N.; Mendoza, M.; Meredith, B.; Miake, Y.; Mibe, T.; Mignerey, A. C.; Miki, K.; Milov, A.; Mitchell, J. T.; Miyachi, Y.; Mohanty, A. K.; Moon, H. J.; Morino, Y.; Morreale, A.; Morrison, D. P.; Motschwiller, S.; Moukhanova, T. V.; Murakami, T.; Murata, J.; Nagamiya, S.; Nagle, J. L.; Naglis, M.; Nagy, M. I.; Nakagawa, I.; Nakamiya, Y.; Nakamura, K. R.; Nakamura, T.; Nakano, K.; Nam, S.; Newby, J.; Nguyen, M.; Nihashi, M.; Nouicer, R.; Nyanin, A. S.; Oakley, C.; O'Brien, E.; Oda, S. X.; Ogilvie, C. A.; Oka, M.; Okada, K.; Onuki, Y.; Oskarsson, A.; Ouchida, M.; Ozawa, K.; Pak, R.; Pantuev, V.; Papavassiliou, V.; Park, B. H.; Park, I. H.; Park, S. K.; Park, W. J.; Pate, S. F.; Patel, L.; Pei, H.; Peng, J.-C.; Pereira, H.; Peressounko, D. Yu.; Petti, R.; Pinkenburg, C.; Pisani, R. P.; Proissl, M.; Purschke, M. L.; Qu, H.; Rak, J.; Ravinovich, I.; Read, K. F.; Rembeczki, S.; Reygers, K.; Riabov, V.; Riabov, Y.; Richardson, E.; Roach, D.; Roche, G.; Rolnick, S. D.; Rosati, M.; Rosen, C. A.; Rosendahl, S. S. E.; Ruži?ka, P.; Sahlmueller, B.; Saito, N.; Sakaguchi, T.; Sakashita, K.; Samsonov, V.; Sano, S.; Sarsour, M.; Sato, T.; Savastio, M.; Sawada, S.; Sedgwick, K.; Seele, J.; Seidl, R.; Seto, R.; Sharma, D.; Shein, I.; Shibata, T.-A.; Shigaki, K.; Shim, H. H.; Shimomura, M.; Shoji, K.; Shukla, P.; Sickles, A.; Silva, C. L.; Silvermyr, D.; Silvestre, C.; Sim, K. S.; Singh, B. K.; Singh, C. P.; Singh, V.; Slune?ka, M.; Sodre, T.; Soltz, R. A.; Sondheim, W. E.; Sorensen, S. P.; Sourikova, I. V.; Stankus, P. W.; Stenlund, E.; Stoll, S. P.; Sugitate, T.; Sukhanov, A.; Sun, J.; Sziklai, J.; Takagui, E. M.

    2014-06-01

    The PHENIX experiment has measured open heavy-flavor production via semileptonic decay over the transverse momentum range 1rapidity (1.4<|y|<2.0) in d +Au and p+p collisions at ?sNN =200 GeV. In central d +Au collisions, relative to the yield in p+p collisions scaled by the number of binary nucleon-nucleon collisions, a suppression is observed at forward rapidity (in the d-going direction) and an enhancement at backward rapidity (in the Au-going direction). Predictions using nuclear-modified-parton-distribution functions, even with additional nuclear-pT broadening, cannot simultaneously reproduce the data at both rapidity ranges, which implies that these models are incomplete and suggests the possible importance of final-state interactions in the asymmetric d +Au collision system. These results can be used to probe cold-nuclear-matter effects, which may significantly affect heavy-quark production, in addition to helping constrain the magnitude of charmonia-breakup effects in nuclear matter.

  9. Solute Enhanced Strain Hardening of Aluminum Alloys to Achieve Improved Combinations of Strength and Toughness

    NASA Astrophysics Data System (ADS)

    Hovanec, Christopher James

    2011-12-01

    The feasibility of achieving improved combinations of strength and toughness in aluminum alloy 2524 through solute enhanced strain hardening (SESH) has been explored in this study and shown to be viable. The effectiveness of SESH is directly dependent on the strain hardening rate (SHR) of the material being processed. Aluminum alloy 2524 naturally ages to the T4-temper after solution heat treating and quenching. The SHR of strain free and post cold rolled material as a function of natural aging time has been measured by means of simple compression. It has been determined that the SHR of AA2524 is more effective with solute in solution rather than clustered into GP zones. It has also been shown that the typical rapid formation of GP zones at room temperature (natural aging) is inhibited by moderate cold rolling strains (?CR ? 0.2) through dislocation aided vacancy annihilation. The practical limitations of quenching rate have been determined using hardness and eddy current electrical conductivity measurements. It has been shown that too slow of a quench rate results in solute being lost to both the formation of GP zones and embrittling precipitates during the quench, while too rapid of a quench rate results in mid-plane cracking of the work piece during the SESH processing. The mid-plane cracking was overcome by using an uphill quenching procedure to relieve residual stresses within the work piece. Aluminum alloy 2524 strengthened through SESH to a yield strength 11% greater than that in the T6-Temper exhibits: equivalent toughness, 5% greater UTS, 1% greater elongation, 7% greater R.A., and absorbs 15% more energy during tensile testing. At yield strengths comparable to published data for 2x24 alloys, the SESH 2524 exhibited up to a 60% increase in fracture toughness. The fractured surfaces of the SESH material exhibited transgranular dimpled rupture as opposed to the grain boundary ductile fracture (GBPF) observed in the artificially aged material.

  10. Induction Hardening vs Conventional Hardening of a Heat Treatable Steel

    NASA Astrophysics Data System (ADS)

    Sackl, Stephanie; Leitner, Harald; Zuber, Michael; Clemens, Helmut; Primig, Sophie

    2014-11-01

    This study focuses on the comparison of mechanical and microstructural properties of induction and conventionally heat-treated steels in the as-quenched state. The investigated steel is a heat treatable 42CrMo4 steel. In order to characterize the mechanical properties, tensile tests and Vickers hardness tests are performed. The yield strength and hardness of the induction hardened condition turn out to be slightly lower compared to the conventionally hardened one. Light optical and scanning electron microscopy show no differences in the martensitic structure of the induction and conventionally hardened condition. However, electron back scatter diffraction investigations reveal a smaller block size within the conventionally hardened specimen. Carbon mappings by electron probe micro analysis show a homogenous carbon concentration in the conventionally hardened and a non-uniform distribution in the induction-hardened case. The segregation of the carbon exhibits line-type features in the induction hardened condition, lowering the total amount of carbon in the matrix. Therefore, the carbon content in the matrix of the conventionally hardened condition is slightly higher, which causes a smaller block size. The smaller block size is believed to be the reason for the higher hardness and yield strength.

  11. Deformation mechanisms of metals hardened by a dispersed, incoherent, second phase

    Microsoft Academic Search

    P. Guyot; E. Ruedl

    1967-01-01

    Hardening of fcc metals by incoherent particles is analysed. The presence of the particles indirectly determines the rapid multiplication of dislocations in the matrix. The hardening is related to the dense tangles so formed. Recovery of these tangles occurs by cross-slip, climb, and probably by some other complex, thermally activated mechanisms.

  12. Effect of shot peening on the microstructure of laser hardened 17-4PH

    NASA Astrophysics Data System (ADS)

    Wang, Zhou; Jiang, Chuanhai; Gan, Xiaoyan; Chen, Yanhua

    2010-12-01

    In order to investigate the influence of shot peening on microstructure of laser hardened steel and clarify how much influence of initial microstructure induced by laser hardening treatment on final microstructure of laser hardened steel after shot peening treatment, measurements of retained austenite, measurements of microhardness and microstructural analysis were carried out on three typical areas including laser hardened area, transitional area and matrix area of laser hardened 17-4PH steel. The results showed that shot peening was an efficient cold working method to eliminate the retained austenite on the surface of laser hardened samples. The surface hardness increased dramatically when shot peening treatments were carried out. The analyses of microstructure of laser hardened 17-4PH after shot peening treatment were carried out in matrix area and laser hardened area via Voigt method. With the increasing peening intensity, the influence depth of shot peening on hardness and microstructure increased but the surface hardness and microstructure did not change when certain peening intensity was reached. Influence depth of shot peening on hardness was larger than influence depth of shot peening on microstructure due to the kinetic energy loss along the depth during shot peening treatment. From the microstructural result, it can be shown that the shot peening treatment can influence the domain size and microstrain of treated samples but laser hardening treatment can only influence the microstrain of treated samples.

  13. 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).

  14. Evaluation of mini-VIDAS rapid test for detection of Listeria monocytogenes from production lines of fresh to cold-smoked fish.

    PubMed

    Vaz-Velho, M; Duarte, G; Gibbs, P

    2000-04-01

    This study was conducted to evaluate the efficacy of the mini-VIDAS Listeria monocytogenes (LMO) system (BioMérieux Vitek, Inc., Missouri, USA) for detection of L. monocytogenes in environmental and fish samples from three Portuguese cold-smoking plants and from their fresh fish suppliers. Mini-VIDAS-LMO is a fully automated system that uses fluorescent ELFA (Enzyme Linked Fluorescent Assay) technology for detection of Listeria monocytogenes antigens in food. It can be a rapid screening method alternative to time consuming classical isolation and identification. Two hundred and ninety five samples were tested in mini-VIDAS-LMO and in parallel by the ISO 11290-1 traditional protocol. The mini-VIDAS-LMO detected 8 of the 11 confirmed positive samples and presented 11 false positive results. The specificity of the mini-VIDAS-LMO found in this experiment was 0.96 and the sensitivity 0.73. PMID:10699670

  15. Combined transcriptomic and metabolomic approach uncovers molecular mechanisms of cold tolerance in a temperate flesh fly.

    PubMed

    Teets, Nicholas M; Peyton, Justin T; Ragland, Gregory J; Colinet, Herve; Renault, David; Hahn, Daniel A; Denlinger, David L

    2012-08-01

    The ability to respond rapidly to changes in temperature is critical for insects and other ectotherms living in variable environments. In a physiological process termed rapid cold-hardening (RCH), exposure to nonlethal low temperature allows many insects to significantly increase their cold tolerance in a matter of minutes to hours. Additionally, there are rapid changes in gene expression and cell physiology during recovery from cold injury, and we hypothesize that RCH may modulate some of these processes during recovery. In this study, we used a combination of transcriptomics and metabolomics to examine the molecular mechanisms of RCH and cold shock recovery in the flesh fly, Sarcophaga bullata. Surprisingly, out of ?15,000 expressed sequence tags (ESTs) measured, no transcripts were upregulated during RCH, and likewise RCH had a minimal effect on the transcript signature during recovery from cold shock. However, during recovery from cold shock, we observed differential expression of ?1,400 ESTs, including a number of heat shock proteins, cytoskeletal components, and genes from several cell signaling pathways. In the metabolome, RCH had a slight yet significant effect on several metabolic pathways, while cold shock resulted in dramatic increases in gluconeogenesis, amino acid synthesis, and cryoprotective polyol synthesis. Several biochemical pathways showed congruence at both the transcript and metabolite levels, indicating that coordinated changes in gene expression and metabolism contribute to recovery from cold shock. Thus, while RCH had very minor effects on gene expression, recovery from cold shock elicits sweeping changes in gene expression and metabolism along numerous cell signaling and biochemical pathways. PMID:22735925

  16. Phase Stability of Al-5Fe-V-Si Coatings Produced by Cold Gas Dynamic Spray Process Using Rapidly Solidified Feedstock Materials

    NASA Astrophysics Data System (ADS)

    Bérubé, G.; Yandouzi, M.; Zúñiga, A.; Ajdelsztajn, L.; Villafuerte, J.; Jodoin, B.

    2012-03-01

    In this study, aluminum alloy Al-5Fe-V-Si (in wt.%) feedstock powder, produced by rapid solidification (RS) using the gas atomization process, was selected to produce high-temperature resistant Al-alloy coatings using the cold gas dynamic spraying process (CGDS). The alloy composition was chosen for its mechanical properties at elevated temperature for potential applications in internal-combustion (IC) engines. The CGDS spray process was selected due to its relatively low operating temperature, thus preventing significant heating of the particles during spraying and as such allowing the original phases of the feedstock powder to be preserved within the coatings. The microstructure and phases stability was investigated by means of Scanning Electron Microscopy, transmission electron microscopy, X-ray diffraction and differential scanning calorimetery techniques. The coatings mechanical properties were evaluated through bond strength and microhardness testing. The study revealed the conservation of the complex microstructure of the rapid solidified powder during the spray process. Four distinct microstructures were observed as well as two different phases, namely a Al13(Fe,V)3Si silicide phase and a metastable (Al,Si) x (Fe,V) Micro-quasicrystalline Icosahedral (MI) phase. Aging of the coating samples was performed and confirmed that the phase transformation of the metastable phases and coarsening of the nanosized precipitates will occurs at around 400 °C. The metastable MI phase was determined to be thermally stable up to 390 °C, after which a phase transformation to silicide starts to occur.

  17. Single event upset hardening techniques

    SciTech Connect

    Weaver, H.T.; Corbett, W.T.

    1990-01-01

    Integrated circuit logic states are maintained by virtue of specific transistor combinations being either on'' (conducting) or off'' (nonconducting). High energy ion strikes on the microcircuit generate photocurrents whose primary detrimental effect is to make off'' transistors appear on,'' confusing the logic state and leading to single event upset (SEU). Protection against these soft errors is accomplished using either technology or circuit techniques, actions that generally impact yield and performance relative to unhardened circuits. We describe, and using circuit simulations analyze, a technique for hardening latches which requires combinations of technology and circuit modifications, but which provides SEU immunity without loss of speed. Specifically, a single logic state is hardened against SEU using technology methods and the information concerning valid states is then used to simplify hardened circuit design. The technique emphasizes some basic hardening concepts, ideas for which will be reviewed. 3 refs., 2 figs.

  18. How Cold Is Cold?

    NSDL National Science Digital Library

    Richard Konicek-Moran

    2008-04-01

    Heat and cold are often difficult concepts for children to understand. First, our everyday sloppy language gives them a predisposition to such common misconceptions as cold being a substance that moves from place to place. Our colloquial language often re

  19. Methods for Designing Concurrently Strengthened Severely Deformed Age-Hardenable Aluminum Alloys by Ultrafine-Grained and Precipitation Hardenings

    NASA Astrophysics Data System (ADS)

    Hirosawa, Shoichi; Hamaoka, Takumi; Horita, Zenji; Lee, Seungwon; Matsuda, Kenji; Terada, Daisuke

    2013-08-01

    The age-hardenings behavior and precipitate microstructures with high dislocation density and/or ultrafine grains have been studied for 6022Al-Mg-Si and 2091Al-Li-Cu alloys. The high-pressure torsion (HPT) specimen of the former alloy exhibited either suppressed age hardenings or even age softening, unlike in the cases of the undeformed and cold-rolled specimens, at room temperature (RT) to 443 K (170 °C). On the other hand, the HPT specimen of the latter alloy successfully increased the hardness up to >HV290 at 373 K (100 °C), suggesting that concurrent strengthening by ultrafine-grained and precipitation hardenings can be activated if both alloy system and aging temperature are optimally selected. The corresponding transmission electron microscopy (TEM) microstructures attributed such a high level of hardness to the transgranular precipitation of the nanometer-scale particles within ultrafine grains. From the results of in situ small-angle X-ray scattering (SAXS) measurements, methods to maximize the effect of the combined processing of severe plastic deformation (SPD) and the age-hardenings technique are proposed based on the underlying phase transformation mechanisms.

  20. 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.

  1. Rapid stalk elongation in tulip ( Tulipa gesneriana L. cv. Apeldoorn) and the combined action of cold-induced invertase and the water-channel protein ?TIP

    Microsoft Academic Search

    Peter A. Balk; A. Douwe de Boer

    1999-01-01

    .   Many bulbous plants need a low-temperature treatment for flowering. Cold, for example, affects the elongation of the stalk,\\u000a thereby influencing the quality of the cut flower. How the elongation of the stalk is promoted by cold and which physiological\\u000a and biochemical mechanisms are involved have remained obscure. As invertase has been shown to be involved in the cold-induced\\u000a elongation

  2. 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…

  3. Hardening of Texas Instruments' VC33 DSP

    Microsoft Academic Search

    Robert Fuller; Wesley Morris; David Gifford; Rex Lowther; Jon Gwin; James Salzman; D. Alexander; K. Hunt

    2010-01-01

    A hardened version of Texas Instruments'' VC33 Digital Signal Processor was created without any mask changes. The commercial mask set was processed using Silicon Space Technology''s HardSIL™ process variant to produce the hardened version. Radiation testing of the resulting hardened circuit demonstrated significant improvement in performance.

  4. High strength fasteners cold forged out of work hardening steel

    Microsoft Academic Search

    David C Goss

    2000-01-01

    When designing fasteners, engineers should choose materials and processes that provide the strength required for the application. And if the materials can be turned into a fastener using less manufacturing steps than traditional processes, then a company making these fasteners can save time and money. For instance, high strength bolts and screws are typically produced from annealed wire. The wire

  5. Cold tolerance of first-instar nymphs of the Australian plague locust, Chortoicetes terminifera.

    PubMed

    Woodman, James D

    2010-04-01

    The cold tolerance of first-instar nymphs of the Australian plague locust, Chortoicetes terminifera, was examined using measures of total body water content, supercooling point and mortality for a range of sub-zero temperature exposure regimes. The supercooling points for starved and fed nymphs were -13.1+/-0.9 and -12.6+/-1.6 degrees C, and freezing caused complete mortality. Above these temperatures, nymphs were cold tolerant to different degrees based on whether they were starved or given access to food and water for 24h prior to exposure. The rate of cooling also had a significant effect on mortality. Very rapid cooling to -7 degrees C caused 84 and 87% mortality for starved and fed nymphs respectively, but this significantly decreased for starved nymphs if temperature declined by more ecologically realistic rates of 0.5 and 0.1 degrees C min(-1). These results are indicative of a rapid cold hardening response and are discussed in terms of the likely effects of cold nights and frost on first-instar nymphal survival in the field. PMID:19932699

  6. Rapid responses to high temperature and desiccation but not to low temperature in the freeze tolerant sub-Antarctic caterpillar Pringleophaga marioni (Lepidoptera, Tineidae).

    PubMed

    Sinclair, Brent J; Chown, Steven L

    2003-01-01

    A broad definition of rapid cold hardening (RCH) is that it is the process whereby insects increase their survival of a sub-zero temperature after a brief (h) pre-exposure to a less severe low temperature. The effects of various pre-treatments on survival of two h at -7.9 degrees C were investigated in the freeze tolerant sub-Antarctic caterpillar Pringleophaga marioni (Lepidoptera: Tineidae), the first time RCH has been investigated in a freeze tolerant arthropod. All caterpillars froze when exposed to -7.9 degrees C, and none of the low temperature pre-treatments (-5, 0, 5 and 15 degrees C, as well as -5 degrees C and 0 degrees C with a delay before freezing) nor slow cooling (0.1 degrees C/min) elicited any improvement in survival of -7.9 degrees C as compared to controls. However, high temperature treatments (25, 30 and 35 degrees C), desiccation and acclimation for 5 days at 0 degrees C did result in significant increases in survival of the test temperature, possibly as a result of heat shock protein production. Haemolymph osmolality was elevated only by the 35 degrees C pre-treatment. It is suggested that the unpredictable environment of Marion Island means that P. marioni must always be physiologically prepared to survive cold snaps, and that this year-round cold hardiness therefore supersedes a rapid cold hardening response. PMID:12770015

  7. Rapid Low Temperature-Induced Stomatal Closure Occurs in Cold-Tolerant Commelina communis Leaves But Not in Cold-Sensitive Tobacco Leaves, via a Mechanism That Involves Apoplastic Calcium But Not Abscisic Acid1

    PubMed Central

    Wilkinson, Sally; Clephan, Alison Lee; Davies, William John

    2001-01-01

    Commelina communis stomata closed within 1 h of transferring intact plants from 27°C to 7°C, whereas tobacco (Nicotiana rustica) stomata did not until the leaves wilted. Abscisic acid (ABA) did not mediate cold-induced C. communis stomatal closure: At low temperatures, bulk leaf ABA did not increase; ABA did not preferentially accumulate in the epidermis; its flux into detached leaves was lower; its release from isolated epidermis was not greater; and stomata in epidermal strips were less sensitive to exogenous ABA. Stomata of both species in epidermal strips on large volumes of cold KCl failed to close unless calcium was supplied. Therefore, the following cannot be triggers for cold-induced stomatal closure in C. communis: direct effects of temperature on guard or epidermal cells, long-distance signals, and effects of temperature on photosynthesis. Low temperature increased stomatal sensitivity to external CaCl2 by 50% in C. communis but only by 20% in tobacco. C. communis stomata were 300- to 1,000-fold more sensitive to calcium at low temperature than tobacco stomata, but tobacco epidermis only released 13.6-fold more calcium into bathing solutions than C. communis. Stomata in C. communis epidermis incubated on ever-decreasing volumes of cold calcium-free KCl closed on the lowest volume (0.2 cm3) because the epidermal apoplast contained enough calcium to mediate closure if this was not over diluted. We propose that the basis of cold-induced stomatal closure exhibited by intact C. communis leaves is increased apoplastic calcium uptake by guard cells. Such responses do not occur in chill-sensitive tobacco leaves. PMID:11500555

  8. Work Hardening and Annealing of Copper

    NSDL National Science Digital Library

    Stoebe, Thomas G.

    This activity will demonstrate the process of work hardening and annealing of a copper. Students will get the opportunity to see the hardening of metal by deformation, experience the process of work hardening, explain the effects of work hardening in metals and experience property changes affected by annealing. This activity would be appropriate for grades 4 through high school and college level, with each age group gaining different educational benefits. Around 60 minutes is required for the demonstration. Student, instructor and course evaluation questions are included. This document will serve as a framework for instructors and may be downloaded in PDF format.

  9. Components of the hardening flavor present in hardened linseed oil and soybean oil

    Microsoft Academic Search

    J. G. Keppler; J. A. Schols; W. H. Feenstra; P. W. Meijboom

    1965-01-01

    The characteristic hardening flavor which develops in hardened linseed and soybean oils during storage has been coned from\\u000a hardened linseed oil by stripping with nitrogen. After separating the volatile substances by adsorption chromatography on\\u000a silica, the fraction containing the hardening flavor has been converted into 2,4-dinitrophenylhydrazones (DNPHs) and separated\\u000a by means of partition chromatography. On regeneration of the fractions of

  10. Can winter-active bumblebees survive the cold? Assessing the cold tolerance of Bombus terrestris audax and the effects of pollen feeding.

    PubMed

    Owen, Emily L; Bale, Jeffrey S; Hayward, Scott A L

    2013-01-01

    There is now considerable evidence that climate change is disrupting the phenology of key pollinator species. The recently reported UK winter activity of the bumblebee Bombus terrestris brings a novel set of thermal challenges to bumblebee workers that would typically only be exposed to summer conditions. Here we assess the ability of workers to survive acute and chronic cold stress (via lower lethal temperatures and lower lethal times at 0°C), the capacity for rapid cold hardening (RCH) and the influence of diet (pollen versus nectar consumption) on supercooling points (SCP). Comparisons are made with chronic cold stress indices and SCPs in queen bumblebees. Results showed worker bees were able to survive acute temperatures likely to be experienced in a mild winter, with queens significantly more tolerant to chronic cold temperature stress. The first evidence of RCH in any Hymenoptera is shown. In addition, dietary manipulation indicated the consumption of pollen significantly increased SCP temperature. These results are discussed in the light of winter active bumblebees and climate change. PMID:24224036

  11. Can Winter-Active Bumblebees Survive the Cold? Assessing the Cold Tolerance of Bombus terrestris audax and the Effects of Pollen Feeding

    PubMed Central

    Owen, Emily L.; Bale, Jeffrey S.; Hayward, Scott A. L.

    2013-01-01

    There is now considerable evidence that climate change is disrupting the phenology of key pollinator species. The recently reported UK winter activity of the bumblebee Bombus terrestris brings a novel set of thermal challenges to bumblebee workers that would typically only be exposed to summer conditions. Here we assess the ability of workers to survive acute and chronic cold stress (via lower lethal temperatures and lower lethal times at 0°C), the capacity for rapid cold hardening (RCH) and the influence of diet (pollen versus nectar consumption) on supercooling points (SCP). Comparisons are made with chronic cold stress indices and SCPs in queen bumblebees. Results showed worker bees were able to survive acute temperatures likely to be experienced in a mild winter, with queens significantly more tolerant to chronic cold temperature stress. The first evidence of RCH in any Hymenoptera is shown. In addition, dietary manipulation indicated the consumption of pollen significantly increased SCP temperature. These results are discussed in the light of winter active bumblebees and climate change. PMID:24224036

  12. COSMIC-RAY HELIUM HARDENING

    SciTech Connect

    Ohira, Yutaka; Ioka, Kunihito, E-mail: ohira@post.kek.jp [Theory Center, Institute of Particle and Nuclear Studies, KEK (High Energy Accelerator Research Organization), 1-1 Oho, Tsukuba 305-0801 (Japan)

    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.

  13. Challenges in hardening technologies using shallow-trench isolation

    Microsoft Academic Search

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

    1998-01-01

    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.

  14. Cyclic hardening mechanisms in NIMONIC 80A

    Microsoft Academic Search

    B. A. Lerch; V. Gerold

    1987-01-01

    A nickel base superalloy was fatigued under constant plastic strain range (??p) control. The hardening response was investigated as a function of ??p and particle size of the ? ? phase. Hardening was found to be a function of the slip band spacing,i. Numerous measurements ofi and other statistical data on the slip band structures were obtained. Interactions between intersecting

  15. 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.

  16. 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.

  17. A novel plant defensin-like gene of winter wheat is specifically induced during cold acclimation.

    PubMed

    Koike, Michiya; Okamoto, Takashi; Tsuda, Sakae; Imai, Ryozo

    2002-10-18

    A novel cDNA clone, Tad1, was isolated from crown tissue of winter wheat after differential screening of cold acclimation-induced genes. The Tad1 cDNA encoded a 23kDa polypeptide with a potential N-terminal signal sequence. The putative mature sequence showed striking similarity to plant defensins or gamma-thionins, representing low molecular size antipathogenic polypeptides. High levels of Tad1 mRNA accumulation occurred within one day of cold acclimation in crown tissue and the level was maintained throughout 14 days of cold acclimation. Similar rapid induction was observed in young seedlings treated with low temperature but not with exogenous abscisic acid. In contrast to defensins from other plant species, neither salicylic acid nor methyl jasmonate induced expression of Tad1. The recombinant mature form of TAD1 polypeptide inhibited the growth of the phytopathogenic bacteria, Pseudomonas cichorii; however, no antifreeze activity was detected. Collectively, these data suggested that Tad1 is induced in cold-acclimated winter wheat independent of major defense signaling(s) and is involved in low temperature-induced resistance to pathogens during winter hardening. PMID:12379218

  18. STABILIZATION AND PROCESSING CONCEPT FOR THE PRODUCTION OF ULC STEEL SHEET WITH BAKE HARDENABILITY

    Microsoft Academic Search

    Lydia Storojeva; Christine Escher; Rolf Bode; Klaus Hulka

    Ultra low carbon steels with under- to over-stoichiometric atomic ratios of Ti\\/N and Nb\\/C were industrially produced as hot and cold rolled sheet. Continuous annealing cycles were simulated, using parameters typical for industrial processing routes. Microstructure, solute carbon content, mechanical properties, as well as bake hardening and aging behaviour were studied. It turned out that the best property combination with

  19. Laser Surface Hardening of Groove Edges

    NASA Astrophysics Data System (ADS)

    Hussain, A.; Hamdani, A. H.; Akhter, R.; Aslam, M.

    2013-06-01

    Surface hardening of groove-edges made of 3Cr13 Stainless Steel has been carried out using 500 W CO2 laser with a rectangular beam of 2.5×3 mm2. The processing speed was varied from 150-500 mm/min. It was seen that the hardened depth increases with increase in laser interaction time. A maximum hardened depth of around 1mm was achieved. The microhardness of the transformed zone was 2.5 times the hardness of base metal. The XRD's and microstructural analysis were also reported.

  20. Cyclic hardening mechanisms in NIMONIC 80A

    NASA Astrophysics Data System (ADS)

    Lerch, B. A.; Gerold, V.

    1987-12-01

    A nickel base superalloy was fatigued under constant plastic strain range (??p) control. The hardening response was investigated as a function of ??p and particle size of the ? ' phase. Hardening was found to be a function of the slip band spacing, i. Numerous measurements of i 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.

  1. 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.

  2. Plastic hardening in cubic semiconductors by nanoscratching

    NASA Astrophysics Data System (ADS)

    Caldas, P. G.; Prioli, R.; Almeida, C. M.; Huang, J. Y.; Ponce, F. A.

    2011-01-01

    The effect of scratch proximity on the resistance to plastic deformation in InP (100) crystals under low normal loads has been studied using atomic force microscopy (AFM) and transmission electron microscopy. Plastic flow has been observed for scratches performed with an atomic force microscope along ?110? and ?100? crystallographic directions. Plastic hardening has been determined from AFM measurements of the scratch depth and width, as a function of the distance between parallel scratches. For relatively low loads, hardening is found to be independent of the crystallographic direction of the scratch. Significant hardening takes place for scratch separations of less than ˜80 nm. Analysis of the microstructure indicates that hardening occurs due to the interaction of dislocations generated at adjacent scratches and acting on different slip planes.

  3. Laser Applications in Metal Surface Hardening 

    E-print Network

    Eckersley, J. S.

    1982-01-01

    The acceptance of C02 lasers in industry to provide surface hardening is an established fact. Applications number in the hundreds in such diverse fields as automotive, office machines, air compressors, jet engines, military, paper converting...

  4. Cold-nuclear-matter effects on heavy-quark production at forward and backward rapidity in d+Au collisions at sqrt(s_NN)=200 GeV

    E-print Network

    A. Adare; C. Aidala; N. N. Ajitanand; Y. Akiba; R. Akimoto; H. Al-Bataineh; H. Al-Ta'ani; J. Alexander; K. R. Andrews; A. Angerami; K. Aoki; N. Apadula; E. Appelt; Y. Aramaki; R. Armendariz; E. C. Aschenauer; E. T. Atomssa; R. Averbeck; T. C. Awes; B. Azmoun; V. Babintsev; M. Bai; G. Baksay; L. Baksay; B. Bannier; K. N. Barish; B. Bassalleck; A. T. Basye; S. Bathe; V. Baublis; C. Baumann; A. Bazilevsky; S. Belikov; R. Belmont; J. Ben-Benjamin; R. Bennett; J. H. Bhom; D. S. Blau; J. S. Bok; K. Boyle; M. L. Brooks; D. Broxmeyer; H. Buesching; V. Bumazhnov; G. Bunce; S. Butsyk; S. Campbell; A. Caringi; P. Castera; C. -H. Chen; C. Y. Chi; M. Chiu; I. J. Choi; J. B. Choi; R. K. Choudhury; P. Christiansen; T. Chujo; P. Chung; O. Chvala; V. Cianciolo; Z. Citron; B. A. Cole; Z. Conesa del Valle; M. Connors; M. Csanád; T. Csörg?; T. Dahms; S. Dairaku; I. Danchev; K. Das; A. Datta; G. David; M. K. Dayananda; A. Denisov; A. Deshpande; E. J. Desmond; K. V. Dharmawardane; O. Dietzsch; A. Dion; M. Donadelli; O. Drapier; A. Drees; K. A. Drees; J. M. Durham; A. Durum; D. Dutta; L. D'Orazio; S. Edwards; Y. V. Efremenko; F. Ellinghaus; T. Engelmore; A. Enokizono; H. En'yo; S. Esumi; B. Fadem; D. E. Fields; M. Finger; M. Finger; \\, Jr.; F. Fleuret; S. L. Fokin; Z. Fraenkel; J. E. Frantz; A. Franz; A. D. Frawley; K. Fujiwara; Y. Fukao; T. Fusayasu; C. Gal; I. Garishvili; A. Glenn; H. Gong; X. Gong; M. Gonin; Y. Goto; R. Granier de Cassagnac; N. Grau; S. V. Greene; G. Grim; M. Grosse Perdekamp; T. Gunji; L. Guo; H. -Å. Gustafsson; J. S. Haggerty; K. I. Hahn; H. Hamagaki; J. Hamblen; R. Han; J. Hanks; C. Harper; K. Hashimoto; E. Haslum; R. Hayano; X. He; M. Heffner; T. K. Hemmick; T. Hester; J. C. Hill; M. Hohlmann; R. S. Hollis; W. Holzmann; K. Homma; B. Hong; T. Horaguchi; Y. Hori; D. Hornback; S. Huang; T. Ichihara; R. Ichimiya; H. Iinuma; Y. Ikeda; K. Imai; M. Inaba; A. Iordanova; D. Isenhower; M. Ishihara; M. Issah; D. Ivanischev; Y. Iwanaga; B. V. Jacak; J. Jia; X. Jiang; J. Jin; D. John; B. M. Johnson; T. Jones; K. S. Joo; D. Jouan; D. S. Jumper; F. Kajihara; J. Kamin; S. Kaneti; B. H. Kang; J. H. Kang; J. S. Kang; J. Kapustinsky; K. Karatsu; M. Kasai; D. Kawall; M. Kawashima; A. V. Kazantsev; T. Kempel; A. Khanzadeev; K. M. Kijima; J. Kikuchi; A. Kim; B. I. Kim; D. J. Kim; E. -J. Kim; Y. -J. Kim; Y. K. Kim; E. Kinney; Á. Kiss; E. Kistenev; D. Kleinjan; P. Kline; L. Kochenda; B. Komkov; M. Konno; J. Koster; D. Kotov; A. Král; A. Kravitz; G. J. Kunde; K. Kurita; M. Kurosawa; Y. Kwon; G. S. Kyle; R. Lacey; Y. S. Lai; J. G. Lajoie; A. Lebedev; D. M. Lee; J. Lee; K. B. Lee; K. S. Lee; S. H. Lee; S. R. Lee; M. J. Leitch; M. A. L. Leite; X. Li; P. Lichtenwalner; P. Liebing; S. H. Lim; L. A. Linden Levy; T. Liška; H. Liu; M. X. Liu; B. Love; D. Lynch; C. F. Maguire; Y. I. Makdisi; M. D. Malik; A. Manion; V. I. Manko; E. Mannel; Y. Mao; H. Masui; F. Matathias; M. McCumber; P. L. McGaughey; D. McGlinchey; C. McKinney; N. Means; M. Mendoza; B. Meredith; Y. Miake; T. Mibe; A. C. Mignerey; K. Miki; A. Milov; J. T. Mitchell; Y. Miyachi; A. K. Mohanty; H. J. Moon; Y. Morino; A. Morreale; D. P. Morrison; S. Motschwiller; T. V. Moukhanova; T. Murakami; J. Murata; S. Nagamiya; J. L. Nagle; M. Naglis; M. I. Nagy; I. Nakagawa; Y. Nakamiya; K. R. Nakamura; T. Nakamura; K. Nakano; S. Nam; J. Newby; M. Nguyen; M. Nihashi; R. Nouicer; A. S. Nyanin; C. Oakley; E. O'Brien; S. X. Oda; C. A. Ogilvie; M. Oka; K. Okada; Y. Onuki; A. Oskarsson; M. Ouchida; K. Ozawa; R. Pak; V. Pantuev; V. Papavassiliou; B. H. Park; I. H. Park; S. K. Park; W. J. Park; S. F. Pate; L. Patel; H. Pei; J. -C. Peng; H. Pereira; D. Yu. Peressounko; R. Petti; C. Pinkenburg; R. P. Pisani; M. Proissl; M. L. Purschke; H. Qu; J. Rak; I. Ravinovich; K. F. Read; S. Rembeczki; K. Reygers; V. Riabov; Y. Riabov; E. Richardson; D. Roach; G. Roche; S. D. Rolnick; M. Rosati; C. A. Rosen; S. S. E. Rosendahl; P. Ruži?ka; B. Sahlmueller; N. Saito; T. Sakaguchi; K. Sakashita; V. Samsonov; S. Sano; M. Sarsour; T. Sato; M. Savastio; S. Sawada; K. Sedgwick; J. Seele; R. Seidl; R. Seto; D. Sharma; I. Shein; T. -A. Shibata; K. Shigaki; H. H. Shim; M. Shimomura; K. Shoji; P. Shukla; A. Sickles; C. L. Silva; D. Silvermyr; C. Silvestre; K. S. Sim; B. K. Singh; C. P. Singh; V. Singh; M. Slune?ka; T. Sodre; R. A. Soltz; W. E. Sondheim; S. P. Sorensen; I. V. Sourikova; P. W. Stankus; E. Stenlund; S. P. Stoll; T. Sugitate; A. Sukhanov; J. Sun; J. Sziklai; E. M. Takagui; A. Takahara; A. Taketani; R. Tanabe; Y. Tanaka; S. Taneja; K. Tanida; M. J. Tannenbaum; S. Tarafdar; A. Taranenko; E. Tennant; H. Themann; D. Thomas; T. L. Thomas; M. Togawa; A. Toia; L. Tomášek; M. Tomášek; H. Torii; R. S. Towell; I. Tserruya; Y. Tsuchimoto; K. Utsunomiya; C. Vale; H. Valle; H. W. van Hecke; E. Vazquez-Zambrano; A. Veicht; J. Velkovska; R. Vértesi; M. Virius; A. Vossen; V. Vrba; E. Vznuzdaev

    2013-10-03

    The PHENIX experiment has measured open heavy-flavor production via semileptonic decay muons over the transverse momentum range 1 < pT < 6 GeV/c at forward and backward rapidity (1.4 < |y| < 2.0) in d+Au and p+p collisions at ?sNN = 200 GeV. In central d+Au collisions an enhancement (suppression) of heavy-flavor muon production is observed at backward (forward) rapidity relative to the yield in p+p collisions scaled by the number of binary collisions. Modification of the gluon density distribution in the Au nucleus contributes in terms of anti-shadowing enhancement and shadowing suppression; however, the enhancement seen at backward rapidity exceeds expectations from this effect alone. These results, implying an important role for additional cold nuclear matter effects, serves as a key baseline for heavy-quark measurements in A+A collisions and in constraining the magnitude of charmonia breakup effects at the Relativistic Heavy Ion Collider and the Large Hadron Collider.

  5. Work hardening behavior in aluminum alloy 2090

    SciTech Connect

    Tseng, C. [Lawrence Berkeley Lab., CA (United States)]|[California Univ., Berkeley, CA (United States). Dept. of Materials Science and Mineral Engineering

    1993-12-01

    An investigation into the work hardening behavior of an aluminum alloy 2090-T81 Al-3.05Cu-2.16Li-0.12Zr at various test temperatures, heat treatment conditions and microstructures was conducted. One microstructure consisted of unrecrystallized, highly textured grains, and the other microstructure was composed of recrystallized grains. Microstructural effects on work hardening were divided into two levels of contribution: the grain structure level, which consisted of the grain size and shape, subgrains and texture, and the microconsistent level, which included the precipitates and solutes. Two heat treatments were studied: the as-received, peak-aged condition, and the solution heat treated condition where the as-received plate was resolutionized. Observations of the deformed surface of both as-received grain structures at various prestrains indicated that there was no correlation between an increase in slip homogeneity and an increase in work hardening. The increase in out-of-plane grain rotation at lower temperatures was not primarily responsible for the increase in work hardening. In addition, the fully plastic deformation microstructure for the unrecrystallized microstructure appeared very inhomogeneous as the grains deformed in bands; there were also bands of grains that had very little to no deformation. From the work hardening plots it was found that an unrecrystallized, (110)<112> textured grain structure with a homogeneous distribution of subgrains produced the highest rate of work hardening between 300 K and 77 K. When the microconstituents are added to both grain structures, both the work hardening rate in the elastic-plastic and fully plastic regimes and the level of work hardening at which the elastic-plastic to fully plastic transition occurred were affected.

  6. 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.

