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1

Induction apparatus for vacuum annealing of tubular parts  

Microsoft Academic Search

the tubes are etched in3-12% HzSO 4 at 70-90 °. We have developed an apparatus for final recrystallizatio n vacuum annealing of tubular products with a bottom made of L80 brass. The tubes are producedby cold drawing with intermediate annealingand are used in manufacturing bellows of incubators with hydraulic corrugation. The diameter of the tubes after drawing and before final

N. K. Mochalin; Z. K. Zastol'skaya; L. A. Lisitskaya

1978-01-01

2

Inverse temperature and annealing phenomena during degradation of crosslinked polyolefins  

Microsoft Academic Search

The radiation-thermal degradation of several types of commercial cable insulation materials (semi-crystalline crosslinked polyolefins) was investigated as a function of temperature in the range of 22–120 °C. Mechanical property deterioration surprisingly occurred most rapidly at the lowest temperatures. This unusual phenomenon was corroborated by fundamental differences in the degradation mechanism at elevated and ambient temperatures. Annealing at elevated temperatures of

M. Celina; K. T. Gillen; R. L. Clough

1998-01-01

3

Nucleation phenomena in an annealed damage model: Statistics of times to failure  

NASA Astrophysics Data System (ADS)

In this paper we investigate the statistical behavior of an annealed continuous damage model. For different model variations we study distributions of times to failure and compare these results with the classical case of metastable nucleation in statistical physics. We show that our model has a tuning parameter, related to the degree of damage reversibility, that determines the model's behavior. Depending on the value of this parameter, our model exhibits statistical behavior either similar to classical reversible nucleation phenomena in statistical physics or to an absolutely different type of behavior intrinsic to systems with damage. This comparison allows us to investigate possible similarities and differences between damage phenomena and reversible nucleation.

Abaimov, S. G.; Cusumano, J. P.

2014-12-01

4

Tribological behavior of RF sputtering WS2 thin films with vacuum annealing  

NASA Astrophysics Data System (ADS)

Thin films of tungsten disulfide (WS2) were deposited on 3Cr13 martensitic stain less steel substrate by RF sputtering. The as-deposited films were annealed at 200,400 and 600 °C for 2 h in vacuum. The vacuum degree was 510-4 Pa. Composition, surface morphology, structure properties and tribological behavior were studied by EDS, SEM, X-ray diffraction techniques and tribometer, respectively. At 200 °C, the films showed low crystallization structure and the tribological behavior was not improved obviously. But at 400 °C, the films tribological behavior were improved obviously and non-crystalline to hexagonal structural transition appeared. When annealing temperature rose to 600 °C, the films were desquamated from substrate. The results suggested that suitable vacuum annealing was able to promote crystallization and improve tribological performance of RF sputtering WS2 films.

Guangyu, Du; Dechun, Ba; Zhen, Tan; Kun, Liu

5

Regulate the content of magnesium in Mg x Zn 1? x O films by vacuum anneal  

Microsoft Academic Search

MgxZn1?xO thin films were grown on c-sapphire substrates by metal-organic chemical vapor deposition (MOCVD), followed by annealing in vacuum at different temperatures for 1h. The UV emission peak was blue shifted in the photoluminescence (PL) spectra and a dramatic shift of (002) diffraction peak to higher angle was observed in X-ray diffraction (XRD) pattern with increasing anneal temperature. This suggested

Xin Dong; Huichao Zhu; Baolin Zhang; Weifeng Liu; Xiangping Li; Tianpeng Yang; Guotong Du

2008-01-01

6

Development of fast heating electron beam annealing setup for ultra high vacuum chamber  

SciTech Connect

We report the design and development of a simple, electrically low powered and fast heating versatile electron beam annealing setup (up to 1000?°C) working with ultra high vacuum (UHV) chamber for annealing thin films and multilayer structures. The important features of the system are constant temperature control in UHV conditions for the temperature range from room temperature to 1000?ºC with sufficient power of 330 W, at constant vacuum during annealing treatment. It takes approximately 6 min to reach 1000?°C from room temperature (?10{sup ?6} mbar) and 45 min to cool down without any extra cooling. The annealing setup consists of a UHV chamber, sample holder, heating arrangement mounted on suitable UHV electrical feed-through and electronic control and feedback systems to control the temperature within ±1?ºC of set value. The outside of the vacuum chamber is cooled by cold air of 20?°C of air conditioning machine used for the laboratory, so that chamber temperature does not go beyond 50?°C when target temperature is maximum. The probability of surface oxidation or surface contamination during annealing is examined by means of x-ray photoelectron spectroscopy of virgin Cu sample annealed at 1000?°C.

Das, Sadhan Chandra [UGC-DAE Consortium For Scientific Research, University Campus, Khandwa Road, Indore 452 001, MP (India) [UGC-DAE Consortium For Scientific Research, University Campus, Khandwa Road, Indore 452 001, MP (India); School of Electronics, Devi Ahilya University, Indore 452001, MP (India); Institute of Physics, University of Greifswald, Felix Hausdroff Str. 6 (Germany); Majumdar, Abhijit, E-mail: majuabhijit@gmail.com, E-mail: majumdar@uni-greifswald.de; Hippler, R. [Institute of Physics, University of Greifswald, Felix Hausdroff Str. 6 (Germany)] [Institute of Physics, University of Greifswald, Felix Hausdroff Str. 6 (Germany); Katiyal, Sumant [School of Electronics, Devi Ahilya University, Indore 452001, MP (India)] [School of Electronics, Devi Ahilya University, Indore 452001, MP (India); Shripathi, T. [UGC-DAE Consortium For Scientific Research, University Campus, Khandwa Road, Indore 452 001, MP (India)] [UGC-DAE Consortium For Scientific Research, University Campus, Khandwa Road, Indore 452 001, MP (India)

2014-02-15

7

Development of fast heating electron beam annealing setup for ultra high vacuum chamber.  

PubMed

We report the design and development of a simple, electrically low powered and fast heating versatile electron beam annealing setup (up to 1000?°C) working with ultra high vacuum (UHV) chamber for annealing thin films and multilayer structures. The important features of the system are constant temperature control in UHV conditions for the temperature range from room temperature to 1000?ºC with sufficient power of 330 W, at constant vacuum during annealing treatment. It takes approximately 6 min to reach 1000?°C from room temperature (?10(-6) mbar) and 45 min to cool down without any extra cooling. The annealing setup consists of a UHV chamber, sample holder, heating arrangement mounted on suitable UHV electrical feed-through and electronic control and feedback systems to control the temperature within ±1?ºC of set value. The outside of the vacuum chamber is cooled by cold air of 20?°C of air conditioning machine used for the laboratory, so that chamber temperature does not go beyond 50?°C when target temperature is maximum. The probability of surface oxidation or surface contamination during annealing is examined by means of x-ray photoelectron spectroscopy of virgin Cu sample annealed at 1000?°C. PMID:24593396

Das, Sadhan Chandra; Majumdar, Abhijit; Katiyal, Sumant; Shripathi, T; Hippler, R

2014-02-01

8

Vacuum chamber surface electronic properties influencing electron cloud phenomena  

NASA Astrophysics Data System (ADS)

In the vacuum science community, it is now commonly accepted that, for the present and next generation of accelerators, the surface electronic properties of the vacuum chamber material have to be studied in detail. Moreover, such studies are of valuable help to define the cleaning procedures of the chosen materials and to identify the most efficient vacuum commissioning. In the case of the large hadron collider (LHC) the proton beam stability, in the presence of an electron cloud, is analysed using beam induced electron multipacting (BIEM) simulations requiring a number of surface related properties, such as photon reflectivity, electron and photon induced electron emission, heat load, etc. and their modification during machine commissioning and operation. Such simulation codes base their validity on the completeness and reliability of the aforementioned input data. In this work we describe how a surface science approach has been applied to measure, total electron yield (SEY) as well as energy distribution curves excited by a very low-energy electron beam (0-320 eV), from the industrially prepared Cu co-laminated material, the adopted LHC beam-screen material, held at cryogenic temperatures (about 9 K). The data show that the SEY converges to unity at zero primary electron energy and that the ratio of reflected to secondary electrons increases for decreasing energy below about 70 eV, and becomes dominant below electron energies of about 20 eV. These observations lead to the notion of long-lived low-energy electrons in the accelerator vacuum chamber, which could be an issue for the LHC, damping rings and future accelerators.

Cimino, R.; Collins, I. R.

2004-07-01

9

A nonreciprocal racetrack resonator based on vacuum-annealed magnetooptical cerium-substituted yttrium iron garnet.  

PubMed

Vacuum annealed polycrystalline cerium substituted yttrium iron garnet (CeYIG) films deposited by radio frequency magnetron sputtering on non-garnet substrates were used in nonreciprocal racetrack resonators. CeYIG annealed at 800°C for 30 min provided a large Faraday rotation angle, close to the single crystal value. Crystallinity, magnetic properties, refractive indices and absorption coefficients were measured. The resonant transmission peak of the racetrack resonator covered with CeYIG was non-reciprocally shifted by applying an in-plane magnetic field. PMID:25320991

Goto, Taichi; Onbasli, Mehmet C; Kim, Dong Hun; Singh, Vivek; Inoue, M; Kimerling, Lionel C; Ross, C A

2014-08-11

10

Laser-plasma simulations of astrophysical phenomena and novel applications to semiconductor annealing  

NASA Astrophysics Data System (ADS)

At the frontier of plasma physics and technology are applications of laser-generated plasmas to laboratory simulations of astrophysical phenomena and to industrial processing. This article presents work at the Naval Research Laboratory in both of these areas. We show how laser plasmas are used to measure a blast wave corrugation overstability important in astrophysics. Detailed atomic physics calculations of radiative cooling within the blast front are used to develop a criterion of the existence of the overstability and are used to explain the experimental results. The criterion depends on quantities such as element abundances, densities, temperatures, and blast wave velocities—quantities which can be measured spectroscopically—and therefore used to infer whether astrophysical blast wave nonuniformities are the result of this instability. In other experiments, high-velocity jets are formed in the laboratory using miniature hollow cones. Jets produced by these cones are used to study the physics of jets occurring in supernovae and in star-forming accretion disks. In industrial semiconductor processing, annealing, that is, removing crystal damage and electrically activating the semiconductor, is a critical step. Industrial annealing techniques most often utilize heat generated by an oven, flash lamps, or a low-power laser. During such heating dopants within the semiconductor lattice diffuse and spread. This degrades the performance of circuits in which the individual circuit elements are very close to each other. We are developing an annealing technique in which shock or sound waves generated by a laser plasma are used to anneal the semiconductor. We have demonstrated that the method works over small areas and that it does not lead to significant dopant diffusion.

Grun, J.; Laming, M.; Manka, C.; Donnelly, D. W.; Covington, B. C.; Fischer, R. P.; Velikovich, A.; Khokhlov, A.

2003-10-01

11

Photocatalytic activity of high-vacuum annealed CdS–TiO 2 thin film  

Microsoft Academic Search

CdS–TiO2 thin film heterojunctions were prepared on glass and indium tin oxide (ITO) substrates with the aim of improving photocatalytic efficiency both in UV–visible and visible light irradiation. The CdS under-layers were prepared by chemical bath deposition technique and subsequently they were annealed in the high vacuum of 5×10?5 Pa at the temperature of 400 °C. The structural and optical

S. Biswas; M. F. Hossain; T. Takahashi; Y. Kubota; A. Fujishima

2008-01-01

12

High-vacuum annealing reduction of Co/CoO nanoparticles  

NASA Astrophysics Data System (ADS)

Porous films of Co/CoO magnetic nanoparticles have been obtained by inert gas condensation and partially oxidized in situ in the deposition chamber. These nanoparticle films were subjected to thermal treatments in high vacuum and the chemical and structural changes monitored by x-ray diffraction, transmission electron microscopy, transport and magnetic measurements (with a focus on the exchange-bias phenomenon), which evidence that for vacuum annealing temperatures above 360?°C, most of the CoO phase is reduced to metallic Co without requiring the presence of an external reducing agent (e.g., H2) or a plasma. Additionally, there is a certain degree of particle coalescence resulting in the formation of greater nanoparticles as the annealing temperature increases. This yields a smaller proportion of CoO compared to metallic Co and a reduction of the Co/CoO interface density, pinpointed by a drastic decrease of the exchange-bias field. The crucial roles of the vacuum level and the surface-to-volume ratio are evidenced by magnetic measurements, highlighting the potential of magnetometry as a probe for the reduction/oxidation of composite nanostructures.

López Antón, R.; González, J. A.; Andrés, J. P.; Canales-Vázquez, J.; De Toro, J. A.; Riveiro, J. M.

2014-03-01

13

Impact of vacuum anneal at low temperature on Al2O3/In-based III-V interfaces  

NASA Astrophysics Data System (ADS)

We report on the effect of vacuum anneal on interfacial oxides formed between Al2O3 and III-V semiconductors. On InGaAs, no interfacial oxide is detected after annealing at 600 °C under UHV whereas annealing under secondary vacuum favours the regrowth of thin InGaOx interfacial oxide. Lowering the temperature at 400 °C highlights the effect of III-V substrates since In-OH bonds are only formed on InAs by OH release from TMA/H2O deposited alumina. On InGaAs, regrowth of InGaOx is observed, as a result of preferential oxidation of Ga. On InP, a transition from InPOx to POx is highlighted.

Martinez, E.; Grampeix, H.; Desplats, O.; Herrera-Gomez, A.; Ceballos-Sanchez, O.; Guerrero, J.; Yckache, K.; Martin, F.

2012-06-01

14

Auger electron spectroscopy and electron loss spectroscopy comparative study of vacuum annealing effects on InP surface  

NASA Astrophysics Data System (ADS)

Auger electron spectroscopy (AES) and electron loss spectroscopy (ELS) have been performed in order to investigate vacuum annealing effects on InP surface. Both techniques appeared suitable for detecting indium clustering induced by thermal surface decomposition through InM4.5N4.5N4.5 spectrum modifications (AES) and In plasmon excitation (ELS). The formation of In microinclusions at the surface is detected by the two techniques for annealing temperature of 460±30 °C. In addition, AES shows that phosphorus has a complex behavior near the surface involving diffusion from the bulk, surface segregation, and desorption. These competitive mechanisms are shown to result in phosphorus enrichment or depletion of the surface layer depending mainly on the annealing temperature.

Massies, J.; Lemaire-Dezaly, F.

1985-01-01

15

Study of the I-V characteristics of nanostructured Pd films on a Si substrate after vacuum annealing  

SciTech Connect

The I-V characteristics of nanostructured Pd films on a Si substrate are investigated. The nanostructures (nanoislands) are formed by the vacuum annealing of continuous ultrathin Pd films sputtered onto a substrate. The shape of the I-V characteristics of the investigated Si substrate-Pd film system is shown to be heavily dependent on the degree of film nanostructuring. The surface morphology of the films is studied using scanning electron microscopy.

Tomilin, S. V., E-mail: tomilin_znu@mail.ru; Yanovsky, A. S.; Tomilina, O. A.; Mikaelyan, G. R. [Zaporozhye National University, Department of Semiconductor Physics (Ukraine)

2013-06-15

16

Phase Formation and Superconductivity of Fe-TUBE Encapsulated and Vacuum-Annealed MgB2  

NASA Astrophysics Data System (ADS)

We report optimization of the synthesis parameters viz. heating temperature (TH), and hold time (thold) for vacuum-annealed (10-5 Torr) and LN2 (liquid nitrogen) quenched MgB2 compound. These are single-phase compounds crystallizing in the hexagonal structure (space group P6/mmm) at room temperature. Our XRD results indicated that for phase-pure MgB2, the TH for 10-5 Torr annealed and LN2-quenched samples is 750°C. The right stoichiometry i.e., MgB2 of the compound corresponding to 10-5 Torr and TH of 750°C is found for the hold time (thold) of 2.30 hours. With varying thold from 1-4 hours at fixed TH (750°C) and vacuum (10-5 Torr), the c-lattice parameter decreases first and later increases with thold (hours) before a near saturation, while the a-lattice parameter first increases and later decreases beyond a thold of 2.30 hours. The c/a ratio versus thold plot showed an inverted bell-shaped curve, touching the lowest value of 1.141, which is the reported value for perfect stoichiometry of MgB2. The optimized stoichimetric MgB2 compound exhibited superconductivity at 39.2 K with a transition width of 0.6 K. In conclusion, the synthesis parameters for phase pure stoichimetric vacuum-annealed MgB2 compound are optimized and are compared with widely-reported Ta tube encapsulated samples.

Singh, K. P.; Awana, V. P. S.; Shahabuddin, Md.; Husain, M.; Saxena, R. B.; Nigam, Rashmi; Ansari, M. A.; Gupta, Anurag; Narayan, Himanshu; Halder, S. K.; Kishan, H.

17

Vacuum annealed cerium-substituted yttrium iron garnet films on non-garnet substrates for integrated optical circuits  

SciTech Connect

Polycrystalline cerium-substituted yttrium iron garnet (CeYIG) showing large Faraday rotation (FR) in the near-IR region was grown on non-garnet (synthetic fused silica, Si, and Si-on-insulator) substrates by sputtering followed by thermal annealing in vacuum. The FR of the films is comparable to the single crystal value. Structural characterization, magnetic properties, refractive index, extinction coefficient, surface topography, and FR vs. wavelength were measured and the magnetooptical figure of merit was compared with that of CeYIG films on garnet substrates.

Goto, Taichi; Ross, C. A. [Massachusetts Institute of Technology, 77 Massachusetts Avenue, Cambridge, Massachusetts 02139 (United States); Eto, Yu; Kobayashi, Keiichi; Haga, Yoji; Inoue, Mitsuteru [Toyohashi University of Technology, Hibarigaoka, Tempaku, Toyohashi, Aichi 441-8580 (Japan)

2013-05-07

18

Effect of thermal annealing in vacuum on the photovoltaic properties of electrodeposited Cu2O-absorber solar cell  

NASA Astrophysics Data System (ADS)

Heterojunction solar cells were fabricated by electrochemical deposition of p-type, cuprous oxide (Cu2O) absorber on sputtered, n-type ZnO layer. X-ray diffraction measurements revealed that the as-deposited absorber consists mainly of Cu2O, but appreciable amounts of metallic Cu and cupric oxide (CuO) are also present. These undesired oxidation states are incorporated during the deposition process and have a detrimental effect on the photovoltaic properties of the cells. The open circuit voltage (VOC), short circuit current density (jSC), fill factor (FF) and power conversion efficiency (?) of the as-deposited cells are 0.37 V, 3.71 mA/cm2, 35.7% and 0.49%, respectively, under AM1.5G illumination. We show that by thermal annealing in vacuum, at temperatures up to 300 °C, compositional purity of the Cu2O absorber could be obtained. A general improvement of the heterojunction and bulk materials quality is observed, reflected upon the smallest influence of the shunt and series resistance on the transport properties of the cells in dark and under illumination. Independent of the annealing temperature, transport is dominated by the space-charge layer generation-recombination current. After annealing at 300 °C the solar cell parameters could be significantly improved to the values of: VOC = 0.505 V, jSC = 4.67 mA/cm2, FF = 47.1% and ? = 1.12%.

Dimopoulos, T.; Pei?, A.; Abermann, S.; Postl, M.; List-Kratochvil, E. J. W.; Resel, R.

2014-07-01

19

The expansion of a plasma into a vacuum - Basic phenomena and processes and applications to space plasma physics  

NASA Technical Reports Server (NTRS)

In this review attention is called to basic phenomena and physical processes involved in the expansion of a plasma into a vacuum, or the expansion of a plasma into a more tenuous plasma, in particular the fact that upon the expansion, ions are accelerated and reach energies well above their thermal energy. Also, in the process of the expansion a rarefaction wave propagates into the ambient plasma, an ion front moves into the expansion volume, and discontinuities in plasma parameters occur. The physical processes which cause the above phenomena are discussed, and their possible application is suggested for the case of the distribution of ions and electrons (hence plasma potential and electric fields) in the wake region behind artificial and natural obstacles moving supersonically in a rarefied space plasma. To illustrate this, some in situ results are reexamined. Directions for future work in this area via the utilization of the Space Shuttle and laboratory work are also mentioned.

Wright, K. H., Jr.; Stone, N. H.; Samir, U.

1983-01-01

20

Effects of substrate heating and vacuum annealing on optical and electrical properties of alumina-doped ZnO films deposited by DC magnetron sputtering  

NASA Astrophysics Data System (ADS)

Alumina-doped zinc oxide (AZO) films have wide range of applications in optical and optoelectronic devices. AZO films have advantage in high transparency, high stability to hydrogen plasma and low cost to alternative ITO film. AZO film was prepared by direct-current (DC) magnetron sputtering from ceramic ZnO:Al2O3 target. The AZO films were compared in two different conditions. The first is substrate heating process, in which AZO film was deposited by different substrate temperature, room temperature, 150 °C and 250 °C. The second is vacuum annealing process, in which AZO film with deposited at room temperature have been annealed at 250 °C and 450 °C in vacuum. The optical properties, electrical properties, grain size and surface structure properties of the films were studied by UV-VIS-NIR spectrophotometer, Hall effect measurement equipment, x-ray diffraction, and scanning electron microscopy. The resistivity, carrier mobility, carrier concentration, and grain size of AZO films were 1.92×10-3 ?-cm, 6.38 cm2/Vs, 5.08×1020 #/cm3, and 31.48 nm respectively, in vacuum annealing of 450 °C. The resistivity, carrier mobility, carrier concentration, and grain size of AZO films were 8.72×10-4 ?-cm, 6.32 cm2/Vs, 1.13×1021 #/cm3, and 31.56 nm, respectively, when substrate temperature was at 250 °C. Substrate heating process is better than vacuum annealed process for AZO film deposited by DC Magnetron Sputtering.

Tang, Chien-Jen; Wang, Chun-Yuan; Jaing, Cheng-Chung

2011-10-01

21

Effect of non-vacuum thermal annealing on high indium content InGaN films deposited by pulsed laser deposition.  

PubMed

InGaN films with 33% and 60% indium contents were deposited by pulsed laser deposition (PLD) at a low growth temperature of 300 °C. The films were then annealed at 500-800 °C in the non-vacuum furnace for 15 min with an addition of N(2) atmosphere. X-ray diffraction results indicate that the indium contents in these two films were raised to 41% and 63%, respectively, after annealing in furnace. In(2)O(3) phase was formed on InGaN surface during the annealing process, which can be clearly observed by the measurements of auger electron spectroscopy, transmission electron microscopy and x-ray photoelectron spectroscopy. Due to the obstruction of indium out-diffusion by forming In(2)O(3) on surface, it leads to the efficient increment in indium content of InGaN layer. In addition, the surface roughness was greatly improved by removing In(2)O(3) with the etching treatment in HCl solution. Micro-photoluminescence measurement was performed to analyze the emission property of InGaN layer. For the as-grown InGaN with 33% indium content, the emission wavelength was gradually shifted from 552 to 618 nm with increasing the annealing temperature to 800 °C. It reveals the InGaN films have high potential in optoelectronic applications. PMID:23546117

Wang, Tzu-Yu; Ou, Sin-Liang; Shen, Kun-Ching; Wuu, Dong-Sing

2013-03-25

22

The effects of vacuum annealing on the top-most layer of 6H-SiC measured by Positron annihilation induced Auger Spectroscopy  

NASA Astrophysics Data System (ADS)

Silicon Carbide (SiC) in monocrystalline, hexagonal polytype form is a very interesting material for a wide class of novel application in electronics. The wide range of the band gap offered by different polytype with very little lattice mismatch can be utilized to grow smooth heterojunctions. Till now it has not been achieved and hence the surface characterization of such crystals is critical. Positron Annihilation induced Auger Electron Spectroscopy (PAES) is an established tool to characterize the top most atomic surface layer of solids. Here, PAES has been used to study the surface of 6H- SiC after annealing under different thermal and ambient conditions. The PAES measurements indicate that top-most atomic layer becomes C rich after vacuum annealing at 800 C. In additional a large chemical shift in the Si peak of approximately -12 eV was observed with PAES.

Mukherjee, S.; Nadesalingam, M.; Davis, B.; Brauer, G.; Weiss, A. H.

2007-03-01

23

Vacuum-Assisted Thermal Annealing of CH3NH3PbI3 for Highly Stable and Efficient Perovskite Solar Cells.  

PubMed

Solar cells incorporating lead halide-based perovskite absorbers can exhibit impressive power conversion efficiencies (PCEs), recently surpassing 15%. Despite rapid developments, achieving precise control over the morphologies of the perovskite films (minimizing pore formation) and enhanced stability and reproducibility of the devices remain challenging, both of which are necessary for further advancements. Here we demonstrate vacuum-assisted thermal annealing as an effective means for controlling the composition and morphology of the CH3NH3PbI3 films formed from the precursors of PbCl2 and CH3NH3I. We identify the critical role played by the byproduct of CH3NH3Cl on the formation and the photovoltaic performance of the perovskite film. By completely removing the byproduct through our vacuum-assisted thermal annealing approach, we are able to produce pure, pore-free planar CH3NH3PbI3 films with high PCE reaching 14.5% in solar cell device. Importantly, the removal of CH3NH3Cl significantly improves the device stability and reproducibility with a standard deviation of only 0.92% in PCE as well as strongly reducing the photocurrent hysteresis. PMID:25549113

Xie, Feng Xian; Zhang, Di; Su, Huimin; Ren, Xingang; Wong, Kam Sing; Grätzel, Michael; Choy, Wallace C H

2015-01-27

24

Characterization of mixed titanium-niobium oxide Ti2Nb10O29 annealed in vacuum as anode material for lithium-ion battery  

NASA Astrophysics Data System (ADS)

In this paper, the properties of mixed titanium-niobium oxide Ti2Nb10O29 (TNO) annealed in air and vacuum as anode material for lithium-ion battery were investigated. The color of TNO annealed in vacuum (V-TNO) is dark blue while white for TNO annealed in air (A-TNO). Moreover, lattice parameters for V-TNO were confirmed to be slightly larger than those for A-TNO. Introduction of oxygen defect in V-TNO was confirmed by thermogravimetric analysis. X-ray photoelectron spectroscopy analysis also indicated that Ti4+ in V-TNO are partially reduced into Ti3+, due to the introduction of oxygen defect in V-TNO. Electronic conductivity at room temperature for uni-axially pressed V-TNO powder is estimated to be around 10-6-10-5 S cm-1, which is more than three digits higher than that for pressed A-TNO powder (= 10-9 S cm-1). The enhancement of intrinsic electronic conductivity of TNO greatly contributes for improving the rate performance. At low current density of 0.5 mA cm-2, both A-TNO and V-TNO showed reversible capacity around 250 mAh g-1 at potential range from 1.0 to 2.5 V vs. Li/Li+, while at higher current density of 10 mA cm-2, V-TNO maintained much higher discharge capacity of 150 mAh g-1 than that for TNO (= 50 mAh g-1).

Takashima, Toshiki; Tojo, Tomohiro; Inada, Ryoji; Sakurai, Yoji

2015-02-01

25

Characteristics of Al-doped ZnO thin films prepared in Ar + H{sub 2} atmosphere and their vacuum annealing behavior  

SciTech Connect

The microstructure and electrical–optical properties of Al-doped ZnO (AZO) films have been studied as a function of H{sub 2} flux in the magnetron sputtering process at 150 °C and postannealing temperature in vacuum. As H{sub 2} flux increases in the sputtering gas, the AZO films deposited have a (002) preferred orientation rather than the mixed (100) and (002) orientations, the grain size shows a tendency to first increase then decrease, and (002) diffraction peak position is inclined to shift to higher angles first then to lower angles. The resistivity of the films first decreases then increases with H{sub 2} flux, and the lowest resistivity of 4.02 × 10{sup ?4}? cm is obtained at a H{sub 2} flux of 10 sccm. The average transmittance in the visible region shows little dependence on H{sub 2} flux. As a whole, the AZO films with higher values of figure of merit are obtained when the H{sub 2} flux is in the range of 6–12 sccm. The AZO films deposited in Ar and Ar + H{sub 2} exhibit different annealing behaviors. For the AZO film deposited in Ar, the grain size gradually increases, the stresses are relaxed, the resistivity first decreases then increases, and the average transmittance in the visible region is unchanged initially then somewhat decreased as annealing temperature is increased. The optimum annealing temperature for improving properties of AZO films deposited in Ar is 300 °C. For the AZO films deposited in Ar + H{sub 2}, annealing does not significantly change the microstructure but increases the resistivity of the films; the average transmittance in the visible region remains unchanged initially but greatly reduced with further increase in annealing temperature. The carrier transport in the as-deposited and annealed films appears to be controlled by a mechanism of grain boundary scattering, and the value of E{sub g} increases with the increase in carrier concentration due to Burstein–Moss effect.

Zhu, Bailin; Lü, Kun; Wang, Jun; Li, Taotao; Wu, Jun [Key Laboratory for Ferrous Metallurgy and Resources Utilization of Ministry of Education, Wuhan University of Science and Technology, Wuhan 430081 (China)] [Key Laboratory for Ferrous Metallurgy and Resources Utilization of Ministry of Education, Wuhan University of Science and Technology, Wuhan 430081 (China); Zeng, Dawen; Xie, Changsheng [Department of Materials Science and Engineering, Huazhong University of Science and Technology, Wuhan 430074 (China)] [Department of Materials Science and Engineering, Huazhong University of Science and Technology, Wuhan 430074 (China)

2013-11-15

26

Effect of annealing on the structural, optical and electrical properties of ITO films by RF sputtering under low vacuum level  

Microsoft Academic Search

Indium tin oxide (ITO) thin films were prepared by RF sputtering of ceramic ITO target in pure argon atmosphere at a high base pressure of 3×10?4mbar without substrate heating and oxygen admittance. The use of pure argon during deposition resulted in films with high transparency (80–85%) in the visible and IR wavelength region. The films were subsequently annealed in air

T. S. Sathiaraj

2008-01-01

27

CROSS-DISCIPLINARY PHYSICS AND RELATED AREAS OF SCIENCE AND TECHNOLOGY: Vacuum relaxation and annealing-induced enhancement of mobility of regioregular poly (3-hexylthiophene) field-effect transistors  

NASA Astrophysics Data System (ADS)

In order to enhance the performance of regioregular poly(3-hexylthiophene) (RR-P3HT) field-effect transistors (FETs), RR-P3HT FETs are prepared by the spin-coating method followed by vacuum placement and annealing. This paper reports that the crystal structure, the molecule interconnection, the surface morphology, and the charge carrier mobility of RR-P3HT films are affected by vacuum relaxation and annealing. The results reveal that the field-effect mobility of RR-P3HT FETs can reach 4.17 × 10-2 m2/(V · s) by vacuum relaxation at room temperature due to an enhanced local self-organization. Furthermore, it reports that an appropriate annealing temperature can facilitate the crystal structure, the orientation and the interconnection of polymer molecules. These results show that the field-effect mobility of device annealed at 150 °C for 10 minutes in vacuum at atmosphere and followed by placement for 20 hours in vacuum at room temperature is enhanced dramatically to 9.00 × 10-2 cm2/(V · s).

Tian, Xue-Yan; Xu, Zheng; Zhao, Su-Ling; Zhang, Fu-Jun; Xu, Xu-Rong; Yuan, Guang-Cai; Li, Jing; Sun, Qin-Jun; Wang, Ying

2009-11-01

28

Effects of HCl treatment and predeposition vacuum annealing on Al2O3/GaSb/GaAs metal–oxide–semiconductor structures  

NASA Astrophysics Data System (ADS)

The effects of HCl treatment and predeposition vacuum annealing (VA) on n-type GaSb/GaAs metal–oxide–semiconductor (MOS) structures with the atomic layer deposition (ALD) of Al2O3 dielectrics are studied. We obtained MOS structures with good Fermi level modulation by HCl treatment prior to the deposition of Al2O3. From X-ray photoelectron spectroscopy (XPS) analysis, we found that the Ga2O3 content increases during the Al2O3 deposition, whereas the amounts of Sb components are reduced. The excess growth of Ga2O3 is inhibited by the reductions in the amounts of Sb components by the HCl treatment. Further reductions in the amounts of Sb components are observed following predeposition VA, indicating a lower density of states (Dit). However, the frequency dispersion in the capacitance–voltage (C–V) characteristics increases with predeposition VA at higher temperatures.

Gotow, Takahiro; Fujikawa, Sachie; Fujishiro, Hiroki I.; Ogura, Mutsuo; Yasuda, Tetsuji; Maeda, Tatsuro

2015-02-01

29

Compositional study of vacuum annealed Al doped ZnO thin films obtained by RF magnetron sputtering  

SciTech Connect

Aluminum doped zinc oxide (AZO) thin films were obtained by RF magnetron sputtering. The effects of deposition parameters such as power, gas flow conditions, and substrate heating have been studied. Deposited and annealed films were characterized for composition as well as microstructure using x ray photoelectron spectroscopy and x ray diffraction. Films produced were polycrystalline in nature. Surface imaging and roughness studies were carried out using SEM and AFM, respectively. Columnar grain growth was predominantly observed. Optical and electrical properties were evaluated for transparent conducting oxide applications. Processing conditions were optimized to obtain highly transparent AZO films with a low resistivity value of 6.67 x 10{sup -4}{Omega} cm.

Shantheyanda, B. P.; Todi, V. O.; Sundaram, K. B.; Vijayakumar, A.; Oladeji, I. [Department of Electrical Engineering and Computer Science, University of Central Florida, Orlando, Florida 32816 (United States); Planar Energy Inc., 653 W. Michigan St., Orlando, Florida 32805 (United States)

2011-09-15

30

Effect of annealing under vacuum and in nitrogen atmosphere on the structure and strength of porous silicon nitride materials  

Microsoft Academic Search

This paper deals with a study of the structure and the temperature dependence of the strength of the porous silicon nitride materials after prolonged holding at high temperatures under vacuum and in a protective atmosphere (nitrogen). Reaction-sintered Si3N 4 having a porosity 0 = 59.3-68.0% was used in this investigation. In order to obtain a porous material, we used 1.0-1.5

V. N. Antsiferov; V. G. Gilev; A. G. Lanin; O. N. Erin; V. N. Turchin; S. V. Leonov

1993-01-01

31

Templating rare-earth hybridization via ultrahigh vacuum annealing of ErCl3 nanowires inside carbon nanotubes  

NASA Astrophysics Data System (ADS)

Here we report on controlling the effective hybridization and charge transfer of rare-earth elements inside a carbon nanotube (CNT) nanoreactor. The tubular space inside CNTs can encapsulate one-dimensional (1D) crystals such as ErCl3, which we have used as a starting material. Applying a thermochemical reaction in ultrahigh vacuum, we obtain elemental Er nanowires still encapsulated in the CNTs. The hybridization degree and the effective charge changes were directly accessed across the Er 4d and 3d edges by high-energy spectroscopy. It was found that Er is trivalent but the effective valence is reduced for the Er-filled tube, which strongly suggests an increased hybridization between the nanotube ? states and the Er 5d orbitals. This was also evidenced by the conduction band response determined in C1s-x-ray absorption spectroscopy (XAS). These results have significant implications for the 1D electronic and magnetic properties of these and similar rare-earth nanowire hybrids.

Ayala, Paola; Kitaura, Ryo; Nakanishi, Ryo; Shiozawa, Hidetsugu; Ogawa, Daisuke; Hoffmann, Patrick; Shinohara, Hinsanori; Pichler, Thomas

2011-02-01

32

In-situ x-ray diffraction studies on post-deposition vacuum-annealing of ultra-thin iron oxide films  

SciTech Connect

A maghemite ({gamma}-Fe{sub 2}O{sub 3}) film of 8.3 nm thickness is epitaxially grown on MgO(001) single crystal substrate by reactive molecular beam epitaxy. Chemical composition and crystal structure of the surface was studied by x-ray photoelectron spectroscopy and low energy electron diffraction, respectively. Afterwards the sample was moved to a heating cell for in situ x-ray diffraction experiments on the post-deposition annealing process in high-vacuum to study structural phase transitions of the iron oxide film. The iron oxide film is reduced with increasing temperature. This reduction occurs in two steps that are accompanied by structural transitions. The first step is a reduction from {gamma}-Fe{sub 2}O{sub 3} to Fe{sub 3}O{sub 4} at 360 deg. C and the second step is the reduction from Fe{sub 3}O{sub 4} to FeO at 410 deg. C.

Bertram, F.; Deiter, C.; Pflaum, K. [Hamburger Synchrotronstrahlungslabor am Deutschen Elektronen-Synchrotron, Notkestr. 85, 22607 Hamburg (Germany); Suendorf, M.; Otte, C.; Wollschlaeger, J. [Physics Department, University Osnabrueck, Barbarastr. 7, 49069 Osnabrueck (Germany)

2011-11-15

33

Effect of Ti3SiC2 formation on p-type GaN by vacuum annealing on the contact properties  

NASA Astrophysics Data System (ADS)

In the present study, after the formation of Ti3SiC2 on p-type GaN by depositing Ti- Si-C ternary film with a composition stoichiometrically close to Ti3SiC2 and subsequent annealing at temperatures of 973 K and 1073 K (lower than the annealing temperature for a contact between p-type SiC and Ti3SiC2), the resulting contact properties were analysed by X- ray diffraction, a direct-current conduction test, and a Hall-effect measurement test. The X-ray diffraction results reveal that the Ti3SiC2 phase is successfully formed after the annealing. The direct-current conduction test shows that ohmic-like contacts are achieved after the formation of Ti3SiC2. However, the Hall-effect measurement test reveals that the dominant carrier type of the specimens is inverted from p-type to n-type even after the annealing at 973 K. The N vacancy formation during the annealing is likely the cause of this change. The contact properties of the annealed specimens are discussed because it is difficult to achieve ohmic contact formation between n-type GaN and Ti3SiC2.

Mohd Halil, Aiman bin; Maeda, Masakatsu; Takahashi, Yasuo

2014-08-01

34

Depth profile investigation of ?-FeSi2 formed in Si(1 0 0) by high fluence implantation of 50 keV Fe ion and post-thermal vacuum annealing  

NASA Astrophysics Data System (ADS)

A single phase polycrystalline ?-FeSi2 layer has been synthesized at the near surface region by implantation in Si(1 0 0) of a high fluence (?1017 atoms/cm2) of 50 keV Fe ions and subsequent thermal annealing in vacuum at 800 °C. The depth profile of the implanted Fe atoms in Si(1 0 0) were simulated by the widely used transportation of ions in matter (TRIM) computer code as well as by the dynamic transportation of ions in matter code (T-DYN). The simulated depth profile predictions for this heavy ion implantation process were experimentally verified using Rutherford Backscattering Spectrometry (RBS) and X-ray Photoelectron Spectroscopy (XPS) in combination with Ar-ion etching. The formation of the ?-FeSi2 phase was monitored by X-ray diffraction measurements. The T-DYN simulations show better agreement with the experimental Fe depth profile results than the static TRIM simulations. The experimental and T-DYN simulated results show an asymmetric distribution of Fe concentrated more toward the surface region of the Si substrate.

Lakshantha, Wickramaarachchige J.; Kummari, Venkata C.; Reinert, Tilo; McDaniel, Floyd D.; Rout, Bibhudutta

2014-08-01

35

Paranormal phenomena  

NASA Astrophysics Data System (ADS)

Critical analysis is given of some paranormal phenomena events (UFO, healers, psychokinesis (telekinesis))reported in Moldova. It is argued that correct analysis of paranormal phenomena should be made in the framework of electromagnetism.

Gaina, Alex

1996-08-01

36

An Effect of Annealing on Shielding Properties of Shungite  

NASA Astrophysics Data System (ADS)

Annealing of shungite is studied in oxidizing conditions in a chamber with NH4Cl, and in vacuum at 900 °C for 2h. Frequency dependencies of transmission and reflection coefficients of annealed shungite are measured in the frequency range of 8-12 GHz. The minimum reflection at 8-10 GHz was shown for shungite annealed in the oxidizing atmosphere.

Belousova, E. S.; Mahmoud, M. Sh.; Lynkou, L. M.

2013-05-01

37

Transport Phenomena.  

ERIC Educational Resources Information Center

Discusses the problems created in graduate chemical engineering programs when students enter with a wide diversity of understandings of transport phenomena. Describes a two-semester graduate transport course sequence at the University of Notre Dame which focuses on fluid mechanics and heat and mass transfer. (TW)

McCready, Mark J.; Leighton, David T.

1987-01-01

38

Fluctuation phenomena  

SciTech Connect

Fluctuation phenomena are the ''tip of the iceberg'' revealing the existence, behind even the most quiescent appearing macroscopic states, of an underlying world of agitated, ever-changing microscopic processes. While the presence of these fluctuations can be ignored in some cases, e.g. if one is satisfied with purely thermostatic description of systems in equilibrium, they are central to the understanding of other phenomena, e.g. the nucleation of a new phase following the quenching of a system into the co-existence region. This volume contains a collection of review articles, written by experts in the field, on the subject of fluctuation phenomena. Some of the articles are of a very general nature discussing the modern mathematical formulation of the problems involved, while other articles deal with specific topics such as kinetics of phase transitions and conductivity in solids. The juxtaposition of the variety of physical situations in which fluctuation phenomena play an important role is novel and should give the reader an insight into this subject.

Montroll, E.W.; Lebowitz, J.L.

1986-01-01

39

Annealing of silicon optical fibers  

NASA Astrophysics Data System (ADS)

The recent realization of silicon core optical fibers has the potential for novel low insertion loss rack-to-rack optical interconnects and a number of other uses in sensing and biomedical applications. To the best of our knowledge, incoherent light source based rapid photothermal processing (RPP) was used for the first time to anneal glass-clad silicon core optical fibers. X-ray diffraction examination of the silicon core showed a considerable enhancement in the length and amount of single crystallinity post-annealing. Further, shifts in the Raman frequency of the silicon in the optical fiber core that were present in the as-drawn fibers were removed following the RPP treatment. Such results indicate that the RPP treatment increases the local crystallinity and therefore assists in the reduction of the local stresses in the core, leading to more homogenous fibers. The dark current-voltage characteristics of annealed silicon optical fiber diodes showed lower leakage current than the diodes based on as-drawn fibers. Photons in UV and vacuum ultraviolet (VUV) regions play a very important role in improving the bulk and carrier transport properties of RPP-treated silicon optical fibers, and the resultant annealing permits a path forward to in situ enhancement of the structure and properties of these new crystalline core optical fibers.

Gupta, N.; McMillen, C.; Singh, R.; Podila, R.; Rao, A. M.; Hawkins, T.; Foy, P.; Morris, S.; Rice, R.; Poole, K. F.; Zhu, L.; Ballato, J.

2011-11-01

40

Movement of oxygen vacancies in oxide film during annealing observed by an optical reflectivity difference technique  

E-print Network

Movement of oxygen vacancies in oxide film during annealing observed by an optical reflectivity. The growth and annealing of the film in vacuum and in oxygen ambient are monitored in real time by an oblique tell whether the oxygen vacancies are moving into or moving out of the film during the annealing

Zhu, Xiangdong

41

Post-annealed gallium and aluminum co-doped zinc oxide films applied in organic photovoltaic devices.  

PubMed

Gallium and aluminum co-doped zinc oxide (GAZO) films were produced by magnetron sputtering. The GAZO films were post-annealed in either vacuum or hydrogen microwave plasma. Vacuum- and hydrogen microwave plasma-annealed GAZO films show different surface morphologies and lattice structures. The surface roughness and the spacing between adjacent (002) planes decrease; grain growth occurs for the GAZO films after vacuum annealing. The surface roughness increases and nanocrystals are grown for the GAZO films after hydrogen microwave plasma annealing. Both vacuum and hydrogen microwave plasma annealing can improve the electrical and optical properties of GAZO films. Hydrogen microwave plasma annealing improves more than vacuum annealing does for GAZO films. An electrical resistivity of 4.7?×?10(-4) ?-cm and average optical transmittance in the visible range from 400 to 800 nm of 95% can be obtained for the GAZO films after hydrogen microwave plasma annealing. Hybrid organic photovoltaic (OPV) devices were fabricated on the as-deposited, vacuum-annealed, and hydrogen microwave plasma-annealed GAZO-coated glass substrates. The active layer consisted of blended poly(3-hexylthiophene) (P3HT) and [6,6]-phenyl C61 butyric acid methyl ester (PCBM) in the OPV devices. The power conversion efficiency of the OPV devices is 1.22% for the hydrogen microwave plasma-annealed GAZO films, which is nearly two times higher compared with that for the as-deposited GAZO films. PMID:25352768

Chang, Shang-Chou

2014-01-01

42

Vacuum Technology  

SciTech Connect

The environmental condition called vacuum is created any time the pressure of a gas is reduced compared to atmospheric pressure. On earth we typically create a vacuum by connecting a pump capable of moving gas to a relatively leak free vessel. Through operation of the gas pump the number of gas molecules per unit volume is decreased within the vessel. As soon as one creates a vacuum natural forces (in this case entropy) work to restore equilibrium pressure; the practical effect of this is that gas molecules attempt to enter the evacuated space by any means possible. It is useful to think of vacuum in terms of a gas at a pressure below atmospheric pressure. In even the best vacuum vessels ever created there are approximately 3,500,000 molecules of gas per cubic meter of volume remaining inside the vessel. The lowest pressure environment known is in interstellar space where there are approximately four molecules of gas per cubic meter. Researchers are currently developing vacuum technology components (pumps, gauges, valves, etc.) using micro electro mechanical systems (MEMS) technology. Miniature vacuum components and systems will open the possibility for significant savings in energy cost and will open the doors to advances in electronics, manufacturing and semiconductor fabrication. In conclusion, an understanding of the basic principles of vacuum technology as presented in this summary is essential for the successful execution of all projects that involve vacuum technology. Using the principles described above, a practitioner of vacuum technology can design a vacuum system that will achieve the project requirements.

Biltoft, P J

2004-10-15

43

Vacuum mechatronics  

NASA Technical Reports Server (NTRS)

The discipline of vacuum mechatronics is defined as the design and development of vacuum-compatible computer-controlled mechanisms for manipulating, sensing and testing in a vacuum environment. The importance of vacuum mechatronics is growing with an increased application of vacuum in space studies and in manufacturing for material processing, medicine, microelectronics, emission studies, lyophylisation, freeze drying and packaging. The quickly developing field of vacuum mechatronics will also be the driving force for the realization of an advanced era of totally enclosed clean manufacturing cells. High technology manufacturing has increasingly demanding requirements for precision manipulation, in situ process monitoring and contamination-free environments. To remove the contamination problems associated with human workers, the tendency in many manufacturing processes is to move towards total automation. This will become a requirement in the near future for e.g., microelectronics manufacturing. Automation in ultra-clean manufacturing environments is evolving into the concept of self-contained and fully enclosed manufacturing. A Self Contained Automated Robotic Factory (SCARF) is being developed as a flexible research facility for totally enclosed manufacturing. The construction and successful operation of a SCARF will provide a novel, flexible, self-contained, clean, vacuum manufacturing environment. SCARF also requires very high reliability and intelligent control. The trends in vacuum mechatronics and some of the key research issues are reviewed.

Hackwood, Susan; Belinski, Steven E.; Beni, Gerardo

1989-01-01

44

Vacuum Energy  

E-print Network

There appears to be three, perhaps related, ways of approaching the nature of vacuum energy . The first is to say that it is just the lowest energy state of a given, usually quantum, system. The second is to equate vacuum energy with the Casimir energy. The third is to note that an energy difference from a complete vacuum might have some long range effect, typically this energy difference is interpreted as the cosmological constant. All three approaches are reviewed, with an emphasis on recent work. It is hoped that this review is comprehensive in scope. There is a discussion on whether there is a relation between vacuum energy and inertia. The solution suggested here to the nature of the vacuum is that Casimir energy can produce short range effects because of boundary conditions, but that at long range there is no overall effect of vacuum energy, unless one considers lagrangians of higher order than Einstein's as vacuum induced. No original calculations are presented in support of this position. This is not a review of the cosmological constant {\\it per se}, but rather vacuum energy in general, my approach to the cosmological constant is not standard.

Mark D. Roberts

2000-12-07

45

Vacuum Virtues  

ERIC Educational Resources Information Center

Upright vacuums, like cars, vary in quality, features and performance. Like automobiles, some uprights are reliable, others may be problematic, and some become a problem as a result of neglect or improper use. So, how do education institutions make an informed choice and, having done so, ensure that an upright vacuum goes the distance? In this…

Rathey, Allen

2007-01-01

46

Gravitational vacuum  

NASA Astrophysics Data System (ADS)

The existence of a special gravitational vacuum is considered in this paper. A phenomenological method differing from the traditional Einsteinian formalization is utilized. Vacuum, metric and matter form a complex determined by field equations and at great distances from gravitational masses vacuum effects are small but could be large in powerful fields. Singularities and black holes justify the approach as well as the Ambartsmyan theory concerning the existence of supermassive and superdense prestallar bodies that then disintegrate. A theory for these superdense bodies is developed involving gravitational field equations that describe the vacuum by an energy momentum tensor and define the field and mass distribution. Computations based on the theory for gravitational radii with incompressible liquid models adequately reflecting real conditions indicate that a gravitational vacuum could have considerable effects on superdense stars and could have radical effects for very large masses.

Grigoryan, L. S.; Saakyan, G. S.

1984-09-01

47

Annealing-insensitive "black silicon" with high infrared absorption  

NASA Astrophysics Data System (ADS)

A black silicon structure with high-aspect-ratio surface spikes was designed and fabricated in vacuum, resulting in absorptance >90% over the range of 200-2500 nm. It is demonstrated that annealing, an essential step in the fabrication of semiconductor devices, has almost no effect on the infrared absorption of this material, while the infrared absorption of an identical structure fabricated in a SF6 drops dramatically after the annealing process. The characteristic of high infrared absorption and annealing-insensitivity is attributed to both the high-aspect-ratio structure and the phosphor-doped low impedance silicon. These results are important for the fabrication of highly efficient optoelectronic devices.

Peng, Yan; Chen, Xiangqian; Zhou, Yunyan; Xu, Gongjie; Cai, Bin; Zhu, Yiming; Xu, Jian; Henderson, Ron; Dai, Jianming

2014-08-01

48

Tuning magnetic properties of yttrium iron garnet film with oxygen partial pressure in sputtering and annealing process  

SciTech Connect

In this paper, the magnetic properties of these films which deposited and annealed at different atmospheres were investigated. The experimental results show that the magnetic properties of yttrium iron garnet films prepared by rf magnetron sputtering method can be tuned with oxygen partial pressure in sputtering and annealing processes. The optimal condition is depositing in atmosphere of R=0 and annealing at 0.5 Pa O{sub 2}, or depositing in atmosphere of R=2% and annealed in vacuum.