  7. Cold Nuclear Matter Effects on J/? Yields as a Function of Rapidity and Nuclear Geometry in d+A Collisions at sNN=200GeV

    NASA Astrophysics Data System (ADS)

    Adare, A.; Afanasiev, S.; Aidala, C.; Ajitanand, N. N.; Akiba, Y.; Al-Bataineh, H.; Alexander, J.; Angerami, A.; Aoki, K.; Apadula, N.; Aphecetche, L.; Aramaki, Y.; Asai, J.; Atomssa, E. T.; Averbeck, R.; Awes, T. C.; Azmoun, B.; Babintsev, V.; Bai, M.; Baksay, G.; Baksay, L.; Baldisseri, A.; Barish, K. N.; Barnes, P. D.; Bassalleck, B.; Basye, A. T.; Bathe, S.; Batsouli, S.; Baublis, V.; Baumann, C.; Bazilevsky, A.; Belikov, S.; Belmont, R.; Bennett, R.; Berdnikov, A.; Berdnikov, Y.; Bhom, J. H.; Bickley, A. A.; Blau, D. S.; Boissevain, J. G.; Bok, J. S.; Borel, H.; Boyle, K.; Brooks, M. L.; Buesching, H.; Bumazhnov, V.; Bunce, G.; Butsyk, S.; Camacho, C. M.; Campbell, S.; Caringi, A.; Chang, B. S.; Chang, W. C.; Charvet, J.-L.; Chen, C.-H.; Chernichenko, S.; Chi, C. Y.; Chiu, M.; Choi, I. J.; Choi, J. B.; Choudhury, R. K.; Christiansen, P.; Chujo, T.; Chung, P.; Churyn, A.; Chvala, O.; Cianciolo, V.; Citron, Z.; Cole, B. A.; Conesa Del Valle, Z.; Connors, M.; Constantin, P.; Csanád, M.; Csörg?, T.; Dahms, T.; Dairaku, S.; Danchev, I.; Das, K.; Datta, A.; David, G.; Dayananda, M. K.; Denisov, A.; D'Enterria, D.; Deshpande, A.; Desmond, E. J.; Dharmawardane, K. V.; Dietzsch, O.; Dion, A.; Donadelli, M.; Drapier, O.; Drees, A.; Drees, K. A.; Dubey, A. K.; Durham, J. M.; Durum, A.; Dutta, D.; Dzhordzhadze, V.; D'Orazio, L.; Edwards, S.; Efremenko, Y. V.; Ellinghaus, F.; Engelmore, T.; Enokizono, A.; En'Yo, H.; Esumi, S.; Eyser, K. O.; Fadem, B.; Fields, D. E.; Finger, M.; Finger, M., Jr.; Fleuret, F.; Fokin, S. L.; Fraenkel, Z.; Frantz, J. E.; Franz, A.; Frawley, A. D.; Fujiwara, K.; Fukao, Y.; Fusayasu, T.; Garishvili, I.; Glenn, A.; Gong, H.; Gonin, M.; Gosset, J.; Goto, Y.; Granier de Cassagnac, R.; Grau, N.; Greene, S. V.; Grim, G.; Grosse Perdekamp, M.; Gunji, T.; Gustafsson, H.-Å.; Hadj Henni, A.; Haggerty, J. S.; Hahn, K. I.; Hamagaki, H.; Hamblen, J.; Han, R.; Hanks, J.; Hartouni, E. P.; Haruna, K.; Haslum, E.; Hayano, R.; He, X.; Heffner, M.; Hemmick, T. K.; Hester, T.; Hill, J. C.; Hohlmann, M.; Holzmann, W.; Homma, K.; Hong, B.; Horaguchi, T.; Hornback, D.; Huang, S.; Ichihara, T.; Ichimiya, R.; Iinuma, H.; Ikeda, Y.; Imai, K.; Imrek, J.; Inaba, M.; Isenhower, D.; Ishihara, M.; Isobe, T.; Issah, M.; Isupov, A.; Ivanischev, D.; Iwanaga, Y.; Jacak, B. V.; Jia, J.; Jiang, X.; Jin, J.; Johnson, B. M.; Jones, T.; Joo, K. S.; Jouan, D.; Jumper, D. S.; Kajihara, F.; Kametani, S.; Kamihara, N.; Kamin, J.; Kang, J. H.; Kapustinsky, J.; Karatsu, K.; Kasai, M.; Kawall, D.; Kawashima, M.; Kazantsev, A. V.; Kempel, T.; Khanzadeev, A.; Kijima, K. M.; Kikuchi, J.; Kim, A.; Kim, B. I.; Kim, D. H.; Kim, D. J.; Kim, E.; Kim, E. J.; Kim, S. H.; Kim, Y.-J.; Kinney, E.; Kiriluk, K.; Kiss, Á.; Kistenev, E.; Klay, J.; Klein-Boesing, C.; Kochenda, L.; Komkov, B.; Konno, M.; Koster, J.; Kozlov, A.; Král, A.; Kravitz, A.; Kunde, G. J.; Kurita, K.; Kurosawa, M.; Kweon, M. J.; Kwon, Y.; Kyle, G. S.; Lacey, R.; Lai, Y. S.; Lajoie, J. G.; Layton, D.; Lebedev, A.; Lee, D. M.; Lee, J.; Lee, K. B.; Lee, K. S.; Lee, T.; Leitch, M. J.; Leite, M. A. L.; Lenzi, B.; Li, X.; Lichtenwalner, P.; Liebing, P.; Linden Levy, L. A.; Liška, T.; Litvinenko, A.; Liu, H.; Liu, M. X.; Love, B.; Lynch, D.; Maguire, C. F.; Makdisi, Y. I.; Malakhov, A.; Malik, M. D.; Manko, V. I.; Mannel, E.; Mao, Y.; Mašek, L.; Masui, H.; Matathias, F.; McCumber, M.; McGaughey, P. L.; McGlinchey, D.; Means, N.; Meredith, B.; Miake, Y.; Mibe, T.; Mignerey, A. C.; Mikeš, P.; Miki, K.; Milov, A.; Mishra, M.; Mitchell, J. T.; Mohanty, A. K.; Moon, H. J.; Morino, Y.; Morreale, A.; Morrison, D. P.; Moukhanova, T. V.; Mukhopadhyay, D.; Murakami, T.; Murata, J.; Nagamiya, S.; Nagle, J. L.; Naglis, M.; Nagy, M. I.; Nakagawa, I.; Nakamiya, Y.; Nakamura, K. R.; Nakamura, T.; Nakano, K.; Nam, S.; Newby, J.; Nguyen, M.; Nihashi, M.; Niita, T.; Nouicer, R.; Nyanin, A. S.; Oakley, C.; O'Brien, E.; Oda, S. X.; Ogilvie, C. A.; Oka, M.; Okada, K.; Onuki, Y.; Oskarsson, A.; Ouchida, M.; Ozawa, K.; Pak, R.; Palounek, A. P. T.; Pantuev, V.; Papavassiliou, V.; Park, I. H.; Park, J.; Park, S. K.; Park, W. J.; Pate, S. F.; Pei, H.; Peng, J.-C.; Pereira, H.; Peresedov, V.; Peressounko, D. Yu.; Petti, R.; Pinkenburg, C.; Pisani, R. P.; Proissl, M.; Purschke, M. L.; Purwar, A. K.; Qu, H.; Rak, J.; Rakotozafindrabe, A.; Ravinovich, I.; Read, K. F.; Rembeczki, S.; Reygers, K.; Riabov, V.; Riabov, Y.; Richardson, E.; Roach, D.; Roche, G.; Rolnick, S. D.; Rosati, M.; Rosen, C. A.; Rosendahl, S. S. E.; Rosnet, P.; Rukoyatkin, P.; Ruži?ka, P.; Rykov, V. L.; Sahlmueller, B.; Saito, N.; Sakaguchi, T.; Sakai, S.; Sakashita, K.; Samsonov, V.; Sano, S.; Sato, T.; Sawada, S.; Sedgwick, K.; Seele, J.; Seidl, R.; Semenov, A. Yu.; Semenov, V.; Seto, R.; Sharma, D.; Shein, I.; Shibata, T.-A.; Shigaki, K.

    2011-09-01

    We present measurements of J/? yields in d+Au collisions at sNN=200GeV recorded by the PHENIX experiment and compare them with yields in p+p collisions at the same energy per nucleon-nucleon collision. The measurements cover a large kinematic range in J/? rapidity (-2.2rapidity data are inconsistent with nuclear modifications that are linear or exponential in the density weighted longitudinal thickness, such as those from the final state breakup of the bound state.

  8. Effect of Dislocations on Spinodal Decomposition, Precipitation, and Age-hardening of Cu-Ti Alloy

    NASA Astrophysics Data System (ADS)

    Sato, Shigeo; Hasegawa, Akifumi; Semboshi, Satoshi; Wagatsuma, Kazuaki

    2015-04-01

    In age-hardenable Cu-Ti alloys, cold work before aging enhances their mechanical properties and shortens the aging time for obtaining the maximum hardness. In order to discuss hardening behaviors, microstructural evolutions such as dislocation rearrangements, progress of spinodal decomposition, and subsequent precipitation from the spinodal region during aging need to be analyzed precisely. Therefore, we employed a probing method combining the small- and the wide-angle X-ray scattering methods to characterize the precipitate size and the progress of spinodal decomposition, respectively. Sideband peaks appearing adjacent to Bragg reflection peaks in the X-ray diffraction patterns of a copper matrix were analyzed to estimate the development of compositional modulations of titanium accompanied by spinodal decomposition. The results of these analytical procedures revealed that the growth rates of the spinodal region and nanometer-scales precipitates in Cu-Ti alloys are less susceptible to dislocations introduced during cold working before aging, and that dislocations introduced during prior cold working annihilate in the initial aging stage. Consequently, overaging, which is mainly induced by dislocation annihilation, in a cold-worked Cu-Ti alloy occurs after a shorter aging time than in an unworked alloy.

  9. Athermal Solid Solution Hardening in Tantalum

    NASA Astrophysics Data System (ADS)

    Gypen, L. A.; Deruyttere, A.

    1982-06-01

    The influence of solute atoms on the athermal component of the flow stress, determined by means of dip-tests (incremental unloading), has been investigated at room temperature and slightly above in binary Ta-Re, Ta-Mo, Ta-W, Ta-Hf, Ta-Zr, and Ta-Nb alloys and in ternary Ta-W-Re, Ta-W-Mo, Ta-W-Hf, and Ta-W-Nb alloys. Binary athermal substitutional solid solution hardening in tantalum is linear up to high concentrations of solute and is dominated by the atomic size misfit parameter, in agreement with the authors’ recent model for binary athermal solid solution hardening in bcc metals at temperatures where the Peierls stress is still important. In this model, solid solution hardening is caused by interactions of solute atoms having a size misfit with polarity reversing kinks and constrictions in <111> screw dislocations. The observed solid solution hardening in the ternary alloys is well described by the authors’ phenomenological model for multicomponent solid solution hardening.

  10. Recent advances in surface hardening of titanium

    NASA Astrophysics Data System (ADS)

    Sarma, B.; Ravi Chandran, K. S.

    2011-02-01

    Titanium and its alloys are used significantly in defense, aerospace and biomedical device components. However, their poor wear resistance and surface integrity leads to galling and seizure of surfaces when contact or relative motions of surfaces are involved. Surface hardening of Ti is therefore actively pursued to minimize the wear and fretting of components in these applications. The purpose of this review is to highlight some of the recent advances in surface hardening of Ti and its alloys, especially by diffusion of interstitial elements such as nitrogen, oxygen, and boron. These interstitial elements react with Ti to form hard and wear resistant compound layers at the surface and thereby, enhance the wear/abrasion properties. The recent developments pertaining to these surface hardening techniques in terms of the process parameters, microstructural details and enhancement in mechanical/wear properties are summarized in this review.

  11. 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.

  12. 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).

  13. 7 CFR 58.622 - Hardening and storage rooms.

    Code of Federal Regulations, 2014 CFR

    2014-01-01

    ...Compartments § 58.622 Hardening and storage rooms. Hardening and storage rooms for frozen desserts shall be constructed of satisfactory material for this purpose. The rooms shall be maintained in a clean and orderly manner. Adequate...

  14. 7 CFR 58.622 - Hardening and storage rooms.

    Code of Federal Regulations, 2013 CFR

    2013-01-01

    ...Compartments § 58.622 Hardening and storage rooms. Hardening and storage rooms for frozen desserts shall be constructed of satisfactory material for this purpose. The rooms shall be maintained in a clean and orderly manner. Adequate...

  15. 7 CFR 58.622 - Hardening and storage rooms.

    Code of Federal Regulations, 2012 CFR

    2012-01-01

    ...Compartments § 58.622 Hardening and storage rooms. Hardening and storage rooms for frozen desserts shall be constructed of satisfactory material for this purpose. The rooms shall be maintained in a clean and orderly manner. Adequate...

  16. Orowan strengthening and forest hardening superposition examined by dislocation dynamics simulations

    E-print Network

    Devincre, Benoit

    Orowan strengthening and forest hardening superposition examined by dislocation dynamics- hardening mechanism is involved. In this work, use is made of dislocation dynamics simulations.e. Orowan strengthening and forest hardening. Based on a formal description of each hardening mechanism

  17. Spectral Hardening of Large Solar Flares

    E-print Network

    Paolo C. Grigis; Arnold O. Benz

    2008-05-01

    RHESSI observations are used to quantitatively study the hard X-ray evolution in 5 large solar flares selected for spectral hardening in the course of the event. The X-ray bremsstrahlung emission from non-thermal electrons is characterized by two spectroscopically distinct phases: impulsive and gradual. The impulsive phase usually consists of several emission spikes following a soft-hard-soft spectral pattern, whereas the gradual stage manifests itself as spectral hardening while the flux slowly decreases. Both the soft-hard-soft (impulsive) phase and the hardening (gradual) phase are well described by piecewise linear dependence of the photon spectral index on the logarithm of the hard X-ray flux. The different linear parts of this relation correspond to different rise and decay phases of emission spikes. The temporal evolution of the spectra is compared with the configuration and motion of the hard X-ray sources in RHESSI images. These observations reveal that the two stages of electron acceleration causing these two different behaviors are closely related in space and time. The transition between the impulsive and gradual phase is found to be smooth and progressive rather than abrupt. This suggests that they arise because of a slow change in a common accelerator rather than being caused by two independent and distinct acceleration processes. We propose that the hardening during the decay phase is caused by continuing particle acceleration with longer trapping in the accelerator before escape.

  18. 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

  19. Challenges in hardening technologies using shallow-trench isolation

    Microsoft Academic Search

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

    1998-01-01

    Challenges related to radiation hardening CMOS technologies with shallow-trench isolation are explored. It is shown that developing a radiation-hardened CMOS technology with shallow trench isolation is more complex than using a traditional hardened field oxide as the trench insulator. We illustrate the use of device simulations in concert with measurements on test structures to provide detailed physical insight into methods

  20. 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.

  1. Theoretical and experimental analysis of high power diode laser (HPDL) hardening of AISI 1045 steel

    NASA Astrophysics Data System (ADS)

    Lusquiños, F.; Conde, J. C.; Bonss, S.; Riveiro, A.; Quintero, F.; Comesaña, R.; Pou, J.

    2007-12-01

    Laser surface hardening makes use of the rapid and cooling cycles produced on metals surfaces exposed to a scanning laser beam without affecting the bulk of the sample. Mechanical and chemical properties of the surface can be enhanced through the metallurgical transformations that take place during the mentioned thermal cycles. Steels and cast irons are the usual materials to be hardened by laser and recently the high power diode lasers (HPDL) became the appropriate tool to carry out this process. In this work, some systematic experiments have been carried out to harden AISI 1045 surface samples by a cw (HPDL) working at different power levels (470, 760 W). The main processing parameters (scanning velocity and density power of the laser beam) were tuned from the prediction realized by the numerical (ANSYS) analysis of the heat conduction involved in the process. Such analysis allowed us to put in evidence the variation of the temperature and the cooling rate of the steel sample surface, affecting the uniformity of the demanding mechanical properties of the surface. In this way, a close-loop temperature control of the surface was justified in order to keep the hardness value within the range required. The formation of martensite phase in the laser treated superficial zone confirmed the hardening of the steel.

  2. Terminal modeling of hardened integrated circuits

    NASA Astrophysics Data System (ADS)

    Kleiner, C. T.; Haas, R.; Peacock, M.; Mandel, G.; Messenger, G. C.; Weakley, D.; Demartino, V.

    1981-12-01

    Kleiner et al. (1979) have reported modeling and test verification techniques used to develop medium-scale, dielectrically isolated integrated circuits (DIIC). The current investigation is concerned with the approaches employed in modeling the new circuits for applications studied by design and radiation hardening engineers. The described technique improves significantly the cost-effective application of computer programs such as SYSCAP II. The terminal model offers the designer of radiation-hardened electronic circuits a method for evaluating the effects of radiation transients on single or multiple piece-part response at the circuit board level. Although the models presented were intended for TREE design and analysis, it is possible to extend the technique to EMP and SGEMP evaluations.

  3. Memento: A Framework for Hardening Web Applications

    Microsoft Academic Search

    Karthick Jayaraman; Grzegorz Lewandowski; Steve J. Chapin

    2008-01-01

    We propose a generic framework called Memento for systemati cally hardening web applications. Memento models a web application's behavior using a deterministic finite automata (DFA), where each server-side script is a state, and st ate transitions are triggered by HTTP requests. We use this DFA t o defend against cross-site request forgery (CSRF) and cros s- site-scripting (XSS) attacks. The

  4. Mercury porosimetry of hardened cement pastes

    Microsoft Academic Search

    Raymond A. Cook; Kenneth C. Hover

    1999-01-01

    Mercury porosimetry was performed on 92 hardened cement paste specimens of water\\/cement (w\\/c) ratios 0.3, 0.4, 0.5, 0.6, and 0.7 and curing times of 1, 3, 7, 14, 28, and 56 days. This paper presents the experimental techniques, results, and their possible implications with respect to pore connectivity. As expected, longer curing times and lower w\\/c ratios resulted in smaller

  5. Common Cold

    MedlinePLUS

    ... en español] National Library of Medicine, Medline Plus ? Common Cold Skip Content Marketing Share this: JavaScript is disabled in your browser. To view this content, please enable JavaScript and refresh the page. Click here for instructions on how to enable JavaScript in your browser. ...

  6. Cold Sores

    MedlinePLUS

    ... causes oral herpes, or cold sores. Type 1 herpes virus infects more than half of the U.S. population by the time they reach their 20s. Type 2 usually affects the genital area Some people have no symptoms from the ...

  7. Cold War

    NSDL National Science Digital Library

    Cold War is a major, 24-part series directed by renowned documentary filmmaker Jeremy Isaacs that recently premiered on CNN and BBC2. Whether or not this series will become "the definitive account of the Cold War" remains to be seen, but the research that has made it possible is quite impressive. This feature-filled, comprehensive site complements the series by offering, among other things, video previews and multimedia recaps of each episode; video, audio, and text excerpts from nearly 100 interviews filmed for the series; text from archival documents and contemporaneous Time and Russian newspaper stories; in-depth sections on Cold War culture; and a Knowledge Bank section containing a glossary, "Cold Warrior" profiles, related links, and a chronology. Additional resources include a classroom guide to the series, online Shockwave quiz games, and an online discussion group. As large as it is now, the site will continue to expand and add new features as the series progresses over the next three months.

  8. 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.

  9. Strain hardening in underaged INCONEL 718

    SciTech Connect

    Sundararaman, M.; Kishore, R.; Mukhopadhyay, P. (Bhabha Atomic Research Centre, Bombay (India))

    1994-03-01

    INCONEL 718 is a commercial, precipitation-hardenable nickel iron-base superalloy, strengthened primarily by precipitates of the metastable [gamma][double prime] phase which is based on the composition Ni[sub 3]Nb and has an ordered body-centered tetragonal (DO[sub 22]) structure. An earlier investigation on the deformation mechanisms in this alloy has shown that [gamma][double prime] precipitates are sheared by the passage of true crystallographic twins (which do not destroy the ordered atomic arrangements within precipitate crystals) when the [gamma][double prime] particle size is larger than about 10 nm. In a situation where the precipitate size is smaller than about 10 nm, the deformation occurs by the passage of quadruplets or pairs of dislocations which shear the [gamma][double prime] particles. The change in the deformation mechanism from dislocation cutting to twinning with increasing [gamma][double prime] particle size is reflected in a drop in the value of the Croussard-Jaoul work-hardening exponent (from 0.8 to 0.5) which has been attributed to the easy propagation of deformation twins within the particles. The present communication reports the results of a study carried out on the characterization of the deformation microstructure of underaged INCONEL 718. An attempt has been made to explain the work-hardening behavior of the alloy in the light of transmission electron microscopic (TEM) observations on its deformation microstructures in the underaged condition.

  10. Empirical beam hardening correction (EBHC) for CT

    SciTech Connect

    Kyriakou, Yiannis; Meyer, Esther; Prell, Daniel; Kachelriess, Marc [Institute of Medical Physics, University of Erlangen-Nuernberg, 91052 Erlangen (Germany)

    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 C-arm CT scanner (Axiom Artis dTA, Siemens Healthcare, Forchheim, Germany). A large variety of phantom, small animal, and patient data were used to demonstrate the data and system independence of EBHC. Results: Although no physics apart from the initial segmentation procedure enter the correction process, beam hardening artifacts were significantly reduced by EBHC. The image quality for clinical CT, micro-CT, and C-arm CT was highly improved. Only in the case of C-arm CT, where high scatter levels and calibration errors occur, the relative improvement was smaller. Conclusions: The empirical beam hardening correction is an interesting alternative to conventional iterative higher order beam hardening correction algorithms. It does not tend to over- or undercorrect the data. Apart from the segmentation step, EBHC does not require assumptions on the spectra or on the type of material involved. Potentially, it can therefore be applied to any CT image.

  11. Laser quench hardening of steel: Effects of superimposed elastic pre-stress on the hardness and residual stress distribution

    NASA Astrophysics Data System (ADS)

    Meserve, Justin

    Cold drawn AISI 4140 beams were LASER surface hardened with a 2 kW CO2 LASER. Specimens were treated in the free state and while restrained in a bending fixture inducing surface tensile stresses of 94 and 230 MPa. Knoop hardness indentation was used to evaluate the through thickness hardness distribution, and a layer removal methodology was used to evaluate the residual stress distribution. Results showed the maximum surface hardness attained was not affected by pre-stress during hardening, and ranged from 513 to 676 kg/mm2. The depth of effective hardening varied at different magnitudes of pre-stress, but did not vary proportionately to the pre-stress. The surface residual stress, coinciding with the maximum compressive residual stress, increased as pre-stress was increased, from 1040 MPa for the nominally treated specimens to 1270 MPa for specimens pre-stressed to 230 MPa. The maximum tensile residual stress observed in the specimens decreased from 1060 MPa in the nominally treated specimens to 760 MPa for specimens pre-stressed to 230 MPa. Similarly, thickness of the compressive residual stress region increased and the depth at which maximum tensile residual stress occurred increased as the pre-stress during treatment was increased Overall, application of tensile elastic pre-stress during LASER hardening is beneficial to the development of compressive residual stress in AISI 4140, with minimal impact to the hardness attained from the treatment. The newly developed approach for LASER hardening may support efforts to increase both the wear and fatigue resistance of parts made from hardenable steels.

  12. Cold agglutination.

    PubMed

    Roelcke, D

    1989-04-01

    Autoantibodies against red cells optimally reacting at 0 degree C, ie, CA, are normally found with low titers in the serum of human adults. High-titer CA may be induced by certain infectious agents, including M pneumoniae, EBV, CMV, and rubella virus, or may develop on the basis of chronic (malignant) B cell lymphoproliferation. The main clinical manifestation of cold agglutination is AIHA. Antigens and antibodies of cold agglutination are the best characterized reaction partners of a human autoimmune process. CA may recognize I and i antigens, which are lipid- and protein-linked branched and linear N-acetyl-lactosamine chains, respectively. They are precursors of the ABH blood group antigens and are converted into H by fucosylation. An alternative substitution by sialylation creates Gd, Fl, and probably Vo/Li antigens. CA with anti-Pr and anti-Sa specificities recognize 0-glycans with immunodominant sialyl groups on glycophorins. Several Pr subspecificities can be identified by chemically modified sialyl groups on glycophorins. Because CA in chronic lymphoproliferation are monoclonal antibodies, structure-specificity-interrelations of the antibodies could be identified by primary structure analyses of the N-terminal variable regions of H and L chains and by studies on CA idiotypes. Interrelations between distinct CA specificities and particular infectious agents could explain cold agglutination as a response to receptors for the agents or to the binding sites of antibodies against the agents. Interrelations also existing between certain CA isotypes (Ig classes and L chain types) and CA specificities could be a basis for the elucidation of the enigmatic etiology of chronic (malignant) monoclonal cold agglutination. PMID:2520550

  13. Radiation-hardened N (+) gate CMOS\\/SOS

    Microsoft Academic Search

    G. W. Hughes; G. J. Brucker; R. K. Smeltzer

    1981-01-01

    Process development work for a hardened N+ polysilicon-gate CMOS\\/SOS process has demonstrated that it is possible to make functional 4K CMOS\\/SOS static RAMs that are hard to 5 x 10 to the 5th power rads without the implementation of special hardened circuit design techniques. Present circuit probe yields are low, limited by the lack of a hardened low-temperature contoured field

  14. Comparison of elastic—plastic fracture toughness of irradiated and cold-worked JPCA using miniaturized DCT specimens

    NASA Astrophysics Data System (ADS)

    Jitsukawa, Shiro; Shiba, Kiyoyuki; Hishinuma, Akimichi; Alexander, David J.; Pawel, Janet E.

    1996-10-01

    J—R curves of an austenitic stainless steel in solution annealed and cold worked conditions were obtained using miniaturized fracture toughness specimens and standard compact tension specimens. Results indicate that the specimen size effect for the cold worked steel was small. JQ values of irradiated miniaturized specimens agreed well with those of cold worked specimens with similar yield stress levels. This suggests that the irradiation induced degradation of the fracture toughness is mainly dependent upon the irradiation hardening.

  15. Cold Stowage Flight Systems

    NASA Technical Reports Server (NTRS)

    Campana, Sharon E.; Melendez, David T.

    2011-01-01

    The International Space Station (ISS) provides a test bed for researchers to perform science experiments in a variety of fields, including human research, life sciences, and space medicine. Many of the experiments being conducted today require science samples to be stored and transported in a temperature controlled environment. NASA provides several systems which aid researchers in preserving their science. On orbit systems provided by NASA include the Minus Eighty Laboratory freezer for ISS (MELFI), Microgravity Experiment Research Locker Incubator (MERLIN), and Glacier. These freezers use different technologies to provide rapid cooling and cold stowage at different temperature levels on board ISS. Systems available to researchers during transportation to and from ISS are MERLIN, Glacier, and Coldbag. Coldbag is a passive cold stowage system that uses phase change materials to maintain temperature. Details of these current technologies are provided along with operational experience gained to date. This paper discusses the capability of the current cold stowage hardware and how it may continue to support NASA s mission on ISS and in future exploration missions.

  16. Cold Stowage Flight Systems

    NASA Technical Reports Server (NTRS)

    Campana, Sharon

    2010-01-01

    The International Space Station (ISS) provides a test bed for researchers to perform science experiments in a variety of fields, including human research, life sciences, and space medicine. Many of the experiments being conducted today require science samples to be stored and transported in a temperature controlled environment. NASA provides several systems which aide researchers in preserving their science. On orbit systems provided by NASA include the Minus Eighty Laboratory freezer for ISS (MELFI), Microgravity Experiment Research Locker Incubator (MERLIN), and Glacier. These freezers use different technologies to provide rapid cooling and cold stowage at different temperature levels on board ISS. Systems available to researchers during transportation to and from ISS are MERLIN, Glacier, and Coldbag. Coldbag is a passive cold stowage system that uses phase change materials. Details of these current technologies will be provided along with operational experience gained to date. With shuttle retirement looming, NASA has protected the capability to provide a temperature controlled environment during transportation to and from the ISS with the use of Glacier and Coldbags, which are compatible with future commercial vehicles including SpaceX's Dragon Capsule, and Orbital s Cygnus vehicle. This paper will discuss the capability of the current cold stowage hardware and how it may continue to support NASA s mission on ISS and in future exploration missions.

  17. Hologram formation in hardened dichromated gelatin films.

    PubMed

    Lin, L H

    1969-05-01

    Hardened gelatin films sensitized with ammonium dichromate can be utilized to record high quality holograms. The maximum diffraction efficiency of the hologram approaches 90%. The light scattering from the hologram is so low that under ordinary light the hologram plate appears almost indistinguishable from a clear glass plate. Either a transmission or a reflection hologram can be recorded. Linear recording range of light amplitude is large. A practical method of preparing and processing the film is described, and the exposure characteristics are presented. PMID:20072355

  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. Sulfate attack on hardened cement paste

    SciTech Connect

    Wang, J.G. (Shenzhen Univ. (China). Dept. of Applied Chemistry)

    1994-01-01

    Hardened cement paste specimens made with different cement types and varying water-cement ratios (w/c) were immersed in 5% sodium sulfate solution maintained at constant pH value of 6. The distribution curves for ettringite, gypsum, and portlandite phases were obtained by using layer by layer XRD analysis and interpreted in terms of material damage due to sulfate attack. The mechanism of sulfate attack is evaluated in regard to the leaching of Ca(OH)[sub 2] and formation of gypsum and ettringite.

  20. Beam hardening and partial beam hardening of the bowtie filter: Effects on dosimetric applications in CT

    NASA Astrophysics Data System (ADS)

    Lopez-Rendon, X.; Zhang, G.; Bosmans, H.; Oyen, R.; Zanca, F.

    2014-03-01

    Purpose: To estimate the consequences on dosimetric applications when a CT bowtie filter is modeled by means of full beam hardening versus partial beam hardening. Method: A model of source and filtration for a CT scanner as developed by Turner et. al. [1] was implemented. Specific exposures were measured with the stationary CT X-ray tube in order to assess the equivalent thickness of Al of the bowtie filter as a function of the fan angle. Using these thicknesses, the primary beam attenuation factors were calculated from the energy dependent photon mass attenuation coefficients and used to include beam hardening in the spectrum. This was compared to a potentially less computationally intensive approach, which accounts only partially for beam hardening, by giving the photon spectrum a global (energy independent) fan angle specific weighting factor. Percentage differences between the two methods were quantified by calculating the dose in air after passing several water equivalent thicknesses representative for patients having different BMI. Specifically, the maximum water equivalent thickness of the lateral and anterior-posterior dimension and of the corresponding (half) effective diameter were assessed. Results: The largest percentage differences were found for the thickest part of the bowtie filter and they increased with patient size. For a normal size patient they ranged from 5.5% at half effective diameter to 16.1% for the lateral dimension; for the most obese patient they ranged from 7.7% to 19.3%, respectively. For a complete simulation of one rotation of the x-ray tube, the proposed method was 12% faster than the complete simulation of the bowtie filter. Conclusion: The need for simulating the beam hardening of the bow tie filter in Monte Carlo platforms for CT dosimetry will depend on the required accuracy.

  1. Plastic substrate hardening by PE-CVD

    NASA Astrophysics Data System (ADS)

    Menichella, Stefania; Misiano, Carlo; Simonetti, Enrico; De Carlo, L.

    1994-09-01

    The usage of plastic substrates has known a big enhancement driven by ophthalmic applications, but a further spreading can be foreseen in higher technological fields too. As known, two drawbacks are outlined when using these substrate: low scratching resistance; high thermal expansion coefficient, thus bad compatibility with the optical coatings made of inorganic layers. The most widespread solution up to now is a hardening and mechanical matching lacquer coating by dipping, which is well accepted in ophthalmics, but cannot be utilized in precision optics due to its intrinsic thickness disuniformity. Recently similar layers have been realized by Plasma Enhanced Chemical Vapor Deposition. This paper describes Ce.Te.V.'s activities and results in setting up this coating by RF PE-CVD, aimed to both ophthalmics and precision optics. The two different functions (hardening and mechanical matching) and the performances of the coating-with special attention to scratch and thermal shock resistance-are examined. The experimental equipment and the optical and environmental characteristics are described.

  2. 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.

  3. Common cold

    PubMed Central

    2011-01-01

    Introduction Each year, children suffer up to 5 colds and adults have two to three infections, leading to time off school or work, and considerable discomfort. Most symptoms resolve within 1 week, but coughs often persist for longer. Methods and outcomes We conducted a systematic review and aimed to answer the following clinical question: What are the effects of treatments for common cold? We searched: Medline, Embase, The Cochrane Library, and other important databases up to January 2010 (Clinical Evidence reviews are updated periodically, please check our website for the most up-to-date version of this review). We included harms alerts from relevant organisations such as the US Food and Drug Administration (FDA) and the UK Medicines and Healthcare products Regulatory Agency (MHRA). Results We found 21 systematic reviews and RCTs that met our inclusion criteria. We performed a GRADE evaluation of the quality of evidence for interventions. Conclusions In this systematic review we present information relating to the effectiveness and safety of the following interventions: analgesics or anti-inflammatory drugs, antibiotics, antihistamines, decongestants for short-term and for long-term relief, decongestants plus antihistamines, echinacea, steam inhalation, vitamin C, and zinc (intranasal gel or lozenges). PMID:21406124

  4. Cold worked high alloy ultra-high strength steels with aged martensite structure

    Microsoft Academic Search

    S. J. Pawlak; H. J. Krzto?

    Purpose: The study on structure-property relations of heavily cold worked and aged martensite in two high- alloy structural steels was presented. The aim was to understand properties of the sheet products better and thus extend applications of the newly developed cobalt-free maraging and precipitation hardening stainless steels. Design\\/methodology\\/approach: Mechanical tests were performed on cold rolled and aged specimens. Microstructures were

  5. Modeling the strain hardening response of low SFE FCC alloys

    Microsoft Academic Search

    Surya R. Kalidindi

    1998-01-01

    A mathematical description has been proposed to capture the complex four-stage strain hardening behavior of low stacking fault energy (SFE) polycrystalline fcc metallic alloys that deform plastically by both slip and twinning mechanisms. It has been demonstrated that the proposed model is capable of predicting fairly accurately the measurements reported previously on the strain-hardening responses of several fcc alloys, including

  6. Radiation hardening of a high voltage IC technology (BCDMOS)

    SciTech Connect

    Desko, J.C. Jr.; Darwish, M.N.; Dolly, M.C.; Goodwin, C.A. (AT and T Bell Lab., Reading, PA (US)); Dawes, W.R. Jr. (Sandia National Labs., Albuquerque, NM (USA)); Titus, J.L. (Naval Weapons Support Center, Crane, IN (USA))

    1990-12-01

    A program was undertaken to radiation harden an existing power integrated circuit technology (BCDMOS) to total dose, gamma dot, SEU, and neutrons. Efforts have centered around hardening and optimizing our CMOS, DMOS, and NPN devices. Initial results indicate a substantial improvement in hardness over our existing commercial technology.

  7. High-strength age hardening coppertitanium alloys: redivivus

    E-print Network

    Laughlin, David E.

    High-strength age hardening copper­titanium alloys: redivivus W.A. Soffaa , D.E. Laughlinb by an anticipated emergence of these alloys as technologi- cally significant high-strength, high-conductivity, precipitation hardened alloys over the next decade replacing conventional Cu­Be alloys in numerous applications

  8. 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.

  9. Plant pathology Influence of pre-hardening duration and dehardening

    E-print Network

    Paris-Sud XI, Université de

    freezing resistance in faba beans ( Vicia faba L.) H. Herzog Institute of Crop Science and Plant Breeding — Hardening response of winter faba beans at 8/2°C (day/night) to pre-hardening periods at 15°C - differential leaf response - winter beans - !cia faba L. Résumé — L'influence de la durée de la phase

  10. WELDING PROPERTIES OF CHROMIUM-NICKEL-MOLYBDENUM HARDENABLE STAINLESS STEELS

    Microsoft Academic Search

    Kaltenhauser

    1959-01-01

    BS>Semiaustenitic hardenable stainless steels types AM-350 and AM-355 ; were found to have excellent weldability by the same techniques and processes ; that are used for austenitic stainiess steels. By appropriate low-temperature ; postweld heat treatments, the weld and base metals may be transformed to a high-; strength tempered martensitic structure. Both alloys have welded and hardened ; strengths equal

  11. Microstructural Evolution and Age Hardening in Aluminium Alloys

    Microsoft Academic Search

    S. P. Ringer; K. Hono

    2000-01-01

    This paper examines the microstructural evolution in selected aluminium alloys based on commercial age hardenable 2000, 6000, and 7000 series alloys. Atom probe field-ion microscopy and transmission electron microscopy have been used to examine the effects of microalloying and the origins of hardening. The combined application of these techniques is particularly important in the study of nanoscale precipitation processes. It

  12. A Novel High-Density Single-Event Upset Hardened Configurable SRAM Applied to FPGA

    Microsoft Academic Search

    Lei Wang; Lei Chen; Zhiping Wen; Huabo Sun; Shuo Wang

    2009-01-01

    This paper has investigated present radiation hardened FPGA manufacturers and SEU hardened method of configurable SRAM (CSRAM) applied to FPGA. A novel high-density single-event upset hardened CSRAM applied to BQV 300 FPGA is proposed, and this paper uses the mix-mode radiation hardened verification method to simulate the SEU hardened CSRAM. The proposed SEU-hardened CSRAM applied to FPGAs is SEU immune

  13. Investigation of Secondary Hardening in Co-35Ni--20Cr--10Mo Alloy Using Analytical Scanning Transmission Electron Microscopy

    NASA Astrophysics Data System (ADS)

    Sorensen, Daniel David

    The mechanism of secondary hardening in MP35N (Co--35Ni--20Cr--10Mo) alloy due to exposures at elevated temperatures has been studied. It was observed that short exposure to elevated temperatures increased the ultimate tensile strength and yield stress while decreasing the elongation of MP35N wires. Upon aging at temperatures from 300 to 900°C the elastic modulus increased although no changes in crystallographic orientation or microstructure were observed. No proposed model for this apparent increase in elastic modulus is suggested as yet. The grain size and major texture components were unchanged following aging. Analytical scanning transmission electron microscope investigation showed that MP35N is hardened by preferential segregation of molybdenum to stacking faults and deformation twins. It also revealed that the concentration of molybdenum segregation was proportional to the amount of initial cold work before aging.

  14. Design Features and Initial RF Performance of a Gradient Hardened 17 GHz TW Linac Structure

    SciTech Connect

    Haimson, J.; Mecklenburg, B. [Haimson Research Corporation 3350 Scott Blvd., Building 60, Santa Clara, CA 95054-3104 (United States)

    2009-01-22

    To avoid surface erosion damage and to assist in studying RF breakdown thresholds in 17 GHz TW linac structures, a gradient hardened structure has been fabricated with high temperature brazed and machined stainless steel surfaces located in the peak E-field region of the beam apertures and the peak H-field regions of the input coupler cavity. The microwave design parameters and physical dimensions of this 22 cavity, 120 degree phase advance structure were chosen to allow the high gradient performance to be compared against a similar design all-copper structure that has been tested in a dual ring, power recirculating amplifier system. The final design parameters of the gradient hardened structure are discussed; the influence of stainless steel RF losses on the power buildup of the resonant ring and on the structure gradient distribution are described; waveforms are shown of the unique ability of the power amplifier to rapidly quench RF breakdown discharges in the linac structure by automatically sensing and redirecting the RF source power to a matched load; and preliminary test results during high power RF processing of the gradient hardened linac structure are presented.

  15. Effects of porosity on leaching of Ca from hardened ordinary Portland cement paste

    SciTech Connect

    Haga, Kazuko [Taiheiyo Consultant Co. Ltd., 2-4-2, Osaku, Sakura-City, Chiba 285-8655 (Japan)]. E-mail: Kazuko_Haga@grp.taiheiyo-cement.co.jp; Sutou, Shunkichi [Taiheiyo Consultant Co. Ltd., 2-4-2, Osaku, Sakura-City, Chiba 285-8655 (Japan); Hironaga, Michihiko [Central Research Institute of Electric Power Industry, 1646, Abiko, Abiko-City, Chiba 270-1194 (Japan); Tanaka, Satoru [Department of Quantum Engineering and Systems Sciences, University of Tokyo, 7-3-1, Hongo, Bunkyo-ku, Tokyo 113-8656 (Japan); Nagasaki, Shinya [Institute of Environmental Studies, Graduate School of Frontier Sciences, University of Tokyo, 7-3-1, Hongo, Bunkyo-ku, Tokyo 113-8656 (Japan)

    2005-09-01

    Aiming at evaluating the effects of porosity in hardened cement paste on dissolution phenomena, we prepared hardened ordinary Portland cement (OPC), with variation in pore volume, and then leached them in deionized water. It was found that the bulk density and pore volume were affected by the dissolution of portlandite. The larger the pore volume of the sample, the more rapidly portlandite is dissolved. An electron probe microanalysis (EPMA) performed on the cross-section of the solid phase showed the 'portlandite (CH) dissolution front'. As the leaching period became longer, the CH dissolution front shifted towards the inner part. In addition, the movement of the CH dissolution front was described by the diffusion model, with consideration of the dissolution of portlandite. It was concluded that the transport of leached constituents is diffusion controlled, and the major leached constituents of hardened OPC are portlandite and C-S-H gel. Large pore, which was generated associated with the leaching of portlandite, was considered significantly to affect the diffusion of leached constituents.

  16. Cold tolerance of the Australian spur-throated locust, Austracris guttulosa.

    PubMed

    Woodman, James D

    2012-03-01

    The cold tolerance of overwintering adult Spur-throated locusts, Austracris guttulosa, was examined using measures of supercooling point relative to gender, environmental acclimation and feeding state as well as mortality for a range of sub-zero temperature exposure treatments. Freezing was lethal and supercooling points ranged from -6 to -12.8°C, but were statistically independent of fresh mass, body water content, acclimation, and/or gut content in fed and starved individuals. A significant interaction effect of gender and feeding status showed that the larger bodied females had decreased supercooling capacity with increased food material in the digestive tract. Post-freezing dissections revealed differences in the amount of freshly consumed and retained food material in the digestive tract between fed and starved individuals of each gender, which could explain this effect based on inoculation of ice crystallisation by food particles. Above supercooling temperatures, neither gender nor the rate of cooling had a significant effect on mortality. When cooled from 25°C at 0.1 or 0.5°Cmin(-1) to a range of experimental minimum temperatures held for 3h, survival was ~74% to -7°C, but declined sharply to ~37% when cooled to -8°C or lower. Although the laboratory experiments reported here suggest that A. guttulosa is not freeze tolerant and unable to rapidly cold harden, exposure to typical cold and frosty nights that very rarely reach below -8°C as a night minimum in the field would be unlikely to cause mortality in the vast majority of overwintering aggregations. PMID:22226821

  17. Superfunctionalities in Nanodispersive Precipitation-Hardened Alloys

    NASA Astrophysics Data System (ADS)

    Rao, Wei-Feng; Khachaturyan, Armen G.

    2012-09-01

    Although nanodispersive precipitation-hardened alloys have been intensively studied over decades as important structural materials, the possibility that these alloys may have superfunctional properties has been completely overlooked. As shown in this Letter, they may have giant low-hysteretic strain responses to external stimuli if the nanosized single-domain precipitates can switch their orientation variants under applied fields. We demonstrate that the misfit-generated coherency stress can significantly reduce the variant switching barriers and may drastically decrease or even eliminate the hysteresis of the strain super responses to external stress and/or magnetic fields. These alloys can thus be functionalized as shape memory, superelastic, and/or supermagnetostrictive materials. The conditions of such functionalization are established by the interpretation-transparent analytical calculations, and confirmed by computer prototyping. In particular, the obtained results pave the way for the engineering of rare-earth free alloys with excellent magnetomechanical and good mechanical properties.

  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. Tailored work hardening descriptions in simulation of sheet metal forming

    NASA Astrophysics Data System (ADS)

    Vegter, Henk; Mulder, Hans.; van Liempt, Peter; Heijne, Jan

    2013-12-01

    In the previous decades much attention has been given on an accurate material description, especially for simulations at the design stage of new models in the automotive industry. Improvements lead to shorter design times and a better tailored use of material. It also contributed to the design and optimization of new materials. The current description of plastic material behaviour in simulation models of sheet metal forming is covered by a hardening curve and a yield surface. In this paper the focus will be on modelling of work hardening for advanced high strength steels considering the requirements of present applications. Nowadays work hardening models need to include the effect of hard phases in a soft matrix and the effect of strain rate and temperature on work hardening. Most material tests to characterize work hardening are only applicable to low strains whereas many practical applications require hardening data at relatively high strains. Therefore, physically based hardening descriptions are needed allowing reliable extensions to high strain values.

  20. Effect of low-temperature hardening on activities of proteolytic enzymes and their inhibitors in the leaves of wheat and cucumber seedlings

    Microsoft Academic Search

    S. A. Frolova; A. F. Titov; V. V. Talanova

    2011-01-01

    On seedlings of winter wheat (Triticum aestivum L.) and cucumber (Cucumis sativus L.), the dynamics of cysteine and serine trypsin-like proteinases and also trypsin inhibitors at cold hardening (5°C for\\u000a wheat and 10°C for cucumber) was studied. Activation of proteinases and inhibitors coincided in time or preceded an increased\\u000a tolerance in wheat and cucumber seedlings in the early period of

  1. Cold Atoms

    NASA Astrophysics Data System (ADS)

    Bellac, Michel Le

    2014-11-01

    This chapter and the following one address collective effects of quantum particles, that is, the effects which are observed when we put together a large number of identical particles, for example, electrons, helium-4 or rubidium-85 atoms. We shall see that quantum particles can be classified into two categories, bosons and fermions, whose collective behavior is radically different. Bosons have a tendency to pile up in the same quantum state, while fermions have a tendency to avoid each other. We say that bosons and fermions obey two different quantum statistics, the Bose-Einstein and the Fermi-Dirac statistics, respectively. Temperature is a collective effect, and in Section 5.1 we shall explain the concept of absolute temperature and its relation to the average kinetic energy of molecules. We shall describe in Section 5.2 how we can cool atoms down thanks to the Doppler effect, and explain how cold atoms can be used to improve the accuracy of atomic clocks by a factor of about 100. The effects of quantum statistics are prominent at low temperatures, and atom cooling will be used to obtain Bose-Einstein condensates at low enough temperatures, when the atoms are bosons.