Yang Qinghui; Zhang Huaiwu; Wen Qiye; Liu Yingli [State Key Laboratory of Electronic Films and Integrated Devices, University of Electronic Science and Technology of China, Chengdu 610054 (China); Xiao, John Q. [Department of Physics and Astronomy, University of Delaware, Newark, Delaware 19716 (United States)

2009-04-01

49

A numerical simulation of the phenomena in Be plasma  

NASA Astrophysics Data System (ADS)

In this paper, we present the numerical simulation of the Be deposition phenomena using the Thermionic Vacuum Arc (TVA) method. The Be marker layer must be adherent to the substrate and compact to resemble bulk beryllium. Thermionic Vacuum Arc (TVA) is an externally heated cathode arc which can be established in high vacuum condition, in vapors of the anode material. The arc is ignited between a heated cathode provided with a Whenelt cylinder and the anode which is a crucible containing the material to be evaporated [1]. We have used the COMSOL software to simulate the Be deposition phenomena using the TVA method.

Gavrila, Camelia; Lungu, Cristian P.; Gruia, Ion

2011-05-01

50

Vacuum Gauges  

NSDL National Science Digital Library

This is a description for a learning module from Maricopa Advanced Technology Education Center. This PDF describes the module; access may be purchased by visiting the MATEC website. Semiconductor manufacturing equipment requires the use of many different types of vacuum gauges. Selection is based on range of process operations and production requirements. This MATEC module explores the theory and functionality of vacuum gauges and provides many examples of different types of gauges. The focus is on understanding the operating ranges and application constraints of each type of gauge. Mathematical equations are used to explain calibration, sensitivity, and overall operations of each type of gauge.

2012-11-28

51

Photochemically deposited and post annealed copper indium disulphide thin films  

NASA Astrophysics Data System (ADS)

Copper indium disulfide (CIS) thin films were deposited using novel photochemical deposition (PCD) technique by selective deposition parameters. In this work CIS film deposition was made by cationic, anionic precursor solution concentration ratio 1:1:2. Na2EDTA was used as a chelating agent. The as deposited CIS films were post annealed at different temperatures up to 400 °C in vacuum. The as deposited and annealed CIS films were examined to reveal the structural, optical, morphological, compositional and electrical properties by X-ray diffraction, Raman analysis, UV-Vis spectroscopy, Scanning Electron Microscopy, TEM, EDX and Hall effect respectively. From the XRD and Raman studies the Cu-Au ordering was confirmed both in as deposited and annealed films. The crystallite size increases with increasing of annealing temperature and the surface structuring shows rod like microstructure.

Suriakarthick, R.; Nirmal Kumar, V.; Indirajith, R.; Shyju, T. S.; Gopalakrishnan, R.

2014-11-01

52

Quantum vacuum and dark matter  

E-print Network

Recently, the gravitational polarization of the quantum vacuum was proposed as alternative to the dark matter paradigm. In the present paper we consider four benchmark measurements: the universality of the central surface density of galaxy dark matter haloes, the cored dark matter haloes in dwarf spheroidal galaxies, the non-existence of dark disks in spiral galaxies and distribution of dark matter after collision of clusters of galaxies (the Bullet cluster is a famous example). Only some of these phenomena (but not all of them) can (in principle) be explained by the dark matter and the theories of modified gravity. However, we argue that the framework of the gravitational polarization of the quantum vacuum allows the understanding of the totality of these phenomena.

Dragan Slavkov Hajdukovic

2011-11-21

53

Effect of Annealing on Slightly Oxidized Silicon Surface  

NASA Astrophysics Data System (ADS)

We investigated the effect of annealing on slightly oxidized silicon surfaces by using atomic force microscopy (AFM), Auger electron spectroscopy (AES) and X-ray photoelectron spectroscopy (XPS). The very thin oxide films (˜1 nm) were made by chemical treatment for three kinds of samples. One of them was p-type Si(100) wafer, the others were heavily phosphorus-doped Si(100) wafers made by ion implantation and low pressure chemical vapor deposition. These samples were annealed at low temperature (700°C˜900°C) in ultra high vacuum. AFM measurements showed that RMS roughness of all surfaces after annealing in UHV was several times as much as that of the surfaces right after chemical treatment. The morphology of every sample after oxide silicon desorbed by annealing revealed dot shape. And the morphology of p-type Si(100) after annealing at 730°C resembled that of heavily phosphorus-doped Si(100) made by ion implantation after annealing at 830°C. AES and XPS measurements showed that the difference of annealing temperature for these samples was due to the difference of their oxide thickness and the quality of their oxides.

Kakimoto, Masashi; Sano, Yuichi; Kamiura, Yoshitomo; Mizokawa, Yusuke

54

GenAnneal: Genetically modified Simulated Annealing  

NASA Astrophysics Data System (ADS)

A modification of the standard Simulated Annealing (SA) algorithm is presented for finding the global minimum of a continuous multidimensional, multimodal function. We report results of computational experiments with a set of test functions and we compare to methods of similar structure. The accompanying software accepts objective functions coded both in Fortran 77 and C++. Program summaryTitle of program:GenAnneal Catalogue identifier:ADXI_v1_0 Program summary URL:http://cpc.cs.qub.ac.uk/summaries/ADXI_v1_0 Program available from: CPC Program Library, Queen's University of Belfast, N. Ireland Computer for which the program is designed and others on which it has been tested: The tool is designed to be portable in all systems running the GNU C++ compiler Installation: University of Ioannina, Greece on Linux based machines Programming language used:GNU-C++, GNU-C, GNU Fortran 77 Memory required to execute with typical data: 200 KB No. of bits in a word: 32 No. of processors used: 1 Has the code been vectorized or parallelized?: No No. of bytes in distributed program, including test data, etc.:84 885 No. of lines in distributed program, including test data, etc.:14 896 Distribution format: tar.gz Nature of physical problem: A multitude of problems in science and engineering are often reduced to minimizing a function of many variables. There are instances that a local optimum does not correspond to the desired physical solution and hence the search for a better solution is required. Local optimization techniques are frequently trapped in local minima. Global optimization is hence the appropriate tool. For example, solving a non-linear system of equations via optimization, employing a "least squares" type of objective, one may encounter many local minima that do not correspond to solutions (i.e. they are far from zero). Typical running time: Depending on the objective function. Method of solution: We modified the process of step selection that the traditional Simulated Annealing employs and instead we used a global technique based on grammatical evolution.

Tsoulos, Ioannis G.; Lagaris, Isaac E.

2006-05-01

55

[Effects of different annealing conditions on the photoluminescence of nanoporous alumina film].  

PubMed

The nanoporous alumina films were prepared by two-step anodic oxidation in 0.5 mol L-1 oxalic acid electrolyte at 40 V. Photoluminescence (PL) of nanoporous alumina films was investigated under different annealing atmosphere and different temperature. The authors got three results about the PL measurements. In the same annealing atmosphere, when the annealling temperature T< or =600 degreeC, the intensity of the PL peak increases with elevated annealing temperature and reaches a maximum value at 500 degreeC, but the intensity decreases with a further increase in the annealing temperature, and the PL peak intensity of samples increases with the increase in the annealing temperature when the annealling temperature T> or =800 degreeC. In the different annealling atmosphere, the change in the photoluminescence peak position for nanoporous alumina films with the increase in the annealing temperature is different: With the increase in the annealling temperature, the PL peak position for the samples annealed in air atmosphere is blue shifted, while the PL peak position for the samples annealed in vacuum atmosphere will not change. The PL spectra of nanoporous alumina films annealed at 1100 degreeC in air atmosphere can be de-convoluted by three Gaussian components at an excitation wavelength of 350 nm, with bands centered at 387, 410 and 439 nm, respectively. These results suggest that there might be three luminescence centers for the PL of annealed alumina films. At the same annealling temperature, the PL peak intensity of samples annealed in air atmosphere is stronger than that annealed in the vacuum. Based on the experimental results and the X-ray dispersive energy spectrum (EDS) combined with infrared reflect spectra, the luminescence mechanisms of nanoporous alumina films are discussed. There are three luminescence centers in the annealed nanoporous alumina films, which originate from the F center, F+ center and the center associated with the oxalic impurities. The effects of different annealing conditions on the photoluminescence of nanoporous alumina film are reasonably explained. PMID:24611369

Xie, Ning; Ma, Kai-Di; Shen, Yi-Fan; Wang, Qian

2013-12-01

56

EFFECT OF THERMAL ANNEALING ON THE THERMOLUMINESCENT PROPERTIES OF NANO-CALCIUM FLUORIDE AND ITS DOSE-RESPONSE CHARACTERISTICS.  

PubMed

Nano-CaF2, prepared by the co-precipitation method, was annealed under different annealing conditions to improve its thermoluminescence (TL) characteristics. Different annealing parameters, such as temperature (400-700°C), duration (1-4 h) and environment (vacuum and air), were explored. The effect on TL sensitivity, peak position (Tm) and full-width at half-maximum (FWHM) with respect to the different annealing conditions are discussed as they are the measure of crystallinity of the material. Annealing temperature of 500°C with annealing duration of two and a half hours in vacuum provided the highest luminescence response (i.e. maximum sensitivity, minimum peak temperature and FWHM). Wide detectable dose range (5 mGy to 2 kGy), absence of thermal quenching and sufficient activation energy (1.04 eV) of this phosphor make it suitable for dosimetric applications. PMID:25398396

Mundupuzhakal, J K; Biswas, R H; Chauhan, S; Varma, V; Acharya, Y B; Chakrabarty, B S

2014-11-13

57

Coupled Phenomena in Chemistry.  

ERIC Educational Resources Information Center

Various phenomena in chemistry and biology can be understood through Gibbs energy utilization. Some common phenomena in chemistry are explained including neutralization, hydrolysis, oxidation and reaction, simultaneous dissociation equilibrium of two weak acids, and common ion effect on solubility. (Author/SA)

Matsubara, Akira; Nomura, Kazuo

1979-01-01

58

Morphological variations in AuxSiy nanostructures under variable pressure and annealing conditions  

NASA Astrophysics Data System (ADS)

Well-ordered, substrate symmetry-driven, AuxSiy structures of average size ~25 nm were formed under ultra-high vacuum (UHV) conditions using molecular beam epitaxy method. Post-annealing was done at 500 °C in three different vacuum conditions: (1) low vacuum (LV) (10-2 mbar), (2) high vacuum (HV) (10-5 mbar) and (3) UHV (10-10 mbar) (MBE chamber). For both HV and LV cases, the AuxSiy nanostructures were found to have their corners rounded unlike in UHV case where the structures have sharp edges. In all the above three cases, samples were exposed to air before annealing. In situ annealing inside UHV chamber without exposing to air resulted in well-aligned rectangles with sharp corners, while sharp but irregular island structures were found for air exposed and UHV annealing system. The role of residual gases present in LV and HV annealing environment and inhibition of lateral surface diffusion due to the presence of surface oxide (through air exposure) would be discussed. Annealing at various conditions yielded variation in the coverage and correspondingly, the average area of nanostructures varied from a ~329 nm2 (as deposited) to ~2,578 nm2 (at high temperature). High-resolution transmission electron microscopy (planar and cross section) has been utilized to study the morphological variations.

Rath, A.; Dash, J. K.; Juluri, R. R.; Satyam, P. V.

2014-11-01

59

Structural and electrical characteristics of Ga2O3(Gd2O3)\\/GaAs under high temperature annealing  

Microsoft Academic Search

Atomically smooth Ga2O3(Gd2O3)\\/GaAs interface with low interfacial density of states and low electrical leakage currents have been achieved after the heterostructures were air exposed and tailor annealed to ~750 °C. The heat treatments, with annealing at an intermediate temperature of ~300 °C as a necessary step, were carried out under ultrahigh vacuum (UHV) and via standard rapid thermal annealing with

C. P. Chen; Y. J. Lee; Y. C. Chang; Z. K. Yang; M. Hong; J. Kwo; H. Y. Lee; T. S. Lay

2006-01-01

60

Effects of H2 Atmosphere Annealing on the Properties of CZT:In Single Crystals  

NASA Astrophysics Data System (ADS)

To improve crystal quality and detector performance, high-resistivity cadmium zinc telluride (CZT):In single crystals were annealed in H2. The concentration of Te inclusions did not change after annealing. Both the resistivity and infrared transmittance increased as the annealing time increased, indicating improvement of crystal quality. Because of the passivation by hydrogen, some interesting phenomena were observed in the photoluminescence spectra of as-grown and annealed CZT:In crystals. Moreover, the energy resolution was remarkably enhanced. After 4 h, 8 h, and 12 h of annealing, the energy resolution was improved 33%, 79%, and 49%, respectively. The crystal annealed for 8 h with energy resolution of 9.29% had the best detector performance.

Yu, P. F.; Jie, W. Q.

2013-12-01

61

Recent advances in vacuum sciences and applications  

NASA Astrophysics Data System (ADS)

Recent advances in vacuum sciences and applications are reviewed. Novel optical interferometer cavity devices enable pressure measurements with ppm accuracy. The innovative dynamic vacuum standard allows for pressure measurements with temporal resolution of 2 ms. Vacuum issues in the construction of huge ultra-high vacuum devices worldwide are reviewed. Recent advances in surface science and thin films include new phenomena observed in electron transport near solid surfaces as well as novel results on the properties of carbon nanomaterials. Precise techniques for surface and thin-film characterization have been applied in the conservation technology of cultural heritage objects and recent advances in the characterization of biointerfaces are presented. The combination of various vacuum and atmospheric-pressure techniques enables an insight into the complex phenomena of protein and other biomolecule conformations on solid surfaces. Studying these phenomena at solid-liquid interfaces is regarded as the main issue in the development of alternative techniques for drug delivery, tissue engineering and thus the development of innovative techniques for curing cancer and cardiovascular diseases. A review on recent advances in plasma medicine is presented as well as novel hypotheses on cell apoptosis upon treatment with gaseous plasma. Finally, recent advances in plasma nanoscience are illustrated with several examples and a roadmap for future activities is presented.

Mozeti?, M.; Ostrikov, K.; Ruzic, D. N.; Curreli, D.; Cvelbar, U.; Vesel, A.; Primc, G.; Leisch, M.; Jousten, K.; Malyshev, O. B.; Hendricks, J. H.; Kövér, L.; Tagliaferro, A.; Conde, O.; Silvestre, A. J.; Giapintzakis, J.; Buljan, M.; Radi?, N.; Draži?, G.; Bernstorff, S.; Biederman, H.; Kylián, O.; Hanuš, J.; Miloševi?, S.; Galtayries, A.; Dietrich, P.; Unger, W.; Lehocky, M.; Sedlarik, V.; Stana-Kleinschek, K.; Drmota-Petri?, A.; Pireaux, J. J.; Rogers, J. W.; Anderle, M.

2014-04-01

62

Indium out-diffusion in Al2O3/InGaAs stacks during anneal at different ambient conditions  

NASA Astrophysics Data System (ADS)

Indium out-diffusion during anneal enhances leakage currents in metal/dielectric/InGaAs gate stacks. In this work, we study the influence of ambient conditions during anneal on indium out-diffusion in Al2O3/InGaAs structures, prior to the gate metal deposition. Using X-ray photoemission spectroscopy and time of flight secondary ions mass spectrometry, we observed much lower indium concentrations in the Al2O3 layer following vacuum and O2 anneals compared to forming gas or nitrogen anneals. The electrical characteristics of the Ni/Al2O3/InGaAs gate stack following these pre-metallization anneals as well as after subsequent post metallization anneals are presented. Possible explanations for the role of the annealing ambient conditions on indium out-diffusion are presented.

Krylov, Igor; Winter, Roy; Ritter, Dan; Eizenberg, Moshe

2014-06-01

63

DC reactive magnetron sputtering, annealing, and characterization of CuAlO2 thin films  

E-print Network

exhibiting the delafossite structure along with CuO, AlOOH, and Al2O3. © 2011 American Vacuum Society. DOIDC reactive magnetron sputtering, annealing, and characterization of CuAlO2 thin films Blake L://avspublications.org/jvsta/about/rights_and_permissions #12;DC reactive magnetron sputtering, annealing, and characterization of CuAlO2 thin films Blake L

Poeppelmeier, Kenneth R.

64

Vacuum alignment and lattice artifacts  

E-print Network

When a subgroup of the flavor symmetry group of a gauge theory is weakly coupled to additional gauge fields, the vacuum tends to align such that the gauged subgroup is unbroken. At the same time, the lattice discretization typically breaks the flavor symmetry explicitly, and can give rise to new lattice-artifact phases with spontaneously broken symmetries. We discuss the interplay of these two phenomena, using chiral lagrangian techniques. Our first example is two-flavor Wilson QCD coupled to electromagnetism. We also consider examples of theories with staggered fermions, and demonstrate that recent claims in the literature based on the use of staggered fermions are incorrect.

Maarten Golterman; Yigal Shamir

2014-10-29

65

Wear of Steel and Ti6Al4V Rollers in Vacuum  

NASA Technical Reports Server (NTRS)

This investigation was prompted by results of a qualification test of a mechanism to be used for the James Webb Space Telescope. Post-test inspections of the qualification test article revealed some loose wear debris and wear of the steel rollers and the mating Ti6Al4V surfaces. An engineering assessment of the design and observations from the tested qualification unit suggested that roller misalignment was a controlling factor. The wear phenomena were investigated using dedicated laboratory experiments. Tests were done using a vacuum roller rig for a range of roller misalignment angles. The wear in these tests was mainly adhesive wear. The measured wear rates were highly correlated to the misalignment angle. For all tests with some roller misalignment, the steel rollers lost mass while the titanium rollers gained mass indicating strong adhesion of the steel with the titanium alloy. Inspection of the rollers revealed that the adhesive wear was a two-way process as titanium alloy was found on the steel rollers and vice versa. The qualification test unit made use of 440F steel rollers in the annealed condition. Both annealed 440F steel rollers and hardened 440C rollers were tested in the vacuum roller rig to investigate possibility to reduce wear rates and the risk of loose debris formation. The 440F and 440C rollers had differing wear behaviors with significantly lesser wear rates for the 440C. For the test condition of zero roller misalignment, the adhesive wear rates were very low, but still some loose debris was formed

Krantz, Timothy L.; Shareef, Iqbal

2012-01-01

66

Experimental study and process parameters analysis on the vacuum cooling of iceberg lettuce  

Microsoft Academic Search

The vacuum cooling of iceberg lettuce was described in this paper. Based on the energy and mass balance, a mathematical model was developed to analyze the performance of the vacuum cooler and the evaporation–boiling phenomena during vacuum cooling of iceberg lettuce. The temporal trends of total system pressure, produce temperature such as surface temperature, center temperature, mass–average temperature, the weight

Su-Yan He; Yun-Fei Li

2008-01-01

67

Ion exchange phenomena  

SciTech Connect

Ion exchange phenomena involve the population of readily exchangeable ions, the subset of adsorbed solutes that balance the intrinsic surface charge and can be readily replaced by major background electrolyte ions (Sposito, 2008). These phenomena have occupied a central place in soil chemistry research since Way (1850) first showed that potassium uptake by soils resulted in the release of an equal quantity of moles of charge of calcium and magnesium. Ion exchange phenomena are now routinely modeled in studies of soil formation (White et al., 2005), soil reclamation (Kopittke et al., 2006), soil fertilitization (Agbenin and Yakubu, 2006), colloidal dispersion/flocculation (Charlet and Tournassat, 2005), the mechanics of argillaceous media (Gajo and Loret, 2007), aquitard pore water chemistry (Tournassat et al., 2008), and groundwater (Timms and Hendry, 2007; McNab et al., 2009) and contaminant hydrology (Chatterjee et al., 2008; van Oploo et al., 2008; Serrano et al., 2009).

Bourg, I.C.; Sposito, G.

2011-05-01

68

Adjustable metal-semiconductor transition of FeS thin films by thermal annealing  

SciTech Connect

FeS polycrystalline thin films were prepared on float glass at 500 deg. C by radio-frequency reactive sputtering. The influence of vacuum annealing on the metal-semiconductor transition of FeS films was investigated. It has been found that with the increase of the annealing temperature from 360 to 600 deg. C, the metal-semiconductor transition temperature of FeS films first decreases and then increases, associated with first a reduction and then an enhancement of hysteresis width. The thermal stress is considered to give rise to the abnormal change of the metal-semiconductor transition of the FeS film during annealing.

Fu Ganhua; Polity, Angelika; Volbers, Niklas; Meyer, Bruno K.; Mogwitz, Boris; Janek, Juergen [I. Physikalisches Institut, Justus-Liebig-Universitaet Giessen, Heinrich-Buff-Ring 16, D-35392 Giessen (Germany); Physikalisch-Chemisches Institut, Justus-Liebig-Universitaet Giessen, Heinrich-Buff-Ring 58, D-35392 Giessen (Germany)

2006-12-25

69

Flavor singlet phenomena in lattice QCD  

E-print Network

Flavor singlet combinations of quark operators ${\\cal{O}}_S^{\\Gamma} = \\bar{u}\\Gamma u + \\bar{d}\\Gamma d + \\bar{s}\\Gamma s$ contribute to many important physical observables in the low energy region of QCD. Experimentally one finds the values of some of these observables to be in sharp contrast to the naive (perturbative) theoretical expectations. This indicates that non perturbative vacuum properties might play a major role in the comprehension of these phenomena. An example of such a vacuum contribution is the axial anomaly, which appears in the divergence of the flavor singlet axial current and which is connected to the topological properties of QCD. From a field theoretical point of view flavor singlet matrix elements differ from non singlet amplitudes in the occurrence of so called disconnected insertions. These are correlations of hadron propagators with quark-antiquark loops or correlations between quark-antiquark loops, which are mediated by vacuum fluctuations. According to their respective flavor composition, the disconnected insertions cancel largely in non singlet processes, but add in flavor singlet amplitudes. The lattice approach provides an ideal tool to study flavor singlet phenomena. Being a first principle method it should be capable to uncover non perturbative vacuum contributions and to yield, on the long run, reliable results for the size of such contributions in QCD. The present article reviews the status of flavor singlet matrix element calculations in lattice QCD with respect to methods, results and reliability. Special emphasis is paid to the discussion of state of the art calculations of the pion nucleon sigma term $\\sigma_{\\pi N}$, the flavor singlet axial coupling of the proton $G_A^1$, and the $\\eta'$ mass.

S. Güsken

1999-06-28

70

Annealing to Mitigate Pitting in Electropolished Niobium Coupons and SRF Cavities  

SciTech Connect

Ongoing studies at Fermilab investigate whether dislocations and other factors instigate pitting during cavity electropolishing (EP), despite careful processing controls and the inherent leveling mechanism of EP itself. Here, cold-worked niobium coupons, which exhibited increased tendencies for pitting in our past study, were annealed in a high vacuum furnace and subsequently processed by EP. Laser confocal scanning microscopy and special defect counting algorithms were used to assess the population of pits formed. Hardness measurements indicated that annealing for 2 hours at 800 C produced recovery, whereas annealing for 12 hours at 600 C did not, as is consistent with known changes for cavities annealed in a similar way. The 800 C anneal was effective in some cases but not others, and we discuss reasons why tendencies for pitting remain. We discuss implications for cavities and continued work to understand pitting.

Cooley, L.D.; Hahn, E.; Hicks, D.; Romanenko, A.; Schuessler, R.; Thompson, C.; /Fermilab

2011-06-08

71

Enhanced reduction of silicon oxide thin films on silicon under electron beam annealing  

NASA Astrophysics Data System (ADS)

Electron beam annealing is an interesting alternative to other annealing methods as it can provide high temperature, rapid heating and cooling and low level of impurity as it operates under high vacuum environment. Furthermore swamping the materials with electrons can lead to dramatic changes in the component valence states with the mechanism involving oxido-reduction reactions. This is illustrated in the present case with the enhancement of the reduction of SiO2. Commercial thermally grown 100 and 400 nm SiO2 films on Si were annealed under three different environments: furnace annealing in open atmosphere with O2 flow, high vacuum furnace annealing and electron beam annealing. The reduction and oxidation of SiO2 films on Si are investigated using ion beam analysis. The validity of the measurement method was confirmed by measuring the oxidation rate through successive Rutherford backscattering spectrometry (RBS) measurements. The oxidation kinetics were observed to be in excellent agreement with literature values. At 1000 °C reduction of the SiO2 film is observed only with electron beam annealing. A model is proposed to explain the effect of the electron beam.

Kennedy, J.; Leveneur, J.; Fang, F.; Markwitz, A.

2014-08-01

72

Vacuum polarization and Hawking radiation  

NASA Astrophysics Data System (ADS)

Quantum gravity is one of the interesting fields in contemporary physics which is still in progress. The purpose of quantum gravity is to present a quantum description for spacetime at 10-33cm or find the 'quanta' of gravitational interaction.. At present, the most viable theory to describe gravitational interaction is general relativity which is a classical theory. Semi-classical quantum gravity or quantum field theory in curved spacetime is an approximation to a full quantum theory of gravity. This approximation considers gravity as a classical field and matter fields are quantized. One interesting phenomena in semi-classical quantum gravity is Hawking radiation. Hawking radiation was derived by Stephen Hawking as a thermal emission of particles from the black hole horizon. In this thesis we obtain the spectrum of Hawking radiation using a new method. Vacuum is defined as the possible lowest energy state which is filled with pairs of virtual particle-antiparticle. Vacuum polarization is a consequence of pair creation in the presence of an external field such as an electromagnetic or gravitational field. Vacuum polarization in the vicinity of a black hole horizon can be interpreted as the cause of the emission from black holes known as Hawking radiation. In this thesis we try to obtain the Hawking spectrum using this approach. We re-examine vacuum polarization of a scalar field in a quasi-local volume that includes the horizon. We study the interaction of a scalar field with the background gravitational field of the black hole in the desired quasi-local region. The quasi-local volume is a hollow cylinder enclosed by two membranes, one inside the horizon and one outside the horizon. The net rate of particle emission can be obtained as the difference of the vacuum polarization from the outer boundary and inner boundary of the cylinder. Thus we found a new method to derive Hawking emission which is unitary and well defined in quantum field theory.

Rahmati, Shohreh

73

Quantum phenomena in superconductors  

SciTech Connect

This paper contains remarks by the author on aspects of macroscopic quantum phenomena in superconductors. Some topics discussed are: Superconducting low-inductance undulatory galvanometer (SLUGS), charge imbalance, cylindrical dc superconducting quantum interference device (SQUIDS), Geophysics, noise theory, magnetic resonance with SQUIDS, and macroscopic quantum tunneling. 23 refs., 4 figs. (LSP)

Clarke, J.

1987-08-01

74

Neutron Star Phenomena  

NASA Technical Reports Server (NTRS)

Various phenomena involving neutron stars are addressed. Electron-positron production in the near magnetosphere of gamma-ray pulsars is discussed along with magnetic field evolution in spun-up and spinning-down pulsars. Glitches and gamma-ray central engines are also discussed.

Ruderman, Malvin

1998-01-01

75

Laser sealed vacuum insulating window  

DOEpatents

A laser sealed evacuated window panel is comprised of two glass panes held spaced apart in relation to each other by a plurality of spherical glass beads and glass welded around the edges to provide an evacuated space between the glass panes that is completely glass sealed from the exterior. The glass welded edge seal is obtained by welding the edges of the glass panes together with a laser beam while the glass panes and bead spacers are positioned in a vacuum furnace and heated to the annealing point of the glass to avoid stress fracture in the area of the glass weld. The laser welding in the furnace can be directed around the perimeter of the galss panel by a combination of rotating the glass panel and linearly translating or aiming the laser with a relay mirror.

Benson, D.K.; Tracy, C.E.

1985-08-19

76

Laser sealed vacuum insulation window  

DOEpatents

A laser sealed evacuated window panel is comprised of two glass panes held spaced apart in relation to each other by a plurality of spherical glass beads and glass welded around the edges to provide an evacuated space between the glass panes that is completely glass sealed from the exterior. The glass welded edge seal is obtained by welding the edges of the glass panes together with a laser beam while the glass panes and bead spacers are positioned in a vacuum furnace and heated to the annealing point of the glass to avoid stress fracture in the area of the glass weld. The laser welding in the furnace can be directed around the perimeter of the glass panel by a combination of rotating the glass panel and linearly translating or aiming the laser with a relay mirror.

Benson, David K. (Golden, CO); Tracy, C. Edwin (Golden, CO)

1987-01-01

77

Effects of the annealing temperature and atmosphere on the microstructures and dielectric properties of ZnO/Al2O3 composite coatings  

NASA Astrophysics Data System (ADS)

ZnO/Al2O3 composite coatings were fabricated by atmospheric plasma spraying technology (APS). The effects of annealing temperature and atmospheres (in air or vacuum) on the microstructure and phase transformation of the sprayed coatings were studied by scanning electron microscope (SEM) and X-ray diffraction spectroscopy (XRD). The microwave dielectric properties of these coatings after annealing treatment were also discussed in the frequency range of 8.2-12.4 GHz. Both the real part and the imaginary part of the permittivity decreased significantly with increased annealing temperature when the annealing process is carried out in air atmosphere, while the complex permittivity of the coating annealed in vacuum atmosphere was obviously increased compared to the initial sprayed coating. The mechanism for the variation of dielectric properties of sprayed ZnO/Al2O3 composite coating caused by annealing treatment was discussed in this study.

Wei, Ping; Zhu, Dongmei; Huang, Shanshan; Zhou, Wancheng; Luo, Fa

2013-11-01

78

The effect of post oxide deposition annealing on the effective work function in metal/Al{sub 2}O{sub 3}/InGaAs gate stack  

SciTech Connect

The effect of post oxide deposition annealing on the effective work function in metal/Al{sub 2}O{sub 3}/ InGaAs gate stacks was investigated. Using a systematic method for effective work function extraction, a shift of 0.3?±?0.1?eV was found between the effective work function of forming gas annealed samples and vacuum annealed samples. The electrical measurements enabled us to obtain the band alignment of the metal/Al{sub 2}O{sub 3}/InGaAs gate stack. This band alignment was confirmed by X-ray photoelectron spectroscopy. The measured shift in the effective work function between different annealing ambient may be attributed to indium out-diffusion during post oxide deposition annealing that is observed in forming gas anneal to a much larger extent than in vacuum.

Winter, R.; Krylov, I.; Eizenberg, M. [Department of Materials Engineering, Technion–Israel Institute of Technology, Haifa 32000 (Israel); Ahn, J.; McIntyre, P. C. [Department of Materials Science and Engineering, Stanford University, Stanford, California 94305 (United States)

2014-05-19

79

Hazardous Phenomena at Volcanoes  

USGS Publications Warehouse

Volcanoes generate a wide variety of phenomena that can alter the Earth's surface and atmosphere and endanger people and property. While most of the natural hazards illustrated and described in this fact sheet are associated with eruptions, some, like landslides, can occur even when a volcano is quiet. Small events may pose a hazard only within a few miles of a volcano, while large events can directly or indirectly endanger people and property tens to hundreds of miles away.

Myers, Bobbie M.; Brantley, Steven R.

1995-01-01

80

Membrane Transport Phenomena (MTP)  

NASA Technical Reports Server (NTRS)

The third semi-annual period of the MTP project has been involved with performing experiments using the Membrane Transport Apparatus (MTA), development of analysis techniques for the experiment results, analytical modeling of the osmotic transport phenomena, and completion of a DC-9 microgravity flight to test candidate fluid cell geometries. Preparations were also made for the MTP Science Concept Review (SCR), held on 13 June 1997 at Lockheed Martin Astronautics in Denver. These activities are detailed in the report.

Mason, Larry W.

1997-01-01

81

Study on effect of annealing conditions on structural, magnetic and superconducting properties of MgB2 bulk samples  

NASA Astrophysics Data System (ADS)

Effect of annealing conditions on structural, magnetic and superconducting properties of Magnesium Diboride (MgB2) bulk superconductor samples prepared by solid state route method are compared. The samples are made by taking Magnesium and Boron powders in stoichiometric ratio, grounded well and pelletized at pressure of about 10Tonnes. These pellets are annealed in both Argon and vacuum environment separately up to 800°c for two hours. Both the samples show clear superconducting transition at Tc ˜ 38 k. This is further conformed by AC/DC magnetization (M-T), Resistivity [? (T, H)] measurements under magnetic field up to 14 Tesla as well. Rietveld refinement of X-ray diffraction of both samples conformed the MgB2 phase formation with P6/mmm space group symmetry. Scanning Electron Microscopy images of the surface revile more agglomeration of grains in case of Argon annealed samples. This result in more critical current density (Jc) of Argon annealed samples than vacuum annealed one calculated from Bean's critical state model. This high Jc is explained in terms of more inter grain connectivity for Argon annealed sample than vacuum annealed sample.

Phaneendra, Konduru; Asokan, K.; Awana, V. P. S.; Sastry, S. Sreehari; Kanjilal, D.

2014-04-01

82

Study on effect of annealing conditions on structural, magnetic and superconducting properties of MgB{sub 2} bulk samples  

SciTech Connect

Effect of annealing conditions on structural, magnetic and superconducting properties of Magnesium Diboride (MgB{sub 2}) bulk superconductor samples prepared by solid state route method are compared. The samples are made by taking Magnesium and Boron powders in stoichiometric ratio, grounded well and pelletized at pressure of about 10Tonnes. These pellets are annealed in both Argon and vacuum environment separately up to 800°c for two hours. Both the samples show clear superconducting transition at Tc ? 38 k. This is further conformed by AC/DC magnetization (M-T), Resistivity [? (T, H)] measurements under magnetic field up to 14 Tesla as well. Rietveld refinement of X-ray diffraction of both samples conformed the MgB{sub 2} phase formation with P6/mmm space group symmetry. Scanning Electron Microscopy images of the surface revile more agglomeration of grains in case of Argon annealed samples. This result in more critical current density (J{sub c}) of Argon annealed samples than vacuum annealed one calculated from Bean's critical state model. This high Jc is explained in terms of more inter grain connectivity for Argon annealed sample than vacuum annealed sample.

Phaneendra, Konduru, E-mail: phaneendra-50@yahoo.com; Asokan, K., E-mail: phaneendra-50@yahoo.com; Kanjilal, D. [Inter University Accelerator Centre, Aruna Asaf Ali Marg, Vasanth Kung, New Delhi-110067 (India); Awana, V. P. S. [Quantum Phenomena and Applications, National Physical Laboratory, K S Krishnan Marg, New Delhi-110012 (India); Sastry, S. Sreehari [Dept. of Physics, Acharya Nagarjuna University, Guntur-522510 (India)

2014-04-24

83

Radiation hard vacuum switch  

DOEpatents

A vacuum switch with an isolated trigger probe which is not directly connected to the switching electrodes. The vacuum switch within the plasmatron is triggered by plasma expansion initiated by the trigger probe which travels through an opening to reach the vacuum switch elements. The plasma arc created is directed by the opening to the space between the anode and cathode of the vacuum switch to cause conduction.

Boettcher, Gordon E. (Albuquerque, NM)

1990-01-01

84

The Classical Vacuum.  

ERIC Educational Resources Information Center

The classical vacuum of physics is not empty, but contains a distinctive pattern of electromagnetic fields. Discovery of the vacuum, thermal spectrum, classical electron theory, zero-point spectrum, and effects of acceleration are discussed. Connection between thermal radiation and the classical vacuum reveals unexpected unity in the laws of…

Boyer, Timothy H.

1985-01-01

85

Wolf-Rayet phenomena  

NASA Technical Reports Server (NTRS)

The properties of stars showing Wolf-Rayet phenomena are outlined along with the direction of future work. Emphasis is placed on the characteristics of W-R spectra. Specifically the following topics are covered: the absolute visual magnitudes; the heterogeneity of WN spectra; the existence of transition type spectra and compositions the mass loss rates; and the existence of very luminous and possibly very massive W-R stars. Also, a brief overview of current understanding of the theoretical aspects of stellar evolution and stellar winds and the various scenarios that have been proposed to understand W-R spectra are included.

Conti, P. S.

1982-01-01

86

High power, high frequency, vacuum flange  

DOEpatents

An improved waveguide flange is disclosed for high power operation that helps prevent arcs from being initiated at the junctions between waveguide sections. The flanges at the end of the waveguide sections have counter bores surrounding the waveguide tubes. When the sections are bolted together the counter bores form a groove that holds a fully annealed copper gasket. Each counterbore has a beveled step that is specially configured to insure the gasket forms a metal-to-metal vacuum seal without gaps or sharp edges. The resultant inner surface of the waveguide is smooth across the junctions between waveguide sections, and arcing is prevented.

Felker, B.; McDaniel, M.R.

1993-03-23

87

Indium out-diffusion in Al{sub 2}O{sub 3}/InGaAs stacks during anneal at different ambient conditions  

SciTech Connect

Indium out-diffusion during anneal enhances leakage currents in metal/dielectric/InGaAs gate stacks. In this work, we study the influence of ambient conditions during anneal on indium out-diffusion in Al{sub 2}O{sub 3}/InGaAs structures, prior to the gate metal deposition. Using X-ray photoemission spectroscopy and time of flight secondary ions mass spectrometry, we observed much lower indium concentrations in the Al{sub 2}O{sub 3} layer following vacuum and O{sub 2} anneals compared to forming gas or nitrogen anneals. The electrical characteristics of the Ni/Al{sub 2}O{sub 3}/InGaAs gate stack following these pre-metallization anneals as well as after subsequent post metallization anneals are presented. Possible explanations for the role of the annealing ambient conditions on indium out-diffusion are presented.

Krylov, Igor, E-mail: krylov@tx.technion.ac.il [The Russell Berrie Nanotechnology Institute, Technion–Israel Institute of Technology, Haifa 32000 (Israel); Winter, Roy [Department of Materials Science and Engineering, Technion–Israel Institute of Technology, Haifa 32000 (Israel); Ritter, Dan [The Russell Berrie Nanotechnology Institute, Technion–Israel Institute of Technology, Haifa 32000 (Israel); Department of Electrical Engineering, Technion–Israel Institute of Technology, Haifa 32000 (Israel); Eizenberg, Moshe [The Russell Berrie Nanotechnology Institute, Technion–Israel Institute of Technology, Haifa 32000 (Israel); Department of Materials Science and Engineering, Technion–Israel Institute of Technology, Haifa 32000 (Israel)

2014-06-16

88

MULTISCALE PHENOMENA IN MATERIALS  

SciTech Connect

This project developed and supported a technology base in nonequilibrium phenomena underpinning fundamental issues in condensed matter and materials science, and applied this technology to selected problems. In this way the increasingly sophisticated synthesis and characterization available for classes of complex electronic and structural materials provided a testbed for nonlinear science, while nonlinear and nonequilibrium techniques helped advance our understanding of the scientific principles underlying the control of material microstructure, their evolution, fundamental to macroscopic functionalities. The project focused on overlapping areas of emerging thrusts and programs in the Los Alamos materials community for which nonlinear and nonequilibrium approaches will have decisive roles and where productive teamwork among elements of modeling, simulations, synthesis, characterization and applications could be anticipated--particularly multiscale and nonequilibrium phenomena, and complex matter in and between fields of soft, hard and biomimetic materials. Principal topics were: (i) Complex organic and inorganic electronic materials, including hard, soft and biomimetic materials, self-assembly processes and photophysics; (ii) Microstructure and evolution in multiscale and hierarchical materials, including dynamic fracture and friction, dislocation and large-scale deformation, metastability, and inhomogeneity; and (iii) Equilibrium and nonequilibrium phases and phase transformations, emphasizing competing interactions, frustration, landscapes, glassy and stochastic dynamics, and energy focusing.

A. BISHOP

2000-09-01

89

Fog phenomena on Mars  

NASA Astrophysics Data System (ADS)

Mars Express High Resolution Stereo Camera (HRSC) images show impressive morning fog features in Valles Marineris and other regions of the surface of Mars. Temperatures have been determined, simultaneously to the imaging, by Mars Express Planetary Fourier Spectrometer (PFS). This identifies water ice rather than frozen CO 2 as the cause of the fog observations in Valles Marineris. Numerical estimates of the water vapor pressure, and the related atmospheric water content, at the frost-point (temperature of freezing or "re-sublimation" of water vapor) by a 1-dimensional planetary boundary layer model indicate that conditions in the planetary boundary layer can indeed temporarily favor the formation of ice particles. A systematic registration of sites of fog observations shows preferred regions and seasons on Mars for fog phenomena. In the first instance, the fog phenomena seem to be induced or supported by orographic effects but not directly by the distribution pattern of the atmospheric vapor or by the regional subsurface water content. This paper documents and thermodynamically verifies the existence of fog of water ice particles in the near-surface atmosphere of Mars.

Möhlmann, Diedrich T. F.; Niemand, Monika; Formisano, Vittorio; Savijärvi, Hannu; Wolkenberg, Paulina

2009-12-01

90

Radiation damage and annealing of amorphous silicon solar cells  

NASA Technical Reports Server (NTRS)

Amorphous silicon solar cells were irradiated with 1 MeV electrons at the Space Environmental Effects Laboratory of the NASA Langley Research Center. The cells accumulated a total fluence of 10 to the 14th, 10 to the 15th, and 10 to the 16th electrons per square centimeter and exhibited increasing degradation with each irradiation. This degradation was tracked by evaluating the I-V curves for AM0 illumination and the relative spectral response. The observed radiation damage was reversed following an anneal of the cells under vacuum at 200 C for 2 hours.

Byvik, C. E.; Slemp, W. S.; Smith, B. T.; Buoncristiani, A. M.

1984-01-01

91

Atomic-scale investigation of graphene grown on Cu foil and the effects of thermal annealing.  

SciTech Connect

We have investigated the effects of thermal annealing on ex-situ chemically vapor deposited submonolayer graphene islands on polycrystalline Cu foil at the atomic-scale using ultrahigh vacuum scanning tunneling microscopy. Low-temperature annealed graphene islands on Cu foil (at 430 C) exhibit predominantly striped Moir patterns, indicating a relatively weak interaction between graphene and the underlying polycrystalline Cu foil. Rapid high-temperature annealing of the sample (at 700-800 C) gives rise to the removal of Cu oxide and the recovery of crystallographic features of the copper that surrounds the intact graphene. These experimental observations of continuous crystalline features between the underlying copper (beneath the graphene islands) and the surrounding exposed copper areas revealed by high-temperature annealing demonstrates the impenetrable nature of graphene and its potential application as a protective layer against corrosion.

Cho, J. W.; Gao, L.; Tian, J.; Cao, H.; Wu, W.; Yu, Q.; Yitamben, E. N.; Fisher, B.; Guest, J. R.; Chen, Y. P.; Guisinger, N. P. (Center for Nanoscale Materials); (Purdue Univ.); (Univ. of Houston)

2011-05-01

92

Breakdown phenomena in high power klystrons  

NASA Astrophysics Data System (ADS)

In the course of developing new high peak power klystrons at SLAC, high electric fields in several regions of these devices have become an important source of vacuum breakdown phenomena. In addition, a renewed interest in breakdown phenomena for nanosecond pulse, multi-megavolt per centimeter fields has been sparked by recent R and D work in the area of gigawatt RF sources. The most important regions of electrical breakdown are in the output cavity gap area, the RF ceramic windows, and the gun ceramic insulator. The details of the observed breakdown in these regions, experiments performed to understand the phenomena and solutions found to alleviate the problems will be discussed. Recently experiments have been performed on a new prototype R and D klystron. Peak electric fields across the output cavity gaps of this klystron exceed 2 MV/cm. The effect of peak field duration (i.e., pulse width) on the onset of breakdown have been measured. The pulse widths varied from tens of nanoseconds to microseconds. Results from these experiments will be presented. The failure of ceramic RF windows due to multipactor and puncturing was an important problem to overcome in order that our high power klystrons would have a useful life expectancy. Consequently many studies and tests were made to understand and alleviate window breakdown phenomena. Some of the results in this area, especially the effects of surface coatings, window materials and processing techniques and their effects on breakdown will be discussed. Another important source of klystron failure in the recent past at SLAC has been the puncturing of the high voltage ceramic insulator in the gun region. A way of alleviating this problem has been found although the actual cause of the puncturing is not yet clear. The practical solution to this breakdown process will be described and a possible mechanism for the puncturing will be presented.

Vlieks, A. E.; Allen, M. A.; Callin, R. S.; Fowkes, W. R.; Hoyt, E. W.; Lebacqz, J. V.; Lee, T. G.

1988-03-01

93

Weld pool phenomena  

SciTech Connect

During welding, the composition, structure and properties of the welded structure are affected by the interaction of the heat source with the metal. The interaction affects the fluid flow, heat transfer and mass transfer in the weld pool, and the solidification behavior of the weld metal. In recent years, there has been a growing recognition of the importance of the weld pool transport processes and the solid state transformation reactions in determining the composition, structure and properties of the welded structure. The relation between the weld pool transport processes and the composition and structure is reviewed. Recent applications of various solidification theories to welding are examined to understand the special problems of weld metal solidification. The discussion is focussed on the important problems and issues related to weld pool transport phenomena and solidification. Resolution of these problems would be an important step towards a science based control of composition, structure and properties of the weld metal.

David, S.A.; Vitek, J.M.; Zacharia, T. [Oak Ridge National Lab., TN (United States); DebRoy, T. [Pennsylvania State Univ., University Park, PA (United States)

1994-09-01

94

Attoheat transport phenomena  

E-print Network

Fascinating developments in optical pulse engineering over the last 20 years lead to the generation of laser pulses as short as few femtosecond, providing a unique tool for high resolution time domain spectroscopy. However, a number of the processes in nature evolve with characteristic times of the order of 1 fs or even shorter. Time domain studies of such processes require at first place sub-fs resolution, offered by pulse depicting attosecond localization. The generation, characterization and proof of principle applications of such pulses is the target of the attoscience. In the paper the thermal processes on the attosecond scale are described. The Klein-Gordon and Proca equations are developed. The relativistic effects in the heat transport on nanoscale are discussed. It is shown that the standard Fourier equation can not be valid for the transport phenomena induced by attosecond laser pulses. The heat transport in nanoparticles and nanotubules is investigated.

J. Marciak-Kozlowska; M. Pelc; M. A. Kozlowski

2009-06-09

95

Transport phenomena in nanofluidics  

NASA Astrophysics Data System (ADS)

The transport of fluid in and around nanometer-sized objects with at least one characteristic dimension below 100nm enables the occurrence of phenomena that are impossible at bigger length scales. This research field was only recently termed nanofluidics, but it has deep roots in science and technology. Nanofluidics has experienced considerable growth in recent years, as is confirmed by significant scientific and practical achievements. This review focuses on the physical properties and operational mechanisms of the most common structures, such as nanometer-sized openings and nanowires in solution on a chip. Since the surface-to-volume ratio increases with miniaturization, this ratio is high in nanochannels, resulting in surface-charge-governed transport, which allows ion separation and is described by a comprehensive electrokinetic theory. The charge selectivity is most pronounced if the Debye screening length is comparable to the smallest dimension of the nanochannel cross section, leading to a predominantly counterion containing nanometer-sized aperture. These unique properties contribute to the charge-based partitioning of biomolecules at the microchannel-nanochannel interface. Additionally, at this free-energy barrier, size-based partitioning can be achieved when biomolecules and nanoconstrictions have similar dimensions. Furthermore, nanopores and nanowires are rooted in interesting physical concepts, and since these structures demonstrate sensitive, label-free, and real-time electrical detection of biomolecules, the technologies hold great promise for the life sciences. The purpose of this review is to describe physical mechanisms on the nanometer scale where new phenomena occur, in order to exploit these unique properties and realize integrated sample preparation and analysis systems.

Schoch, Reto B.; Han, Jongyoon; Renaud, Philippe

2008-07-01

96

An Introduction to Simulated Annealing  

ERIC Educational Resources Information Center

An attempt to model the physical process of annealing lead to the development of a type of combinatorial optimization algorithm that takes on the problem of getting trapped in a local minimum. The author presents a Microsoft Excel spreadsheet that illustrates how this works.

Albright, Brian

2007-01-01

97

Genetic algorithms and simulated annealing  

Microsoft Academic Search

This RESEARCH NOTE is a collection of papers on two types of stochastic search techniques-genetic algorithms and simulated annealing. These two techniques have been applied to problems that are both difficult and important, such as designing semiconductor layouts, controlling factories, and making communication networks cheaper, to name a few. Both techniques are modeled on processes found in nature-natural evolution and

Lawrence Davis

1987-01-01

98

Vacuum pump aids ejectors  

SciTech Connect

The steam ejector/vacuum pump hybrid system has been operating satisfactorily since the summer of 1981. This system has essentially been as troublefree as the all-ejector system and, of course, has provided a substantial cost savings. Construction is currently under way to convert the vacuum system of another crude still which is equipped with steam ejectors and barometric condensers to the hybrid system of steam ejectors, surface condensers, and vacuum pumps. This current project is even more financially attractive because it allows a dirty water cooling tower which serves the barometric condensers to be shut down. Providing a vacuum for crude distillation vacuum towers with this hybrid system is by no means the only application of this technique. Any vacuum system consisting of all steam ejectors would be a candidate for this hybrid system and the resulting savings in energy.

Nelson, R.E.

1982-12-01

99

Enhancement in visible luminescence from nanocomposite ZnO-SiOx thin films due to annealing  

NASA Astrophysics Data System (ADS)

The annealing induced enhancement in visible photoluminescence (PL) from nanocomposite (nc) ZnO-SiOx thin films was investigated. Nc ZnO-SiOx thin films consisting of ZnO nanocrystals in silica matrix were grown by depositing the films using radio frequency (rf) reactive co-sputtering and post-annealing them at temperatures of 350°C and 500°C in high vacuum and air. These films were characterized by Fourier transform infrared (FTIR), (PL) spectroscopy and UV-Vis spectrophotometry measurements. Thin films were also deposited on transmission electron microscopy (TEM) grids in almost identical conditions. The TEM measurement of the thin film deposited on TEM grid shows the formation of ZnO nanocrystals with a size distribution from 3.0 nm to 6.8 nm (+/-0.2 nm) in silica matrix. The UV-Vis spectra of the films show absorption features of ZnO and Zn2SiO4 phases in the films. The visible PL emission intensity and peak width increased in the annealed films. The results suggest increase in the number and size distribution of the ZnO nanocrystals in silica matrix due to the annealing resulting in increase in visible PL emission. The results of vacuum annealed films indicate that these films can be useful in the development of wide band visible light emitting devices using this material.

Kumar, V. V. Siva; Kanjilal, D.

2014-01-01

100

Vacuum probe surface sampler  

NASA Technical Reports Server (NTRS)

A vacuum probe surface sampler is described for rapidly sampling relatively large surface areas which possess relatively light loading densities of micro-organism, drug particles or the like. A vacuum head with a hollow handle connected to a suitable vacuum source is frictionally attached to a cone assembly terminating in a flared tip adapted to be passed over the surface to be sampled. A fine mesh screen carried by the vacuum head provides support for a membrane filter which collects the microorganisms or other particles. The head assembly is easily removed from the cone assembly without contacting the cone assembly with human hands.

Zahlava, B. A. (inventor)

1973-01-01

101

NSLS II Vacuum System  

SciTech Connect

National Synchrotron Light Source II, being constructed at Brookhaven, is a 3-GeV, 500 mA, 3rd generation synchrotron radiation facility with ultra low emittance electron beams. The storage ring vacuum system has a circumference of 792 m and consists of over 250 vacuum chambers with a simulated average operating pressure of less than 1 x 10{sup -9} mbar. A summary of the update design of the vacuum system including girder supports of the chambers, gauges, vacuum pumps, bellows, beam position monitors and simulation of the average pressure will be shown. A brief description of the techniques and procedures for cleaning and mounting the chambers are given.

Ferreira, M.; Doom, L.; Hseuh, H.; Longo, C.; Settepani, P.; Wilson, K.; Hu, J.

2009-09-13

102

Arcjet Cathode Phenomena  

NASA Technical Reports Server (NTRS)

Cathode tips made from a number of different materials were tested in a modular arcjet thruster in order to examine cathode phenomena. Periodic disassembly and examination, along with the data collected during testing, indicated that all of the tungsten-based materials behaved similarly despite the fact that in one of these samples the percentage of thorium oxide was doubled and another was 25 percent rhenium. The mass loss rate from a 2 percent thoriated rhenium cathode was found to be an order of magnitude greater than that observed using 2 percent thoriated tungsten. Detailed analysis of one of these cathode tips showed that the molten crater contained pure tungsten to a depth of about 150 microns. Problems with thermal stress cracking were encountered in the testing of a hafnium carbide tip. Post test analysis showed that the active area of the tip had chemically reacted with the propellant. A 100 hour continuous test was run at about 1 kW. Post test analysis revealed no dendrite formation, such as observed in a 30 kW arcjet lifetest, near the cathode crater. The cathodes from both this test and a previously run 1000 hour cycled test displayed nearly identical arc craters. Data and calculations indicate that the mass losses observed in testing can be explained by evaporation.

Curran, Francis M.; Haag, Thomas W.; Raquet, John F.

1989-01-01

103

Arcjet cathode phenomena  

NASA Technical Reports Server (NTRS)

Cathode tips made from a number of different materials were tested in a modular arcjet thruster in order to examine cathode phenomena. Periodic disassembly and examination, along with the data collected during testing, indicated that all of the tungsten-based materials behaved similarly despite the fact that in one of these samples the percentage of thorium oxide was doubled and another was 25 percent rhenium. The mass loss rate from a 2 percent thoriated rhenium cathode was found to be an order of magnitude greater than that observed using 2 percent thoriated tungsten. Detailed analysis of one of these cathode tips showed that the molten crater contained pure tungsten to a depth of about 150 microns. Problems with thermal stress cracking were encountered in the testing of a hafnium carbide tip. Post test analysis showed that the active area of the tip had chemically reacted with the propellant. A 100 hour continuous test was run at about 1 kW. Post test analysis revealed no dendrite formation, such as observed in a 30 kW arcjet lifetest, near the cathode crater. The cathodes from both this test and a previously run 1000 hour cycled test displayed nearly identical arc craters. Data and calculations indicate that the mass losses observed in testing can be explained by evaporation.

Curran, Francis M.; Haag, Thomas W.; Raquet, John F.

1989-01-01

104

Efficient Simulated Annealing on Fractal Energy Landscapes  

Microsoft Academic Search

We present a new theoretical framework for analyzing simulated annealing. The behavior of simulated annealing depends crucially\\u000a on the ld?ergy landscape” associated with the optimization problem: the landscape must have special properties if annealing\\u000a is to be efficient.\\u000a \\u000a We prove that certain fractal properties are sufficient for simulated annealing to be efficient in the following sense: If\\u000a a problem is

Gregory B. Sorkin

1991-01-01

105

In situ laser annealing system for real-time surface kinetic analysis  

NASA Astrophysics Data System (ADS)

For real-time analysis during thermal annealing, a continuous wave CO2 infrared laser was coupled to a surface analysis system equipped for x-ray photoelectron spectroscopy (XPS) and ion scattering spectroscopy (ISS). The laser beam was directed into the vacuum chamber through a ZnSe window to the back side of the sample. With 10 W laser output, the sample temperature reached 563 K. The chamber remained below 10-8 Torr during annealing and allowed XPS and ISS data to be gathered as a function of time at selected temperatures. As a test example, real time Cu2O reduction at 563 K was investigated.

Wang, Q.; Sun, Y.-M.; Zhao, W.; Campagna, J.; White, J. M.

2002-11-01

106

FREEZE-FRACTURIN G IN ULTRAHIGH VACUUM AT -196  

Microsoft Academic Search

Conventional freeze-etching is carried out in a vacuum of -10 -~ torr and at a specimen temperature of -100~ The relatively poor topographic resolution of most freeze-etch replicas, and the lack of complementarity of morphological details in double replicas have been thought to be caused by structural distortions during fracturing, and radiation damage during replication. Both phenomena can be reduced

HEINZ GROSS; ENIS BAS; HANS MOOR

107

Effect of parallel circuit parameters on the instability of a low-current vacuum arc  

Microsoft Academic Search

To clarify the instability phenomena of a low-current vacuum arc, we observe the phenomena by changing the parallel circuit parameters. We measure instability-initiation current, chopping current, arc voltage, reignition voltage peak, and the transient recovery voltage by using copper, copper chromium, copper tungsten, and silver tungsten carbide electrodes. We find that the chopping current, reignition voltage peak, and transient recovery

Cuie Ding; Satoru Yanabu

2003-01-01

108

Vacuum Vessel Remote Handling  

E-print Network

FIRE Vacuum Vessel and Remote Handling Overview B. Nelson, T. Burgess, T. Brown, H-M Fan, G. Jones · Vacuum Vessel - Design requirements - Design concept and features - Analysis to date - Status and summary Replacement Time Estimates - Balance of RH Equipment · Design and analysis are consistent with pre

109

The ultimate vacuum  

Microsoft Academic Search

The ultimate vacuum, defined as the lowest pressure that can be produced and measured reproducibly in a vacuum system at room temperature, has decreased by a factor of about 1014 since the first measurement of sub-atmospheric pressure by Robert Boyle in about 1660. A brief historical review is presented of the key advances that caused significant decreases in the ultimate

P. A. Redhead

1999-01-01

110

Microfabricated triggered vacuum switch  

DOEpatents

A microfabricated vacuum switch is disclosed which includes a substrate upon which an anode, cathode and trigger electrode are located. A cover is sealed over the substrate under vacuum to complete the vacuum switch. In some embodiments of the present invention, a metal cover can be used in place of the trigger electrode on the substrate. Materials used for the vacuum switch are compatible with high vacuum, relatively high temperature processing. These materials include molybdenum, niobium, copper, tungsten, aluminum and alloys thereof for the anode and cathode. Carbon in the form of graphitic carbon, a diamond-like material, or carbon nanotubes can be used in the trigger electrode. Channels can be optionally formed in the substrate to mitigate against surface breakdown.

Roesler, Alexander W. (Tijeras, NM); Schare, Joshua M. (Albuquerque, NM); Bunch, Kyle (Albuquerque, NM)

2010-05-11

111

ELETTRA vacuum system  

NASA Astrophysics Data System (ADS)

A status report of the vacuum system of ELETTRA, the 2 GeV, 400 mA light source under construction in Trieste, will be described. The Vacuum project, presented at ``Synchrotron Radiation Vacuum Workshop'' at Riken (Japan 22-24 March 1990) and more recently at EVC-2, the European Vacuum Conference at Trieste (Italy 21-26 May 1990), is now in the phase of testing a prototype sector, which is 1/24 of the ring circumference. Details and some technological aspects of the fabrication will be reviewed together with the vacuum performances. Results of laboratory experiments on components, standard or not, allowed us to finalize the main choices in light of the general philosophy of the project and will be properly summarized.

Bernardini, M.

1991-08-01

112

Typewriter Keyboards via Simulated Annealing  

Microsoft Academic Search

We apply the simulated annealing algorithmto the combinatorial optimization problem oftypewriter keyboard design, yielding nearlyoptimal key-placements using a figure of meritbased on English letter pair frequencies andfinger travel-times. Our keyboards are demonstrablysuperior to both the ubiquitous QWERTYkeyboard and the less common Dvorakkeyboard.The paper is constructed as follows: firstwe discuss the historical background of keyboarddesign; this includes August Dvorak'swork,...

Lissa W. Light; Peter G. Anderson

1993-01-01

113

The evolution of the structure and mechanical properties of fullerenelike hydrogenated amorphous carbon films upon annealing  

SciTech Connect

Hydrogenated amorphous carbon films were deposited on Si (100) substrates using dc-pulse plasma chemical vapor deposition. Structurally, the as-deposited carbon films could be considered as nanocomposite thin films with fullerenelike microstructure in diamondlike carbon matrix based on our previous result [Q. Wang et al., Appl. Phys. Lett. 91, 141902 (2007)]. In this paper, the evolution of the structure and the mechanical properties of hydrogenated carbon films with fullerenelike microstructure on the annealing in vacuum was investigated. The fullerenelike hydrogenated carbon films annealed at 500 deg. C showed higher hardness (16.9% harder) and higher elastic recovery (11.2% higher) than the as-deposited films. The friction coefficient of fullerenelike hydrogenated carbon films in air with 40% relative humidity remained constant at about 0.037 when annealed at 600 deg. C. The wear rate of the films decreased sharply when annealed at 200 or 300 deg. C. Structural analysis shows that annealing at 300 deg. C improved tribological properties originated from the volume increase in the fullerenelike microstructure, and further annealing at 600 deg. C improved mechanical properties originated from the transformation of nanosized curved sp{sup 2} to sp{sup 3} clusters.

Wang Qi [Department of Physics, Lanzhou University, Lanzhou 730000 (China); State Key Laboratory of Solid Lubrication, Lanzhou Institute of Chemical Physics, Chinese Academy of Sciences, Lanzhou 730000 (China); He Deyan [Department of Physics, Lanzhou University, Lanzhou 730000 (China); Wang Chengbing; Wang Zhou; Zhang Junyan [State Key Laboratory of Solid Lubrication, Lanzhou Institute of Chemical Physics, Chinese Academy of Sciences, Lanzhou 730000 (China)

2008-08-15

114

Mathematical methods of studying physical phenomena  

NASA Astrophysics Data System (ADS)

In recent decades, substantial theoretical and experimental progress was achieved in understanding the quantum nature of physical phenomena that serves as the foundation of present and future quantum technologies. Quantum correlations like the entanglement of the states of composite systems, the phenomenon of quantum discord, which captures other aspects of quantum correlations, quantum contextuality and, connected with these phenomena, uncertainty relations for conjugate variables and entropies, like Shannon and Rényi entropies, and the inequalities for spin states, like Bell inequalities, reflect the recently understood quantum properties of micro and macro systems. The mathematical methods needed to describe all quantum phenomena mentioned above were also the subject of intense studies in the end of the last, and beginning of the new, century. In this section of CAMOP 'Mathematical Methods of Studying Physical Phenomena' new results and new trends in the rapidly developing domain of quantum (and classical) physics are presented. Among the particular topics under discussion there are some reviews on the problems of dynamical invariants and their relations with symmetries of the physical systems. In fact, this is a very old problem of both classical and quantum systems, e.g. the systems of parametric oscillators with time-dependent parameters, like Ermakov systems, which have specific constants of motion depending linearly or quadratically on the oscillator positions and momenta. Such dynamical invariants play an important role in studying the dynamical Casimir effect, the essence of the effect being the creation of photons from the vacuum in a cavity with moving boundaries due to the presence of purely quantum fluctuations of the electromagnetic field in the vacuum. It is remarkable that this effect was recently observed experimentally. The other new direction in developing the mathematical approach in physics is quantum tomography that provides a new vision of quantum states. In the tomographic picture of quantum mechanics, the states are identified with fair conditional probability distributions, which contain the same information on the states as the wave function or the density matrix. The mathematical methods of the tomographic approach are based on studying the star-product (associative product) quantization scheme. The tomographic star-product technique provides an additional understanding of the associative product, which is connected with the existence of specific pairs of operators called quantizers and dequantizers. These operators code information on the kernels of all the star-product schemes, including the traditional phase-space Weyl-Wigner-Moyal picture describing the quantum-system evolution. The new equation to find quantizers, if the kernel of the star product of functions is given, is presented in this CAMOP section. For studying classical systems, the mathematical methods developed in quantum mechanics can also be used. The case of paraxial-radiation beams propagating in waveguides is a known example of describing a purely classical phenomenon by means of quantum-like equations. Thus, some quantum phenomenon like the entanglement can be mimicked by the properties of classical beams, for example, Gaussian modes. The mathematical structures and relations to the symplectic symmetry group are analogous for both classical and quantum phenomena. Such analogies of the mathematical classical and quantum methods used in research on quantum-like communication channels provide new tools for constructing a theoretical basis of the new information-transmission technologies. The conventional quantum mechanics and its relation to classical mechanics contain mathematical recipes of the correspondence principle and quantization rules. Attempts to find rules for deriving the quantum-mechanical formalism starting from the classical field theory, taking into account the influence of classical fluctuations of the field, is considered in these papers. The methods to solve quantum equations and formulate the boundary co

Man'ko, Margarita A.

2013-03-01

115

Surface characteristics of boron-doped diamond exposed to high-temperature annealing: Effect of hydrogen atmosphere  

E-print Network

Surface characteristics of boron-doped diamond exposed to high-temperature annealing: Effect at the same temperature in high vacuum for 5 hours and analyzed. Surface analysis by X-ray photoelectron of energy-distributed electronic states, as revealed by AC-impedance spectroscopy in 0.1M H2SO4 electrolyte

Pfeifer, Holger

116

Evading death by vacuum  

NASA Astrophysics Data System (ADS)

In the Standard Model, the Higgs potential allows only one minimum at tree level. But the open possibility that there might be two scalar doublets enriches the vacuum structure, allowing for the risk that we might now be in a metastable state, which we dub the panic vacuum. Current experiments at the LHC are probing the Higgs particle predicted as a result of the spontaneous symmetry breaking. Remarkably, in the two Higgs model with a softly broken U(1) symmetry, the LHC experiments already allow to exclude many panic vacuum solutions.

Barroso, A.; Ferreira, P. M.; Ivanov, I. P.; Santos, Rui; Silva, João P.

2013-09-01

117

Evading death by vacuum  

E-print Network

In the Standard Model, the Higgs potential allows only one minimum at tree-level. But the open possibility that there might be two scalar doublets enriches the vacuum structure, allowing for the risk that we might now be in a metastable state, which we dub the panic vacuum. Current experiments at the LHC are probing the Higgs particle predicted as a result of the spontaneous symmetry breaking. Remarkably, in the two Higgs model with a softly broken U(1) symmetry, the LHC experiments already preclude panic vacuum solutions.

A. Barroso; P. M. Ferreira; I. P. Ivanov; Rui Santos; João P. Silva

2012-11-26

118

Improvement in the electrical properties of Se- and S-doped hydrogenated amorphous silicon thin films by annealing  

NASA Astrophysics Data System (ADS)

We studied the effect of annealing on the dark and photo conductivity of Se- and S-doped hydrogenated amorphous silicon (a-Si:H) thin films. The films were prepared on corning glass by using conventional plasma-enhanced chemical vapor deposition (PE-CVD). The samples were subsequently annealed in a vacuum (1 × 10-6Torr) at an annealing temperature of 300 °C for an hour. The conductivity was measured in the temperature range of 300-470 K, which exhibited two different transport mechanisms. In the high-temperature range (370-470 K), the conduction was found to be an activated type while in the low-temperature range (less than 370 K), it was observed to follow variable range hopping. Arrhenius plots of the conductivities for S- and Se-doped a-Si:H films revealed that the activation energy was lower after annealing, owing to the removal of the surface defects created during deposition. The characteristic energy, E MN, was lower in the annealed films for both types of dopant concentrations, which suggests a reduction in the number of traps. The photoconductivity was increased by vacuum annealing at 300 °C by a factor of more than 10.

Sharma, S. K.; Kim, Deuk Young; Mehra, R. M.

2013-05-01

119

The effects of deposition and annealing conditions on crystallographic properties of sputtered barium ferrite thick films  

Microsoft Academic Search

The development of devices combining a ferrite with a semiconductor chip is a major focus of current research and could make use of vacuum deposition techniques of magnetic films. Barium hexaferrite (BaFe12O19; BaM) thick films are deposited here using an rf non-reactive sputtering system. Because the as-deposited films are amorphous and non-magnetic, two kinds of post-deposition annealing are employed, which

B. Bayard; J. P. Chatelon; M. Le Berre; H. Joisten; J. J. Rousseau; Barbier

2002-01-01

120

Vacuum Camera Cooler  

NASA Technical Reports Server (NTRS)

Acquiring cheap, moving video was impossible in a vacuum environment, due to camera overheating. This overheating is brought on by the lack of cooling media in vacuum. A water-jacketed camera cooler enclosure machined and assembled from copper plate and tube has been developed. The camera cooler (see figure) is cup-shaped and cooled by circulating water or nitrogen gas through copper tubing. The camera, a store-bought "spy type," is not designed to work in a vacuum. With some modifications the unit can be thermally connected when mounted in the cup portion of the camera cooler. The thermal conductivity is provided by copper tape between parts of the camera and the cooled enclosure. During initial testing of the demonstration unit, the camera cooler kept the CPU (central processing unit) of this video camera at operating temperature. This development allowed video recording of an in-progress test, within a vacuum environment.

Laugen, Geoffrey A.

2011-01-01

121

Pumpdown and Vacuum Pumps  

NSDL National Science Digital Library

This is a link to a PDF version of lecture slides that discuss vacuum pumpdown. Graphics are included which depict pumpdown procedure, venting procedure, pressure curves and system pumpdown. Keywords: Outgassing, pressure range, rotary vane, rotary piston, roots blower

Rack, Philip D.

122

Schizoid phenomena in substance abusers.  

PubMed

It is hypothesized that the spectrum of schizoid disorders, schizoid phenomena, and the underlying psychodynamics can often be found in the gamut of addictions and stand in the way of recovery. Features of schizoidness, the varieties of schizoid presentations, the etiology and pathogenesis of drug/alcohol abuse in the schizoid, and readily clinically apparent psychodynamic features are discussed. Schizoid phenomena can be dealt with effectively with an informed psychotherapy. PMID:12095001

Armstrong, Ralph H

2002-01-01

123

Conductive layers in diamond formed by hydrogen ion implantation and annealing  

NASA Astrophysics Data System (ADS)

High conductivity is extremely difficult to obtain in diamond due to its wide band gap and low solubility of dopands. The goal of the investigation was to form a conductor inside HPHT synthetic diamond plates with initial high sheet resistivity ?s (˜1012 ?/sq) for 400 ?m thickness. We used metastable character of diamond structures relative to the graphitization of defective layers formed by 50 keV hydrogen molecular ions at high fluence ? = (1-13) × 1016 cm-2 ion implantation. High temperature (HT) (500-1600 °C) and vacuum or high pressure (VP/HP) (3 × 10-3/4 × 109 Pa) thermal annealing were chosen to provide the annealing regimes where the graphitic carbon is the most stable phase. Sheet resistance, dropped down up to nine orders of magnitude (?s ˜ 103 ?/sq), as well as Raman spectroscopy, and AFM measurements were used to determine electrical, optical and geometrical properties of multilayered heterostructures formed in the set of experiments. Temperature dependences of the conductivity show, that after highest fluencies and annealing temperatures the conductivity is quasimetallic and electronic system is above metal-insulator transition (MIT). At lower fluences and/or annealing temperatures the system is under MIT with the transport of charge carriers being well described by variable range hopping (VRH) mechanism with variable decay length of wave function for localized states. Two or three order of magnitude differences in the conductivity in VP and HP annealed samples are attributed with the higher dimensions of graphite nanocrystals in the case of vacuum annealing. This suggestion coincides with Raman spectra and optimum hopping length for carrier jumps in VRH model for conductivity in the buried layers.

Popov, V. P.; Safronov, L. N.; Naumova, O. V.; Nikolaev, D. V.; Kupriyanov, I. N.; Palyanov, Yu. N.

2012-07-01

124

Increasing the strength of nanocrystalline steels by annealing: Is segregation necessary?  

PubMed Central

Hardening phenomena in nanocrystalline metals after annealing have been widely reported, and the subject of much recent debate. Solute segregation to grain boundaries and dislocation source hardening have been proposed to cause the strengthening. To shed light on the dominant mechanisms, we present results from mechanical experiments and atom probe tomography on samples with similar grain size but different amounts of solute segregation and different boundary chemistries. PMID:25598694

Renk, O.; Hohenwarter, A.; Eder, K.; Kormout, K.S.; Cairney, J.M.; Pippan, R.

2015-01-01

125

Effect of the annealing temperature on dynamic and structural properties of Co2FeAl thin films  

NASA Astrophysics Data System (ADS)

10 nm and 50 nm thick Co2FeAl (CFA) thin films have been deposited on thermally oxidized Si(001) substrates by magnetron sputtering using a Tantalum cap layer and were then ex-situ annealed at 415°C, 515°C and 615°C during 15 minutes in vacuum. X-rays diffraction indicates that films CFA are polycrystalline and exhibit an in-plane isotropy growth. Ferromagnetic resonance measurements, using a microstrip line (MS-FMR), reveal a huge interfacial perpendicular magnetic anisotropy and small in-plane uniaxial anisotropy both annealing temperature-dependent. The MS-FMR data also allow concluding that the gyromagnetic factor remains constant and that the exchange stiffness constant increases with annealing temperature. Finally, the FMR linewidth decreases with increasing annealing temperature due to the enhancement of the chemical order, and allow deriving a very low intrinsic damping parameter (1.3×10-3 at 615°C).

Belmeguenai, M.; Tuzcuoglu, H.; Gabor, M.; Petrisor, T.; Tiusan, C.; Zighem, F.; Chérif, S. M.; Moch, P.

2014-07-01

126

Neutronic optimization in high conversion Th-{sup 233}U fuel assembly with simulated annealing  

SciTech Connect

This paper reports on fuel design optimization of a PWR operating in a self sustainable Th-{sup 233}U fuel cycle. Monte Carlo simulated annealing method was used in order to identify the fuel assembly configuration with the most attractive breeding performance. In previous studies, it was shown that breeding may be achieved by employing heterogeneous Seed-Blanket fuel geometry. The arrangement of seed and blanket pins within the assemblies may be determined by varying the designed parameters based on basic reactor physics phenomena which affect breeding. However, the amount of free parameters may still prove to be prohibitively large in order to systematically explore the design space for optimal solution. Therefore, the Monte Carlo annealing algorithm for neutronic optimization is applied in order to identify the most favorable design. The objective of simulated annealing optimization is to find a set of design parameters, which maximizes some given performance function (such as relative period of net breeding) under specified constraints (such as fuel cycle length). The first objective of the study was to demonstrate that the simulated annealing optimization algorithm will lead to the same fuel pins arrangement as was obtained in the previous studies which used only basic physics phenomena as guidance for optimization. In the second part of this work, the simulated annealing method was used to optimize fuel pins arrangement in much larger fuel assembly, where the basic physics intuition does not yield clearly optimal configuration. The simulated annealing method was found to be very efficient in selecting the optimal design in both cases. In the future, this method will be used for optimization of fuel assembly design with larger number of free parameters in order to determine the most favorable trade-off between the breeding performance and core average power density. (authors)

Kotlyar, D.; Shwageraus, E. [Dept. of Nuclear Engineering, Ben-Gurion Univ., POB 653, Beer Sheva 84105 (Israel)

2012-07-01

127

Semantic search via concept annealing  

NASA Astrophysics Data System (ADS)

Annealing, in metallurgy and materials science, is a heat treatment wherein the microstructure of a material is altered, causing changes in its properties such as strength and hardness. We define concept annealing as a lexical, syntactic, and semantic expansion capability (the removal of defects and the internal stresses that cause term- and phrase-based search failure) coupled with a directed contraction capability (semantically-related terms, queries, and concepts nucleate and grow to replace those originally deformed by internal stresses). These two capabilities are tied together in a control loop mediated by the information retrieval precision and recall metrics coupled with intuition provided by the operator. The specific representations developed have been targeted at facilitating highly efficient and effective semantic indexing and searching. This new generation of Find capability enables additional processing (i.e. all-source tracking, relationship extraction, and total system resource management) at rates, precisions, and accuracies previously considered infeasible. In a recent experiment, an order magnitude reduction in time to actionable intelligence and nearly three orderss magnitude reduction in false alarm rate was achieved.

Dunkelberger, Kirk A.

2007-04-01

128

Rapid Annealing Of Amorphous Hydrogenated Carbon  

NASA Technical Reports Server (NTRS)

Report describes experiments to determine effects of rapid annealing on films of amorphous hydrogenated carbon. Study represents first efforts to provide information for applications of a-C:H films where rapid thermal processing required. Major finding, annealing causes abrupt increase in absorption and concomitant decrease in optical band gap. Most of change occurs during first 20 s, continues during longer annealing times. Extend of change increases with annealing temperature. Researchers hypothesize abrupt initial change caused by loss of hydrogen, while gradual subsequent change due to polymerization of remaining carbon into crystallites or sheets of graphite. Optical band gaps of unannealed specimens on silicon substrates lower than those of specimens on quartz substrates.

Alterovitz, Samuel A.; Pouch, John J.; Warner, Joseph D.

1989-01-01

129

An ultrahigh vacuum compatible sample holder for studying complex metal surfaces  

Microsoft Academic Search

We present a design of a compact and versatile sample holder meant for studying complex (ternary) metallic crystals that require sputtering and annealing to high temperatures under ultrahigh vacuum (10-10 mbar range) for obtaining the clean, ordered and stoichiometric surface. A resistive heater is fixed to the sample holder and not to the sample plate, and thus can be thoroughly

A. K. Shukla; M. Maniraj; S. W. D'Souza; J. Nayak; S. R. Barman

2010-01-01

130

An ultrahigh vacuum compatible sample holder for studying complex metal surfaces  

Microsoft Academic Search

We present a design of a compact and versatile sample holder meant for studying complex (ternary) metallic crystals that require sputtering and annealing to high temperatures under ultrahigh vacuum (10?10 mbar range) for obtaining the clean, ordered and stoichiometric surface. A resistive heater is fixed to the sample holder and not to the sample plate, and thus can be thoroughly

A. K. Shukla; M. Maniraj; S. W. D’Souza; J. Nayak; S. R. Barman

2010-01-01

131

Teaching optical phenomena with Tracker  

NASA Astrophysics Data System (ADS)

Since the invention and dissemination of domestic laser pointers, observing optical phenomena is a relatively easy task. Any student can buy a laser and experience at home, in a qualitative way, the reflection, refraction and even diffraction phenomena of light. However, quantitative experiments need instruments of high precision that have a relatively complex setup. Fortunately, nowadays it is possible to analyse optical phenomena in a simple and quantitative way using the freeware video analysis software ‘Tracker’. In this paper, we show the advantages of video-based experimental activities for teaching concepts in optics. We intend to show: (a) how easy the study of such phenomena can be, even at home, because only simple materials are needed, and Tracker provides the necessary measuring instruments; and (b) how we can use Tracker to improve students’ understanding of some optical concepts. We give examples using video modelling to study the laws of reflection, Snell’s laws, focal distances in lenses and mirrors, and diffraction phenomena, which we hope will motivate teachers to implement it in their own classes and schools.

Rodrigues, M.; Simeão Carvalho, P.

2014-11-01

132

ISABELLE vacuum systems  

SciTech Connect

The Intersecting Storage Accelerator (ISABELLE) consists of two rings having a circumference of 3.8 km each. In these rings superconducting magnets, held at 4 K, bend and focus the proton beam which is accelerated up to 400 GeV. Due to very different pressure requirements, ISABELLE has two completely independent vacuum systems. One, which operates at 1 x 10/sup -11/ Torr, provides a very clean environment for the circulating proton beam. Here only ion and titanium sublimation pumps are used to provide the vacuum. The other system maintains superconducting magnet vessels at a pressure below 1 x 10/sup -4/ Torr, since at this pressure the gas conduction becomes negligible. In this so-called insulating vacuum system, turbomolecular pumps pump the inadvertent small helium leaks. Other gases are cryocondensed on the cold surfaces of the cryogenic system. The basic element of ISABELLE known as Full Cell containing 45 meters of beam tube, 8 pumping stations, 8 superconducting magnets and complete instrumentation has been constructed, leak checked and tested. All design parameters have been achieved in both vacuum systems. The two vacuum systems are described with particular emphasis on the influence of superconducting magnets in the selection of materials and UHV components.

Halama, H J

1980-01-01

133

The microstructural response of mill-annealed and solution-annealed INCONEL 600 to heat treatment  

Microsoft Academic Search

Samples of INCONEL* 600 were examined in the mill-annealed and solution-annealed states, and after isothermal annealing at 400 °C and 650 °C. The corrosion behavior of the samples was examined, analytical electron microscopy was used to determine the microstructures present and the chemistry of grain boundaries, and Auger electron spectroscopy was used to measure grain boundary segregation. Samples of different

Ernest L. Hall; Clyde L. Briant

1985-01-01

134

The effect of annealing on the spin-transfer torques of MgO MTJ nanopillars  

NASA Astrophysics Data System (ADS)

Thermal annealing is essential for enhancing the tunneling magnetoresistane (TMR) of magnetic tunnel junctions, and many studies have focused on the effect of annealing on MTJ chemical, structural, and electrical transport properties. Here, we report the magnetic, electronic properties and the in-plane and field-like spin-transfer torques (STT) in both as-grown and post-annealed FeCoB/MgO/FeCoB MTJs nanopillars. We find that the 350 C vacuum annealing breaks the symmetry of the bias dependence of the TMR, conductivity, and switching phase diagram (SPD). Moreover STT-FMR measurements indicate that annealing substantially increases the in-plane torque asymmetry with bias voltage direction, as well as affecting the field-like torque magnitude, with the latter indicating a very significant enhancement of interlayer exchange coupling across the barrier. This STT change is consistent with the change in chemical composition and structural coherency of the MTJ interfaces and electrodes, indicated by XRD and analytical STEM analyzes.

Li, Yun; Tseng, Hsin-Wei; Huang, Pinshane; Read, John; Ralph, Dan; Buhrman, Robert

2011-03-01

135

Effect of annealing process on TiN/TiC bilayers grown by pulsed arc discharge  

NASA Astrophysics Data System (ADS)

In this work, a study of annealing process effect on TiN/TiC bilayer is presented. The annealing temperature was varied between room temperature and 500 °C. Materials were produced by the plasma-assisted pulsed vacuum arc discharge technique. In order to grow the films, a target of Ti with 99.9999% purity and stainless-steel 304 substrate were used. For the production of TiN layer, the reaction chamber was filled up with nitrogen gas until reaching 25 Pa and the discharge was performed at 310 V. The TiC layer was grown in a methane atmosphere at 30 Pa and 270 V. X-ray diffraction and X photoelectron spectroscopy were employed for studying the structure and chemical composition evolution during the annealing process. At 400 °C, TiO2 phase begun to appear and it was well observed at 500 °C. Crystallite size and microstrain was obtained as a function of the annealing temperature. XPS technique was employed for analyzing the bilayers before and after the annealing process. Narrow spectra of Ti2p, N1s and O1s were obtained, presenting TiO phases.

Ramos-Rivera, L.; Escobar, D.; Benavides-Palacios, V.; Arango, P. J.; Restrepo-Parra, E.

2012-08-01

136

MgB 2 superconducting thin films sequentially fabricated using DC magnetron sputtering and thermionic vacuum arc method  

NASA Astrophysics Data System (ADS)

In this work, we discuss fabrication and characterization of MgB 2 thin films obtained by sequential deposition and annealing of sandwich like Mg/B/Mg thin films on glass substrates. Mg and B films were prepared using DC magnetron sputtering and thermionic vacuum arc techniques, respectively. The MgB 2 thin films showed superconducting critical transition at 33 K after annealing at 650 °C.

Okur, S.; Kalkanci, M.; Pat, S.; Ekem, N.; Akan, T.; Balbag, Z.; Musa, G.; Tanoglu, M.

2007-11-01

137

Investigations on the structure, composition and performance of nanocrystalline thin film thermocouples deposited using anodic vacuum arc  

Microsoft Academic Search

This paper deals with the performance study of nanocrystalline thin film thermocouples (TFTCs) fabricated using anodic vacuum arc plasma aided deposition technique. Various single junction single elemental metal–metal pairs, elemental metal–metal alloy pairs, and metal alloy–metal alloy pairs were developed on glass substrates Elemental metal films were annealed at 10?4Pa for 4h while metal alloy films were annealed for 5h.

S. K. Mukherjee; M. K. Sinha; B. Pathak; S. K. Rout; P. K. Barhai; A. K. Balamurugan; A. K. Tyagi; F. L. Ng

2010-01-01

138

Scaling law in thermal phenomena  

E-print Network

In this paper the scaling law for the relaxation times in thermal phenomena is investigated. It is shown that dependent on the value of the parameter K=E/m(c\\alpha)^2,where E is the energy which is delivered to the system, m is the parton mass and \\alpha=1/137 for electromagnetic interaction and \\alpha=0.16 for strong interaction respectively, heat transport is diffusive, for K1. For the system with N partons the relaxation time is scaled as \\tau^N\\to N (\\hbar/(mc\\alpha)^2). Key words: Thermal phenomena, scaling

M. Kozlowski; J. Marciak-Kozlowska

2006-10-29

139

Abnormal pressures as hydrodynamic phenomena  

USGS Publications Warehouse

So-called abnormal pressures, subsurface fluid pressures significantly higher or lower than hydrostatic, have excited speculation about their origin since subsurface exploration first encountered them. Two distinct conceptual models for abnormal pressures have gained currency among earth scientists. The static model sees abnormal pressures generally as relict features preserved by a virtual absence of fluid flow over geologic time. The hydrodynamic model instead envisions abnormal pressures as phenomena in which flow usually plays an important role. This paper develops the theoretical framework for abnormal pressures as hydrodynamic phenomena, shows that it explains the manifold occurrences of abnormal pressures, and examines the implications of this approach. -from Author

Neuzil, C.E.

1995-01-01

140

Effects of thermal annealing on the evolution of He bubbles in zirconia  

NASA Astrophysics Data System (ADS)

Single crystals of yttria-stabilized zirconia were implanted with 100 keV He ions at two fluences of 9 × 1016 and 3 × 1017 cm-2 (5 and 17 He at.%). In order to investigate the effect of thermal annealing on the evolution of both zirconia lattice and implanted He, the samples were annealed at several temperatures ranging from 500 °C to 1400 °C. Three complementary analysis techniques, RBS/C, AFM and TEM were used to study structural damage and surface morphology of the crystal before and after implantation. Results show different He evolution phenomena under the two implantation fluences. It is inferred that, at the lower fluence, the migration and agglomeration of He ions lead to bubble formation after annealing. These bubbles jack up sample surface causing the deformation of surface region and the damage level of surface region increase accordingly. As the temperature continues to increase, He gradually releases and the damage recovers. However, at the higher fluence, the He concentration is sufficient to induce bubble precipitation without annealing. He release and damage recovering is less efficient upon annealing.

Kong, Shuyan; Velisa, Gihan; Debelle, Aurélien; Yang, Tengfei; Wang, Chenxu; Thomé, Lionel; Xue, Jianming; Yan, Sha; Wang, Yugang

2014-05-01

141

Vacuum driven accelerated expansion  

E-print Network

It has been shown that an improved estimation of quantum vacuum energy can yield not only acceptable but also experimentally sensible results. The very idea consists in a straightforward extraction of gravitationally interacting part of the full quantum vacuum energy by means of gauge transformations. The implementation of the idea has been performed in the formalism of effective action, in the language of Schwinger's proper time and the Seeley-DeWitt heat kernel expansion, in the background of the Friedmann-Robertson-Walker geometry.

Bogus?aw Broda; Piotr Bronowski; Marcin Ostrowski; Micha? Szanecki

2008-12-29

142

"Un-annealed and Annealed Pd Ultra-Thin Film on SiC Characterized by Scanning Probe Microscopy and X-ray Photoelectron Spectroscopy"  

NASA Technical Reports Server (NTRS)

Pd/SiC has been used as a hydrogen and a hydrocarbon gas sensor operated at high temperature. UHV (Ultra High Vacuum)-Scanning Tunneling Microscopy (STM), Atomic Force Microscopy (AFM) and X-ray Photoelectron Spectroscopy (XPS) techniques were applied to study the relationship between the morphology and chemical compositions for Pd ultra-thin films on SiC (less than 30 angstroms) at different annealing temperatures. Pd ultra-thin film on 6H-SiC was prepared by the RF sputtering method. The morphology from UHV-STM and AFM shows that the Pd thin film was well deposited on SiC substrate, and the Pd was partially aggregated to round shaped participates at an annealing temperature of 300 C. At 400 C, the amount of surface participates decreases, and some strap shape participates appear. From XPS, Pd2Si was formed on the surface after annealing at 300 C, and all Pd reacted with SiC to form Pd2Si after annealing at 400 C. The intensity of the XPS Pd peak decreases enormously at 400 C. The Pd film diffused into SiC, and the Schottky barrier height has almost no changes. The work shows the Pd sicilides/SiC have the same electronic properties with Pd/SiC, and explains why the Pd/SiC sensor still responds to hydrogen at high operating temperatures.

Lu, W. J.; Shi, D. T.; Elshot, K.; Bryant, E.; Lafate, K.; Chen, H.; Burger, A.; Collins, W. E.

1998-01-01

143

Quantum Phenomena Observed Using Electrons  

SciTech Connect

Electron phase microscopy based on the Aharonov-Bohm (AB) effect principle has been used to illuminate fundamental phenomena concerning magnetism and superconductivity by visualizing quantitative magnetic lines of force. This paper deals with confirmation experiments on the AB effect, the magnetization process of tiny magnetic heads for perpendicular recording, and vortex behaviors in high-Tc superconductors.

Tonomura, Akira [Okinawa Institute of Science and Technology, Onna-son, Okinawa 904-0412 (Japan); Advanced Research Laboratory, Hitachi, Ltd., Hatoyama, Saitama, 350-0395 (Japan); Advanced Science Institute, RIKEN, Wako, Saitama, 351-0198 (Japan)

2011-05-06

144

Virtual Physics Laboratory: Wave Phenomena  

NSDL National Science Digital Library

This site from Northwestern University discusses wave phenomena. The site features interactive applets of various wave types, including longitudinal, transverse, mixed, and sound waves. Also included are animations of superposition, beat frequencies, and the distinction between phase and group velocities, wave packets, and wave reflections.

Astronomy, The D.; University, Northwestern

145

Graphene tests of Klein phenomena  

E-print Network

Graphene is characterized by chiral electronic excitations. As such it provides a perfect testing ground for the production of Klein pairs (electron/holes). If confirmed, the standard results for barrier phenomena must be reconsidered with, as a byproduct, the accumulation within the barrier of holes.

Stefano De Leo; Pietro Rotelli

2012-02-07

146

Visualizing Chemical Phenomena in Microdroplets  

ERIC Educational Resources Information Center

Phenomena that occur in microdroplets are described to the undergraduate chemistry community. Droplets having a diameter in the micrometer range can have unique and interesting properties, which arise because of their small size and, especially, their high surface area-to-volume ratio. Students are generally unfamiliar with the characteristics of…

Lee, Sunghee; Wiener, Joseph

2011-01-01

147

Gravitational Anomaly and Transport Phenomena  

Microsoft Academic Search

Quantum anomalies give rise to new transport phenomena. In particular, a magnetic field can induce an anomalous current via the chiral magnetic effect and a vortex in the relativistic fluid can also induce a current via the chiral vortical effect. The related transport coefficients can be calculated via Kubo formulas. We evaluate the Kubo formula for the anomalous vortical conductivity

Karl Landsteiner; Eugenio Megías; Francisco Pena-Benitez

2011-01-01

148

URANIUM PYROPHORICITY PHENOMENA AND PREDICTION  

Microsoft Academic Search

We have compiled a topical reference on the phenomena, experiences, experiments, and prediction of uranium pyrophoricity for the Hanford Spent Nuclear Fuel Project (SNFP) with specific applications to SNFP process and situations. The purpose of the compilation is to create a reference to integrate and preserve this knowledge. Decades ago, uranium and zirconium fires were commonplace at Atomic Energy Commission

Martin G. Plys; Michael Epstein; Boro Malinovic

149

Critical phenomena in atmospheric precipitation  

E-print Network

LETTERS Critical phenomena in atmospheric precipitation OLE PETERS1,2,3 * AND J. DAVID NEELIN3 1 convection and precipitation (the order parameter)--with correlated regions on scales of tens to hundreds the climatological mean by an order of magnitude or more. Moist convection and the accompanying precipitation have

Loss, Daniel

150

Magnetostrictive Phenomena in Magnetorheological Elastomers  

Microsoft Academic Search

A host of fascinating and useful magnetic phenomena are found in composites containing magnetizable particles in viscoelastic solids. Embedding magnetically soft iron particles in natural rubber produces a class of magnetostrictive composites sometimes termed magnetorheological (MR) elastomers. We have previously shown that these materials can exhibit viscoelastic moduli that increase substantially in an applied magnetic field. In this paper, we

J. M. Ginder; S. M. Clark; W. F. Schlotter; M. E. Nichols

2002-01-01

151

Tuning of deep level emission in highly oriented electrodeposited ZnO nanorods by post growth annealing treatments  

NASA Astrophysics Data System (ADS)

Highly dense and c-axis oriented zinc oxide (ZnO) nanorods with hexagonal wurtzite facets were deposited on fluorine doped tin oxide coated glass substrates by a simple and cost-effective electrodeposition method at low bath temperature (80 °C). The as-grown samples were then annealed at various temperatures (TA = 100-500 °C) in different environments (e.g., zinc, oxygen, air, and vacuum) to understand their photoluminescence (PL) behavior in the ultra-violet (UV) and the visible regions. The PL results revealed that the as-deposited ZnO nanorods consisted of oxygen vacancy (VO), zinc interstitial (Zni), and oxygen interstitial (Oi) defects and these can be reduced significantly by annealing in different environments at optimal annealing temperatures. However, the intensity of deep level emission increased for TA greater than the optimized values for the respective environments due to the introduction of various defect centers. For example, for TA ? 450 °C in the oxygen and air environments, the density of Oi defects increased, whereas, the green emission associated with VO is dominant in the vacuum annealed (TA = 500 °C) ZnO nanorods. The UV peak red shifted after the post-growth annealing treatments in all the environments and the vacuum annealed sample exhibited highest UV peak intensity. The observations from the PL data are supported by the micro-Raman spectroscopy. The present study gives new insight into the origin of different defects that exist in the electrodeposited ZnO nanorods and how these defects can be precisely controlled in order to get the desired emissions for the opto-electronic applications.

Simimol, A.; Manikandanath, N. T.; Anappara, Aji A.; Chowdhury, Prasanta; Barshilia, Harish C.

2014-08-01

152

A vacuum chamber feedthrough  

NASA Technical Reports Server (NTRS)

Simple and inexpensive microwave feedthrough has been designed which transfers 130 ns, 5kV pulse into vacuum chamber. Feedthrough may be used over wide range and is adaptable to most coaxial cables, since either multistrand or single strand center conductor cable can be used.

Brown, V. D.

1973-01-01

153

Vacuum ultraviolet holography  

NASA Technical Reports Server (NTRS)

The authors report the first demonstration of holographic techniques in the vacuum ultraviolet spectral region. Holograms were produced with coherent 1182 A radiation. The holograms were recorded in polymethyl methacrylate and read out with an electron microscope. A holographic grating with a fringe spacing of 836 A was produced and far-field Fraunhofer holograms of sub-micron particles were recorded.

Bjorklund, G. C.; Harris, S. E.; Young, J. F.

1974-01-01

154

Vacuum ultraviolet holography  

NASA Technical Reports Server (NTRS)

We report the first demonstration of holographic techniques in the vacuum ultraviolet spectral region. Holograms were produced with coherent 1182-A radiation. The holograms were recorded in polymethyl methacrylate and examined with an electron microscope. A holographic grating with a fringe spacing of 386 A was produced and far-field Fraunhofer holograms of submicron particles were recorded.

Bjorklund, G. C.; Harris, S. E.; Young, J. F.

1974-01-01

155

Vacuum insulator coating development  

Microsoft Academic Search

The authors discuss the electrical and mechanical requirements for vacuum insulators in high peak power generators. To increase the lifetime of these insulators, they have developed a coating called Dendresist. This coating has extended the insulator lifetime on the PITHON, DM2, CASINO, and Double-EAGLE pulsed power generators. They describe its development, and compare its electrical and mechanical strength to that

I. S. Roth; P. S. Sincerny; L. Mandelcorn; M. Mendelsohn; D. Smith; T. G. Engel; L. Schlitt; C. M. Cooke

1997-01-01

156

On Lovelock vacuum solution  

E-print Network

We show that the asymptotic large $r$ limit of all Lovelock vacuum and electrovac solutions with $\\Lambda$ is always the Einstein solution in $d \\geq 2n+1$ dimensions. It is completely free of the order $n$ of the Lovelock polynomial indicating universal asymptotic behaviour.

Naresh Dadhich

2010-12-18

157

Analytical Study of Thermal Annealing Behaviour of Erbium Emission in Er2O3-Sol-Gel Silica Films  

E-print Network

Room-temperature 1535-nm-band photoluminescence in ~126 nm silica films (6 at. % doping), produced by spin-coating an Er2O3 and tetraethylorthosilicate sol-gel formulation on silicon substrates, was studied as a function of vacuum furnace annealing (500 to 1050 degrees C). Emission is strongly enhanced for annealing near 850 degrees C, which is shown by modeling the temperature dependence as arising from thermally-activated removal of hydroxyl ions. Suitability of such a process for silicon-based applications is discussed.

Abedrabbo, Sufian; Fiory, Anthony; 10.1088/0022-3727/44/31/315401

2012-01-01

158

A radiation hard vacuum switch  

DOEpatents

A vacuum switch with an isolated trigger probe which is not directly connected to the switching electrodes. The vacuum switch within the plasmatron is triggered by plasma expansion initiated by the trigger probe which travels through an opening to reach the vacuum switch elements. The plasma arc created is directed by the opening to the space between the anode and cathode of the vacuum switch to cause conduction. 3 figs.

Boettcher, G.E.

1988-07-19

159

Transport phenomena in nanoporous materials.  

PubMed

Diffusion, that is, the irregular movement of atoms and molecules, is a universal phenomenon of mass transfer occurring in all states of matter. It is of equal importance for fundamental research and technological applications. The present review deals with the challenges of the reliable observation of these phenomena in nanoporous materials. Starting with a survey of the different variants of diffusion measurement, it highlights the potentials of "microscopic" techniques, notably the pulsed field gradient (PFG) technique of NMR and the techniques of microimaging by interference microscopy (IFM) and IR microscopy (IRM). Considering ensembles of guest molecules, these techniques are able to directly record mass transfer phenomena over distances of typically micrometers. Their concerted application has given rise to the clarification of long-standing discrepancies, notably between microscopic equilibrium and macroscopic non-equilibrium measurements, and to a wealth of new information about molecular transport under confinement, hitherto often inaccessible and sometimes even unimaginable. PMID:25123096

Kärger, Jörg

2015-01-12

160

Surge-damping vacuum valve  

DOEpatents

A valve having a mechanism for damping out flow surges in a vacuum system which utilizes a slotted spring-loaded disk positioned adjacent the valve's vacuum port. Under flow surge conditions, the differential pressure forces the disk into sealing engagement with the vacuum port, thereby restricting the flow path to the slots in the disk damping out the flow surge.

Bullock, Jack C. (Pleasanton, CA); Kelly, Benjamin E. (Tracy, CA)

1980-01-01

161

Portable vacuum object handling device  

SciTech Connect

The disclosure relates to a portable device adapted to handle objects which are not to be touched by hand. A piston and bore wall form a vacuum chamber communicating with an adaptor sealably engageable with an object to be lifted. The piston is manually moved and set to establish vacuum. A valve is manually actuable to apply the vacuum to lift the object.

Anderson, G.H.

1981-07-30

162

Portable vacuum object handling device  

DOEpatents

The disclosure relates to a portable device adapted to handle objects which are not to be touched by hand. A piston and bore wall form a vacuum chamber communicating with an adaptor sealably engageable with an object to be lifted. The piston is manually moved and set to establish vacuum. A valve is manually actuatable to apply the vacuum to lift the object.

Anderson, Gordon H. (Los Alamos, NM)

1983-08-09

163

New phenomena searches at CDF  

SciTech Connect

The authors report on recent results from the Collider Detector at Fermilab (CDF) experiment, which is accumulating data from proton-antiproton collisions with {radical}s = 1.96 TeV at Run II of the Fermilab Tevatron. The new phenomena being explored include Higgs, Supersymmetry, and large extra dimensions. They also present the latest results of searches for heavy objects, which would indicate physics beyond the Standard Model.

Soha, Aron; /UC, Davis

2006-04-01

164

Mathematical Modeling of Diverse Phenomena  

NASA Technical Reports Server (NTRS)

Tensor calculus is applied to the formulation of mathematical models of diverse phenomena. Aeronautics, fluid dynamics, and cosmology are among the areas of application. The feasibility of combining tensor methods and computer capability to formulate problems is demonstrated. The techniques described are an attempt to simplify the formulation of mathematical models by reducing the modeling process to a series of routine operations, which can be performed either manually or by computer.

Howard, J. C.

1979-01-01

165

Compact vacuum insulation  

DOEpatents

An ultra-thin compact vacuum insulation panel is comprised of two hard, but bendable metal wall sheets closely spaced apart from each other and welded around the edges to enclose a vacuum chamber. Glass or ceramic spacers hold the wall sheets apart. The spacers can be discrete spherical beads or monolithic sheets of glass or ceramic webs with nodules protruding therefrom to form essentially "point" or "line" contacts with the metal wall sheets. In the case of monolithic spacers that form "line" contacts, two such spacers with the line contacts running perpendicular to each other form effectively "point" contacts at the intersections. Corrugations accommodate bending and expansion, tubular insulated pipes and conduits, and preferred applications are also included.

Benson, David K. (Golden, CO); Potter, Thomas F. (Denver, CO)

1993-01-01

166

Compact vacuum insulation embodiments  

DOEpatents

An ultra-thin compact vacuum insulation panel is comprised of two hard, but bendable metal wall sheets closely spaced apart from each other and welded around the edges to enclose a vacuum chamber. Glass or ceramic spacers hold the wall sheets apart. The spacers can be discrete spherical beads or monolithic sheets of glass or ceramic webs with nodules protruding therefrom to form essentially "point" or "line" contacts with the metal wall sheets. In the case of monolithic spacers that form "line" contacts, two such spacers with the line contacts running perpendicular to each other form effectively "point" contacts at the intersections. Corrugations accommodate bending and expansion, tubular insulated pipes and conduits, and preferred applications are also included.

Benson, David K. (Golden, CO); Potter, Thomas F. (Denver, CO)

1992-01-01

167

Compact vacuum insulation  

DOEpatents

An ultra-thin compact vacuum insulation panel is comprised of two hard, but bendable metal wall sheets closely spaced apart from each other and welded around the edges to enclose a vacuum chamber. Glass or ceramic spacers hold the wall sheets apart. The spacers can be discrete spherical beads or monolithic sheets of glass or ceramic webs with nodules protruding therefrom to form essentially point'' or line'' contacts with the metal wall sheets. In the case of monolithic spacers that form line'' contacts, two such spacers with the line contacts running perpendicular to each other form effectively point'' contacts at the intersections. Corrugations accommodate bending and expansion, tubular insulated pipes and conduits, and preferred applications are also included.