  2. Cold fusion

    SciTech Connect

    Bush, R.T. (California State Polytechnic Univ., Physics Dept., Pomona, CA (US))

    1991-03-01

    The transmission resonance model (TRM) is combined with some electrochemistry of the cathode surface and found to provide a good fit to new data on excess heat. For the first time, a model for cold fusion not only fits calorimetric data but also predicts optimal trigger points. This suggests that the model is meaningful and that the excess heat phenomenon claimed by Fleischmann and Pons is genuine. A crucial role is suggested for the overpotential and, in particular, for the concentration overpotential, i.e., the hydrogen overvoltage. Self-similar geometry, or scale invariance, i.e., a fractal nature, is revealed by the relative excess power function. Heat bursts are predicted with a scale invariance in time, suggesting a possible link between the TRM and chaos theory. The model describes a near-surface phenomenon with an estimated excess power yield of {approximately}1 kW/cm{sup 3} Pd, as compared to 50 W/cm{sup 3} of reactor core for a good fission reactor. Transmission resonance-induced nuclear transmutation, a new type of nuclear reaction, is strongly suggested with two types emphasized: transmission resonance-induced neutron transfer reactions yielding essentially the same end result as Teller's hypothesized catalytic neutron transfer and a three-body reaction promoted by standing de Broglie waves. In this paper suggestions for the anomalous production of heat, particles, and radiation are given.

  3. Cold confusion

    SciTech Connect

    Chapline, G.

    1989-07-01

    On March 23 two chemists, Martin Fleischmann and Stanley Pons startled the world with a press conference at the University of Utah where they announced that they had achieved nuclear fusion at room temperatures. As evidence they cited the production of ''excess'' amounts of heat in an electrochemical apparatus and observation of neutron production. While the production of heat in a chemical apparatus is not in itself unusual the observation of neutrons is certainly extraordinary. As it turned out, though, careful measurements of the neutron production in electrochemical apparatus similar to that used by Fleischmann and Pons carried out at dozens of other laboratories has shown that the neutron production fails by many orders of magnitude to support the assertion by Fleischmann and Pons that their discovery represents a new and cheap source of fusion power. In particular, independent measurements of the neutron production rate suggest that the actual rate of fusion energy production probably does not exceed 1 trillionth of a watt. This paper discusses the feasibility that cold fusion is actually being achieved. 7 refs.

  4. CT image correction for beam hardening using simulated projection data

    SciTech Connect

    Meagher, J.M. (Dept. of Mechanical Engineering, California Polytechnic State Univ., San Luis Obispo, CA (US)); Mote, C.D. Jr. (Dept. of Mechanical Engineering, Univ. of California, Berkeley, CA (US)); Skinner, H.B. (Dept. of Orthopedic Surgery, Univ. of California, San Francisco, CA. (US))

    1990-08-01

    A general beam-hardening correction technique is presented. This postreconstruction method does not require the original projection data. Simulated projections through an uncorrected reconstructed image are used to correct for beam hardening. Errors in the mean linear attenuation coefficient are decreased from 30% to 5% with virtual elimination of the visual streaking artifact. The theoretical image improvement equals that of projection linearization postreconstruction methods using the original projection data. The correction is limited to cases where the material causing the beam hardening is contained within the reconstruction space.

  5. 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 ? + Gamma1 composition to an ? (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 maintained the highest ductility when compared to the uncoated sample processed under the sample conditions. Fractography of the hot-ductility samples showed features associated with increased ductility with increased soak time for all soak temperatures. Heat treatments (without elevated temperature deformation) and subsequent room temperature deformation were conducted to investigate the "in-service" behavior of 22MnB5. The uncoated and coated specimens deformed at room temperature showed similar ultimate tensile strength and ductility values. The only notable differences in the room temperature mechanical behavior of uncoated and coated samples processed under the same conditions were a result of differences in the substrate microstructure. All samples appeared to have ductile fracture features; features characteristic of liquid metal embrittlement were not observed.

  6. HYPOTHERMIA Surviving the Cold

    E-print Network

    Machel, Hans

    HYPOTHERMIA Surviving the Cold www.WorkSafebc.com #12;About the WCB Preventing on-the-job injury-HELP) toll-free in British Columbia. #12;1 Introduction Working in a cold environment ­ whether it be cold weather, cold water, or an indoor freezer ­ is part of the job for many British Columbia workers. One

  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. Point defect concentrations and hardening in binary B2 intermetallics

    SciTech Connect

    Pike, L.M.; Chang, Y.A. [Univ. of Wisconsin, Madison, WI (United States). Dept. of Materials Science and Engineering] [Univ. of Wisconsin, Madison, WI (United States). Dept. of Materials Science and Engineering; Liu, C.T. [Oak Ridge National Lab., TN (United States). Metals and Ceramics Div.] [Oak Ridge National Lab., TN (United States). Metals and Ceramics Div.

    1997-09-01

    Point defect hardening in binary B2 intermetallic compounds with the anti-structure defect structure (FeCo and AuZn) and the triple defect structure (NiAl, FeAl, and CoAl) was investigated. Thermodynamic modeling combined with experimental measurements of lattice parameters and bulk densities were used to establish point defect concentrations as functions of composition and temperature. Microhardness measurements were made on samples of varying compositions and quenching temperatures. Solution hardening rates of vacancies were found to be significantly larger than those of anti-site defects. It was possible to relate the hardening rates of anti-site defects to the magnitude of the lattice dilation. This suggests that the elastic size effect was the primary hardening mechanism. No such correlation was found for vacancies.

  9. Stimulation of Phospholipid Biosynthesis during Frost Hardening of Winter Wheat.

    PubMed

    Willemot, C

    1975-02-01

    Lipids were labeled with (33)P during frost hardening of two varieties of winter wheat (Triticum aestivum), hardy Kharkov and much less hardy Champlein. The main labeled compounds were phosphatidylcholine, phosphatidylethanolamine, phosphatidylinositol, and phosphatidylglycerol. With time of incorporation the proportion of the radioactivity incorporated into the lipids increased in phosphatidylcholine, especially in Kharkov and at 1 C. During hardening, phospholipid synthesis was greatly stimulated in Kharkov, but much less in Champlein. The proportion of the phospholipids synthesized changed only little with hardening, with a trend towards an increase in phosphatidylcholine. Increased phospholipid synthesis does not seem to be a prerequisite to hardening in winter wheat. However, a high rate of phospholipid synthesis may be required to maintain frost resistance. PMID:16659082

  10. Thermo-mechanically coupled FE analysis and sensitivity study of simultaneous hot\\/cold forging process with local inductive heating and cooling

    Microsoft Academic Search

    Anton Matzenmiller; Christoph Bröcker

    The numerical investigation of the production of a stub shaft is presented, where the highly innovative metal forming technology\\u000a of the simultaneous hot and cold forging is applied in combination with a hardening process performed directly in the closed\\u000a forging dies after the forging step similar to press hardening of sheet metal. This complex forging process is completely\\u000a analysed by

  11. Oxygen Diffusion Hardening of Ti-Nb-Zr Alloys

    Microsoft Academic Search

    R. A. Poggie; P. Kovacs; J. A. Davidson

    1996-01-01

    Ti-13Nb-13Zr (Ti-13-13) is a new titanium alloy developed for medical implant applications. In the oxygen diffusion hardened condition, Ti-13-13 and titanium alloys which possess zirconium, are hardenable at temperatures of 400 to 600°C with the end result being a passive, mechanically stable, abrasion resistant oxide ceramic surface layer of about 0.2 to 2 ?m in thickness. The thickness of this

  12. Strain hardening of fcc metal surfaces induced by microploughing

    SciTech Connect

    Day, R.D.; Dickerson, R.M. [Los Alamos National Lab., NM (United States); Russell, P.E. [North Carolina State Univ., Raleigh, NC (United States)

    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.

  13. Hydrogen embrittlement susceptibility of laser-hardened 4140 steel

    Microsoft Academic Search

    L. W Tsay; Z. W Lin; R. K Shiue; C Chen

    2000-01-01

    Slow strain rate tensile (SSRT) tests were performed to investigate the susceptibility to hydrogen embrittlement of laser-hardened AISI 4140 specimens in air, gaseous hydrogen and saturated H2S solution. Experimental results indicated that round bar specimens with two parallel hardened bands on opposite sides along the loading axis (i.e. the PH specimens), exhibited a huge reduction in tensile ductility for all

  14. Calorimetric Study of Frost Attack During Cement Hardening

    Microsoft Academic Search

    A. Usherov-Marshak; O. Zlatkovski; V. Sopov

    2002-01-01

    This report deals with practical and experimental studies of the effects of frost attack on hardening cement stone and concrete.\\u000a The basic component of concrete, cement stone, is a typical capillary-porous material formed from solid, liquid and gaseous\\u000a phases. The level of knowledge on the effects of frost attack on cement stone and concrete hardening is insufficient, due\\u000a to the

  15. Cylindrical shell buckling through strain hardening

    SciTech Connect

    Bandyopadhyay, K.; Xu, J.; Shteyngart, S. [Brookhaven National Lab., Upton, NY (United States); Gupta, D. [USDOE, Germantown, MD (United States)

    1995-04-01

    Recently, the authors published results of plastic buckling analysis of cylindrical shells. Ideal elastic-plastic material behavior was used for the analysis. Subsequently, the buckling analysis program was continued with the realistic stress-strain relationship of a stainless steel alloy which does not exhibit a clear yield point. The plastic buckling analysis was carried out through the initial stages of strain hardening for various internal pressure values. The computer program BOSOR5 was used for this purpose. Results were compared with those obtained from the idealized elastic-plastic relationship using the offset stress level at 0.2% strain as the yield stress. For moderate hoop stress values, the realistic stress-grain case shows a slight reduction of the buckling strength. But, a substantial gain in the buckling strength is observed as the hoop stress approaches the yield strength. Most importantly, the shell retains a residual strength to carry a small amount of axial compressive load even when the hoop stress has exceeded the offset yield strength.

  16. Atmospheres for the hardening of steel

    SciTech Connect

    Walton, H. [Torrington Co., Rutherfordton, NC (United States)

    1995-03-01

    Since time immemorial, atmospheres in one form or another have been used to protect steel surfaces against degradation or to impart properties that would otherwise be unobtainable. For a heat-treatment operation that includes both clean-hardening and carburizing, the most viable atmosphere option is a combination of both cryogenic nitrogen for safety purges, and on-site generation of nitrogen--membrane or PSA--and methanol. Given that a steel part is being heated to austenitizing temperature, what is the purpose of the furnace atmosphere: to protect the steel surface from oxidation, oxide scale impedes quenching speed and contaminates the quenching media and tank; to protect the steel surface from unintentional changes in the surface chemistry caused by carburization/decarburization; to intentionally change the surface chemistry of the part by adding or removing carbon and/or nitrogen; to provide a vehicle for heat transfer or loss, if a circulating fan on a batch furnace breaks down, the importance of heat transfer becomes painfully obvious. Note that for quenching high carbon steels, no atmosphere is often better than a poor atmosphere. A minimal layer of ductile ferrite caused by total decarburization under a layer of thin scale, is less prone to quench-cracking than a less ductile and often deeper layer of partial decarburization with no scale.

  17. 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 Arrays (FPAA)s for use in reconfigurable architectures. As these component/chip level technologies mature, the RHESE project emphasis shifts to focus on efforts encompassing total processor hardening techniques and board-level electronic reconfiguration techniques featuring spare and interface modularity. This phased approach to distributing emphasis between technology developments provides hardened FPGA/FPAAs for early mission infusion, then migrates to hardened, board-level, high speed processors with associated memory elements and high density storage for the longer duration missions encountered for Lunar Outpost and Mars Exploration occurring later in the Constellation schedule.

  18. 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 Uniaxial Compression of Vertically Aligned Carbon Nanotubes," J. Mech.Phys. Solids, 59, pp. 2227--2237, Erratum 60, 1753-1756 (2012)], the property space exploration was advanced to three types of simple mechanical tests: 1) uniaxial compression, 2) uniaxial tension, and 3) nanoindentation with a conical and a flat-punch tip. The simulations attempt to explain some of the salient features in experimental data, like 1) The initial linear elastic response. 2) One or more nonlinear instabilities, yielding, and hardening. The model-inherent relationships between the material properties and the overall stress-strain behavior were validated against the available experimental data. The material properties include the gradient in stiffness along the height, plastic and elastic compressibility, and hardening. Each of these tests was evaluated in terms of their efficiency in extracting material properties. The uniaxial simulation results proved to be a combination of structural and material influences. Out of all deformation paths, flat-punch indentation proved to be superior since it is the most sensitive in capturing the material properties.

  19. Nanoscale Strain-Hardening of Keratin Fibres

    PubMed Central

    Fortier, Patrick; Suei, Sandy; Kreplak, Laurent

    2012-01-01

    Mammalian appendages such as hair, quill and wool have a unique structure composed of a cuticle, a cortex and a medulla. The cortex, responsible for the mechanical properties of the fibers, is an assemblage of spindle-shaped keratinized cells bound together by a lipid/protein sandwich called the cell membrane complex. Each cell is itself an assembly of macrofibrils around 300 nm in diameter that are paracrystalline arrays of keratin intermediate filaments embedded in a sulfur-rich protein matrix. Each macrofibril is also attached to its neighbors by a cell membrane complex. In this study, we combined atomic force microscopy based nano-indentation with peak-force imaging to study the nanomechanical properties of macrofibrils perpendicular to their axis. For indentation depths in the 200 to 500 nm range we observed a decrease of the dynamic elastic modulus at 1 Hz with increasing depth. This yielded an estimate of 1.6GPa for the lateral modulus at 1 Hz of porcupine quill’s macrofibrils. Using the same data we also estimated the dynamic elastic modulus at 1 Hz of the cell membrane complex surrounding each macrofibril, i.e., 13GPa. A similar estimate was obtained independently through elastic maps of the macrofibrils surface obtained in peak-force mode at 1 kHz. Furthermore, the macrofibrillar texture of the cortical cells was clearly identified on the elasticity maps, with the boundaries between macrofibrils being 40–50% stiffer than the macrofibrils themselves. Elasticity maps after indentation also revealed a local increase in dynamic elastic modulus over time indicative of a relaxation induced strain hardening that could be explained in term of a ?-helix to ?-sheet transition within the macrofibrils. PMID:22848616

  20. THE EFFECTS OF CARBON ON THE HARDNESS, MICROSTRUCTURE, AND COLD WORKING PROPERTIES OF HIGH-PURITY NIOBIUM

    Microsoft Academic Search

    F. R. Cortes; A. L. Jr. Feild

    1962-01-01

    An investigation was conducted to determine the effects carbon on the ; hardness, microstructure, and cold workg properties of high purity niobium. ; Carbon additions of electron beam melted niobium. Results showed that carbon is ; not an effective hardener of niobium up to the maximum level studied and that it ; is present primarily as a NbâC precipitate as

  1. Hot Topics in Cold Gases

    E-print Network

    Robert Seiringer

    2009-08-25

    Since the first experimental realization of Bose-Einstein condensation in cold atomic gases in 1995 there has been a surge of activity in this field. Ingenious experiments have allowed us to probe matter close to zero temperature and reveal some of the fascinating effects quantum mechanics has bestowed on nature. It is a challenge for mathematical physicists to understand these various phenomena from first principles, that is, starting from the underlying many-body Schr\\"odinger equation. Recent progress in this direction concerns mainly equilibrium properties of dilute, cold quantum gases. We shall explain some of the results in this article, and describe the mathematics involved in understanding these phenomena. Topics include the ground state energy and the free energy at positive temperature, the effect of interparticle interaction on the critical temperature for Bose-Einstein condensation, as well as the occurrence of superfluidity and quantized vortices in rapidly rotating gases.

  2. Cold Stress and the Cold Pressor Test

    ERIC Educational Resources Information Center

    Silverthorn, Dee U.; Michael, Joel

    2013-01-01

    Temperature and other environmental stressors are known to affect blood pressure and heart rate. In this activity, students perform the cold pressor test, demonstrating increased blood pressure during a 1- to 2-min immersion of one hand in ice water. The cold pressor test is used clinically to evaluate autonomic and left ventricular function. This…

  3. Post Treatment Laser Irradiation For Recovery Of Deformation Induced By Surface Laser Hardening

    NASA Astrophysics Data System (ADS)

    Casalino, Giuseppe; Giorleo, Luca; Capello, Edoardo

    2009-11-01

    In order to improve the wear resistance of parts without affecting the softer, tough interior of the part, laser hardening offers many advantages. Compared to conventional processes, only a shallow layer of the metal part is heated by laser irradiation to just below the melting temperature, while the surrounding material remains at ambient temperature. Due to heat conduction into the bulk material, the surface will cool down as soon as the laser beam moves away. This self-quenching creates a particularly fine-grained martensitic micro structure with high hardness without causing fragileness of the base material. Notably lower distortions of parts avoiding costly rework are produced due to laser beam follows the contours precisely. Nevertheless, when part is thin and slim even the low distortion caused by the laser hardening can deeply affects the part ability to function fairly. In this paper a double treatment is proposed in order to recover the bending and bulging deformation induced by the thermal cycle and phase transformation. Both the numerical and experimental approaches were used in a synergic attempt to rapidly achieve the goal of minimizing the displacements to a steel laser-hardened edge of a thin blade for fibers cutting application. The modeling parameters comprise geometries, laser characters, material properties and mechanical properties; the model was built by means of the finite element method. In order to validate the numerical model the experimental and numerical outputs were crosschecked. The numerical model built up for this demonstration is able to extend its predicting ability to a vast range of similar applications.

  4. Cold and Cough Medicines

    MedlinePLUS

    ... What can you do for your cold or cough symptoms? Besides drinking plenty of fluids and getting ... medicines. There are lots of different cold and cough medicines, and they do different things. Nasal decongestants - ...

  5. Hardening treatment of machine parts with CO2 power lasers

    NASA Astrophysics Data System (ADS)

    Borodachev, A. S.; Gutman, M. B.; Kuznetsov, G. A.; Medvedovskaya, L. A.; Rubin, G. K.

    1986-01-01

    Two technological laser facilities were built at the All-Union Scientific Research Institute of Electrothermal Equipment for hardening machine parts using 1.2 and 2.5 kW CO2 lasers. Both lasers are continuous wave devices with self sustained gas discharge between flat anode and tubular cathode. Each facility includes a Fabry-Perot resonator, a beam transporting and focusing mechanism, a laser power measuring instrument with a movable beam chopping mirror, and a helium/neon simulating laser with two mirrors for precision alignment of parts. These facilities are intended not only for hardening, but also for annealing, plating, and alloying. Under consideration is also use for welding and cutting. Materials hardenable with these facilities range from perlite iron to chromium steels. Experimentally hardened parts include tool bits, gear teeth, zinc extrusion plungers, bearing races, king pins, bolts, and even diesel cylinders. Hardening is done to ensure high wear resistance of the materials and long service life for the part.

  6. Computer modelling of age hardening for cast aluminium alloys

    NASA Astrophysics Data System (ADS)

    Wu, Linda; Ferguson, W. George

    2009-08-01

    Age hardening, or precipitation hardening, is one of the most widely adopted techniques for strengthening of aluminium alloys. Although various age hardening models have been developed for aluminium alloys, from the large volume of literature reviewed, it appears that the bulk of the research has been concentrated on wrought aluminium alloys, only a few of the established precipitation models have been applied to the casting aluminium alloys. In the present work, there are two modelling methods that have been developed and applied to the casting aluminium alloys A356 and A357. One is based on the Shercliff-Ashby methodology to produce a process model, by which we mean a mathematical relationship between process variables (alloy composition, ageing temperature and time) and material properties (yield strength or hardness) through microstructure evolution (precipitate radius, volume fraction). The other method is based on the Kampmann and Wagner Numerical (KWN) model which deals with concomitant nucleation, growth and coarsening and is thus capable of predicting the full evolution of the particle size distribution and then a strength model is used to evaluate the resulting change in hardness or yield strength at room temperature by taking into account contributions from lattice resistance, solid solution hardening and precipitation hardening.

  7. Cryptographic Path Hardening: Hiding Vulnerabilities in Software through Cryptography

    E-print Network

    Ganesh, Vijay; Rinard, Martin

    2012-01-01

    We propose a novel approach to improving software security called Cryptographic Path Hardening, which is aimed at hiding security vulnerabilities in software from attackers through the use of provably secure and obfuscated cryptographic devices to harden paths in programs. By "harden" we mean that certain error-checking if-conditionals in a given program P are replaced by equivalent" we mean that adversaries cannot use semi-automatic program analysis techniques to reason about the hardened program paths and thus cannot discover as-yet-unknown errors along those paths, except perhaps through black-box dictionary attacks or random testing (which we can never prevent). Other than these unpreventable attack methods, we can make program analysis aimed at error-finding "provably hard" for a resource-bounded attacker, in the same sense that cryptographic schemes are hard to break. Unlike security-through-obscurity, in Cryptographic Path Hardening we use provably-secure crypto devices to hide errors and our mathemati...

  8. Quantum optics of ultra-cold molecules

    Microsoft Academic Search

    D. Meiser; T. Miyakawa; H. Uys; P. Meystre

    2005-01-01

    Quantum optics has been a major driving force behind the rapid experimental developments that have led from the first laser cooling schemes to the Bose-Einstein condensation (BEC) of dilute atomic and molecular gases. Not only has it provided experimentalists with the necessary tools to create ultra-cold atomic systems, but it has also provided theorists with a formalism and framework to

  9. Titanium Cold Spray Coatings

    Microsoft Academic Search

    Jihane Ajaja; Dina Goldbaum; Richard Chromik; Stephen Yue; Ahmad Rezaeian; Wilson Wong; Eric Irissou; Jean-Gabriel Legoux

    2010-01-01

    Titanium Cold Spray Coatings Cold Spray is an emerging technology used for the deposition of coatings for many industries including aerospace. This technique allows the deposition of metallic materials at low temper-atures below their melting point. The aim of this research was to develop a test technique that can measure the degree to which a cold spray coating achieves mechanical

  10. 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.

  11. Transient radiation hardened CMOS (Complementary Metal Oxide Semiconductor) operational amplifiers

    NASA Astrophysics Data System (ADS)

    Trombley, Gerald J.

    General strategies are developed for designing radiation hardened bulk and silicon on insulator (SOI) complementary metal oxide semiconductor (CMOS) operational amplifiers. Comparisons are made between each technology concerning photocurrent mechanisms and the inherent advantages of SOI CMOS. Methods are presented for analyzing circuit designs and minimizing the net photocurrent responses. Analysis is performed on standard operational amplifier circuits and subcircuits to demonstrate the usefulness of these methods. Radiation hardening topics discussed include superior radiation hardened topologies, photocurrent compensation and its limitations, and methods to ensure a preferred direction of photocurrent response. Several operational amplifier subcircuits are compared for their hardness characteristics. Folded cascade and three-stage operational amplifiers were fabricated on an SOI CMOS test chip supported by Texas Instruments, Incorporated. At the time of publication, the circuit operation was verified but radiation data were not yet available.

  12. Determination of Anisotropic Hardening of Sheet Metals by Shear Tests

    NASA Astrophysics Data System (ADS)

    Schikorra, Marco; Brosius, Alexander; Kleiner, Matthias

    2005-08-01

    With regard to the increasing necessity of accurate material data determination for the prediction of springback, a material testing equipment has been developed and set up for the measurement of material hardening within cyclic loading. One reason for inaccurate springback predictions can be seen in a missing consideration of load reversal effects in a realistic material model description. Due to bending and unbending while the material is drawn from the flange over a radius of a deep drawing tool, a hardening takes place which leads to an expanding or shifting of the elastic area and yield locus known as isotropic, kinematic, or combined hardening. Since springback is mainly influenced by the actual stress state and a correct distinction between elastic and elastic-plastic regions, an accurate prediction of these stress and strain components is basically required to simulate springback accurately, too. The presented testing method deals with shearing of sheet metal specimens in one or more load cycles to analyze the change of yield point and yield curve. The experimental set up is presented and discussed and the results are shown for different materials such as aluminum A199.5, stainless steel X5CrNi18.10, dual phase steel DP600, and copper Cu99.99. To guarantee a wide experimental range, different sheet thicknesses were used additionally. Simulations using the finite element method were carried out to compare the measured results with calculated results from different yield criterions and different hardening laws mentioned above. It was possible to show that commonly used standard material hardening laws like isotropic and kinematic hardening laws often do not lead to accurate stress state predictions when load reversals occur. The work shows the range of occurring differences and strategies to obtain to a more reliable prediction.

  13. Electrically induced temperature difference and deformation in hardened cement pastes

    SciTech Connect

    Sun Mingqing [Department of Engineering Structures and Mechanics, Wuhan University of Technology, Wuhan 430070 (China)]. E-mail: sunmingqing@yahoo.com; Wang Xiaoying [Department of Engineering Structures and Mechanics, Wuhan University of Technology, Wuhan 430070 (China); Zhao Kairui [Department of Engineering Structures and Mechanics, Wuhan University of Technology, Wuhan 430070 (China); Li Zhuoqiu [Department of Engineering Structures and Mechanics, Wuhan University of Technology, Wuhan 430070 (China)

    2006-12-15

    Electromechanical effect of hardened cement paste beam is investigated in this paper. When an external electrical current is applied to the electrodes attached to opposite surfaces of a cement beam, it is found that temperature on the positive electrode is always higher than that on the negative electrode. The sign of electrically induced temperature difference is determined by the direction of applied electrical current. Electrically induced temperature difference makes the beam bend towards the surface with a higher temperature. Both electrically induced temperature difference and electroosmosis lead to electromechanical effect of hardened cement paste. Finally, electromechanical effect becomes more obvious by adding NaCl to cement paste.

  14. 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.

  15. Cold Nuclear Matter Effects on J/psi Yields as a Function of Rapidity and Nuclear Geometry in Deuteron-Gold Collisions at sqrt(s_NN) = 200 GeV

    E-print Network

    A. Adare; S. Afanasiev; C. Aidala; N. N. Ajitanand; Y. Akiba; H. Al-Bataineh; J. Alexander; A. Angerami; K. Aoki; N. Apadula; L. Aphecetche; Y. Aramaki; J. Asai; E. T. Atomssa; R. Averbeck; T. C. Awes; B. Azmoun; V. Babintsev; M. Bai; G. Baksay; L. Baksay; A. Baldisseri; K. N. Barish; P. D. Barnes; B. Bassalleck; A. T. Basye; S. Bathe; S. Batsouli; V. Baublis; C. Baumann; A. Bazilevsky; S. Belikov; R. Belmont; R. Bennett; A. Berdnikov; Y. Berdnikov; J. H. Bhom; A. A. Bickley; D. S. Blau; J. G. Boissevain; J. S. Bok; H. Borel; K. Boyle; M. L. Brooks; H. Buesching; V. Bumazhnov; G. Bunce; S. Butsyk; C. M. Camacho; S. Campbell; A. Caringi; B. S. Chang; W. C. Chang; J. -L. Charvet; C. -H. Chen; S. Chernichenko; C. Y. Chi; M. Chiu; I. J. Choi; J. B. Choi; R. K. Choudhury; P. Christiansen; T. Chujo; P. Chung; A. Churyn; O. Chvala; V. Cianciolo; Z. Citron; B. A. Cole; Z. Conesa del Valle; M. Connors; P. Constantin; M. Csanád; T. Csörg\\Ho; T. Dahms; S. Dairaku; I. Danchev; K. Das; A. Datta; G. David; M. K. Dayananda; A. Denisov; D. d'Enterria; A. Deshpande; E. J. Desmond; K. V. Dharmawardane; O. Dietzsch; A. Dion; M. Donadelli; L. D Orazio; O. Drapier; A. Drees; K. A. Drees; A. K. Dubey; J. M. Durham; A. Durum; D. Dutta; V. Dzhordzhadze; S. Edwards; Y. V. Efremenko; F. Ellinghaus; T. Engelmore; A. Enokizono; H. En'yo; S. Esumi; K. O. Eyser; B. Fadem; D. E. Fields; M. Finger; \\, Jr.; M. Finger; F. Fleuret; S. L. Fokin; Z. Fraenkel; J. E. Frantz; A. Franz; A. D. Frawley; K. Fujiwara; Y. Fukao; T. Fusayasu; I. Garishvili; A. Glenn; H. Gong; M. Gonin; J. Gosset; Y. Goto; R. Granier de Cassagnac; N. Grau; S. V. Greene; G. Grim; M. Grosse Perdekamp; T. Gunji; H. -Å. Gustafsson; A. Hadj Henni; J. S. Haggerty; K. I. Hahn; H. Hamagaki; J. Hamblen; J. Hanks; R. Han; E. P. Hartouni; K. Haruna; E. Haslum; R. Hayano; M. Heffner; T. K. Hemmick; T. Hester; X. He; J. C. Hill; M. Hohlmann; W. Holzmann; K. Homma; B. Hong; T. Horaguchi; D. Hornback; S. Huang; T. Ichihara; R. Ichimiya; H. Iinuma; Y. Ikeda; K. Imai; J. Imrek; M. Inaba; D. Isenhower; M. Ishihara; T. Isobe; M. Issah; A. Isupov; D. Ivanischev; Y. Iwanaga; B. V. Jacak J. Jia; X. Jiang; J. Jin; B. M. Johnson; T. Jones; K. S. Joo; D. Jouan; D. S. Jumper; F. Kajihara; S. Kametani; N. Kamihara; J. Kamin; J. H. Kang; J. Kapustinsky; K. Karatsu; M. Kasai; D. Kawall; M. Kawashima; A. V. Kazantsev; T. Kempel; A. Khanzadeev; K. M. Kijima; J. Kikuchi; A. Kim; B. I. Kim; D. H. Kim; D. J. Kim; E. J. Kim; E. Kim; S. H. Kim; Y. -J. Kim; E. Kinney; K. Kiriluk; Á. Kiss; E. Kistenev; J. Klay; C. Klein-Boesing; L. Kochenda; B. Komkov; M. Konno; J. Koster; A. Kozlov; A. Král; A. Kravitz; G. J. Kunde; K. Kurita; M. Kurosawa; M. J. Kweon; Y. Kwon; G. S. Kyle; R. Lacey; Y. S. Lai; J. G. Lajoie; D. Layton; A. Lebedev; D. M. Lee; J. Lee; K. B. Lee; K. S. Lee; T. Lee; M. J. Leitch; M. A. L. Leite; B. Lenzi; P. Lichtenwalner; P. Liebing; L. A. Linden Levy; T. Liška; A. Litvinenko; H. Liu; M. X. Liu; X. Li; B. Love; D. Lynch; C. F. Maguire; Y. I. Makdisi; A. Malakhov; M. D. Malik; V. I. Manko; E. Mannel; Y. Mao; L. Mašek; H. Masui; F. Matathias; M. McCumber; P. L. McGaughey; D. McGlinchey; N. Means; B. Meredith; Y. Miake; T. Mibe; A. C. Mignerey; P. Mikeš; K. Miki; A. Milov; M. Mishra; J. T. Mitchell; A. K. Mohanty; H. J. Moon; Y. Morino; A. Morreale; D. P. Morrison; T. V. Moukhanova; D. Mukhopadhyay; T. Murakami; J. Murata; S. Nagamiya; J. L. Nagle; M. Naglis; M. I. Nagy; I. Nakagawa; Y. Nakamiya; K. R. Nakamura; T. Nakamura; K. Nakano; S. Nam; J. Newby; M. Nguyen; M. Nihashi; T. Niita; R. Nouicer; A. S. Nyanin; C. Oakley; E. O'Brien; S. X. Oda; C. A. Ogilvie; K. Okada; M. Oka; Y. Onuki; A. Oskarsson; M. Ouchida; K. Ozawa; R. Pak; A. P. T. Palounek; V. Pantuev; V. Papavassiliou; I. H. Park; J. Park; S. K. Park; W. J. Park; S. F. Pate; H. Pei; J. -C. Peng; H. Pereira; V. Peresedov; D. Yu. Peressounko; R. Petti; C. Pinkenburg; R. P. Pisani; M. Proissl; M. L. Purschke; A. K. Purwar; H. Qu; J. Rak; A. Rakotozafindrabe; I. Ravinovich; K. F. Read; S. Rembeczki; K. Reygers; V. Riabov; Y. Riabov; E. Richardson; D. Roach; G. Roche; S. D. Rolnick; M. Rosati; C. A. Rosen; S. S. E. Rosendahl; P. Rosnet; P. Rukoyatkin; P. Ruži?ka; V. L. Rykov; B. Sahlmueller; N. Saito; T. Sakaguchi; S. Sakai; K. Sakashita; V. Samsonov; S. Sano; T. Sato; S. Sawada; K. Sedgwick; J. Seele; R. Seidl; A. Yu. Semenov; V. Semenov; R. Seto; D. Sharma; I. Shein; T. -A. Shibata; K. Shigaki; M. Shimomura; K. Shoji; P. Shukla; A. Sickles; C. L. Silva; D. Silvermyr; C. Silvestre; K. S. Sim; B. K. Singh; C. P. Singh; V. Singh; M. Slune?ka; A. Soldatov; R. A. Soltz; W. E. Sondheim; S. P. Sorensen; I. V. Sourikova; F. Staley; P. W. Stankus; E. Stenlund; M. Stepanov; A. Ster; S. P. Stoll; T. Sugitate; C. Suire; A. Sukhanov; J. Sziklai; E. M. Takagui; A. Taketani; R. Tanabe; Y. Tanaka; S. Taneja; K. Tanida

    2010-10-06

    We present measurements of J/psi yields in d+Au collisions at sqrt(s_NN) = 200 GeV recorded by the PHENIX experiment and compare with yields in p+p collisions at the same energy per nucleon-nucleon collision. The measurements cover a large kinematic range in J/psi rapidity (-2.2 < y < 2.4) with high statistical precision and are compared with two theoretical models: one with nuclear shadowing combined with final state breakup and one with coherent gluon saturation effects. To remove model dependent systematic uncertainties we also compare the data to a simple geometric model. We find that calculations where the nuclear modification is linear or exponential in the density weighted longitudinal thickness are difficult to reconcile with the forward rapidity data.

  16. Cold Nuclear Matter Effects on J/{psi} Yields as a Function of Rapidity and Nuclear Geometry in d+A Collisions at {radical}(s{sub NN})=200 GeV

    SciTech Connect

    Adare, A.; Bickley, A. A.; Ellinghaus, F.; Kinney, E.; Kiriluk, K.; Linden Levy, L. A.; Nagle, J. L.; Rosen, C. A.; Seele, J.; Wysocki, M. [University of Colorado, Boulder, Colorado 80309 (United States); Afanasiev, S.; Isupov, A.; Litvinenko, A.; Malakhov, A.; Peresedov, V.; Rukoyatkin, P.; Zolin, L. [Joint Institute for Nuclear Research, 141980 Dubna, Moscow Region (Russian Federation); Aidala, C.; Datta, A. [Department of Physics, University of Massachusetts, Amherst, Massachusetts 01003-9337 (United States); Ajitanand, N. N. [Chemistry Department, Stony Brook University, SUNY, Stony Brook, New York 11794-3400 (United States)

    2011-09-30

    We present measurements of J/{psi} yields in d+Au collisions at {radical}(s{sub NN})=200 GeV recorded by the PHENIX experiment and compare them with yields in p+p collisions at the same energy per nucleon-nucleon collision. The measurements cover a large kinematic range in J/{psi} rapidity (-2.2rapidity data are inconsistent with nuclear modifications that are linear or exponential in the density weighted longitudinal thickness, such as those from the final state breakup of the bound state.

  17. 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 apparent hardness was found. Aging also lead to an unexpected and concurrent increase in ductility and impact toughness. The alloys also showed an increase in strain hardening on aging. The increase in ductility varied with the v/o martensite in the microstructure and was shown to occur after short time intervals at the optimum aging temperature. Compressive strength measurements revealed that the increase in ductility was due to the relaxation of residuals stresses that occur when the high temperature austenite transforms to martensite in the dual phase microstructure. The specific volume of martensite is much larger than that of austenite so that when the transformation takes place, a compressive stress is induced in the ferrite. In the sintered state, the residual stress leads to a higher work hardening rate in tension. When the alloy is aged, the work hardening rate is reduced and the ductility is increased compared with the sintered state, even though aging increases the strength and apparent hardness.

  18. Effect of the hardened layer thickness of the formation of mesostructures during extension of surface hardened samples

    NASA Astrophysics Data System (ADS)

    Panin, V. E.; Slosman, A. I.; Kolesova, N. A.; Molchunova, I. Yu.; Ovechkin, B. B.

    1998-06-01

    We have made a systematic experimental study of the effect of the thickness of the surface hardened layer in planar samples of 65X13 steel on the geometric parameters of the quasiperiodic mesobustructures which are formed in the surface layer and the bulk of the sample during its plastic extension. The observed dependence of the dimensions of the fragments of mesosubstructure on the thickness of the surface hardened layer correlates well with theoretical calculations [1, 2] of the mechanical or thermal stress at the interface of two media in an external field.

  19. Open photoacoustic cell for thermal diffusivity measurements of a fast hardening cement used in dental restoring

    NASA Astrophysics Data System (ADS)

    Astrath, F. B. G.; Astrath, N. G. C.; Baesso, M. L.; Bento, A. C.; Moraes, J. C. S.; Santos, A. D.

    2012-01-01

    Thermal diffusivity and conductivity of dental cements have been studied using open photoacoustic cell (OPC). The samples consisted of fast hardening cement named CER, developed to be a root-end filling material. Thermal characterization was performed in samples with different gel/powder ratio and particle sizes and the results were compared to the ones from commercial cements. Complementary measurements of specific heat and mass density were also performed. The results showed that the thermal diffusivity of CER tends to increase smoothly with gel volume and rapidly against particle size. This behavior was linked to the pores size and their distribution in the samples. The OPC method was shown to be a valuable way in deriving thermal properties of porous material.

  20. Structural study of oriental lacquer films during the hardening process

    Microsoft Academic Search

    Noriyasu Niimura; Tetsuo Miyakoshi

    2006-01-01

    Oriental lacquer is the natural resin obtained by tapping lac trees. It hardens into a tough and insoluble film. The extreme hardness and insolubility are some of the most important functions, which are required for industrial coating materials. In this study, two kinds of oriental lacquer films, traditionally named Kiurushi (raw urushi) and Kuromeurushi produced by two different pretreatments, were

  1. Laser-acoustic method for hardening the tool steels

    Microsoft Academic Search

    A. V. Brover; A. N. Kochetov

    2007-01-01

    The hardening of the metallic materials by concentrated energy fluxes (specifically, by ultrasonic action) in their various combinations makes it possible to intensify the existing technological processes and achieve results that cannot be achieved using the traditional technology. The connection between the surface layer quality characteristics and the properties of the articles indicates that the optimal surface should have the

  2. Post-reconstruction method for beam hardening in computerised tomography

    Microsoft Academic Search

    O. Nalcioglu; R. Y. Lou

    1979-01-01

    A method for correcting the beam hardening artefacts in computerised tomography is introduced. After an initial reconstruction of the object the uncorrected image is used to estimate the amount of bone and tissue along each ray. The bone and tissue lengths obtained from the initial reconstruction are used to add a correction term to each original projection. A second reconstruction

  3. Radiation hardened high efficiency silicon space solar cell

    Microsoft Academic Search

    V. Garboushian; S. Yoon; J. Turner

    1993-01-01

    A silicon solar cell with AMO 19% Beginning of Life (BOL) efficiency is reported. The cell has demonstrated equal or better radiation resistance when compared to conventional silicon space solar cells. Conventional silicon space solar cell performance is generally ≈14% at BOL. The Radiation Hardened High Efficiency Silicon (RHHES) cell is thinned for high specific power (watts\\/kilogram). The RHHES space

  4. Simulations of dislocation glide in overaged precipitation-hardened crystals

    Microsoft Academic Search

    Volker Mohles

    2001-01-01

    Precipitation hardening of metals and alloys is investigated by means of computer simulations of dislocations gliding through a matrix with spherical coherent precipitates. The critical resolved shear stress is derived. Most realistic models are applied in these simulations: the radius distribution and the threedimensional spatial arrangement of the particles are close to those of an actual Ostwald ripened crystal. Unlike

  5. Simulations of dislocation glide in overaged precipitation-hardened crystals

    Microsoft Academic Search

    Volker Mohles

    2001-01-01

    Precipitation hardening of metals and alloys is investigated by means of computer simulations of dislocations gliding through a matrix with spherical coherent precipitates. The critical resolved shear stress is derived. Most realistic models are applied in these simulations: the radius distribution and the three-dimensional spatial arrangement of the particles are close to those of an actual Ostwald ripened crystal. Unlike

  6. The Hardening of Satellite Cables to X-Rays

    Microsoft Academic Search

    D. M. Clement; R. A. Lowell

    1978-01-01

    Various hardening techniques for shielded satellite cables exposed to X-rays are experimentally investigated. The most promising technique that maintains flight quality of the cables without increasing weight significantly is the use of an additional layer of conductive plastic around each primary wire's insulation. The principal effect of the conductive plastic is to shunt the kinetic charge emitted from the shield

  7. 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.

  8. A new technique for hardening optically-triggered thyristors

    SciTech Connect

    Carson, R.F.; Hughes, R.C.; Weaver, H.T.; Brennan, T.M.; Hammons, B.E.

    1990-01-01

    Optically-triggered thyristors are hardened to high x-ray dose rates by the addition of a monolithically integrated compensating photodetector. Tests of discrete device arrangements show radiation-induced switching is completely inhibited up to 1.4 {times} 10{sup 9} rad (Si)/sec. 1 ref., 4 figs.

  9. DEFORMATION MODES ?' PRECIPITATION HARDENED NICKEL-BASE ALLOYS

    Microsoft Academic Search

    B. H. KEAR; J. M. OBLAK

    1974-01-01

    By a detailed consideration of the geometrical consequences of shear displacements in Llz y' and the requirement of compatibility with the fcc y matrix, it has been possible to define the shear modes potentially operative in y' precipitation hardened nickel-base alloys. Most of these geometrically possible deformation modes have, in fact, been observed. The predominant mecha- nisms are planar glide

  10. Hardening Soft Information Sources William W. Cohen \\Lambda

    E-print Network

    Cohen, William W.

    Hardening Soft Information Sources William W. Cohen \\Lambda AT&T Labs--Research Shannon Laboratory structured information, but the resulting databases are ``soft'': they contain inconsistencies'' databases. Here we formally model a soft database as a noisy version of some unknown hard database. We

  11. 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

  12. Radiation Hardening in Magnox Pressure-Vessel Steels

    Microsoft Academic Search

    S. B. Fisher; J. E. Harbottle; N. Aldridge

    1985-01-01

    The ferritic steels used for reactor pressure vessels undergo a marked transition from ductile to brittle fracture behaviour over a relatively narrow temperature range. For most unirradiated mild steels the ductile to brittle transition temperature (d.b.t.t.) is between -50 degrees and 20 degrees C. The process of irradiation hardening, through the formation of clusters of intersitial or vacancy defects, increases

  13. Cost-Effective Radiation Hardening Technique for Combinational Logic

    E-print Network

    Mohanram, Kartik

    Cost-Effective Radiation Hardening Technique for Combinational Logic Quming Zhou and Kartik that have the lowest logical masking probability to achieve cost-effective tradeoffs between overhead efficient and accurate (in comparison to SPICE). A full set of experimental results demonstrate the cost-effective

  14. Comparison between shot peening and surface nanocrystallization and hardening processes

    Microsoft Academic Search

    K. Dai; L. Shaw

    2007-01-01

    The surface nanocrystallization and hardening (SNH) is a relatively new process that has been developed to enhance fatigue and wear resistances. The SNH is similar to widely used shot peening (SP) in the sense that both processes entail repeated impacts of the work-piece surface with spheres. The difference between them lies in the sizes of spheres and the impact velocities

  15. 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.