Benson, D.K.; Potter, T.F.

1993-01-05

168

Integrated structure vacuum tube  

NASA Technical Reports Server (NTRS)

High efficiency, multi-dimensional thin film vacuum tubes suitable for use in high temperature, high radiation environments are described. The tubes are fabricated by placing thin film electrode members in selected arrays on facing interior wall surfaces of an alumina substrate envelope. Cathode members are formed using thin films of triple carbonate. The photoresist used in photolithography aids in activation of the cathodes by carbonizing and reacting with the reduced carbonates when heated in vacuum during forming. The finely powdered triple carbonate is mixed with the photoresist used to delineate the cathode locations in the conventional solid state photolithographic manner. Anode and grid members are formed using thin films of refractory metal. Electron flow in the tubes is between grid elements from cathode to anode as in a conventional three-dimensional tube.

Dimeff, J.; Kerwin, W. J. (inventors)

1976-01-01

169

Vacuum tool manipulator  

DOEpatents

Apparatus for manipulating a vacuum hose in a reactor vessel comprises a housing with two opposing openings, an arm carried by the housing and deployable from a stowed position essentially completely within the housing to an extended position where the arm extends through the two openings in a generally horizontal position. The arm preferably has a two-fingered gripping device for gripping the vacuum hose but may carry a different end effector such as a grinding wheel. The fingers are opened and closed by one air cylinder. A second air cylinder extends the device. A third air cylinder within the housing pivotally pulls the opposing end of the arm into the housing via a pivoting member pivotally connected between the third air cylinder shaft and the arm.

Zollinger, William T. (3927 Almon Dr., Martinez, GA 30907)

1993-01-01

170

Vacuum tool manipulator  

DOEpatents

Apparatus for manipulating a vacuum hose in a reactor vessel comprises a housing with two opposing openings, an arm carried by the housing and deployable from a stowed position essentially completely within the housing to an extended position where the arm extends through the two openings in a generally horizontal position. The arm preferably has a two-fingered gripping device for gripping the vacuum hose but may carry a different end effector such as a grinding wheel. The fingers are opened and closed by one air cylinder. A second air cylinder extends the device. A third air cylinder within the housing pivotally pulls the opposing end of the arm into the housing via a pivoting member pivotally connected between the third air cylinder shaft and the arm. 6 figures.

Zollinger, W.T.

1993-11-23

171

The vacuum energy crisis  

E-print Network

The smallness of the vacuum energy density and its near coincidence with the average matter density of the universe are naturally explained by anthropic selection. An alternative explanation, based on the cyclic model of Steinhardt and Turok, does not address the coincidence problem and is therefore less convincing. This article appeared in ``Science'' (4 May 2006) as a ``perspective'' for Steinhardt and Turok's paper in the same issue (astro-ph/0605173).

Alexander Vilenkin

2006-05-09

172

Is vacuum dispersive?  

E-print Network

The question we ask is: does the speed of light {\\it{in vacuo}} depend on its frequency? While the answer is NO in the frame of classical physics, we point out that the opposite could be true if one takes into account the polarization of Dirac sea. We estimate the dependence of the index of refraction of vacuum + Dirac sea versus the wavelength of an incoming beam, and suggest a way to test this effect.

Yves Pomeau

2014-09-02

173

The LHC Vacuum System  

NASA Astrophysics Data System (ADS)

The Large Hadron Collider (LHC) at CERN, involves two proton storage rings with colliding beams of 7 TeV. The machine will be housed in the existing LEP tunnel and requires 16 m long superconducting bending magnets. The vacuum chamber will be the inner wall of the cryostat and hence at the temperature of the magnet cold bore, i.e. at 1.9 K and therefore a very good cryo-pump. To reduce the cryogenic power consumption, the heat load from synchrotron radiation and from the image currents in the vacuum chamber will be absorbed on a 'beam screen', which operates between 5 and 20 K, inserted in the magnet cold bore. The design pressure necessary for operation must provide a lifetime of many days and a stringent requirement comes from the power deposition in the superconducting magnet coils due to protons scattered on the residual gas which could lead to a magnet quench. Cryo-pumping of gas on the cold surfaces provides the necessary low gas densities but it must be ensured that the vapour pressure of cryo-sorbed molecules, of which H2 and He would be the most critical species, remains within acceptable limits. The room temperature sections of the LHC, specifically in the experiments, the vacuum must be stable against ion induced desorption and ISR-type 'pressure bumps'.

Gröbner, O.

1997-05-01

174

Characterization of e-beam evaporated hafnium oxide thin films on post thermal annealing  

NASA Astrophysics Data System (ADS)

HfO2 thin films (80 nm thick) were fabricated using electron beam evaporation technique at various substrate temperatures ranging from 25 ° to 120 °C. These films were then thermally annealed at 500 °C for one and half hour in vacuum. After thermal annealing, films were characterized through XRD, AFM and Spectrophotometry. In this regard, it was observed that the as-deposited HfO2 films were mostly amorphous in nature and transformed to polycrystalline with monoclinic structure after annealing at 500 °C. Moreover, films fabricated at different substrate temperatures revealed different morphologies and crystallite orientations on thermal annealing. Such different morphologies and crystallite orientations appear to be responsible for any variations in the surface roughness and the optical properties e.g. optical band gap energy (3.4-3.65 eV), refractive index (1.25-2.55), extinction coefficient (0.25-0.46) etc. These optical properties demonstrate oscillatory behavior with different substrate temperatures due to crystallite growth along different preferred orientations. On the basis of above mentioned facts, it can be concluded that the post thermal annealing demonstrates better tendency to change the structural and optical properties of HfO2 thin films. In addition, annealed HfO2 films showed better reflectivity (5-10%) in the NIR region which can further be improved by inserting a metallic layer into the oxide-metal-oxide (O-M-O) structure. Hence, such O-M-O structures can be useful for heat mirror applications.

Ramzan, M.; Wasiq, M. F.; Rana, A. M.; Ali, S.; Nadeem, M. Y.

2013-10-01

175

Annealing behavior of high permeability amorphous alloys  

SciTech Connect

Effects of low temperature annealing on the magnetic properties of the amorphous alloy Co/sub 71/ /sub 4/Fe/sub 4/ /sub 6/Si/sub 9/ /sub 6/B/sub 14/ /sub 4/ were investigated. Annealing this alloy below 400/sup 0/C results in magnetic hardening; annealing above 400/sup 0/C but below the crystallization temperature results in magnetic softening. Above the crystallization temperature the alloy hardens drastically and irreversibly. Conventional and high resolution transmission electron microscopy were used to show that the magnetic property changes at low temperatures occur while the alloy is truly amorphous. By imaging the magnetic microstructures, Lorentz electron microscopy has been able to detect the presence of microscopic inhomogeneities in this alloy. The low temperature annealing behavior of this alloy has been explained in terms of atomic pair ordering in the presence of the internal molecular field. Lorentz electron microscopy has been used to confirm this explanation.

Rabenberg, L.

1980-06-01

176

Enthalpy relaxation and annealing effect in polystyrene  

NASA Astrophysics Data System (ADS)

The effects of thermal history on the enthalpy relaxation in polystyrene are studied by differential scanning calorimetry. The temperature dependence of the specific heat in the liquid and the glassy states, that of relaxation time, and the exponent of the Kohlrausch-Williams-Watts function are determined by measurements of the thermal response against sinusoidal temperature variation. A phenomenological model equation previously proposed to interpret the memory effect in the frozen state is applied to the enthalpy relaxation and the evolution of entropy under a given thermal history is calculated. The annealing below the glass transition temperature produces two effects on enthalpy relaxation: the decay of excess entropy with annealing time in the early stage of annealing and the increase in relaxation time due to physical aging in the later stage. The crossover of these effects is reflected in the variation of temperature of the maximum specific heat observed in the heating process after annealing and cooling.

Sakatsuji, Waki; Konishi, Takashi; Miyamoto, Yoshihisa

2013-07-01

177

Solvothermal annealing of block copolymer thin films.  

PubMed

A two-stage annealing process for block copolymer films was introduced consisting of a solvent vapor exposure followed by a thermal cycle. By heating the film but not the chamber, changes in the ambient vapor pressure of the solvent were avoided. Films of block copolymers and homopolymers showed transient nonmonotonic swelling behavior immediately after solvent exposure that was dependent on how the thin film was cast before the anneal. Thermal cycling of the solvent-swelled block copolymer films during the solvent vapor anneal (SVA) caused the films to deswell in 1-10 s and produced well-ordered microdomains in templated 45.5 and 51.5 kg/mol polystyrene-block-polydimethylsiloxane films annealed in toluene and n-heptane vapors for total process times of 30 s to 5 min. PMID:24083573

Gotrik, Kevin W; Ross, C A

2013-11-13

178

Disorder in Quantum Vacuum: Casimir-Induced Localization of Matter Waves  

SciTech Connect

Disordered geometrical boundaries such as rough surfaces induce important modifications to the mode spectrum of the electromagnetic quantum vacuum. In analogy to Anderson localization of waves induced by a random potential, here we show that the Casimir-Polder interaction between a cold atomic sample and a rough surface also produces localization phenomena. These effects, that represent a macroscopic manifestation of disorder in quantum vacuum, should be observable with Bose-Einstein condensates expanding in proximity of rough surfaces.

Moreno, G. A. [IFIBA-Departamento de Fisica, FCEyN, UBA, Ciudad Universitaria, 1428 Buenos Aires (Argentina); Theoretical Division, MS B213, Los Alamos National Laboratory, Los Alamos, New Mexico 87545 (United States); Messina, R. [Laboratoire Kastler Brossel, case 74, CNRS, ENS, UPMC, Campus Jussieu, F-75252 Paris Cedex 05 (France); SYRTE--Observatoire de Paris 61, avenue de l'Observatoire, F-75014 Paris (France); Dalvit, D. A. R. [Theoretical Division, MS B213, Los Alamos National Laboratory, Los Alamos, New Mexico 87545 (United States); Lambrecht, A.; Reynaud, S. [Laboratoire Kastler Brossel, case 74, CNRS, ENS, UPMC, Campus Jussieu, F-75252 Paris Cedex 05 (France); Maia Neto, P. A. [Instituto de Fisica, UFRJ, CP 68528, Rio de Janeiro, RJ, 21941-972 (Brazil)

2010-11-19

179

Disorder in quantum vacuum: Casimir-induced localization of matter waves.  

PubMed

Disordered geometrical boundaries such as rough surfaces induce important modifications to the mode spectrum of the electromagnetic quantum vacuum. In analogy to Anderson localization of waves induced by a random potential, here we show that the Casimir-Polder interaction between a cold atomic sample and a rough surface also produces localization phenomena. These effects, that represent a macroscopic manifestation of disorder in quantum vacuum, should be observable with Bose-Einstein condensates expanding in proximity of rough surfaces. PMID:21231273

Moreno, G A; Messina, R; Dalvit, D A R; Lambrecht, A; Maia Neto, P A; Reynaud, S

2010-11-19

180

The microstructural response of mill-annealed and solution-annealed INCONEL 600 to heat treatment  

Microsoft Academic Search

Samples of INCONEL* 600 were examined in the mill-annealed and solution-annealed states, and after isothermal annealing at\\u000a 400 °C and 650 °C. The corrosion behavior of the samples was examined, analytical electron microscopy was used to determine\\u000a the microstructures present and the chemistry of grain boundaries, and Auger electron spectroscopy was used to measure grain\\u000a boundary segregation. Samples of different

Ernest L. Hall; Clyde L. Briant

1985-01-01

181

A study of magnetically annealed ferromagnetic materials  

E-print Network

mils in thickness were annealed in hydrogen at I, 000 C and cooled to room temperature. Then the specimens were reheated to above the Curie point and cooled slowly in the presence of a field applied in the same direction in the specimen as the field... A STUDY OF MAGNETICALLY ANNEALED FERROMAGNETIC MATERIALS A Thesis By DOMINGO RAMOS Submitted to the Graduate School of the Agricultural and Mechanical College of Texas in partial fulfillment of the requirements for the degree of MASTER...

Ramos, Domingo

2012-06-07

182

Gradient Solvent Vapor Annealing of Thin Films  

Microsoft Academic Search

The development of block copolymer materials for emerging nanotechnologies requires an understanding of how surface energy\\/chemistry and annealing conditions affect thin film self-assembly. Specifically, in solvent vapor annealing (SVA), the use of solvent mixtures and the manipulation of solvent vapor concentration are promising approaches for obtaining a desired morphology or nanostructure orientation. We designed and fabricated solvent-resistant devices to produce

Julie Albert; Timothy Bogart; Ronald Lewis; Thomas Epps

2011-01-01

183

Magnetic induced heating for ferritic metal annealing  

SciTech Connect

A method is described for annealing the wall of a nuclear reactor vessel, including, positioning an electromagnet within a vertically positioned nuclear reactor vessel by lowering the electromagnet into the vessel, supplying power to the electromagnet to generate substantially uniform heat in the vessel wall, maintaining the power to the electromagnet for a predetermined length of time which will anneal the vessel wall, and removing the electromagnet.

De Witt, G.L.; Huber, D.J.

1987-03-24

184

Polycrystalline silicon resistor trimming by laser annealing  

E-print Network

van der Pauw pattern and Kelvin resistors. Cross sectional view of test cell. SUPREM model of ion implantation and anneal steps. ESI Model 80 beam positioner, laser, snd optics path. . Change in resistance vs. laser power (A =1. 06@m). Change... and diffusion of carriers through the amorphous grain boundary instead of thermionic or field emission. This model predicts resistivity as a function of grain size, temperature, dopant concentration, snd applied voltage. 17 CHAPTER III LASER ANNEALING...

Crowley, Robert Terrence

2012-06-07

185

A ultra-high-vacuum wafer-fusion-bonding system.  

PubMed

The design of heterojunction devices is typically limited by material integration constraints and the energy band alignment. Wafer bonding can be used to integrate material pairs that cannot be epitaxially grown together due to large lattice mismatch. Control of the energy band alignment can be provided by formation of interface dipoles through control of the surface chemistry. We have developed an ultra-high-vacuum system for wafer-fusion-bonding semiconductors with in situ control and measurement of surface properties relevant to interface dipoles. A wafer-fusion-bonding chamber with annealing capabilities was integrated into an ultra-high-vacuum system with a sputtering chamber and an x-ray photoelectron spectroscopy system for preparing and measuring the surface chemistry of wafers prior to bonding. The design of the system along with initial results for the fusion-bonded InGaAs/Si heterojunction is presented. PMID:22667658

McKay, Kyle; Wolter, Scott; Kim, Jungsang

2012-05-01

186

A ultra-high-vacuum wafer-fusion-bonding system  

NASA Astrophysics Data System (ADS)

The design of heterojunction devices is typically limited by material integration constraints and the energy band alignment. Wafer bonding can be used to integrate material pairs that cannot be epitaxially grown together due to large lattice mismatch. Control of the energy band alignment can be provided by formation of interface dipoles through control of the surface chemistry. We have developed an ultra-high-vacuum system for wafer-fusion-bonding semiconductors with in situ control and measurement of surface properties relevant to interface dipoles. A wafer-fusion-bonding chamber with annealing capabilities was integrated into an ultra-high-vacuum system with a sputtering chamber and an x-ray photoelectron spectroscopy system for preparing and measuring the surface chemistry of wafers prior to bonding. The design of the system along with initial results for the fusion-bonded InGaAs/Si heterojunction is presented.

McKay, Kyle; Wolter, Scott; Kim, Jungsang

2012-05-01

187

Comparative study of the performance of quantum annealing and simulated annealing  

NASA Astrophysics Data System (ADS)

Relations of simulated annealing and quantum annealing are studied by a mapping from the transition matrix of classical Markovian dynamics of the Ising model to a quantum Hamiltonian and vice versa. It is shown that these two operators, the transition matrix and the Hamiltonian, share the eigenvalue spectrum. Thus, if simulated annealing with slow temperature change does not encounter a difficulty caused by an exponentially long relaxation time at a first-order phase transition, the same is true for the corresponding process of quantum annealing in the adiabatic limit. One of the important differences between the classical-to-quantum mapping and the converse quantum-to-classical mapping is that the Markovian dynamics of a short-range Ising model is mapped to a short-range quantum system, but the converse mapping from a short-range quantum system to a classical one results in long-range interactions. This leads to a difference in efficiencies that simulated annealing can be efficiently simulated by quantum annealing but the converse is not necessarily true. We conclude that quantum annealing is easier to implement and is more flexible than simulated annealing. We also point out that the present mapping can be extended to accommodate explicit time dependence of temperature, which is used to justify the quantum-mechanical analysis of simulated annealing by Somma, Batista, and Ortiz. Additionally, an alternative method to solve the nonequilibrium dynamics of the one-dimensional Ising model is provided through the classical-to-quantum mapping.

Nishimori, Hidetoshi; Tsuda, Junichi; Knysh, Sergey

2015-01-01

188

Photo annealing effect on p-doped inverted organic solar cell  

NASA Astrophysics Data System (ADS)

We report the transient positive photo annealing effect in which over 600% boost of power conversion efficiency was observed in inverted organic photovoltaic devices (OPV) made from P3HT/PCBM by spray method, after 2 hrs of constant solar AM 1.5 irradiation at low temperature. This is opposite to usual photodegradation of OPV, and cannot be explained by thermal activation alone since the mere temperature effect could only account for 30% of the enhancement. We have investigated the temperature dependence, cell geometry, oxygen influence, and conclude that, for p-doped active layer at room temperature, the predominant mechanism is photo-desorption of O2, which eliminates electron traps and reduces space charge screening. As temperature decreases, thermal activation and deep trap-state filling start to show noticeable effect on the enhancement of photocurrent at intermediate low temperature (T = 125 K). At very low temperature, the dominant mechanism for photo annealing is trap-filling, which significantly reduces recombination between free and trapped carriers. At all temperature, photo annealing effect depends on illumination direction from cathode or anode. We also explained the large fluctuation of photocurrent by the capture/reemit of trapped electrons from shallow electron traps of O2- generated by photo-doping. Our study has demonstrated the dynamic process of photo-doping and photo-desorption, and shown that photo annealing in vacuum can be an efficient method to improve OPV device efficiency.

Lafalce, Evan; Toglia, Patrick; Lewis, Jason E.; Jiang, Xiaomei

2014-06-01

189

Photo annealing effect on p-doped inverted organic solar cell  

SciTech Connect

We report the transient positive photo annealing effect in which over 600% boost of power conversion efficiency was observed in inverted organic photovoltaic devices (OPV) made from P3HT/PCBM by spray method, after 2?hrs of constant solar AM 1.5 irradiation at low temperature. This is opposite to usual photodegradation of OPV, and cannot be explained by thermal activation alone since the mere temperature effect could only account for 30% of the enhancement. We have investigated the temperature dependence, cell geometry, oxygen influence, and conclude that, for p-doped active layer at room temperature, the predominant mechanism is photo-desorption of O{sub 2}, which eliminates electron traps and reduces space charge screening. As temperature decreases, thermal activation and deep trap-state filling start to show noticeable effect on the enhancement of photocurrent at intermediate low temperature (T?=?125?K). At very low temperature, the dominant mechanism for photo annealing is trap-filling, which significantly reduces recombination between free and trapped carriers. At all temperature, photo annealing effect depends on illumination direction from cathode or anode. We also explained the large fluctuation of photocurrent by the capture/reemit of trapped electrons from shallow electron traps of O{sub 2}{sup -} generated by photo-doping. Our study has demonstrated the dynamic process of photo-doping and photo-desorption, and shown that photo annealing in vacuum can be an efficient method to improve OPV device efficiency.

Lafalce, Evan; Toglia, Patrick; Lewis, Jason E.; Jiang, Xiaomei, E-mail: xjiang@usf.edu [Department of Physics, University of South Florida, Tampa, Florida 33620 (United States)

2014-06-28

190

The local crystallization in nanoscale diamond-like carbon films during annealing  

NASA Astrophysics Data System (ADS)

The local crystallization during annealing at 600 °C in nanoscale diamond-like carbon coatings films grown by pulsed vacuum-arc deposition method was observed using modern techniques of high-resolution transmission electron microscopy. The crystallites formed by annealing have a face-centred cubic crystal structure and grow in the direction [ 0 1 ¯ 1 ¯ ] as a normal to the film surface. The number and size of the crystallites depend on the initial values of the intrinsic stresses before annealing, which in turn depend on the conditions of film growth. The sizes of crystallites are 10 nm for films with initial compressive stresses of 3 GPa and 17 nm for films with initial compressive stresses of 12 GPa. Areas of local crystallization arising during annealing have a structure different from the graphite. Additionally, the investigation results of the structure of nanoscale diamond-like carbon coatings films using Raman spectroscopy method are presented, which are consistent with the transmission electron microscopy research results.

Kolpakov, A. Ya.; Poplavsky, A. I.; Galkina, M. E.; Manokhin, S. S.; Gerus, J. V.

2014-12-01

191

Lattice site location and annealing behavior of implanted Ca and Sr in GaN  

NASA Astrophysics Data System (ADS)

We report on the lattice location of ion-implanted Ca and Sr in thin films of single-crystalline wurtzite GaN. Using the emission channeling technique the angular distributions of ?- particles emitted by the radioactive isotopes 45Ca (t1/2=163.8 d) and 89Sr (t1/2=50.53 d) were monitored with a position-sensitive detector following 60 keV room-temperature implantation. Our experiments give direct evidence that ˜90% of Ca and >60% of Sr atoms were occupying substitutional Ga sites with root mean square displacements of the order of 0.15-0.30 Å, i.e., larger than the expected thermal vibration amplitude of 0.074 Å. Annealing the Ca implanted samples at 1100-1350 °C in high-pressure N2 atmosphere resulted in a better incorporation into the substitutional Ga site. The Sr implanted sample showed a small decrease in rms displacements for vacuum annealing up to 900 °C, while the substitutional fraction remained nearly constant. The annealing behavior of the rms displacements can explain why annealing temperatures above 1100 °C are needed to achieve electrical and optical activations, despite the fact that the majority of the acceptors are already located on Ga sites immediately after ion implantation.

De Vries, B.; Vantomme, A.; Wahl, U.; Correia, J. G.; Araújo, J. P.; Lojkowski, W.; Kolesnikov, D.

2006-07-01

192

Effect of annealing on structural and optical properties of diamond-like nanocomposite thin films  

NASA Astrophysics Data System (ADS)

The annealing effect on structural and optical properties of the Diamond-like Nanocomposite (DLN) thin film deposited on glass substrate by Plasma Assisted Chemical Vapor Deposition (PACVD) method has been investigated. The films were annealed at temperature ranging from 300 to 600 °C, with 100 °C interval for 9 minutes by rapid thermal process (RTP) under vacuum. The structural changes of the annealed films have been studied using Fourier transform infrared spectroscopy (FTIR), Raman spectroscopy, Scanning Electron Microscope (SEM), and optical parameters have been determined using transmittance and reflectance spectra in UV-UIS-NIR range. The result shows that the refractive index increases gradually from 1.79 to 2.84 with annealing temperature due to out-diffusion of H by breaking Si-H and C-H bond leads to Si-C bond, i.e. more cross linking structure. In higher temperature range, graphitization also enhanced the refractive index. However, the optical band gap at up to 400 °C initially increases from 3.05 to 3.20 eV and then decreases due to graphitization. The film has a great potential to be used as anti-reflection coating (ARC) on silicon-based solar cell.

Jana, Sukhendu; Das, Sayan; De, Debasish; Gangopadhyay, Utpal; Ghosh, Prajit; Mondal, Anup

2014-03-01

193

Influence of in-situ annealing ambient on p-type conduction in dual ion beam sputtered Sb-doped ZnO thin films  

SciTech Connect

Sb-doped ZnO (SZO) films were deposited on c-plane sapphire substrates by dual ion beam sputtering deposition system and subsequently annealed in-situ in vacuum and in various proportions of O{sub 2}/(O{sub 2} + N{sub 2})% from 0% (N{sub 2}) to 100% (O{sub 2}). Hall measurements established all SZO films were p-type, as was also confirmed by typical diode-like rectifying current-voltage characteristics from p-ZnO/n-ZnO homojunction. SZO films annealed in O{sub 2} ambient exhibited higher hole concentration as compared with films annealed in vacuum or N{sub 2} ambient. X-ray photoelectron spectroscopic analysis confirmed that Sb{sup 5+} states were more preferable in comparison to Sb{sup 3+} states for acceptor-like Sb{sub Zn}-2V{sub Zn} complex formation in SZO films.

Pandey, Sushil Kumar; Kumar Pandey, Saurabh; Awasthi, Vishnu; Mukherjee, Shaibal [Hybrid Nanodevice Research Group (HNRG), Discipline of Electrical Engineering, Indian Institute of Technology, Indore 453441 (India)] [Hybrid Nanodevice Research Group (HNRG), Discipline of Electrical Engineering, Indian Institute of Technology, Indore 453441 (India); Gupta, M.; Deshpande, U. P. [University Grants Commission Department of Atomic Energy (UGC DAE) Consortium for Scientific Research, Indore (India)] [University Grants Commission Department of Atomic Energy (UGC DAE) Consortium for Scientific Research, Indore (India)

2013-08-12

194

Transport phenomena in porous media  

NASA Astrophysics Data System (ADS)

The Advanced Study Institute on Fundamentals of Transport Phenomena in Porous Media, held July 14-23, 1985 in Newark, Del. and directed by Jacob Bear (Israel Institute of Technology, Haifa) and M. Yavuz Corapcioglu (City College of New York), under the auspices of NATO, was a sequel to the NATO Advanced Study Institute (ASI) held in 1982 (proceedings published as Fundamentals of Transport Phenomena in Porous Media, J. Bear, and M.Y. Corapcioglu (Ed.), Martinus Nijhoff, Dordrecht, the Netherlands, 1984). The meeting was attended by 106 participants and lecturers from 21 countries.As in the first NATO/ASI, the objective of this meeting—which was a combination of a conference of experts and a teaching institute— was to present and discuss selected topics of transport in porous media. In selecting topics and lecturers, an attempt was made to bridge the gap that sometimes exists between research and practice. An effort was also made to demonstrate the unified approach to the transport of mass of a fluid phase, components of a fluid phase, momentum, and heat in a porous medium domain. The void space may be occupied by a single fluid phase or by a number of such phases; each fluid may constitute a multicomponent system; the solid matrix may be deformable; and the whole process of transport in the system may take place under nonisothermal conditions, with or without phase changes. Such phenomena are encountered in a variety of disciplines, e.g., petroleum engineering, civil engineering (in connection with groundwater flow and contamination), soil mechanics, and chemical engineering. One of the goals of the 1985 NATO/ASI, as in the 1982 institute, was to bring together experts from all these disciplines and enhance communication among them.

Bear, Jacob; Corapcioglu, M. Yavuz

195

Gravitational anomaly and transport phenomena.  

PubMed

Quantum anomalies give rise to new transport phenomena. In particular, a magnetic field can induce an anomalous current via the chiral magnetic effect and a vortex in the relativistic fluid can also induce a current via the chiral vortical effect. The related transport coefficients can be calculated via Kubo formulas. We evaluate the Kubo formula for the anomalous vortical conductivity at weak coupling and show that it receives contributions proportional to the gravitational anomaly coefficient. The gravitational anomaly gives rise to an anomalous vortical effect even for an uncharged fluid. PMID:21797593

Landsteiner, Karl; Megías, Eugenio; Pena-Benitez, Francisco

2011-07-01

196

Measurements design and phenomena discrimination  

E-print Network

The construction of measurements suitable for discriminating signal components produced by phenomena of different types is considered. The required measurements should be capable of cancelling out those signal components which are to be ignored when focusing on a phenomenon of interest. Under the hypothesis that the subspaces hosting the signal components produced by each phenomenon are complementary, their discrimination is accomplished by measurements giving rise to the appropriate oblique projector operator. The subspace onto which the operator should project is selected by nonlinear techniques in line with adaptive pursuit strategies.

Laura Rebollo-Neira

2009-08-05

197

Improving Simulated Annealing by Replacing Its Variables with Game-Theoretic Utility Maximizers  

NASA Technical Reports Server (NTRS)

The game-theory field of Collective INtelligence (COIN) concerns the design of computer-based players engaged in a non-cooperative game so that as those players pursue their self-interests, a pre-specified global goal for the collective computational system is achieved as a side-effect. Previous implementations of COIN algorithms have outperformed conventional techniques by up to several orders of magnitude, on domains ranging from telecommunications control to optimization in congestion problems. Recent mathematical developments have revealed that these previously developed algorithms were based on only two of the three factors determining performance. Consideration of only the third factor would instead lead to conventional optimization techniques like simulated annealing that have little to do with non-cooperative games. In this paper we present an algorithm based on all three terms at once. This algorithm can be viewed as a way to modify simulated annealing by recasting it as a non-cooperative game, with each variable replaced by a player. This recasting allows us to leverage the intelligent behavior of the individual players to substantially improve the exploration step of the simulated annealing. Experiments are presented demonstrating that this recasting significantly improves simulated annealing for a model of an economic process run over an underlying small-worlds topology. Furthermore, these experiments reveal novel small-worlds phenomena, and highlight the shortcomings of conventional mechanism design in bounded rationality domains.

Wolpert, David H.; Bandari, Esfandiar; Tumer, Kagan

2001-01-01

198

Natural phenomena hazards, Hanford Site, Washington  

SciTech Connect

This document presents the natural phenomena hazard loads for use in implementing DOE Order 5480.28, Natural Phenomena Hazards Mitigation, and supports development of double-shell tank systems specifications at the Hanford Site in south-central Washington State. The natural phenomena covered are seismic, flood, wind, volcanic ash, lightning, snow, temperature, solar radiation, suspended sediment, and relative humidity.

Conrads, T.J.

1998-09-29

199

Investigation of Ni/Ta contacts on 4H silicon carbide upon thermal annealing  

NASA Astrophysics Data System (ADS)

Nickel and Tantalum thin films with 3:5 thickness ratios were deposited in succession onto 4H-SiC substrate at room temperature. The samples were then heated in situ in vacuum at 650, 800 or 950 °C for 30 min. Glancing angle X-ray diffraction (XRD), Auger electron spectroscopy (AES) and current-voltage ( I- V) technique were used for characterising the interfacial reactions and electrical properties. Amorphous Ni-Ta can be formed by solid-state reaction at 650 °C. The minor dissolved Ni in the Ta metal promotes the reaction between Ta and SiC. With increasing annealing temperature up to 950 °C, the dominant carbide changes from Ta 2C to TaC and a layer structure is developed. Electrical measurements show that ohmic contact is formed after annealing at or above 800 °C.

Cao, Y.; Pérez-García, S. A.; Nyborg, L.

2007-10-01

200

Thermal annealing and air exposing effect on the graphene/silicon Schottky junctions  

NASA Astrophysics Data System (ADS)

Graphene/silicon (Gr/Si) configurations form Schottky junctions and should be a promising structure for high-performance electronics and optoelectronics. Here we presented a study on the properties of Gr/Si Schottky junctions by thermal annealing and air exposing. It was found that the ideal factor and the Schottky barrier height were lowered after vacuum annealing and increased after exposing in air for several days. The modulation of the Schottky junctions was further used to tune their optoelectronic properties. The results exhibit that the open-circuit voltage of the junctions under light illumination was varied with the ideal factor. The work here should be helpful on developing high-performance Gr/Si electronics and optoelectronics.

Wang, Xiaojuan; Wang, Yuanyuan; Li, Dong; Zou, Liping; Zhang, Qichong; Zhou, Jun; Liu, Dongfang; Zhang, Zengxing

2015-01-01

201

Improved electron collection in fullerene via caesium iodide or carbonate by means of annealing in inverted organic solar cells  

NASA Astrophysics Data System (ADS)

Inverted organic photovoltaic cells (IOPVCs), based on the planar heterojunction C60/CuPc, were grown using MoO3 as anode buffer layer and CsI or Cs2CO3 as cathode buffer layer (CBL), the cathode being an ITO coated glass. Work functions, ?f, of treated cathode were estimated using the cyclic voltammetry method. It is shown that ?f of ITO covered with a Cs compounds is decreased. This decrease is amplified by the annealing. It is shown that the thermal deposition under vacuum of the CBL induces a partial decomposition of the caesium compounds. In parallel, the formation of a compound with the In of ITO is put in evidence. This reaction is amplified by annealing, which allows obtaining IOPVCs with improved efficiency. The optimum annealing conditions is 150 °C for 5 min.

El Jouad, Zouhair; Louarn, Guy; Praveen, Thappily; Predeep, Padmanabhan; Cattin, Linda; Bernède, Jean-Christian; Addou, Mohammed; Morsli, Mustapha

2014-05-01

202

Structural and magnetic properties of TiZrNi thin films prepared by magnetron sputtering and thermal annealing.  

PubMed

Distinctive thin layers of TiZr and Ni were deposited by using a magnetron sputtering method and a thermal annealing was applied to discover metallic films of quasicrystals. After a heat treatment in vacuum, 70 nm thick deposited layers were well mixed with nominal compositions of 49.7, 29.3 and 21.0 for Ti, Zr and Ni, respectively, which is very close with the one forming a quasicrystalline phase. The magnetization values were significantly decreased from 0.286 to 0.142 emu/mm3 at 2000 Oe, after annealing, while a shape of magnetic hysteresis was maintained. It is believed that a different magnetic behavior after thermal annealing is due to the homogeneous mixing of atomic elements and possible existence of a metastable phase. PMID:21138037

Shin, Hyemin; Choi, Soo-bin; Lee, Ik-jae; Yu, Chung-jong; Kim, Jae-yong

2010-11-01

203

A Simple Coaxial Ceramic Based Vacuum Window for Vacuum Transmission Line of ICRF System  

NASA Astrophysics Data System (ADS)

We present here a simple coaxial RF vacuum window designed for 200 kW power without any design complicacy and is simple to fabricate. It is achieved by sandwiching a UHV grade ceramic disk in between inner and outer straight conductors. The window has been designed and fabricated for use in the VTL section of ICRF system on ADITYA tokamak. The window has been modeled with CST Microwave Studio and transient analysis has been done for different scattering parameters. The window is found to be an excellent leak tight with leak rate better than 1.0×10-9 mbarl/s. Pressure test on window up to a 3 bar atmospheric pressure shows that it can also be used as a gas barrier in transmission lines. Low power VNA test shows a pleasing VSWR and insertion loss less than 1.07 and 0.05 dB respectively in the frequency range of 20-100MHz. Special care has been taken to minimize sharp edges to avoid pre-breakdown phenomena. Partial discharge tests at 50Hz shows an excellent result up to 24 kV peak and the observed discharge magnitude was less than 20 pC. The window shows the ultra high vacuum compatibility and it tested for high RF power at 29 MHz up to 80kW of power. This paper presents the design detail, tests conducted and the results obtained for the vacuum window.

Rathi, D.; Mishra, K.; Goerge, S.; Varia, A.; Kulkarni, S. V.

2011-12-01

204

Synthesis of large area, homogeneous, single layer graphene films by annealing amorphous carbon on Co and Ni  

Microsoft Academic Search

The synthesis of large area, homogenous, single layer graphene on cobalt (Co) and nickel (Ni) is reported. The process involves\\u000a vacuum annealing of sputtered amorphous carbon (a-C) deposited on Co\\/sapphire or Ni\\/sapphire substrates. The improved crystallinity\\u000a of the metal film, assisted by the sapphire substrate, proves to be the key to the quality of as-grown graphene film. The\\u000a crystallinity of

Carlo M. Orofeo; Hiroki Ago; Baoshan Hu; Masaharu Tsuji

2011-01-01

205

Avoiding Death by Vacuum  

NASA Astrophysics Data System (ADS)

The two-Higgs doublet model (2HDM) can have two electroweak breaking, CP-conserving, minima. The possibility arises that the minimum which corresponds to the known elementary particle spectrum is metastable, a possibility we call the "panic vacuum". We present analytical bounds on the parameters of the softly broken Peccei-Quinn 2HDM which are necessary and sufficient conditions to avoid this possibility. We also show that, for this particular model, the current LHC data already tell us that we are necessarily in the global minimum of the theory, regardless of any cosmological considerations about the lifetime of the false vacua.

Barroso, A.; Ferreira, P. M.; Ivanov, I.; Santos, R.; Silva, João P.

2013-07-01

206

What is vacuum?  

E-print Network

Vacuum can be defined with exact mathematical precision as the state which remains when a fermion, with all its special characteristics, is created out of absolutely nothing. The definition leads to a special form of relativistic quantum mechanics, which only requires the construction of a creation operator. This form of quantum mechanics is especially powerful for analytic calculation, at the same time as explaining, from first principles, many aspects of the Standard Model of particle physics. In particular, the characteristics of the weak, strong and electric interactions can be derived from the structure of the creation operator itself.

Peter Rowlands

2008-10-01

207

Origin of reverse annealing effect in hydrogen-implanted silicon  

SciTech Connect

In contradiction to conventional damage annealing, thermally annealed H-implanted Si exhibits an increase in damage or reverse annealing behavior, whose mechanism has remained elusive. In this work, we conclusively elucidate that the reverse annealing effect is due to the nucleation and growth of hydrogen-induced platelets. Platelets are responsible for an increase in the height and width of the channeling damage peak following increased isochronal anneals.

Di, Z. F.; Wang, Y. Q.; Nastasi, M. [Los Alamos National Laboratory, Los Alamos, New Mexico 87545 (United States); Theodore, N. David [Silicon Technology Solutions, Freescale Semiconductor Inc., Tempe, Arizona 85284 (United States)

2010-04-12

208

Origin of reverse annealing effect in hydrogen-implanted silicon  

SciTech Connect

In contradiction to conventional damage annealing, thermally annealed H-implanted Si exhibits an increase in damage or reverse annealing behavior, whose mechanism has remained elusive. On the basis of quantitative high resolution transmission electron microscopy combined with channeling Rutherford backscattering analysis, we conclusively elucidate that the reverse annealing effect is due to the nucleation and growth of hydrogen-induce platelets. Platelets are responsible for an increase in the height and width the channeling damage peak following increased isochronal anneals.

Di, Zengfeng [Los Alamos National Laboratory; Nastasi, Michael A [Los Alamos National Laboratory; Wang, Yongqiang [Los Alamos National Laboratory

2009-01-01

209

Uranium Pyrophoricity Phenomena and Prediction  

SciTech Connect

We have compiled a topical reference on the phenomena, experiences, experiments, and prediction of uranium pyrophoricity for the Hanford Spent Nuclear Fuel Project (SNFP) with specific applications to SNFP process and situations. The purpose of the compilation is to create a reference to integrate and preserve this knowledge. Decades ago, uranium and zirconium fires were commonplace at Atomic Energy Commission facilities, and good documentation of experiences is surprisingly sparse. Today, these phenomena are important to site remediation and analysis of packaging, transportation, and processing of unirradiated metal scrap and spent nuclear fuel. Our document, bearing the same title as this paper, will soon be available in the Hanford document system [Plys, et al., 2000]. This paper explains general content of our topical reference and provides examples useful throughout the DOE complex. Moreover, the methods described here can be applied to analysis of potentially pyrophoric plutonium, metal, or metal hydride compounds provided that kinetic data are available. A key feature of this paper is a set of straightforward equations and values that are immediately applicable to safety analysis.

DUNCAN, D.R.

2000-04-20

210

Fuzzy intervention in biological phenomena.  

PubMed

An important objective of modeling biological phenomena is to develop therapeutic intervention strategies to move an undesirable state of a diseased network toward a more desirable one. Such transitions can be achieved by the use of drugs to act on some genes/metabolites that affect the undesirable behavior. Due to the fact that biological phenomena are complex processes with nonlinear dynamics that are impossible to perfectly represent with a mathematical model, the need for model-free nonlinear intervention strategies that are capable of guiding the target variables to their desired values often arises. In many applications, fuzzy systems have been found to be very useful for parameter estimation, model development and control design of nonlinear processes. In this paper, a model-free fuzzy intervention strategy (that does not require a mathematical model of the biological phenomenon) is proposed to guide the target variables of biological systems to their desired values. The proposed fuzzy intervention strategy is applied to three different biological models: a glycolytic-glycogenolytic pathway model, a purine metabolism pathway model, and a generic pathway model. The simulation results for all models demonstrate the effectiveness of the proposed scheme. PMID:23221089

Nounou, Hazem N; Nounou, Mohamed N; Meskin, Nader; Datta, Aniruddha; Dougherty, Edward R

2012-01-01

211

Annealing effects on the structural, magnetic and electrical properties of the nanocrystalline Fe3O4 films  

NASA Astrophysics Data System (ADS)

Nowadays, the effective spin injection across the surface or interface between the magnetic injector and the insulating barrier is one of the key issues and big challenges in realizing potential spintronic devices. In this paper, we report the annealing effects on the structural, magnetic and electrical properties of nanocrystalline Fe3O4 films. The width and height of the tunnelling barrier in these nanocrystalline films can be adjusted by vacuum and/or air annealing. The structural, chemical states, magnetic and electrical measurements indicate a good stoichiometry of Fe3O4 for the vacuum annealed samples. While maintaining a high spin polarization, the resistivity, which is determined by the barrier width and height in Fe3O4 films, can be tuned over three orders of magnitude at room temperature by annealing. Resistivity over seven orders of magnitude is obtained from 108 to 300 K, which enables the nanocrystalline Fe3O4 to be a versatile spin injector matching with various doped semiconductors with different conductivities, and makes it a possible candidate for high-efficient magnetoelectronic devices.

Cheng, Yahui; Liu, Hui; Li, H. B.; Zheng, R. K.; Ringer, S. P.

2009-11-01

212

Unipolar resistive switching behaviors and mechanisms in an annealed Ni/ZrO2/TaN memory device  

NASA Astrophysics Data System (ADS)

The effects of Ni/ZrO2/TaN resistive switching memory devices without and with a 400?°C annealing process on switching properties are investigated. The devices exhibit unipolar resistive switching behaviors with low set and reset voltages because of a large amount of Ni diffusion with no reaction with ZrO2 after the annealing process, which is confirmed by ToF-SIMS and XPS analyses. A physical model based on a Ni filament is constructed to explain such phenomena. The device that undergoes the 400?°C annealing process exhibits an excellent endurance of more than 1.5? × ?104 cycles. The improvement can be attributed to the enhancement of oxygen ion migration along grain boundaries, which result in less oxygen ion consumption during the reset process. The device also performs good retention up to 105?s at 150?°C. Therefore, it has great potential for high-density nonvolatile memory applications.

Tsai, Tsung-Ling; Ho, Tsung-Han; Tseng, Tseung-Yuen

2015-01-01

213

R&D ERL: Vacuum  

SciTech Connect

The ERL Vacuum systems are depicted in a figure. ERL has eight vacuum volumes with various sets of requirements. A summary of vacuum related requirements is provided in a table. Five of the eight volumes comprise the electron beamline. They are the 5-cell Superconducting RF Cavity, Superconducting e-gun, injection, loop and beam dump. Two vacuum regions are the individual cryostats insulating the 5-cell Superconducting RF Cavity and the Superconducting e-gun structures. The last ERL vacuum volume not shown in the schematic is the laser transport line. The beamline vacuum regions are separated by electropneumatic gate valves. The beam dump is common with loop beamline but is considered a separate volume due to geometry and requirements. Vacuum in the 5-cell SRF cavity is maintained in the {approx}10{sup -9} torr range at room temperature by two 20 l/s ion pumps and in the e-gun SRF cavity by one 60 l/s ion pump. Vacuum in the SRF cavities operated at 2{sup o}K is reduced to low 10{sup -11} torr via cryopumping of the cavity walls. The cathode of the e-gun must be protected from poisoning, which can occur if vacuum adjacent to the e-gun in the injection line exceeds 10-11 torr range in the injection warm beamline near the e-gun exit. The vacuum requirements for beam operation in the loop and beam dump are 10-9 torr range. The beamlines are evacuated from atmospheric pressure to high vacuum level with a particulate free, oil free turbomolecular pumping cart. 25 l/s shielded ion pumps distributed throughout the beamlines maintain the vacuum requirement. Due to the more demanding vacuum requirement of the injection beamline proximate to the e-gun, a vacuum bakeout of the injection beamline is required. In addition, two 200 l/s diode ion pumps and supplemental pumping provided by titanium sublimation pumps are installed in the injection line just beyond the exit of the e-gun. Due to expected gas load a similar pumping arrangement is planned for the beam dump. The cryostat vacuum thermally insulating the SRF cavities need only reduce the convective heat load such that heat loss is primarily radiation through several layers of multi-layer insulation and conductive end-losses which are contained by 5{sup o}K thermal transitions. Prior to cool down rough vacuum {approx}10{sup -5} torr range is established and maintained by a dedicated turbomolecular pump station. Cryopumping by the cold mass and heat shields reduces the insulating vacuum to 10{sup -7} torr range after cool down.

Mapes, M.; Smart, L.; Weiss, D.; Steszyn, A.; Todd, R.

2010-01-01

214

Crack paths, microstructure, and fatigue crack growth in annealed and cold-rolled AISI 304 stainless steels  

NASA Astrophysics Data System (ADS)

To assist in the understanding of micromechanisms for corrosion fatigue crack growth in metastable austenitic steels, the relationships between the crack paths and the underlying microstructure were investigated for annealed and cold-rolled (CR) 304 stainless steels that had been tested in a deaerated 3.5 pct NaCl solution, air, and vacuum. Corrosion fatigue in the deleterious environments (3.5 pct NaCl and air) was brittle and occurred primarily by {001}? and other unidentified, quasi-cleavage (QC), accompanied by preferential cracking along {111}? twin and grain boundaries. In contrast, fatigue cracking in vacuum was ductile, fully transgranular, and noncrystallographic. Transformation to alpha prime (?'-) martensite by fatigue was found to be essentially complete in the CR steel, which contained ?-martensite, and in the annealed steel tested in vacuum, but was substantially less in the annealed steel tested in air and 3.5 pct NaCl solution. These results, taken in conjunction with the crack growth and electrochemical reaction data, support hydrogen embrittlement (HE) as the mechanism for corrosion fatigue crack growth in 304 stainless steels in 3.5 pct NaCl solution. Martensitic transformation appears not to be the only responsible factor for embrittlement. Other microstructural components, such as twin and grain boundaries, slip bands, and cold work-induced lattice defects, may play more important roles in enhancing crack growth rates.

Gao, Ming; Chen, Shuchun; Wei, Robert P.

1992-01-01

215

Pulsed and continuous wave solid phase laser annealing of electrodeposited CuInSe2 thin films  

NASA Astrophysics Data System (ADS)

Cu(In,Ga)Se2 (CIGS) thin film photovoltaic absorber layers are primarily synthesized by vacuum based techniques at industrial scale. In this work, we investigate non-vacuum film synthesis by electrochemical deposition coupled with pulsed laser annealing (PLA) and or continuous wave laser annealing (CWLA) using 1064 nm laser. PLA results indicate that at high fluence (>=100 mJ/cm2) CuInSe2 films melt and dewet on both Mo and Cu substrates. In the submelt PLA regime (<=70 mJ/cm2) no change in XRD results is recorded. However CWLA at 50 W/cm2 for up to 45 s does not result in melting or dewetting of the film. XRD and Raman data indicate more than 80% reduction in full width at half maximum (FWHM) in their respective main peaks for annealing time of 15 s or more. No other secondary phases are observed in XRD or Raman spectrum. These results might help us in setting up the foundation for processing CIGS through an entirely non-vacuum process.

Bhatia, Ashish; Meadows, Helen; Crossay, Alexandre; Dale, Phillip J.; Scarpulla, Michael A.

2012-10-01

216

The vacuum arc centrifuge  

NASA Astrophysics Data System (ADS)

The separation of elements and isotopes by means of rotating magnetized plasma columns using a laser-triggered vacuum arc centrifuge is described. This vacuum arc centrifuge is sustained by the erosion and ionization of the cathode material, thus producing relatively pure, highly ionized, rotating plasma columns of the cathode material. Any solid metal, or mixture of metals, can be converted into plasma, and the constituent isotopes partially separated in the centrifuge, by fabricating the arc cathode out of the desired metals. The device also offers the possibility of operation with nonconducting solid elements or compounds by imbedding the desired substance in a conducting matrix. A wide variety of metals and combinations of metals were studied, ranging from C through Cu to Cd/Sn. Typical angular rotation frequencies of approx. 100,000 rad/sec were measured, with concomitant enrichments up to a factor of two for Cu 65. The device in its present form is not a viable source of partially enriched stable isotopes at a competitive cost.

Krishnan, M.; Hirshfield, J. L.

217

The LHC Vacuum System  

E-print Network

The Large Hadron Collider (LHC) at CERN, involves two proton storage rings with colliding beams of 7 TeV. The machine will be housed in the existing LEP tunnel and requires 16 m long superconducting b ending magnets. The vacuum chamber will be the inner wall of the cryostat and hence at the temperature of the magnet cold bore, i.e. at 1.9 K and therefore a very good cryopump. To reduce the cryogeni c power consumption, the heat load from synchrotron radiation and from the image currents in the vacuum chamber will be absorbed on a 'beam screen', which operates between 5 and 20 K, inserted in the magnet cold bore. The design pressure necessary for operation must provide a lifetime of several days and a further stringent requirement comes from the power deposition in the superconducting magnet coils due to protons scattered on the residual gas which could lead to a magnet quench. Cryopumping of gas on the cold surfaces provides the necessary low gas densities but it must be ensured that the vapour pressure of cr...

Gröbner, Oswald

1998-01-01

218

LHC vacuum system  

E-print Network

The Large Hadron Collider (LHC) project, now in the advanced construction phase at CERN, comprises two proton storage rings with colliding beams of 7-TeV energy. The machine is housed in the existing LEP tunnel with a circumference of 26.7 km and requires a bending magnetic field of 8.4 T with 14-m long superconducting magnets. The beam vacuum chambers comprise the inner 'cold bore' walls of the magnets. These magnets operate at 1.9 K, and thus serve as very good cryo-pumps. In order to reduce the cryogenic power consumption, both the heat load from synchrotron radiation emitted by the proton beams and the resistive power dissipation by the beam image currents have to be absorbed on a 'beam screen', which operates between 5 and 20 K and is inserted inside the vacuum chamber. The design of this beam screen represents a technological challenge in view of the numerous and often conflicting requirements and the very tight mechanical tolerances imposed. The synchrotron radiation produces strong outgassing from the...

Gröbner, Oswald

1999-01-01

219

Direct observation of vacuum fluctuations in a spinor Bose-Einstein condensate  

E-print Network

The nature of the vacuum state and its fluctuations constitutes one of the most fascinating aspects of modern physics. Despite their non-intuitive character, vacuum fluctuations play an important role for our understanding of nature. Specifically, the parametric amplification of such fluctuations is crucial for phenomena ranging from optical parametric down-conversion to stimulated positronium annihilation, and boson creation in Universe inflation. Spinor Bose-Einstein condensates, consisting of atoms with non-zero total spin, provide an optimal system for the investigation of the vacuum state, since vacuum fluctuations can dominate classical fluctuations in the spin dynamics of these magnetic superfluids. Here we explore the amplification of vacuum fluctuations in gaseous spinor condensates in an unstable spin configuration. We observe strong instability resonances in the spinor condensate, induced by the confinement of the atomic ensemble. Our work shows that it is crucial for the understanding of spinor dy...

Klempt, Carsten; Gebreyesus, Gebremedhn; Scherer, Manuel; Henninger, Thorsten; Hyllus, Philipp; Ertmer, Wolfgang; Santos, Luis; Arlt, Jan

2009-01-01

220

Observation of Vacuum Fluctuations in a Spinor Bose-Einstein Condensate  

NASA Astrophysics Data System (ADS)

The nature of the vacuum state and its fluctuations constitutes one of the most fascinating aspects of modern physics. In particular, the parametric amplification of such fluctuations is crucial for phenomena ranging from optical parametric down-conversion1 to stimulated positronium annihilation,2 and boson creation in Universe inflation.3 Spinor Bose-Einstein condensates,4-7 consisting of atoms with non-zero total spin, provide an optimal system for the investigation of the vacuum state.8,9 Here we describe the amplification of vacuum fluctuations in gaseous spinor condensates in an unstable spin configuration. We observe strong instability resonances in the spinor condensate,10 induced by the confinement of the atomic ensemble. On these resonances we conclusively demonstrate that the system can act as a parametric amplifier for vacuum fluctuations,11 providing a new microscope to investigate the vacuum state and a promising method for entanglement and squeezing production in matter waves.

Klempt, C.; Topic, O.; Gebreyesus, G.; Scherer, M.; Henninger, T.; Hyllus, P.; Ertmer, W.; Santos, L.; Arlt, J.

2010-02-01

221

On thermionic emission and the use of vacuum tubes in the advanced physics laboratory  

NASA Astrophysics Data System (ADS)

Two methods are outlined for measuring the charge-to-mass ratio e /me of the electron using thermionic emission as exploited in vacuum tube technology. One method employs the notion of the space charge in the vacuum tube diode as described by the Child-Langmuir equation; the other method uses the electron trajectories in vacuum tube pentodes with cylindrical electrodes under conditions of orthogonally related electric and magnetic fields (the Hull magnetron method). The vacuum diode method gave e /me=1.782±0.166×10+11 C/kg (averaged over the vacuum diodes studied), and the Hull magnetron method gave e /me=1.779±0.208×10+11 C/kg (averaged over both pentodes and the anode voltages studied). These methods afford opportunities for students to determine the e /me ratio without using the Bainbridge tube method and to become familiar with phenomena not normally covered in a typical experimental methods curriculum.

Angiolillo, Paul J.

2009-12-01

222

The effect of annealing on the photoluminescence of epitaxial DMe-PTCDI multilayers on Ag(110)  

Microsoft Academic Search

Epitaxial multilayer structures of DMe-PTCDI (2,9-dimethyl-antra[2,1,9-def:6,5,10-d?e?f?]diisoquinoline-1,3,8,10-tetrone) on Ag(110) were prepared by molecular beam epitaxy. Photoluminescence spectra obtained under ultra high vacuum (UHV) conditions of the multilayers show significant polarisation dependence. By combining this result with a real space model derived from low energy electron diffraction (LEED) measurements the molecular transition dipole moment was determined. During an annealing process the fluorescence

A. H. Schäfer; C. Seidel; H. Fuchs

2000-01-01

223

Vacuum disconnectors an application study  

Microsoft Academic Search

The ageing of vacuum interrupters with combined functions of disconnector and circuit-breaker or switch is studied for compact shielded solid insulated switchgear. Different prototypes are manufactured to investigate the influence of contact materials and contact designs. A test program is presented that realistically represents the ageing as described in the standards. The feasibility to create vacuum disconnecting circuit-breakers, vacuum switch-disconnectors

H. Schellekens; T. Shioiri; M. Homma; P. Picot; K. Sasage; D. Mazzucchi

2010-01-01

224

Portable vacuum object handling device  

DOEpatents

The disclosure relates to a portable device adapted to handle objects which are not to be touched by hand. A piston and bore wall form a vacuum chamber communicating with an adaptor sealably engageable with an object to be lifted. The piston is manually moved and set to establish vacuum. A valve is manually actuatable to apply the vacuum to lift the object. 1 fig.

Anderson, G.H.

1983-08-09

225

Low partial discharge vacuum feedthrough  

NASA Technical Reports Server (NTRS)

Relatively discharge free vacuum feedthrough uses silver-plated copper conductor jacketed by carbon filled silicon semiconductor to reduce concentrated electric fields and minimize occurrence of partial discharge.

Benham, J. W.; Peck, S. R.

1979-01-01

226

Vacuum insulation on the moon  

NASA Astrophysics Data System (ADS)

This paper presents recent concepts and analysis on vacuum insulation issues in the lunar environment, including dust initiated breakdown, thermal management, gas contamination, and solar radiation effects.

Gordon, Lloyd B.; Gaustad, Krista L.

1994-05-01

227

Onset phenomena in MPD thrusters  

NASA Technical Reports Server (NTRS)

An experimental study has clarified some aspects of MPD thruster onset phenomena. The steep increase in terminal voltage that occurs as the onset current is approached may have different causes, depending on the propellant injection geometry. For propellant injection at the cathode radius, terminal voltage increase corresponds to a growing anode fall voltage; for injection at a larger radius, the increase is related to the back emf in the near-cathode plasma. The formation of the onset current pattern within the arc has been mapped experimentally as the thruster responds to an input current step which rises from below onset to the onset value. The appearance of terminal voltage hash at onset correlates with the extension into the exhaust region of a significant fraction of the arc current.

Barnett, J. W.; Jahn, R. G.

1985-01-01

228

Unidentified phenomena - Unusual plasma behavior?  

NASA Astrophysics Data System (ADS)

The paper describes observations of a phenomenon belonging to the UFO category and the possible causes of these events. Special attention is given to an event which occurred during the night of September 19-20, 1974, when a huge 'star' was observed over Pertrozavodsk (Russia), consisting of a bright-white luminous center, emitting beams of light, and a less bright light-blue shell. The star gradually formed a cometlike object with a tail consisting of beams of light and started to descend. It is suggested that this event was related to cosmic disturbances caused by an occurrence of unusually strong solar flares. Other examples are presented that relate unusual phenomena observed in space to the occurrence of strong magnetic turbulence events.

Avakian, S. V.; Kovalenok, V. V.

1992-06-01

229

Emergent Phenomena at Oxide Interfaces  

SciTech Connect

Transition metal oxides (TMOs) are an ideal arena for the study of electronic correlations because the s-electrons of the transition metal ions are removed and transferred to oxygen ions, and hence the strongly correlated d-electrons determine their physical properties such as electrical transport, magnetism, optical response, thermal conductivity, and superconductivity. These electron correlations prohibit the double occupancy of metal sites and induce a local entanglement of charge, spin, and orbital degrees of freedom. This gives rise to a variety of phenomena, e.g., Mott insulators, various charge/spin/orbital orderings, metal-insulator transitions, multiferroics, and superconductivity. In recent years, there has been a burst of activity to manipulate these phenomena, as well as create new ones, using oxide heterostructures. Most fundamental to understanding the physical properties of TMOs is the concept of symmetry of the order parameter. As Landau recognized, the essence of phase transitions is the change of the symmetry. For example, ferromagnetic ordering breaks the rotational symmetry in spin space, i.e., the ordered phase has lower symmetry than the Hamiltonian of the system. There are three most important symmetries to be considered here. (i) Spatial inversion (I), defined as r {yields} -r. In the case of an insulator, breaking this symmetry can lead to spontaneous electric polarization, i.e. ferroelectricity, or pyroelectricity once the point group belongs to polar group symmetry. (ii) Time-reversal symmetry (T) defined as t {yields} -t. In quantum mechanics, the time-evolution of the wave-function {Psi} is given by the phase factor e{sup -iEt/{h_bar}} with E being the energy, and hence time-reversal basically corresponds to taking the complex conjugate of the wave-function. Also the spin, which is induced by the 'spinning' of the particle, is reversed by time-reversal. Broken T-symmetry is most naturally associated with magnetism, since the spin operator changes sign with T-operation. (iii) Gauge symmetry (G), which is associated with a change in the phase of the wave-function as {Psi} {yields} e{sup i{theta}}{Psi}. Gauge symmetry is connected to the law of charge conservation, and broken G-symmetry corresponds to superconductivity/superfluidity. To summarize, the interplay among these electronic degrees of freedom produces various forms of symmetry breaking patterns of I, T, and G, leading to novel emergent phenomena, which can appear only by the collective behavior of electrons and cannot be expected from individual electrons. Figure 1 shows this schematically by means of several representative phenomena. From this viewpoint, the interfaces of TMOs offer a unique and important laboratory because I is already broken by the structure itself, and the detailed form of broken I-symmetry can often be designed. Also, two-dimensionality usually enhances the effects of electron correlations by reducing their kinetic energy. These two features of oxide interfaces produce many novel effects and functions that cannot be attained in bulk form. Given that the electromagnetic responses are a major source of the physical properties of solids, and new gauge structures often appear in correlated electronic systems, we put 'emergent electromagnetism' at the center of Fig. 1.

Hwang, H.Y.

2012-02-16

230

Simulation of Storm Occurrences Using Simulated Annealing.  

NASA Astrophysics Data System (ADS)

Modeling storm occurrences has become a vital part of hurricane prediction. In this paper, a method for simulating event occurrences using a simulated annealing algorithm is described. The method is illustrated using annual counts of hurricanes and of tropical storms in the Atlantic Ocean and Gulf of Mexico. Simulations closely match distributional properties, including possible correlations, in the historical data. For hurricanes, traditionally used Poisson and negative binomial processes also predict univariate properties well, but for tropical storms parametric methods are less successful. The authors determined that simulated annealing replicates properties of both series. Simulated annealing can be designed so that simulations mimic historical distributional properties to whatever degree is desired, including occurrence of extreme events and temporal patterning.

Lokupitiya, Ravindra S.; Borgman, Leon E.; Anderson-Sprecher, Richard

2005-11-01

231

Silicon nanoparticles formation in annealed SiO/SiO 2 multilayers  

NASA Astrophysics Data System (ADS)

We present a study on amorphous SiO/SiO 2 superlattice performed by grazing-incidence small-angle X-ray scattering (GISAXS). Amorphous SiO/SiO 2 superlattices were prepared by high-vacuum evaporation of 3 nm thin films of SiO and SiO 2 (10 layers each) onto Si(1 0 0) substrate. After the deposition, samples were annealed at 1100 °C for 1 h in vacuum, yielding to Si nanocrystals formation. Using a Guinier approximation, the shape and the size of the crystals were obtained. The size of the growing nanoparticles in the direction perpendicular to the film surface is well controlled by the bilayer thickness. However, their size varies more significantly in the direction parallel to the film surface.

Kova?evi?, I.; Dub?ek, P.; Duguay, S.; Zorc, H.; Radi?, N.; Pivac, B.; Slaoui, A.; Bernstorff, S.

2007-04-01

232

Effects of annealing in Be/W and Be/C bilayers deposited on Si(0 0 1) substrates with Fe buffer layers  

NASA Astrophysics Data System (ADS)

Atomic intermixing processes in relation to structural aspects and phase formation in Be based thin films subjected to different annealing treatments simulating the case of re-deposited layered structures on plasma facing components in nuclear fusion devices are reported. Accordingly, bilayers of Be/W and Be/C have been deposited on Si(0 0 1) substrates with Fe buffer layers. The Fe films have been prepared by radiofrequency sputtering and further processed by annealing in hydrogen atmosphere at 300 °C, for 90 min, at a pressure of 10 bars of H2. After the Be/W and Be/C bilayer deposition by means of thermionic vacuum arc method, annealing in vacuum at 600 °C, for 10 min has been applied to the complex structures. The influence of annealing on the phase composition and atomic intermixing processes in the complex structures has been studied by means of X-ray photoelectron spectroscopy (XPS) and conversion electron Mössbauer spectroscopy (CEMS). The layered structures present an oxidation gradient with oxide phases in the uppermost layers and non-oxidized phases in the lower layers, as observed from the XPS data. The CEMS results revealed that the as-deposited structures contain a main metallic Fe phase and secondary superparamagnetic Fe oxide phases at the Fe/Be interface, while annealed samples present a large contribution of Fe-Be and Fe-C mixtures. The annealing treatment induces considerable atomic interdiffusion, strongly dependent on the nature of the upper layer. In the case of Be/W system, the annealing provides a much rougher Be/W interface, while in case of the Be/C structure, the annealing treatment only homogenize the structure over the whole depth.

Schinteie, G.; Greculeasa, S. G.; Palade, P.; Lungu, G. A.; Porosnicu, C.; Jepu, I.; Lungu, C. P.; Filoti, G.; Kuncser, V.

2015-02-01

233

Effect of heat processing on color and annealing of vacuum compression quartz glass  

Microsoft Academic Search

We observed the disappearance of the smoky semitransparent inclusions, and also the dark-brown coloration when the glass was reheated and at a temperature close to the softening temperature, and during rapid cooling in air. The thermal method of eliminating the inclusions and colorations is simpler and quite effective. However, during sudden cooling the glass develops serious stresses. With the aim

F. Ya. Borodai; L. I. Dedukhova

1967-01-01

234

PREFACE Integrability and nonlinear phenomena Integrability and nonlinear phenomena  

NASA Astrophysics Data System (ADS)

Back in 1967, Clifford Gardner, John Greene, Martin Kruskal and Robert Miura published a seminal paper in Physical Review Letters which was to become a cornerstone in the theory of integrable systems. In 2006, the authors of this paper received the AMS Steele Prize. In this award the AMS pointed out that `In applications of mathematics, solitons and their descendants (kinks, anti-kinks, instantons, and breathers) have entered and changed such diverse fields as nonlinear optics, plasma physics, and ocean, atmospheric, and planetary sciences. Nonlinearity has undergone a revolution: from a nuisance to be eliminated, to a new tool to be exploited.' From this discovery the modern theory of integrability bloomed, leading scientists to a deep understanding of many nonlinear phenomena which is by no means reachable by perturbation methods or other previous tools from linear theories. Nonlinear phenomena appear everywhere in nature, their description and understanding is therefore of great interest both from the theoretical and applicative point of view. If a nonlinear phenomenon can be represented by an integrable system then we have at our disposal a variety of tools to achieve a better mathematical description of the phenomenon. This special issue is largely dedicated to investigations of nonlinear phenomena which are related to the concept of integrability, either involving integrable systems themselves or because they use techniques from the theory of integrability. The idea of this special issue originated during the 18th edition of the Nonlinear Evolution Equations and Dynamical Systems (NEEDS) workshop, held at Isola Rossa, Sardinia, Italy, 16-23 May 2009 (http://needs-conferences.net/2009/). The issue benefits from the occasion offered by the meeting, in particular by its mini-workshops programme, and contains invited review papers and contributed papers. It is worth pointing out that there was an open call for papers and all contributions were peer reviewed according to the standards of the journal. The selection of papers in this issue aims to bring together recent developments and findings, even though it consists of only a fraction of the impressive developments in recent years which have affected a broad range of fields, including the theory of special functions, quantum integrable systems, numerical analysis, cellular automata, representations of quantum groups, symmetries of difference equations, discrete geometry, among others. The special issue begins with four review papers: Integrable models in nonlinear optics and soliton solutions Degasperis [1] reviews integrable models in nonlinear optics. He presents a number of approximate models which are integrable and illustrates the links between the mathematical and applicative aspects of the theory of integrable dynamical systems. In particular he discusses the recent impact of boomeronic-type wave equations on applications arising in the context of the resonant interaction of three waves. Hamiltonian PDEs: deformations, integrability, solutions Dubrovin [2] presents classification results for systems of nonlinear Hamiltonian partial differential equations (PDEs) in one spatial dimension. In particular he uses a perturbative approach to the theory of integrability of these systems and discusses their solutions. He conjectures universality of the critical behaviour for the solutions, where the notion of universality refers to asymptotic independence of the structure of solutions (at the point of gradient catastrophe) from the choice of generic initial data as well as from the choice of a generic PDE. KP solitons in shallow water Kodama [3] presents a survey of recent studies on soliton solutions of the Kadomtsev-Petviashvili (KP) equation. A large variety of exact soliton solutions of the KP equation are presented and classified. The study includes numerical analysis of the stability of the found solution as well as numerical simulations of the initial value problems which indicate that a certain class of initial waves approach asymptotically these exact solutions

Gómez-Ullate, David; Lombardo, Sara; Mañas, Manuel; Mazzocco, Marta; Nijhoff, Frank; Sommacal, Matteo

2010-10-01

235

Quenched and annealed disorder in copolymer melts  

NASA Astrophysics Data System (ADS)

We develop models to study the effects of architectural disorder in two types of copolymers: random linear copolymers and random graft copolymers. In both cases, the models include Gaussian chain connectivity, interactions between different monomer types parameterized by the Flory-Huggins parameter, and an incompressibility constraint to simulate a melt. Quenched and annealed disorder is defined in this context. Quenched disorder is generally an accurate description of real polymer systems, where each polymers has a fixed architecture. However an annealed system, where the polymers are allowed to reform themselves, is much more analytically accessible. For linear random copolymers, the difference between quenched and annealed disorder is explored within the weak segregation regime, where the interaction strength is not too great and the system is close to the homogeneous phase. The disorder is described using both correlated and uncorrelated sequence distributions. We then describe how to model the probability distribution for a subset of linear random copolymers, called tapered copolymers, based on the polymerization process. We present numerical mean field solutions to compare the uncorrelated and correlated probability distributions for the tapered copolymers within the annealed approximation. We find that for very correlated sequence distributions, the phase behavior differs greatly between the correlated system and the analogous system without correlations. A general model for randomly grafted copolymers is described, in which the backbone copolymer is composed of a different monomer type than the branches and there can be any number of possible grafting sites along the backbone. We then specialize to the case where there are three possible graft sites per polymer. For this simple model we are able to enumerate all the possible polymer species 23, and directly compare the difference between quenched and annealed disorder in the mean field regime. We find that there is little difference between the quenched and annealed systems in terms of the overall spacial distribution of A and B monomer types, but there is a considerable difference in the distribution of polymer species in the two systems.

Patel, Deena Minu

236

Correlation of structural, chemical, and magnetic properties in annealed Ti/Ni multilayers  

SciTech Connect

Ti/Ni multilayer samples have been synthesized on float glass substrates using an electron-beam evaporation technique under ultrahigh vacuum conditions at room temperature. Grazing incidence x-ray diffraction (GIXRD) and grazing incidence x-ray reflectivity (GIXRR) techniques were used, respectively, to study structural modifications and to determine corresponding changes in microstructural parameters, such as individual layer thickness, interface roughness, and electron density due to annealing treatment. In addition to this, the chemical nature of the surface and interfaces of these samples were also studied using a depth profile x-ray photoelectron spectroscopy (XPS) technique. The GIXRD measurement show clear amorphization of the as-deposited multilayer sample annealed in the temperature range of 300-400 deg. C. The corresponding GIXRR measurement indicates the formation of a sufficiently thick layer of Ti-Ni at interfaces converting the Ti/Ni bilayer into a Ti/Ti-Ni/Ni trilayer multilayer structure. The precipitation of the Ti-Ni alloy phase at the interface in the case of samples annealed at 400 deg. C has been confirmed by XPS measurements. The magnetization behavior investigated using the magneto-optical Kerr effect technique clearly shows well the saturation magnetization behavior for all samples annealed up to 300 deg. C, while the sample annealed at 400 deg. C does not show saturation magnetization. The corresponding coercivity value (H{sub c}) is also found to be changed drastically from 15.5 to 0.6 Oe. This observed magnetization behavior is discussed and correlated with structural and chemical changes in the multilayer structure.

Bhatt, Pramod; Sharma, Anupam; Chaudhari, S.M. [Inter-University Consortium for DAE Facilities, University Campus, Khandwa Road, Indore-452017 (India)

2005-02-15

237

The importance of annealing 316 LVM stents.  

PubMed

The annealing process is an important key step in the manufacture of high quality and reliable 316 LVM stents. [figure: see text] The methods commonly applied for verifying the outcome of the annealing process such as microhardness testing are inappropriate and should not be used. The tension testing of tubes, processed together with stents, provides reliable results of the final material properties of stents. During the course of the investigation the grain size was reduced significantly and the break elongation improved. The surface of the strain-tested material shows substantial improvements. All results are particularly important for thin-wall stents with filigree struts. PMID:12974121

Meyer-Kobbe, C; Hinrichs, B H

2003-01-01

238

Rock melting tool with annealer section  

DOEpatents

A rock melting penetrator is provided with an afterbody that rapidly cools a molten geological structure formed around the melting tip of the penetrator to the glass transition temperature for the surrounding molten glass-like material. An annealing afterbody then cools the glass slowly from the glass transition temperature through the annealing temperature range to form a solid self-supporting glass casing. This allows thermally induced strains to relax by viscous deformations as the molten glass cools and prevents fracturing of the resulting glass liner. The quality of the glass lining is improved, along with its ability to provide a rigid impermeable casing in unstable rock formations.

Bussod, Gilles Y. (Santa Fe, NM); Dick, Aaron J. (Oakland, CA); Cort, George E. (Montrose, CO)

1998-01-01

239

Entrapment Type Vacuum Pumps  

NSDL National Science Digital Library

This is a description for a learning module from Maricopa Advanced Technology Education Center. This PDF describes the module; access may be purchased by visiting the MATEC website. Entrapment type pumps operate primarily in the high to ultra-high vacuum ranges. The discussion in this MATEC module includes applications, theory of operation, operating range and preventative maintenance. The focus is on three major types of pumps: cryosorption, cryogenic and sputter-ion. The overall performance of these types of pumps depends on a variety of parameters. For example, it is important that learners understand the balance between pumping speed and capacity. Competency is demonstrated as the learners specify systems for defined process applications.

240

Control Dewar Secondary Vacuum Container  

SciTech Connect

This engineering note provides background information regarding the control dewar secondary vacuum container. The secondary vacuum container has it's origin with the CDP control dewar design. The name secondary vacuum container replaced the CDP term 'Watt can' which was named after Bob Watt (SLAC), a PAC/DOE review committee member who participated in a review of CDP and recommended a secondary vacuum enclosure. One of the most fragile parts of the control dewar design is the ceramic electrical feed throughs located in the secondary vacuum container. The secondary vacuum container is provided to guard against potential leaks in these ceramic insulating feed throughs. The secondary vacuum container has a pumping line separate from the main solenoid/control dewar insulating vacuum. This pumping line is connected to the inlet of the turbo pump for initial pumpdown. Under normal operation the container is isolated. Should a feedthrough develop a small leak, alternate pumping arrangements for the secondary vacuum container could be arranged. The pressure in the secondary vacuum container should be kept in a range that the breakdown voltage is kept at a maximum. The breakdown voltage is known to be a function of pressure and is described by a Paschen curve. I cannot find a copy of the curve at this time, but from what I remember, the breakdown voltage is a minimum somewhere around 10-3 torr. Ideally the pressure in the secondary vacuum can should be kept very low, around 10 E-6 or 10 E-7 torr for maximum breakdown voltage. If however a leak developed and this was not possible, then one could operate at a pressure higher than the minima point.

Rucinski, R.; /Fermilab

1993-10-04

241

Modeling of a Microscale Short Vacuum Arc for a Space Propulsion Thruster  

Microsoft Academic Search

A model of generation of the plasma supported by the operation of a microscale vacuum arc was developed, considering the phenomena in the cathode and anode spots. The nonequilibrium layers produced by cathode and anode evaporation were studied, and the electrode erosion rates as well as the plasma parameters were calculated. The calculation for 50 A showed that the plasma

Isak I. Beilis

2008-01-01

242

THE EFFECT OF POST-IRRADATION ANNEALING ON STACKING FAULT TETRAHEDRA IN NEUTRON-IRRADIATED OFHC COPPER  

SciTech Connect

Two irradiation experiments have been completed wherein two sets of tensile specimens of OFHC copper were irradiated with fission neutrons, one set at 200 degrees C and the other at 250 degrees C. Post-irradiation annealing in vacuum was then used to evaluate the change in the defect microstructure, including vacancy-type SFT, voids, and dislocation loops. Individual samples within each set were given one annealing exposure at 300, 350, 400, 450, 500, or 550 degrees C for 2 hours. The fine-scale defect microstructure was characterized by transmission electron microscopy (TEM) to compare the defect size and spatial distribution at each annealing temperature and reference the results to that measured in the as-irradiated condition. Based on the change in the SFT size distributions, post-irradiation annealing led to a preferential removal of the smaller sized SFT, but did not lead to a general coarsening as might be expected from an Oswald ripening scenario. The issue of whether the SFT produced during irradiation are all structurally perfect is still being investigated at the time of this report, however, the images of the SFT appeared more perfect after annealing at 300 degrees C and higher. Further analysis is being performed to determine whether intermediate stages of SFT formation exist in the as-irradiated condition.

Edwards, Danny J.; Singh, Bachu N.; Eldrup, M.

2003-09-03

243

Annealing induced changes in ternary nanostructured ZnxCd1-xSe thin films: structure and morphology  

NASA Astrophysics Data System (ADS)

Single layers of ZnxCd1-xSe with various compositions (x = 0.39, 0.59 and 0.8) were prepared by thermal vacuum evaporation at room substrate temperature. Consecutive deposition of small portions of ZnSe and CdSe with equivalent thickness of 0.12 or 0.37 nm was applied. X-ray diffraction and atomic force microscopy measurements were applied to explore the evolution of the crystal structure, microstructure, composition and surface morphology upon furnace annealing at 200 °C and 400 °C in an inert atmosphere. It has been found that as-deposited films were nanocrystalline with a grain size of around 10 nm and cubic structure. Upon annealing the size increased approximately three times and the cubic structure was preserved; no appearance of wurtzite phase was observed. It has been also ascertained that annealing caused significant reduction of the film surface roughness. Atomic force microscopy phase images revealed existence of a second phase on the surface of as-deposited films which disappeared after annealing. The effect of the preparation conditions on the film properties and annealing induced changes is discussed.

Bineva, I.; Nesheva, D.; Pejova, B.; Mineva, M.; Levi, Z.; Aneva, Z.

2012-12-01

244

The microstructural response of mill-annealed and solution-annealed INCONEL 600 to heat treatment  

NASA Astrophysics Data System (ADS)

Samples of INCONEL* 600 were examined in the mill-annealed and solution-annealed states, and after isothermal annealing at 400 °C and 650 °C. The corrosion behavior of the samples was examined, analytical electron microscopy was used to determine the microstructures present and the chemistry of grain boundaries, and Auger electron spectroscopy was used to measure grain boundary segregation. Samples of different alloys in the mill-annealed state were found to have quite different microstructures, with Cr-rich M7C3 carbides occurring either along grain boundaries or in intragranular sheets. The corrosion behavior of the samples correlated well with the occurrence of grain boundary chromium depletion. Solution annealing at 1190 °C caused dissolution of all carbides, whereas at 1100 °C the carbides either dissolved or the grain boundaries moved away from the carbides, depending upon alloy carbon content. Low-temperature annealing at 400 °C had little effect on millannealed or fully solutionized samples, but in samples with intragranular carbides present, the grain boundaries moved until intersecting or adjacent to the carbides. Isothermal annealing at 650 °C caused carbide nucleation and growth at grain boundaries in fully solutionized samples. Chromium depletion at grain boundaries accompanied carbide precipitation, with a minimum chromium level of 6 wt pct achieved after 5 hours. Healing was found to occur after 100 hours. Solution-annealed samples with intragranular carbides present had more rapid corrosion kinetics since the grain boundaries moved back to the existing carbides. Thermodynamic analysis of the chromium-depletion process showed good agreement with experimental measurements. The Auger results found only boron present at grain boundaries in the mill-annealed state. Aged samples had boron, nitrogen, and phosphorus present, with phosphorus and nitrogen segregating to the greatest extent. The kinetics of phosphorus segregation are much slower at 400 °C compared with 650 °C.

Hall, Ernest L.; Briant, Clyde L.

1985-07-01

245

Vacuum Gas Tungsten Arc Welding  

NASA Technical Reports Server (NTRS)

A two-year program investigated vacuum gas tungsten arc welding (VGTAW) as a method to modify or improve the weldability of normally difficult-to-weld materials. After a vacuum chamber and GTAW power supply were modified, several difficult-to-weld materials were studied and key parameters developed. Finally, Incoloy 903 weld overlays were produced without microfissures.

Weeks, J. L.; Todd, D. T.; Wooten, J. R.

1997-01-01

246

Braneworld dynamics with vacuum polarization  

E-print Network

We investigate the cosmological dynamics of a brane Universe when quantum corrections from vacuum polarization are taken into account. New vacuum de Sitter points existing on Randall-Sundrum brane are described. We show also that quantum correction can destroy the DGP de Sitter solution on induced gravity brane.

A. V. Toporensky; P. V. Tretyakov

2005-12-15

247

Vacuum Enhanced Cutaneous Biopsy Instrument  

SciTech Connect

A syringe-like disposable cutaneous biopsy instrument equipped with a tubular blade at its lower end, and designed so that a vacuum is created during use, said vacuum serving to retain undeformed a plug of tissue cut from a patient's skin.

Collins, Joseph

1999-06-25

248

Detecting leaks in vacuum bags  

NASA Technical Reports Server (NTRS)

Small leaks in vacuum bag can be readily detected by eye, using simple chemical reaction: combination of ammonia and acetic acid vapors to produce cloudy white smoke. Technique has been successfully used to test seam integrity and to identify minute pinholes in vacuum bag used in assembly of ceramic-tile heat shield for Space Shuttle Orbiter.

Carlstrom, E. E.

1980-01-01

249

Vacuum flash evaporated polymer composites  

DOEpatents

A method for fabrication of polymer composite layers in a vacuum is disclosed. More specifically, the method of dissolving salts in a monomer solution, vacuum flash evaporating the solution, condensing the flash evaporated solution as a liquid film, and forming the condensed liquid film into a polymer composite layer on a substrate is disclosed.

Affinito, J.D.; Gross, M.E.

1997-10-28

250

On simplicity of vacuum modules  

Microsoft Academic Search

We find necessary and sufficient conditions of irreducibility of vacuum modules over affine Lie algebras and superalgebras. From this we derive conditions of simplicity of minimal W-algebras. Moreover, in the case of the Virasoro and Neveu–Schwarz algebras we obtain explicit formulas for the vacuum determinants.

Maria Gorelik; Victor Kac

2007-01-01

251

Purifying Aluminum by Vacuum Distillation  

NASA Technical Reports Server (NTRS)

Proposed method for purifying aluminum employs one-step vacuum distillation. Raw material for process impure aluminum produced in electrolysis of aluminum ore. Impure metal melted in vacuum. Since aluminum has much higher vapor pressure than other constituents, boils off and condenses on nearby cold surfaces in proportions much greater than those of other constituents.

Du Fresne, E. R.

1985-01-01

252

Statistical mechanics of the vacuum  

E-print Network

The vacuum is full of virtual particles which exist for short moments of time. In this paper we construct a chaotic model of vacuum fluctuations associated with a fundamental entropic field that generates an arrow of time. The dynamics can be physically interpreted in terms of fluctuating virtual momenta. This model leads to a generalized statistical mechanics that distinguishes fundamental constants of nature.

Christian Beck

2011-12-07

253

Vacuum enhanced cutaneous biopsy instrument  

DOEpatents

A syringe-like disposable cutaneous biopsy instrument equipped with a tubular blade at its lower end, and designed so that a vacuum is created during use, said vacuum serving to retain undeformed a plug of tissue cut from a patient's skin.

Collins, Joseph (St. Petersburg, FL)

2000-01-01

254

??????????????????????????????????????????? Vacuum Cooling Process of Lettuce  

Microsoft Academic Search

The aim of this research work is to study the moisture and the temperature variation of lettuce under vacuum cooling processes. The experiment was carried out in a rectangular vacuum chamber having a volume of 0.036 m3. The experimental results showed that the cooling rate at the first stage of running was considerably high. the chamber temperature profile during the

Phanlop Saranyachoet; Naris Pratinthong; Thanit Swasdisevi

255

Vacuum energy as dark matter  

NASA Astrophysics Data System (ADS)

We consider the vacuum energy of massive quantum fields in an expanding universe. We define a conserved renormalized energy-momentum tensor by means of a comoving cutoff regularization. Using exact solutions for de Sitter space-time, we show that in a certain range of mass and renormalization scales there is a contribution to the vacuum energy density that scales as nonrelativistic matter and that such a contribution becomes dominant at late times. By means of the WKB approximation, we find that these results can be extended to arbitrary Robertson-Walker geometries. We study the range of parameters in which the vacuum energy density would be compatible with current limits on dark matter abundance. Finally, by calculating the vacuum energy in a perturbed Robertson-Walker background, we obtain the speed of sound of density perturbations and show that the vacuum energy density contrast can grow on sub-Hubble scales as in standard cold dark matter scenarios.

Albareti, F. D.; Cembranos, J. A. R.; Maroto, A. L.

2014-12-01

256

Ordering Phenomena in Undercooled Alloys  

SciTech Connect

Much of the work performed under this grant was devoted to using modern ideas in kinetics to understand atom movements in metallic alloys far from thermodynamic equilibrium. Kinetics arguments were based explicitly on the vacancy mechanism for atom movements. The emphasis was on how individual atom movements are influenced by the local chemical environment of the moving atom, and how atom movements cause changes in the local chemical environments. The author formulated a kinetic master equation method to treat atom movements on a crystal lattice with a vacancy mechanism. Some of these analyses [3,10,16] are as detailed as any treatment of the statistical kinetics of atom movements in crystalline alloys. Three results came from this work. Chronologically they were (1) A recognition that tracking time dependencies is not necessarily the best way to study kinetic phenomena. If multiple order parameters can be measured in a material, the ''kinetic path'' through the space spanned by these order parameters maybe just as informative about the chemical factors that affect atom movements [2,3,5-7,9-11,14-16,18,19,21,23,24,26,36,37]. (2) Kinetic paths need not follow the steepest gradient of the free energy function (this should be well-known), and for alloys far from equilibrium the free energy function can be almost useless in describing kinetic behavior. This is why the third result surprised me. (3) In cluster approximations with multiple order parameters, saddle points are common features of free energy functions. Interestingly, kinetic processes stall or change time scale when the kinetic path approaches a state at a saddle point in the free energy function, even though these states exist far from thermodynamic equilibrium. The author calls such a state a ''pseudostable'' (falsely stable) state [6,21,26]. I have also studied these phenomena by more ''exact'' Monte Carlo simulations. The kinetic paths showed features similar to those found in analytical theories. The author found that a microstructure with interfaces arranged in space as a periodic minimal surface is a probably an alloy at a saddle point in its free energy function [21,26,37].

Fultz, Brent

1997-07-17

257

Data acquisition and simulation of natural phenomena  

Microsoft Academic Search

Virtual natural phenomena obtained through mathematical-physical modeling and simulation as well as graphics emulation can\\u000a meet the user’s requirements for sensory experiences to a certain extent but they can hardly have the same accurate physical\\u000a consistency as real natural phenomena. The technology for data acquisition and natural phenomena simulation can enable us\\u000a to obtain multi-dimensional and multi-modal data directly from

QinPing Zhao

2011-01-01

258

Deformation and annealing study of Nicraly  

NASA Technical Reports Server (NTRS)

Extensive experiments were carried out on the ODS alloy Nicraly, (an alloy prepared by mechanical alloying and consolidating a powder blend consisting of 16% chromium, 4% aluminum, 2-3% yttria, balance nickel), in efforts to develop methods of controlling the grain size and grain shape of the material. The experiments fell into two general categories: variations in the annealing parameters using the as-extruded material as it was received, and various thermomechanical processing schedules (various combinations of cold work and annealing). Success was achieved in gaining grain size and grain shape control by annealing of the as-extruded material. By proper selection of annealing temperature and cooling rates, the grain size of the as-received material was increased almost two orders of magnitude (from an average grain dimension of 0.023 mm to 1.668 mm) while the aspect ratio was increased by some 50% (from 20:1 to 30:1). No success was achieved in gaining significant control of the grain size and shape of the material by thermo-mechanical processing.

Trela, D. M.; Ebert, L. J.

1975-01-01

259

Drawing graphs nicely using simulated annealing  

Microsoft Academic Search

The paradigm of simulated annealing is applied to the problem of drawing graphs “nicely.” Our algorithm deals with general undirected graphs with straight-line edges, and employs several simple criteria for the aesthetic quality of the result. The algorithm is flexible, in that the relative weights of the criteria can be changed. For graphs of modest size it produces good results,

Ron Davidson; David Harel

1996-01-01

260

Nonepileptic motor phenomena in the neonate  

PubMed Central

The newborn infant is prone to clinical motor phenomena that are not epileptic in nature. These include tremors, jitteriness, various forms of myoclonus and brainstem release phenomena. They are frequently misdiagnosed as seizures, resulting in unnecessary investigations and treatment with anticonvulsants, which have potentially harmful side effects. Unfortunately, there is a paucity of literature about many of these phenomena in the newborn, and some of the major textbooks refer to these events as nonepileptic seizures, leading to further confusion for the practitioner. The present paper aims to review these phenomena with special emphasis on differentiating them from epileptic seizures, and offers information on treatment and prognosis wherever possible. PMID:19436521

Huntsman, Richard James; Lowry, Noel John; Sankaran, Koravangattu

2008-01-01

261

Observation of Celestial Phenomena in Ancient China  

NASA Astrophysics Data System (ADS)

Because of the need for calendar-making and portent astrology, the Chinese were diligent and meticulous observers of celestial phenomena. China has maintained the longest continuous historical records of celestial phenomena in the world. Extraordinary or abnormal celestial events were particularly noted because of their astrological significance. The historical records cover various types of celestial phenomena, which include solar and lunar eclipses, sunspots, "guest stars" (novae or supernovae as we understand today), comets and meteors, and all kinds of planetary phenomena. These records provide valuable historical data for astronomical studies today.

Sun, Xiaochun

262

EDITORIAL: Quantum phenomena in Nanotechnology Quantum phenomena in Nanotechnology  

NASA Astrophysics Data System (ADS)

Twenty years ago the Institute of Physics launched the journal Nanotechnology from its publishing house based in the home town of Paul Dirac, a legendary figure in the development of quantum mechanics at the turn of the last century. At the beginning of the 20th century, the adoption of quantum mechanical descriptions of events transformed the existing deterministic world view. But in many ways it also revolutionised the progress of research itself. For the first time since the 17th century when Francis Bacon established inductive reasoning as the means of advancing science from fact to axiom to law, theory was progressing ahead of experiments instead of providing explanations for observations that had already been made. Dirac's postulation of antimatter through purely theoretical investigation before its observation is the archetypal example of theory leading the way for experiment. The progress of nanotechnology and the development of tools and techniques that enabled the investigation of systems at the nanoscale brought with them many fascinating observations of phenomena that could only be explained through quantum mechanics, first theoretically deduced decades previously. At the nanoscale, quantum confinement effects dominate the electrical and optical properties of systems. They also render new opportunities for manipulating the response of systems. For example, a better understanding of these systems has enabled the rapid development of quantum dots with precisely determined properties, which can be exploited in a range of applications from medical imaging and photovoltaic solar cells to quantum computation, a radically new information technology being currently developed in many labs worldwide. As the first ever academic journal in nanotechnology, {\\it Nanotechnology} has been the forum for papers detailing progress of the science through extremely exciting times. In the early years of the journal, the investigation of electron spin led to the formulation of quantum cellular automata, a new paradigm for computing as reported by Craig S Lent and colleagues (Lent C S, Tougaw P D, Porod W and Bernstein G H 1993 Nanotechnology 4 49-57). The increasingly sophisticated manipulation of spin has been an enduring theme of research throughout this decade, providing a number of interesting developments such as spin pumping (Cota E, Aguado R, Creffield C E and Platero G 2003 Nanotechnology 14 152-6). The idea of spin qubits, proposed by D Loss and D P DiVincenzo (1998 Phys. Rev. A 57 120), developed into an established option for advancing research in quantum computing and continues to drive fruitful avenues of research, such as the integrated superconductive magnetic nanosensor recently devised by researchers in Italy (Granata C, Esposito E, Vettoliere A, Petti L and Russo M 2008 Nanotechnology 19 275501). The device has a spin sensitivity in units of the Bohr magneton of 100 spin Hz-1/2 and has large potential for applications in the measurement of nanoscale magnetization and quantum computing. The advance of science and technology at the nanoscale is inextricably enmeshed with advances in our understanding of quantum effects. As Nanotechnology celebrates its 20th volume, research into fundamental quantum phenomena continues to be an active field of research, providing fertile pasture for developing nanotechnologies.

Loss, Daniel

2009-10-01

263

WESF natural phenomena hazards survey  

SciTech Connect

A team of engineers conducted a systematic natural hazards phenomena (NPH) survey for the 225-B Waste Encapsulation and Storage Facility (WESF). The survey is an assessment of the existing design documentation to serve as the structural design basis for WESF, and the Interim Safety Basis (ISB). The lateral force resisting systems for the 225-B building structures, and the anchorages for the WESF safety related systems were evaluated. The original seismic and other design analyses were technically reviewed. Engineering judgment assessments were made of the probability of NPH survival, including seismic, for the 225-B structures and WESF safety systems. The method for the survey is based on the experience of the investigating engineers,and documented earthquake experience (expected response) data.The survey uses knowledge on NPH performance and engineering experience to determine the WESF strengths for NPH resistance, and uncover possible weak links. The survey, in general, concludes that the 225-B structures and WESF safety systems are designed and constructed commensurate with the current Hanford Site design criteria.

Wagenblast, G.R., Westinghouse Hanford

1996-07-01

264

Monitoring of Transient Lunar Phenomena  

NASA Astrophysics Data System (ADS)

Transient Lunar Phenomena (TLP’s) are described as short-lived changes in the brightness of areas on the face of the Moon. TLP research is characterized by the inability to substantiate, reproduce, and verify findings. Our current research includes the analysis of lunar images taken with two Santa Barbara Instrument Group (SBIG) ST8-E CCD cameras mounted on two 0.36m Celestron telescopes. On one telescope, we are using a sodium filter, and on the other an H-alpha filter, imaging approximately one-third of the lunar surface. We are focusing on two regions: Hyginus and Ina. Ina is of particular interest because it shows evidence of recent activity (Schultz, P., Staid, M., Pieters, C. Nature, Volume 444, Issue 7116, pp. 184-186, 2006). A total of over 50,000 images have been obtained over approximately 35 nights and visually analyzed to search for changes. As of March, 2014, no evidence of TLPs has been found. We are currently developing a Matlab program to do image analysis to detect TLPs that might not be apparent by visual inspection alone.

Barker, Timothy; Farber, Ryan; Ahrendts, Gary

2014-06-01

265

Interference Phenomena in Quantum Information  

E-print Network

One of the key features of quantum mechanics is the interference of probability amplitudes. The reason for the appearance of interference is mathematically very simple. It is the linear structure of the Hilbert space which is used for the description of quantum systems. In terms of physics we usually talk about the superposition principle valid for individual and composed quantum objects. So, while the source of interference is understandable it leads in fact to many counter-intuitive physical phenomena which puzzle physicists for almost hundred years. The present thesis studies interference in two seemingly disjoint fields of physics. However, both have strong links to quantum information processing and hence are related. In the first part we study the intriguing properties of quantum walks. In the second part we analyze a sophisticated application of wave packet dynamics in atoms and molecules for factorization of integers. The main body of the thesis is based on the original contributions listed separately at the end of the thesis. The more technical aspects and brief summaries of used methods are left for appendices.

Martin Stefanak

2010-09-01

266

Avalanche Phenomena in Pore Draining  

NASA Astrophysics Data System (ADS)

Hysteresis curves measured for superfluid ^4He capillary condensation in Nuclepore membrane indicate deviations from the independent element model. Nuclepore is an interesting material to study since every pore threads the membrane from top to bottom, but non-trivial in the sense that pore intersections seem to play an important role in the hysteresis phenomena observed. Especially interesting in the hysteresis is the sharp draining which occurs as the pores first begin to empty. This has been seen in other hysteretic capillary systems.footnote J. H. Page, J. Liu, B. Abeles, H. W. Deckman, and D. A. Weitz, Phys. Rev. Letters 71, 1216 (1993), for example. We have observed the existence of steps, or avalanches(M. P. Lilly, P. T. Finley, and R. B. Hallock, Phys. Rev. Letters 71), 4186 (1993). , as large groups of pores (<~10^7 out of a total sample size of ~ 10^9 pores) empty in the steep, initial portion of the draining curve. By use of spatially separated detectors, we show that avalanches involve macroscopic (rather than just local) regions of the Nuclepore. We report measurements of the size distribution, duration, and spatial extent of the avalanche events.

Lilly, M. P.; Hallock, R. B.

1996-03-01

267

Precursor films in wetting phenomena  

E-print Network

The spontaneous spreading of non-volatile liquid droplets on solid substrates poses a classic problem in the context of wetting phenomena. It is well known that the spreading of a macroscopic droplet is in many cases accompanied by a thin film of macroscopic lateral extent, the so-called precursor film, which emanates from the three-phase contact line region and spreads ahead of the latter with a much higher speed. Such films have been usually associated with liquid-on-solid systems, but in the last decade similar films have been reported to occur in solid-on-solid systems. While the situations in which the thickness of such films is of mesoscopic size are rather well understood, an intriguing and yet to be fully understood aspect is the spreading of microscopic, i.e., molecularly thin films. Here we review the available experimental observations of such films in various liquid-on-solid and solid-on-solid systems, as well as the corresponding theoretical models and studies aimed at understanding their formation and spreading dynamics. Recent developments and perspectives for future research are discussed.

M. N. Popescu; G. Oshanin; S. Dietrich; A. -M. Cazabat

2012-05-07

268

Surface Chemistry, Friction, and Wear Properties of Untreated and Laser-Annealed Surfaces of Pulsed-Laser-Deposited WS(sub 2) Coatings  

NASA Technical Reports Server (NTRS)

An investigation was conducted to examine the surface chemistry, friction, and wear behavior of untreated and annealed tungsten disulfide (WS2) coatings in sliding contact with a 6-mm-diameter 440C stainless-steel ball. The WS2 coatings and annealing were performed using the pulsed-laser-deposition technique. All sliding friction experiments were conducted with a load of 0.98 N (100 g), an average Hertzian contact pressure of 0.44 GPa, and a constant rotating speed of 120 rpm. The sliding velocity ranged from 31 to 107 mm/s because of the range of wear track radii involved in the experiments. The experiment was performed at room temperature in three environments: ultrahigh vacuum (vacuum pressure, 7X(exp -10) Pa), dry nitrogen (relative humidity, less than 1 percent), and humid air (relative humidity, 15 to 40 percent). Analytical techniques, including scanning electron microscopy (SEM), energy-dispersive x-ray spectroscopy (EDX), x-ray photo electron spectroscopy (XPS), surface profilometry, and Vickers hardness testing, were used to characterize the tribological surfaces of WS2 coatings. The results of the investigation indicate that the laser annealing decreased the wear of a WS2 coating in an ultrahigh vacuum. The wear rate was reduced by a factor of 30. Thus, the laser annealing increased the wear life and resistance of the WS2 coating. The annealed WS 2 coating had a low coefficient of friction (less than O.1) and a low wear rate ((10(exp -7) mm(exp 3)/N-m)) both of which are favorable in an ultrahigh vacuum.

Miyoshi, Kazuhisa; Wheeler, Donald R.; Zabinski, Jeffrey S.

1996-01-01

269

Vacuum 80 (2006) 11991205 One-dimensional simulation of multi pulse phenomena in  

E-print Network

is very sensitive to plasma chemistry model. Impurity effects appear to play an important role requires a detailed understanding of the fundamental physical and chemical processes in an APG plasma; Multiple pulse; Plasma modeling 1. Introduction There is rapidly growing interest in atmospheric

Raja, Laxminarayan L.

270

Discharge phenomena associated with a preheated wire explosion in vacuum: Theory and comparison with experiment  

NASA Astrophysics Data System (ADS)

This paper presents the experimental and simulation results of electrical explosions of preheated tungsten wires at a current rise time of several tens of nanoseconds and at a current density of ˜108A/cm2. The electrical characteristics of wire explosion (WE) were measured. The image of a wire during the electrical explosion was obtained with the help of a framing camera. The proposed magnetohydrodynamic (MHD) model takes into account different stages of WE, namely, the wire heating and vaporization, the phase transition, and the shunting discharge. Two different mathematical approaches were used for WE simulation at different stages. At the first stage, the simulation included a code describing the wire state. At the second stage, the shunting discharge was simulated together with the wire state. The simulation code includes the set of MHD equations, the equilibrium equation of state (density and temperature-dependent pressure and specific internal energy), electron transport models (density and temperature-dependent electrical conductivity and thermal conductivity), and electric circuit equations. Thermionic emission and vapor ionization initiate the plasma layer, which develops around the wire core and supports the shunting discharge. The calculated waveforms of the wire voltage and current, as well as the velocity of the expanding plasma, are in a good agreement with the experimental data.

Beilis, I. I.; Baksht, R. B.; Oreshkin, V. I.; Russkikh, A. G.; Chaikovskii, S. A.; Labetskii, A. Yu.; Ratakhin, N. A.; Shishlov, A. V.

2008-01-01

271

Vacuum phenomenon: Clinical relevance.  

PubMed

Vacuum phenomenon (VP) is an anatomical entity of potential confusion in the diagnosis and evaluation of joint pathology. Observation of this phenomenon has been demonstrated on basic radiographs, computed tomography, and magnetic resonance imaging. Although VP is most often associated with degenerative joint disease, it is observed with other pathologies. Two problematic scenarios can occur: a false-positive diagnosis of serious pathology instead of benign VP and a false-negative diagnosis of benign VP with a more serious underlying process Despite this potential for confusion, criteria for distinguishing VP from other causes of joint pain and for evaluating a suspected case of VP have not been fully established. We reviewed the literature to determine underlying mechanism, symptomology, associated pathologies, and clinical importance of VP. The formation of VP can be explained by gas solubility, pressure-volume relationships, and human physiology. CT, GRE-MRI, and multipositional views are the best imaging studies to view VP. Although most cases of VP are benign, it can be associated with clinical signs and symptoms. VP outside the spine is an underreported finding on imaging studies. VP should be on the differential diagnosis for joint pain, especially in the elderly. We have proposed criteria for diagnosing VP and generated a basic algorithm for its workup. Underreporting of this phenomenon shows a lack of awareness of VP on the part of physicians. By identifying true anatomic VP, we can prevent harm from suboptimal treatment of patients. PMID:24288359

Gohil, Ishan; Vilensky, Joel A; Weber, Edward C

2014-04-01

272

Compact vacuum insulation  

DOEpatents

Improved compact insulation panel is provided which is comprised of two adjacent metal sheets spaced close together with a plurality of spherical, or other discretely shaped, glass or ceramic beads optimally positioned between the sheets to provide support and maintain the spacing between the metal sheets when the gases there between are evacuated to form a vacuum. These spherical glass beads provide the maximum support while minimizing thermal conductance. In its preferred embodiment; these two metal sheets are textured with ribs or concave protrusions in conjunction with the glass beads to maximize the structural integrity of the panels while increasing the spacing between beads, thereby reducing the number of beads and the number of thermal conduction paths. Glass or porcelain-enameled liners in combination with the glass spacers and metal sidewalls effectively decrease thermal conductivity, and various laminates, including wood, porcelain-enameled metal, and others effectively increase the strength and insulation capabilities of the panels. Also, a metal web is provided to hold the spacers in place, and strategic grooves are shown to accommodate expansion and contraction or shaping of the panels. 35 figs.