  16. Ferritic, martensitic, and precipitation hardening stainless steel laser weldings

    Microsoft Academic Search

    Giuseppe Daurelio; Antonio D. Ludovico; Christos N. Panagopoulos; Corrado Tundo

    1998-01-01

    Even if many steels and alloys have been welded on the last years, nowadays there are some other stainless steel alloys that need a further comprehension when they have to be welded. Typically these alloys are martensitic and precipitation hardening ones that still present some problems to be weld, i.e. hot cracks, fragile beads, an excessive grain size and other

  17. Experimental study of self-compacted concrete in hardened state

    Microsoft Academic Search

    Carlos Jose Parra Costa

    2006-01-01

    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

  18. Method for increasing the rate of compressive strength gain in hardenable mixtures containing fly ash

    Microsoft Academic Search

    John W. Liskowitz; Methi Wecharatana; Chai Jaturapitakkul; 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.

  19. Cyclic loading of beams based on the Prager and Frederick–Armstrong kinematic hardening models

    Microsoft Academic Search

    H. Mahbadi; M. R. Eslami

    2002-01-01

    The kinematic hardening theory of plasticity based on the Prager and Frederick–Armstrong models are used to evaluate the cyclic loading behavior of a beam under the axial, bending, and thermal loads. The beam material is assumed to follow non-linear strain hardening property. The material's strain hardening curves in tension and compression are assumed to be both identical for the isotropic

  20. Time-dependent behaviour of hardened cement paste under isotropic loading

    E-print Network

    Paris-Sud XI, Université de

    1 Time-dependent behaviour of hardened cement paste under isotropic loading Manh-Huyen Vu1,2 , Jean results of isotropic compression tests performed at 20°C and 90°C on a class G hardened cement paste of the test temperature on the viscous response of hardened cement paste showing that the creep is more

  1. Cold Nuclear Matter Effects on J\\/psi Yields as a Function of Rapidity and Nuclear Geometry in Deuteron-Gold Collisions at sqrt(s_NN) = 200 GeV

    Microsoft Academic Search

    A. Adare; S. Afanasiev; C. Aidala; N. N. Ajitanand; Y. Akiba; H. Al-Bataineh; J. Alexander; A. Angerami; K. Aoki; N. Apadula; L. Aphecetche; Y. Aramaki; J. Asai; E. T. Atomssa; R. Averbeck; T. C. Awes; B. Azmoun; V. Babintsev; M. Bai; G. Baksay; L. Baksay; A. Baldisseri; K. N. Barish; P. D. Barnes; B. Bassalleck; A. T. Basye; S. Batsouli; V. Baublis; C. Baumann; A. Bazilevsky; S. Belikov; R. Belmont; R. Bennett; A. Berdnikov; Y. Berdnikov; J. H. Bhom; A. A. Bickley; D. S. Blau; J. G. Boissevain; J. S. Bok; H. Borel; K. Boyle; M. L. Brooks; H. Buesching; V. Bumazhnov; G. Bunce; S. Butsyk; C. M. Camacho; S. Campbell; A. Caringi; B. S. Chang; W. C. Chang; J.-L. Charvet; C.-H. Chen; S. Chernichenko; C. Y. Chi; M. Chiu; I. J. Choi; J. B. Choi; R. K. Choudhury; P. Christiansen; T. Chujo; P. Chung; A. Churyn; O. Chvala; V. Cianciolo; Z. Citron; B. A. Cole; Z. Conesa del Valle; M. Connors; P. Constantin; M. Csanád; T. CsörgHo; T. Dahms; S. Dairaku; I. Danchev; K. Das; A. Datta; G. David; M. K. Dayananda; A. Denisov; D. d'Enterria; A. Deshpande; E. J. Desmond; K. V. Dharmawardane; O. Dietzsch; A. Dion; M. Donadelli; L. D Orazio; O. Drapier; A. Drees; K. A. Drees; A. K. Dubey; J. M. Durham; A. Durum; D. Dutta; V. Dzhordzhadze; S. Edwards; Y. V. Efremenko; F. Ellinghaus; T. Engelmore; A. Enokizono; H. En'yo; S. Esumi; K. O. Eyser; B. Fadem; D. E. Fields; M. Finger; F. Fleuret; S. L. Fokin; Z. Fraenkel; J. E. Frantz; A. Franz; A. D. Frawley; K. Fujiwara; Y. Fukao; T. Fusayasu; I. Garishvili; A. Glenn; H. Gong; M. Gonin; J. Gosset; Y. Goto; R. Granier de Cassagnac; N. Grau; S. V. Greene; G. Grim; M. Grosse Perdekamp; T. Gunji; H.-Å. Gustafsson; A. Hadj Henni; J. S. Haggerty; K. I. Hahn; H. Hamagaki; J. Hamblen; J. Hanks; R. Han; E. P. Hartouni; K. Haruna; E. Haslum; R. Hayano; M. Heffner; T. K. Hemmick; T. Hester; X. He; J. C. Hill; M. Hohlmann; W. Holzmann; K. Homma; B. Hong; T. Horaguchi; D. Hornback; S. Huang; T. Ichihara; R. Ichimiya; H. Iinuma; Y. Ikeda; K. Imai; J. Imrek; M. Inaba; D. Isenhower; M. Ishihara; T. Isobe; M. Issah; A. Isupov; D. Ivanischev; Y. Iwanaga; B. V. Jacak J. Jia; X. Jiang; J. Jin; B. M. Johnson; T. Jones; K. S. Joo; D. Jouan; D. S. Jumper; F. Kajihara; S. Kametani; N. Kamihara; J. Kamin; J. H. Kang; J. Kapustinsky; K. Karatsu; M. Kasai; D. Kawall; M. Kawashima; A. V. Kazantsev; T. Kempel; A. Khanzadeev; K. M. Kijima; J. Kikuchi; A. Kim; B. I. Kim; D. H. Kim; D. J. Kim; E. J. Kim; S. H. Kim; Y.-J. Kim; E. Kinney; K. Kiriluk; Á. Kiss; E. Kistenev; J. Klay; C. Klein-Boesing; L. Kochenda; B. Komkov; M. Konno; J. Koster; A. Kozlov; A. Král; A. Kravitz; G. J. Kunde; K. Kurita; M. Kurosawa; M. J. Kweon; Y. Kwon; G. S. Kyle; R. Lacey; Y. S. Lai; J. G. Lajoie; D. Layton; A. Lebedev; D. M. Lee; J. Lee; K. B. Lee; K. S. Lee; T. Lee; M. J. Leitch; M. A. L. Leite; B. Lenzi; P. Lichtenwalner; P. Liebing; L. A. Linden Levy; T. Liška; A. Litvinenko; H. Liu; M. X. Liu; X. Li; B. Love; D. Lynch; C. F. Maguire; Y. I. Makdisi; A. Malakhov; M. D. Malik; V. I. Manko; E. Mannel; Y. Mao; L. Mašek; H. Masui; F. Matathias; M. McCumber; P. L. McGaughey; D. McGlinchey; N. Means; B. Meredith; Y. Miake; T. Mibe; A. C. Mignerey; P. Mikeš; K. Miki; A. Milov; M. Mishra; J. T. Mitchell; A. K. Mohanty; H. J. Moon; Y. Morino; A. Morreale; T. V. Moukhanova; D. Mukhopadhyay; T. Murakami; J. Murata; S. Nagamiya; J. L. Nagle; M. Naglis; M. I. Nagy; I. Nakagawa; Y. Nakamiya; K. R. Nakamura; T. Nakamura; K. Nakano; S. Nam; J. Newby; M. Nguyen; M. Nihashi; T. Niita; R. Nouicer; A. S. Nyanin; C. Oakley; E. O'Brien; S. X. Oda; C. A. Ogilvie; K. Okada; M. Oka; Y. Onuki; A. Oskarsson; M. Ouchida; K. Ozawa; R. Pak; A. P. T. Palounek; V. Pantuev; V. Papavassiliou; I. H. Park; S. K. Park; W. J. Park; S. F. Pate; H. Pei; J.-C. Peng; H. Pereira; V. Peresedov; D. Yu. Peressounko; R. Petti; C. Pinkenburg; R. P. Pisani; M. Proissl; M. L. Purschke; A. K. Purwar; H. Qu; J. Rak; A. Rakotozafindrabe; I. Ravinovich; K. F. Read; S. Rembeczki; K. Reygers; V. Riabov; Y. Riabov; E. Richardson; D. Roach; G. Roche; S. D. Rolnick; M. Rosati; C. A. Rosen; S. S. E. Rosendahl; P. Rosnet; P. Rukoyatkin; P. Ruži?ka; V. L. Rykov; B. Sahlmueller; N. Saito; T. Sakaguchi; S. Sakai; K. Sakashita; V. Samsonov; S. Sano; T. Sato; S. Sawada; K. Sedgwick; J. Seele; R. Seidl; A. Yu. Semenov; V. Semenov; R. Seto; D. Sharma; I. Shein; T.-A. Shibata; K. Shigaki; M. Shimomura; K. Shoji; P. Shukla; A. Sickles; C. L. Silva; D. Silvermyr; C. Silvestre; K. S. Sim; B. K. Singh; C. P. Singh; V. Singh; M. Slune?ka; A. Soldatov; R. A. Soltz; W. E. Sondheim; S. P. Sorensen; I. V. Sourikova; F. Staley; P. W. Stankus; E. Stenlund; M. Stepanov; A. Ster; S. P. Stoll; T. Sugitate; C. Suire; A. Sukhanov; J. Sziklai; E. M. Takagui; A. Taketani; R. Tanabe; Y. Tanaka; S. Taneja; K. Tanida; M. J. Tannenbaum; S. Tarafdar; A. Taranenko; P. Tarján; H. Themann; D. Thomas

    2010-01-01

    We present measurements of J\\/psi yields in d+Au collisions at sqrt(s_NN) =\\u000a200 GeV recorded by the PHENIX experiment and compare with yields in p+p\\u000acollisions at the same energy per nucleon-nucleon collision. The measurements\\u000acover a large kinematic range in J\\/psi rapidity (-2.2 < y < 2.4) with high\\u000astatistical precision and are compared with two theoretical models: one

  2. Environmental control of cold hardiness in woody plants.

    PubMed

    Irving, R M; Lanphear, F O

    1967-09-01

    The development of cold hardiness in 2 woody plant species (Acer negundo and Viburnum plicatum tomentosum) was shown to be independent of the induction of bud dormancy. Substantial hardiness levels were obtained under controlled conditions with long days and certain low temperatures-without dormancy development as a prerequisite.Low temperatures given during the dark period with long days induced hardiness to a level not significantly different from that of short days. Giving plants continuous 10 degrees temperatures under long days forced plants to harden as if they were under short days, even though they were not dormant.Development of hardiness was shown to be a photoperiodic response. Increasing weeks of short days, followed by a low temperature hardening period in darkness, brought about a progressive increase in hardiness. The short day stimulus could be reversed by long days. Following 6 weeks of short days, the rate of hardening in darkness at 5 degrees was over twice that of plants previously exposed to long days. PMID:16656639

  3. Effect of cold-work and annealing on the anelasticity of L62 [62% Cu] brass

    Microsoft Academic Search

    S. O. Tsobkallo; Z. A. Vashchenko

    1959-01-01

    1.Reheating of work-hardened brass L62 at 200–250° C increases the elastic limit and reduces (down to 1\\/16) the direct elastic after-effect while increasing its reversibility.2.Contrary to the behavior of the elastic limit and elastic after-effect, the tensile strength, elongation at fracture, and hardness of heavily cold worked (up to 58%) L62 brass, do not have significant extreme values affected by

  4. Nanoscale characterization of the biomechanical hardening of bovine zona pellucida

    PubMed Central

    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

    2012-01-01

    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

  5. Cold fusion, Alchemist's dream

    SciTech Connect

    Clayton, E.D.

    1989-09-01

    In this report the following topics relating to cold fusion are discussed: muon catalysed cold fusion; piezonuclear fusion; sundry explanations pertaining to cold fusion; cosmic ray muon catalysed cold fusion; vibrational mechanisms in excited states of D{sub 2} molecules; barrier penetration probabilities within the hydrogenated metal lattice/piezonuclear fusion; branching ratios of D{sub 2} fusion at low energies; fusion of deuterons into {sup 4}He; secondary D+T fusion within the hydrogenated metal lattice; {sup 3}He to {sup 4}He ratio within the metal lattice; shock induced fusion; and anomalously high isotopic ratios of {sup 3}He/{sup 4}He.

  6. On the calibration of the Chaboche hardening model and a modified hardening rule for uniaxial ratcheting prediction

    Microsoft Academic Search

    Mohamad Rezaiee-Pajand; Sina Sinaie

    2009-01-01

    A systematic mathematical approach is developed in the context of uniaxial cyclic ratcheting for the parameter determination of the decomposed Chaboche hardening rule. This is achieved by deriving the relation between the evolution of the backstress and the plastic strain accumulation. Unlike current calibration techniques where a trial–error approach is employed to fit the simulation results to experimental data, the

  7. Is It a Cold or the Flu? Symptoms Cold Flu

    E-print Network

    Bandettini, Peter A.

    Is It a Cold or the Flu? Symptoms Cold Flu Fever Rare Usual; high (100°F to 102°F, occasionally with a cold Annual vaccination; antiviral medicines--see your doctor Complications Sinus congestion Middle ear

  8. Strain Hardening and Size Effect in Five-fold Twinned Ag Nanowires.

    PubMed

    Narayanan, Sankar; Cheng, Guangming; Zeng, Zhi; Zhu, Yong; Zhu, Ting

    2015-06-10

    Metallic nanowires usually exhibit ultrahigh strength but low tensile ductility owing to their limited strain hardening capability. Here we study the unique strain hardening behavior of the five-fold twinned Ag nanowires by nanomechanical testing and atomistic modeling. In situ tensile tests within a scanning electron microscope revealed strong strain hardening behavior of the five-fold twinned Ag nanowires. Molecular dynamics simulations showed that such strain hardening was critically controlled by twin boundaries and pre-existing defects. Strain hardening was size dependent; thinner nanowires achieved more hardening and higher ductility. The size-dependent strain hardening was found to be caused by the obstruction of surface-nucleated dislocations by twin boundaries. Our work provides mechanistic insights into enhancing the tensile ductility of metallic nanostructures by engineering the internal interfaces and defects. PMID:25965858

  9. A micro-mechanical evaluation of the effects of die hardener on die stone.

    PubMed

    He, Li-Hong; van Vuuren, Ludwig Jansen; Planitz, Nina; Swain, Michael V

    2010-08-01

    The purpose of this study was to investigate the properties of a die hardener penetrated layer and evaluate its protective effects on the surface of die stone. A commercial die hardener (PDQ die hardener, Whipmix corp., USA) was tested on a die stone (GC Fujirock EP die stone, GC Europe, Belgium) and a dental plaster (Dental Stone, United States Gypsum Company, USA). Nanoindentation and micro-scratch tests were performed on both coated and uncoated specimens. The scratch damage was observed by SEM and the penetration depth of die hardener was detected by the affiliated EDX. Upon drying, the die hardener penetrated into the die stone to a depth of 3-5 microm, and deposited a thin film on the surface of die stone. Although the die hardener penetrated layer did not show improved mechanical properties, the die hardener film on the surface did protect the specimens from abrasion damage. PMID:20657152

  10. Surface hardening of titanium alloys with melting depth controlled by heat sink

    DOEpatents

    Oden, Laurance L. (Albany, OR); Turner, Paul C. (Albany, OR)

    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.

  11. Cold-adapted archaea

    Microsoft Academic Search

    Ricardo Cavicchioli

    2006-01-01

    Many archaea are extremophiles. They thrive at high temperatures, at high pressure and in concentrated acidic environments. Nevertheless, the largest proportion and greatest diversity of archaea exist in cold environments. Most of the Earth's biosphere is cold, and archaea represent a significant fraction of the biomass. Although psychrophilic archaea have long been the neglected majority, the study of these microorganisms

  12. Ultra-Cold Molecules

    Microsoft Academic Search

    A. Fioretti; M. Fazzi; M. Mazzoni; T. Ban; C. Gabbanini

    2004-01-01

    In this paper we overview recent results on the formation of translationally cold molecules. While there are some methods relying on direct cooling of molecules, we shall concentrate on the photoassociation technique that starts from laser-cooled atoms. The detection methods for the ultra-cold molecules will be presented together with a report on the trapping techniques. The treatment is mainly focused

  13. Cold Air Damming

    NSDL National Science Digital Library

    2014-09-14

    Cold Air Damming is part of the Mesoscale Meteorology Primer series. This module first presents a Navy forecast scenario prior to the development of a major cold air damming (CAD) event along the east slopes of the Appalachian Mountains. Then, from a conceptual standpoint, the classic CAD scenario is described in detail, both from an observational and modeling standpoint.

  14. Springback investigation of anisotropic aluminum alloy sheet with a mixed hardening rule and Barlat yield criteria in sheet metal forming

    Microsoft Academic Search

    Bingtao Tang; Xiaoyang Lu; Zhaoqing Wang; Zhen Zhao

    2010-01-01

    A mixed hardening model has been implemented based on Lemaitre and Chaboche non-linear kinematic hardening theory to consider cyclic behavior and the Bauschinger effect. The Chaboche isotropic hardening theory is incorporated into the non-linear kinematic hardening model to introduce a surface of nonhardening in the plastic strain space. The bending and reverse bending case study has verified the effectiveness of

  15. RAPID SOLUTION HARDENING AT ELEVATED TEMPERATURES BY SUBSTITUTIONAL Re ALLOYING IN

    E-print Network

    -based structural intermetallic alloys for very high temperature applications (01200±16008C). # 2000 Acta Metal- lurgica Inc. Published by Elsevier Science Ltd. All rights reserved. Keywords: Intermetallics is a potential material for high temperature structural applications primarily due to its high melting point

  16. Age hardening in rapidly solidified and hot isostatically pressed beryllium-aluminum-silver alloys

    SciTech Connect

    Carter, D.H.; McGeorge, A.C.; Jacobson, L.A.; Stanek, P.W.

    1995-07-01

    Three different alloys of beryllium, aluminum and silver were processed to powder by centrifugal atomization in a helium atmosphere. Alloy compositions were, by weight, 50% Be, 47.5% Al, 2.5% Ag, 50% Be, 47% Al, 3% Ag, and 50% Be, 46% Al, 4% Ag. Due to the low solubility of both aluminum and silver in beryllium, the silver was concentrated in the aluminum phase, which appeared to separate from the beryllium in the liquid phase. A fine, continuous composite beryllium-aluminum microstructure was formed, which did not significantly change after hot isostatically pressing at 550 C for one hour at 30,000 psi argon pressure. Samples of HIP material were solution treated at 550 C for one hour, followed by a water quench. Aging temperatures were 150, 175, 200 and 225 C for times ranging from one half hour to 65 hours. Hardness measurements were made using a diamond pyramid indenter with a load of 1 kg. Results indicate that peak hardness was reached in 36--40 hours at 175 C and 12--16 hours at 200 C aging temperature, relatively independent of alloy composition.

  17. Transformation hardening of steel sheet for automotive applications

    NASA Astrophysics Data System (ADS)

    Takechi, H.

    2008-12-01

    Among high-strength steels, transformation hardening steels such as dual-phase (DP) steel and transformation-induced plasticity (TRIP) steel offer a superior relationship between tensile strength (TS) and elongation (El) on a commercial scale. As demand has grown for lighter-weight automobiles, so also has the demand for higher TS, lower yield ratio, and higher hole expansion ratio grown. Recently DP steel has been developed with precipitation hardening and grain refining by TiC. A new TRIP steel composed of 5Mn-2Si and control-rolled with niobium addition suggests the formation of retained austenite ( ? R ) as much as 30% and TS × El = 3,000 kgf/mm2·%.

  18. Magnetic hardening in FePt nanostructured films

    SciTech Connect

    Liu, J.P.; Liu, Y.; Luo, C.P.; Shan, Z.S.; Sellmyer, D.J. [Behlen Laboratory of Physics and Center for Materials Research and Analysis, University of Nebraska, Lincoln, Nebraska 68588-0113 (United States)] [Behlen Laboratory of Physics and Center for Materials Research and Analysis, University of Nebraska, Lincoln, Nebraska 68588-0113 (United States)

    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.}

  19. 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.

  20. CMOS inverter design-hardened to the total dose effect

    SciTech Connect

    Roche, F.M.; Salager, L. [Universite Montpellier II/CNRS (France). Lab. d`Informatique de Robotique et de Microelectronique] [Universite Montpellier II/CNRS (France). Lab. d`Informatique de Robotique et de Microelectronique

    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.

  1. Poromechanical behaviour of hardened cement paste under isotropic loading

    E-print Network

    Ghabezloo, Siavash; Guédon, Sylvine; Martineau, Francçois; Saint-Marc, Jérémie

    2008-01-01

    The poromechanical behaviour of hardened cement paste under isotropic loading is studied on the basis of an experimental testing program of drained, undrained and unjacketed compression tests. The macroscopic behaviour of the material is described in the framework of the mechanics of porous media. The poroelastic parameters of the material are determined and the effect of stress and pore pressure on them is evaluated. Appropriate effective stress laws which control the evolution of total volume, pore volume, solid volume, porosity and drained bulk modulus are discussed. A phenomenon of degradation of elastic properties is observed in the test results. The microscopic observations showed that this degradation is caused by the microcracking of the material under isotropic loading. The good compatibility and the consistency of the obtained poromechanical parameters demonstrate that the behaviour of the hardened cement paste can be indeed described within the framework of the theory of porous media.

  2. Beam-hardening in simulated X-ray tomography

    Microsoft Academic Search

    K. Ramakrishna; K. Muralidhar; P. Munshi

    2006-01-01

    Polychromatic X-ray sources are used universally in computerized tomography to obtain adequate intensity of photons. These sources, however, can produce some artifacts in the reconstructed image due to non-linearity. Beam-hardening is one such artifact, which produces false line integrals due the photon-energy dependence of the attenuation co-efficient.The present investigation deals with the process of estimating the equivalent monoenergetic data, m,

  3. 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.

  4. Sequential circuit design for radiation hardened multiple voltage integrated circuits

    DOEpatents

    Clark, Lawrence T. (Phoenix, AZ); McIver, III, John K. (Albuquerque, NM)

    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.

  5. An energy-based beam hardening model in tomography

    Microsoft Academic Search

    E. Van de Casteele; D. Van Dyck; J. Sijbers; E. Raman

    2002-01-01

    As a consequence of the polychromatic x-ray source, used in micro-computer tomography (µCT )a nd in medical CT, the attenuation is no longer a linear function of absorber thickness. If this nonlinear beam hardening effect is not compensated, the reconstructed images will be corrupted by cupping artefacts. In this paper, a bimodal energy model for the detected energy spectrum is

  6. Active media-based form hardening of tubes and profiles

    Microsoft Academic Search

    R. Neugebauer; F. Schieck

    2010-01-01

    New requirements from the automotive industry regarding light weight design request the realization of structural parts with\\u000a maximum strength over 1,000 MPa. On the other hand, demands concerning part complexity, function integration and part quality\\u000a become higher and higher. The press hardening technology of boron-manganese alloyed steel for blank based part applications\\u000a represent the state of the art. Typical applications are

  7. Work hardening in micropillar compression: In situ experiments and modeling

    Microsoft Academic Search

    D. Kiener; P. J. Guruprasad; S. M. Keralavarma; G. Dehm; A. A. Benzerga

    2011-01-01

    Experimental measurements and simulation results for the evolution of plastic deformation and hardening in micropillars are compared. The stress–strain response of high-symmetry Cu single crystals is experimentally determined using in situ micropillar compression. Discrete dislocation simulations are conducted within a two-dimensional plane-strain framework with the dislocations modeled as line singularities in an isotropic elastic medium. Physics-based constitutive rules are employed

  8. Age-Hardenable Electrical Contact-Spring Material

    Microsoft Academic Search

    S. McRickard

    1969-01-01

    There is at present no satisfactory material available that can comply with all three of the most important criteria of a make-break spring contact, i.e. good spring properties, switching capability, and contact-resistance stability. As the result of a development program, a monolithic contact-spring material, composed of an age-hardening silver-palladium-copper alloy that satisfied these criteria was devised. The background theory and

  9. 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.

  10. Physical structure of hardened cement paste. A classical approach

    Microsoft Academic Search

    Torben C. Hansen

    1986-01-01

    It is explained how the classical model of the structure of hardened Portland cement paste was deduced by T.C. Powers and\\u000a coworkers from data on water vapor adsorption isotherms. Moreover, it is shown how the fractional volumes of all major constituents\\u000a in the physical structure of room temperature cured Portland cement paste can be estimated from information on water-cement\\u000a ratio

  11. Maximum norm wellposedness of nonlinear kinematic hardening models

    NASA Astrophysics Data System (ADS)

    Brokate, Martin; Krej?í, Pavel

    The Chaboche model represents a widely popular rate independent elastoplastic stress-strain law of nonlinear kinematic hardening type. We consider it as a special case of a certain system of ordinary differential equations coupled to a hysteresis nonlinearity which expresses the principle of maximal dissipation of energy. For this system, we prove wellposedness with respect to the maximum norm, that is, continuous dependence of the stress on the strain (or vice versa) with respect to perturbations of small amplitude.

  12. Structure of Age-Hardened Aluminium-Copper Alloys

    Microsoft Academic Search

    André Guinier

    1938-01-01

    WE have made X-ray diagrams of aluminium-copper alloys (5 per cent Cu) age-hardened at various temperatures (25°-200° C.); the samples were composed of large crystals, and the radiation was made monochromatic by reflection by a crystal. In a previous paper1, we described a new phenomenon which appeared in these diagrams: streaks of various length issuing from the centre, which we

  13. Work hardening as a strengthening mechanism in periodic cellular materials

    Microsoft Academic Search

    E. Bele; B. A. Bouwhuis; G. D. Hibbard

    2008-01-01

    Periodic cellular materials (PCMs) can be fabricated using perforation-stretching methods to produce 3D microtruss structures that have greater architectural efficiency than conventional metal foams. These methods can also introduce significant work hardening. However, the elevated temperatures of the subsequent joining step typically used to create a sandwich panel (e.g., brazing), means that much of the induced strengthening is lost. The

  14. 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.

  15. 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.

  16. Strain hardening behavior of ARMCO iron processed by ECAP

    NASA Astrophysics Data System (ADS)

    Muñoz Bolaños, J. A.; Higuera Cobos, O. F.; Cabrera Marrero, J. M.

    2014-08-01

    The strain hardening behavior of an ARMCO iron processed by ECAP at room temperature up to sixteen passes following route Bc was investigated through Hollomon and differential Crussard-Jaoul models. Results indicate that the Hollomon analysis shows some deviations from the experimentally determined true stress - true strain curves while the differential Crussard-Jaoul analysis based on the Ludwik equation and the modified Crussard- Jaoul analysis based on the Swift equation fit better when two work hardening exponents are considered. As expected, the strength of the material increased with the number of ECAP passes. Indeed the ultimate tensile stress reached a maximum of ~900MPa after 16 passes, which is more than three times higher than the UTS of the annealed material. Nevertheless, the strain hardening capacity of the material was reduced in comparison with the material without severe plastic deformation. For that reason the tensile ductility was also reduced at increasing ECAP passes. The increase in strength was attributed to the reduction of the grain size through refined sub-grains with high density of dislocations. After sixteenth passes the original grain size (namely 70 mm) was reduced down to 300 to 400 nm observing a good correspondence with the Hall-Petch relationship. The microstructural analysis, carried out by EBSD, showed an increasing amount in the fraction of high Angle Grain Boundaries (HAGB) after 1 pass due to the regeneration of the microstructure with a smaller grain size.

  17. Prescription Drugs and Cold Medicines

    MedlinePLUS

    ... Drugs of Abuse » Prescription Drugs & Cold Medicines Prescription Drugs & Cold Medicines Email Facebook Twitter What is Prescription Drug Abuse: Some medications have psychoactive (mind-altering) properties ...

  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 ? 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 ?. 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. Effect of cooling method during hardening of a thermally stable bearing steel on its properties and bearing life

    Microsoft Academic Search

    L. Ya. Konter; V. L. Zakharova

    1984-01-01

    1.By varying the cooling during hardening it is possible to control the austenite content in secondary-hardening steel 8Kh4V9F2-Sh before dispersion hardening proceeding during isothermal soaking or tempering.2.With an increase in austenite content to 50% before dispersion hardening the hardness and strength of steel 8Kh4V9F2-Sh increases with retention of toughness and structural and dimensional stability.3.During hardening of articles made of steel

  20. Effect of Hf on structure and age hardening of Ti–Al-N thin films

    PubMed Central

    Rachbauer, R.; Blutmager, A.; Holec, D.; Mayrhofer, P.H.

    2012-01-01

    Protective coatings for high temperature applications, as present e.g. during cutting and milling operations, require excellent mechanical and thermal properties during work load. The Ti1 ? xAlxN system is industrially well acknowledged as it covers some of these requirements, and even exhibits increasing hardness with increasing temperature in its cubic modification, known as age hardening. The thermally activated diffusion at high temperatures however enables for the formation of wurtzite AlN, which causes a rapid reduction of mechanical properties in Ti1 ? xAlxN coatings. The present work investigates the possibility to increase the formation temperature of w-AlN due to Hf alloying up to 10 at.% at the metal sublattice of Ti1 ? xAlxN films. Ab initio predictions on the phase stability and decomposition products of quaternary Ti1 ? x ? yAlxHfyN alloys, as well as the ternary Ti1 ? xAlxN, Hf1 ? xAlxN and Ti1 ? zHfzN systems, facilitate the interpretation of the experimental findings. Vacuum annealing treatments from 600 to 1100 °C indicate that the isostructural decomposition, which is responsible for age hardening, of the Ti1 ? x ? yAlxHfyN films starts at lower temperatures than the ternary Ti1 ? xAlxN coating. However, the formation of a dual phase structure of c-Ti1 ? zHfzN (with z = y/(1 ? x)) and w-AlN is shifted to ~ 200 °C higher temperatures, thus retaining a film hardness of ~ 40 GPa up to ~ 1100 °C, while the Hf free films reach the respective hardness maximum of ~ 38 GPa already at ~ 900 °C. Additional annealing experiments at 850 and 950 °C for 20 h indicate a substantial improvement of the oxidation resistance with increasing amount of Hf in Ti1 ? x ? yAlxHfyN. PMID:22319223

  1. Isocurvature cold dark matter fluctuations

    NASA Technical Reports Server (NTRS)

    Efstathiou, G.; Bond, J. R.

    1986-01-01

    According to Preskill et al. (1983), the axion field represents a particularly attractive candidate for the dark matter in the universe. In many respects it behaves like other forms of cold dark matter, such as massive gravitinos, photinos, and monopoles. It is, however, a pseudo-Goldstone boson of very low mass, and it is only because of rapid coherent oscillations of the field that it can dominate the mass density of the universe. In the present paper it is assumed that the isocurvature mode is dominant. The linear evolution calculations conducted do not depend upon specific details of particle physics. For this reason, the conducted discussion is applicable to any cold dark matter model with isocurvature perturbations. The results of the study lead to the conclusion that scale-invariant isocurvature perturbations do not seem an attractive possibility for the origin of large-scale structure. The findings strengthen the review that primordial adiabatic perturbations were the dominant fluctuations in the early stages of the Big Bang.

  2. Cold Sores (HSV-1)

    MedlinePLUS

    ... anywhere on the body, including the genital area. Genital herpes isn't typically caused by HSV-1; it's ... Parents MORE ON THIS TOPIC Can You Get Genital Herpes From a Cold Sore? Mononucleosis Genital Herpes Tips ...

  3. Colds and the Flu

    MedlinePLUS

    ... with green- or yellow-colored discharge) Sore throat Cough Sneezing Fatigue Muscle aches Headache Watery eyes Cold ... aches, especially in your back, arms and legs Cough Headache Loss of appetite What is H1N1 flu? ...

  4. Cold hardiness in molluscs

    NASA Astrophysics Data System (ADS)

    Ansart, Armelle; Vernon, Philippe

    2003-05-01

    Molluscs inhabit all types of environments: seawater, intertidal zone, freshwater and land, and of course may have to deal with subzero temperatures. Ectotherm animals survive cold conditions by avoiding it by extensive supercooling (freezing avoidant species) or by bearing the freezing of their extracellular body fluids (freezing tolerant species). Although some studies on cold hardiness are available for intertidal molluscs, they are scarce for freshwater and terrestrial ones. Molluscs often exhibit intermediary levels of cold hardiness, with a moderate or low ability to supercool and a limited survival to the freezing of their tissues. Several factors could be involved: their dependence on water, their ability to enter dormancy, the probability of inoculative freezing in their environment, etc. Size is an important parameter in the development of cold hardiness abilities: it influences supercooling ability in land snails, which are rather freezing avoidant and survival to ice formation in intertidal organisms, which generally tolerate freezing.

  5. A rapid cyclic voltammetric method for studying cement factors affecting the corrosion of reinforced concrete

    SciTech Connect

    Foulkes, F.R.; McGrath, P. (Univ. of Toronto, Ontario (Canada))

    1999-06-01

    A rapid cyclic voltammetric method for studying the influence of cement factors on the corrosion of embedded iron and steel in hardened cement paste is described. The technique employs a cement electrode'' consisting of an iron or steel wire embedded in a miniature cylinder of hardened cement paste. The rapid cyclic voltammetric method is fast, reproducible, and provides information on the corrosiveness of the pore solution environment surrounding the embedded metal. The usefulness of the method is demonstrated by showing how it can be used to evaluate the threshold chloride content of hardened ordinary portland cement paste at which corrosion begins and by using it to evaluate the relative efficacy of several admixed corrosion inhibitors.

  6. Transmission of colds

    Microsoft Academic Search

    Diane E. Pappas; J. Owen Hendley

    Rhinorrhea, nasal congestion, and sore throat herald the beginning of the cold season for both children and adults. Although\\u000a the common cold is a self-limited infection, there are no effective treatments presently available and complications, missed\\u000a time from work and school, and overall discomfort are not insignificant. Understanding how infections are transmitted may\\u000a lead to interventions to reduce rates of

  7. Rapid Response

    NSDL National Science Digital Library

    Rapid Response, a "knowledge resource specializing in policy advice for developing countries," is a new service from the World Bank. Mainly a fee-based service, the Rapid Response service also contains several valuable free resources. The service concentrates on several areas of expertise including investment climates; private participation in a variety of complex sectors such as telecommunications, water, and energy; and output-based aid. By far, the most useful tool offered on this site is Knowledge Resources, the database of papers, reports, case studies and related Websites. The database is searchable by keyword or by topic or resource type.

  8. Anisotropy of Dynamic Compressive Properties of Non-Heat-Treating Cold-Heading-Quality Steel Bars

    NASA Astrophysics Data System (ADS)

    Kim, Hyunmin; Kang, Minju; Bae, Chul Min; Kim, Hyoung Seop; Lee, Sunghak

    2014-01-01

    In the current study, a non-heat-treating cold-heading-quality steel bar was fabricated by cold drawing of a rolled bar, and anisotropic mechanical properties of the as-rolled and cold-drawn bars were investigated by quasistatic and dynamic compressive tests of 0 deg (longitudinal)-, 45 deg-, and 90 deg (transverse)-orientation specimens. Under the dynamic compressive loading, the trend of strength variation was similar to that of the quasistatic compressive loading, while the strength level was considerably increased by the strain rate hardening effect. Stress-strain curves of the cold-drawn bar specimens showed the nearly same strain hardening behavior, irrespective of specimen orientation and strain rate, but the yield stress and compressive flow stress increased in the order of the 0 deg-, 90 deg-, and 45 deg-orientation specimens. In the 45 deg- and 90 deg-orientation specimens, the pearlite bands had the stronger resistance to the stress acting on the maximum shear stress plane than in the 0 deg-orientation specimens, thereby resulting in the higher strengths. In some dynamically compressed specimens, pearlite bands were dissolved to form bainitic microstructures. Locations of these bainitic microstructures were well matched with hemispherical-shaped heat-trap zones, which confirmed that bainitic microstructures were formed by the temperature rise occurring during the dynamic compressive loading.

  9. Method for increasing the rate of compressive strength gain in hardenable mixtures containing fly ash

    SciTech Connect

    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.

  10. Method for increasing the rate of compressive strength gain in hardenable mixtures containing fly ash

    DOEpatents

    Liskowitz, John W. (Belle Mead, NJ); Wecharatana, Methi (Parsippany, NJ); Jaturapitakkul, Chai (Bangkok, TH); Cerkanowicz, deceased, Anthony E. (late of Livingston, NJ)

    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.

  11. 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.

  12. Improved impact toughness of 13Cr martensitic stainless steel hardened by laser

    NASA Astrophysics Data System (ADS)

    Tsay, L. W.; Chang, Y. M.; Torng, S.; Wu, H. C.

    2002-08-01

    The impact toughness of AISI 403 martensitic stainless steel plate and laser-hardened specimens tempered at various temperatures were examined. Phosphorus was the primary residual impurity responsible for tempered embrittlement of this alloy. The experimental result also indicated that AISI 403 stainless steel was very sensitive to reverse-temper embrittlement. The improved impact toughness of the laser-hardened specimen was attributed to the refined microstructure in the laser-hardened zone.

  13. Improved Adaptation to Cold-Shock, Stationary-Phase, and Freezing Stresses in Lactobacillus plantarum Overproducing Cold-Shock Proteins

    PubMed Central

    Derzelle, Sylviane; Hallet, Bernard; Ferain, Thierry; Delcour, Jean; Hols, Pascal

    2003-01-01

    We have investigated the effect of overproducing each of the three cold shock proteins (CspL, CspP, and CspC) in the mesophilic lactic acid bacterium Lactobacillus plantarum NC8. CspL overproduction transiently alleviated the reduction in growth rate triggered by exposing exponentially growing cells to cold shock (8°C), suggesting that CspL is involved in cold adaptation. The strain overproducing CspC resumed growth more rapidly when stationary-phase cultures were diluted into fresh medium, indicating a role in the adaptation and recovery of nutritionally deprived cells. Overproduction of CspP led to an enhanced capacity to survive freezing. PMID:12839816

  14. Measurement of Water Transport from Saturated Pumice Aggregates to Hardening Cement Paste

    E-print Network

    Bentz, Dale P.

    Measurement of Water Transport from Saturated Pumice Aggregates to Hardening Cement Paste by Pietro-ray absorption showed that considerable transport of water from saturated lightweight aggregates (pumice

  15. Detection of cold pain, cold allodynia and cold hyperalgesia in freely behaving rats

    Microsoft Academic Search

    Andrew J Allchorne; Daniel C Broom; Clifford J Woolf

    2005-01-01

    BACKGROUND: Pain is elicited by cold, and a major feature of many neuropathic pain states is that normally innocuous cool stimuli begin to produce pain (cold allodynia). To expand our understanding of cold induced pain states we have studied cold pain behaviors over a range of temperatures in several animal models of chronic pain. RESULTS: We demonstrate that a Peltier-cooled

  16. BUSFET - A Novel Radiation-Hardened SOI Transistor

    SciTech Connect

    Schwank, J.R.; Shaneyfelt, M.R.; Draper, B.L.; Dodd, P.E.

    1999-07-20

    The total-dose hardness of SOI technology is limited by radiation-induced charge trapping in gate, field, and SOI buried oxides. Charge trapping in the buried oxide can lead to back-channel leakage and makes hardening SOI transistors more challenging than hardening bulk-silicon transistors. Two avenues for hardening the back-channel are (1) to use specially prepared SOI buried oxides that reduce the net amount of trapped positive charge or (2) to design transistors that are less sensitive to the effects of trapped charge in the buried oxide. In this work, we propose a new partially-depleted SOI transistor structure that we call the BUSFET--Body Under Source FET. The BUSFET utilizes a shallow source and a deep drain. As a result, the silicon depletion region at the back channel caused by radiation-induced charge trapping in the buried oxide does not form a conducting path between source and drain. Thus, the BUSFET structure design can significantly reduce radiation-induced back-channel leakage without using specially prepared buried oxides. Total dose hardness is achieved without degrading the intrinsic SEU and dose rate hardness of SOI technology. The effectiveness of the BUSFET structure for reducing total-dose back-channel leakage depends on several variables, including the top silicon film thickness and doping concentration and the depth of the source. 3-D simulations show that for a doping concentration of 10{sup 18} cm{sup {minus}3} and a source depth of 90 nm, a silicon film thickness of 180 nm is sufficient to almost completely eliminate radiation-induced back-channel leakage. However, for a doping concentration of 3x10{sup 17} cm{sup {minus}3}, a thicker silicon film (300 nm) must be used.

  17. X-ray beam hardening correction by minimizing reprojection distance

    NASA Astrophysics Data System (ADS)

    Kingston, Andrew M.; Myers, Glenn R.; Varslot, Trond K.

    2012-10-01

    We address the problem of tomographic image quality degradation due to the effects of beam hardening when using a polychromatic X-ray source. Beam hardening refers to the preferential attenuation of low-energy (or soft) X-rays resulting in a beam with a higher average energy (i.e., harder). In projection images, thin or low-Z materials appear more dense relative to thick or higher-Z materials. This misrepresentaion produces artifacts in the reconstructed image such as cupping and streaking. Our method involves a post-acquisition software correction that applies a beam-hardening correction curve to remap the linearised projection intensities. The curve is modelled by an eighth-order polynomial and assumes an average material for the object. The process to determine the best correction curve requires precisely 8 reconstructions and re-projections of the experiment data. The best correction curve is defined as that which generates a projection set p that minimises the reprojection distance. Reprojection distance is defined as the L2 norm of the difference between p, a set of projections, and RR†p, the result after p is reconstructed and then reprojected, i.e., ?RR†p - p?2. Here R denotes the projection operator and R† is its Moore-Penrose pseudoinverse, i.e., the reconstruction operator. This technique was designed for single-material objects and in this case the calculated curve matches that determined experimentally. However, this technique works very well for multiple-material objects where the resulting curve is a kind of average of all materials present. We show that this technique corrects for both cupping and streaking in tomographic images by including several experimental examples. Note that this correction method requires no knowledge of the X-ray spectrum or materials present and can therefore be applied to old data sets.

  18. Bulk-hardened magnets based on Y2Co17

    NASA Astrophysics Data System (ADS)

    Gabay, A. M.; Zhang, Y.; Hadjipanayis, G. C.

    2001-07-01

    Bulk magnetic hardening of cast Y2Co17-based alloys was systematically studied for different compositions and heat treatments. Additions of Cu and Zr, Hf, or Ti to the Y-Co were found to be essential for developing coercivity. The performance of Y-Co-Cu-Zr magnets can be significantly improved by partial Pr and Fe substitutions for Y and Co, respectively. Anisotropic (Y0.8Pr0.2)11.5Zr2.75Co56.75Fe14Cu15 powders with intrinsic coercivity of 7.8 kOe and energy product of 14.4 MG Oe were obtained after annealing at 900 °C for 15 min and cooling to 200 °C at the rate of 4 °C/min. We also explored the effects of some other rare earths (La, Nd, Gd) and transition metals (Mn, Ni) on the magnetic properties of the Y-Co-Cu-Zr magnets. The phases present and the microstructure were analyzed with x-ray diffraction, thermomagnetic analysis, and transmission electron microscopy. The cellular/lamellar microstructure of the bulk-hardened alloys is similar to that of Sm-Co-Cu-Zr magnets. Among the most noticeable distinctions in the Y-Co-Cu-Zr alloys are a smaller average size of 2:17 cells and a variety of Zr-rich phases, like Zr2Co11 and Zr6Co23. Although the Y2Co17 phase is known to have an "easy-plane" anisotropy, the x-ray diffraction experiments with magnetically oriented powders suggest that in the bulk-hardened Y-Co-Cu-Zr and Y-Co-Cu-Fe-Zr magnets the 2:17 phase has uniaxial anisotropy.

  19. Case depth verification of hardened samples with Barkhausen noise sweeps

    SciTech Connect

    Santa-aho, Suvi; Vippola, Minnamari; Lepistö, Toivo [Tampere University of Technology, Department of Materials Science, P.O. Box 589, 33101 Tampere (Finland); Hakanen, Merja [Stresstech Oy, Tikkutehtaantie 1, 40800 Vaajakoski (Finland); Sorsa, Aki; Leiviskä, Kauko [University of Oulu, Control Engineering Laboratory, P.O. Box 4300, FIN-90014 University of Oulu (Finland)

    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.

  20. EMP hardening featuring interactive graphics and computer-aided design

    NASA Astrophysics Data System (ADS)

    White, D. R. J.; Mardiguian, M.

    This paper summarizes recent advances in EMI control methodology and procedures with applications featuring computer-aided design (CAD) and interactive graphics (IAG). An example illustrates electronic system design and/or retrofit to harden against electromagnetic pulse (EMP) threats. The purpose of this paper is three-fold: (1) to present an electromagnetic interference (EMI) control methodology and procedure; (2) to illustrate the state-of-the-art in electromagnetic compatibility (EMC) CAD; and (3) to portray the educational value offered by IAG/CAD-type programs.

  1. Rapid Manufacturing

    Microsoft Academic Search

    Bahram Asiabanpour; Alireza Mokhtar; Mahmoud Houshmand

    \\u000a This chapter defines rapid manufacturing (RM) as a technique for manufacturing solid objects by the sequential delivery of\\u000a energy and\\/or material to specified points in space. Current practice is to control the manufacturing process by using a computer-generated\\u000a mathematical model. This chapter compares the large speed and cost advantages of RM to alternative polymer or metal manufacturing\\u000a techniques such as

  2. Cold Regions Bibliography

    NSDL National Science Digital Library

    A joint endeavor of the Federal Research Division of the Library of Congress and the US Army Cold Regions Research and Engineering Laboratory (CRREL), this project disseminates information on Antarctica and cold regions science and technology "by maintaining and continually updating a database which is an accumulation of over 40 years of materials on the science and technology of the world's cold regions." This database currently contains over 208,000 records, with about 6,000 accessions annually. After entering a supplied user id and password, users can search the database by keyword, author, or year of publication. Search returns include title, source, and a link to more information, including pages, notes, series, and publisher information. A DOS version of the database is also available for limited periods to qualified researchers. More information is available at the site.

  3. Cold asymmetrical fermion superfluids

    SciTech Connect

    Caldas, Heron

    2003-12-19

    The recent experimental advances in cold atomic traps have induced a great amount of interest in fields from condensed matter to particle physics, including approaches and prospects from the theoretical point of view. In this work we investigate the general properties and the ground state of an asymmetrical dilute gas of cold fermionic atoms, formed by two particle species having different densities. We have show in a recent paper, that a mixed phase composed of normal and superfluid components is the energetically favored ground state of such a cold fermionic system. Here we extend the analysis and verify that in fact, the mixed phase is the preferred ground state of an asymmetrical superfluid in various situations. We predict that the mixed phase can serve as a way of detecting superfluidity and estimating the magnitude of the gap parameter in asymmetrical fermionic systems.

  4. Investigation into springback characteristics of two HSS sheets during cold v-bending

    SciTech Connect

    Fang, Gang; Gao, Wei-Ran [Department of Mechanical Engineering, Tsinghua University, Beijing 100084 (China)

    2013-12-16

    Considering the safety and the light-weight structure, there is an increasing requirement of high strength steel (HSS) sheets in the automotive industry. The high-precise prediction of the springback depends on constitutive equations and their corresponding material parameters. In order to investigate the springback of HSS sheets, DP590 and B280VK, their constitutive behaviors were analyzed based on the sheet tension tests. With respect to the constitutive equation, the Voce model is more proper to two hot-rolled steels, DP590 and B280VK, than the Swift model. Two steels are all saturated hardening, and the degree of hardening decreases with the strain. The cold v-banding tests of two HSS sheets were carried out for evaluation of springback characteristics. Results of v-bending experiments showed that the springback angle increases with the bending along 45°, 90° and 0° to the rolling direction of steel in turn.

  5. Radiation hardening of a high voltage IC technology (BCDMOS)

    SciTech Connect

    Desko, J.C. Jr.; Darwish, M.N.; Dolly, M.C.; Goodwin, C.A. (AT and T Bell Labs., Reading, PA (USA)); Dawes, W.R. Jr. (Sandia National Labs., Albuquerque, NM (USA)); Titus, J.L. (Naval Weapons Support Center, Crane, IN (USA))

    1990-01-01

    PIC's (Power Integrated Circuits) are becoming increasingly important because they allow integration of high-voltage and high-current power transistors, precision linear control circuitry, and low-voltage logic gates on the same monolithic chip. Integration of power and control functions provide benefits in reduced weight and size, enhanced reliability, and lower costs over conventional designs using these same components packaged separately. However, commercial PIC technologies, including AT T's commercial BCDMOS technology, are susceptible to failure in radiation environments. The relative lack of radiation hardness of the AT T BCDMOS technology was previously reported at this conference. Radiation hardening of PIC technologies is significantly more difficult than for other IC technologies, primarily because of the integration of many different types of devices into the technology. To facilitate integration, different devices share processing sequences. Thus, no one device can be optimized independently of the remaining devices. Since each device has its own distinct radiation response, this adds another set of constraints on the optimization of the overall technology from the point of view of device performance and radiation response. The high-voltage requirements further complicates efforts to harden a PIC technology. Modifying one device to optimize one aspect of its performance can severely impact all the other devices in the technology. 4 refs., 5 figs.

  6. Folding and faulting of strain-hardening sedimentary rocks

    NASA Astrophysics Data System (ADS)

    Johnson, Arvid M.

    1980-02-01

    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.

  7. On crack closure of precipitation hardened steels in aqueous solution

    NASA Astrophysics Data System (ADS)

    Hamano, R.

    1989-06-01

    Fatigue crack propagation tests were carried out in air and in a 3.5 pct NaCl aqueous solution under cathodic potential of -0.85 V (Ag/AgCl) for aged-hardened high strength steel (Ni-Al-Cr-Mo-C steel). the emphasis in the study was placed on the crack closure behavior of age-hardened materials in air and in the NaCl aqueous solution. The degree of crack closure in air was dependent on the behavior of plastic deformation such as inhomogeneous or homogeneous slip under mixed modes I and II. The underaged material containing coherent precipitates with the matrix had a higher crack opening load in air, compared with the overaged steel containing incoherent precipitates with the matrix. The degrec of crack closure of the underaged material in the NaCl aqueous solution was lower than that in air and was similar to that of overaged materials in the NaCl aqueous solution. It was shown that the decreased crack closure level for the underaged material resulted from accelerated fatigue crack growth under mode I due to hydrogen embrittlement in the aqueous solution.

  8. Testing and Analysis of Full-Scale Creep-Rupture Experiments on Inconel Alloy 740 Cold-Formed Tubing

    NASA Astrophysics Data System (ADS)

    Shingledecker, J. P.; Pharr, G. M.

    2013-02-01

    Full-scale pressurized creep-rupture tests were conducted on Inconel® alloy 740 cold-formed tube bends to evaluate the effect of cold-work on the performance of tube bends for high-temperature creep applications. A new method of analysis is developed that can be used to simplify the complexities of structural (geometric) effects and material degradation due to cold-work. Results show that Inconel® alloy 740 behaves similarly to other age-hardenable nickel-based alloys subjected to cold-work prior to creep testing with large reductions in rupture life and ductility and a corresponding moderate increase in minimum creep rate. The results also demonstrate that the full-size test method can be a beneficial to understanding the performance of large components in service.

  9. Extraordinary strain hardening by gradient structure XiaoLei Wua,1

    E-print Network

    Zhu, Yuntian T.

    a hitherto unknown strategy to develop strong and ductile materials by architecting heterogeneous-turn and subsequent good retention of strain hardening rate. Strain hardening is critical for increasing the material of Mechanics, Chinese Academy of Sciences, Beijing 100190, China; b Department of Materials Science

  10. BEAM HARDENING CORRECTION VIA MASS ATTENUATION DISCRETIZATION Renliang Gu and Aleksandar Dogandzi

    E-print Network

    Dogandzic, Aleksandar

    ,ald}@iastate.edu ABSTRACT We develop a beam-hardening correction method for polychromatic x- ray computed tomography (ct Terms-- Beam hardening, computed tomography, signal re- construction, x-ray tomography. 1. INTRODUCTION . A standard approach to simulate the polychromatic x-ray computed tomography (ct) measurements

  11. A model-based correction method for beam hardening artefacts in X-ray tomography

    Microsoft Academic Search

    D Van Dyck; J Sijbers; E Raman

    The absorption law of Lambert-Beer gives rise to the linear relationship between the attenuation and the thickness of the material. However, this law is only true for a monochromatic beam. For polychromatic sources used in medical computer tomography (CT) and microtomography, this linear relationship no longer holds, which leads to beam hardening. When the beam hardening effect is not accounted

  12. A hierarchical multiscale modeling of precipitation hardened nickel-based superalloys

    E-print Network

    Zabaras, Nicholas J.

    A hierarchical multiscale modeling of precipitation hardened nickel-based superalloys Bin Wen1://mpdc.mae.cornell.edu/ Abstract. Nickel-based superalloys are extensively used in applications, such as turbine disks, requiring modeling, dislocation dynamics, precipitation hardening, nickel- based superalloys, crystal plasticity

  13. A Comparative Study of Two Methods for the Correction of Beam Hardening Artifacts in

    E-print Network

    Faridani, Adel

    for reducing such artifacts. A correction method proposed by Herman and Trivedi in 1985, and an iterative that may corrupt the x-ray image. Some artifacts are caused by the patient itself. For example, the motion that emits x-rays of multiple energies. This is called a beam hardening artifact. Reducing beam hardening

  14. Structure and mechanical properties of rails type R65 bulk-hardened in oil

    Microsoft Academic Search

    D. K. Nesterov; N. N. Razin'kova; L. E. Chernyakova; B. S. Kisil

    1991-01-01

    1.The nonuniformity of distribution of structure and properties over the section of the rail profile after hardening, and also after hardening and tempering by the technology of the Kuznetsk Metallurgical Combine is most distinct when the rail steel contains at least 0.76% C. Then the difference in hardness is characteristic of parts of the surface layer of the head on

  15. Fatigue Properties of Materials Surface Hardened by Plasma Nitriding and Laser Beam

    Microsoft Academic Search

    P. Mazal; I. Dlouhý; P. Stola?

    1997-01-01

    Carbon steel, standard bearing steel, grey cast iron, and structural steel, respectively, were used to determine the effect of laser transformation hardening and low temperature plasma nitriding on S-N (Wöhler's) curves. For all materials and treatment conditions examined, the homogeneity of the case hardened layers seems to be the most important factor that influences the fatigue crack nucleation, much more

  16. Finite element simulation of springback for a channel draw process with drawbead using different hardening models

    Microsoft Academic Search

    Aboozar Taherizadeh; Abbas Ghaei; Daniel E. Green; William J. Altenhof

    2009-01-01

    The objective of this work is to predict the springback of Numisheet’05 Benchmark#3 with different material models using the commercial finite element code ABAQUS. This Benchmark consisted of drawing straight channel sections using different sheet materials and four different drawbead penetrations. Numerical simulations were performed using Hill's 1948 anisotropic yield function and two types of hardening models: isotropic hardening (IH)

  17. Internal-variable constitutive model for rate-independent plasticity with hardening saturation surface

    Microsoft Academic Search

    P. Fuschi; C. Polizzotto

    1998-01-01

    Summary An elastic-plastic material model with internal variables and thermodynamic potential, not admitting hardening states out of a saturation surface, is presented. The existence of such a saturation surface in the internal variables space — a consequence of the boundedness of the energy that can be stored in the material's internal micro-structure — encompasses, in case of general kinematic\\/isotropic hardening,

  18. Reproduction studies in the rat with shea oleine and hardened shea oleine

    Microsoft Academic Search

    P Baldrick; J. A Robinson; P. A Hepburn

    2001-01-01

    Shea oleine is an oil fraction derived from the nut of the tree Butyrospermum parkii, which grows in central and western Africa. There are several uses of shea oleine including its use as a frying oil and, after hardening, in margarine and toffee fat. This investigation was performed to examine the toxicity of 7 or 15% hardened shea oleine in

  19. Cold spray nozzle design

    DOEpatents

    Haynes, Jeffrey D. (Stuart, FL); Sanders, Stuart A. (Palm Beach Gardens, FL)

    2009-06-09

    A nozzle for use in a cold spray technique is described. The nozzle has a passageway for spraying a powder material, the passageway having a converging section and a diverging section, and at least the diverging section being formed from polybenzimidazole. In one embodiment of the nozzle, the converging section is also formed from polybenzimidazole.

  20. Disinfestation with Cold

    Technology Transfer Automated Retrieval System (TEKTRAN)

    This book chapter by Neil Heather and Guy Hallman, in “Pest Management and Phytosanitary Trade Barriers,” CABI Press, reviews the history and current status of cold as a phytosanitary treatment and makes recommendations for future research. The recent problems with Mediterranean fruit fly in Clemen...

  1. Teaching "In Cold Blood."

    ERIC Educational Resources Information Center

    Berbrich, Joan D.

    1967-01-01

    The Truman Capote nonfiction novel, "In Cold Blood," which reflects for adolescents the immediacy of the real world, illuminates (1) social issues--capital punishment, environmental influence, and the gap between the "haves" and "have-nots," (2) moral issues--the complexity of man's nature, the responsibility of one man for another, and the place…

  2. Department of Mechanical Engineering Spring 2012 Cold Box Pressure Relief Device

    E-print Network

    Demirel, Melik C.

    PENNSTATE Department of Mechanical Engineering Spring 2012 Cold Box Pressure Relief Device Overview A cold box is a structural container used in the industrial gases industry. The main purpose of a box are released into the box if internal equipment leaks. A rapid increase in pressure may cause the box

  3. Dual-Frequency Approach to Assess Surface Hardened Layer Using NDE Technology

    NASA Astrophysics Data System (ADS)

    Kashefi, Mehrdad; Kahrobaee, Saeed

    2013-04-01

    Inspection and quality control of induction hardened parts require a good understanding of the depth of the hardened layer. Traditional destructive methods to determine the case depth are considered to be costly and time-consuming. The eddy current (EC) technique is sensitive to micro-structural changes; hence, it can be used to determine the case depth based on the differences in magnetic properties between the hardened layer and the core of the specimen. In this study, identical rods of AISI 1045 mild carbon steel were surface hardened using induction hardening technique. In order to investigate the applicability of the EC technique, the relations between obtained effective and total case depths and the EC outputs (induced voltage, normalized impedance, phase angle, and their harmonic characteristics) were studied. The results show a maximum of correlation coefficient of 94% in determining case depths by EC technique.

  4. 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.

  5. Emulsion gel beads of calcium pectinate capable of floating on the gastric fluid: effect of some additives, hardening agent or coating on release behavior of metronidazole.

    PubMed

    Sriamornsak, Pornsak; Thirawong, Nartaya; Puttipipatkhachorn, Satit

    2005-03-01

    Emulsion gel (EMG) beads of calcium pectinate capable of floating in the gastric condition were developed using an emulsion-gelation method and their release properties were investigated. Attempts to modify the drug release were made by applying some additives into the starting solution prior to bead formation, by hardening with glutaraldehyde, and by coating with polymer. The metronidazole-loaded EMG beads were found to float on simulated gastric fluid. Increasing the drug to pectin ratio in the beads slowed the drug release from the conventional and the EMG beads. However, the drug release from these beads was rapid, i.e., about 80% of drug loading released within 20-80 min. The additives (PEG10000, glyceryl monostearate and Eudragit L) had a slight, insignificant, effect on the drug release. Using 2% glutaraldehyde as a hardening agent prolonged the drug release. Coating the beads with Eudragit RL significantly sustained the drug release while the beads remained buoyant. The results suggest that EMG beads are suitable as a carrier for intragastric floating drug delivery and that their release behaviour could be modified by hardening with glutaraldehyde or by coating with Eudragit RL. PMID:15734303

  6. Thermal creep model for CWSR zircaloy-4 cladding taking into account the annealing of the irradiation hardening

    SciTech Connect

    Cappelaere, Chantal; Limon, Roger; Duguay, Chrstelle; Pinte, Gerard; Le Breton, Michel [CEA Saclay, DEN, Serv Etud Mat Irradies, F-91191 Gif Sur Yvette, (France); Bouffioux, Pol [EDF R et D Renardieres, F-77818 Ecuelles, Moret Sur Loing, (France); Chabretou, Valerie [AREVA NP SAS, AREVA, F-69456 Lyon 6, (France); Miquet, Alain [EDF SEPTEN, F-69628 Villeurbanne, (France)

    2012-02-15

    After irradiation and cooling in a pool, spent nuclear fuel assemblies are either transported for wet storage to a devoted site or loaded in casks for dry storage. During dry transportation or at the beginning of dry storage, the cladding is expected to be submitted to creep deformation under the hoop stress induced by the internal pressure of the fuel rod. The thermal creep is a potential mechanism that might lead to cladding failure. A new creep model was developed, based on a database of creep tests on as-received and irradiated cold-worked stress-relieved Zircaloy-4 cladding in a wide range of temperatures (310 degrees C to 470 degrees C) and hoop stress (80 to 260 MPa). Based on three laws-a flow law, a strain-hardening recovery law, and an annealing of irradiation hardening law this model allows the simulation of not only the transient creep and the steady-state creep, but also the early creep acceleration observed on irradiated samples tested in severe conditions, which was not taken into account in the previous models. The extrapolation of the creep model in the conditions of very long-term creep tests is reassuring, proving the robustness of the chosen formalism. The creep model has been assessed in progressively decreasing stress conditions, more representative of a transport. Set up to predict the cladding creep behavior under variable temperature and stress conditions, this model can easily be implemented into codes in order to simulate the thermomechanical behavior of spent fuel rods in various scenarios of postirradiation phases. (authors)

  7. Cold quark-gluon plasma and multiparticle production

    NASA Astrophysics Data System (ADS)

    Van Hove, L.

    1989-05-01

    We propose a mechanism for several unexpected particle production phenomena observed recently in high energy collisions and characterized by very low transverse momenta or intermittency-type fluctuations in longitudinal rapidity. It is based on a QCD parton shower model extended to very soft partons, leading to the formation of globs of very cold, nonthermal quark-gluon plasma.

  8. Review on Cold Spray Process and Technology: Part I—Intellectual Property

    Microsoft Academic Search

    Eric Irissou; Jean-Gabriel Legoux; Anatoly N. Ryabinin; Bertrand Jodoin; Christian Moreau

    2008-01-01

    The number of research papers as well as of patents and patent applications on cold spray and cold spray related technologies\\u000a has grown exponentially in the current decade. This rapid growth of activity brought a tremendous amount of information on\\u000a this technology in a short period of time. The main motivation for this review is to summarize the rapidly expanding

  9. Cold response of dedifferentiated barley cells at the gene expression, hormone composition, and freezing tolerance levels: studies on callus cultures.

    PubMed

    Vashegyi, Ildikó; Marozsán-Tóth, Zsuzsa; Galiba, Gábor; Dobrev, Petre I; Vankova, Radomira; Tóth, Balázs

    2013-06-01

    In this study, data is presented how dark-grown, embryogenic barley callus cells respond to cold without any light-dependent, chloroplast-related mechanism, independently of the systemic signals. The expression of HvCBF9, HvCBF14, and HvCOR14b genes, members of one of the most important cold-inducible regulatory system, was measured by real-time PCR. Characteristic of the cold response was similar in the crowns of seedlings and in dark-grown callus cultures, however, gene expression levels were lower in calli. Endogenous concentration of auxins, abscisic acid, and salicylic acid did not change, but phaseic acid and neophaseic acid showed robust accumulation after cold acclimation. Freezing tolerance of the cultures was also higher after 7 days of cold-hardening. The results suggest the presence of a basal, light-independent, cold-responsive activation of the CBF-COR14b pathway in barley cultures. The effects of Dicamba, the exogenous auxin analog used for maintaining tissue cultures were also studied. Dicamba seems to be a general enhancer of the gene expression and physiological responses to cold stress, but has no specific effect on the activation. Our data along with previous findings show that this system might be a suitable model for studying certain basic cellular mechanisms involved in the cold acclimation process in cereals. PMID:22669585

  10. Designing Security-Hardened Microkernels For Field Devices

    NASA Astrophysics Data System (ADS)

    Hieb, Jeffrey; Graham, James

    Distributed control systems (DCSs) play an essential role in the operation of critical infrastructures. Perimeter field devices are important DCS components that measure physical process parameters and perform control actions. Modern field devices are vulnerable to cyber attacks due to their increased adoption of commodity technologies and that fact that control networks are no longer isolated. This paper describes an approach for creating security-hardened field devices using operating system microkernels that isolate vital field device operations from untrusted network-accessible applications. The approach, which is influenced by the MILS and Nizza architectures, is implemented in a prototype field device. Whereas, previous microkernel-based implementations have been plagued by poor inter-process communication (IPC) performance, the prototype exhibits an average IPC overhead for protected device calls of 64.59 ?s. The overall performance of field devices is influenced by several factors; nevertheless, the observed IPC overhead is low enough to encourage the continued development of the prototype.

  11. [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

  12. Radial cold trap

    DOEpatents

    Grundy, B.R.

    1981-09-29

    The radial cold trap comprises a housing having a plurality of mesh bands disposed therein. The mesh bands comprise concentrically arranged bands of mesh with the mesh specific surface area of each band increasing from the outermost mesh band to the innermost mesh band. An inlet nozzle is attached to the outside section of the housing while an outlet nozzle is attached to the inner portion of the housing so as to be concentrically connected to the innermost mesh band. An inlet baffle having orifices therein may be disposed around the outermost mesh band and within the housing for directing the flow of the fluid from the inlet nozzle to the outermost mesh band in a uniform manner. The flow of fluid passes through each consecutive mesh band and into the outlet nozzle. The circular pattern of the symmetrically arranged mesh packing allows for better utilization of the entire cold trap volume. 2 figs.

  13. Cold cathodes for CFAs

    Microsoft Academic Search

    K. F. Ramacher; M. S. Worthington; G. R. MacPhail

    2000-01-01

    Summary form only given. Application of cold cathode technology for use in crossed-field amplifiers (CFAs) has been limited by the characteristics of the materials, usually platinum (Pt) or beryllium (Be\\/BeO), used as the emitter. A case in point is the L-4717, used as the second stage amplifier (baby Amplitron) in the SPS-48-C\\/E transmitters. This tube, which uses a thermionic emitter,

  14. Cold nuclear fusion

    SciTech Connect

    Tsyganov, E. N., E-mail: edward.tsyganov@utsouthwestern.edu [University of Texas Southwestern Medical Center at Dallas (United States)

    2012-02-15

    Recent accelerator experiments on fusion of various elements have clearly demonstrated that the effective cross-sections of these reactions depend on what material the target particle is placed in. In these experiments, there was a significant increase in the probability of interaction when target nuclei are imbedded in a conducting crystal or are a part of it. These experiments open a new perspective on the problem of so-called cold nuclear fusion.

  15. Crazy Cold Air

    NSDL National Science Digital Library

    In this classroom activity, students record the temperatures in and around a walk-in refrigerator or freezer to see how cold air behaves when it meets warmer air. The printable five-page handout includes a series of inquiry-based questions to get students thinking about how the temperature of air changes its density, detailed experiment directions and a worksheet that helps students use the experiment results to obtain insight into the wind patterns of Antarctica.

  16. Clumpy cold dark matter

    NASA Technical Reports Server (NTRS)

    Silk, Joseph; Stebbins, Albert

    1993-01-01

    A study is conducted of cold dark matter (CDM) models in which clumpiness will inhere, using cosmic strings and textures suited to galaxy formation. CDM clumps of 10 million solar mass/cu pc density are generated at about z(eq) redshift, with a sizable fraction surviving. Observable implications encompass dark matter cores in globular clusters and in galactic nuclei. Results from terrestrial dark matter detection experiments may be affected by clumpiness in the Galactic halo.

  17. The long day leaf as a source of cold hardiness inhibitors.

    PubMed

    Mac Irving, R; Lanphear, F O

    1967-10-01

    Short photoperiods followed by low temperatures induced cold hardiness in Acer negundo, Viburnum plicatum tomentosum, and Weigela florida. Hardiness was also obtained under long days and natural fall temperatures if the leaves were removed, either manually or by low temperature. Similarly, removal of leaves from plants exposed to long days at 5 degrees brought about an accelerated rate of hardening. These observations suggested the presence of a hardiness inhibitor in the leaves which was counteracted by short days or removal of the leaves. PMID:16656666

  18. Strain Hardening and Long-Range Internal Stress in the Localized Deformation of Irradiated Polycrystalline Metals

    SciTech Connect

    Byun, Thak Sang [ORNL; Hashimoto, Naoyuki [ORNL

    2006-01-01

    Low-temperature irradiation can significantly harden metallic materials and often results in microscopic strain localization such as dislocation channeling during deformation. In true stress-true strain analyses, however, the strain localization does not significantly affect macroscopic strain-hardening behavior. It was attempted to explain the strain-hardening behavior during strain localization in terms of long-range back stresses. In theoretical modeling the long-range back stress was formulated as a function of the number of residual pileup dislocations at a grain boundary and the number of localized bands formed in a grain. The strain-hardening rates in channel deformation were calculated for ten face-centered cubic (fcc) and body-centered cubic (bcc) metals. A few residual dislocations in each channel could account for the strain-hardening rates as high as those for uniform deformation. It was also shown that the strain-hardening behavior predicted by the long-range back stress model resembled the empirical strain-hardening behaviors, which result from both localized and non-localized deformations. The predicted plastic instability stress was comparable to the tensile test data.

  19. Progress in the technology and applications of in-situ atmosphere production in hardening and case-hardening furnaces

    SciTech Connect

    Edenhofer, B. [Ipsen Industries International GmbH, Kleve (Germany)

    1995-12-31

    The utilization of in-situ atmospheres for neutral hardening and gas carburizing is steadily increasing in batch furnaces as well as continuous furnaces. Depending on furnace temperature and type of fuel used for atmosphere production, the furnace atmosphere is closer to or further away from chemical equilibrium. This makes the carbon-potential measurement and control difficult. The theory of controllability of non-equilibrium atmospheres is shortly described. Different fuels possess different properties with respect to carbon transfer, case-structure (internal oxidation) and cycle speed. This is compared to other atmosphere systems like endothermic atmosphere and nitrogen/methanol based systems. The applicational range of different in-situ atmospheres varies. Its utilization in different furnaces is presented together with the achieved energy savings.

  20. 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

  1. Evolution of radiation defect and radiation hardening in heat treated SA508 Gr3 steel

    NASA Astrophysics Data System (ADS)

    Jin, Hyung-Ha; Kwon, Junhyun; Shin, Chansun

    2014-01-01

    The formation of radiation defects and corresponding radiation hardening in heat-treated SA508 Gr3 steel after Fe ion irradiation were investigated by means of transmission electron microscopy and a nano-indentation technique. As the residual dislocation density is increased in the matrix, the formation of radiation defects is considerably weakened. Comparison between the characteristics of the radiation defect and an evaluation of radiation hardening indicates that a large dislocation loop contributes little to the radiation hardening in the heat-treated SA508 Gr3 steel.

  2. COLD FLOWS AND THE FIRST QUASARS

    SciTech Connect

    Di Matteo, T.; Khandai, N.; DeGraf, C.; Feng, Y.; Croft, R. A. C. [McWilliams Center for Cosmology, Carnegie Mellon University, 5000 Forbes Avenue, Pittsburgh, PA 15213 (United States); Lopez, J. [Computer Science Department, Carnegie Mellon University, 5000 Forbes Avenue, Pittsburgh, PA 15213 (United States); Springel, V. [Heidelberg Institute for Theoretical Studies Schloss-Wolfsbrunnenweg 35, 68118 Heidelberg (Germany)

    2012-02-15

    Observations of the most distant bright quasars imply that billion solar mass supermassive black holes (SMBHs) have to be assembled within the first 800 million years. Under our standard galaxy formation scenario such fast growth implies large gas densities providing sustained accretion at critical or supercritical rates onto an initial black hole seed. It has been a long standing question whether and how such high black hole accretion rates can be achieved and sustained at the centers of early galaxies. Here we use our new MassiveBlack cosmological hydrodynamic simulation covering a volume (0.75 Gpc){sup 3} appropriate for studying the rare first quasars to show that steady high density cold gas flows responsible for assembling the first galaxies produce the high gas densities that lead to sustained critical accretion rates and hence rapid growth commensurate with the existence of {approx}10{sup 9} M{sub Sun} black holes as early as z {approx} 7. We find that under these conditions quasar feedback is not effective at stopping the cold gas from penetrating the central regions and hence cannot quench the accretion until the host galaxy reaches M{sub halo} > or approx. 10{sup 1}2{sup M}{sub Sun }. This cold-flow-driven scenario for the formation of quasars implies that they should be ubiquitous in galaxies in the early universe and that major (proto)galaxy mergers are not a requirement for efficient fuel supply and growth, particularly for the earliest SMBHs.

  3. Rapid Evaporation of microbubbles

    NASA Astrophysics Data System (ADS)

    Gautam, Jitendra; Esmaeeli, Asghar

    2008-11-01

    When a liquid is heated to a temperature far above its boiling point, it evaporates abruptly. Boiling of liquid at high temperatures can be explosive and destructive, and poses a potential hazard for a host of industrial processes. Explosive boiling may occur if a cold and volatile liquid is brought into contact with a hot and non-volatile liquid, or if a liquid is superheated or depressurized rapidly. Such possibilities are realized, for example, in the depressurization of low boiling point liquefied natural gas (LNG) in the pipelines or storage tanks as a result of a leak. While boiling of highly heated liquids can be destructive at macroscale, the (nearly) instantaneous pace of the process and the release of large amount of kinetic energy make the phenomena extremely attractive at microscale where it is possible to utilize the released energy to derive micromechanical systems. For instance, there is currently a growing interest in micro-explosion of liquid for generation of micro bubbles for actuation purposes. The aim of the current study is to gain a fundamental understanding of the subject using direct numerical simulations. In particular, we seek to investigate the boundary between stable and unstable nucleus growth in terms of the degree of liquid superheat and to compare the dynamics of unstable and stable growth.

  4. Influence of grain structure and solute composition on the work hardening behavior of aluminium at cryogenic temperatures

    SciTech Connect

    Chu, D.; Morris, J.W. Jr.

    1993-07-01

    An unrecrystallized structure is found to significantly improve the work hardening characteristics by lowering the work hardening rate during early stages of deformation. This is in contrast to a recrystallized structure, which requires a higher work hardening rate to accommodate the greater degree of multiple slip necessary to maintain strain compatibility between the more randomly oriented grains. The stronger texture associated with the unrecrystallized structure allows deformation to occur more efficiently. Addition of magnesium also improves work hardening by increasing overall level of the work hardening rate. The improved characteristics of the work hardening behavior result in a parallel increase in both the strength and ductility at cryogenic temperatures. These findings are positive since they suggest a method by which improvements in the work hardening behavior and subsequent mechanical properties may be obtained through practical modifications of the microstructure and composition.

  5. Cold Drawn Steel Wires-Processing, Residual Stresses and Ductility-Part I: Metallography and Finite Element Analyses

    SciTech Connect

    Phelippeau,A.; Pommier, S.; Tsakalakos, T.; Clavel, M.; Prioul, C.

    2006-01-01

    Cold drawing steel wires lead to an increase of their mechanical strength and to a drop of their ductility. The increase of their mechanical strength has long been related to the reduction of the various material scales by plastic deformation, but the mechanisms controlling their elongation to failure have received relatively little attention. It is usually found that heavily deformed materials show a tendency to plastic strain localization and necking. However, in this paper it is shown that, though the steel wires are plastically deformed up to strain levels as high as 3.5, a significant capability of plastic deformation is preserved in as-drawn wires. This apparent contradiction is resolved by the existence of residual stresses inside the wire. Finite element analyses have been conducted in order to show that residual stresses, inherited from the drawing process, are sufficient to produce a significant hardening effect during a post-drawing tensile test, without introducing any hardening in the local material behavior. The main conclusion of this paper is that once the material has lost its hardening capabilities, residual stresses, inherited from the process, control the elongation of cold drawn wires. The finite element method allowed also the determination of the residual stress field that would lead to the best agreement between the simulated and the experimental stress strain curve of as-drawn wires.

  6. Ultrathin SiOxNy by rapid thermal heating of silicon in N2 at T 7601050 C

    E-print Network

    Gustafsson, Torgny

    thermal processing chamber. Gas phase impurities such as H2O, O2, and H2, which can outgas from the cold2, and O2, the growth chamber, a cold wall rapid thermal processing RTP module, contributesUltrathin SiOxNy by rapid thermal heating of silicon in N2 at T 760­1050 °C M. L. Green and T

  7. Conformal Plasma Cathode for Surface Hardening of Steels

    NASA Astrophysics Data System (ADS)

    Liu, Shengyi

    1995-01-01

    Surface hardening of steels by electron beams, of energy ~MeV and current density ~kA/cm^2, from a conformal plasma cathode inherently has many advantages, such as uniform treatment, simple-system configuration, efficient energy transfer and relatively-low cost, over conventional electron beam hardening systems. Exploitation of these advantages relies on generation of an anode sheath, adjacent to the workpiece surface, that has a majority of the diode voltage drop. Electrons accelerated by the strong anode sheath field are normally incident on the workpiece surface, so that a significant heating depth and uniform and high hardness can be achieved without risk of melting the surface. For the purpose of forming such an electron beam, the characteristics of plasma sheaths have been extensively studied to discover the relationship between the cathode and the anode sheath, and to reveal the conditions to create such a dominant anode sheath. To obtain a dominant anode sheath, intense cathode emission is a necessity for a diode of planar geometry, and an area ratio of the cathode surface to the anode surface at least 10 is required for a diode of non-planar geometry. In both approaches, the anode sheath current is increased to a level that is larger than the electron thermal convection current. The current increase in the first case is due to the effects of charge neutralization and mass reduction caused by cathode emission in the cathode sheath region. The same result is obtained in the second case because of an area ratio effect. A dominant anode sheath is ensured if both approaches are considered in the design of a conformal plasma cathode. A plasma cathode that conforms well to the workpiece surface geometry requires an anode sheath thickness of only a few mm. A beam current pulse of ~100 ns duration produced under the above -described conditions will heat the entire surface, at a rate of 10^7~10^9^ circC/s to cause a fast austenitizing process over a considerable depth (~1 mm). The temperature at the surface, however, remains below the melting point. Energy loss due to ion acceleration in this system is less than 5%.

  8. 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 scans with an adequate framework performed on a daily basis reduce the amount of security work load as well as the timeliness in performing remediation, as verified by the NINJA framework. A vulnerability assessment/auditing architecture based on mobile agent technology is proposed and examined at the end of the article as an enhancement to the current NINJA architecture.

  9. Strain hardening and plasticity of low-carbon steels with a heterophase structure: I. Strain hardening characteristics of steels during uniaxial tension

    NASA Astrophysics Data System (ADS)

    Shveikin, V. P.; Smirnov, S. V.

    2009-10-01

    The strain hardening characteristics of low-carbon 10kp, 05G2S2, and 05G2R steels with a heterophase structure (ferritic-martensitic, ferritic-bainitic, ferritic-pearlitic) formed upon quenching from the intercritical temperature range and upon normalization are studied during uniaxial tension. The dislocation structures of these steels are examined by electron microscopy and internal friction, and the results obtained are used to explain the factors that cause the high strain-hardening rate of steels with a two-phase ferritic-martensitic structure. Stress-strain diagrams are constructed for steel samples that have various heterophase structures and are subjected to a small preliminary deformation (up to 10%); these diagrams can be used to compare the strain-hardening characteristics of the steels.

  10. Peregrinations on cold fusion

    SciTech Connect

    Turner, L.

    1989-01-01

    Attention is focused on the possibility of resonance-enhanced deuteron Coulomb barrier penetration. Because of the many-body nature of the interactions of room-temperature deuterons diffusing through a lattice possessing deuterons in many of the interstitial positions, the diffusing deuterons can resonate on the atomic scale in the potential wells bounded by the ascending walls of adjacent Coulomb barriers and thereby penetrate the Coulomb barriers in a fashion vastly underestimated by two-body calculations in which wells for possible resonance are absent. Indeed, perhaps the lack of robust reproducibility in cold fusion originates from the narrowness of such transmission resonances. 4 refs., 1 fig.

  11. The Isis cold moderators

    SciTech Connect

    Allen, G. M.; Broome, T. A.; Burridge, R. A.; Cragg, D.; Hall, R.; Haynes, D.; Hirst, J.; Hogston, J. R.; Jones, H. H.; Sexton, J.; Wright, P.

    1997-09-01

    ISIS is a pulsed spallation neutron source where neutrons are produced by the interaction of a 160 kW proton beam of energy 800 MeV in a water-cooled Tantalum Target. The fast neutrons produced are thermalized in four moderators: two ambient water, one liquid methane operating at 100K and a liquid hydrogen moderator at 20 K. This paper gives a description of the construction of both cold moderator systems, details of the operating experience and a description of the current development program.

  12. Hot and Cold

    NSDL National Science Digital Library

    Oregon Museum of Science and Industry

    1997-01-01

    In this activity, learners explore temperature changes from chemical reactions by mixing urea with water in one flask and mixing calcium chloride with water in another flask. They observe that the urea flask gets cold and the calcium chloride flask gets hot. The main idea is that some chemical processes release heat energy and are exothermic, while some chemical processes absorb heat energy and are endothermic. This activity is currently used in the Nature of Matter Unit in OMSI's Chemistry Lab. Cost estimates are per 100 learners.

  13. Endochronic theory, non-linear kinematic hardening rule and generalized plasticity: a

    E-print Network

    Paris-Sud XI, Université de

    models of Prandtl- Reuss and Prager (see e.g. Lemaitre and Chaboche (1990)) and the NLK hardening model by Chaboche (1991) and Ohno and Wang (1993) in order to improve the ratchetting modelling. For these models

  14. Hardening of the surface layers of a hollow billet formed by centrifugal casting

    NASA Astrophysics Data System (ADS)

    Chumanov, V. I.; Chumanov, I. V.; Anikeev, A. N.; Garifulin, R. R.

    2010-12-01

    One of the methods to increase the mechanical properties of steel is its hardening via the introduction of a refractory fine-grained phase into a melt. A method of fabrication of a tube blank by centrifugal casting accompanied by hardening with a refractory phase is considered. The introduction of fine tungsten and silicon carbides is shown to improve the structure of grade 15 steel and to increase the wear resistance of a tube blank made of this steel.

  15. Thermal decomposition of fire retardant brominated epoxy resins cured with different nitrogen containing hardeners

    Microsoft Academic Search

    M. P. Luda; A. I. Balabanovich; M. Zanetti; D. Guaratto

    2007-01-01

    Epoxy resins frequently have to meet a flame retardancy grade which can be accomplished by incorporating brominated reactive compounds, like tetrabromobisphenol A (TBBA) cured by a number of hardeners. A few brominated epoxy resins (BERs) have been prepared by curing a mixture of diglycidyl ethers of bisphenol A (DGEBA)\\/diglycidyl ethers of tertabromobisphenol A (DGETBBA) and different hardeners: dicyandiamide (DICY), 4,4?-diaminodiphenyl

  16. Hardening of Fe-Cu alloys at elevated temperatures by electron and neutron irradiations

    NASA Astrophysics Data System (ADS)

    Tobita, T.; Suzuki, M.; Iwase, A.; Aizawa, K.

    2001-12-01

    Comparative experiments using 2.5 MeV electron irradiations to Fe-Cu model alloys have been undertaken to study the gamma-ray induced hardening of RPV steels. Hardness changes induced by Cu precipitates for Fe-0.6%CU model alloy was confirmed. The difference between electron and neutron irradiation hardening was very small on a dpa basis except for very low dpa.

  17. Ramberg-Osgood strain-hardening characterization on an ASTM A302B steel

    Microsoft Academic Search

    L. A. James

    1995-01-01

    Many elastic-plastic fracture mechanisms analysis procedures require knowledge of the true stress versus true strain response of the material being analyzed. The most common strain-hardening relationship employed is of the form first proposed by Ramberg and Osgood. Here, the Ramberg-Osgood strain-hardening exponents and coefficients are characterized for an unirradiated ASTM A302-B steel over a wide range of temperatures from -129

  18. Converting a bulk radiation-hardened BiCMOS technology into a dielectrically-isolated process

    Microsoft Academic Search

    M. Delaus; D. Emily; B. Mappes; R. Pease

    1993-01-01

    A radiation-hardened dielectrically isolated BiCMOS process has been developed by retrofitting dielectric isolation to an existing radiation-hardened JI (junction-isolated) process. The process is fabricated on a bonded-wafer silicon-on-insulator (SOI) substrate and employs deep trenches for lateral device isolation. The isolation technique employed is similar to that used on advanced commercial complementary-bipolar processes. Trench\\/substrate induced defects are sensitive to the device

  19. Effect of magnetic field on the amount of retained austenite in hardened steels

    Microsoft Academic Search

    Yu. V. Kaletina; E. A. Fokina

    2008-01-01

    Results of studies of the effect of a pulse magnetic field on the amount of retained austenite in hardened steels of various\\u000a chemical compositions are reviewed. High-intensity magnetic field causes additional formation of martensite, which can increase\\u000a the hardness and the stability of sizes of parts. Treatment of hardened steels in magnetic field in addition to the effects\\u000a obtained by

  20. Synthesis of a new hardener agent for self-healing epoxy resins

    NASA Astrophysics Data System (ADS)

    Raimondo, Marialuigia; Guadagno, Liberata; Naddeo, Carlo; Longo, Pasquale; Mariconda, Annaluisa; Agovino, Anna

    2014-05-01

    Actually, the development of smart composites capable of self-repair in aeronautical structures is still at the planning stage owing to complex issues to overcome. One of the critical points in the development of self-healing epoxy resin is related to the impossibility to employ primary amines as hardeners. In this paper, the synthesis of a new hardener for self-healing resins is shown together with applicability conditions/ranges.

  1. Sheet metal forming simulation using finite elastoplasticity with mixed isotropic\\/kinematic hardening

    Microsoft Academic Search

    Sami Chatti; Narjess Chtioui

    2011-01-01

    A numerical formulation is presented for anisotropic elastoplasticity behavior in finite strain with non-linear isotropic\\/kinematic hardening model. Non-linear kinematic hardening is modeled by the Lemaitre-Chaboche law with the aim of considering cyclic deformation phenomena. User-defined material subroutines are developed based on Hill’s quadratic yield function for both ABAQUS-Explicit (VUMAT) and ABAQUS-Standard (UMAT). For validation purpose, the tension-compression and cyclic shear

  2. Hardening of welded joints in titanium alloys, produced by electron-beam welding

    Microsoft Academic Search

    M. A. Khorev

    1985-01-01

    The ultimate strength of welded joints in alloys VT6S, VT14, VT23, and VT19 is 1100, 1150, 1300, and 1250 MPa, and the effectiveness of hardening, ?su=200, 250, 300, and 250, respectively, as a result of hardening heat treatment — quenching from the temperature of the upper boundary of the (a+ß)-region and subsequent aging at 450–560°C.