Benson, D.K.; Potter, T.F.

1992-10-27

273

Compact vacuum insulation  

DOEpatents

Improved compact insulation panel is provided which is comprised of two adjacent metal sheets spaced close together with a plurality of spherical, or other discretely shaped, glass or ceramic beads optimally positioned between the sheets to provide support and maintain the spacing between the metal sheets when the gases therebetween are evacuated to form a vacuum. These spherical glass beads provide the maximum support while minimizing thermal conductance. In its preferred embodiment; these two metal sheets are textured with ribs or concave protrusions in conjunction with the glass beads to maximize the structural integrity of the panels while increasing the spacing between beads, thereby reducing the number of beads and the number of thermal conduction paths. Glass or porcelain-enameled liners in combination with the glass spacers and metal sidewalls effectively decrease thermal conductivity, and variious laminates, including wood, porcelain-enameled metal, and others effectively increase the strength and insulation capabilities of the panels. Also, a metal web is provided to hold the spacers in place, and strategic grooves are shown to accommodate expansion and contraction or shaping of the panels.

Benson, David K. (Golden, CO); Potter, Thomas F. (Denver, CO)

1992-01-01

274

Vacuum plasma spray coating  

NASA Technical Reports Server (NTRS)

Currently, protective plasma spray coatings are applied to space shuttle main engine turbine blades of high-performance nickel alloys by an air plasma spray process. Originally, a ceramic coating of yttria-stabilized zirconia (ZrO2.12Y2O3) was applied for thermal protection, but was removed because of severe spalling. In vacuum plasma spray coating, plasma coatings of nickel-chromium-aluminum-yttrium (NiCrAlY) are applied in a reduced atmosphere of argon/helium. These enhanced coatings showed no spalling after 40 MSFC burner rig thermal shock cycles between 927 C (1700 F) and -253 C (-423 F), while current coatings spalled during 5 to 25 test cycles. Subsequently, a process was developed for applying a durable thermal barrier coating of ZrO2.8Y2O3 to the turbine blades of first-stage high-pressure fuel turbopumps utilizing the enhanced NiCrAlY bond-coating process. NiCrAlY bond coating is applied first, with ZrO2.8Y2O3 added sequentially in increasing amounts until a thermal barrier coating is obtained. The enchanced thermal barrier coating has successfully passed 40 burner rig thermal shock cycles.

Holmes, Richard R.; Mckechnie, Timothy N.

1989-01-01

275

Precooler Ring Vacuum System  

SciTech Connect

The precooler vacuum system, as proposed by FNAL, is based on a suitable modification of the existing Electron Cooling Ring System. Because of the magnetic cycle of the bending magnets, distributed ion pumping, as exists in the Electron Cooling Ring, is not applicable. Instead, the proposed pumping will be done with commercial appendage ion pumps mounted approximately every two meters around the circumference of the ring. The loss of effective pumping speed and non-uniformity of system pressure with appendage pumps may not be major considerations but the large number required does effect experimental and analytical equipment placement considerations. There is a distributed pumping technique available which: (1) is not affected by the magnetic cycle of the bending magnets; (2) will provide a minimum of four times the hydrogen pumping speed of the proposed appendage ion pumps; (3) will require no power during pumping after the strip is activated; (4) will provide the heat source for bakeout; (5) is easily replaceable; and (6) can be purchased, installed, and operated at a generous economic advantage over the presently proposed ion pumped system. The pumping technique referred to is non-evaporable gettering with ST101 Zr/Al pumping strip. A technical description of this pumping strip is given on Data Sheet 1 and 2 attached to this report.

Moenich, J.

1980-10-02

276

NCSX Vacuum Vessel Fabrication  

SciTech Connect

The National Compact Stellarator Experiment (NCSX) is being constructed at the Princeton Plasma Physics Laboratory (PPPL) in conjunction with the Oak Ridge National Laboratory (ORNL). The goal of this experiment is to develop a device which has the steady state properties of a traditional stellarator along with the high performance characteristics of a tokamak. A key element of this device is its highly shaped Inconel 625 vacuum vessel. This paper describes the manufacturing of the vessel. The vessel is being fabricated by Major Tool and Machine, Inc. (MTM) in three identical 120º vessel segments, corresponding to the three NCSX field periods, in order to accommodate assembly of the device. The port extensions are welded on, leak checked, cut off within 1" of the vessel surface at MTM and then reattached at PPPL, to accommodate assembly of the close-fitting modular coils that surround the vessel. The 120º vessel segments are formed by welding two 60º segments together. Each 60º segment is fabricated by welding ten press-formed panels together over a collapsible welding fixture which is needed to precisely position the panels. The vessel is joined at assembly by welding via custom machined 8" (20.3 cm) wide spacer "spool pieces." The vessel must have a total leak rate less than 5 X 10-6 t-l/s, magnetic permeability less than 1.02?, and its contours must be within 0.188" (4.76 mm). It is scheduled for completion in January 2006.

Viola, M. E.; Brown, T.; Heitzenroeder, P.; Malinowski, F.; Reiersen, W.; Sutton, L.; Goranson, P.; Nelson, B.; Cole, M.; Manuel, M.; McCorkle, D.

2005-10-07

277

Vacuum energy and cosmological evolution  

E-print Network

An expanding universe is not expected to have a static vacuum energy density. The so-called cosmological constant $\\Lambda$ should be an approximation, certainly a good one for a fraction of a Hubble time, but it is most likely a temporary description of a true dynamical vacuum energy variable that is evolving from the inflationary epoch to the present day. We can compare the evolving vacuum energy with a Casimir device where the parallel plates slowly move apart ("expand"). The total vacuum energy density cannot be measured, only the effect associated to the presence of the plates, and then also their increasing separation with time. In the universe there is a nonvanishing spacetime curvature $R$ as compared to Minkowskian spacetime that is changing with the expansion. The vacuum energy density must change accordingly, and we naturally expect $\\delta\\Lambda\\sim R\\sim H^2$. A class of dynamical vacuum models that trace such rate of change can be constructed. They are compatible with the current cosmological data, and conveniently extended can account for the complete cosmic evolution from the inflationary epoch till the present days. These models are very close to the $\\Lambda$CDM model for the late universe, but very different from it at the early times. Traces of the inherent vacuum dynamics could be detectable in our recent past.

Joan Sola

2014-02-27

278

Vacuum Brazing of Accelerator Components  

NASA Astrophysics Data System (ADS)

Commonly used materials for accelerator components are those which are vacuum compatible and thermally conductive. Stainless steel, aluminum and copper are common among them. Stainless steel is a poor heat conductor and not very common in use where good thermal conductivity is required. Aluminum and copper and their alloys meet the above requirements and are frequently used for the above purpose. The accelerator components made of aluminum and its alloys using welding process have become a common practice now a days. It is mandatory to use copper and its other grades in RF devices required for accelerators. Beam line and Front End components of the accelerators are fabricated from stainless steel and OFHC copper. Fabrication of components made of copper using welding process is very difficult and in most of the cases it is impossible. Fabrication and joining in such cases is possible using brazing process especially under vacuum and inert gas atmosphere. Several accelerator components have been vacuum brazed for Indus projects at Raja Ramanna Centre for Advanced Technology (RRCAT), Indore using vacuum brazing facility available at RRCAT, Indore. This paper presents details regarding development of the above mentioned high value and strategic components/assemblies. It will include basics required for vacuum brazing, details of vacuum brazing facility, joint design, fixturing of the jobs, selection of filler alloys, optimization of brazing parameters so as to obtain high quality brazed joints, brief description of vacuum brazed accelerator components etc.

Singh, Rajvir; Pant, K. K.; Lal, Shankar; Yadav, D. P.; Garg, S. R.; Raghuvanshi, V. K.; Mundra, G.

2012-11-01

279

Annealing kinetics of radiation damage in artificial obsidian glass  

Microsoft Academic Search

Annealing kinetics of fission tracks in artificial obsidian glass (modelled after natural Lipari obsidian) doped with 20 ppm uranium has been studied as a function of annealing time and temperature. The observed annealing characteristics can be best described by a two term exponential function p(t) = P1exp(-alpha1t) + P2exp(-alpha2t with an Arrhenius type temperature dependence of the annealing coefficients alphai,

G. Walder; T. D. Märk

1988-01-01

280

Vacuum Effects in Gravitational Fields: Theory and Detectability  

E-print Network

In this thesis, we investigate quantum vacuum effects in the presence of gravitational fields. After discussing the general theory of vacuum effects in strong fields we apply it to the relevant issue of the interaction of the quantum vacuum with black hole geometries. In particular we consider the long-standing problem of the interpretation of gravitational entropy. After these investigations, we discuss the possible experimental tests of particle creation from the quantum vacuum. This leads us to study acoustic geometries and their way of ``simulating'' gravitational structures, such as horizons and black holes. We study the stability of these structures and the problems related to setting up experimental detection of ``phonon Hawking flux'' from acoustic horizons. This line of research then leads us to propose a new model for explaining the emission of light in the phenomenon of Sonoluminescence, based on the dynamical Casimir effect. This is possibly amenable to experimental investigation. Finally we consider high energy phenomena in the early universe. In particular we discuss inflation and possible alternative frameworks for solving the cosmological puzzles.

S. Liberati

2000-09-14

281

Phenomena resulting from hypergolic contact  

NASA Astrophysics Data System (ADS)

Understanding hypergolic ignition is critical for the safe and successful operation of hypergolic engines. The complex coupling of physical and chemical processes during hypergolic ignition complicates analysis of the event. Presently, hypergolic ignition models cannot simulate liquid contact and mixing or liquid-phase chemical reactions, and rely on experimental results for validation. In some cases, chemical kinetics of hypergolic propellants and fluid dynamics of droplet collisions couple to produce unexpected phenomena. This research investigates contact between droplets and pools of liquid hypergolic propellants under various conditions in order to investigate these liquid-phase reactions and categorize the resulting interaction. During this experiment, 142 drop tests were performed to investigate phenomena associated with hypergolic contact of various propellants. A drop of fuel impacted a semi-ellipsoidal pool of oxidizer at varying impact velocities and impact geometries. The temperature, pressure, ambient atmosphere, and propellant quality were all controlled during the experiment, as these factors have been shown to influence hypergolic ignition delay. Three distinct types of impacts were identified: explosions, bounces, and splashes. The impact type was found to depend on the impact Weber number and impact angle. Splashes occurred above a critical Weber number of 250, regardless of impact angle. Explosions occurred for Weber numbers less than 250, and for impact angles less than seven degrees. If the impact angle was greater than seven degrees then the test resulted in a bounce. Literature related to explosions induced by hypergolic contact was reviewed. Explosions were observed to occur inconsistently, a feature that has never been addressed. Literature related to non-reactive splashing, bouncing, and coalescence was reviewed for insight into the explosion phenomenon. I propose that the dependence of impact angle on the transition between explosion and bounce impacts is partially responsible for the explosion inconsistency in literature. No explosions were observed for the alternative hypergolic propellants tested, which could be due to lower gas production rates or the absence of reactive intermediate species present in certain propellant chemistry. In either case, the fluid dynamics of the impact was consistent, but the chemical kinetics of the propellants were different, and presumably, the two did not couple as strongly. Based on the results, explosions appear to be a mixing driven process caused by the coupling between the fluid dynamics of the impact and the chemical kinetics of the propellants. Upon contact, the fuel drop merges with the oxidizer pool. Liquid-phase neutralization reactions produce enough heat to vaporize propellants, which then accumulate within a gas pocket inside the pool. Exothermic gas-phase reactions result in an explosion originating from within the propellant pool. In addition to investigation of the explosion phenomenon, high-speed videos were taken of the first microseconds of hypergolic contact to observe the liquid-phase chemical reactions in detail. The delay between contact and first gas production was measured to be between 20 and 200 microseconds for monomethylhydrazine and red fuming nitric acid. This delay provides insight into the speed of the liquid-phase chemical reactions, and has helped to calibrate liquid-based ignition models. This research has categorized different interactions resulting from hypergolic contact, and found that the impact Weber number and impact angle were the controlling parameters. I propose that slight changes in the impact angle went unobserved by previous researchers and were partially responsible for the explosion inconsistency in literature. Microsecond scale time delays were measured between contact and gas production and have been used to calibrate previously unknown rate constants of liquid-phase chemical reactions.

Forness, Jordan M.

282

Annealing effects on the characteristics of AuCl3-doped graphene  

NASA Astrophysics Data System (ADS)

Single-layer graphene sheets grown on Cu foils by chemical vapor deposition were transferred on 300 nm SiO2/n-type Si wafers and subsequently doped with 10 mM AuCl3 solution. The doped graphene sheets were annealed at various temperatures (TA) under vacuum below 10-3 Torr for 10 min and characterized by atomic force microscopy, Raman spectroscopy, x-ray photoelectron spectroscopy (XPS), and 4-probe van der Pauw method. The XPS studies show that the compositions of Cl and Au3+ ions in doped graphene sheets increase slightly by annealing at 50 °C, but by further increase of TA above 50 °C, they monotonically decrease and become almost negligible at TA = 500 °C. These XPS results are consistent with the corresponding TA-dependent behaviors of the Raman scattering and the sheet resistance, implying that the doping efficiency is maximized at TA = 50 °C and the Cl and Au3+ ions play a major role in the doping/dedoping processes that are very reversible, different from the case of carbon nanotubes. These results suggest that the annealing temperature is a crucial factor to determine the structural and electrical properties of AuCl3-doped graphene. Possible mechanisms are discussed to explain the doping/dedoping processes of graphene sheets.

Hee Shin, Dong; Min Kim, Jong; Wook Jang, Chan; Hwan Kim, Ju; Kim, Sung; Choi, Suk-Ho

2013-02-01

283

Flash lamp annealing of tungsten surfaces marks a new way to optimized slow positron yields  

NASA Astrophysics Data System (ADS)

Tungsten in the form of a mono-crystalline foil with an optimum thickness of about 2 ?m is often used as a positron moderator in mono-energetic positron beams with 22Na positron sources. The efficiency of such a moderator strongly depends on its prior heat treatment, i.e. an annealing procedure with considerable difficulty at temperatures of about 2000 °C under vacuum conditions. Flash lamp annealing (FLA) has been tested as new method to quickly anneal W foils in order to produce easy manageable, low-cost moderators with a high efficiency. With FLA, just the surface of a W foil is heated above the melting point (3422°C) within 1 to 3 ms, i.e. without melting the whole foil volume. In this way, a surface cleaning is reached connected with a considerable increase in the positron diffusion length. Conventional polycrystalline W foils of 9 ?m ± 25% thickness, heat treated by FLA, were characterized and tested as positron moderators. First promising tests result in a moderator efficiency of ~3*10-4 and clearly demonstrate that FLA is also applicable to tungsten meshes.

Anwand, W.; Johnson, J. M.; Butterling, M.; Wagner, A.; Skorupa, W.; Brauer, G.

2013-06-01

284

Infrared study on annealing effect on conformation of zinc stearate  

Microsoft Academic Search

The molecular conformation and thermal transition behavior of two zinc stearate specimens, unannealed one and annealed one, were compared. The unannealed specimen has one thermal transition at 134°C. Annealing was made by increasing temperature to 150°C and cooling to room temperature slowly. This annealed specimen has an exothermic peak at 103°C, and endothermic shoulders and a peak at 118, 124

Tsutomu Ishioka; Atsushi Kiritani; Takuya Kojima

2007-01-01

285

AUTOMATED MALLEABLE ANNEALING OVENS SLOWLY HEAT AND COOL CASTINGS AS ...  

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

AUTOMATED MALLEABLE ANNEALING OVENS SLOWLY HEAT AND COOL CASTINGS AS THEY MOVE IN BINS ALONG TRACKS IN THE OVEN BOTTOM IN THE MALLEABLE ANNEALING BUILDING. THIS PROCESS TRANSFORMS BRITTLE WHITE IRON CASTINGS INTO SOFTER, STRONGER MALLEABLE IRON. - Stockham Pipe & Fittings Company, Malleable Annealing Building, 4000 Tenth Avenue North, Birmingham, Jefferson County, AL

286

Thermoelectric phenomena via an interacting particle system  

E-print Network

Thermoelectric phenomena via an interacting particle system Christian Maes and Maarten H. van for thermoelectric phenomena in terms of an interacting particle system, a lattice electron gas dynamics, a standard reference is [1]. We present an interacting particle system for the standard thermoelectric

Maes, Christian

287

Psychophysiologic Phenomena in Multiple Personality and Hypnosis  

Microsoft Academic Search

This article demonstrates similarities in psychophysiologic phenomena found in Multiple Personality Disorder (MPD), individuals using hypnosis, and others who did not use hypnosis. The areas discussed are: allergic responses, dermatologic reactions, effects on the autonomic nervous system, seizure disorders, pain control, and healing. Examples from multiple personality cases are paralleled by citations of related phenomena from the hypnosis literature. Some

Bennett G. Braun

1983-01-01

288

Economic Agents and Markets as Emergent Phenomena  

E-print Network

, financial institutions,...) and agents representing various other social and environmental phenomena (eEconomic Agents and Markets as Emergent Phenomena LEIGH TESFATSION Department of Economics, Iowa State University, Ames, Iowa 50011-1070 3 December 2001 ABSTRACT An overview of recent work in agent

Tesfatsion, Leigh

289

Gustatory phenomena after upper dorsal sympathectomy.  

PubMed

In a series of 100 bilateral upper dorsal sympathectomies performed for palmar hyperhidrosis, gustatory sweating and other gustatory phenomena were reported by 68 of 93 patients (73%), followed up for an average of 1 1/2 years. These gustatory phenomena were quite different from physiologic gustatory sweating: a wide range of gustatory stimuli caused a variety of phenomena in varied locations. There was a negative correlation between the incidence of these phenomena and the occurrence of Horner's syndrome after sympathectomy. Analysis of our observations, and of clinical and experimental work of others, leads to the conclusion that gustatory phenomena after upper dorsal sympathectomy are the result of preganglionic sympathetic regeneration or collateral sprouting with aberrant synapses in the superior cervical ganglion. PMID:907534

Kurchin, A; Adar, R; Zweig, A; Mozes, M

1977-10-01

290

Understanding the Physics of changing mass phenomena  

NASA Astrophysics Data System (ADS)

Changing mass phenomena, like a falling chain or a bungee jumper, might give surprising results, even for experienced physicists. They have resulted in hot discussions in journals, in which for instance Physics professors claim the impossibility of an acceleration larger then g in case of a bungee jumper. These phenomena are also interesting as topics for challenging student projects, and used as such by Dutch high school students. I will take these phenomena as the context in which I like to demonstrate the possibilities of ICT in the learning process of physics. Especially dynamical modeling enables us to describe these phenomena in an elegant way and with knowledge of high school mathematics. Furthermore tools for video-analysis and data from measurements with sensors allow us to study the phenomena in experiments. This example demonstrates the level of implementation of ICT in Physics Education in The Netherlands [1].

Ellermeijer, A. L.

2008-05-01

291

Conductivity changes in zinc oxide and magnesium zinc oxide nanoparticle films annealed in hydrogen ambient  

NASA Astrophysics Data System (ADS)

This dissertation explores the physics of how the electrical properties of ZnO and MgZnO nanoparticle films are modified when exposed to hydrogen gas at high temperatures. Specifically, with the goal of quantifying the ease of incorporation of the hydrogen atom and its properties as a donor. The nanoparticles were grown on insulating silicon substrates and had an average diameter of 40 nm. The devices were of a two terminal design, where the terminals consisted of two 25 mum diameter gold wires laid parallel to each other on the nanoparticle film to measure the current passing through the film. For the first set of experiments when nanoparticles were exposed to H 2 gas at room temperature, no significant changes in the current-voltage behavior of the nanoparticles were observed relative to measurements done in vacuum. Annealing in H2 below 370K resulted in no significant change in the current. Both the ZnO and MgZnO nanoparticle films showed significant changes at about the same threshold temperatures when annealed to 400K. A second set of experiments were carried out in temperatures up to 500K following the same procedure that showed similar but more complex behavior. The formation energy of hydrogen incorporation was calculated by analysis of the solubility of hydrogen in ZnO at various temperatures. Donor energy level of the nanoparticle films was also calculated by analyzing the post-doping conductivity in vacuum as a function of temperature. The origin of the change in I-V characteristics of ZnO and MgZnO nanoparticles when annealed in H2 ambient, the reasons for the differences of hydrogen doping results between nanoscale and bulk, and the mechanism of hydrogen behavior in the nanoparticle films will be discussed in detail.

Chava, Sirisha

292

Einstein-?tsuki vacuum equations  

NASA Astrophysics Data System (ADS)

The generalisation of the Einstein vacuum theory to ?tsuki geometry is considered. It is shown that the theory based on Lagrangian density ?-gR is consistent and leads to a theory that is classically indistinguishable from the Einstein theory.

Smrz, P. K.

1993-01-01

293

Inhomogeneous and Interacting Vacuum Energy  

NASA Astrophysics Data System (ADS)

Vacuum energy is a simple model for dark energy driving an accelerated expansion of the universe. If the vacuum energy is inhomogeneous in spacetime then it must be interacting. We present the general equations for a spacetime-dependent vacuum energy in cosmology, including inhomogeneous perturbations. We show how any dark energy cosmology can be described by an interacting vacuum+matter. Different models for the interaction can lead to different behaviour (e.g., sound speed for dark energy perturbations) and hence could be distinguished by cosmological observations. As an example we present the cosmic microwave microwave background anisotropies and the matter power spectrum for two different versions of a generalised Chaplygin gas cosmology.

De-Santiago, Josue; Wands, David; Wang, Yuting

294

Vacuum lamination of photovoltaic modules  

NASA Technical Reports Server (NTRS)

Vacuum lamination of terrestrial photovoltaic modules is a new high volume process requiring new equipment and newly develop materials. Equipment development, materials research, and some research in related fields and testing methods are discussed.

Burger, D. R.

1982-01-01

295

Vacuum system pump down analysis  

SciTech Connect

My assignment on the SP-100 Vacuum Vessel Vacuum System Team was to perform a transient pump down analysis for the vacuum vessel that will house the SP-100 reactor during testing. Pump down time was calculated for air and helium. For all cases the proposed vacuum system will be able to pump down the vessel within the required time. The use of a larger rotary piston pump (DUO250) improves the pump down time by 35 minutes and therefore should be considered. The 6-inch duct for the roughing line is optimal, however, because all cases are well below the 24 hour time frame, the 4-inch duct is sufficient. The use of the single turbomolecular pump during pump down is sufficient. A pump down with helium in the vessel and a helium inleakage delays the time to achieve the base pressure marginally and is acceptable.

Rohrdanz, D.R.

1990-08-01

296

Vacuum Variable Medium Temperature Blackbody  

Microsoft Academic Search

This article describes the vacuum variable medium-temperature blackbody (VMTBB) constructed to serve as a highly stable reference\\u000a source with an aperture diameter of 20 mm in the temperature range from 150 °C to 430 °C under medium-vacuum conditions (10?3 Pa) and in a reduced background environment (liquid-nitrogen-cooled shroud). The VMTBB was realized for the calibration facility\\u000a at the PTB in the field of

S. P. Morozova; N. A. Parfentiev; B. E. Lisiansky; U. A. Melenevsky; B. Gutschwager; C. Monte; J. Hollandt

2010-01-01

297

Annealing Vs. Invasion in Phage ? Recombination  

PubMed Central

Genetic recombination catalyzed by ?'s Red pathway was studied in rec(+) and recA mutant bacteria by examining both intracellular ? DNA and mature progeny particles. Recombination of nonreplicating phage chromosomes was induced by double-strand breaks delivered at unique sites in vivo. In rec(+) cells, cutting only one chromosome gave nearly maximal stimulation of recombination; the recombinants formed contained relatively short hybrid regions, suggesting strand invasion. In contrast, in recA mutant cells, cutting the two parental chromosomes at non-allelic sites was required for maximal stimulation; the recombinants formed tended to be hybrid over the entire region between the two cuts, implying strand annealing. We conclude that, in the absence of RecA and the presence of non-allelic DNA ends, the Red pathway of ? catalyzes recombination primarily by annealing. PMID:9383045

Stahl, M. M.; Thomason, L.; Poteete, A. R.; Tarkowski, T.; Kuzminov, A.; Stahl, F. W.

1997-01-01

298

Shock, Post-Shock Annealing, and Post-Annealing Shock in Ureilites  

NASA Technical Reports Server (NTRS)

The thermal and shock histories of ureilites can be divided into four periods: 1) formation, 2) initial shock, 3) post-shock annealing, and 4) post-annealing shock. Period 1 occurred approx.4.55 Ga ago when ureilites formed by melting chondritic material. Impact events during period 2 caused silicate darkening, undulose to mosaic extinction in olivines, and the formation of diamond, lonsdaleite, and chaoite from indigenous carbonaceous material. Alkali-rich fine-grained silicates may have been introduced by impact injection into ureilites during this period. About 57% of the ureilites were unchanged after period 2. During period 3 events, impact-induced annealing caused previously mosaicized olivine grains to become aggregates of small unstrained crystals. Some ureilites experienced reduction as FeO at the edges of olivine grains reacted with C from the matrix. Annealing may also be responsible for coarsening of graphite in a few ureilites, forming euhedral-appearing, idioblastic crystals. Orthopyroxene in Meteorite Hills (MET) 78008 may have formed from pigeonite by annealing during this period. The Rb-Sr internal isochron age of approx.4.0 Ga for MET 78008 probably dates the annealing event. At this late date, impacts are the only viable heat source. About 36% of ureilites experienced period 3 events, but remained unchanged afterwards. During period 4, approx.7% of the ureilites were shocked again, as is evident in the polymict breccia, Elephant Moraine (EET) 83309. This rock contains annealed mosaicized olivine aggregates composed of small individual olivine crystals that exhibit undulose extinction. Ureilites may have formed by impact-melting chondritic material on a primitive body with heterogeneous O isotopes. Plagioclase was preferentially lost from the system due to its low impedance to shock compression. Brief melting and rapid burial minimized the escape of planetary-type noble gases from the ureilitic melts. Incomplete separation of metal from silicates during impact melting left ureilites with relatively high concentrations of trace siderophile elements.

Rubin, Alan E.

2006-01-01

299

Annealing of Solar Cells and Other Thin Film Devices  

NASA Technical Reports Server (NTRS)

Annealing is a key step in most semiconductor fabrication processes, especially for thin films where annealing enhances performance by healing defects and increasing grain sizes. We have employed a new annealing oven for the annealing of CdTe-based solar cells and have been using this system in an attempt to grow US on top of CdTe by annealing in the presence of H2S gas. Preliminary results of this process on CdTe solar cells and other thin-film devices will be presented.

Escobar, Hector; Kuhlman, Franz; Dils, D. W.; Lush, G. B.; Mackey, Willie R. (Technical Monitor)

2001-01-01

300

An in-vacuum diffractometer for resonant elastic soft x-ray scattering.  

PubMed

We describe the design, construction, and performance of a 4-circle in-vacuum diffractometer for resonant elastic soft x-ray scattering. The diffractometer, installed on the resonant elastic and inelastic x-ray scattering beamline at the Canadian Light Source, includes 9 in-vacuum motions driven by in-vacuum stepper motors and operates in ultra-high vacuum at base pressure of 2 × 10(-10) Torr. Cooling to a base temperature of 18 K is provided with a closed-cycle cryostat. The diffractometer includes a choice of 3 photon detectors: a photodiode, a channeltron, and a 2D sensitive channelplate detector. Along with variable slit and filter options, these detectors are suitable for studying a wide range of phenomena having both weak and strong diffraction signals. Example measurements of diffraction and reflectivity in Nd-doped (La,Sr)(2)CuO(4) and thin film (Ga,Mn)As are shown. PMID:21806169

Hawthorn, D G; He, F; Venema, L; Davis, H; Achkar, A J; Zhang, J; Sutarto, R; Wadati, H; Radi, A; Wilson, T; Wright, G; Shen, K M; Geck, J; Zhang, H; Novák, V; Sawatzky, G A

2011-07-01

301

An In-vacuum Diffractometer for Resonant elastic Soft X-ray Scattering  

SciTech Connect

We describe the design, construction, and performance of a 4-circle in-vacuum diffractometer for resonant elastic soft x-ray scattering. The diffractometer, installed on the resonant elastic and inelastic x-ray scattering beamline at the Canadian Light Source, includes 9 in-vacuum motions driven by in-vacuum stepper motors and operates in ultra-high vacuum at base pressure of 2 x 10{sup -10} Torr. Cooling to a base temperature of 18 K is provided with a closed-cycle cryostat. The diffractometer includes a choice of 3 photon detectors: a photodiode, a channeltron, and a 2D sensitive channelplate detector. Along with variable slit and filter options, these detectors are suitable for studying a wide range of phenomena having both weak and strong diffraction signals. Example measurements of diffraction and reflectivity in Nd-doped (La,Sr){sub 2}CuO{sub 4} and thin film (Ga,Mn)As are shown.

D Hawthorn; F He; L Venema; H Davis; A Achkar; J Zhang; R Sutarto; H Wadati; A Radi; et al.

2011-12-31

302

Ex situ elaborated proximity mesoscopic structures for ultrahigh vacuum scanning tunneling spectroscopy  

SciTech Connect

We apply ultrahigh vacuum Scanning Tunneling Spectroscopy (STS) at ultra-low temperature to study proximity phenomena in metallic Cu in contact with superconducting Nb. In order to solve the problem of Cu-surface contamination, Cu(50?nm)/Nb(100?nm) structures are grown by respecting the inverted order of layers on SiO{sub 2}/Si substrate. Once transferred into vacuum, the samples are cleaved at the structure-substrate interface. As a result, a contamination-free Cu-surface is exposed in vacuum. It enables high-resolution STS of superconducting correlations induced by proximity from the underlying superconducting Nb layer. By applying magnetic field, we generate unusual proximity-induced superconducting vortices and map them with a high spatial and energy resolution. The suggested method opens a way to access local electronic properties of complex electronic mesoscopic devices by performing ex situ STS under ultrahigh vacuum.

Stolyarov, V. S. [UMR 7588, Institut des Nanosciences de Paris, UPMC Univ Paris 06, Sorbonne Universités, F-75005 Paris (France); CNRS, UMR 7588, Institut des Nanosciences de Paris, F-75005 Paris (France); Institute of Solid State Physics RAS, 142432 Chernogolovka (Russian Federation); Moscow Institute of Physics and Technology, 141700 Dolgoprudny (Russian Federation); Kazan Federal University, 420008 Kazan (Russian Federation); Moscow State University, 119991 Moscow (Russian Federation); Cren, T., E-mail: tristan.cren@upmc.fr; Debontridder, F.; Brun, C. [UMR 7588, Institut des Nanosciences de Paris, UPMC Univ Paris 06, Sorbonne Universités, F-75005 Paris (France); CNRS, UMR 7588, Institut des Nanosciences de Paris, F-75005 Paris (France); Veshchunov, I. S. [Université de Bordeaux, LP2N, 351 cours de la Libération, F-33405 Talence (France); Institute of Solid State Physics RAS, 142432 Chernogolovka (Russian Federation); Skryabina, O. V. [Institute of Solid State Physics RAS, 142432 Chernogolovka (Russian Federation); Rusanov, A. Yu. [LLC “Applied radiophysics” 142432 Chernogolovka (Russian Federation); Roditchev, D. [UMR 7588, Institut des Nanosciences de Paris, UPMC Univ Paris 06, Sorbonne Universités, F-75005 Paris (France); CNRS, UMR 7588, Institut des Nanosciences de Paris, F-75005 Paris (France); LPEM-UMR 8213, CNRS, ESPCI-ParisTech, UPMC, 10 rue Vauquelin, F-75005 Paris (France)

2014-04-28

303

Vacuum Refining of Molten Silicon  

NASA Astrophysics Data System (ADS)

Metallurgical fundamentals for vacuum refining of molten silicon and the behavior of different impurities in this process are studied. A novel mass transfer model for the removal of volatile impurities from silicon in vacuum induction refining is developed. The boundary conditions for vacuum refining system—the equilibrium partial pressures of the dissolved elements and their actual partial pressures under vacuum—are determined through thermodynamic and kinetic approaches. It is indicated that the vacuum removal kinetics of the impurities is different, and it is controlled by one, two, or all the three subsequent reaction mechanisms—mass transfer in a melt boundary layer, chemical evaporation on the melt surface, and mass transfer in the gas phase. Vacuum refining experimental results of this study and literature data are used to study the model validation. The model provides reliable results and shows correlation with the experimental data for many volatile elements. Kinetics of phosphorus removal, which is an important impurity in the production of solar grade silicon, is properly predicted by the model, and it is observed that phosphorus elimination from silicon is significantly increased with increasing process temperature.

Safarian, Jafar; Tangstad, Merete

2012-12-01

304

Durability of simulated DWPF annealed glasses  

SciTech Connect

Simulated high-level waste glass samples of the DWPF projected compositions were annealed at various times and temperatures in order to develop time-temperature-transformation diagrams. These heat treated glasses were subjected to the Product Consistency Test (PCT) to evaluate glass durability. The B, Li, and Na concentrations in the leachate (the PCT results) were compared to the PCT results of the Environmental Assessment benchmark glass. Durability as a function of glass composition and crystallinity was also examined.

Andrews, M.K.; Cicero, C.A.; Marra, S.L.; Beam, D.C.

1993-03-01

305

Durability of simulated DWPF annealed glasses  

SciTech Connect

Simulated high-level waste glass samples of the DWPF projected compositions were annealed at various times and temperatures in order to develop time-temperature-transformation diagrams. These heat treated glasses were subjected to the Product Consistency Test (PCT) to evaluate glass durability. The B, Li, and Na concentrations in the leachate (the PCT results) were compared to the PCT results of the Environmental Assessment benchmark glass. Durability as a function of glass composition and crystallinity was also examined.

Andrews, M.K.; Cicero, C.A.; Marra, S.L.; Beam, D.C.

1993-01-01

306

Faceted fracture in beta annealed titanium alloys  

Microsoft Academic Search

To better understand the correlation between fatigue failure and prior ?-grain size, in ?-annealed microstructures, the morphology\\u000a of fatigue fracture facets which contain more than one ? platelet colony in Ti-11 and IMI-685 titanium alloys was investigated.\\u000a It was found that most ?\\/? traces on the basal fracture facets, intersect at angles approximately 50, 60 and 70 deg. These\\u000a angles

D. Eylon

1979-01-01

307

Using Simulated Annealing to Factor Numbers  

E-print Network

Almost all public secure communication relies on the inability to factor large numbers. There is no known analytic or classical numeric method to rapidly factor large numbers. Shor[1] has shown that a quantum computer can factor numbers in polynomial time but there is no practical quantum computer that can yet do such computations. We show that a simulated annealing[2] approach can be adapted to find factors of large numbers.

Eric Lewin Altschuler; Timothy J. Williams

2014-02-14

308

Influence of annealing atmosphere on the magnetic properties of SiO{sub 2}/Fe/SiO{sub 2} sandwiched nanocomposite films  

SciTech Connect

The magnetic properties of SiO{sub 2}/Fe/SiO{sub 2} nanocomposite films are studied by magnetic force microscopy and vibrating sample magnetometer. The films were fabricated by alternately depositing SiO{sub 2}, Fe, and SiO{sub 2} on Si substrates with magnetron sputtering followed by thermal annealing. It is found that the annealing atmosphere significantly influences the sample structure, composition, and magnetic properties. The samples annealed in forming gas show much better magnetic properties than those annealed in vacuum and in N{sub 2}. The saturation magnetization can reach 200 emu/g, fairly close to the value of bulk Fe, and the coercivity can reach 400 Oe, much higher than 10 Oe of the bulk Fe. X-ray photoelectron spectroscopic depth profile measurement was carried out to study the mechanism of the strong influence of annealing atmosphere. For the samples annealed in forming gas, Fe nanoparticles are mildly oxidized, forming thin shells of Fe{sub 2}O{sub 3} surrounding them, which is beneficial for maintaining the ferromagnetic behavior and enhancing the coercivity of nanoparticles.

Zhu, P. L.; Liu, Z.; Fan, Y. L.; Jiang, Z. M.; Yang, X. J. [Surface Physics Laboratory (National Key Laboratory), Fudan University, Shanghai 200433 (China); Xue, F. [Analysis and Testing Center, Baosteel Research Institute, Baoshan Iron and Steel Co., Ltd., Shanghai 201900 (China)

2009-08-15

309

Application of laser annealing to solar cell junction formation  

NASA Technical Reports Server (NTRS)

The possibility of using high-energy Q-switched Nd:glass lasers to form pn junctions in solar cells by annealing ion-implanted substrates is investigated. The properties of laser annealed cells are analyzed by electrical, transmission electron microscopy, Rutherford backscattering and secondary ion mass spectrometry techniques. Tests indicate the laser annealed substrates to be damage-free and electrically active. Similar reference analysis of ion-implanted furnace-annealed substrates reveals the presence of residual defects in the form of dislocation lines and loops with substantial impurity redistribution evident for some anneal temperature/time regimes. Fabricated laser annealed cells exhibit excellent conversion efficiency. It is noted that additional improvements are anticipated once the anneal parameters for a back surface field are optimized.

Katzeff, J. S.; Lopez, M.; Josephs, R. H.

1981-01-01

310

Ion-implanted laser annealed silicon solar cells  

NASA Technical Reports Server (NTRS)

Development of low cost solar cells fabrication technology is being sponsored by NASA JPL as part of the Low Cost Solar Array Project (LSA). In conformance to Project requirements ion implantation and laser annealing were evaluated as junction formation techniques offering low cost-high throughput potential. Properties of cells fabricated utilizing this technology were analyzed by electrical, transmission electron microscopy, Rutherford backscattering and secondary ion mass spectrometry techniques. Tests indicated the laser annealed substrates to be damage free and electrically active. Similar analysis of ion implanted furnace annealed substrates revealed the presence of residual defects in the form of dislocation lines and loops with substantial impurity redistribution evident for some anneal temperature/time regimes. Fabricated laser annealed cells exhibited improved spectral response and conversion efficiency in comparison to furnace annealed cells. An economic projection for LSA indicates a potential for considerable savings from laser annealing technology.

Katzeff, J. S.

1980-01-01

311

Exchange enhancement and thermal anneal in Mn{sub 76}Ir{sub 24} bottom-pinned spin valves  

SciTech Connect

Exchange enhancement through thermal anneal in bottom-pinned Mn{sub 76}Ir{sub 24} spin valves is investigated. Samples were fabricated by ion beam deposition (IBD), post-annealed in vacuum (10{sup {minus}6}Torr) at 270{degree}C for 10 min, then cooled in a 3 kOe applied field. For a bilayer structure, glass/Ta 40 Aa/NiFe 30 Aa/MnIr 60 Aa/CoFe 25 Aa/Ta 40 Aa, the exchange field (H{sub ex}) reaches 1148 Oe (J{sub ex}=0.4erg/cm{sup 2}) after anneal. X-ray diffraction (XRD) analysis shows strong enhancement of {l_angle}111{r_angle} texture upon anneal, while grain size obtained from XRD and transmission electron microscopy for as-deposited and annealed states shows no major change. With increasing MnIr thickness, the exchange field decreases, and blocking temperature (T{sub b}) increases, reaching 295{degree}C for t{sub MnIr}=180Aa. Spin valves built with the same exchange bilayer (Ta 20 Aa/NiFe 30 Aa/MnIr 60 Aa/CoFe 25 Aa/Cu 22 Aa/CoFe 20 Aa/NiFe 40 Aa/Ta 40 Aa) show H{sub ex}=855Oe (J{sub ex}=0.3erg/cm{sup 2}) and magnetoresistance (MR)=7.1%. The incorporation of nano-oxide layers in spin valves increases the MR signal to 11%. No signal degradation is found in these specular structures for anneals up to 310{degree}C. {copyright} 2001 American Institute of Physics.

Li, Haohua; Freitas, P. P.; Wang, Zhenjun; Sousa, J. B.; Gogol, P.; Chapman, J.

2001-06-01

312

Structural and electrical characteristics of Ga2O3(Gd2O3)/GaAs under high temperature annealing  

NASA Astrophysics Data System (ADS)

Atomically smooth Ga2O3(Gd2O3)/GaAs interface with low interfacial density of states and low electrical leakage currents have been achieved after the heterostructures were air exposed and tailor annealed to ˜750°C. The heat treatments, with annealing at an intermediate temperature of ˜300°C as a necessary step, were carried out under ultrahigh vacuum (UHV) and via standard rapid thermal annealing with flow of pure nitrogen gas. Furthermore, the oxide remains amorphous and minimal interfacial reaction occurred between the oxide and substrate, critical aspects for device performance. Studies using x-ray reflectivity and high-resolution transmission electron microscopy show that the interfacial roughness is <0.2 and <0.4nm for annealing under UHV and non-UHV, respectively. Electrical measurements on the metal-oxide-semiconductor diodes have exhibited low leakage currents (10-8-10-9A/cm2), a dielectric constant of ?14, and a low interfacial density of states (Dit) of <1012cm-2eV-1.

Chen, C. P.; Lee, Y. J.; Chang, Y. C.; Yang, Z. K.; Hong, M.; Kwo, J.; Lee, H. Y.; Lay, T. S.

2006-11-01

313

Thermal annealing dependence of high-frequency magnetoimpedance in amorphous and nanocrystalline FeSiBCuNb ribbons.  

PubMed

The magnetoimpedance (MI) effect in Fe73.5Si13.5B9Nb3Cu1 melt-spun amorphous ribbons has been studied in the frequency range (1-500 MHz). Isothermal heating treatments in a furnace have been employed to nanocrystallize the ribbons (1 h at 565 degrees C in a vacuum of 10(-3) mbar), while other samples were annealed at lower temperatures (400 and 475 degrees C during 1 h), in order to evaluate the influence of the annealing temperature on the MI effect. The high-frequency impedance was measured using a technique based on the reflection coefficient measurements of a specific transmission line by using a network analyzer. Frequency dependence of the MI ratio, DeltaZ/Z, and both resistive, DeltaR/R, and reactive, DeltaX/X, components of magnetoimpedance were measured in the amorphous and annealed states, at different temperatures. A maximum value of the MI ratio of about 50% at a driving frequency of 18 MHz is obtained in the nanocrystalline (annealed at 565 degrees C) ribbon. Maxima for DeltaR/R of about 81% at 85 MHz and DeltaX/X around 140% at 5 MHz were also achieved. It is revealed that the microstructural evolution in the nanocrystalline sample leads to a magnetic softening, an optimum domain structure and a permeability which is sensitive to frequency and applied magnetic field, generating a large MI response. PMID:18681021

Hernando, B; Prida, V M; Sanchez, M L; Olivera, J; Garcia, C; Santos, J D; Alvarez, P; Sánchez, J L Ll; Perov, N

2008-06-01

314

Effects of electrostatic correlations on electrokinetic phenomena  

E-print Network

The classical theory of electrokinetic phenomena is based on the mean-field approximation that the electric field acting on an individual ion is self-consistently determined by the local mean charge density. This paper ...

Storey, Brian D.

315

Bayesian nonparametric learning of complex dynamical phenomena  

E-print Network

The complexity of many dynamical phenomena precludes the use of linear models for which exact analytic techniques are available. However, inference on standard nonlinear models quickly becomes intractable. In some cases, ...

Fox, Emily Beth

2009-01-01

316

Canister storage building natural phenomena design loads  

SciTech Connect

This document presents natural phenomena hazard (NPH) loads for use in the design and construction of the Canister Storage Building (CSB), which will be located in the 200 East Area of the Hanford Site.

Tallman, A.M.

1996-02-01

317

Reproductive phenomena of a sexual buffelgrass plant  

E-print Network

REPRODUCTIVE PHENOMENA OF A SEXUAL EUFFELGRASS PLANT A Thesis 3y Charles Millard Taliaferro . Submitted to the Graduate School of the A & M University of Texas in partial fulfillment of the requirements for the degree of MASTER OF SCIENCE... January 1964 Major Sub?'ect Agronomy REPRODUCTIVE PHENOMENA OF A SEXUAL BUFFELGRASS PLANT A Thesis Charles Millard Taliaferro Approved as to style and content by: (Chairman of Committee) (Head of Department) / ember) (Member) Memb er) January...

Taliaferro, Charles Millard

1965-01-01

318

Measurement of partial pressures in vacuum technology and vacuum physics  

NASA Technical Reports Server (NTRS)

It is pointed out that the measurement of gaseous pressures of less than 0.0001 torr is based on the ionization of gas atoms and molecules due to collisions with electrons. The particle density is determined in place of the pressure. The ionization cross sections for molecules of various gases are discussed. It is found that the true pressure in a vacuum system cannot be determined with certainty if it is unknown which gas is present. Effects of partial pressure determination on the condition of the vacuum system are discussed together with ion sources, systems of separation, and ion detection.

Huber, W. K.

1986-01-01

319

Vacuum as a hyperbolic metamaterial  

E-print Network

As demonstrated by Chernodub, vacuum in a strong magnetic field behaves as a periodic Abrikosov vortex lattice in a type-II superconductor. We investigate electromagnetic behavior of vacuum in this state. Since superconductivity is realized along the axis of magnetic field only, strong anisotropy of the vacuum dielectric tensor is observed. The diagonal components of the tensor are positive in the x and y directions perpendicular to the magnetic field, and negative in the z direction along the field. As a result, vacuum behaves as a hyperbolic metamaterial medium. If the magnetic field is constant, low frequency extraordinary photons experience this medium as a (3+1) Minkowski spacetime in which the role of time is played by the spatial z coordinate. Spatial variations of the magnetic field curve this effective spacetime, and may lead to formation of "event horizons", which are analogous to electromagnetic black holes in hyperbolic metamaterials. We also note that hyperbolic metamaterials behave as diffractionless "perfect lenses". Since large enough magnetic fields probably had arisen in the course of evolution of early Universe, the demonstrated hyperbolic behavior of early vacuum may have imprints in the large scale structure of the present-day Universe.

Igor I. Smolyaninov

2011-08-10

320

The Light-Front Vacuum  

E-print Network

Background: The vacuum in the light-front representation of quantum field theory is trivial while vacuum in the equivalent canonical representation of the same theory is non-trivial. Purpose: Understand the relation between the vacuum in light-front and canonical representations of quantum field theory and the role of zero-modes in this relation. Method: Vacuua are defined as linear functionals on an algebra of field operators. The role of the algebra in the definition of the vacuum is exploited to understand this relation. Results: The vacuum functional can be extended from the light-front Fock algebra to an algebra of local observables. The extension to the algebra of local observables is responsible for the inequivalence. The extension defines a unitary mapping between the physical representation of the local algebra and a sub-algebra of the light-front Fock algebra. Conclusion: There is a unitary mapping from the physical representation of the algebra of local observables to a sub-algebra of the light-fro...

Herrmann, Marc

2015-01-01

321

Heterogeneous nuclear ribonucleoprotein A1 catalyzes RNA.RNA annealing.  

PubMed

Within the nucleus, pre-mRNA molecules are complexed with a set of proteins to form heterogeneous nuclear ribonucleoprotein complexes. A1, an abundant RNA binding protein present in these complexes, has been shown to bind selectively to single-stranded RNAs and destabilize base-pairing interactions. In this study.A1 is shown to promote the rate of annealing of complementary RNA strands greater than 300-fold under a wide range of salt concentration and temperature. Maximal annealing is observed under saturating or near saturating concentrations of protein, but annealing decreases sharply at both higher and lower concentrations of A1. Kinetic analysis shows that the rate of annealing is not strictly first or second order with respect to RNA at a ratio of protein/RNA that gives optimal rates of annealing. This result suggests that A1 protein may affect more than one step in the annealing reaction. Two polypeptides representing different domains of A1 were also examined for annealing activity. UP1, a proteolytic fragment that represents the N-terminal two-thirds of A1, displays very limited annealing activity. In contrast, a peptide consisting of 48 amino acid residues from the glycine-rich C-terminal region promotes annealing at a rate almost one-quarter that observed with intact A1. The RNA.RNA annealing activity of A1 may play a role in pre-mRNA splicing and other aspects of nuclear mRNA metabolism. PMID:1371011

Munroe, S H; Dong, X F

1992-02-01

322

Effects of nickel ions implantation and subsequent thermal annealing on structural and magnetic properties of titanium dioxide  

NASA Astrophysics Data System (ADS)

Wide bandgap semiconducting rutile (TiO2) doped with 3d-elements is a promising material for spintronic applications. In our work a composite material of TiO2:Ni has been formed by using implantation of Ni+ ions into single-crystalline (100)- and (001)- plates of TiO2. Sub-micron magnetic layers of TiO2 containing nickel dopant have been obtained at high implantation fluence of 1×1017 ion/cm2. A part of the implanted samples was then annealed in vacuum at different temperatures Tann = 450-1200 K for 30 min. The influence of the implantation fluence, crystalline orientation, as well as subsequent annealing on the structural and magnetic properties of the nickel-implanted TiO2 have been investigated by using X-ray photoelectron spectroscopy, scanning electron microscopy and coil magnetometry techniques.

Vakhitov, I. R.; Lyadov, N. M.; Valeev, V. F.; Nuzhdin, V. I.; Tagirov, L. R.; Khaibullin, R. I.

2014-12-01

323

Effects of Post-Deposition Annealing on the Copper Films Electrodeposited on the ECR Plasma Cleaned Copper Seed Layer  

NASA Astrophysics Data System (ADS)

Thin copper films were grown by electrodeposition on copper seed layers which were grown by sputtering of an ultra-pure copper target on tantalum nitride-coated silicon wafers and subsequently, cleaned in ECR plasma. The copper films were then subjected to i) vacuum annealing, ii) rapid thermal annealing (RTA) and iii) rapid thermal nitriding (RTN) at various temperatures over different periods of time. XRD, SEM, AFM and resistivity measurements were done to ascertain the optimum heat treatment condition for obtaining film with minimum resistivity, predominantly (111)-oriented and smoother surface morphology. The as-deposited film has a resistivity of ˜6.3 ??\\cdotcm and a relatively small intensity ratio of (111) and (200) peaks. With heat treatment, the resistivity decreases and the (111) peak becomes dominant, along with improved smoothness of the copper film. The optimum condition (with a resistivity of 1.98 ??\\cdotcm) is suggested as the rapid thermal nitriding at 400°C for 120 s.