  3. Influence of shot peening on bending tooth fatigue limit of case hardened gears

    Microsoft Academic Search

    M. Benedetti; V. Fontanari; B.-R. Höhn; P. Oster; T. Tobie

    2002-01-01

    The effect of different surface treatments on the fatigue behaviour at the tooth root of spur gears is investigated. Case hardening and case hardening followed by shot peening were considered for 16MnCr5 steel gears. Pulsating tests (R=0.1) were carried out on gear teeth to determine the fatigue endurance at 6×106 cycles. Residual stress profiles were measured at the tooth root

  4. The influence of different conditions of laser-beam interaction in laser surface hardening of steels

    Microsoft Academic Search

    J. Grum; T Kek

    2004-01-01

    The paper presents the results of laser-beam interaction in laser surface hardening of C45E steel with different types of absorbing coating on specimen surfaces. A photodiode was used to capture IR radiation from the interaction spot between a laser beam and a specimen surface having different absorbing coatings. The influence of laser-hardening parameters, type of absorber and absorbing coating thickness

  5. Occupational Dermatoses from One-Component Epoxy Coatings Containing a Modified Polyamine Hardener

    Microsoft Academic Search

    Kozo YOKOTA; Yasushi JOHYAMA; Kyohei YAMAGUCHI

    2000-01-01

    In an electronics plant, 2 one-component epoxy coatings containing a modified polyamine hardener were used as covering materials for protecting important information on police radio circuit boards. The resinous parts of the coatings consisted of epoxy resins based on diglycidyl ether of bisphenol F. The hardener was a dimethylaminopropylamine (DMAPA)-epoxy adduct and contained about 0.16% free DMAPA. Of 105 workers,

  6. Simulation and experimental verification of induction hardening process for some kinds of steel

    SciTech Connect

    Inoue, T.; Inout, H.; Uehara, T. [Kyoto Univ. (Japan)] [and others

    1996-12-31

    Structure evolution and stress/distortion by induction hardening process of stationary type are simulated for ring shaped specimen made of several kinds of steel. Applicability of the method of simulation is evaluated by comparing the results of calculation on stress and distortion with the experiments for steels with and without hardenability and also for different geometry. Detail discussions on the distribution of residual stresses and the mode of distortion are made in relation to the material properties.

  7. A comparison of current work-hardening models used in the analysis of plastic deformations 

    E-print Network

    Vaughn, David Kenneth

    1973-01-01

    A COMPARISON OF CURRENT WORK-HARDENING MODELS USED IN THE ANALYSIS OF PLASTIC DEFORMATIONS A Thesis by DAVID KENNETH VAUGHAN Submitted to the Graduate College of Texas A&M University in partial fulfillment of the requirement for the degree... of Committee) ( ead of Department) (Member) ( ber) December 1973 ABSTRACT A Comparison of Current Work-Hardening Models Used in the Analysis of Plastic Deformations. (December 1973) David Kenneth Vaughan, B. S. , Texas A&M University Directed by: Dr. J...

  8. 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

  9. 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.

  10. The structural dependence of work hardening in low carbon steels

    SciTech Connect

    Johnson, P.E.

    1991-12-01

    The influence of the dislocation cell structure on the work hardening behavior of low carbon steel sheets was investigated. Specimens were prestrained at low temperature to suppress cell formation and their subsequent behavior was compared with results of isothermal reference tests. It was found that the extent of cell development has little or no influence on the plastic behavior at room temperature and below. Interrupted temperature, tensile-shear tests demonstrated further that the transient behavior induced by loading path changes is also not strongly associated with the cell walls. In-situ straining studies indicate that the factor controlling the flow stress at room temperature is the limited mobility of screw dislocations moving the cell interiors, and not dislocation interactions with the cell walls. The unique properties of a/2<111> screw dislocations are known to dominate low temperature deformation behavior in bcc metals. The current work indicates that these dislocations may still control the flow stress at intermediate temperatures, even in the presence of a developed cell structure.

  11. 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

  12. 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.

  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. Roller Burnishing - A Cold Working Tool to Reduce Weld Induced Residual Stress

    SciTech Connect

    John Martin

    2002-02-19

    The possibility of stress corrosion cracking (SCC) in regions of tensile residual stress introduced by weld deposited material has been a concern where environmental effects can reduce component life. Roller burnishing, a form of mechanical cold-working, has been considered as a means of providing for residual stress state improvements. This paper provides a computational evaluation of the roller burnishing process to address the permanent deformation needed to introduce a desirable residual stress state. The analysis uses a series of incrementally applied pressure loadings and finite element methodology to simulate the behavior of a roller burnishing tool. Various magnitudes of applied pressure loadings coupled with different size plates and boundary conditions are examined to assess the degree and depth of the residual compressive stress state after cold working. Both kinematic and isotropic hardening laws are evaluated.

  15. Control of ion transport by mitochondrion-rich chloride cells of eurythermic teleost fish: Cold shock vs. cold acclimation.

    PubMed

    Buhariwalla, H E C; Osmond, E M; Barnes, K R; Cozzi, R R F; Robertson, G N; Marshall, W S

    2012-07-01

    Seawater-acclimated eurythermic mummichogs (Fundulus heteroclitus L.) were acclimated to cold and warm conditions (5 and 20 °C, 4 weeks). Opercular epithelia (OE) from 20 °C-acclimated animals, containing numerous mitochondrion-rich chloride cells were mounted in Ussing-style membrane chambers, cooled to 16, 13, 10, 5 and 2.5 °C, then subjected to hypotonic shock that normally inhibits Cl(-) secretion (as short-circuit current, I(sc)). Cold exposure to 10 °C slowed Cl(-) secretion (Q(10)=1.62 ± 0.204 95% CI) and OEs responded rapidly and reversibly to hypotonic shock, but below 8.0 °C a sharp decrease (Q(10)=5.63 ± 0.736) occurred and the tissue was unresponsive to hypotonicity. By immunocytochemistry, Focal Adhesion Kinase (FAK) phosphorylated at tyrosine-407 (pY(407)) colocalized with CFTR in apical membrane and dephosphorylated with hypotonic shock at 20 °C but failed to dephosphorylate at 5 °C, while opercular epithelia from cold-acclimated fish at 5 and 20 °C responded normally to hypotonic shock. Cold-shock of warm-acclimated OEs also stimulated covering over of mitochondrion- rich cell apical crypts, detected by SEM. Cold-acclimation increased C18:1 and decreased C18:0 fatty acids in liver, indicating homeoviscous adaptation. Eurythermic fish acclimate osmoregulatory systems to cold by maintaining membrane fluidity and preserving complex transport regulation pathways. PMID:22465000

  16. Deformation and strain hardening of different steels in impact dominated systems

    SciTech Connect

    Rojacz, H., E-mail: rojacz@ac2t.at [AC"2T research GmbH, Viktor-Kaplan-Straße 2, 2700 Wiener Neustadt (Austria); Mozdzen, G. [Aerospace and Advanced Composites GmbH, Viktor-Kaplan-Straße 2, 2700 Wiener Neustadt (Austria); Winkelmann, H. [AC"2T research GmbH, Viktor-Kaplan-Straße 2, 2700 Wiener Neustadt (Austria)

    2014-04-01

    Strain hardening is a common technique to exploit the full potential of materials in diverse applications. Single impact studies were performed to evaluate work hardening effects of different steels, correlated to their deformation at different energy and momentum levels. Three different steels were examined regarding their forming behavior and their tendency to strain harden in impact loading conditions, revealing different intensities of hardness increase, deformation and coinciding microstructural changes. Detailed studies in the deformed zone such as micro hardness mappings were performed to reveal the materials hardness increase in the deformed zones. Additionally high resolution scanning electron microscopy (HRSEM) supported by electron backscatter diffraction (EBSD) was used to determine microstructural changes. Results indicate, that the influence of different velocities/strain rates at constant energy levels cannot be neglected for the strain hardening behavior of steels and provide data for a better control of the hardness increase in impact dominated materials fabrication operations. - Highlights: • Deformation and strain hardening behaviour of three different steels. • Influence of impact energies and momenta on the strain hardening. • Hardness increase and depth controllable by momentum and energy.

  17. Study on the Influence of the Work Hardening Models Constitutive Parameters Identification in the Springback Prediction

    SciTech Connect

    Oliveira, M.C.; Menezes, L. F. [CEMUC, Department of Mechanical Engineering, University of Coimbra, Polo II, 3030 Coimbra (Portugal); Alves, J.L. [Department of Mechanical Engineering, University of Minho, Campus de Azurem, 4800-058 Guimaraes (Portugal); Chaparro, B.M. [Polythecnic Institute of Tomar, Rua 17 de Agosto de 1808, 2200-273 Abrantes (Portugal)

    2005-08-05

    The main goal of this work is to determine the influence of the work hardening model in the numerical prediction of springback. This study will be performed according with the specifications of the first phase of the 'Benchmark 3' of the Numisheet'2005 Conference: the 'Channel Draw'. Several work hardening constitutive models are used in order to allow a better description of the different material mechanical behavior. Two are classical pure isotropic hardening models described by a power law (Swift) or a Voce type saturation equation. Those two models were also combined with a non-linear (Lemaitre and Chaboche) kinematic hardening rule. The final one is the Teodosiu microstructural hardening model. The study is performed for two commonly used steels of the automotive industry: mild (DC06) and dual phase (DP600) steels. The mechanical characterization, as well as the constitutive parameters identification of each work hardening models, was performed by LPMTM, based on an appropriate set of experimental data such as uniaxial tensile tests, monotonic and Bauschinger simple shear tests and orthogonal strain path tests, all at various orientations with respect to the rolling direction. All the simulations were carried out with the CEMUC's home code DD3IMP (contraction of 'Deep Drawing 3-D IMPlicit code')

  18. Study on the Influence of the Work Hardening Models Constitutive Parameters Identification in the Springback Prediction

    NASA Astrophysics Data System (ADS)

    Oliveira, M. C.; Alves, J. L.; Chaparro, B. M.; Menezes, L. F.

    2005-08-01

    The main goal of this work is to determine the influence of the work hardening model in the numerical prediction of springback. This study will be performed according with the specifications of the first phase of the "Benchmark 3" of the Numisheet'2005 Conference: the "Channel Draw". Several work hardening constitutive models are used in order to allow a better description of the different material mechanical behavior. Two are classical pure isotropic hardening models described by a power law (Swift) or a Voce type saturation equation. Those two models were also combined with a non-linear (Lemaître and Chaboche) kinematic hardening rule. The final one is the Teodosiu microstructural hardening model. The study is performed for two commonly used steels of the automotive industry: mild (DC06) and dual phase (DP600) steels. The mechanical characterization, as well as the constitutive parameters identification of each work hardening models, was performed by LPMTM, based on an appropriate set of experimental data such as uniaxial tensile tests, monotonic and Bauschinger simple shear tests and orthogonal strain path tests, all at various orientations with respect to the rolling direction. All the simulations were carried out with the CEMUC's home code DD3IMP (contraction of `Deep Drawing 3-D IMPlicit code').

  19. Responses of cutaneous A-fiber nociceptors to noxious cold.

    PubMed

    Simone, D A; Kajander, K C

    1997-04-01

    Responses of cutaneous nociceptors to natural stimuli, particularly mechanical and heat stimuli, have been well documented. Although nociceptors are excited by noxious cold stimuli, there have been few studies of their stimulus-response functions for cold stimuli over a wide range of stimulus temperatures. Furthermore, the proportion of nociceptors excited by noxious cold is not clear. In the present study, we examined responses of mechanosensitive A delta-nociceptors and low-threshold mechanoreceptors to a wide range of cold stimuli that included stimulus temperatures <0 degrees C. Electrophysiological recordings were made from single primary afferent fibers in the saphenous nerves of anesthetized rats. Cutaneous sensory receptors were classed according to their conduction velocity and subgrouped functionally according to their responses evoked by mechanical, heat, and cold stimuli (0 degrees C). Responses evoked by a wide range of cold stimulus intensities that included stimuli considered innocuous and noxious (painful) were then assessed. Stimuli of 20 to -20 degrees C were delivered to the receptive field via a 1-cm2 contact thermode from a base temperature of 32 degrees C. Stimuli were applied in descending order of 2 degrees C decrements. Stimulus ramp rate was 5 degrees C/s, and stimulus temperatures were applied for a duration of 10 s. A total of 90 A fibers was studied, of which 61 were nociceptors and had conduction velocity in the A delta-range (2-30 m/s). Nociceptors were classed initially as mechanical, mechanoheat, and mechanocold nociceptors. The remaining 29 fibers were low-threshold mechanoreceptors with conduction velocity in the A delta- or A beta-range (>30 m/s). These were subgrouped according to their adaptive properties as slowly or rapidly adapting, and according to whether they were excited by hair movement (hair follicle afferent fibers). All nociceptors were excited by noxious cold. Only 30% of nociceptors were considered sensitive to cold on initial classification with the use of a cold stimulus of 0 degrees C. However, all nociceptors were excited by stimulus intensities <0 degreesC. Response thresholds for cold ranged from 14 to -18 degrees C (-4.6 +/- 1.07 degrees C, mean +/- SE). The total number of impulses, discharge rate, and peak discharge increased monotonically as intensity of cold stimuli increased. Power functions were used to determine the rate at which the number of impulses increased as stimulus intensity increased. The slopes of power funcions ranged from 0.12 to 2.28 (mean 1.07 +/- 0.13). Most mechanoreceptors were not excited by cold stimuli. The only types of mechanoreceptors that responded reliably to cold stimuli were the slowly adapting mechanoreceptors. Responses usually occurred during the temperature ramp when the skin temperature was decreasing. There was no evidence that mechanoreceptors encoded the intensity of cold stimuli at intensities above or below 0 degrees C, because evoked responses did not increase with intensity of cold stimuli. It is concluded that the proportion of cutaneous A delta-nociceptors excited by noxious cold stimuli has been underestimated in previous studies. All nociceptors were excited by stimulus temperatures <0 degrees C and encoded the intensity of cold stimuli. It is therefore likely that cutaneous A delta-nociceptors contribute to the sensation of cold pain, particularly pain produced by stimulus temperatures <0 degrees C. PMID:9114254

  20. Effect of nitrogen and cold working on structural and mechanical behavior of Ni-free nitrogen containing austenitic stainless steels for biomedical applications.

    PubMed

    Talha, Mohd; Behera, C K; Sinha, O P

    2015-02-01

    This investigation deals with the evaluation of structural and mechanical behavior of deformed (10% and 20% cold work) and annealed (at 1050°C for 15 min followed by water quenching) Ni-free high nitrogen austenitic stainless steels (HNSs). The microstructure was observed by optical micrograph and the mechanical properties were determined by macrohardness and tensile tests. Both stress strain behavior and work hardening behavior were evaluated. HNSs have smaller grain size as compared to low nitrogen steels and no formation of martensite was observed after 20% cold working. Further, it was found that hardness; yield strength and ultimate tensile strength of the steels linearly increases and elongation decreased with nitrogen content and degree of cold working. The strength coefficient was observed to be higher for the high nitrogen steels; it decreased to some extent with degree of cold working. The work hardening exponent was also observed to decrease with degree of cold working. Influence of nitrogen on mechanical properties was mainly related to its effect on solid solution strengthening. X-ray diffraction analysis of annealed as well as deformed alloys further confirmed no evidence for formation of martensite or any other secondary phases. SEM fractography of the annealed and deformed samples after tensile tests indicates predominantly ductile fracture in all specimens. PMID:25492189

  1. Aerodynamics inside a rapid compression machine

    SciTech Connect

    Mittal, Gaurav; Sung, Chih-Jen [Department of Mechanical and Aerospace Engineering, Case Western Reserve University, Cleveland, OH 44106 (United States)

    2006-04-15

    The aerodynamics inside a rapid compression machine after the end of compression is investigated using planar laser-induced fluorescence (PLIF) of acetone. To study the effect of reaction chamber configuration on the resulting aerodynamics and temperature field, experiments are conducted and compared using a creviced piston and a flat piston under varying conditions. Results show that the flat piston design leads to significant mixing of the cold vortex with the hot core region, which causes alternate hot and cold regions inside the combustion chamber. At higher pressures, the effect of the vortex is reduced. The creviced piston head configuration is demonstrated to result in drastic reduction of the effect of the vortex. Experimental conditions are also simulated using the Star-CD computational fluid dynamics package. Computed results closely match with experimental observation. Numerical results indicate that with a flat piston design, gas velocity after compression is very high and the core region shrinks quickly due to rapid entrainment of cold gases. Whereas, for a creviced piston head design, gas velocity after compression is significantly lower and the core region remains unaffected for a long duration. As a consequence, for the flat piston, adiabatic core assumption can significantly overpredict the maximum temperature after the end of compression. For the creviced piston, the adiabatic core assumption is found to be valid even up to 100 ms after compression. This work therefore experimentally and numerically substantiates the importance of piston head design for achieving a homogeneous core region inside a rapid compression machine. (author)

  2. Investigation of Clusters in Medium Carbon Secondary Hardening Ultra-high-strength Steel After Hardening and Aging Treatments

    NASA Astrophysics Data System (ADS)

    Veerababu, R.; Balamuralikrishnan, R.; Muraleedharan, K.; Srinivas, M.

    2015-06-01

    Clusters, containing between 10 and 1000 atoms, have been investigated in a martensitic secondary hardening ultra-high-strength steel austenitized at 1173 K (900 °C) for 1 hour and tempered at either 768 K or 783 K (495 °C or 510 °C) for 4 or 8 hours using 3D atom probe. The presence of clusters was unambiguously established by comparing the observed spatial distribution of the different alloying elements against the corresponding distribution expected for a random solid solution. Maximum separation envelope method has been used for delineating the clusters from the surrounding "matrix." Statistical analysis was used extensively for size and composition analyses of the clusters. The clusters were found to constitute a significant fraction accounting for between 1.14 and 2.53 vol pct of the microstructure. On the average, the clusters in the 783 K (510 °C) tempered sample were coarser by ~65 pct, with an average diameter of 2.26 nm, relative to the other samples. In all samples, about 85 to 90 pct of the clusters have size less than 2 nm. The percentage frequency histograms for carbon content of the clusters in 768 K and 783 K (495 °C and 510 °C) tempered samples revealed that the distribution shifts toward higher carbon content when the tempering temperature is higher. It is likely that the presence of these clusters exerts considerable influence on the strength and fracture toughness of the steel.

  3. Structure and strain hardening of low stacking fault energy FCC alloys at large strains

    NASA Astrophysics Data System (ADS)

    Asgari, Sirous

    1997-11-01

    Structure and strain hardening of alpha-brass and two Co-Ni based superalloys, MP35N and AEREX350, were investigated. Constant true strain rate simple compression tests to large strains conducted on annealed, polycrystalline samples of alpha-brass, MP35N and AEREX350 alloys, revealed a four-stage hardening response in these materials, distinctly different from that observed in higher SFE fcc materials, such as copper. In each stage, microstructure was studied using optical microscopy and TEM. It was shown that deformation twinning played a decisive role in hardening response of the low SFE materials used in this study. At high strains, some localization in the form of grain-scale shear bands was observed. Although formation of these shear bands had no detectable effect on the macroscopic strain hardening rate, it did correlate with a marked change in texture evolution. Based on observations, a physical description of the microstructural phenomena responsible for the various strain hardening stages observed in low SFE fcc alloys is presented. A significant decrease in the hardening rate of ultra-fine MP35N alloy (1 mum grain size) was observed at moderate to high strains. TEM studies showed that this behavior correlated with the lack of extensive twinning in the structure, confirming the critical role of deformation twinning in hardening response of the alloy of larger grain size. Deformed MP35N alloy could be further strengthened by heat treating at 593sp°C for four hours. This secondary hardening phenomenon together with the high temperature hardening response of MP35N was investigated. A model based on segregation of solute atoms to stacking faults was proposed to account for the observations. TEM studies showed that the major strengthening phase in the solution treated and aged AEREX350 alloy was gammasp' (Nisb3Al,Ti) with L1sb2 structure. This phase was stable up to 1000sp°C and its growth kinetics followed the tsp{1/3} law. The work hardening rate of the aged AEREX350 alloy in simple compression significantly increased in moderate strains, compared to that of the solution treated alloy. This behavior may be related to the reduction of the stacking fault energy of the aged material caused by precipitation of the gammasp' phase.

  4. Cold Dark Matter Resuscitated?

    E-print Network

    Martin White; Douglas Scott; Joe Silk; Marc Davis

    1995-08-21

    The Cold Dark Matter (CDM) model has an elegant simplicitly which makes it very predictive, but when its parameters are fixed at their `canonical' values its predictions are in conflict with observational data. There is, however, much leeway in the initial conditions within the CDM framework. We advocate a re-examination of the CDM model, taking into account modest variation of parameters from their canonical values. We find that CDM models with $n=0.8$--0.9 and $h=0.45$--0.50 can fit the available data. Our ``best fit'' CDM model has $n=0.9$, $h=0.45$ and $C_2^{T}/C_2^{S}=0.7$. We discuss the current state of observations which could definitely rule out this model.

  5. Hot Planet - Cold Comfort

    NSDL National Science Digital Library

    This page features videos from the "Hot Planet- Cold Comfort" television episode, related website articles and a student activity. The videos explore how the Gulf Stream conveyor belt may shut down; how Arctic river runoff and Alaskan glacial melt are freshening the oceans; and how ocean sediments and ice cores are being studied to understand the Little Ice Age. The videos total approximately one hour in length. The website articles explore the Little Ice Age; how the Arctic functions as a global thermostat, affecting global weather patterns; and great moments in climate change. The student activity is about light absorbtion. The site also contains a challenge activity to find details in a painting that depict Little Ice Age living conditions.

  6. Monitoring the vaccine cold chain

    Microsoft Academic Search

    E Cheriyan

    1993-01-01

    Maintaining the vaccine cold chain is an essential part of a successful immunisation programme. A continuous electronic temperature monitor helped to identify breaks in the cold chain in the community and the study led to the issue of proper guidelines and replacement of faulty equipment.

  7. Encyclopedia of the Cold War

    Microsoft Academic Search

    Dijk van R

    2008-01-01

    Between 1945 and 1991, tension between the USA, its allies, and a group of nations led by the USSR, dominated world politics. This period was called the Cold War – a conflict that stopped short to a full-blown war. Benefiting from the recent research of newly open archives, the Encyclopedia of the Cold War discusses how this state of perpetual

  8. Tip model of cold fission

    Microsoft Academic Search

    F. Gönnenwein; B. Börsig

    1991-01-01

    Cold fission is defined to be the limiting case of nuclear fission where virtually all of the available energy is converted into the total kinetic energy of the fragments. The fragments have, therefore, to be born in or at least close to their respective ground states. Starting from the viewpoint that cold fission corresponds to most compact scission configurations, energy

  9. Setting reaction and hardening of an apatitic calcium phosphate cement.

    PubMed

    Ginebra, M P; Fernández, E; De Maeyer, E A; Verbeeck, R M; Boltong, M G; Ginebra, J; Driessens, F C; Planell, J A

    1997-04-01

    The combination of self-setting and biocompatibility makes calcium phosphate cements potentially useful materials for a variety of dental applications. The objective of this study was to investigate the setting and hardening mechanisms of a cement-type reaction leading to the formation of calcium-deficient hydroxyapatite at low temperature. Reactants used were alpha-tricalcium phosphate containing 17 wt% beta-tricalcium phosphate, and 2 wt% of precipitated hydroxyapatite as solid phase and an aqueous solution 2.5 wt% of disodium hydrogen phosphate as liquid phase. The transformation of the mixture was stopped at selected times by a freeze-drying techniques, so that the cement properties at various stages could be studied by means of x-ray diffraction, infrared spectroscopy, and scanning electron microscopy. Also, the compressive strength of the cement was measured as a function of time. The results showed that: (1) the cement setting was the result of the alpha-tricalcium phosphate hydrolysis, giving as a product calcium-deficient hydroxyapatite, while beta-tricalcium phosphate did not participate in the reaction; (2) the extent of conversion of alpha-TCP was nearly 80% after 24 hr; (3) both the extent of conversion and the compressive strength increased initially linearly with time, subsequently reaching a saturation level, with a strong correlation observed between them, indicating that the microstructural changes taking place as the setting reaction proceeded were responsible for the mechanical behavior of the cement; and (4) the microstructure of the set cement consisted of clusters of big plates with radial or parallel orientations in a matrix of small plate-like crystals. PMID:9126187

  10. On the work hardening of fiber reinforced copper

    SciTech Connect

    Mortensen, A. [Massachusetts Inst. of Tech., Cambridge, MA (United States). Dept. of Materials Science and Engineering] [Massachusetts Inst. of Tech., Cambridge, MA (United States). Dept. of Materials Science and Engineering; Pedersen, O.B.; Lilholt, H. [Risoe National Lab., Roskilde (Denmark). Materials Dept.] [Risoe National Lab., Roskilde (Denmark). Materials Dept.

    1998-03-03

    The prediction and optimization of metal matrix composite mechanical behavior necessitates an understanding of the influence exerted by the reinforcement on matrix plastic deformation. This influence can be substantial, as was first eloquently shown in 1969 by Kelly and Lilholt. In this work, composites of continuous 10 and 20 {micro}m diameter tungsten fiber reinforced copper composites were produced and tested in tension along the fiber direction. This system was chosen for its simplicity, both in structure and in processing: copper and tungsten feature no mutual solubility nor intermetallic phases, and copper wets tungsten well. The composites were fabricated by spontaneous infiltration of molten copper into packed bundles of parallel fibers held within cylindrical molds, followed by directional solidification to ensure proper feeding of metal solidification shrinkage. Resulting composites were free of pores, and their matrix was found to be essentially monocrystalline. In processing the composites, the fiber volume fraction V{sub f} was carefully measured by counting the number of fibers in each preform, checking that the fiber diameter was in good agreement (within 1%) with the nominal fiber diameter. V{sub f} values thus determined were also verified using measurements of composite density, to find good agreement; quoted V{sub f} values can thus be deemed reliable. The aim of the present note is to propose an alternative explanation for the Stage II matrix hardening rates measured in infiltrated copper-tungsten composites. The explanation is close to the original interpretation, but proposes an observable physical basis for the occurrence of plastically non-yielding matrix regions in Stage II.

  11. Hardening transition in a one-dimensional model for ferrogels

    NASA Astrophysics Data System (ADS)

    Annunziata, Mario Alberto; Menzel, Andreas M.; Löwen, Hartmut

    2013-05-01

    We introduce and investigate a coarse-grained model for quasi one-dimensional ferrogels. In our description the magnetic particles are represented by hard spheres with a magnetic dipole moment in their centers. Harmonic springs connecting these spheres mimic the presence of a cross-linked polymer matrix. A special emphasis is put on the coupling of the dipolar orientations to the elastic deformations of the matrix, where a memory effect of the orientations is included. Although the particles are displaced along one spatial direction only, the system already shows rich behavior: as a function of the magnetic dipole moment, we find a phase transition between "soft-elastic" states with finite interparticle separation and finite compressive elastic modulus on the one hand, and "hardened" states with touching particles and therefore diverging compressive elastic modulus on the other hand. Corresponding phase diagrams are derived neglecting thermal fluctuations of the magnetic particles. In addition, we consider a situation in which a spatially homogeneous magnetization is initially imprinted into the material. Depending on the strength of the magneto-mechanical coupling between the dipole orientations and the elastic deformations, the system then relaxes to a uniaxially ferromagnetic, an antiferromagnetic, or a spiral state of magnetization to minimize its energy. One purpose of our work is to provide a largely analytically solvable approach that can provide a benchmark to test future descriptions of higher complexity. From an applied point of view, our results could be exploited, for example, for the construction of novel damping devices of tunable shock absorbance.

  12. Acute phase response of serum amyloid A protein and C reactive protein to the common cold and influenza

    Microsoft Academic Search

    J T Whicher; R E Chambers; J Higginson; L Nashef; P G Higgins

    1985-01-01

    C reactive protein (CRP) and serum amyloid A protein (SAA) are sensitive and rapid acute phase reactants, and their measurement for monitoring inflammatory disease and assessing the prognosis in secondary amyloidosis is gaining widespread acceptance. The changes in these proteins in eight subjects suffering from natural colds, 15 subjects with experimentally induced colds (rhinoviruses E1, 3, 9, 14, or 31),

  13. A search for the Mpemba effect: When hot water freezes faster then cold water James D. Brownridge

    E-print Network

    Suzuki, Masatsugu

    A search for the Mpemba effect: When hot water freezes faster then cold water James D. Brownridge 6000 Binghamton, New York 13902-6000, USA Abstract: An explanation for why hot water will sometime freeze more rapidly than cold water is offered. Two specimens of water from the same source will often

  14. Determination of Constant Parameters of Copper as Power-Law Hardening Material at Different Test Conditions

    NASA Astrophysics Data System (ADS)

    Kowser, Md. A.; Mahiuddin, Md.

    2014-11-01

    In this paper a technique has been developed to determine constant parameters of copper as a power-law hardening material by tensile test approach. A work-hardening process is used to describe the increase of the stress level necessary to continue plastic deformation. A computer program is used to show the variation of the stress-strain relation for different values of stress hardening exponent, n and power-law hardening constant, ? . Due to its close tolerances, excellent corrosion resistance and high material strength, in this analysis copper (Cu) has been selected as the material. As a power-law hardening material, Cu has been used to compute stress hardening exponent, n and power-law hardening constant, ? from tensile test experiment without heat treatment and after heat treatment. A wealth of information about mechanical behavior of a material can be determined by conducting a simple tensile test in which a cylindrical specimen of a uniform cross-section is pulled until it ruptures or fractures into separate pieces. The original cross sectional area and gauge length are measured prior to conducting the test and the applied load and gauge deformation are continuously measured throughout the test. Based on the initial geometry of the sample, the engineering stress-strain behavior (stress-strain curve) can be easily generated from which numerous mechanical properties, such as the yield strength and elastic modulus, can be determined. A universal testing machine is utilized to apply the load in a continuously increasing (ramp) manner according to ASTM specifications. Finally, theoretical results are compared with these obtained from experiments where the nature of curves is found similar to each other. It is observed that there is a significant change of the value of n obtained with and without heat treatment it means the value of n should be determined for the heat treated condition of copper material for their applications in engineering fields.

  15. Rapid direct determination using combined separation by prepared immunomagnetic and flow cytometry of Flavobacterium psychrophilum

    Microsoft Academic Search

    Kyoko Hibi; Kohji Mitsubayashi; Hideo Fukuda; Hideki Ushio; Tetsuhito Hayashi; Huifeng Ren; Hideaki Endo

    2007-01-01

    Flavobacterium psychrophilum, the causative agent of bacterial cold-water disease (BCWD), was originally isolated from coho salmon Oncorhychus kisutch in the USA. Bacterial cold-water disease has since been spreading throughout Japan and has caused serious damage to populations of ayu Plecoglossus altivel in many farms and rivers. The rapid method of detecting for F. psuchrophilum is requested, however, traditional methods are

  16. Cold plasma decontamination of foods.

    PubMed

    Niemira, Brendan A

    2012-01-01

    Cold plasma is a novel nonthermal food processing technology that uses energetic, reactive gases to inactivate contaminating microbes on meats, poultry, fruits, and vegetables. This flexible sanitizing method uses electricity and a carrier gas, such as air, oxygen, nitrogen, or helium; antimicrobial chemical agents are not required. The primary modes of action are due to UV light and reactive chemical products of the cold plasma ionization process. A wide array of cold plasma systems that operate at atmospheric pressures or in low pressure treatment chambers are under development. Reductions of greater than 5 logs can be obtained for pathogens such as Salmonella, Escherichia coli O157:H7, Listeria monocytogenes, and Staphylococcus aureus. Effective treatment times can range from 120 s to as little as 3 s, depending on the food treated and the processing conditions. Key limitations for cold plasma are the relatively early state of technology development, the variety and complexity of the necessary equipment, and the largely unexplored impacts of cold plasma treatment on the sensory and nutritional qualities of treated foods. Also, the antimicrobial modes of action for various cold plasma systems vary depending on the type of cold plasma generated. Optimization and scale up to commercial treatment levels require a more complete understanding of these chemical processes. Nevertheless, this area of technology shows promise and is the subject of active research to enhance efficacy. PMID:22149075

  17. Cold Spraying of Amorphous Cu50Zr50 Alloys

    NASA Astrophysics Data System (ADS)

    List, A.; Gärtner, F.; Mori, T.; Schulze, M.; Assadi, H.; Kuroda, S.; Klassen, T.

    2015-01-01

    A new range of applications in cold spraying is expected for bulk metallic glass (BMG) coatings. For retaining amorphous structures in cast multi-component BMG parts, typically high purity raw material must be used. The present investigation explores an alternative approach, where cold spraying is used to deposit a technical-grade binary amorphous alloy. This approach is shown to be potentially cost-effective and suitable for rapid manufacturing. For this purpose, amorphous Cu50Zr50 was chosen as a model alloy system, and cold spraying was performed using nitrogen as process gas. By a systematic variation of the spray parameter sets, the critical velocities for coating formation were determined experimentally. Based on the current models of bonding of amorphous Cu50Zr50 powder in cold spraying, a new, more comprehensive concept of bonding and rebound is presented, which also considers the presence of liquefied interfaces and quenching rates for resolidification. Results concerning impact morphologies and coating formation demonstrate that under suitable choice of spray conditions, well-adhering coatings with amorphous structure of the Cu50Zr50 powders can be obtained by cold spraying.

  18. Increase of cold tolerance in cotton plant (Gossypium hirsutum L.) by mepiquat chloride

    NASA Technical Reports Server (NTRS)

    Gausman, H. W.; Escobar, D. E.; Rodriguez, R. R. (principal investigators); Huang, S. Y.; Rittig, F. R.

    1982-01-01

    Three mepiquat chloride (MC) concentrations - 40, 70, and 100 g a.i./ha - were used to spray cotton (Gossypium hirsutum L., cultival McNair 220) plants to determine whether or not MC would increase their cold tolerance. Seven to ten days after the spray, the plants were exposed to three different cold treatments. No important difference in cold damage was noticed between the control and the MC-treated plants when they were exposed repeatedly to 4.5 C. No plants died when exposed to 0.5 C for 12 h; however, 90% of the 1st and 2nd leaves of the control plants were damaged. This was three times more damage than those leaves of plants treated with 70 and 100 g a.i./ha MC concentrations; 60% f the control and 10-20% of the MC-treated plants died when the plants were subjected to a cold hardening process with 15.5 C day (12 h) and 1.7 C night (12 h) for 10 days, and then, held at -2.2 C for 24 hours. The electrolyte leakage and reflectance measurement data showed that the cell membranes of the MC-treated plants sustained much less damage than those of the control. Freezing injury was easily assessed by reflectance measurements at the 1.65 micrometer wavelength.

  19. ON THE SPECTRAL HARDENING AT {approx}>300 keV IN SOLAR FLARES

    SciTech Connect

    Li, G.; Kong, X.; Zank, G. [Department of Physics and CSPAR, University of Alabama in Huntsville, Huntsville, AL 35899 (United States); Chen, Y., E-mail: gang.li@uah.edu [Institute of Space Sciences and School of Space Sciences and Physics, Shandong University, 264209 Weihai (China)

    2013-05-20

    It has long been noted that the spectra of observed continuum emissions in many solar flares are consistent with double power laws with a hardening at energies {approx}>300 keV. It is now widely believed that at least in electron-dominated events, the hardening in the photon spectrum reflects an intrinsic hardening in the source electron spectrum. In this paper, we point out that a power-law spectrum of electrons with a hardening at high energies can be explained by the diffusive shock acceleration of electrons at a termination shock with a finite width. Our suggestion is based on an early analytical work by Drury et al., where the steady-state transport equation at a shock with a tanh profile was solved for a p-independent diffusion coefficient. Numerical simulations with a p-dependent diffusion coefficient show hardenings in the accelerated electron spectrum that are comparable with observations. One necessary condition for our proposed scenario to work is that high-energy electrons resonate with the inertial range of the MHD turbulence and low-energy electrons resonate with the dissipation range of the MHD turbulence at the acceleration site, and the spectrum of the dissipation range {approx}k {sup -2.7}. A {approx}k {sup -2.7} dissipation range spectrum is consistent with recent solar wind observations.

  20. Effect of Retained Austenite Stabilized via Quench and Partitioning on the Strain Hardening of Martensitic Steels

    NASA Astrophysics Data System (ADS)

    de Moor, E.; Lacroix, S.; Clarke, A. J.; Penning, J.; Speer, J. G.

    2008-11-01

    A novel heat-treating process, quench and partitioning (Q&P), has been proposed as a fundamentally new way to produce martensitic microstructures containing retained austenite. The two-step process hypothesizes carbon enrichment of the austenite by decarburization of the martensite. Significant amounts of retained austenite have been measured in the final microstructure, although evidence for transition carbide formation in the martensite also exists. The mechanical properties obtained via Q&P are reported for a CMnAlSiP steel after intercritical annealing for A50 specimens. Tensile strength/total elongation combinations, ranging from 800 MPa/>25 pct to 900 MPa/20 pct to 1000 MPa/10 pct, indicate that Q&P is a viable way to produce high strength steel grades with good ductility. The instantaneous strain hardening of Q&P steels shows a significant dependence on the partitioning conditions applied. Lower partitioning temperature (PT) leads to continuously decreasing instantaneous n-values with strain, similar to the strain hardening behavior observed for dual-phase (DP) steels, whereas higher PTs for the same partitioning time increase the strain hardening significantly. After an initial increase, the observed n-values remain high up to considerable amounts of strain, resulting in similar strain hardening behavior observed for austempered transformation-induced plasticity (TRIP) grades. Assessment of the mechanical stability of the retained austenite indicates that the TRIP effect is effectively contributing to the increased strain hardening as function of strain.

  1. Deformation mechanisms, size effects, and strain hardening in nanoscale metallic multilayers under nanoindentation

    NASA Astrophysics Data System (ADS)

    Shao, S.; Zbib, H. M.; Mastorakos, I. N.; Bahr, D. F.

    2012-08-01

    The strain hardening and the related surface pile-up phenomena in CuNi, CuNb and CuNiNb nanoscale multilayered metallic (NMM) composites are investigated using atomistic simulations of nanoindentation on such multilayers with varying individual layer thickness. Using empirical load-stress and displacement-strain relations, the obtained load-depth curves were converted to hardness-strain curves which was then fitted using power law. It is found that the extent of surface pile-up is inversely related to the hardening exponent of the NMMs. Two deformations mechanisms which control the surface pile phenomenon are discovered and discussed. Furthermore, from the stress-strain data, it is found that interfaces and their types play a major role in strain hardening; the strain hardening rate increases with strain when incoherent interfaces are present. The relationship between the hardening parameters and the interfacial dislocation density as well as the relationship between interfacial density and length scales, such as layer thickness and indentation depth, are analyzed, and it is found that the hardness in these NMM has strong inverse power law dependence on the layer thickness.

  2. Alternating current potential drop for measuring the case depth of hardened steel

    NASA Astrophysics Data System (ADS)

    Quddes, Mohammad R.; Ji, Yuan; Bowler, John R.

    2015-03-01

    Multi-frequency alternate current potential drop measurements have been made to estimate the case depth of case hardened steels using four point probes. The probes have four parallel sprung loaded pins in a line with a 1.5 mm separation between the contact points. A printed circuit board has been used to ensure the electrical connections to the pins are close to the surface of the material. This has the effect of reducing the mutual induction between driver and pick-up pins. The case depth is estimated from measurements at frequencies typically from 10 Hz to 10 kHz. The real part of the voltage phasor representing the AC potential drop is used to evaluate the case depth. The imaginary part includes the contribution due to mutual induction. To estimate the case depth of the hardened samples, the measured potential drop has been fitted to theoretical predictions. The substrate material properties of the hardened samples are extracted from multi-frequency potential drop measurements on non-harden samples. The estimated case hardened depths, deduced from potential drop measurements, are similar to those found from destructive measurements.

  3. Method of warming cold engines in cold climates

    SciTech Connect

    Forschirm, A.

    1988-12-06

    This patent describes a method of warming cold engines in low temperature conditions comprising the steps of: (a) placing a flammable compound inside a nonflammable fabric bag; (b) placing the bag on an engine; and (c) igniting the flammable compound.

  4. Photosynthetic microorganisms in cold environments

    NASA Astrophysics Data System (ADS)

    Kviderova, Jana; Hajek, Josef; Elster, Josef; Bartak, Milos; Vaczi, Peter; Nedbalova, Linda

    The polar regions are considered as a model of extraterrestrial ecosystems. Depending on the average temperature, temperature variation and water availability, these conditions could be used as a model of Mars or Europa (e.g. (Elster and Benson, 2004). Two cases are presented: 1) Stable temperature and water availability The environment of cryosestic communities, i.e. organisms living in snow, is characterized by very stable temperature; the diurnal variations do not exceed 1 -2 ° C (Kváderová, 2010) and a are not usually exposed to freeze/thaw. Water is not usually limiting since the water content could reach up to 54 % (Nedbalová et al., 2008). The windblown sediments are important a source of nutrient and could provide protection against the excess of radiation. The nutrient concentrations in the snow are low are depleted rapidly when massive algal blooms forms. Such environment could be found near Mars polar caps or in Europa ice cover. The snow algae are the most important primary producers in snow. Their adaptation strategy is dependent on the developmental stages; the motile stages avoid the harsh conditions (e.g. high light) and sessile stages acclimatize to actual conditions. The main genera Chlamydomonas and Chloromonas (both Chlorophyta) are psychrophilic. Their growth optimum temperature is lower than 15 ° C and their growth is inhibited at temperatures above 20 ° C. 2) Unstable temperature and water availability The deglaciated surfaces, inhabited by lichen communities, are typical by variation in temper-ature and moisture. The temperature could range several tens ° C within a short time and the water availability is usually very limited. Due to temperature variation, the lichens are subjected to many freeze/thaw cycles. Such environments could be found in Martian deserts. The lichens are symbotic organisms composed of a mycobiont (heterotrophic fungi) and photo-bionts (algae and/or cyanobacteria). Majority of lichens are dehydrated in the field and their physiological processes are inactive. If hydrated, they are physiologically active even at subzero temperatures (Kappen et al., 1996). Although living in cold environments, the growth optimum temperature of typical phycobiont Trebouxia (Chlorophyta) sp. is above 15 ° C, so these algae are considered to be rather psychrotolerant. Acknowledgement The work was supported from projects GA AS CR Nos. KJB 601630808 and KJ KJB600050708, CAREX and long-term institutional research plan of the Institute of Botany AS CR AV0Z600050516 and the Masaryk University. Prof. Martin Backor (Safarik University in Kosice) is kindly ac-knowledged for providing the strains Trebouxia erici and T. glomerata (Backor). References Elster, J. , Benson, E.E. Life in the polar terrestrial environment with a focus on algae and cyanobacteria, in Fuller, B.J., Lane, N. , Benson, E.E. (Eds), Life in the Frozen State. CRC Press, pp. 111-150, 2004. Kappen, L., Schroeter, B., Scheidegger, C., Sommerkorn, M. , Hestmark, G. Cold resistance and metabolic activity of lichens below 0 ° C. Adv. Space Res. 18, 119-128, 1996. Kviderova, J. Characterization of the community of snow algae and their photochemical performance in situ in the Giant Mountains, Czech Republic. Arct. Antarct. Alp. Res. accepted, 2010. Nedbalova, L., Kocianova, M. , Lukavsky, J. Ecology of snow algae in the Giant Mountains and their relation to cryoseston in Europe. Opera Corcontica 45, 59-68, 2008.