Lee, Hanseung; Chakrabarti, Kuntal; Lee, Chongmu

2002-12-01

324

A combined ion-sputtering and electron-beam annealing device for the in vacuo postpreparation of scanning probes  

NASA Astrophysics Data System (ADS)

We describe the setup, characteristics, and application of an in vacuo ion-sputtering and electron-beam annealing device for the postpreparation of scanning probes (e.g., scanning tunneling microscopy (STM) tips) under ultrahigh vacuum (UHV) conditions. The proposed device facilitates the straightforward implementation of a common two-step cleaning procedure, where the first step consists of ion-sputtering, while the second step heals out sputtering-induced defects by thermal annealing. In contrast to the standard way, no dedicated external ion-sputtering gun is required with the proposed device. The performance of the described device is demonstrated by SEM micrographs and energy dispersive x-ray characterization of electrochemically etched tungsten tips prior and after postprocessing.

Eder, Georg; Schlögl, Stefan; Macknapp, Klaus; Heckl, Wolfgang M.; Lackinger, Markus

2011-03-01

325

The effect of annealing on structural and optical properties of ?-Fe2O3/CdS/?-Fe2O3 multilayer heterostructures  

NASA Astrophysics Data System (ADS)

Multilayered thin film heterostructures of ?-Fe2O3/CdS/?-Fe2O3 were prepared through physical vapor deposition. Each ?-Fe2O3 layer was deposited by e-beam evaporation of iron in an oxygen atmosphere. The CdS layer was deposited by thermal evaporation in a vacuum. The effect of post annealing of multilayered thin films in air in the temperature range 250 °C to 450 °C was investigated. Structural characterization indicated the growth of the ?-Fe2O3 phase with a polycrystalline structure without any CdS crystalline phase. As-deposited multilayer heterostructures were amorphous and transformed into polycrystalline upon annealing. The surface modification of the films during annealing was revealed by scanning electron microscopy. Spectrophotometric measurements were used to determine the optical properties, including the transmittance, absorbance, and band gap. All the films had both direct as well as indirect band gaps.

Saleem, M.; Durrani, S. M. A.; Saheb, N.; Al-Kuhaili, M. F.; Bakhtiari, I. A.

2014-11-01

326

Effect of thermal annealing on structure and optical band gap of amorphous Se{sub 72}Te{sub 25}Sb{sub 3} thin films  

SciTech Connect

Thin films of a?Se{sub 72}Te{sub 25}Sb{sub 3} were prepared by vacuum evaporation technique in a base pressure of 10{sup ?6} Torr on to well cleaned glass substrate. a?Se{sub 72}Te{sub 25}Sb{sub 3} thin films were annealed at different temperatures below their crystallization temperatures for 2h. The structural analysis of the films has been investigated using X-ray diffraction technique. The optical band gap of as prepared and annealed films as a function of photon energy in the wavelength range 400–1100 nm has been studied. It has been found that the optical band gap decreases with increasing annealing temperatures in the present system.

Dwivedi, D. K., E-mail: dwivedidkphys@rediffmail.com; Pathak, H. P., E-mail: dwivedidkphys@rediffmail.com; Shukla, Nitesh [Amorphous Semiconductor Research Lab, Department of Physics, M.M.M. E.C., Gorakhpur-273010 (India); Kumar, Vipin [Department of Physics, K.I.E.T., Ghaziabad-201206 (India)

2014-04-24

327

The correlation of damping capacity with grain-boundary precipitates in Fe–Cr-based damping alloys annealed at high temperature  

Microsoft Academic Search

We report the damping capacity measurements and grain-boundary (GB) precipitates observations on a set of four Fe–Cr-based ferromagnetic damping alloys annealed at 1473K. The alloys were prepared by vacuum induction melt furnace of which each cast ingot weighed 15kg. The technique of inverted torsion pendulum was employed to measure the damping capacity, and a field emission scanning electron microscope (FESEM)

Weiguo Wang; Bangxin Zhou

2004-01-01

328

RF cavity vacuum interlock system  

NASA Astrophysics Data System (ADS)

The Continuous Electron Beam Accelerator Facility (CEBAF), a continuous wave (CW) 4 GeV Electron Accelerator is undergoing construction in Newport News, Virginia. When completed in 1994, the accelerator will be the largest installation of radio-frequency superconductivity. Production of cryomodules, the fundamental building block of the machine, has started. A cryomodule consists of four sets of pairs of 1497 MHz, 5 cell niobium cavities contained in separate helium vessels and mounted in a cryostat with appropriate end caps for helium supply and return. Beam vacuum of the cavities, the connecting beam piping, the waveguides, and the cryostat insulating vacuum are crucial to the performance of the machine. The design and initial experience of the vacuum systems for the first 2 1/4 cryomodules that makeup the 45 MEV injector are discussed.

Jordan, K.; Crawford, K.; Bundy, R.; Dylla, H. F.; Heckman, J.; Marshall, J.; Nichols, R.; Osullivan, S.; Preble, J.; Robb, J.

1992-03-01

329

D-Zero Vacuum System  

SciTech Connect

The system pumping speed was calculated by taking the reciprocal of the sum of the reciprocal pump speed and the reciprocal line conductances. The conductances of the pipe were calculated from the following formulas taken from the Varian vacuum manual. This report updates the original to reflect the pumping curves and basic vacuum system characteristics for the purchased components and installed piping of the D-Zero vacuum system. The system consists of two Edward's E2M275 two stage mechanical pumps, a Leybold-Heraeus WSU2000 Blower and three Varian 4' diffusion pumps (one for each cryostat). Individual pump and system pumping speed curves and a diagram of the system is included.

Wintercorn, S.J.; /Fermilab

1986-04-07

330

Tritium and helium retained in fast-neutron-irradiated lithium ceramics as measured by high-temperature vacuum extraction  

SciTech Connect

A vacuum apparatus was designed and constructed for the rapid measurement of retained helium and tritium in lithium ceramics. The apparatus eliminated the limitations and errors associated with the acid dissolution technique and the previous vacuum annealing technique (below the melting point) and allowed more accurate and less expensive analysis techniques. Tritium retention in Li/sub 2/ZrO/sub 3/ was significantly less than in the other ceramics. Tritium retention appears to possess a proportional dependence to burnup. A review of available models reveals that none fully describe the absolute magnitude or the relationship of retention to temperature or burnup so that a model which considers irradiation effects is desired.

Hollenberg, G.W.; Baldwin, D.L.

1987-01-01

331

Simulated annealing for tensor network states  

NASA Astrophysics Data System (ADS)

Markov chains for probability distributions related to matrix product states and one-dimensional Hamiltonians are introduced. With appropriate ‘inverse temperature’ schedules, these chains can be combined into a simulated annealing scheme for ground states of such Hamiltonians. Numerical experiments suggest that a linear, i.e., fast, schedule is possible in non-trivial cases. A natural extension of these chains to two-dimensional settings is next presented and tested. The obtained results compare well with Euclidean evolution. The proposed Markov chains are easy to implement and are inherently sign problem free (even for fermionic degrees of freedom).

Iblisdir, S.

2014-10-01

332

Annealing relaxation of ultrasmall gold nanostructures  

NASA Astrophysics Data System (ADS)

Except serving as an excellent gift on proper occasions, gold finds applications in life sciences, particularly in diagnostics and therapeutics. These applications were made possible by gold nanoparticles, which differ drastically from macroscopic gold. Versatile surface chemistry of gold nanoparticles allows coating with small molecules, polymers, biological recognition molecules. Theoretical investigation of nanoscale gold is not trivial, because of numerous metastable states in these systems. Unlike elsewhere, this work obtains equilibrium structures using annealing simulations within the recently introduced PM7-MD method. Geometries of the ultrasmall gold nanostructures with chalcogen coverage are described at finite temperature, for the first time.

Chaban, Vitaly

2015-01-01

333

Vacuum Plasma Spraying Replaces Electrodeposition  

NASA Technical Reports Server (NTRS)

Vacuum plasma spraying used to fabricate large parts with complicated contours and inner structures, without uninspectable welds. Reduces time, and expense of fabrication. Wall of combustion chamber built up inside of outer nickel-alloy jacket by plasma spraying. Particles of metal sprayed partially melted in plasma gun and thrown at supersonic speed toward deposition surface. Vacuum plasma-spray produces stronger bond between the grooves and covering layer completing channels and wall of combustion chamber. In tests, bond withstood pressure of 20 kpsi, three times allowable limit by old method.

Holmes, Richard R.; Power, Chris; Burns, David H.; Daniel, Ron; Mckechnie, Timothy N.

1992-01-01

334

Compactification, Vacuum Energy and Quintessence  

E-print Network

We study the possibility that the vacuum energy density of scalar and internal-space gauge fields arising from the process of dimensional reduction of higher dimensional gravity theories plays the role of quintessence. We show that, for the multidimensional Einstein-Yang-Mills system compactified on a $R \\times S^3 \\times S^d$ topology, there are classically stable solutions such that the observed accelerated expansion of the Universe at present can be accounted for without upsetting structure formation scenarios or violating observational bounds on the vacuum energy density.

M. C. Bento; O. Bertolami

1999-05-20

335

Relativistic invariance of the vacuum  

NASA Astrophysics Data System (ADS)

Relativistic invariance of the vacuum is (or follows from) one of the Wightman axioms, which is commonly believed to be true. Without these axioms, here we present a direct and general proof of continuous relativistic invariance of all real-time vacuum correlations of fields, not only scattering (forward in time), based on closed time path formalism. The only assumptions are basic principles of relativistic quantum field theories: the relativistic invariance of the Lagrangian, of the form including known interactions (electromagnetic, weak and strong), and standard rules of quantization. The proof is in principle perturbative leaving a possibility of spontaneous violation of invariance. Time symmetry is, however, manifestly violated.

Bednorz, Adam

2013-12-01

336

Method for vacuum fusion bonding  

DOEpatents

An improved vacuum fusion bonding structure and process for aligned bonding of large area glass plates, patterned with microchannels and access holes and slots, for elevated glass fusion temperatures. Vacuum pumpout of all components is through the bottom platform which yields an untouched, defect free top surface which greatly improves optical access through this smooth surface. Also, a completely non-adherent interlayer, such as graphite, with alignment and location features is located between the main steel platform and the glass plate pair, which makes large improvements in quality, yield, and ease of use, and enables aligned bonding of very large glass structures.

Ackler, Harold D. (Sunnyvale, CA); Swierkowski, Stefan P. (Livermore, CA); Tarte, Lisa A. (Livermore, CA); Hicks, Randall K. (Stockton, CA)

2001-01-01

337

QED vacuum loops and Inflation  

E-print Network

A QED-based model of a new version of Vacuum Energy has recently been suggested, which leads to a simple, finite, one parameter representation of Dark Energy. An elementary, obvious, but perhaps radical generalization is then able to describe both Dark Energy and Inflation in the same framework of Vacuum Energy. One further, obvious generalization then leads to a relation between Inflation and the Big Bang, to the automatic inclusion of Dark Matter, and to a possible understanding of the birth (and death) of a Universe.

H. M. Fried; Y. Gabellini

2014-11-19

338

Experimental Studies of Light Emission Phenomena in Superconducting RF Cavitites  

SciTech Connect

Experimental studies of light emission phenomena in superconducting RF cavities, which we categorize under the general heading of cavity lights, are described. The cavity lights data, which were obtained using a small CCD video camera, were collected in a series of nine experimental runs ranging from {approx} 1/2 to {approx} 2 h in duration. The video data were recorded on a standard VHS tape. As the runs progressed, additional instrumentation was added. For the last three runs a LabVIEW controlled data acquisition system was included. These runs furnish evidence for several, possibly related, light emission phenomena. The most intriguing of these is what appear to be small luminous objects {le} 1.5 mm in size, freely moving about in the vacuum space, generally without wall contact, as verified by reflections of the tracks in the cavity walls. In addition, on a number of occasions, these objects were observed to bounce off of the cavity walls. The wall-bounce aspect of most of these events was clearly confirmed by pre-bounce and post-bounce reflections concurrent with the tracks. In one of the later runs, a mode of behavior was observed that was qualitatively different from anything observed in the earlier runs. Perhaps the most perplexing aspect of this new mode was the observation of as many as seven luminous objects arrayed in what might be described as a macromolecular formation, coherently moving about in the interior of the cavity for extended periods of time, evidently without any wall contact. It is suggested that these mobile luminous objects are without explanation within the realm of established physics. Some remarks about more exotic theoretical possibilities are made, and future plans are discussed.

Anthony, P.L.; /SLAC; Delayen, J.R.; /Jefferson Lab; Fryberger, D.; /SLAC; Goree, W.S.; Mammosser, J.; /Jefferson Lab /SNS Project, Oak Ridge; Szalata, Z.M.; II, J.G.Weisend /SLAC

2009-08-04

339

Large-scale uniform bilayer graphene prepared by vacuum graphitization of 6H-SiC(0001) substrates.  

PubMed

We report on the preparation of large-scale uniform bilayer graphenes on nominally flat Si-polar 6H-SiC(0001) substrates by flash annealing in ultrahigh vacuum. The resulting graphenes have a single thickness of one bilayer and consist of regular terraces separated by the triple SiC bilayer steps on the 6H-SiC(0001) substrates. In situ scanning tunneling microscopy reveals that suppression of pit formation on terraces and uniformity of SiC decomposition at step edges are the key factors to the uniform thickness. By studying the surface morphologies prepared under different annealing rates, it is found that the annealing rate is directly related to SiC decomposition, diffusion of the released Si/C atoms and strain relaxation, which together determine the final step structure and density of defects. PMID:23306457

Wang, Qingyan; Zhang, Wenhao; Wang, Lili; He, Ke; Ma, Xucun; Xue, Qikun

2013-03-01

340

Interfacial layer formation during high-temperature annealing of ZrO2 thin films on Si  

NASA Astrophysics Data System (ADS)

High-k materials deposited directly on silicon exhibit an interfacial layer between the grown layer and the underlying substrate. This is of particular concern in metal-oxide-semiconductor technologies where these layers have a deleterious effect on the overall capacitance of the resulting devices. In this letter, the growth and properties of this silicatelike interfacial layer are examined after postdeposition anneals in a vacuum, inert, and oxidizing atmospheres. X-ray reflectivity, Fourier transform infrared spectroscopy, and x-ray photoelectron spectroscopy have been used to characterize the growth and properties of this interfacial layer.

Howard, J. M.; Craciun, V.; Essary, C.; Singh, R. K.

2002-10-01

341

A Novel Metal-Rich Anneal for In Vacuo Passivation of High-Aspect-Ratio Mercury Cadmium Telluride Surfaces  

NASA Astrophysics Data System (ADS)

A new method for Cd-rich annealing of mercury cadmium telluride (MCT) was developed based on the observation that the deposition of Cd onto MCT by vacuum evaporation became self-limiting whenever the substrate temperature was above 70°C regardless of the Cd evaporation rate. Preliminary results indicated that this new method may be suitable for passivation of high-aspect-ratio MCT surfaces, for passivation at low temperatures, for in vacuo operation, and/or for vacancy annihilation in MCT. Furthermore, the process can be carried out in the conventional open-tube reactors used for molecular beam epitaxy, metalorganic chemical vapor deposition, and physical vapor deposition.

Wan, Chang-Feng; Orent, Thomas; Myers, Thomas; Bhat, Ishwara; Stoltz, Andy; Pellegrino, Joe

2013-11-01

342

Viscoelastic leveling of annealed thin polystyrene films.  

PubMed

Theoretical and experimental work on nanoscale viscoelastic flows of polystyrene melts is presented. The reflow above the glass transition temperature (T(g)) of a continuous patterned film is characterized. Attention is paid to the topographical consequences of the flow rather than to the temporal description of the leveling of the film. In the framework of capillary wave theory, it is shown that only the shortest spatial wavelengths of the topography exhibit an elastic behavior, while long waves follow a viscous decay. The threshold wavelength depends on the surface tension, on the elastic plateau modulus, and, for ultrathin films, on the film thickness. Besides, for polystyrene, this threshold is a nanoscale parameter and weakly depends on the temperature of annealing. Experiments are conducted on polystyrene 130 kg/mol submicrometer films. The samples are embossed using thermal nanoimprint technology and then annealed at different temperatures between T(g) + 10 °C and T(g) + 50 °C. The smoothed topographies of the films are measured by atomic force microscopy and compared to a single-mode Maxwell leveling model and a more elaborated model based on reptation theory. PMID:24850138

Rognin, Etienne; Landis, Stefan; Davoust, Laurent

2014-06-17

343

Burst annealing of high temperature GaAs solar cells  

NASA Technical Reports Server (NTRS)

One of the major limitations of solar cells in space power systems is their vulnerability to radiation damage. One solution to this problem is to periodically heat the cells to anneal the radiation damage. Annealing was demonstrated with silicon cells. The obstacle to annealing of GaAs cells was their susceptibility to thermal damage at the temperatures required to completely anneal the radiation damage. GaAs cells with high temperature contacts and encapsulation were developed. The cells tested are designed for concentrator use at 30 suns AMO. The circular active area is 2.5 mm in diameter for an area of 0.05 sq cm. Typical one sun AMO efficiency of these cells is over 18 percent. The cells were demonstrated to be resistant to damage after thermal excursions in excess of 600 C. This high temperature tolerance should allow these cells to survive the annealing of radiation damage. A limited set of experiments were devised to investigate the feasibility of annealing these high temperature cells. The effect of repeated cycles of electron and proton irradiation was tested. The damage mechanisms were analyzed. Limitations in annealing recovery suggested improvements in cell design for more complete recovery. These preliminary experiments also indicate the need for further study to isolate damage mechanisms. The primary objective of the experiments was to demonstrate and quantify the annealing behavior of high temperature GaAs cells. Secondary objectives were to measure the radiation degradation and to determine the effect of repeated irradiation and anneal cycles.

Brothers, P. R.; Horne, W. E.

1991-01-01

344

Spooky Phenomena in Two-Photon Processes  

NASA Astrophysics Data System (ADS)

A spooky phenomenon in two-photon coherent atomic absorption was discussed in 1980 [M. C. Li, Phys. Rev. A 22 (1980) 1323]. The absorption was initiated by two different laser sources. Classically, it is impossible for atoms to transit coherently in the absorption process, but quantum mechanically it is. This is one of the spooky phenomena in quantum mechanic. Around1990, there were very active experimental pursuits on a spooky phenomenon of two photons emitted from crystal parametric down conversion. The two-photon coherent atomic absorption process contained all basic ingredients as that in crystal parametric down conversion. However, the former arises from two different laser sources. The atom entangles two photons together and becomes a correlatior. The latter arises from a single laser source and two photons are entangled with each other at emission. These two spooky phenomena have been considered as disjointed. The present talk will review two spooky phenomena, and point out their similarities. The investigation on quantum spooky phenomena has led to quantum computing and quantum encryption. It is a hope that the present will stimulate the interest on bring in these two disjointed phenomena together and provide clues in advancing quantum computing and quantum encryption.

Li, Ming-Chiang

2006-05-01

345

Investigating the students' understanding of surface phenomena  

NASA Astrophysics Data System (ADS)

This study investigated students' understanding of surface phenomena. The main purpose for conducting this research endeavor was to understand how students think about a complex topic about which they have little direct or formal instruction. The motivation for focusing on surface phenomena stemmed from an interest in integrating research and education. Despite the importance of surfaces and interfaces in research laboratories, in technological applications, and in everyday experiences, no previous systematic effort was done on pedagogy related to surface phenomena. The design of this research project was qualitative, exploratory, based on a Piagetian semi-structured clinical piloted interview, focused on obtaining a longitudinal view of the intended sample. The sampling was purposeful and the sample consisted of forty-four undergraduate students at Kansas State University. The student participants were enrolled in physics classes that spanned a wide academic spectrum. The data were analyzed qualitatively. The main themes that emerged from the analysis were: (a) students used analogies when confronted with novel situations, (b) students mixed descriptions and explanations, (c) students used the same explanation for several phenomena, (d) students manifested difficulties transferring the meaning of vocabulary across discipline boundaries, (e) in addition to the introductory chemistry classes, students used everyday experiences and job-related experiences as sources of knowledge, and (f) students' inquisitiveness and eagerness to investigate and discuss novel phenomena seemed to peak about the time students were enrolled in second year physics classes.

Hamed, Kastro Mohamad

1999-11-01

346

Anomalous Light Phenomena vs. Bioelectric Brain Activity  

NASA Astrophysics Data System (ADS)

We present a research proposal concerning the instrumented investigation of anomalous light phenomena that are apparently correlated with particular mind states, such as prayer, meditation or psi. Previous research by these authors demonstrate that such light phenomena can be monitored and measured quite efficiently in areas of the world where they are reported in a recurrent way. Instruments such as optical equipment for photography and spectroscopy, VLF spectrometers, magnetometers, radar and IR viewers were deployed and used massively in several areas of the world. Results allowed us to develop physical models concerning the structural and time-variable behaviour of light phenomena, and their kinematics. Recent insights and witnesses have suggested to us that a sort of "synchronous connection" seems to exist between plasma-like phenomena and particular mind states of experiencers who seem to trigger a light manifestation which is very similar to the one previously investigated. The main goal of these authors is now aimed at the search for a concrete "entanglement-like effect" between the experiencer's mind and the light phenomena, in such a way that both aspects are intended to be monitored and measured simultaneously using appropriate instrumentation. The goal of this research project is twofold: a) to verify quantitatively the existence of one very particular kind of mind-matter interaction and to study in real time its physical and biophysical manifestations; b) to repeat the same kind of experiment using the same test-subject in different locations and under various conditions of geomagnetic activity.

Teodorani, M.; Nobili, G.

347

Vacuum barrier for excimer lasers  

DOEpatents

A barrier for separating the vacuum area of a diode from the pressurized gas area of an excimer laser. The barrier is a composite material comprising layers of a metal such as copper, along with layers of polyimide, and a matrix of graphite fiber yarns impregnated with epoxy. The barrier is stronger than conventional foil barriers, and allows greater electron throughput. 3 figs.

Shurter, R.P.

1992-09-15

348

Vacuum-insulated catalytic converter  

DOEpatents

A catalytic converter has an inner canister that contains catalyst-coated substrates and an outer canister that encloses an annular, variable vacuum insulation chamber surrounding the inner canister. An annular tank containing phase-change material for heat storage and release is positioned in the variable vacuum insulation chamber a distance spaced part from the inner canister. A reversible hydrogen getter in the variable vacuum insulation chamber, preferably on a surface of the heat storage tank, releases hydrogen into the variable vacuum insulation chamber to conduct heat when the phase-change material is hot and absorbs the hydrogen to limit heat transfer to radiation when the phase-change material is cool. A porous zeolite trap in the inner canister absorbs and retains hydrocarbons from the exhaust gases when the catalyst-coated substrates and zeolite trap are cold and releases the hydrocarbons for reaction on the catalyst-coated substrate when the zeolite trap and catalyst-coated substrate get hot.

Benson, David K. (Golden, CO)

2001-01-01

349

Plates for vacuum thermal fusion  

DOEpatents

A process for effectively bonding arbitrary size or shape substrates. The process incorporates vacuum pull down techniques to ensure uniform surface contact during the bonding process. The essence of the process for bonding substrates, such as glass, plastic, or alloys, etc., which have a moderate melting point with a gradual softening point curve, involves the application of an active vacuum source to evacuate interstices between the substrates while at the same time providing a positive force to hold the parts to be bonded in contact. This enables increasing the temperature of the bonding process to ensure that the softening point has been reached and small void areas are filled and come in contact with the opposing substrate. The process is most effective where at least one of the two plates or substrates contain channels or grooves that can be used to apply vacuum between the plates or substrates during the thermal bonding cycle. Also, it is beneficial to provide a vacuum groove or channel near the perimeter of the plates or substrates to ensure bonding of the perimeter of the plates or substrates and reduce the unbonded regions inside the interior region of the plates or substrates.

Davidson, James C. (Livermore, CA); Balch, Joseph W. (Livermore, CA)

2002-01-01

350

Quantum Vacuum Structure and Cosmology  

SciTech Connect

Contemporary physics faces three great riddles that lie at the intersection of quantum theory, particle physics and cosmology. They are: (1) The expansion of the universe is accelerating - an extra factor of two appears in the size; (2) Zero-point fluctuations do not gravitate - a matter of 120 orders of magnitude; and (3) The 'True' quantum vacuum state does not gravitate. The latter two are explicitly problems related to the interpretation and the physical role and relation of the quantum vacuum with and in general relativity. Their resolution may require a major advance in our formulation and understanding of a common unified approach to quantum physics and gravity. To achieve this goal we must develop an experimental basis and much of the discussion we present is devoted to this task. In the following, we examine the observations and the theory contributing to the current framework comprising these riddles. We consider an interpretation of the first riddle within the context of the universe's quantum vacuum state, and propose an experimental concept to probe the vacuum state of the universe.

Rafelski, Johann; Labun, Lance; Hadad, Yaron; /Arizona U. /Munich U.; Chen, Pisin; /Taiwan, Natl. Taiwan U. /KIPAC, Menlo Park /SLAC

2011-12-05

351

Cleaner Vacuum-Bag Curing  

NASA Technical Reports Server (NTRS)

Improvement upon recommended procedures saves time and expense. Autoclave molding in vacuum bag cleaner if adhesive-backed covering placed around caul plate as well as on mold plate. Covering easy to remove after curing and leaves caul plate free of resin deposits.

Clemons, J. M.; Penn, B. G.; Ledbetter, Frank E., III; Daniels, J. G.

1987-01-01

352

HIGH PRODUCTIVITY VACUUM BLASTING SYSTEM  

SciTech Connect

The purpose of the project is to increase the productivity and economics of existing vacuum blasting technology. This technology is used to remove radioactive contamination, PCB's and lead-base paint and provides worker and environmental protection by continuously recycling the blast media and the full containment of the dust generated in the process.

Dr. M.A. Ebadian

2000-01-13

353

Vacuum barrier for excimer lasers  

DOEpatents

A barrier for separating the vacuum area of a diode from the pressurized gas area of an excimer laser. The barrier is a composite material comprising layers of a metal such as copper, along with layers of polyimide, and a matrix of graphite fiber yarns impregnated with epoxy. The barrier is stronger than conventional foil barriers, and allows greater electron throughput.

Shurter, Roger P. (Jemez Springs, NM)

1992-01-01

354

Vacuum Seal Permits Limited Rotation  

NASA Technical Reports Server (NTRS)

Flexible metal seal permits rotation of object in vacuum chamber. Seal made from two cylindrical azimuthally fluted bellows attached to ends of cylindrical axially fluted bellows with connecting tubes at both ends. Designed for rotation of sample probes in electron spectroscopy for chemical analysis (ESCA), other applications likely.

Lombardi, F.

1985-01-01

355

Vacuum-injection-molding processing  

SciTech Connect

An improved processing technique for the manufacture of glass or glass-ceramic headers has been developed. Vacuum-injection molding is a relatively easy processing technique that has been used successfully in the fabrication of several different advantages in certain applications over the present fabrication process which uses glass preforms.

Kramer, D.P.; Massey, R.T.

1982-01-01

356

Vacuum mounting for piezoelectric transducers  

NASA Technical Reports Server (NTRS)

Special housing couples piezoelectric transducers to nonporous surfaces for ultrasonic or acoustic-emission testing. Device, while providing sound isolation on flat or nonflat surfaces, can be attached and detached quickly. Vacuum sealing mechanism eliminates need for permanent or semipermanent bonds, viscous coupling liquids, weights, magnets, tape, or springs ordinarily used.

Tiede, D. A.

1977-01-01

357

New process of ion surface modification of compressor steel in the vacuum arc plasma of titanium  

NASA Astrophysics Data System (ADS)

A new process of ion modification of the surfaces of EI961 and EP866 compressor steels by titanium in the plasma of high-current vacuum arc discharge in an ion-plasma MAP-3 device is studied and compared to the thermodiffusion solid-phase saturation of these steels by titanium under temperature-time conditions that are identical to the ion modification conditions. The phase and elemental compositions of the surfaces of the samples modified in titanium plasma at various bias voltages and the samples with a titanium coating after vacuum thermodiffusion annealing are analyzed. The phase state of the surfaces of the EI961 and EP866 steel samples is shown to begin to change during ion treatment in titanium plasma at a bias voltage of 150 V and an ion heating temperature of 470-480°C. No changes are detected in the phase state of the surfaces of the samples coated with titanium after vacuum diffusion annealing at a temperature of 1050°C.

Muboyadzhyan, S. A.; Azarovskii, E. N.

2013-11-01

358

Static Friction Phenomena The following static friction phenomena have a direct dependency on velocity.  

E-print Network

Coulomb Friction Viscous Friction Stribeck Friction Static Friction Phenomena The following static friction phenomena have a direct dependency on velocity. Static Friction Model: Friction force opposes the direction of motion when the sliding velocity is zero. Coulomb Friction Model: Friction force

Simpkins, Alex

359

Low loss hollow optical-waveguide connection from atmospheric pressure to ultra-high vacuum  

NASA Astrophysics Data System (ADS)

A technique for optically accessing ultra-high vacuum environments, via a photonic-crystal fiber with a long small hollow core, is described. The small core and the long bore enable a pressure ratio of over 108 to be maintained between two environments, while permitting efficient and unimpeded delivery of light, including ultrashort optical pulses. This delivery can be either passive or can encompass nonlinear optical processes such as optical pulse compression, deep UV generation, supercontinuum generation, or other useful phenomena.

Ermolov, A.; Mak, K. F.; Tani, F.; Hölzer, P.; Travers, J. C.; Russell, P. St. J.

2013-12-01

360

Study of the optical properties of etched alpha tracks in annealed and non-annealed CR-39 polymeric detectors  

NASA Astrophysics Data System (ADS)

The UV-visible absorption spectra of virgin and alpha particle-irradiated, annealed and non-annealed CR-39 polymeric track detectors were investigated using a UV-visible spectrometer (Shimadzu mini 1240). Isothermal annealing experiments were carried out on poly allyl diglycol carbonate (PADC) films based nuclear track detectors (NTDs) exposed to a 241Am source. A shifting and broadening of the UV-visible peaks was observed as a result of the etched alpha tracks in the non-annealed and annealed PADC films. The UV-visible spectra of the virgin and non-annealed ?-irradiated PADC polymer films displayed a decreasing trend in their optical energy band gaps, both direct and indirect, whereas those measured for the annealed ?-irradiated ones showed no significant change. This drop in the energy band gap with increasing fluence is discussed on the basis of the alpha particle- and thermal annealing-induced modifications in the PADC polymeric detector. The results clearly showed that the values for the indirect energy band gap were lower than the corresponding values for the direct band gap. In addition, the Urbach energy was estimated from the Urbach edge, and exhibited roughly the same trend as the optical band gap. Finally, this study presents new results showing that the annealed PADC films were highly insensitive to alpha particles.

Saad, A. F.; Al-Faitory, N. M.; Mohamed, R. A.

2014-04-01

361

Quantum optical phenomena in semiconductor quantum dots  

E-print Network

Quantum optical phenomena are explored in artificial atoms well known as semiconductor quantum dots, in the presence of excitons and biexcitons. The analytical results are obtained using the conventional time-dependent perturbation technique. Numerical estimations are made for arealistic sample of CdS quantum dots in a high-Q cavity. Quantum optical phenomena such as quantum Rabi oscillations, photon statistics and collapse and revival of population inversion in exciton and biexciton states are observed. In the presence of biexcitons the collapse and revival phenomenon becomes faster due to the strong coupling of biexciton with cavity field.

J. Thomas Andrews

2002-11-22

362

Modeling of fundamental phenomena in welds  

SciTech Connect

Recent advances in the mathematical modeling of fundamental phenomena in welds are summarized. State-of-the-art mathematical models, advances in computational techniques, emerging high-performance computers, and experimental validation techniques have provided significant insight into the fundamental factors that control the development of the weldment. The current status and scientific issues in the areas of heat and fluid flow in welds, heat source metal interaction, solidification microstructure, and phase transformations are assessed. Future research areas of major importance for understanding the fundamental phenomena in weld behavior are identified.

Zacharia, T.; Vitek, J.M. [Oak Ridge National Lab., TN (United States); Goldak, J.A. [Carleton Univ., Ottawa, Ontario (Canada); DebRoy, T.A. [Pennsylvania State Univ., University Park, PA (United States); Rappaz, M. [Ecole Polytechnique Federale de Lausanne (Switzerland); Bhadeshia, H.K.D.H. [Cambridge Univ. (United Kingdom)

1993-12-31

363

Coastal Meteorological Phenomena in CalNex  

NASA Astrophysics Data System (ADS)

Coastal meteorology plays an important role in air quality and climate in California. During the 2010 CalNex experiment, several phenomena affected the campaign observations. Among these were coastal eddies and outflow in Santa Monica Bay and the Los Angeles Bight; marine stratus and stratocumulus; and the land-sea breeze cycle on a variety of spatial scales, including transport from the San Francisco Bay Area into the Central Valley. In this presentation, we will describe these phenomena as they were seen in model forecasts and hindcast simulations, and compare those simulations to the relevant meteorological observations.

Angevine, W. M.; Brioude, J.

2010-12-01

364

The vacuum-vacuum amplitude and Bogoliubov coefficients  

SciTech Connect

We consider the problem of fixing the phases of Bogoliubov coefficients in quantum electrodynamics such that the vacuum-vacuum amplitude can be expressed via them. For a constant electric field and particles with spins of 0 and 1/2, this is done starting from the definition of these coefficients. Using the symmetry between electric and magnetic fields, we extend the result to a constant electromagnetic field. It turns out that for a constant magnetic field, it is necessary to distinguish the in- and out-states, although they differ only by a phase factor. For a spin-1 particle with a gyromagnetic of ratio g = 2, this approach fails and we reconsider the problem using the proper-time method.

Nikishov, A.I. [Lebedev Physical Institute, Russian Academy of Sciences, Moscow, 119991 (Russian Federation)

2003-02-01

365

A Review of Maintenance of Vacuum inside Vacuum Insulation Panels  

NASA Astrophysics Data System (ADS)

The growing concerns over global energy crisis and the phasing out of polyurethane foams blown with CFC-11, which has high Ozone Depletion Potential(ODP), have pushed thermal insulation technology to improve its efficiency. Vacuum Insulation Panel(VIP) has been regarded as a super thermal insulation material with a thermal resistance of about 5-10 times higher than conventional thermal insulation. Appropriate vacuum in VIP is one of the most important factors contributing to the long term heat insulation performance of VIP. In this paper, the researches on three factors, which influence internal pressure inside VIP, including gas and water vapor permeation through the barrier, gas absorption by getters and desiccants and outgassing of the kernel, were reviewed respectively. Following this, the research emphasis and suggestions, which should be paid attention to, were summarized.

Yang, Chun Guang; Xu, Lie

366

Ceramic-to-metal vacuum seal  

NASA Technical Reports Server (NTRS)

Knife-edge sealing technique forms reliable, vacuum-tight bonds between materials having very different thermal-expansion characteristics. Seal is thin and flexible and absorb shear, hoop, and bonding stresses at joint so that seal remains vacuum tight.

Sackerlotzky, O. H.

1979-01-01

367

Vacuum casting of thick polymeric films  

NASA Technical Reports Server (NTRS)

Bubble formation and layering, which often plague vacuum-evaporated films, are prevented by properly regulating process parameters. Vacuum casting may be applicable to forming thick films of other polymer/solvent solutions.

Cuddihy, E. F.; Moacanin, J.

1979-01-01

368

Ultrathin gate valve for high vacuum operation  

NASA Technical Reports Server (NTRS)

Thin, compact, high-vacuum gate valve used to join two vacuum systems together demonstrates multiple operation reliability. Valve measurements and non-protruding handle make valve usable in confined areas.

Ugiansky, R. J.

1971-01-01

369

Switching Circuit for Shop Vacuum System  

NASA Technical Reports Server (NTRS)

No internal connections to machine tools required. Switching circuit controls vacuum system draws debris from grinders and sanders in machine shop. Circuit automatically turns on vacuum system whenever at least one sander or grinder operating. Debris safely removed, even when operator neglects to turn on vacuum system manually. Pickup coils sense alternating magnetic fields just outside operating machines. Signal from any coil or combination of coils causes vacuum system to be turned on.

Burley, R. K.

1987-01-01

370

Encapsulated Annealing: Enhancing the Plasmon Quality Factor in Lithographically–Defined Nanostructures  

PubMed Central

Lithography provides the precision to pattern large arrays of metallic nanostructures with varying geometries, enabling systematic studies and discoveries of new phenomena in plasmonics. However, surface plasmon resonances experience more damping in lithographically–defined structures than in chemically–synthesized nanoparticles of comparable geometries. Grain boundaries, surface roughness, substrate effects, and adhesion layers have been reported as causes of plasmon damping, but it is difficult to isolate these effects. Using monochromated electron energy–loss spectroscopy (EELS) and numerical analysis, we demonstrate an experimental technique that allows the study of these effects individually, to significantly reduce the plasmon damping in lithographically–defined structures. We introduce a method of encapsulated annealing that preserves the shape of polycrystalline gold nanostructures, while their grain-boundary density is reduced. We demonstrate enhanced Q–factors in lithographically–defined nanostructures, with intrinsic damping that matches the theoretical Drude damping limit. PMID:24986023

Bosman, Michel; Zhang, Lei; Duan, Huigao; Tan, Shu Fen; Nijhuis, Christian A.; Qiu, Cheng–Wei; Yang, Joel K. W.

2014-01-01

371

Encapsulated Annealing: Enhancing the Plasmon Quality Factor in Lithographically-Defined Nanostructures  

NASA Astrophysics Data System (ADS)

Lithography provides the precision to pattern large arrays of metallic nanostructures with varying geometries, enabling systematic studies and discoveries of new phenomena in plasmonics. However, surface plasmon resonances experience more damping in lithographically-defined structures than in chemically-synthesized nanoparticles of comparable geometries. Grain boundaries, surface roughness, substrate effects, and adhesion layers have been reported as causes of plasmon damping, but it is difficult to isolate these effects. Using monochromated electron energy-loss spectroscopy (EELS) and numerical analysis, we demonstrate an experimental technique that allows the study of these effects individually, to significantly reduce the plasmon damping in lithographically-defined structures. We introduce a method of encapsulated annealing that preserves the shape of polycrystalline gold nanostructures, while their grain-boundary density is reduced. We demonstrate enhanced Q-factors in lithographically-defined nanostructures, with intrinsic damping that matches the theoretical Drude damping limit.

Bosman, Michel; Zhang, Lei; Duan, Huigao; Tan, Shu Fen; Nijhuis, Christian A.; Qiu, Cheng–Wei; Yang, Joel K. W.

2014-07-01

372

Thermoelectric properties by high temperature annealing  

NASA Technical Reports Server (NTRS)

The present invention generally provides methods of improving thermoelectric properties of alloys by subjecting them to one or more high temperature annealing steps, performed at temperatures at which the alloys exhibit a mixed solid/liquid phase, followed by cooling steps. For example, in one aspect, such a method of the invention can include subjecting an alloy sample to a temperature that is sufficiently elevated to cause partial melting of at least some of the grains. The sample can then be cooled so as to solidify the melted grain portions such that each solidified grain portion exhibits an average chemical composition, characterized by a relative concentration of elements forming the alloy, that is different than that of the remainder of the grain.

Ren, Zhifeng (Inventor); Chen, Gang (Inventor); Kumar, Shankar (Inventor); Lee, Hohyun (Inventor)

2009-01-01

373

Remediation tradeoffs addressed with simulated annealing optimization  

SciTech Connect

Escalation of groundwater remediation costs has encouraged both advances in optimization techniques to balance remediation objectives and economics and development of innovative technologies to expedite source region clean-ups. We present an optimization application building on a pump-and-treat model, yet assuming a prior removal of different portions of the source area to address the evolving management issue of more aggressive source remediation. Separate economic estimates of in-situ thermal remediation are combined with the economic estimates of the subsequent optimal pump-and-treat remediation to observe tradeoff relationships of cost vs. highest remaining contamination levels (hot spot). The simulated annealing algorithm calls the flow and transport model to evaluate the success of a proposed remediation scenario at a U.S.A. Superfund site contaminated with volatile organic compounds (VOCs).

Rogers, L. L., LLNL

1998-02-01

374

Annealing a Magnetic Cactus into Phyllotaxis  

E-print Network

The appearance of mathematical regularities in the disposition of leaves on a stem, scales on a pine-cone and spines on a cactus has puzzled scholars for millennia; similar so-called phyllotactic patterns are seen in self-organized growth, polypeptides, convection, magnetic flux lattices and ion beams. Levitov showed that a cylindrical lattice of repulsive particles can reproduce phyllotaxis under the (unproved) assumption that minimum of energy would be achieved by 2-D Bravais lattices. Here we provide experimental and numerical evidence that the Phyllotactic lattice is actually a ground state. When mechanically annealed, our experimental "magnetic cactus" precisely reproduces botanical phyllotaxis, along with domain boundaries (called transitions in Botany) between different phyllotactic patterns. We employ a structural genetic algorithm to explore the more general axially unconstrained case, which reveals multijugate (multiple spirals) as well as monojugate (single spiral) phyllotaxis.

Nisoli, Cristiano; Lammert, Paul E; Maynard, J D; Crespi, Vincent H

2010-01-01

375

Annealing a Magnetic Cactus into Phyllotaxis  

E-print Network

The appearance of mathematical regularities in the disposition of leaves on a stem, scales on a pine-cone and spines on a cactus has puzzled scholars for millennia; similar so-called phyllotactic patterns are seen in self-organized growth, polypeptides, convection, magnetic flux lattices and ion beams. Levitov showed that a cylindrical lattice of repulsive particles can reproduce phyllotaxis under the (unproved) assumption that minimum of energy would be achieved by 2-D Bravais lattices. Here we provide experimental and numerical evidence that the Phyllotactic lattice is actually a ground state. When mechanically annealed, our experimental "magnetic cactus" precisely reproduces botanical phyllotaxis, along with domain boundaries (called transitions in Botany) between different phyllotactic patterns. We employ a structural genetic algorithm to explore the more general axially unconstrained case, which reveals multijugate (multiple spirals) as well as monojugate (single spiral) phyllotaxis.

Cristiano Nisoli; Nathaniel M. Gabor; Paul E. Lammert; J. D. Maynard; Vincent H. Crespi

2010-02-03

376

Annealing a magnetic cactus into phyllotaxis  

NASA Astrophysics Data System (ADS)

The appearance of mathematical regularities in the disposition of leaves on a stem, scales on a pine-cone, and spines on a cactus has puzzled scholars for millennia; similar so-called phyllotactic patterns are seen in self-organized growth, polypeptides, convection, magnetic flux lattices and ion beams. Levitov showed that a cylindrical lattice of repulsive particles can reproduce phyllotaxis under the (unproved) assumption that minimum of energy would be achieved by two-dimensional Bravais lattices. Here we provide experimental and numerical evidence that the Phyllotactic lattice is actually a ground state. When mechanically annealed, our experimental “magnetic cactus” precisely reproduces botanical phyllotaxis, along with domain boundaries (called transitions in Botany) between different phyllotactic patterns. We employ a structural genetic algorithm to explore the more general axially unconstrained case, which reveals multijugate (multiple spirals) as well as monojugate (single-spiral) phyllotaxis.

Nisoli, Cristiano; Gabor, Nathaniel M.; Lammert, Paul E.; Maynard, J. D.; Crespi, Vincent H.

2010-04-01

377

Bit patterned media optimization at 1 Tdot/in2 by post-annealing  

NASA Astrophysics Data System (ADS)

We report on the fabrication of 1 Tdot/in2 bit patterned media with high coercivity (HC) and narrow intrinsic switching field distribution (iSFD) based on nanoimprint from a master pattern formed by e-beam guided block copolymer assembly onto a carbon hard mask and subsequent pattern transfer via etching into a thin CoCrPt perpendicular anisotropy recording layer. We demonstrate that an additional vacuum annealing step after pattern transfer into the CoCrPt layer and after Carbon hard mask removal not only yields recovery from undesired damage of the island edges, but actually transforms the islands into a magnetically more favorable compositional phase with higher HC, lower iSFD/HC, and three-fold increased thermal stability. Energy filtered transmission electron microscopy analysis reveals that the diffusion of Cr from the island cores to the periphery of the islands during post-annealing is responsible for the transformation of the magnetic bits into a more stable state.

Hellwig, Olav; Marinero, Ernesto E.; Kercher, Dan; Hennen, Tyler; McCallum, Andrew; Dobisz, Elizabeth; Wu, Tsai-Wei; Lille, Jeff; Hirano, Toshiki; Ruiz, Ricardo; Grobis, Michael K.; Weller, Dieter; Albrecht, Thomas R.

2014-09-01

378

Optical and paramagnetic properties of synthetic diamond crystals irradiated with electrons and annealed  

SciTech Connect

The optical and paramagnetic properties of single crystals of synthetic diamond grown by the temperature-gradient method in high-pressure apparatuses with the systems of catalytic solvents (Co, Fe) and (Ni, Fe) are studied at room temperature. The optical absorption spectra (in the wavelength range {lambda} = 400-800 nm) and the spectra of electron spin resonance are registered for the initial diamond crystals, the crystals irradiated with 6 MeV electrons (the fluence 1.5 x 10{sup 18} cm{sup -2}), and the irradiated diamonds subjected to isochronous thermal annealing in vacuum (for 60 min). It is shown that, with such treatment, the diamond crystals synthesized with different metal catalysts (Co or Ni) exhibit similar optical properties, but different paramagnetic properties. The data obtained by infrared spectroscopy and electron spin resonance spectroscopy are coincident for radiation defects and different for nitrogen centers (the P1 centers and exchange-coupled pairs of nitrogen atoms). The spectra of the electron spin resonance of the samples annealed at temperatures below 1273 K (in the case of the Co-containing catalyst) and 1073 K (in the case of Ni-containing catalyst) exhibited broad lines produced by residual impurities of the catalyst metal and were accompanied by a distortion of the spectrum of paramagnetic nitrogen in the form of a tilt of the ESR spectra with respect to the zero line.

Poklonski, N. A. [Belarusian State University (Belarus)], E-mail: poklonski@bsu.by; Gusakov, G. A. [Belarussian State University, Sevchenko Institute of Applied Physical Problems (Belarus); Bayev, V. G., E-mail: vadimbayev@tut.by; Lapchuk, N. M. [Belarusian State University (Belarus)

2009-05-15

379

Bit patterned media optimization at 1 Tdot/in{sup 2} by post-annealing  

SciTech Connect

We report on the fabrication of 1 Tdot/in{sup 2} bit patterned media with high coercivity (H{sub C}) and narrow intrinsic switching field distribution (iSFD) based on nanoimprint from a master pattern formed by e-beam guided block copolymer assembly onto a carbon hard mask and subsequent pattern transfer via etching into a thin CoCrPt perpendicular anisotropy recording layer. We demonstrate that an additional vacuum annealing step after pattern transfer into the CoCrPt layer and after Carbon hard mask removal not only yields recovery from undesired damage of the island edges, but actually transforms the islands into a magnetically more favorable compositional phase with higher H{sub C}, lower iSFD/H{sub C}, and three-fold increased thermal stability. Energy filtered transmission electron microscopy analysis reveals that the diffusion of Cr from the island cores to the periphery of the islands during post-annealing is responsible for the transformation of the magnetic bits into a more stable state.

Hellwig, Olav; Marinero, Ernesto E.; Kercher, Dan; Hennen, Tyler; McCallum, Andrew; Dobisz, Elizabeth; Wu, Tsai-Wei; Lille, Jeff; Hirano, Toshiki; Ruiz, Ricardo; Grobis, Michael K.; Weller, Dieter; Albrecht, Thomas R. [San Jose Research Center, HGST—A Western Digital Company, 3403 Yerba Buena Rd., San Jose, California 95135 (United States)

2014-09-28

380

Field emission behavior of carbon nanotube field emitters after high temperature thermal annealing  

SciTech Connect

The carbon nanotube (CNT) field emitters have been fabricated by attaching a CNT film on a graphite rod using graphite adhesive material. The CNT field emitters showed much improved field emission properties due to increasing crystallinity and decreasing defects in CNTs after the high temperature thermal annealing at 900 °C in vacuum ambient. The CNT field emitters showed the low turn-on electric field of 1.15 V/?m, the low threshold electric field of 1.62 V/?m, and the high emission current of 5.9 mA which corresponds to a current density of 8.5 A/cm{sup 2}. In addition, the CNT field emitters indicated the enhanced field emission properties due to the multi-stage effect when the length of the graphite rod increases. The CNT field emitter showed good field emission stability after the high temperature thermal annealing. The CNT field emitter revealed a focused electron beam spot without any focusing electrodes and also showed good field emission repeatability.

Sun, Yuning; Shin, Dong Hoon; Yun, Ki Nam; Leti, Guillaume [School of Electrical Engineering, Korea University, Seoul 136-713 (Korea, Republic of); Hwang, Yeon Mo; Song, Yenan [Department of Micro/Nano Systems, Korea University, Seoul 136-713 (Korea, Republic of); Jeon, Seok-Gy; Kim, Jung-Il [Advanced Medical Device Research Center, Korea Electrotechnology Research Institute (KERI), Ansan 127-56 (Korea, Republic of); Saito, Yahachi [Department of Quantum Engineering, Graduate School of Engineering, Nagoya University, Nagoya 464-8603 (Japan); Lee, Cheol Jin, E-mail: cjlee@korea.ac.kr [School of Electrical Engineering, Korea University, Seoul 136-713 (Korea, Republic of); Department of Micro/Nano Systems, Korea University, Seoul 136-713 (Korea, Republic of)

2014-07-15

381

Annealed Importance Sampling Reversible Jump MCMC algorithms  

SciTech Connect

It will soon be 20 years since reversible jump Markov chain Monte Carlo (RJ-MCMC) algorithms have been proposed. They have significantly extended the scope of Markov chain Monte Carlo simulation methods, offering the promise to be able to routinely tackle transdimensional sampling problems, as encountered in Bayesian model selection problems for example, in a principled and flexible fashion. Their practical efficient implementation, however, still remains a challenge. A particular difficulty encountered in practice is in the choice of the dimension matching variables (both their nature and their distribution) and the reversible transformations which allow one to define the one-to-one mappings underpinning the design of these algorithms. Indeed, even seemingly sensible choices can lead to algorithms with very poor performance. The focus of this paper is the development and performance evaluation of a method, annealed importance sampling RJ-MCMC (aisRJ), which addresses this problem by mitigating the sensitivity of RJ-MCMC algorithms to the aforementioned poor design. As we shall see the algorithm can be understood as being an “exact approximation” of an idealized MCMC algorithm that would sample from the model probabilities directly in a model selection set-up. Such an idealized algorithm may have good theoretical convergence properties, but typically cannot be implemented, and our algorithms can approximate the performance of such idealized algorithms to an arbitrary degree while not introducing any bias for any degree of approximation. Our approach combines the dimension matching ideas of RJ-MCMC with annealed importance sampling and its Markov chain Monte Carlo implementation. We illustrate the performance of the algorithm with numerical simulations which indicate that, although the approach may at first appear computationally involved, it is in fact competitive.