  5. Plants in a cold climate.

    PubMed Central

    Smallwood, Maggie; Bowles, Dianna J

    2002-01-01

    Plants are able to survive prolonged exposure to sub-zero temperatures; this ability is enhanced by pre-exposure to low, but above-zero temperatures. This process, known as cold acclimation, is briefly reviewed from the perception of cold, through transduction of the low-temperature signal to functional analysis of cold-induced gene products. The stresses that freezing of apoplastic water imposes on plant cells is considered and what is understood about the mechanisms that plants use to combat those stresses discussed, with particular emphasis on the role of the extracellular matrix. PMID:12171647

  6. Deciphering the Metabolic Changes Associated with Diapause Syndrome and Cold Acclimation in the Two-Spotted Spider Mite Tetranychus urticae

    PubMed Central

    Khodayari, Samira; Moharramipour, Saeid; Larvor, Vanessa; Hidalgo, Kévin; Renault, David

    2013-01-01

    Diapause is a common feature in several arthropod species that are subject to unfavorable growing seasons. The range of environmental cues that trigger the onset and termination of diapause, in addition to associated hormonal, biochemical, and molecular changes, have been studied extensively in recent years; however, such information is only available for a few insect species. Diapause and cold hardening usually occur together in overwintering arthropods, and can be characterized by recording changes to the wealth of molecules present in the tissue, hemolymph, or whole body of organisms. Recent technological advances, such as high throughput screening and quantification of metabolites via chromatographic analyses, are able to identify such molecules. In the present work, we examined the survival ability of diapausing and non-diapausing females of the two-spotted spider mite, Tetranychus urticae, in the presence (0 or 5°C) or absence of cold acclimation. Furthermore, we examined the metabolic fingerprints of these specimens via gas chromatography-mass spectrophotometry (GC-MS). Partial Least Square Discriminant Analysis (PLS-DA) of metabolites revealed that major metabolic variations were related to diapause, indicating in a clear cut-off between diapausing and non-diapausing females, regardless of acclimation state. Signs of metabolic depression were evident in diapausing females, with most amino acids and TCA cycle intermediates being significantly reduced. Out of the 40 accurately quantified metabolites, seven metabolites remained elevated or were accumulated in diapausing mites, i.e. cadaverine, gluconolactone, glucose, inositol, maltose, mannitol and sorbitol. The capacity to accumulate winter polyols during cold-acclimation was restricted to diapausing females. We conclude that the induction of increased cold hardiness in this species is associated with the diapause syndrome, rather than being a direct effect of low temperature. Our results provide novel information about biochemical events related to the cold hardening process in the two-spotted spider mite. PMID:23349779

  7. Deciphering the metabolic changes associated with diapause syndrome and cold acclimation in the two-spotted spider mite Tetranychus urticae.

    PubMed

    Khodayari, Samira; Moharramipour, Saeid; Larvor, Vanessa; Hidalgo, Kévin; Renault, David

    2013-01-01

    Diapause is a common feature in several arthropod species that are subject to unfavorable growing seasons. The range of environmental cues that trigger the onset and termination of diapause, in addition to associated hormonal, biochemical, and molecular changes, have been studied extensively in recent years; however, such information is only available for a few insect species. Diapause and cold hardening usually occur together in overwintering arthropods, and can be characterized by recording changes to the wealth of molecules present in the tissue, hemolymph, or whole body of organisms. Recent technological advances, such as high throughput screening and quantification of metabolites via chromatographic analyses, are able to identify such molecules. In the present work, we examined the survival ability of diapausing and non-diapausing females of the two-spotted spider mite, Tetranychus urticae, in the presence (0 or 5°C) or absence of cold acclimation. Furthermore, we examined the metabolic fingerprints of these specimens via gas chromatography-mass spectrophotometry (GC-MS). Partial Least Square Discriminant Analysis (PLS-DA) of metabolites revealed that major metabolic variations were related to diapause, indicating in a clear cut-off between diapausing and non-diapausing females, regardless of acclimation state. Signs of metabolic depression were evident in diapausing females, with most amino acids and TCA cycle intermediates being significantly reduced. Out of the 40 accurately quantified metabolites, seven metabolites remained elevated or were accumulated in diapausing mites, i.e. cadaverine, gluconolactone, glucose, inositol, maltose, mannitol and sorbitol. The capacity to accumulate winter polyols during cold-acclimation was restricted to diapausing females. We conclude that the induction of increased cold hardiness in this species is associated with the diapause syndrome, rather than being a direct effect of low temperature. Our results provide novel information about biochemical events related to the cold hardening process in the two-spotted spider mite. PMID:23349779

  8. Influence of Cold Air Intrusions on the Wet Season Onset over Amazonia

    Microsoft Academic Search

    Wenhong Li; Rong Fu

    2006-01-01

    Using 15-yr data from the European Centre for Medium-Range Weather Forecasts Re-Analysis (ERA-15), the authors found that rapid southeastward expansion of the rainy area from the western Amazon to southeastern Brazil is a result of midlatitude cold air intrusions. During austral spring, as the large-scale thermodynamic structure over Amazonia becomes destabilized, the incursions of extratropical cold air can trigger intense

  9. First Year: Clear, cold day

    E-print Network

    Chapman, Michael S.

    First Year: A Gap [I] Clear, cold day Girl sitting on the corner Pile of stained napkins Bright red is invading my brain But Somewhere between the Knowing and Helping There is a gap. By Julia Armendariz, MS1

  10. Gastrointestinal bleeding after cold biopsy.

    PubMed

    Vu, C K; Korman, M G; Bejer, I; Davis, S

    1998-07-01

    Cold biopsy of the gastric mucosa is useful in many gastroduodenal disorders. Antral biopsies are done with increasing frequency to confirm Helicobacter pylori infection and to determine the type and content of gastritis. Gastrointestinal bleeding after gastric cold biopsy is rare. We report two patients who developed melena after cold biopsy of the gastric antrum. Repeat gastroscopies excluded lesions other than the biopsied sites as the source of bleeding. Colonoscopies in both cases did not reveal any evidence of lower GI bleed. Relevant medications include amlodipine, in case 1, and brufen, which was used in case 2 but discontinued before biopsy. Literature review has shown the rarity of clinically significant hemorrhage resulting from gastric cold biopsy. Nevertheless, all patients undergoing gastroscopy should be informed of this potential complication. PMID:9672346

  11. Probing the Strain Hardening Response of Small Wear Volumes with Nanoindentation

    NASA Astrophysics Data System (ADS)

    Cordill, M. J.; Moody, N. R.; Jungk, J. M.; Kennedy, M. S.; Mook, W. M.; Prasad, S. V.; Bahr, D. F.; Gerberich, W. W.

    2011-08-01

    In order to characterize the wear and related mechanical behavior of materials from small volumes, a program employing nanoscratch and nanoindentation was performed. Nanoscratch techniques were used to generate square wear patterns with varying degrees of shear strain followed by nanoindentation tests to measure the mechanical properties within the deformation area. Results show a systematic increase in hardness with both the applied load and number of nanoscratch passes. An analytical approach was used to determine the stress-strain response and strain hardening behavior of electroformed nickel. The strain hardening exponent determined from this method follows the work hardening behavior established from previous tensile tests, supporting the use of a nanomechanics-based approach for evaluating the mechanical properties of wear-tested material.

  12. Engineering design guidelines for electromagnetic pulse hardening of naval equipment. Final report

    SciTech Connect

    Rogers, S.R.; Perala, R.A.; Rosich, R.K.; Cook, R.B.; Rudolph, T.H.

    1981-07-15

    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.

  13. Analysis of the infrared spectrum and microstructure of hardened cement paste

    SciTech Connect

    Gao, X.F.; Lo, Y.; Tam, C.M.; Chung, C.Y. (City Univ. of Hong Kong (Hong Kong))

    1999-06-01

    Phase transformation was found in hardened cement paste exposed to dynamic loading caused by typhoon and the normal static-dynamic loading. The concrete samples were obtained from a 20-year-old residential building. The bonding characteristics and microstructure of the hardened cement paste with different loading history have been carefully studied using scanning electron microscopy analysis and infrared spectrum technique. The scanning electron microscopy micrographs indicate that there is a morphological difference in the concrete microstructure. The infrared spectrum analysis has provided information for understanding the phase transformation characteristics of the primary bonds and secondary bonds. This has led to the establishment of a microscopic model describing the correlation between the behavior of the hydrate lime and the properties of the hardened cement paste.

  14. Considerations for the application and numerical implementation of strain hardening with the Hoffman yield criterion

    SciTech Connect

    Li, X.; Duxbury, P.G.; Lyons, P. [Dalian Univ. of Technology, Dalian (China)

    1994-08-01

    This paper extends the work of Schellekens and De Borst (Comput. Struct. 37, 1087-1096 (1989)) on the Hoffman yield criterion, which defines the anisotropic yield of nonlinear materials, to include a straightforward representation of strain hardening. Various special cases of the Hoffman criterion are considered with regard to the use of internal state variables to quantify the evolution of the yield surface as strain hardening progresses. One of these forms of strain hardening is then adopted and a fully consistent formulation derived. The formulation consists of an implicit return mapping algorithm at the Gauss point level in which a stress state satisfying the yield criterion is found. In addition, a consistent tangent for use in global structural iterations, in which the displacements are sought as the primary unknowns, is derived. Finally, some numerical examples are presented using the general purpose FE package LUSAS in which the algorithm has been implemented. 7 refs.

  15. Design of a total-dose radiation hardened monolithic CMOS DC-DC boost converter

    NASA Astrophysics Data System (ADS)

    Zhi, Liu; Hongying, Ning; Hongbo, Yu; Youbao, Liu

    2011-07-01

    This paper presents the design and implementation of a monolithic CMOS DC-DC boost converter that is hardened for total dose radiation. In order to improve its radiation tolerant abilities, circuit-level and device-level RHBD (radiation-hardening by design) techniques were employed. Adaptive slope compensation was used to improve the inherent instability. The H-gate MOS transistors, annular gate MOS transistors and guard rings were applied to reduce the impact of total ionizing dose. A boost converter was fabricated by a standard commercial 0.35 ?m CMOS process. The hardened design converter can work properly in a wide range of total dose radiation environments, with increasing total dose radiation. The efficiency is not as strongly affected by the total dose radiation and so does the leakage performance.

  16. A nonlinear kinematic hardening model for elastoplastic deformations in grey cast iron

    SciTech Connect

    Josefson, B.L.; Hjelm, H.E. [Chalmers Univ. of Technology, Goeteborg (Sweden). Div. of Solid Mechanics; Stigh, U. [Hoegskolan i Skoevde (Sweden). Dept. of Engineering Science

    1995-04-01

    A kinematic hardening model including an associated flow rule is proposed for elastoplastic deformations in graphitic grey cast iron. Quantitatively good results are obtained when comparing with previously performed biaxial experiments. Use of a nonassociated flow rule is found to result in an undesirable weakening behavior that can be explained as a deficiency with the combination of kinetic hardening and the present choice of yield potential. The model proposed is also extended to include multilinear kinematic hardening. With this model qualitatively good agreement with experimental cyclic results from the literature is obtained. A three-dimensional FE-analysis of a cylinder head for a heavy duty Diesel engine is performed as an application. To predict initiation of thermal fatigue cracks, it is essential to use an elastoplastic material model.

  17. Strength, Hardening, and Failure Observed by In Situ TEM Tensile Testing**

    PubMed Central

    Kiener, Daniel; Kaufmann, Petra; Minor, Andrew M.

    2012-01-01

    We present in situ transmission electron microscope tensile tests on focused ion beam fabricated single and multiple slip oriented Cu tensile samples with thicknesses in the range of 100–200 nm. Both crystal orientations fail by localized shear. While failure occurs after a few percent plastic strain and limited hardening in the single slip case, the multiple slip samples exhibit extended homogenous deformation and necking due to the activation of multiple dislocation sources in conjunction with significant hardening. The hardening behavior at 1% plastic strain is even more pronounced compared to compression samples of the same orientation due to the absence of sample taper and the interface to the compression platen. Moreover, we show for the first time that the strain rate sensitivity of such FIB prepared samples is an order of magnitude higher than that of bulk Cu. PMID:23447712

  18. Influence of explosive density on mechanical properties of high manganese steel explosion hardened

    NASA Astrophysics Data System (ADS)

    Hu, Xiaoyan; Shen, Zhaowu; Liu, Yingbin; Liu, Tiansheng; Wang, Fengying

    2013-12-01

    The explosion hardening tests of high manganese steel were carried out by using two kinds of explosives of the same composition but different density, respectively. The detonation velocities were tested and the relevant mechanical properties were studied. The results show that the stronger single impulse acting on the specimen, the more hardness of surface increases and the more impact toughness decreases. Compared with the explosive of 1.48 g/cm3 density, the hardness, elongation rate, and impact toughness of the sample for triple explosion with explosive of 1.38 g/cm3 density are larger at the same hardening depth. In addition, the tensile strength of the sample for triple explosion with density of 1.38 g/cm3 is higher from the surface to 15 mm below the surface hardened.

  19. Ferrous arrowheads and their oil quench hardening: Some early Indian evidence

    NASA Astrophysics Data System (ADS)

    Dube, R. K.

    2008-05-01

    A wide variety of ferrous arrowheads were in use in ancient India. Several typical chemical analyses of arrowheads found from archaeological excavation carried out at Kaushambi are reported in this paper. The average carbon content of these arrowheads varied from as low as 0.1 wt.% to approximately 0.9 wt.%. Literary evidence for oil quench hardening of ferrous arrowheads, as reported in famous Sanskrit epics—the R?m?yana and the Mah?bh?rata—have been discussed in this paper. This type of quench hardening was intentionally adopted as it helped in preventing distortion and formation of quench cracks in arrowheads. The oil quench-hardened arrowheads were rubbed on stones to sharpen them, which also brought about tempering of martensite due to frictional heat.

  20. A Users manual for the nonlinear kinematic hardening model for cyclic loading

    SciTech Connect

    Puso, M

    2000-09-15

    This report describes the implementation of the Chaboche type Nonlinear Kinematic Hardening Model developed for the PNGV SPP (Partnership for the Next Generation Vehicle, Spring-back Predictability Project). The material model includes a nonlinear kinematic and isotropic hardening law, transverse anisotropy, strain range memorization for cyclic hardening/softening and viscoplasticity. This report is a companion to the report: ''A Return Mapping Algorithm for Cyclic Viscoplastic Constitutive Models'' which concentrates on the theoretical aspects of the model. This report summarizes the necessary parameters for the model, briefly discusses their interpretation and shows some numerical simulations. The report also specifies the data structure requirements for linking the material model software by explicitly referencing the source code delivered to the SPP collaborators.

  1. Sinusitis in the common cold

    Microsoft Academic Search

    Tuomo Puhakka; Mika J. Mäkelä; Anu Alanen; Timo Kallio; Leo Korsoff; Pertti Arstila; Maija Leinonen; Markku Pulkkinen; Jouko Suonpää; Jussi Mertsola; Olli Ruuskanen

    1998-01-01

    Background: Acute community-acquired sinusitis is considered a bacterial complication of the common cold. Radiologic abnormalities in sinuses occur, however, in most patients with upper respiratory virus infections.Objective: Assessment of the occurrence, clinical profile, laboratory findings, and outcome of radiologically confirmed sinusitis was carried out as part of a common cold study in young adults.Methods: Clinical examinations and radiography of the

  2. Cold regions hydrology and hydraulics

    SciTech Connect

    Ryan, W.L. (HDR Engineers, Inc., Anchorage, AK (US)); Crissman, R.D. (NY Power Authority, Niagra Falls, NY (US))

    1990-01-01

    This monograph addresses a narrow aspect of cold regions engineering, namely the effects of cold weather on the traditional civil engineering disciplines of hydrology and hydraulics. Hydrologic and hydraulic considerations in the design, construction, and operation of civil works are very important. Many of the problems encountered in the design and construction of buildings, transportation systems, water supply facilities, waste treatment facilities, and hazardous waste disposal facilities, for example are closely tied to the characteristics of the site hydrology.

  3. Antibiotic use for common cold

    Microsoft Academic Search

    Timothy W. Kenealy; Bruce Arroll

    Antibiotics do not help patients with an uncomplicated common cold. Antibiotics can have side effects for the individual taking\\u000a them that range from unpleasant to serious, even lethal. Antibiotic use also contributes to communal harm by encouraging antibiotic\\u000a resistance. If there can be no benefit, but there can be harm, why is the common cold the commonest reason for doctors

  4. Mass spectrometry-based metabolomic fingerprinting for screening cold tolerance in Arabidopsis thaliana accessions.

    PubMed

    Vaclavik, Lukas; Mishra, Anamika; Mishra, Kumud B; Hajslova, Jana

    2013-03-01

    The availability of rapid and reliable tools for monitoring of plants' cold tolerance is a prerequisite for research aimed at breeding of cold-tolerant crop plants. Therefore, we have tested the capacity of metabolomics-based methods employing ultra-high-performance liquid chromatography (UHPLC)-mass spectrometry and direct analysis in real time-mass spectrometry for high-throughput screening of cold tolerance in eight differentially cold-tolerant accessions of Arabidopsis thaliana. Metabolomic fingerprinting of leaf tissues was performed in methanolic extracts for (1) 6-week-old non-acclimated (NAC) plants grown at room temperature, (2) NAC plants cold-acclimated (ACC) at 4 °C for 2 weeks, and (3) cold-acclimated plants given sub-zero-temperature treatments by slow cooling at -4 °C for 8 h. The generated chromatograms and mass spectra were processed with the use of multivariate statistical analysis employing principal component analysis (PCA) and linear discriminant analysis. The PCA of metabolomic fingerprints classified the investigated A. thaliana accessions into three categories with low, intermediate, and high cold tolerance for both the cold-acclimated and the sub-zero-temperature-treated plants. This indicates the potential application of metabolomics-based fingerprinting for measuring cold tolerance in the cold-acclimated state, i.e., without treating plants at freezing temperatures that is required by currently available methods. Furthermore, we employed UHPLC coupled to the quadrupole-time-of-flight mass spectrometry to identify characteristic metabolites in ACC state and found the abundance of gluconapin and flavon-3-ol glycosides, respectively, in the cold-sensitive and the cold-tolerant accessions. PMID:23325403

  5. The effect of microstructural evolution on hardening behavior of type 17-4PH stainless steel in long-term aging at 350 deg. C

    SciTech Connect

    Wang Jun [School of Materials Science and Engineering, Sichuan University, Chengdu, 610065 (China) and Nuclear Power Institute of China, Chengdu, 610041 (China)]. E-mail: srwangjun@163.com; Zou Hong [Nuclear Power Institute of China, Chengdu, 610041 (China); Li Cong [Nuclear Power Institute of China, Chengdu, 610041 (China); Qiu Shaoyu [Nuclear Power Institute of China, Chengdu, 610041 (China); Shen Baoluo [School of Materials Science and Engineering, Sichuan University, Chengdu, 610065 (China)

    2006-12-15

    The effect of microstructural evolution on hardening behavior of 17-4PH stainless steel in long-term aging at 350 deg. C was studied by X-ray diffraction and transmission electron microscopy. The results showed that there is the matrix of lath martensite and nanometer-sized particles of {epsilon}-Cu precipitated from the matrix after the alloy is solution treated and tempered. When the alloy was aged 350 deg. C for 9 months, {alpha}-{alpha}' spinodal decomposition occurred along the grain boundaries and caused an increase in hardness which compensated for the weakening effect due to ripening of the {epsilon}-copper precipitates. Upon further aging to 12 months, the Cr-rich {alpha}'-phase and M{sub 23}C{sub 6} precipitated, both of which strengthened the alloy considerably and led to enhanced hardening despite the continued softening by overaging of the {epsilon}-copper precipitates. With the aging time extended to 15 months, substantial reversed austenite transformed and precipitation of the intermetallic G-phase occurred near the {epsilon}-Cu precipitates in the matrix. The abundant amount of reversed austenite that transformed led to rapid softening.

  6. Release of ovoperoxidase from sea urchin eggs hardens the fertilization membrane with tyrosine crosslinks

    PubMed Central

    Foerder, Charles A.; Shapiro, Bennett M.

    1977-01-01

    One feature of fertilization is the alteration of the vitelline layer, by components released from the egg, to produce an elevated, covalently crosslinked, hard, insoluble, fertilization membrane. The following evidence indicates that crosslinking and hardening are caused by the production of diand trityrosyl residues, by oxidation of protein-bound tyrosyl residues in the presence of a peroxidase. Hardening of the fertilization membrane, as evidenced by its loss of solubility in 50 mM dithiothreitol, is inhibited by compounds known to inhibit many peroxidases. A peroxidase, here called the ovoperoxidase, is released from eggs at fertilization. This enzyme is inhibited by the same compounds that inhibit hardening and at similar concentrations. Inhibitors of the ovoperoxidase and the hardening reaction include KCN, 3-amino-1,2,4-triazole, NaN3, phenylhydrazine, K4Fe(CN)6, sodium sulfite, and glycine ethyl ester. In addition, tyramine and N-acetyltyrosine both inhibit hardening, but O-methyltyrosine does not. Dityrosyl and trityrosyl residues are found in acid hydrolysates of isolated, hardened fertilization membranes. These residues have been identified by cellulose phosphate column chromatography, thin-layer chromatography, and amino acid analysis. The amino acid data have been used to estimate that there is one dityrosine crosslink per 55,000 daltons of protein. We suggest that, by catalyzing the crosslinking of tyrosyl residues, the ovoperoxidase leads to the production of a hard fertilization membrane that blocks the entry of additional sperm. Because peroxidases are spermicidal, a secondary function of the enzyme could be to kill sperm in the vicinity of the fertilized egg. Images PMID:270665

  7. Deep Drawing Simulation Of High And Ultrahigh Strength Steels Under Consideration Of Anisotropic Hardening

    NASA Astrophysics Data System (ADS)

    Roll, Karl; Faust, Alexander; Keßler, Lutz

    2007-05-01

    In today's sheet metal forming simulation, most attention is paid to yield loci functions, which describe the anisotropy of the material in yielding. The coefficients, defining the shape of the yield locus in these functions are usually fitted at a certain level of plastic work and are then valid for the whole range of plastic deformation. Modern high and ultrahigh strength steels, especially those with induced plasticity, may often exhibit only a very small anisotropy in yielding, but a severe anisotropy in work hardening for different loading conditions. This behavior can not be described by fitting the yield locus at a specific value of plastic deformation. An approach to take into account the anisotropic hardening of sheet metals is to provide different yield curves for several loading conditions and expand the yield locus dependent on the current form of load. By doing this, one can use a comparatively simple yield locus, like that of Hill from 1948, because all anisotropy is given by the different hardening curves. For the commercial FEM code LS DYNA the material model MATFEM Generalized Yield is available as a user subroutine, which supports this approach. In this paper, forming simulation results of different yield loci are compared with experimental results. The simulations were carried out in LS-DYNA with the Barlat 89 and 2000 yield loci and isotropic hardening and with the GenYld model combining a Hill 48 yield locus and anisotropic hardening. The deep drawing experiments were conducted on a hydraulic press, measuring binder and punch forces. The deformation of the sheet was measured by optical grid analysis. A comparison of the simulated and measured plastic strains shows that using a model including anisotropic hardening can produce better results than the usage of a complex yield locus but isotropic hardening for the examined materials. This might be interesting for e.g. spring back simulations. By combining a simple yield locus with anisotropic hardening an effective way for industrial part simulation seems to be available, which does not require the consideration of thermal effects or crystal plasticity.

  8. Mechanical properties of friction stir welded Al alloys with different hardening mechanisms

    Microsoft Academic Search

    Sunggon Lim; Sangshik Kim; Chang-Gil Lee; Sung Joon Kim

    2005-01-01

    The mechanical properties of precipitation hardened Al 6061-T651 and Al 7075-T6 and strain hardened Al 5083-H32, friction\\u000a stir welded with various welding parameters, were examined in the present study. 4 mm thick Al 6061-T651, Al 7075-T6, and\\u000a Al 5083-H32 alloy plates were used for friction stir welding (FSW) with rotating speed varied from 1000 to 2500 rpm (rotation\\u000a per minute)

  9. Influence of ageing treatment on work hardening behavior of a Ni-base superalloy

    SciTech Connect

    Singh, P.N.; Singh, V. [Banaras Hindu Univ., Varanasi (India)] [Banaras Hindu Univ., Varanasi (India)

    1996-06-15

    A large number of superalloys have been developed for application in gas turbine aero engines; among these, Nimonic alloy 263 (C-263) is an important precipitation hardening nickel base superalloy, with high creep strength and oxidation resistance, designed for stationary components like combustion chamber, casing, liner, exhaust ducting, bearing housing and many others. The purpose of the present investigation is to examine the work hardening behavior of the alloy 263, following solution treatment at 1,150 C and ageing for different periods at 800 C.

  10. Application of corotational rates of the logarithmic strain in constitutive modeling of hardening materials at finite deformations

    Microsoft Academic Search

    R. Naghdabadi; M. Yeganeh; A. R. Saidi

    2005-01-01

    In this paper a finite deformation constitutive model for rigid plastic hardening materials based on the logarithmic strain tensor is introduced. The flow rule of this constitutive model relates the corotational rate of the logarithmic strain tensor to the difference of the deviatoric Cauchy stress and the back stress tensors. The evolution equation for the kinematic hardening of this model

  11. Nuclear thermal effects on the outer material of the blast hardened S-280 electrical shelter wall. Final report

    Microsoft Academic Search

    Quigley

    1977-01-01

    Because of the thermal insulating nature of the Kevlar-49 fiber epoxy resin composite material used in the blast hardened S-280 electrical shelter with the blast hardened wall and roof construction of the shelter, the shelter will survive the recommended nuclear thermal radiation levels. However, since the thermal environment precedes the blast environment and the Kevlar material is an integral part

  12. Enhanced fatigue resistance of a nickel-based hastelloy induced by a surface nanocrystallization and hardening process

    Microsoft Academic Search

    J. C. Villegas; L. L. Shaw; K. Dai; W. Yuan; J. Tian; P. K. Liaw; D. L. Klarstrom

    2005-01-01

    Improvements in the fatigue resistance of a nickel-based alloy have been achieved via a surface nanocrystallization and hardening (SNH) process. The enhanced fatigue resistance is related to the surface nanocrystallization, work hardening, and compressive residual stresses induced by the SNH process.

  13. Enhanced fatigue resistance of a nickel-based hastelloy induced by a surface nanocrystallization and hardening process

    NASA Astrophysics Data System (ADS)

    Villegas, J. C.; Shaw, L. L.; Dai, K.; Yuan, W.; Tian, J.; Liaw, P. K.; Klarstrom, D. L.

    Improvements in the fatigue resistance of a nickel-based alloy have been achieved via a surface nanocrystallization and hardening (SNH) process. The enhanced fatigue resistance is related to the surface nanocrystallization, work hardening, and compressive residual stresses induced by the SNH process.

  14. Authigenic Carbonate Constructions From Deep Sea Cold Seeps

    NASA Astrophysics Data System (ADS)

    Pierre, C.; Bouloubassi, I.

    2008-12-01

    Various examples of authigenic carbonates from modern marine cold seeps have been described worldwide on active or passive continental margins. They may be associated or not with gas hydrates. After a decade of microbiological and geochemical studies, we know that in cold seep marine environments, methane and other hydrocarbon compounds contained in the ascending fluids are oxidized as CO2 by a microbial consortium of sulfate reducing bacteria and methanotrophic archea. The Anaerobic Oxidation of Methane (AOM) represents the main microbial process driving the precipitation of authigenic carbonate crusts and concretions within the subsurface anoxic sediments. This explains why sea floor is often hardened by carbonate constructions at the sites of active methane seepage. The lateral and vertical extensions of these carbonate constructions are controlled by the balance between the intensity of the venting fluid flux and the ability of microbial communities to oxidize methane and to reduce sulfate. At steady state, the microbial filter transforms the totality of the emitted methane and generates carbonate; however, the efficiency of this filter can be counteracted by high methane flux, so that methane can escape in the water column and eventually reach the atmosphere ; numerical modelling of carbonate crust formation has shown that bioturbation and sedimentation rates are also important factors that control fluid and methane flow rates and thus carbonate precipitation at cold seep sites. The carbonate constructions observed at the sea floor exhibit various morphologies : massive to porous crusts, cm to meters thick, forming large pavements or fragmented slabs, circular chimneys, irregular concretions corresponding to cemented bioturbations. These hard substrates are often colonized by fixed organisms as polychaetes, tube-worms, molluscs, as well as by an abundant vagile fauna. The authigenic carbonates represent very useful archives to reconstruct the story of the seep activity. Their mineralogy, geochemical and isotopic compositions depend on the composition of the fluids and thus provide information of the origin of these fluids. It is noteworthy to mention that carbonate minerals are generally dominated by aragonite and Mg-calcite although dolomite and ankerite may become the unique species as in the carbonate chimneys of the Gulf of Cadiz. All cold seep carbonates are characterized by very low ?13C values down to - 60 permil clearly indicating that they were methane-derived products. The lipid biomarkers that are entrapped in the carbonate network provide the complementary information of the composition of the microbial communities that were involved during the diagenetic processes, AOM, sulfate reduction and methanogenesis.

  15. A multidisciplinary approach to the identification and evaluation of novel concepts for deeply buried hardened target defeat

    NASA Astrophysics Data System (ADS)

    Branscome, Ewell Caleb

    During the Cold War, Deeply Buried Hardened Targets (DBHTs) and the assets they protected were of great strategic and tactical concern to the Department of Defense. Megaton-class nuclear warheads were the only viable means of attacking many of these facilities, and even so, a small subset of DBHTs was anticipated to be robust even in the face of such an attack. Post Cold War, the threat posed by DBHTs has not disappeared. Rather, the conventional warfare advantages of the United States have led to an increasing emphasis by potential adversaries on the construction and use of hardened facilities such as DBHTs for protection of both conventional and unconventional assets. Further, the shift in perceived relative risk to the United States' national security from large scale all-out nuclear attack towards very limited attack by Weapons of Mass Destruction (WMD) has led some to hypothesize that "self-deterrence" may diminish the strategic value of current inventory nuclear weapons. The objective of the work described was to identify and explore a paradigm shifting solution that could offer leap-ahead capabilities to counter current and future DBHT threats while mitigating or eliminating the "self-deterrence" issue. Systematic evaluation of DHBT defeat alternatives lead to the selection of a thermal subterrene as a hypothetical means of providing such a capability. A number of possible implementation alternatives for a thermal subterrene were investigated, resulting in the identification of the RadioIsotope Powered Thermal Penetrator (RIPTP) concept for providing an effectively unlimited hard rock penetration capability using near-term technologies. However, the proposed approach was novel and thus required formulation and application of a physics based multidisciplinary analysis code to enable evaluation of lv design alternatives and analysis of performance. Technical considerations identified as important to the feasibility of a RIPTP for DBHT defeat included: packing of RIPTP components in available volume; close-contact melting in a medium with nonlinear thermodynamic properties; radiation shielding; radiation health physics; point source plume dispersal calculations; alternative technologies for production of radioisotopes; chemical and physical properties of isotope compounds; nuclear reactor characteristics; high temperature material stability and inter-material compatibility; weapon and delivery system integration; a variety of heat transfer regimes including radiation, conduction, convection, nucleate boiling, and film boiling; thermal/mechanical stress analysis (steady-state and transient); rock physical and thermodynamic properties as a function of temperature; detection/mapping of deeply buried facility spaces; and more. The following disciplinary analyses were composed into a multidisciplinary analysis code for a RIPTP: packing of RIPTP components in available volume; close-contact melting analysis; transmutation of isotope species by neutron activation; reactor neutron economy; radioisotope power generation through decay; metamodelled radiation shielding calculations for a RIPTP; and steady state thermal analyses for a RIPTP in various scenarios. Filtering of radioisotopes for potential suitability, their possible production mechanisms, state of technological development, and multidisciplinary analysis code predicted performance lead to the identification of Thulium-170 as the best isotope for powering a RIPTP using present-day technology and technical data. Ytterbium-169 was identified as an alternative isotope offering the potential for significant potential improvements over Thulium-170 in radiological safety as well as RIPTP performance and producibility. Production, however, was determined to require identification of a cost effective technology for highly enriching Ytterbium-168 from its low natural abundance. Performance analysis of the identified baseline Thulium-170 RIPTP suggested that the predicted low penetration rate of about 10 meters/day could be a significant negative factor wi

  16. Development of a Rapid-Start On-Board Automotive Steam Reformer

    SciTech Connect

    Whyatt, Greg A.; Fischer, Christopher M.; Davis, James M.

    2004-04-29

    The paper reports on the status of efforts to engineer a microchannel steam reforming system to enable a rapid cold start capability. The steam reformer is intended to be coupled with a WGS and PROX reactor to provide reformate to a PEM fuel cell for an automotive propulsion application. A compact and efficient microchannel steam reformer was previously developed that required ~15 minutes to accomplish a cold start. The objective of the current work was to reduce this start time to <30 seconds without sacrificing steady-state efficiency. The paper describes the changes made in the reforming system to enable cold start capability and presents data on reformate flow and temperature transients during cold start testing. The results demonstrate that the system is capable of producing reformate within 22 seconds after a cold start. A strategy for integrating the system with a WGS and PROX reactor to provide a rapid start fuel processing system is described.

  17. Relationships between cold hardiness, and ice nucleating activity, glycerol and protein contents in the hemolymph of caterpillars, Aporia crataegi L.

    PubMed

    Li, N G

    2012-01-01

    Insects in Siberia must tolerate some of the coldest conditions on earth. The relationship between hemolymph ice nucleating activity, glycerol and total protein concentrations, and cold hardiness was explored in Aporia crataegi L. (Lepidoptera: Pieridae). Cold-hardened overwintering caterpillars were collected at a time of year when temperatures are regularly below -50 degree C, and warm-acclimated at +22 degree C, to see how changes in the physical and chemical properties of the hemolymph influence their cold hardiness potential. Warm acclimation led to a decrease in glycerol and proteins content in the hemolymph, which was associated with the decrease in ice nucleating activity and dramatic loss of cold hardiness potential of the caterpillars. It is suggested that one of the effects of cryoprotection in the freeze tolerant insects, caused by glycerol, might be associated with its ability to form larger aggregates of ice nucleating polypeptides that initiate the ice nucleation at high subzero temperatures. Such ice nucleating structures seem to ensure a high probability of ice nucleation at relatively high temperatures, which may contribute to the extraordinary cold hardiness of A. crataegi caterpillars, which may tolerate temperatures below -85 degree ?. PMID:22576117

  18. Rapid Prototyping: Lessons Learned

    Microsoft Academic Search

    V. Scott Gordon; James M. Bieman

    1995-01-01

    Rapid prototyping is a development method that may or may not be e ective in improving software products and process. Assessing the e ectiveness of rapid prototyping requires empirical data. We analyze 39 published and unpublished \\\\real world\\

  19. TEM investigation of age-hardenable Al 2519 alloy subjected to stress corrosion cracking tests

    Microsoft Academic Search

    Stanis?aw Dymek; Marek Dollar

    2003-01-01

    The influence of changes in chemical composition and pre-aging deformation on the resistance to stress corrosion cracking in the age-hardenable aluminum alloy 2519 was investigated by transmission electron microscopy. The improvement of this resistance may be accomplished by keeping the Cu concentration on the lower side of the allowed limit for the 2519 alloy. Also, plastic deformation prior to aging,

  20. The development of high strength corrosion resistant precipitation hardening cast steels

    Microsoft Academic Search

    Rachel A. Abrahams

    2010-01-01

    Precipitation Hardened Cast Stainless Steels (PHCSS) are a corrosion resistant class of materials which derive their properties from secondary aging after a normalizing heat treatment step. While PHCSS materials are available in austenitic and semi-austenitic forms, the martensitic PHCSS are most widely used due to a combination of high strength, good toughness, and corrosion resistance. If higher strength levels can

  1. Formation of the anion structure of calcium hydrosilicates in hardening of slag cements

    Microsoft Academic Search

    N. S. Nikonova; V. V. Mityushin; I. N. Tikhomirova; V. I. Prikhno

    1993-01-01

    The characteristics of formation of the phase composition and anion structure of hydrate formations in hardening of composites\\u000a based on granulated electrothermal phosphorus slag and self-slaking ferrochrome slag mixed with a solution of sodium sulfate\\u000a were examined.

  2. Efficient simulation of press hardening process through integrated structural and CFD analyses

    NASA Astrophysics Data System (ADS)

    Palaniswamy, Hariharasudhan; Mondalek, Pamela; Wronski, Maciek; Roy, Subir

    2013-12-01

    Press hardened steel parts are being increasingly used in automotive structures for their higher strength to meet safety standards while reducing vehicle weight to improve fuel consumption. However, manufacturing of sheet metal parts by press hardening process to achieve desired properties is extremely challenging as it involves complex interaction of plastic deformation, metallurgical change, thermal distribution, and fluid flow. Numerical simulation is critical for successful design of the process and to understand the interaction among the numerous process parameters to control the press hardening process in order to consistently achieve desired part properties. Until now there has been no integrated commercial software solution that can efficiently model the complete process from forming of the blank, heat transfer between the blank and tool, microstructure evolution in the blank, heat loss from tool to the fluid that flows through water channels in the tools. In this study, a numerical solution based on Altair HyperWorks® product suite involving RADIOSS®, a non-linear finite element based structural analysis solver and AcuSolve®, an incompressible fluid flow solver based on Galerkin Least Square Finite Element Method have been utilized to develop an efficient solution for complete press hardening process design and analysis. RADIOSS is used to handle the plastic deformation, heat transfer between the blank and tool, and microstructure evolution in the blank during cooling. While AcuSolve is used to efficiently model heat loss from tool to the fluid that flows through water channels in the tools. The approach is demonstrated through some case studies.

  3. A Combined Precipitation, Yield Strength, and Work Hardening Model for Al-Mg-Si Alloys

    NASA Astrophysics Data System (ADS)

    Myhr, Ole Runar; Grong, Øystein; Pedersen, Ketill Olav

    2010-09-01

    In the present article, a new two-internal-variable model for the work hardening behavior of commercial Al-Mg-Si alloys at room temperature is presented, which is linked to the previously developed precipitation and yield strength models for the same class of alloys. As a starting point, the total dislocation density is taken equal to the sum of the statistically stored and the geometrically necessary dislocations, using the latter parameters as the independent internal variables of the system. Classic dislocation theory is then used to capture the overall stress-strain response. In a calibrated form, the work hardening model relies solely on outputs from the precipitation model and thus exhibits a high degree of predictive power. In addition to the solute content, which determines the rate of dynamic recovery, the two other microstructure parameters that control the work hardening behavior are the geometric slip distance and the corresponding volume fraction of nonshearable Orowan particles in the base material. Both parameters are extracted from the predicted particle size distribution. The applicability of the combined model is illustrated by means of novel process diagrams, which show the interplay between the different variables that contribute to work hardening in commercial Al-Mg-Si alloys.

  4. Coupling Effects of Hardening and Damage on Necking and Bursting Conditions in Sheet Metal Forming

    Microsoft Academic Search

    S. Thibaud; N. Boudeau; J. C. Gelin

    2004-01-01

    New materials are appearing for sheet metal components. Their use in automotive industry require careful analysis of the influence of initial and induced properties on the formability and risks of failure during the process. The proposed approach is based on experimental investigations, mechanical modelling and FE simulations to analyse the effects of hardening and damage on the development of necking,

  5. Impurity-defect interactions and radiation hardening and embrittlement in BCC metals

    Microsoft Academic Search

    M. S. Wechsler; K. L. Murty

    1989-01-01

    The interaction of interstitial impurity atoms (IIA's) with radiation-produced defects in bcc metals and its influence on radiation hardening and embrittlement are reviewed. Special emphasis is placed on the role of oxygen in vanadium and niobium and of nitrogen and carbon in iron and steel. Upon postirradiation annealing at temperatures where the IIA's are mobile (about 50 °C to 250

  6. Hardening Fingerprint Fuzzy Vault Using Password Karthik Nandakumar, Abhishek Nagar and Anil K. Jain

    E-print Network

    Hardening Fingerprint Fuzzy Vault Using Password Karthik Nandakumar, Abhishek Nagar and Anil K in biometric systems because biometric templates are non-revocable. Fuzzy vault is a cryptographic framework vault framework has proven security properties, it does not provide privacy-enhancing features

  7. Helium ion irradiation induced swelling and hardening in commercial and experimental ODS steels

    NASA Astrophysics Data System (ADS)

    Fave, Loïc; Pouchon, Manuel A.; Döbeli, Max; Schulte-Borchers, Martina; Kimura, Akihiro

    2014-02-01

    The radiation resistance of two promising ferritic ODS steels, PM2000 and 15CRA-3, is studied. More specifically, the effect of helium on these materials is studied by examining the swelling and hardening after He+ implantation to ˜1 dpa at 4000 appm/dpa.

  8. Cyclic Material Properties Test to Determine Hardening/Softening Characteristics of HY-80 Steel

    SciTech Connect

    S.C. Hodge; J.M. Minicucci; T.F. Trimble

    2003-04-30

    The Cyclic Material Properties Test was structured to obtain and provide experimental data for determining cyclic hardening/softening characteristics of HY-80 steel. The inelastic strain history data generated by this test program and the resulting cyclic stress-strain curve will be used to enhance material models in the finite element codes used to perform nonlinear elastic-plastic analysis.

  9. Localization of plastic deformation along grain boundaries in a hardening material

    Microsoft Academic Search

    Y.-L Shen; W Li; D. L Sulsky; H. L Schreyer

    2000-01-01

    The deformation characteristics of ductile polycrystalline materials at elevated temperatures were studied numerically by considering a square segment of material subjected to different stress modes. The initial polycrystalline microstructure was generated numerically. The micromechanical modeling of the deformation was performed using the material point method. The constitutive behavior was taken to be isotropic, elastic–plastic with linear hardening. To effectively simulate

  10. Beam hardening correction for a cone-beam CT system and its effect on spatial resolution

    NASA Astrophysics Data System (ADS)

    Zhao, Wei; Fu, Guo-Tao; Sun, Cui-Li; Wang, Yan-Fang; Wei, Cun-Feng; Cao, Da-Quan; Que, Jie-Min; Tang, Xiao; Shi, Rong-Jian; Wei, Long; Yu, Zhong-Qiang

    2011-10-01

    In this paper, we present a beam hardening correction (BHC) method in three-dimension space for a cone-beam computed tomography (CBCT) system in a mono-material case and investigate its effect on the spatial resolution. Due to the polychromatic character of the X-ray spectrum used, cupping and streak artifacts called beam hardening artifacts arise in the reconstructed CT images, causing reduced image quality. In addition, enhanced edges are introduced in the reconstructed CT images because of the beam hardening effect. The spatial resolution of the CBCT system is calculated from the edge response function (ERF) on different planes in space. Thus, in the CT images with beam hardening artifacts, enhanced ERFs will be extracted to calculate the modulation transfer function (MTF), obtaining a better spatial resolution that deviates from the real value. Reasonable spatial resolution can be obtained after reducing the artifacts. The 10% MTF value and the full width at half maximum (FWHM) of the point spread function with and without BHC are presented.

  11. Nondestructive Monitoring of Setting and Hardening of Portland Cement Mortar with Sonic Methods

    E-print Network

    post-tensioning with greatest efficiency. A nondestructive, ultrasonic technique, which measures, USA Abstract The setting and hardening process of concrete is considered to be the most critical time period during the life of a concrete structure. Previous research has been conducted on an ultrasonic

  12. In situ self hardening bioactive composite for bone and dental surgery.

    E-print Network

    Paris-Sud XI, Université de

    1 In situ self hardening bioactive composite for bone and dental surgery. R. Turczyn1 , P. Weiss3 to the reconstruction of bone tissue in orthopaedic surgery, stomatology and dental applications rely on calcium facilitates the penetration of cells and biological growth factors in the implant. The osteogenesis process

  13. Properties of metakaolin geopolymer hardened paste prepared by high-pressure compaction

    Microsoft Academic Search

    Vladimír Živica; Svetozar Balkovic; Milan Drabik

    2011-01-01

    The paper presents the results of the study on the effects of the combination of the low liquid\\/solid (l\\/s) ratio and pressure compaction of the fresh pastes on the properties of the hardened metakaolin geopolymer paste. It is well known that the combination gives the possibility to prepare cement composites resulting in the excellent engineering properties. The results obtained shown

  14. Surface transformation hardening on steels treated with solar energy in central tower and heliostats field

    Microsoft Academic Search

    G. P. Rodríquez; V. López; J. J. de Damborenea; A. J. Vázquez

    1995-01-01

    The possibility of surface hardening on AISI 4140 steel treated with concentrated solar energy in solar installations for electricity production has been studied. The samples were slides from a 35 mm diameter steel bar and their height was 35 mm. The quenching was made in water but also was considered the possibility of self-quenching by cooling in air. The amount

  15. The surface fatigue life of contour induction hardened AISI 1552 gears

    NASA Astrophysics Data System (ADS)

    Townsend, Dennis P.; Turza, Alan; Chaplin, Mike

    1995-07-01

    Two groups of spur gears manufactured from two different materials and heat treatments were endurance tested for surface fatigue life. One group was manufactured from AISI 1552 and was finished ground to a 0.4 micron (16 micro-in.) rms surface finish and then dual frequency contour induction hardened. The second group was manufactured from CEVM AISI 9310 and was carburized, hardened, and ground to a 0.4 micron (16 micro-in.) rms surface finish. The gear pitch diameter was 8.89 cm (3.5 in.). Test conditions were a maximum Hertz stress of 1.71 GPa (248 ksi), a bulk gear temperature of approximately 350 K (170 F) and a speed of 10,000 rpm. The lubricant used for the tests was a synthetic paraffinic oil with an additive package. The test results showed that the 10 percent surface fatigue (pitting) life of the contour hardened AISI 1552 test gears was 1.7 times that of the carburized and hardened AISI 9310 test gears. Also there were two early failures of the AISI 1552 gears by bending fatigue.

  16. Modeling strain hardening and texture evolution in friction stir welding of stainless steel

    Microsoft Academic Search

    Jae-Hyung Cho; Donald E. Boyce; Paul R. Dawson

    2005-01-01

    Steady-state friction stir welding of stainless steel has been modeled using an Eulerian formulation that considers coupled viscoplastic flow and heat transfer in the vicinity of the tool pin. Strain hardening is incorporated with a scalar state variable that evolves with deformation as material moves along streamlines of the flow field. The model equations are solved using the finite element

  17. A bimodal energy model for correcting beam hardening artefacts in X-ray tomography

    Microsoft Academic Search

    Elke Van de Casteele; Dirk Van Dyck; Jan Sijbers; Erik Raman

    2003-01-01

    As a consequence of the polychromatic X-ray sources, used in micro-computer tomography (?CT) and in medical CT, the attenuation is no longer a linear function of absorber thickness. If this nonlinear beam hardening effect is not compensated, the reconstructed images will be corrupted by cupping artefacts. Here, a bimodal energy model for the energy spectrum is presented, which may be

  18. Fast and innovative determination of parameters for steel hardening with high power diode lasers

    Microsoft Academic Search

    Steffen Bonss; Gunther Goebel; Marko Seifert; Berndt Brenner; Eckhard Beyer

    2003-01-01

    Laser Beam Hardening with High Power Diode Lasers is presented as an excellent method for local heat treatment and minimum distortion. An overview is given about several strategies for local heat treatment and different industrial applications. Precise measuring and controlling of the surface temperature makes the process very reliable and is an essential tool for industrial users. To keep a

  19. 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 ?' (Mg2Si) precipitates and the precipitation of non-hardening ?' (Mg2Si) precipitates during the weld thermal cycles to quantitatively prove above mentioned advantageous characteristics of laser beam welding.

  20. Exploring Visitor Acceptability for Hardening Trails to Sustain Visitation and Minimise Impacts

    Microsoft Academic Search

    Kerri L. Cahill; Jeffrey L. Marion; Steven R. Lawson

    2008-01-01

    Protected natural area managers are challenged to provide high quality recreation opportunities and ensure the protection of resources from impacts associated with visitation. Development of visitor use facilities and application of site hardening practices are commonly applied tools for achieving these competing management objectives. This study applies stated choice analysis to examine visitor opinions on acceptability when they are asked

  1. Radiation-hardened integrated circuit amplifier: Nuclear weapon effects susceptibility study

    Microsoft Academic Search

    W. L. Vault; L. Harper

    1976-01-01

    The objective of this program was to measure the permanent degradation and transient circuit response of a radiation-hardened operational amplifier, developed for long-wave infrared (LWIR) sensors, to simulate nuclear weapon effects environments. These included transient radiation effects (TRE), system-generated electromagnetic pulse (SGEMP), and combined nuclear radiation and electrical pulse effects.

  2. Strain hardening and large tensile elongation in ultrahigh-strength nano-twinned copper

    Microsoft Academic Search

    E. Ma; Y. M. Wang; Q. H. Lu; M. L. Sui; L. Lu; K. Lu

    2004-01-01

    A high density of growth twins in pure Cu imparts high yield strength while preserving the capacity for efficient dislocation storage, leading to high strain hardening rates at high flow stresses, especially at 77 K. Uniform tensile deformation is stabilized to large plastic strains, resulting in an ultrahigh tensile strength of ~1 GPa together with an elongation to failure of

  3. Studies on Age Hardening for Improvement of 6261 and 6060 Extruded Aluminium Alloys

    NASA Astrophysics Data System (ADS)

    Au, Ka Ki (Katie); Hodgson, Michael; Pasang, Timotius; Chiu, Yu Lung

    The magnesium silicide precipitates in the 6XXX series alloy are the main components contributing to the heat treatable properties and T6 strength of the alloy, which is influenced by the size, morphology and distribution of this phase. During the extrusion process, the strength contributing phase, magnesium silicide is supposed to dissolve and form again in a controlled state during age hardening. Whereas the intermetallic AlFeSi phase has little if any influence on the strength, the ? phase of this intermetallic is known to cause brittle fracture of this alloy, as opposed to the less detrimental, more equiaxed ? phase formed during homogenisation. This study investigates the as-extruded 6060 and the more heavily alloyed 6261 aluminium alloys, as well as the subsequent heat treated forms to investigate the ageing conditions to optimise hardening and shorten age hardening times for higher cost effectiveness. The microstructure, texture and precipitate size and distributions were studied using optical microscopy, SEM, EBSD and DSC. SEM and EDAX results have indicated signs of evenly distributed ? AlFeSi and ? Magnesium Silicide precipitates. The phase responsible for hardening is believed to be the much smaller scaled ?" magnesium silicide, requiring much higher resolution studies.

  4. Tensile Properties and Work Hardening Behavior of Laser-Welded Dual-Phase Steel Joints

    NASA Astrophysics Data System (ADS)

    Farabi, N.; Chen, D. L.; Zhou, Y.

    2012-02-01

    The aim of this investigation was to evaluate the microstructural change after laser welding and its effect on the tensile properties and strain hardening behavior of DP600 and DP980 dual-phase steels. Laser welding led to the formation of martensite and significant hardness rise in the fusion zone because of the fast cooling, but the presence of a soft zone in the heat-affected zone was caused by partial vanishing and tempering of the pre-existing martensite. The extent of softening was much larger in the DP980-welded joints than in the DP600-welded joints. Despite the reduction in ductility, the ultimate tensile strength (UTS) remained almost unchanged, and the yield strength (YS) indeed increased stemming from the appearance of yield point phenomena after welding in the DP600 steel. The DP980-welded joints showed lower YS and UTS than the base metal owing to the appearance of severe soft zone. The YS, UTS, and strain hardening exponent increased slightly with increasing strain rate. While the base metals had multi-stage strain hardening, the welded joints showed only stage III hardening. All the welded joints failed in the soft zone, and the fracture surfaces exhibited characteristic dimple fracture.

  5. Solid solution softening and hardening in the Nb-O system

    Microsoft Academic Search

    G. W. Bang; J. Nagakawa; M. Meshii

    1980-01-01

    It is demonstrated that, in niobium, the interstitial O atoms cause the softening and hardening effect similar to the self-interstitials generated by low temperature electron irradiation. The stress-strain curves of crystals with two tensile axis orientations are shown. Their deformation behavior was quite different. (FS)

  6. ORIGINAL PAPER Combined effects of pre-hardening and fall fertilization

    E-print Network

    ORIGINAL PAPER Combined effects of pre-hardening and fall fertilization on nitrogen translocation status is important for outplanting success. Fall fertilization of evergreen conifer seedlings is a well, the interaction of N status prior to fall fertilization and the rate of fall fertilization have yet to be fully

  7. Finite Element Analysis of Composite Hardened Walls Subjected to Blast Loads

    Microsoft Academic Search

    S. Urgessa

    2009-01-01

    Problem statement: There is currently no standard design guideline to determine the number of composites needed to retrofit masonry walls in order to withstand a given explosion. Past design approaches were mainly based on simplified single-degree-of-freedom analysis. A finite element analysis was conducted for concrete masonry walls hardened with composites and subjected to short duration blast loads. Approach: The analysis

  8. Risk Analysis and Probabilistic Survivability Assessment (RAPSA): An Assessment Approach for Power Substation Hardening1

    Microsoft Academic Search

    Carol Taylor; Axel Krings; Jim Alves-Foss

    In this paper we present a new cyber security assessment approach, which merges Survivability System Analysis (SSA) with Probability Risk Assessment (PRA). The method adds quantitative information to the process oriented SSA method, which assists with decision making among security options. Our technique is currently being developed for power industry cyber security assessment and hardening. A substation example is presented,

  9. Identification of the hardening law of materials with spherical indentation using the average

    E-print Network

    products. This mechanical property is commonly obtained from tensile test. For cases such as plastically and functionally graded materials, biomedical materials, welded components and thin films, the tensile test cannot tensile test [1­9] . Identification of plastic hardening parameters from a load-penetration depth

  10. Budding and domain shape transformations in mixed lipid films and bilayer membranes J. L. Harden*

    E-print Network

    MacKintosh, F.C.

    Budding and domain shape transformations in mixed lipid films and bilayer membranes J. L. Harden shape. With increasing line tension, we show numerically that there is a budding transformation from stable protruding circular domains to spherical buds. We calculate the full phase diagram and demonstrate

  11. Copper precipitation in cobalt-alloyed precipitation-hardened stainless steel

    E-print Network

    Medvedeva, Julia E.

    Copper precipitation in cobalt-alloyed precipitation-hardened stainless steel Arpana S. Murthy online 1 March 2012 The influence of cobalt addition on precipitation of copper in a high-strength stainless steel was investigated using three-dimen- sional atom probe tomography. A decrease in copper

  12. Fresh and hardened properties of self-compacting concrete produced with manufactured sand

    Microsoft Academic Search

    Prakash Nanthagopalan; Manu Santhanam

    2011-01-01

    Self-compacting concrete (SCC) is extensively applied in many construction projects due to its excellent fresh and hardened concrete properties. In recent years, manufactured sand (Msand) produced by crushing rock deposits is being identified as a suitable alternative source for river sand in concrete. The main objective of this study is to explore the possibility of using Msand in SCC. In

  13. Effect of Oil Palm Fiber Fuel Ash on Compressive Strength of Hardening Concrete

    Microsoft Academic Search

    Danupon Tonnayopas; Kanung Putto

    The effects of oil palm fiber fuel ash (OPFFA) on the compressive strength of hardening concrete under uniaxial compression are investigated. The OPFFA was differently replaced Portland cement of 5, 10, 15, 20, 25 and 30% by weight. The test has been conducted on the concrete specimens on cured 7 periods of 0, 3, 7, 14, 21, 60, and 90

  14. Surface hardening of duplex stainless steel by low temperature active screen plasma nitriding

    Microsoft Academic Search

    Kimiaki Nagatsuka; Akio Nishimoto; Katsuya Akamatsu

    2010-01-01

    The duplex stainless steel has high strength and excellent corrosion resistance. Since this steel has low hardness and wear resistance, the surface hardening treatment should be carried out under the wear environment. In this study, plasma nitriding has been applied for the improvement of wear resistance. However, traditional plasma nitriding at temperatures ranging from 723 to 823K decreases the corrosion

  15. Hardening a Soft Budget Constraint Through 'Upward Devolution' to a Supranational Institution

    Microsoft Academic Search

    Elisabetta Bertero; Laura Rondi

    This paper contributes to the literature on the role of decentralization in hardening the budget constraint of public enterprises. Following Qian and Roland the study adopts a 'federalist' approach. However, it interprets federalism as the upward devolution of domestic economic policies to a supranational authority and examines its role in disciplining public enterprises operating in a soft budget regime. The

  16. A phenomenological model of size-dependent hardening in crystal plasticity

    Microsoft Academic Search

    P. J. Guruprasad; A. A. Benzerga

    2008-01-01

    A phenomenological model of plastic deformation is proposed, which captures the size-dependence of plastic flow strength and work-hardening in pure FCC crystalline materials. Guided by discrete dislocation dynamics analyses, the treatment is based on two structural variables determining the mechanical state of the material. A complete description of plastic behaviour is achieved, giving two inherently different statements for the evolution

  17. Characterization of Radiation Hardened Bipolar Linear Devices for High Total Dose Missions

    NASA Technical Reports Server (NTRS)

    McClure, Steven S.; Harris, Richard D.; Rax, Bernard G.; Thorbourn, Dennis O.

    2012-01-01

    Radiation hardened linear devices are characterized for performance in combined total dose and displacement damage environments for a mission scenario with a high radiation level. Performance at low and high dose rate for both biased and unbiased conditions is compared and the impact to hardness assurance methodology is discussed.

  18. Use of thermally reactive powders for hardening steel and cast iron parts

    Microsoft Academic Search

    A. A. Zhukov; E. P. Shilina; G. A. Chernaya

    1988-01-01

    The problem of surface hardening of working organs of earth-movlng machinery and many parts of tractors and agricultural machines should be dealt with using the least expensive constructional materials and treatments. The inexpensive and nonstrategic mixtures described in this article were first used successfully for the surface alloying of steel castings [I]. The mixtures are thermally reactive, but the thermal

  19. "Deviance Proneness" and Adolescent Smoking 1980 versus 2001: Has There Been a "Hardening" of Adolescent Smoking?

    ERIC Educational Resources Information Center

    Chassin, Laurie; Presson, Clark; Morgan-Lopez, Antonio; Sherman, Steven J.

    2007-01-01

    In a midwestern community sample, we tested for evidence of "hardening" of adolescent cigarette smoking between 1980 and 2001 by comparing adolescent smokers and nonsmokers at these two times on measures indicative of "deviance proneness" in Jessor and Jessor's [Jessor, R., & Jessor, S. L. (1977). "Problem behavior and psychosocial development: A…

  20. The effect of strain hardening on resistance to electrochemical corrosion of wires for orthopaedics

    Microsoft Academic Search

    J Przondziono; W Walke; E Hadasik; J Szymszal

    2012-01-01

    The purpose of this research is to evaluate electrochemical corrosion resistance of wire with modified surface, made of stainless steel of Cr-Ni-Mo type, widely used in implants for orthopaedics, depending on hardening created in the process of drawing. Tests have been carried out in the environment imitating human osseous tissue. Pitting corrosion was determined on the ground of registered anodic

  1. Proposed radiation hardened mobile vehicle for Chernobyl dismantlement and nuclear accident response

    Microsoft Academic Search

    M. S. Rowland; M. A. Holliday; J. A. Karpachov; A. Ivanov

    1995-01-01

    Researchers are developing a radiation hardened, Telerobotic Dismantling System (TDS) to remediate the Chernobyl facility. To withstand the severe radiation fields, the robotic system, will rely on electrical motors, actuators, and relays proven in the Chernobyl power station. Due to its dust suppression characteristics and ability to cut arbitrary materials the authors propose using a water knife as the principle

  2. Effect of surface work hardening on wear behavior of Hadfield steel

    Microsoft Academic Search

    Weilin Yan; Liang Fang; Kun Sun; Yunhua Xu

    2007-01-01

    Shot peening has become an effective method to strengthen alloy. In this investigation, it has been used to work-harden Hadfield steel. It has been regarded that the surface hardness of Hadfield steel has been increased greatly after shot peening. Using electron scanning microscope (SEM), high resolution transmission electron microscope (HRTEM) and X-ray diffraction (XRD) analysis, the microstructure of shot penned

  3. 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.

  4. Role of electron concentration in softening and hardening of ternary molybdenum alloys

    Microsoft Academic Search

    J. R. Stephens; W. R. Witzke

    1975-01-01

    Effects of various combinations of hafnium, tantalum, rhenium, osmium, ; iridium, and platinum in ternary molybdenum alloys on alloy softening and ; hardening were determined. Hardness tests were conducted at four test ; temperatures over the temperature range 77 to 411°K. Results showed that ; hardness data for ternary molybdenum alloys could be correlated with anticipated ; results from binary

  5. Correlation of tensile and flexural responses of strain softening and strain hardening cement composites

    E-print Network

    Mobasher, Barzin

    con- ducted in tension or flexure. Fig. 1a presents tensile stress­strain response as compared to equivalently elastic flexural stress vs. deflection of Alkali Resistant (AR) glass fabric reinforced compositeCorrelation of tensile and flexural responses of strain softening and strain hardening cement

  6. Investigation of the effects of the surface nanocrystallization and hardening (SNH) process on bulk metallic components

    NASA Astrophysics Data System (ADS)

    Villegas Palacio, Juan Carlos

    2005-07-01

    Bulk metallic components with a grain size gradient ranging from nanocrystalline at the surface to coarse grained in the bulk and superior hardness properties have been obtained with the Surface Nanocrystallization and Hardening (SNH) process. The evolution of surface topography and microstructural characteristics, as well as mechanical properties, have been studied as a function of processing parameters employing a variety of analytical techniques. Connections between microstructural features, observed hardness behavior and potentially active hardening mechanisms have been made, arriving at the conclusion that deformation-twin-dominated work hardening is responsible for the 140% increase in hardness displayed by SNH-processed specimens. A grain-refinement mechanism led by multiple deformation micro- and nano-scale twinning and complemented by dislocation activity has been put forth in order to explain the nanocrystallization of the coarse-grained material employed in this investigation. Potential harm from contamination at the processed surface has been assessed and its detrimental effects on the performance of treated components have been discussed. Finally, a few lines of work aimed at further exploring, understanding and exploiting the benefits of the Surface Nanocrystallization and Hardening process have been suggested.

  7. Investigation of the effects of the surface nanocrystallization and hardening (SNH) process on bulk metallic components

    Microsoft Academic Search

    Juan Carlos Villegas Palacio

    2005-01-01

    Bulk metallic components with a grain size gradient ranging from nanocrystalline at the surface to coarse grained in the bulk and superior hardness properties have been obtained with the Surface Nanocrystallization and Hardening (SNH) process. The evolution of surface topography and microstructural characteristics, as well as mechanical properties, have been studied as a function of processing parameters employing a variety

  8. Analysis of residual stresses in main crankshaft bearings after induction surface hardening and finish grinding

    Microsoft Academic Search

    J Grum

    2003-01-01

    The exact pattern of residual stresses will depend on the heat treatment temperatures employed, the depth of hardening and the type of quenchant. Process conditions that give rise to compressive residual stresses on the surface of heat-treated components are favourable. This type of residual stress delays the initiation of fatigue cracking in service, which typically occurs on the surface ofthe

  9. Residual stress relaxation and fatigue behavior of an induction hardened microalloyed steel

    Microsoft Academic Search

    Ana Luisa Rivas De Rivas

    1998-01-01

    The thermal and mechanical relaxation of compressive residual stresses during tempering and cyclic loading of an induction hardened vanadium microalloyed steel has been evaluated. A microstructural analysis was also carried out on the microalloyed steel to correlate the residual stress relaxation behavior with microstructural characteristics of the material. Vanadium carbide particle size and distribution were analyzed as well as how

  10. Optimization of conditions of preparation of dispersion-hardened copper-base alloys

    Microsoft Academic Search

    Z. M. Lovshenko; F. G. Lovshenko; G. F. Kovalevskii; Yu. I. Kolmykov

    1983-01-01

    The object of the work described below was to develop an effective method of producing dispersion-hardened copper-base alloys possessing a satisfactory combination of physicomechanical properties. The process chosen for this purpose consists in mechanical alloying, involving intense mixing and milling of starting powders in order to obtain a homogeneous composite, the resultant mixture being then subjected to internal oxidation [I].

  11. A new reverse analysis to determine the constitutive response of plastically graded case hardened bearing steels

    Microsoft Academic Search

    Nathan A. Branch; Ghatu Subhash; Nagaraj K. Arakere; Michael A. Klecka

    2011-01-01

    A new reverse analysis is presented that determines the plastic response of both nongraded and plastically graded materials (PGMs) without the need for traditional tension or compression tests. The method utilizes the concepts of expanding cavity model for strain hardening materials, Tabor’s rule of converting Vickers hardness to flow stress, representative plastic strain induced by indentation, and finite element modeling

  12. The effect of cyclic loading on the irradiation hardening of type 316L stainless steel

    Microsoft Academic Search

    R. Scholz

    1997-01-01

    Strain controlled fatigue tests have been performed in torsion on annealed type 316L stainless steel irradiated with 19 MeV deuterons at 400°C for shear strain ranges between 0.95% and 1.4%. The irradiation hardening of the material was suppressed to a great extent for continuous cycling conditions in comparison to hold time tests.

  13. Multi-species beam hardening calibration device for x-ray microtomography

    NASA Astrophysics Data System (ADS)

    Evershed, Anthony N. Z.; Mills, David; Davis, Graham

    2012-10-01

    Impact-source X-ray microtomography (XMT) is a widely-used benchtop alternative to synchrotron radiation microtomography. Since X-rays from a tube are polychromatic, however, greyscale `beam hardening' artefacts are produced by the preferential absorption of low-energy photons in the beam path. A multi-material `carousel' test piece was developed to offer a wider range of X-ray attenuations from well-characterised filters than single-material step wedges can produce practically, and optimization software was developed to produce a beam hardening correction by use of the Nelder-Mead optimization method, tuned for specimens composed of other materials (such as hydroxyapatite [HA] or barium for dental applications.) The carousel test piece produced calibration polynomials reliably and with a significantly smaller discrepancy between the calculated and measured attenuations than the calibration step wedge previously in use. An immersion tank was constructed and used to simplify multi-material samples in order to negate the beam hardening effect of low atomic number materials within the specimen when measuring mineral concentration of higher-Z regions. When scanned in water at an acceleration voltage of 90 kV a Scanco AG hydroxyapatite / poly(methyl methacrylate) calibration phantom closely approximates a single-material system, producing accurate hydroxyapatite concentration measurements. This system can then be corrected for beam hardening for the material of interest.

  14. Application of a kinematic hardening viscoplasticity model with thresholds to the residual stress relaxation

    Microsoft Academic Search

    J. L. Chaboche; O. Jung

    1997-01-01

    The life analysis of engine components needs to take into account the residual stress relaxation induced by cyclic service loads. The paper recalls a new class of constitutive equations for cyclic viscoplasticity, using a series of kinematic hardening models with thresholds. The equations are introduced within a recently enlarged thermodynamic framework. Some attention is focused to the relations with multisurface

  15. Parameter determination of Chaboche kinematic hardening model using a multi objective Genetic Algorithm

    Microsoft Academic Search

    A. H. Mahmoudi; S. M. Pezeshki-Najafabadi; H. Badnava

    2011-01-01

    Chaboche model is a powerful tool to evaluate the cyclic behavior under different loading conditions using kinematic hardening theory. It can also predict the ratcheting phenomenon. To predict the ratcheting, it is required to determine the material parameters under strain control conditions. Although, these parameters can model the hysteresis loop fairly accurately, their ratcheting prediction does not have the same

  16. Digital ASIC Architectures : Realtime Time-Frequency Analysis and Radiation Hardening

    E-print Network

    Baudoin, Geneviève

    Digital ASIC Architectures : Realtime Time-Frequency Analysis and Radiation Hardening Lead: L needs of TFR analysis lead to the design of an application specific integrated circuit (ASIC on our cascadable prototype ASIC, manufactured in ST 130 process. This work was done while L. Noury

  17. Investigation of the correlation between thermal properties and hardenability of Jominy bars quenched with air–water mixture for AISI 1050 steel

    Microsoft Academic Search

    Mehmet Çakir; Abdullah Özsoy

    2011-01-01

    In this study, the hardenability of AISI 1050 steel has been investigated in different cooling media using Jominy test. The temperature values were recorded using the thermocouples that were placed on sample. The relations between the cooling media and the cooling curves, heat flux, hardenability and heat convection coefficient were shown in graphics. The correlation between thermal properties and hardenability

  18. Ghabezloo et al. (2008): The effect of undrained heating on a fluid-saturated hardened cement paste The effect of undrained heating on a fluid-saturated

    E-print Network

    Paris-Sud XI, Université de

    2008-01-01

    Ghabezloo et al. (2008): The effect of undrained heating on a fluid-saturated hardened cement paste 150 The effect of undrained heating on a fluid-saturated hardened cement paste Siavash Ghabezloo*(1 and the effect of undrained heating is studied experimentally for a saturated hardened cement paste. The measured

  19. Liquation Microfissuring in the Weld Heat-Affected Zone of an Overaged Precipitation-Hardened Nickel-Base Superalloy

    NASA Astrophysics Data System (ADS)

    Ojo, O. A.; Chaturvedi, M. C.

    2007-02-01

    The effect of preweld overaging heat treatment on the microstructural response in the heat-affected zone (HAZ) of a precipitation-hardened nickel-base superalloy INCONEL 738LC subjected to the welding thermal cycle ( i.e., rapid) was investigated. The overaging heat treatment resulted in the formation of an interfacial microconstituent containing M23X6 particles and coarsening of primary and secondary ?' precipitates. The HAZ microstructures around welds in the overaged alloy were simulated using the Gleeble thermomechanical simulation system. Microstructural examination of simulated HAZs and those present in tungsten inert gas (TIG) welded specimens showed the occurrence of extensive grain boundary liquation involving liquation reaction of the interfacial microconstituents containing M23X6 particles and MC-type carbides. In addition, the coarsened ?' precipitate particles present in the overaged alloy persisted well above their solvus temperature to temperatures where they constitutionally liquated and contributed to considerable liquation of grain boundaries, during continuous rapid heating. Intergranular HAZ microfissuring, with resolidified product formed mostly on one side of the microfissures, was observed in welded specimens. This suggested that the HAZ microfissuring generally occurred by decohesion across one of the solid-liquid interfaces during the grain boundary liquation stage of the weld thermal cycle. Correlation of simulated HAZ microstructures with hot ductility properties of the alloy revealed that the temperature at which the alloy exhibited zero ductility during heating was within the temperature range at which grain boundary liquation was observed. The on-cooling ductility of the alloy was significantly damaged by the on-heating liquation reaction, as reflected by the considerably low ductility recovery temperature (DRT). Important characteristics of the intergranular liquid that could influence HAZ microfissuring of the alloy in overaged condition are also discussed.

  20. Is It a Cold or an Allergy? Symptoms Cold Airborne Allergy

    E-print Network

    Bandettini, Peter A.

    Is It a Cold or an Allergy? Symptoms Cold Airborne Allergy Cough Common Sometimes General Aches Decongestants Prevention Wash your hands often with soap and water Avoid close contact with anyone with a cold

  1. COLD-SAT dynamic model

    NASA Technical Reports Server (NTRS)

    Adams, Neil S.; Bollenbacher, Gary

    1992-01-01

    This report discusses the development and underlying mathematics of a rigid-body computer model of a proposed cryogenic on-orbit liquid depot storage, acquisition, and transfer spacecraft (COLD-SAT). This model, referred to in this report as the COLD-SAT dynamic model, consists of both a trajectory model and an attitudinal model. All disturbance forces and torques expected to be significant for the actual COLD-SAT spacecraft are modeled to the required degree of accuracy. Control and experimental thrusters are modeled, as well as fluid slosh. The model also computes microgravity disturbance accelerations at any specified point in the spacecraft. The model was developed by using the Boeing EASY5 dynamic analysis package and will run on Apollo, Cray, and other computing platforms.

  2. Commentary on ``Figuring Physics/Rapid Evaporation''

    NASA Astrophysics Data System (ADS)

    Bohren, Craig

    2007-11-01

    The Figuring Physics that appeared in our April 2007 issue has drawn a number of responses. The question posed by Paul Hewitt in that piece had to do with evaporative cooling: "Consider four grams of boiling water poured onto a cold surface. Suppose one gram rapidly evaporates by absorbing 540 calories from the remaining three grams of water, ideally with no other heat transfer occurring. The remaining three grams will become (a) water at a temperature above 0°C, (b) water at 0°C, or (c) ice at 0°C." Hewitt's answer (c) drew protests from readers who argued that this would violate the second law of thermodynamics.

  3. Rapidly solidified titanium alloys by melt overflow

    NASA Technical Reports Server (NTRS)

    Gaspar, Thomas A.; Bruce, Thomas J., Jr.; Hackman, Lloyd E.; Brasmer, Susan E.; Dantzig, Jonathan A.; Baeslack, William A., III

    1989-01-01

    A pilot plant scale furnace was designed and constructed for casting titanium alloy strips. The furnace combines plasma arc skull melting techniques with melt overflow rapid solidification technology. A mathematical model of the melting and casting process was developed. The furnace cast strip of a suitable length and width for use with honeycomb structures. Titanium alloys Ti-6Al-4V and Ti-14Al-21 Nb were successfully cast into strips. The strips were evaluated by optical metallography, microhardness measurements, chemical analysis, and cold rolling.

  4. The effect of prior cold-work on the deformation behaviour of neutron irradiated AISI 304 austenitic stainless steel

    NASA Astrophysics Data System (ADS)

    Karlsen, Wade; Van Dyck, Steven

    2010-11-01

    Cold-work is intentionally employed to increase the yield strength of austenitic stainless steels and also occurs during fabrication processes, but it has also been associated with greater incidence of stress corrosion cracking. This study examined the effect of up to 3.85 dpa neutron irradiation on the deformation behaviour and microstructures of 30% cold-worked AISI 304 material tensile tested at 300 °C. While the deformation behaviour of 0.07 dpa material was similar to non-irradiated material tested at the same temperature, its stress-strain curve was shifted upwards by about 200 MPa. Materials irradiated to over 2 dpa hardened some 400-500 MPa, but showed limited strain hardening capacity, exhibiting precipitous softening with further straining beyond the yield point. The observed behaviour is most likely a consequence of planar deformation products serving as strengtheners to the unirradiated bulk on the one hand, while promoting strain localization on the other, behaviour exacerbated by the subsequent neutron irradiation.

  5. Regulation of RNA Synthesis by DNA-Dependent RNA Polymerases and RNases during Cold Acclimation in Winter and Spring Wheat.

    PubMed

    Sarhan, F; Chevrier, N

    1985-06-01

    Chromatin DNA-dependent RNA polymerases and RNases activities were measured in winter and spring varieties to understand the overall regulation of RNA synthesis during cold acclimation. We found that total RNA polymerase activities were significantly higher in chromatin isolated from winter wheat compared to the spring wheat during the acclimation period. This increase was parallel to the increase in protein and RNA contents during hardening. The ratio of RNA polymerase I to RNA polymerase II activity was higher than 2 in winter wheat after 30 days of hardening compared, to a ratio of 0.90 under the nonhardening conditions. The increase in activity and the ratio of polymerase I to polymerase II was maintained after the separation of the enzymes from the template, suggesting that RNA synthesis is regulated in part at the enzyme level. On the other hand, the chromatin associated RNase activity decreased in both varieties during acclimation, indicating a nonspecific inhibition caused by low temperature rather than a selective genetic response associated with cold acclimation. PMID:16664225

  6. Dynamical phase interferometry of cold atoms in optical lattices

    NASA Astrophysics Data System (ADS)

    London, Uri; Gat, Omri

    2011-12-01

    We study the propagation of cold-atom wave packets in an interferometer with a Mach-Zehnder topology based on the dynamical phase of Bloch oscillation in a weakly forced optical lattice with a narrow potential barrier that functions as a cold-atom wave-packet splitter. We calculate analytically the atomic wave function, and show that the expected number of atoms in the two outputs of the interferometer oscillates rapidly as a function of the angle between the potential barrier and the forcing direction with period proportional to the external potential difference across a lattice spacing divided by the lattice band energy scale. The interferometer can be used as a high-precision force probe whose principle of operation is different from current interferometers based on the overall position of Bloch oscillating wave packets.

  7. Dynamical phase interferometry of cold atoms in optical lattices

    SciTech Connect

    London, Uri; Gat, Omri [Racah Institute of Physics, Hebrew University of Jerusalem, Jerusalem 91904 (Israel)

    2011-12-15

    We study the propagation of cold-atom wave packets in an interferometer with a Mach-Zehnder topology based on the dynamical phase of Bloch oscillation in a weakly forced optical lattice with a narrow potential barrier that functions as a cold-atom wave-packet splitter. We calculate analytically the atomic wave function, and show that the expected number of atoms in the two outputs of the interferometer oscillates rapidly as a function of the angle between the potential barrier and the forcing direction with period proportional to the external potential difference across a lattice spacing divided by the lattice band energy scale. The interferometer can be used as a high-precision force probe whose principle of operation is different from current interferometers based on the overall position of Bloch oscillating wave packets.

  8. EBSD characterization of twinning in cold-rolled CP-Ti

    SciTech Connect

    Li, X., E-mail: csulixu@hotmail.com [School of Materials Science and Engineering, Central South University, Changsha 410083 (China); Duan, Y.L., E-mail: 876270744@qq.com [School of Materials Science and Engineering, Central South University, Changsha 410083 (China); Xu, G.F., E-mail: csuxgf66@csu.edu.cn [School of Materials Science and Engineering, Central South University, Changsha 410083 (China); State Key Laboratory of Powder Metallurgy, Changsha 410083 (China); Peng, X.Y., E-mail: pxy0807@126.com [School of Materials Science and Engineering, Central South University, Changsha 410083 (China); Dai, C., E-mail: li-xu@nim.ac.cn [School of Materials Science and Engineering, Central South University, Changsha 410083 (China); Zhang, L.G., E-mail: 290571871@qq.com [Zunyi Titanium Industry Co. Ltd., Zunyi 563004 (China); Li, Z., E-mail: lizhou6931@mail.csu.edu.cn [School of Materials Science and Engineering, Central South University, Changsha 410083 (China)

    2013-10-15

    This work presents the use of a mechanical testing system and the electron backscatter diffraction technique to study the mechanical properties and twinning systems of cold-rolled commercial purity titanium, respectively. The dependence of twinning on the matrix orientation is analyzed by the distribution map of Schmid factor. The results showed that the commercial purity titanium experienced strong strain hardening and had excellent formability during rolling. Both the (112{sup ¯}2)<112{sup ¯}3{sup ¯}> compressive twins and (101{sup ¯}2)<101{sup ¯}1{sup ¯}> tensile twins were dependent on the matrix orientation. The Schmid factor of a grain influenced the activation of a particular twinning system. The specific rolling deformation of commercial purity titanium controlled the number and species of twinning systems and further changed the mechanical properties. - Highlights: • CP-Ti experienced strain hardening and had excellent formability. • Twins were dependent on the matrix orientation. • Schmid factor of a grain influenced the activation of a twinning system. • Rolling deformation controlled twinning systems and mechanical properties.

  9. Effect of Cold Rolling on as-ECAP Interstitial Free Steel

    NASA Astrophysics Data System (ADS)

    Hazra, Sujoy S.; Gazder, Azdiar A.; Carman, Andrew; Pereloma, Elena V.

    2011-05-01

    Ti-stabilized interstitial free steel subjected to eight passes, route BC room temperature equal channel angular pressing (ECAP) additionally was cold rolled (CR) up to 95 pct thickness reduction. Electron back-scattering diffraction and transmission electron microscopy characterized microstructural refinement and microtexture evolution, whereas the mechanical properties were assessed by uniaxial tensile tests. After 95 pct CR, the average high-angle grain boundary spacing reduces to 0.14 ?m, whereas the high-angle boundary fraction increases to ~81 pct. The ECAP negative simple shear texture components rotate by ~15 deg around the transverse direction toward the rolling direction for up to 50 pct CR, with typical rolling textures observed at 95 pct CR. The decrease in boundary spacing produces a ~500 MPa gain in 0.2 pct proof stress, a ~600 MPa increase in ultimate tensile strength (UTS), and a ~4 pct loss in total elongation after 95 pct CR. Similar rates of decrease in work hardening correspond to comparable rates of cross and/or multiple slip events irrespective of the processing regime and substructural refinement. The fracture mode of the tensile samples changes from ductile to brittle type between ECAP and 95 pct CR and is attributed to the reduced work hardening capacity of the latter. The modified Hall-Petch equation shows that the convergence of high-angle boundary spacing values with their low-angle counterparts results in an increased contribution via boundary strengthening to the 0.2 pct proof stress and UTS.

  10. The status of `cold fusion'

    Microsoft Academic Search

    David J. Nagel

    1998-01-01

    The questions raised by reports of nuclear reactions at low energies, so called `cold fusion', are not yet answered to the satisfaction of many scientists. Further experimental investigations of these and related questions seems desirable, at least for scientific if not practical reasons. Properly conducted, such investigations would be indistinguishable from normal research. They would yield information germane to accepted

  11. Bad cold for a butterfly?

    Microsoft Academic Search

    Wilte G. Zijlstra; Bas J. Zwaan; Paul M. Brakefield

    The tropical butterfly Bicyclus anynana can, in the dry season, encounter temperatures below 10°C or even lower at higher altitudes. We studied the cold resistance of several stages in the life cycle of this butterfly (egg, pupa, adult). Egg hatching declined at low temperatures, with no hatching at +6°C and reduced hatching at 12°C. Pupa could sustain almost two days

  12. Cold War Geopolitics: Embassy Locations.

    ERIC Educational Resources Information Center

    Vogeler, Ingolf

    1995-01-01

    Asserts that the geopolitics of the Cold War can be illustrated by the diplomatic ties among countries, particularly the superpowers and their respective allies. Describes a classroom project in which global patterns of embassy locations are examined and compared. Includes five maps and a chart indicating types of embassy locations. (CFR)

  13. Underwater cold tap machine tested

    SciTech Connect

    Not Available

    1985-05-01

    Tests are complete on a strategic cold tap machine for underwater lines. The system was designed around Total's Norway-UK Frigg gas line. It provides a permanent, easily mobilized, mechanical insurance against damage to the Frigg line but also provides a proven, workable principle for the repair or modification of other lines. The design of the system is discussed.

  14. The Cold Blooded Killer: Hypothermia.

    ERIC Educational Resources Information Center

    Keller, Rosanne

    Part of a series of home literacy readers with conversational text and sketches, this booklet depicts the subarctic Alaskan environment where cold makes extreme demands on body metabolism. Body temperature must be maintained above 80F (26.7C). A condition of too little body-heat is termed hypo- ('deficit') thermia ('heat'). Hypothermia is the…

  15. Advances in cold plasma technology

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Foodborne pathogens continue to be an issue on a variety of commodities, prompting research into novel interventions. Cold plasma is a nonthermal food processing technology which uses energetic, reactive gases to inactivate contaminating microbes on meats, poultry and fruits and vegetables. The prim...

  16. Interface Model of Cold Fusion

    Microsoft Academic Search

    Talbot A. Chubb

    The interface theory of cold fusion is a variant of Ion Band State (IBS) Theory.1 It models Bloch symmetry deuterons in a 2-dimensional metal lattice instead of the 3-dimensional metal lattice first used. Both IBS variants recognize that the required lattice symmetry has limited extent, with the reactive deuterons being bound inside a closed volume like a box. The reactive

  17. Hot, Cold, Fresh and Salty

    NSDL National Science Digital Library

    Jerry Roth

    In this activity, learners observe the effects of the layering of warm and cold water and water that is more or less saline than regular water. They will discover how the effects of salinity and temperature are the root cause of thermohaline layering in the ocean.

  18. Rapid Treatment of Rhinophyma with Powered Microdebrider

    PubMed Central

    Faris, C.; Manjaly, J. G.; Ismail-Koch, H.; Caldera, S.

    2013-01-01

    We describe here our experience in using sinus microdebrider to rapidly debulk and sculpt the tissues in cases of rhinophyma correction. We utilized the use of the 4?mm M4 Rotatable Cutting Straight Sinus Blade on a straight Straightshot M4 Microdebrider by Medtronic at 800 rpm oscillation which is normally utilised in our sinus surgery practice. The microdebrider is straightforward to use and is already stocked in most ENT departments. It requires no additional training or cost outlay for departments that perform endoscopic sinus surgery with microdebrider. In our experience it affords the surgeon the ability to rapidly and accurately sculpt the nose to an excellent aesthetic result. We feel it is a more precise tool than cold steel or Bovie cautery, quicker than CO2 laser techniques, and avoids the aerosol of dermabrasion. No complications occurred in our series, and all patients rated their cosmetic outcome as good to excellent. PMID:23509654

  19. Rapid treatment of rhinophyma with powered microdebrider.

    PubMed

    Faris, C; Manjaly, J G; Ismail-Koch, H; Caldera, S

    2013-01-01

    We describe here our experience in using sinus microdebrider to rapidly debulk and sculpt the tissues in cases of rhinophyma correction. We utilized the use of the 4?mm M4 Rotatable Cutting Straight Sinus Blade on a straight Straightshot M4 Microdebrider by Medtronic at 800 rpm oscillation which is normally utilised in our sinus surgery practice. The microdebrider is straightforward to use and is already stocked in most ENT departments. It requires no additional training or cost outlay for departments that perform endoscopic sinus surgery with microdebrider. In our experience it affords the surgeon the ability to rapidly and accurately sculpt the nose to an excellent aesthetic result. We feel it is a more precise tool than cold steel or Bovie cautery, quicker than CO2 laser techniques, and avoids the aerosol of dermabrasion. No complications occurred in our series, and all patients rated their cosmetic outcome as good to excellent. PMID:23509654

  20. Nonthermal electron-positron pairs and cold matter in the central engines of active galactic nuclei

    NASA Technical Reports Server (NTRS)

    Zdziarski, Andrzej A.

    1992-01-01

    The nonthermal e(+/-) pair model of the central engine of active galactic nuclei (AGNs) is discussed. The model assumes that nonthermal e(+/-) pairs are accelerated to highly relativistic energies in a compact region close to the central black hole and in the vicinity of some cold matter. The model has a small number of free parameters and explains a large body of AGN observations from EUV to soft gamma-rays. In particular, the model explains the existence of the UV bump, the soft X-rays excess, the canonical hard X-ray power law, the spectral hardening above about 10 keV, and some of the variability patterns in the soft and hard X-rays. In addition, the model explains the spectral steepening above about 50 keV seen in NGC 4151.