Karagiannis, Georgios; Andrieu, Christophe

2013-03-20

382

Solid-State Physical Phenomena and Effects Part III  

Microsoft Academic Search

This is the third in a series of four articles describing solid-state phenomena. Twelve solid-state phenomena and physical effects are provided. All of the twelve phenomena belong to a group which includes effects related to the dielectric properties of materials and transport phenomena for particles other than electrons or holes.

E. Scheibner

1962-01-01

383

Vacuum-sealed silicon micromachined pressure sensors  

Microsoft Academic Search

Considerable progress in silicon pressure sensors has been made in recent years. This paper discusses three types of vacuum-sealed silicon micromachined pressure sensors that represent the present state of the art in this important area. The devices are a capacitive vacuum sensor, a surface-micromachined microdiaphragm pressure sensor, and a resonant pressure sensor. Vacuum sealing for these devices is accomplished using

Masayoshi Esashi; Susumu Sugiyama; Kyoichi Ikeda; YUELIN WANG; Haruzo Miyashita

1998-01-01

384

REVIEW ARTICLE Vacuum Rabi splitting in semiconductors  

E-print Network

REVIEW ARTICLE Vacuum Rabi splitting in semiconductors The recent development of techniques. We discuss the recent results on vacuum Rabi splitting with a single quantum dot, emphasizing of a nanocavity. This review describes the history of realizing vacuum Rabi splitting (VRS) in the single-QD (SQD

Loss, Daniel

385

Utilize Vacuum Forming to Make Interdisciplinary Connections  

ERIC Educational Resources Information Center

The concept of vacuum forming has been around since the 19th century, despite not being fully utilized in industry until the 1950s. In the past, industrial arts classes have used vacuum-forming projects to concentrate solely on the manufacturing process and the final product. However, vacuum forming is not just an old industrial arts activity; it…

Love, Tyler S.; Valenza, Frank

2011-01-01

386

Simulated Annealing: A Monte Carlo Method for GPS Surveying  

E-print Network

annealing technique,which is a Monte Carlo method, to analyze and improve the e#ciency of the de­ signSimulated Annealing: A Monte Carlo Method for GPS Surveying Stefka Fidanova IPP -- BAS, Acad. G that uses a Monte Carlo global minimization technique for minimizing multi­variance functions [2

Fidanova, Stefka

387

Deformation and annealing response of TD-nickel chromium sheet  

NASA Technical Reports Server (NTRS)

The deformation and annealing response of TD-nickel chromium (TD-NiCr) 0.1 inch thick sheet was examined using various cold-rolling and annealing treatments. Upon annealing (above 816 C (1500 F), the as-received material was converted from an initially ultra-fine grain size (average grain dimension 0.51 micron) to a large grain structure. Increases in grain size by a factor of 100 to 200 were observed for this transformation. However, in those material states where the large grain transformation was absent, a fine grain recrystallized structure formed upon annealing (above 732 C (1350 F)). The deformation and annealing response of TD-NiCr sheet was evaluated with respect to the processing related variables as mode and severity of deformation and annealing temperature. Results indicate that the large grain transformation, classical primary recrystallization occurs. Using selected materials produced during the deformation and annealing study, the elevated temperature tensile properties of TD-NiCr sheet were examined in the temperature range 593 C (1100 F) to 1093 C (2000 F). It was observed that the elevated temperature tensile properties of TD-NiCr sheet could be optimized by the stabilization of a large grain size in this material using the cold working and/or annealing treatments developed during the present investigation.

Kane, R. D.; Ebert, L. J.

1973-01-01

388

Remote sensing of atmospheric duct parameters using simulated annealing  

NASA Astrophysics Data System (ADS)

Simulated annealing is one of the robust optimization schemes. Simulated annealing mimics the annealing process of the slow cooling of a heated metal to reach a stable minimum energy state. In this paper, we adopt simulated annealing to study the problem of the remote sensing of atmospheric duct parameters for two different geometries of propagation measurement. One is from a single emitter to an array of radio receivers (vertical measurements), and the other is from the radar clutter returns (horizontal measurements). Basic principles of simulated annealing and its applications to refractivity estimation are introduced. The performance of this method is validated using numerical experiments and field measurements collected at the East China Sea. The retrieved results demonstrate the feasibility of simulated annealing for near real-time atmospheric refractivity estimation. For comparison, the retrievals of the genetic algorithm are also presented. The comparisons indicate that the convergence speed of simulated annealing is faster than that of the genetic algorithm, while the anti-noise ability of the genetic algorithm is better than that of simulated annealing.

Zhao, Xiao-Feng; Huang, Si-Xun; Xiang, Jie; Shi, Wei-Lai

2011-09-01

389

STRIP TEMPERATURE IN A METAL COATING LINE ANNEALING FURNACE  

E-print Network

STRIP TEMPERATURE IN A METAL COATING LINE ANNEALING FURNACE Mark McGuinness1 and Stephen Taylor2 We continuously through the furnace, to certain temperatures and then cooling it, resulting in a change prior to being coated, by heating to a predeter- mined temperature for a definite time. Annealing

McGuinness, Mark

390

Time Fractional Formalism: Classical and Quantum Phenomena  

E-print Network

In this review, we present some fundamental classical and quantum phenomena in view of time fractional formalism. Time fractional formalism is a very useful tool in describing systems with memory and delay. We hope that this study can provide a deeper understanding of the physical interpretations of fractional derivative.

Hosein Nasrolahpour

2012-03-18

391

Velocity dependencies of some impact phenomena  

Microsoft Academic Search

A variety of cratering phenomena is discussed, primarily with respect to their dependencies on impact velocity. Based on experimental evidence, three impact regimes can be established, an elastic, a plastic, and a hydrodynamic regime. Within the hydrodynamic regime, the cartering process becomes uniform and independent of the impact velocity. It is mainly controlled by projectile and target densities and by

E. Schneider

1979-01-01

392

Towards Studying Transport Phenomena with Trapped Ions  

Microsoft Academic Search

Transport of charge and energy are key phenomena for many technological applications. The basic transport mechanisms, particularly in the quantum regime, offer rich physics. For instance, the conditions necessary for a fully quantum system to equilibrate are still under debate. We started an experimental effort to study energy transport in the quantum regime by placing single ions in microtraps formed

Michael Ramm; Thaned Pruttivarasin; Boyan Tabakov; Axel Kreuter; Nikos Daniilidis; Hartmut Häffner

2010-01-01

393

Simple Phenomena, Slow Motion, Surprising Physics  

ERIC Educational Resources Information Center

This article describes a few simple experiments that are worthwhile for slow motion recording and analysis either because of interesting phenomena that can be seen only when slowed down significantly or because of the ability to do precise time measurements. The experiments described in this article are quite commonly done in Czech schools. All…

Koupil, Jan; Vicha, Vladimir

2011-01-01

394

MIXING PHENOMENA IN INDUSTRIAL FUME AFTERBURNER SYSTEMS  

EPA Science Inventory

The report reviews the physical-mixing phenomena involved in the reactions that occur in afterburners or fume incinerators. It considers mixing in after-burners from three points of view. It first covers typical designs of afterburner components that are involved in the mixing ph...

395

University Students' Conceptions of Different Physical Phenomena  

Microsoft Academic Search

The purpose of this study was to examine how widespread university students' misconceptions of 3 physical phenomena were: namely, the motions of objects, seasonal changes, and aggregate changes of matter. One hundred and thirty-two university students completed a written questionnaire composed of 2 types of tasks. First, students evaluated the adequacy of a given explanation as compared to their knowledge

Eve Kikas

2003-01-01

396

Spooky Phenomena in Two-Photon Processes  

Microsoft Academic Search

A spooky phenomenon in two-photon coherent atomic absorption was discussed in 1980 [M. C. Li, Phys. Rev. A 22 (1980) 1323]. The absorption was initiated by two different laser sources. Classically, it is impossible for atoms to transit coherently in the absorption process, but quantum mechanically it is. This is one of the spooky phenomena in quantum mechanic. Around1990, there

Ming-Chiang Li

2006-01-01

397

Photo-Galvano-Mechanical Phenomena in Nanotubes  

E-print Network

Photo-Galvano-Mechanical Phenomena in Nanotubes Petr KraI\\ E. J. Mele2 , David Tomanek3 and Moshe elec- trical "ballistic current". The photo-currents can be generated even in centrosym- metric be also generated in semiconductor nanotubes or in higher bands of metallic nanotubes [2]. The photo

398

Beam coupling phenomena in fast kicker systems  

Microsoft Academic Search

Beam coupling phenomena have been observed in most fast kicker systems through out Brookhaven Collider-Accelerator complex. With ever-higher beam intensity, the signature of the beam becomes increasingly recognizable. The beam coupling at high intensity produced additional heat dissipation in high voltage modulator, thyratron grids and thyratron driver circuit sufficient to damage some components, and causes trigger instability. In this paper,

W. Zhang; L. A. Ahrens; J. Glenn; J. Sandberg; N. Tsoupas

2001-01-01

399

Finite element modeling of electromagnetic NDT phenomena  

Microsoft Academic Search

The development of computer-based defect characterization schemes for automated electromagnetic methods of nondestructive testing (NDT) requires adequate mathematical models to describe the complicated interactions of currents, fields and defects in materials. This paper describes the finite element equations governing active, residual and eddy current phenomena in materials with discontinuities and magnetic nonlinearity. It is suggested that the resulting magnetic vector

R. Palanisamy; W. Lord

1979-01-01

400

Gods, Heroes and Natural Phenomena Cosmologies  

Microsoft Academic Search

People have always been worried about the natural phenomena that have influenced their lives and the origin of these natural changes. That is why they have always tried to explain the creation of the world probably as a way to control it, protect them from it, or simply to understand it. It is always relevant to humankind to try to

Miguel Angel Alarcón

401

Interfacial phenomena and the ocular surface.  

PubMed

Ocular surface disorders, such as dry eye disease, ocular rosacea, and allergic conjunctivitis, are a heterogeneous group of diseases that require an interdisciplinary approach to establish underlying causes and develop effective therapeutic strategies. These diverse disorders share a common thread in that they involve direct changes in ocular surface chemistry as well as the rheological properties of the tear film and topographical attributes of the cellular elements of the ocular surface. Knowledge of these properties is crucial to understand the formation and stability of the preocular tear film. The study of interfacial phenomena of the ocular surface flourished during the 1970s and 1980s, but after a series of lively debates in the literature concerning distinctions between the epithelial and the glandular origin of ocular surface disorders during the 1990s, research into this important topic has declined. In the meantime, new tools and techniques for the characterization and functionalization of biological surfaces have been developed. This review summarizes the available literature regarding the physicochemical attributes of the ocular surface, analyzes the role of interfacial phenomena in the pathobiology of ocular surface disease, identifies critical knowledge gaps concerning interfacial phenomena of the ocular surface, and discusses the opportunities for the exploitation of these phenomena to develop improved therapeutics for the treatment of ocular surface disorders. PMID:24999101

Yañez-Soto, Bernardo; Mannis, Mark J; Schwab, Ivan R; Li, Jennifer Y; Leonard, Brian C; Abbott, Nicholas L; Murphy, Christopher J

2014-07-01

402

Exploratorium Exhibit and Phenomena Cross Reference  

NSDL National Science Digital Library

This alphabetical list of links explains a variety of scientific phenomena. Clicking on the name of a particular phenomenon will provide the user with a written definition or description and a list of links to exhibits (another part of the site) which illustrate it.

403

Theory of ultrafast phenomena in photoexcited semiconductors  

Microsoft Academic Search

The authors review the physics of ultrafast dynamics in semiconductors and their heterostructures, including both the observed experimental phenomena and the theoretical description of the processes. These are probed by ultrafast optical excitation, generating nonequilibrium states that can be monitored by time-resolved spectroscopy. Light pulses create coherent superpositions of states, and the dynamics of the associated phase relationships can be

Fausto Rossi; Tilmann Kuhn

2002-01-01

404

Numerical Simulation of Pulse Detonation Engine Phenomena  

Microsoft Academic Search

This paper describes one- and two-dimensional numerical simulations, with simplified as well as full reaction kinetics, of a single cycle pulse detonation engine (PDE). The present studies explore the igni- tion energies associated with the initiation of a det- onation in the PDE tube, and quantify reactive flow phenomena, performance parameters, and noise gen- eration associated with full and simplified

Xing He; Ann R. Karagozian

2003-01-01

405

New Strong-Field QED Effects at ELI: Nonperturbative Vacuum Pair Production  

E-print Network

Since the work of Sauter, and Heisenberg, Euler and K\\"ockel, it has been understood that vacuum polarization effects in quantum electrodynamics (QED) predict remarkable new phenomena such as light-light scattering and pair production from vacuum. However, these fundamental effects are difficult to probe experimentally because they are very weak, and they are difficult to analyze theoretically because they are highly nonlinear and/or nonperturbative. The Extreme Light Infrastructure (ELI) project offers the possibility of a new window into this largely unexplored world. I review these ideas, along with some new results, explaining why quantum field theorists are so interested in this rapidly developing field of laser science. I concentrate on the theoretical tools that have been developed to analyze nonperturbative vacuum pair production.

Gerald V. Dunne

2009-12-01

406

Evolution and Regularisation of Vacuum Brill Gravitational Waves in Spherical Polar Coordinates  

E-print Network

In this thesis the universal collapse of vacuum Brill waves is demonstrated numerically and analytically. This thesis presents the mathematical and numerical methods necessary to regularise and evolve Brill Gravitational Waves in spherical polar coordinates. A Cauchy ADM formulation is used for the time evolution. We find strong evidence that all IVP formulations of pure vacuum Brill gravitational waves collapse to form singularities/black holes, and we do not observe critical black hole mass scaling phenomena in the IVP parameter phase space that has been characterised in non-vacuum systems. A theoretical framework to prove this result analytically is presented. We discuss the meaning of Brill metric variables, the topology of trapped surfaces for various scenarios, and verify other results in the field related to critical values of initial value parameters and black hole formation approaching spatial infinity. The instability of Minkowski (flat) space under Brill wave and more general perturbations is demon...

Masterson, Andrew

2014-01-01

407

Measurement of the accumulation of water ice on optical components in cryogenic vacuum environments  

NASA Astrophysics Data System (ADS)

An experiment was performed to study and measure the deposition of water (H2O) ice on optical component surfaces under high-vacuum cryogenic conditions. Water was introduced into a cryogenic vacuum chamber via a hydrated molecular sieve zeolite housed in a valved external chamber, through an effusion cell, and impinged upon a quartz-crystal microbalance (QCM) and first-surface gold-plated mirror. A laser and photodiode setup external to the vacuum chamber monitored the multiple-beam interference reflectance of the ice-mirror configuration while the QCM measured the mass deposition. Data acquired and analyzed from this experiment indicate that water ice under these conditions accumulates on optical component surfaces as a thin film up to thicknesses over 45 microns and can be detected and measured by nonintrusive optical methods based upon multiple-beam interference phenomena. The QCM, a well-established measurement technique, was used to validate the interferometer.

Moeller, Trevor M.; Smith, L. Montgomery; Collins, Frank G.; Labello, Jesse M.; Rogers, James P.; Lowry, Heard S.; Crider, Dustin H.

2012-10-01

408

Decoherence delays false vacuum decay  

NASA Astrophysics Data System (ADS)

We show that gravitational interactions between massless thermal modes and a nucleating Coleman-de Luccia bubble may lead to efficient decoherence and strongly suppress metastable vacuum decay for bubbles that are small compared to the Hubble radius. The vacuum decay rate including gravity and thermal photon interactions has the exponential scaling \\Gamma \\sim \\Gamma _{CDL}^{2}, where ?CDL is the Coleman-de Luccia decay rate neglecting photon interactions. For the lowest metastable initial state an efficient quantum Zeno effect occurs due to thermal radiation of temperatures as low as the de Sitter temperature. This strong decoherence effect is a consequence of gravitational interactions with light external mode. We argue that efficient decoherence does not occur for the case of Hawking-Moss decay. This observation is consistent with requirements set by Poincaré recurrence in de Sitter space.

Bachlechner, Thomas C.

2013-05-01

409

Curved Space or Curved Vacuum?  

E-print Network

While the simple picture of a spatially flat, matter plus cosmological constant universe fits current observation of the accelerated expansion, strong consideration has also been given to models with dynamical vacuum energy. We examine the tradeoff of ``curving'' the vacuum but retaining spatial flatness, vs. curving space but retaining the cosmological constant. These different breakdowns in the simple picture could readily be distinguished by combined high accuracy supernovae and cosmic microwave background distance measurements. If we allow the uneasy situation of both breakdowns, the curvature can still be measured to 1%, but at the price of degrading estimation of the equation of state time variation by 60% or more, unless additional information (such as weak lensing data or a tight matter density prior) is included.

Eric V. Linder

2005-08-15

410

Vacuum outgassing of various materials  

SciTech Connect

A gas analytical system for measuring the evolved gases from materials during vacuum degassing is discussed. The outgassing data are based upon the throughput measurement and a computer-controlled quadrupole mass spectrometer allows the determination of residual gas species. A variety of materials have been tested in the as received condition at room temperature vacuum exposure. Test results are presented for materials such as chlorinated polyvinychloride (CPVC), low-density carbon foam and Monel knitted wire mesh (both of which could be used for the attenuation of electromagnetic or radio frequency interference), polyethylene (in the form of black pipe, sheet of various thicknesses, and as an electrostatically applied coating to metal substrates), as well as Parylene-N conformal coatings applied to CPVC, polyethylene, and stainless steel substrates.

Erikson, E.D.; Beat, T.G.; Berger, D.D.; Frazier, B.A.

1983-12-20

411

Vacuum outgassing of various materials  

SciTech Connect

A gas analytical system for measuring the evolved gases from materials during vacuum degassing is discussed. The outgassing data are based upon the throughput measurement and a computer-controlled quadrupole mass spectrometer allows the determination of residual gas species. A variety of materials have been tested in the ''as-received'' condition at room temperature vacuum exposure. Test results are presented for materials such as chlorinated polyvinylchloride (CPVC), low density carbon foam and Monel knitted wire mesh (both of which could be used for the attenuation of electromagnetic or radio frequency interference), polyethylene (in the form of black pipe, sheet of various thicknesses, and as an electrostatically applied coating to metal substrates), as well as Parylene-N/sup X/ conformal coatings applied to CPVC, polyethylene, and stainless steel substrates.

Erikson, E.D.; Beat, T.G.; Berger, D.D.; Frazier, B.A.

1984-04-01

412

Vacuum outgassing of various materials  

SciTech Connect

A gas analytical system for measuring the evolved gases from materials during vacuum degassing is discussed. The outgassing data are based upon the throughput measurement and a computer-controlled quadrupole mass spectrometer allows the determination of residual gas species. A variety of materials have been tested in the as received condition at room-temperature vacuum exposure. Test results are presented for some unusual materials such as chlorinated polyvinyl chloride (CPVC), low-density carbon foam and Monel knitted wire mesh (both of which could be used for the attenuation of electromagnetic or radio frequency interference), polyethylene (in the form of black pipe, various thicknesses of sheet, or as an electrostatically applied coating to metal substrates), as well as Parylene-N conformal coatings applied to either CPVC, polyethylene, or stainless steel substrates.

Erikson, E.D.; Beat, T.G.; Berger, D.D.; Frazier, B.A.

1983-09-28

413

Radiation Reaction in Quantum Vacuum  

E-print Network

From the development of the electron theory by H. A. Lorentz in 1906, many authors have tried to reformulate this model named "radiation reaction". P. A. M. Dirac derived the relativistic-classical electron model in 1938, which is now called the Lorentz-Abraham-Dirac model. But this model has the big difficulty of the run-away solution. Recently, this equation has become important for ultra-intense laser-electron (plasma) interactions. Therefore, it is desirable to stabilize this model of the radiation reaction for estimations. Via my recent research, I found a stabilized model of radiation reaction in quantum vacuum. This leads us to an updated Fletcher-Millikan's charge to mass ratio including radiation, de/dm, derived as the 4th order tensor measure. In this paper, I will discuss the latest update of the model and the ability of the equation of motion with radiation reaction in quantum vacuum via photon-photon scatterings.

Seto, Keita

2014-01-01

414

Radiation Reaction in Quantum Vacuum  

E-print Network

From the development of the electron theory by H. A. Lorentz in 1906, many authors have tried to reformulate this model named "radiation reaction". P. A. M. Dirac derived the relativistic-classical electron model in 1938, which is now called the Lorentz-Abraham-Dirac model. But this model has the big difficulty of the run-away solution. Recently, this equation has become important for ultra-intense laser-electron (plasma) interactions. Therefore, it is desirable to stabilize this model of the radiation reaction for estimations. Via my recent research, I found a stabilized model of radiation reaction in quantum vacuum. This leads us to an updated Fletcher-Millikan's charge to mass ratio including radiation, de/dm, derived as the 4th order tensor measure. In this paper, I will discuss the latest update of the model and the ability of the equation of motion with radiation reaction in quantum vacuum via photon-photon scatterings.

Keita Seto

2014-05-26

415

Infrared study on annealing effect on conformation of zinc stearate.  

PubMed

The molecular conformation and thermal transition behavior of two zinc stearate specimens, unannealed one and annealed one, were compared. The unannealed specimen has one thermal transition at 134 degrees C. Annealing was made by increasing temperature to 150 degrees C and cooling to room temperature slowly. This annealed specimen has an exothermic peak at 103 degrees C, and endothermic shoulders and a peak at 118, 124 and 131 degrees C, respectively. The observed frequencies of all bands of the unannealed specimen at room temperature are assigned to the all-trans conformation. We found new bands at 858, 823, 793, 766, 688, and 604 cm-1 for the annealed specimen. Based on the normal mode analyses, these bands are assigned to the TGT conformation at the COO end, where T means trans and G means gauche. The annealed specimen consists of almost all-trans molecule but partial molecules have the TGT conformation. PMID:16875870

Ishioka, Tsutomu; Kiritani, Atsushi; Kojima, Takuya

2007-04-01

416

Infrared study on annealing effect on conformation of zinc stearate  

NASA Astrophysics Data System (ADS)

The molecular conformation and thermal transition behavior of two zinc stearate specimens, unannealed one and annealed one, were compared. The unannealed specimen has one thermal transition at 134 °C. Annealing was made by increasing temperature to 150 °C and cooling to room temperature slowly. This annealed specimen has an exothermic peak at 103 °C, and endothermic shoulders and a peak at 118, 124 and 131 °C, respectively. The observed frequencies of all bands of the unannealed specimen at room temperature are assigned to the all-trans conformation. We found new bands at 858, 823, 793, 766, 688, and 604 cm -1 for the annealed specimen. Based on the normal mode analyses, these bands are assigned to the TGT conformation at the COO end, where T means trans and G means gauche. The annealed specimen consists of almost all-trans molecule but partial molecules have the TGT conformation.

Ishioka, Tsutomu; Kiritani, Atsushi; Kojima, Takuya

2007-04-01

417

Cold cathode vacuum discharge tube  

DOEpatents

A cold cathode vacuum discharge tube, and method for making same, with an interior surface of the trigger probe coated with carbon deposited by carbon vapor deposition (CVD) or diamond-like carbon (DLC) deposition. Preferably a solid graphite insert is employed in the probe-cathode structure in place of an aluminum bushing employed in the prior art. The CVD or DLC probe face is laser scribed to allow resistance trimming to match available trigger voltage signals and to reduce electrical aging.

Boettcher, Gordon E. (Albuquerque, NM)

1998-01-01

418

Quantum vacuum and accelerated expansion  

E-print Network

A new approach to extraction of quantum vacuum energy, in the context of the accelerated expansion, is proposed, and it is shown that experimentally realistic orders of values can be derived. The idea has been implemented in the framework of the Friedmann-Lemaitre-Robertson-Walker geometry in the language of the effective action in the relativistic formalism of Schwinger's proper time and Seeley-DeWitt's heat kernel expansion.

Bogus?aw Broda; Micha? Szanecki

2008-12-29

419

Inflation in a Symmetric Vacuum  

E-print Network

If in a finite universe, the tree-level vacuum is a symmetric superposition of coherent states, in each of which the inflaton field assumes a different, energy-minimizing mean value (vev), then the resulting energy is positive and decreases exponentially as the volume of the universe increases. This effect can drive inflation when that volume is small and explain part of dark energy when it is big, but the effect is exceedingly tiny except at very early times.

Kevin Cahill

2007-05-23

420

Improved Aerogel Vacuum Thermal Insulation  

NASA Technical Reports Server (NTRS)

An improved design concept for aerogel vacuum thermal-insulation panels calls for multiple layers of aerogel sandwiched between layers of aluminized Mylar (or equivalent) poly(ethylene terephthalate), as depicted in the figure. This concept is applicable to both the rigid (brick) form and the flexible (blanket) form of aerogel vacuum thermal-insulation panels. Heretofore, the fabrication of a typical aerogel vacuum insulating panel has involved encapsulation of a single layer of aerogel in poly(ethylene terephthalate) and pumping of gases out of the aerogel-filled volume. A multilayer panel according to the improved design concept is fabricated in basically the same way: Multiple alternating layers of aerogel and aluminized poly(ethylene terephthalate) are assembled, then encapsulated in an outer layer of poly(ethylene terephthalate), and then the volume containing the multilayer structure is evacuated as in the single-layer case. The multilayer concept makes it possible to reduce effective thermal conductivity of a panel below that of a comparable single-layer panel, without adding weight or incurring other performance penalties. Implementation of the multilayer concept is simple and relatively inexpensive, involving only a few additional fabrication steps to assemble the multiple layers prior to evacuation. For a panel of the blanket type, the multilayer concept, affords the additional advantage of reduced stiffness.

Ruemmele, Warren P.; Bue, Grant C.

2009-01-01

421

Vacuum pyrolysis of used tires  

SciTech Connect

The vacuum pyrolysis of used tires enables the recovery of useful products, such as pyrolytic oil and pyrolytic carbon black (CB{sub P}). The light part of the pyrolytic oil contains dl-limonene which has a high price on the market. The naphtha fraction can be used as a high octane number component for gasoline. The middle distillate demonstrated mechanical and lubricating properties similar to those of the commercial aromatic oil Dutrex R 729. The heavy oil was tested as a feedstock for the production of needle coke. It was found that the surface morphology of CB{sub P} produced by vacuum pyrolysis resembles that of commercial carbon black. The CB{sub P} contains a higher concentration of inorganic compounds (especially ZnO and S) than commercial carbon black. The pyrolysis process feasibility looks promising. One old tire can generate upon vacuum pyrolysis, incomes of at least $2.25 US with a potential of up to $4.83 US/tire upon further product improvement. The process has been licensed to McDermott Marketing Servicing Inc. (Houston) for its exploitation in the US.

Roy, C.; Darmstadt, H.; Benallal, B.; Chaala, A.; Schwerdtfeger, A.E. [Univ. Laval, Quebec City, Quebec (Canada). Dept. de Geneie Chimique

1995-11-01

422

Running Jobs in the Vacuum  

NASA Astrophysics Data System (ADS)

We present a model for the operation of computing nodes at a site using Virtual Machines (VMs), in which VMs are created and contextualized for experiments by the site itself. For the experiment, these VMs appear to be produced spontaneously "in the vacuum" rather having to ask the site to create each one. This model takes advantage of the existing pilot job frameworks adopted by many experiments. In the Vacuum model, the contextualization process starts a job agent within the VM and real jobs are fetched from the central task queue as normal. An implementation of the Vacuum scheme, Vac, is presented in which a VM factory runs on each physical worker node to create and contextualize its set of VMs. With this system, each node's VM factory can decide which experiments' VMs to run, based on site-wide target shares and on a peer-to-peer protocol in which the site's VM factories query each other to discover which VM types they are running. A property of this system is that there is no gate keeper service, head node, or batch system accepting and then directing jobs to particular worker nodes, avoiding several central points of failure. Finally, we describe tests of the Vac system using jobs from the central LHCb task queue, using the same contextualization procedure for VMs developed by LHCb for Clouds.

McNab, A.; Stagni, F.; Ubeda Garcia, M.

2014-06-01

423

Rotary bayonets for cryogenic and vacuum service  

SciTech Connect

Rotary bayonets were designed, tested, and installed for liquid nitrogen, liquid argon, and vacuum service. This paper will present the design, testing, and service record for two sizes of vacuum jacketed cryogenic rotary bayonets and two sizes of vacuum service rotary bayonets. Materials used in construction provide electrical isolation across the bayonet joint. The joint permits 360 degrees of rotation between the male and female pipe sections while maintaining integrity of service. Assemblies using three such joints were built to allow end connection points to be translated through at least 1 meter of horizontal travel while kept in service. Vacuum jacketed sizes built in-house at Fermi National Accelerator Laboratory are 1-1/2 in. inner pipe size, 3 in. vacuum jacket, and 4 in. inner pipe size, 6 in. vacuum jacket The single wall vacuum service bayonets are in 4 in. and 6 in. pipe sizes. The bayonets have successfully been in active service for over one year.

Rucinski, R.A.; Dixon, K.D.; Krasa, R.; Krempetz, K.J.; Mulholland, G.T.; Trotter, G.R.; Urbin, J.B.

1993-07-01

424

Vacuum-Packaging Technology for IRFPAs  

NASA Astrophysics Data System (ADS)

We developed vacuum-packaging equipment and low-cost vacuum packaging technology for IRFPAs. The equipment is versatile and can process packages with various materials and structures. Getters are activated before vacuum packaging, and we can solder caps/ceramic-packages and caps/windows in a high-vacuum condition using this equipment. We also developed a micro-vacuum gauge to measure pressure in vacuum packages. The micro-vacuum gauge uses the principle of thermal conduction of gases. We use a multi-ceramic package that consists of six packages fabricated on a ceramic sheet, and confirm that the pressure in the processed packages is sufficiently low for high-performance IRFPA.

Matsumura, Takeshi; Tokuda, Takayuki; Tsutinaga, Akinobu; Kimata, Masafumi; Abe, Hideyuki; Tokashiki, Naotaka

425

Vacuum Energy and Inflation: 2. A Vacuum Energy Universe  

NASA Astrophysics Data System (ADS)

In most of our undergraduate physics courses, we study what can happen in space, but space itself plays a passive role. In basic cosmology, the opposite is true. It is the behavior of space that plays the major role. In this, paper #2, we first discuss the nature of a simple expanding space, and then look at the consequence of applying Newton's law of gravity in this space. The calculations are particularly simple if most of the energy behaves like the vacuum energy discussed earlier in paper #1. The calculation is easy but the results are spectacular.

Huggins, Elisha

2013-10-01

426

Microplasma generation in a microscale short vacuum arc  

SciTech Connect

A mechanism of plasma plume generation and plasma jet formation in a microscale vacuum arc (MVA) was proposed. The uniqueness of the subject is the force generated by a common plasma plume extracted from cathode and anode spots in a MVA. A calculating model for microplasma origin was developed taking into account the atom ionization and the phenomena in the nonequilibrium layers near evaporated surface in the cathode and anode regions. The plasma parameters as well as the electrode erosion rate were studied. It was found relatively large anode erosion rate and force at the anode surface in MVA in comparison to the force that usually occurs at the cathode in arcs with large gap. This important result of MVA was proposed to use in an exceptional microthruster concept for spacecraft propulsion and for anode microplasma source.

Beilis, Isak I. [Electrical Discharge and Plasma Laboratory, School of Electrical Engineering, Fleischman Faculty of Engineering, Tel Aviv University, P.O. Box 39040, Tel Aviv 69978 (Israel)

2008-03-24

427

Microplasma generation in a microscale short vacuum arc  

NASA Astrophysics Data System (ADS)

A mechanism of plasma plume generation and plasma jet formation in a microscale vacuum arc (MVA) was proposed. The uniqueness of the subject is the force generated by a common plasma plume extracted from cathode and anode spots in a MVA. A calculating model for microplasma origin was developed taking into account the atom ionization and the phenomena in the nonequilibrium layers near evaporated surface in the cathode and anode regions. The plasma parameters as well as the electrode erosion rate were studied. It was found relatively large anode erosion rate and force at the anode surface in MVA in comparison to the force that usually occurs at the cathode in arcs with large gap. This important result of MVA was proposed to use in an exceptional microthruster concept for spacecraft propulsion and for anode microplasma source.

Beilis, Isak I.

2008-03-01

428

Kinetically controlled phenomena in dynamic combinatorial libraries.  

PubMed

Dynamic combinatorial libraries (DCLs) are collections of structurally related compounds that can interconvert through reversible chemical reaction(s). Such reversibility endows DCLs with adaptability to external stimuli, as rapid interconversion allows quick expression of those DCL components which best respond to the disturbing stimulus. This Tutorial Review focuses on the kinetically controlled phenomena that occur within DCLs. Specifically, it will describe dynamic chiral resolution of DCLs, their self-sorting under the influence of irreversible chemical and physical stimuli, and the autocatalytic behaviours within DCLs which can result in self-replicating systems. A brief discussion of precipitation-induced phenomena will follow and the review will conclude with the presentation of covalent organic frameworks (COFs)-porous materials whose synthesis critically depends on the fine tuning of the crystal growth and error correction rates within large DCLs. PMID:24445841

Ji, Qing; Lirag, Rio Carlo; Miljani?, Ognjen Š

2014-03-21

429

A review of impulsive phase phenomena  

NASA Technical Reports Server (NTRS)

A brief review is given of impulsive phase phenomena in support of the models used to compute the energies of the different components of the flares under study. The observational characteristics of the impulsive phase are discussed as well as the evidence for multi-thermal or non-thermal phenomena. The significance of time delays between hard X-rays and microwaves is discussed in terms of electron beams and Alfven waves, two-step acceleration, and secondary bursts at large distances from the primary source. Observations indicating the occurrence of chromospheric evaporation, coronal explosions, and thermal conduction fronts are reviewed briefly, followed by the gamma ray and neutron results. Finally, a preferred flare scenario and energy source are presented involving the interactions in a complex of magnetic loops with the consequent reconnection and electron acceleration.

Dejager, C.

1986-01-01

430

Probabilistic Dynamic Logic of Phenomena and Cognition  

E-print Network

The purpose of this paper is to develop further the main concepts of Phenomena Dynamic Logic (P-DL) and Cognitive Dynamic Logic (C-DL), presented in the previous paper. The specific character of these logics is in matching vagueness or fuzziness of similarity measures to the uncertainty of models. These logics are based on the following fundamental notions: generality relation, uncertainty relation, simplicity relation, similarity maximization problem with empirical content and enhancement (learning) operator. We develop these notions in terms of logic and probability and developed a Probabilistic Dynamic Logic of Phenomena and Cognition (P-DL-PC) that relates to the scope of probabilistic models of brain. In our research the effectiveness of suggested formalization is demonstrated by approximation of the expert model of breast cancer diagnostic decisions. The P-DL-PC logic was previously successfully applied to solving many practical tasks and also for modelling of some cognitive processes.

Vityaev, Evgenii; Perlovsky, Leonid; Smerdov, Stanislav

2011-01-01

431

Transport Phenomena During Equiaxed Solidification of Alloys  

NASA Technical Reports Server (NTRS)

Recent progress in modeling of transport phenomena during dendritic alloy solidification is reviewed. Starting from the basic theorems of volume averaging, a general multiphase modeling framework is outlined. This framework allows for the incorporation of a variety of microscale phenomena in the macroscopic transport equations. For the case of diffusion dominated solidification, a simplified set of model equations is examined in detail and validated through comparisons with numerous experimental data for both columnar and equiaxed dendritic growth. This provides a critical assessment of the various model assumptions. Models that include melt flow and solid phase transport are also discussed, although their validation is still at an early stage. Several numerical results are presented that illustrate some of the profound effects of convective transport on the final compositional and structural characteristics of a solidified part. Important issues that deserve continuing attention are identified.

Beckermann, C.; deGroh, H. C., III

1997-01-01

432

Natural phenomena hazards site characterization criteria  

SciTech Connect

The criteria and recommendations in this standard shall apply to site characterization for the purpose of mitigating Natural Phenomena Hazards (wind, floods, landslide, earthquake, volcano, etc.) in all DOE facilities covered by DOE Order 5480.28. Criteria for site characterization not related to NPH are not included unless necessary for clarification. General and detailed site characterization requirements are provided in areas of meteorology, hydrology, geology, seismology, and geotechnical studies.

Not Available

1994-03-01

433

Side writing phenomena in narrow track recording  

Microsoft Academic Search

Edge writing phenomena in narrow track recording on both well-oriented and planar isotropic thin-film recording media are studied by numerical micromagnetic modeling. Multiple dibit transition pairs are simulated and statistical properties are analyzed. The magnetization patterns of the simulated dibits are studied as well as the magnetic pole density distributions. It is found that, for the well-oriented film, the magnetic

Jian-Gang Zhu; Xiao-Guang Ye; T. C. Arnoldussen

1992-01-01

434

Search for collective phenomena in hadron interactions  

SciTech Connect

New results of the search for collective phenomena have been obtained and analyzed in the present report. The experimental studies are carried out on U-70 accelerator of IHEP in Protvino. It is suggested that these phenomena can be discovered at the energy range of 50-70 GeV in the extreme multiplicity region since the high-density matter can form in this very region. The collective behavior of secondary particles is considered to manifest itself in the Bose-Einstein condensation of pions, Vavilov-Cherenkov gluon radiation, excess of soft-photon yield, and other unique phenomena. The perceptible peak in the angular distribution has been revealed. It was interpreted as the gluon radiation and so the parton matter refraction index was determined. The new software was designed for the track reconstruction based on Kalman Filter technique. This algorithm allows one to estimate more precisely the track parameters (especially momentum). The search for Bose-Einstein condensation can be continued by using the selected events with the multiplicity of more than eight charged particles. The gluon dominance model predictions have shown good agreement with the multiplicity distribution at high multiplicity and confirmed the guark-gluon medium formation under these conditions.

Kokoulina, E. S., E-mail: kokoulin@sunse.jinr.ru; Nikitin, V. A., E-mail: nikitin@sunse.jinr.ru; Petukhov, Y. P., E-mail: Yuri.Petukhov@ihep.r [LHEP, JINR (Russian Federation); Karpov, A. V., E-mail: karpov@dm.komisc.ru; Kutov, A. Ya., E-mail: kutov@dm.komisc.r [Komi SC UrD RAS, Department of Mathematics (Russian Federation)

2010-12-15

435

Physical mechanism of membrane osmotic phenomena  

SciTech Connect

The microscale, physicomechanical cause of osmosis and osmotic pressure in systems involving permeable and semipermeable membranes is not well understood, and no fully satisfactory mechanism has been offered to explain these phenomena. A general theory, albeit limited to dilute systems of inert, noninteracting solute particles, is presented which demonstrates that short-range forces exerted by the membrane on the dispersed solute particles constitute the origin of osmotic phenomena. At equilibrium, the greater total force exerted by the membrane on those solute particles present in the reservoir containing the more concentrated of the two solutions bathing the membrane is balanced by a macroscopically observable pressure difference between the two reservoirs. The latter constitutes the so-called osmotic pressure difference. Under nonequilibrium conditions, the membrane-solute force is transmitted to the solvent, thus driving the convective flow of solvent observed macroscopically as osmosis. While elements of these ideas have been proposed previously in various forms, the general demonstration offered here of the physicomechanical source of osmotic phenomena is novel. Beyond the purely academic interest that exists in establishing a mechanical understanding of osmotic pressure, the analysis lays the foundation underlying a quantitative theory of osmosis in dilute, nonequilibrium systems outlined in a companion paper.

Guell, D.C. [Los Alamos National Lab., NM (United States)] [Los Alamos National Lab., NM (United States); Brenner, H. [Massachusetts Inst. of Tech., Cambridge, MA (United States). Dept. of Chemical Engineering] [Massachusetts Inst. of Tech., Cambridge, MA (United States). Dept. of Chemical Engineering

1996-09-01

436

Evaporation phenomena in f(T) gravity  

E-print Network

We formulate evaporation phenomena in a generic model of generalized teleparallel gravity in Weitzenbock spacetime with diagonal and non-diagonal tetrads basis. We also perform the perturbation analysis around the constant torsion scalar solution named Nariai spacetime which is an exact solution of field equations as the limiting case of the Schwarzschild-de Sitter and in the limit where two back hole and their cosmological horizons coincide. By a carefully analysis of the horizon perturbation equation, we show that (anti)evaporation can not happen if we use a diagonal tetrad basis. This result implies that a typical black hole in any generic form of generalized teleparallel gravity is frozen in its initial state if we use the diagonal tetrads. But in the case of non-diagonal tetrads the analysis is completely different. By a suitable non trivial non-diagonal tetrad basis we investigate the linear stability of the model under perturbations of the metric and torsion simultaneously. We observe that in spite of the diagonal case, both evaporation and anti evaporation can happen. The phenomena depend on the initial phase of the horizon perturbation. In the first mode when we restrict ourselves to the first lower modes the (anti)evaporation happens. So, in non-diagonal case the physical phenomena is reasonable. This is an important advantage of using non-diagonal tetrads instead of the diagonal ones. We also see that this is an universal feature, completely independent from the form of the model.

M. J. S. Houndjo; D. Momeni; R. Myrzakulov; M. E. Rodrigues

2013-05-08

437

Characterization of annealing in polycrystalline copper using harmonic generation technique  

NASA Astrophysics Data System (ADS)

Sensitivity of nonlinear ultrasonic method towards isothermal annealing in pure copper is investigated in this study. It was reported that, recovery, recrystallization and grain growth associated with annealing has profound influence on nonlinearity parameter. Presence of precipitates and secondary phase particles, and its effect on nonlinearity parameter was considered by many authors. However, in this study, focus is on the influence of grain-growth on nonlinearity parameter. Variation of non-linearity parameter, ?, with different holding durations were analyzed. All the samples were annealed at a temperature above its recrystallization temperature. Further, metallography studies as well as hardness measurements were performed to understand the relationship between microstructural changes and ultrasonic nonlinearity parameter.

Mini, R. S.; Balasubramaniam, Krishnan; Ravindran, Parag

2014-02-01

438

Laser annealing of implanted silicon carbide and Raman characterization  

NASA Astrophysics Data System (ADS)

Pulsed-laser-based methods have been applied for post-implant annealing of p-type Al doped 4H-SiC wafers in order to restore the crystal structure and to electrically activate the doping species. The annealing was performed with the second (532nm) and third (355nm) harmonic of a Nd:YAG laser at 4ns pulse duration. The epilayers were characterized by micro-Raman spectroscopy under surface and cross sectional backscattering. Changes in the phonon mode-intensity were related to the laser annealing induced recrystallization of the implanted material. The results were compared with changes in the infrared reflectivity across the Restsrahlen band.

Zergioti, I.; Kontos, A. G.; Zekentes, K.; Boutopoulos, C.; Terzis, P.; Raptis, Y. S.

2006-05-01

439

Graphene preparation by annealing of Co/SiC structure  

NASA Astrophysics Data System (ADS)

This work is focused on graphene preparation using the segregation method with Co/SiC structure, the method being a viable low temperature synthesis approach. The graphene preparation was carried out with the cobalt layer of 300 nm thickness; the technological process is based on an optimization of parameters (temperature and duration) of annealing which is a crucial step of the synthesis. 850 °C as an annealing temperature and 10 s as an annealing duration have been found to be the most optimal. The prepared graphene is close to the bi-layer graphene structure with its parameters. Structural parameters of the prepared graphene were determined from spectra obtained by Raman spectroscopy.

Machá?, Petr; Cicho?, Stanislav; Mišková, Linda; Vondrá?ek, Martin

2014-11-01

440

Vacuum friction in rotating particles  

E-print Network

We study the frictional torque acting on particles rotating in empty space. At zero temperature, vacuum friction transforms mechanical energy into light emission and produces particle heating. However, particle cooling relative to the environment occurs at finite temperatures and low rotation velocities. Radiation emission is boosted and its spectrum significantly departed from a hot-body emission profile as the velocity increases. Stopping times ranging from hours to billions of years are predicted for materials, particle sizes, and temperatures accessible to experiment. Implications for the behavior of cosmic dust are discussed.

A. Manjavacas; F. J. García de Abajo

2010-09-21

441

Cold cathode vacuum discharge tube  

DOEpatents

A cold cathode vacuum discharge tube, and method for making same, with an interior surface of the trigger probe coated with carbon deposited by chemical vapor deposition (CVD) or diamond-like carbon (DLC) deposition are disclosed. Preferably a solid graphite insert is employed in the probe-cathode structure in place of an aluminum bushing employed in the prior art. The CVD or DLC probe face is laser scribed to allow resistance trimming to match available trigger voltage signals and to reduce electrical aging. 14 figs.

Boettcher, G.E.

1998-04-14

442

Laser-triggered vacuum switch  

DOEpatents

A laser-triggered vacuum switch has a material such as a alkali metal halide on the cathode electrode for thermally activated field emission of electrons and ions upon interaction with a laser beam, the material being in contact with the cathode with a surface facing the discharge gap. The material is preferably a mixture of KCl and Ti powders. The laser may either shine directly on the material, preferably through a hole in the anode, or be directed to the material over a fiber optic cable.

Brannon, Paul J. (Albuquerque, NM); Cowgill, Donald F. (Danville, CA)

1990-01-01

443

Cold cathode vacuum discharge tube  

DOEpatents

A cold cathode vacuum discharge tube, and method for making same, are disclosed with an interior surface of the trigger probe coated with carbon deposited by carbon vapor deposition (CVD) or diamond-like carbon (DLC) deposition. Preferably a solid graphite insert is employed in the probe-cathode structure in place of an aluminum bushing employed in the prior art. The CVD or DLC probe face is laser scribed to allow resistance trimming to match available trigger voltage signals and to reduce electrical aging. 15 figs.

Boettcher, G.E.

1998-03-10

444

Shielding vacuum fluctuations with graphene  

E-print Network

The Casimir-Polder interaction of ground-state and excited atoms with graphene is investigated with the aim to establish whether graphene systems can be used as a shield for vacuum fluctuations of an underlying substrate. We calculate the zero-temperature Casimir-Polder potential from the reflection coefficients of graphene within the framework of the Dirac model. For both doped and undoped graphene we show limits at which graphene could be used effectively as a shield. Additional results are given for AB-stacked bilayer graphene.

Sofia Ribeiro; Stefan Scheel

2014-03-14

445

Vacuum Friction in Rotating Particles  

SciTech Connect

We study the frictional torque acting on particles rotating in empty space. At zero temperature, vacuum friction transforms mechanical energy into light emission and produces particle heating. However, particle cooling relative to the environment occurs at finite temperatures and low rotation velocities. Radiation emission is boosted and its spectrum significantly departed from a hot-body emission profile as the velocity increases. Stopping times ranging from hours to billions of years are predicted for materials, particle sizes, and temperatures accessible to experiment. Implications for the behavior of cosmic dust are discussed.

Manjavacas, A.; Garcia de Abajo, F. J. [Instituto de Optica--CSIC, Serrano 121, 28006 Madrid (Spain)

2010-09-10

446

MSW Effects in Vacuum Oscillations  

SciTech Connect

We point out that for solar neutrino oscillations with the mass-squared difference of Delta m^2 ~;; 10^-10 - 10^-9 eV^2, traditionally known as"vacuum oscillation'' range, the solar matter effects are non-negligible, particularly for the low energy pp neutrinos. One consequence of this is that the values of the mixing angle theta and pi/2-theta are not equivalent, leading to the need to consider the entire physical range of the mixing angle 0<=theta<=pi/2 when determining the allowed values of the neutrino oscillation parameters.

Friedland, Alexander

2000-02-06

447

Superluminal propagation of squeezed vacuum  

E-print Network

We experimentally demonstrate the superluminal propagation of modulated quadrature squeezed vacuum optical field, generated via the polarization self-rotation (PSR) effect. We observed the advancement of the signal propagating through a resonant Rb vapor with negative dispersion due to Zeeman coherence. The measured advancement grew linearly with atomic density, reaching a maximum of $11 \\pm 1 \\mu$s, which corresponded to a negative group velocity of $v_g\\approx - 7,000 $ m/s. We also confirmed that the increasing advancement was accompanied by a reduction of output squeezing levels due to optical losses, in good agreement with theoretical predictions.

Romanov, Gleb; Novikova, Irina; Mikhailov, Eugeniy E

2014-01-01

448

The RNA annealing mechanism of the HIV-1 Tat peptide: conversion of the RNA into an annealing-competent conformation  

PubMed Central

The annealing of nucleic acids to (partly) complementary RNA or DNA strands is involved in important cellular processes. A variety of proteins have been shown to accelerate RNA/RNA annealing but their mode of action is still mainly uncertain. In order to study the mechanism of protein-facilitated acceleration of annealing we selected a short peptide, HIV-1 Tat(44–61), which accelerates the reaction efficiently. The activity of the peptide is strongly regulated by mono- and divalent cations which hints at the importance of electrostatic interactions between RNA and peptide. Mutagenesis of the peptide illustrated the dominant role of positively charged amino acids in RNA annealing—both the overall charge of the molecule and a precise distribution of basic amino acids within the peptide are important. Additionally, we found that Tat(44–61) drives the RNA annealing reaction via entropic rather than enthalpic terms. One-dimensional-NMR data suggest that the peptide changes the population distribution of possible RNA structures to favor an annealing-prone RNA conformation, thereby increasing the fraction of colliding RNA molecules that successfully anneal. PMID:21297117

Doetsch, Martina; Fürtig, Boris; Gstrein, Thomas; Stampfl, Sabine; Schroeder, Renée

2011-01-01

449

Measurement of the accumulation of water ice on optical components in cryogenic vacuum environments  

NASA Astrophysics Data System (ADS)

Standard vacuum practices mitigate the presence of water vapor and contamination inside cryogenic vacuum chambers. However, anomalies can occur in the facility that can cause the accumulation of amorphous water ice on optics and test articles. Under certain conditions, the amorphous ice on optical components shatters, which leads to a reduction in signal or failure of the component. An experiment was performed to study and measure the deposition of water (H2O) ice on optical surfaces under high-vacuum cryogenic conditions. Water was introduced into a cryogenic vacuum chamber, via a hydrated molecular sieve zeolite, through an effusion cell and impinged upon a quartz-crystal microbalance (QCM) and first-surface gold-plated mirror. A laser and photodiode setup, external to the vacuum chamber, monitored the multiple-beam interference reflectance of the ice-mirror configuration while the QCM measured the mass deposition. Data indicates that water ice, under these conditions, accumulates as a thin film on optical surfaces to thicknesses over 45 microns and can be detected and measured by nonintrusive optical methods which are based upon multiple-beam interference phenomena. The QCM validated the interference measurements. This experiment established proof-of-concept for a miniature system for monitoring ice accumulation within the chamber.

Moeller, Trevor M.; Montgomery Smith, L.; Collins, Frank G.; Labello, Jesse M.; Rogers, James P.; Lowry, Heard S.; Crider, Dustin H.

2012-11-01

450

Architecture and operation of the Z Pulsed Power Facility vacuum system.  

SciTech Connect

The Z Pulsed Power Facility at Sandia National Laboratories in Albuquerque, New Mexico, USA is one of the world's premier high energy density physics facilities. The Z Facility derives its name from the z-pinch phenomena which is a type of plasma confinement system that uses the electrical current in the plasma to generate a magnetic field that compresses it. Z refers to the direction of current flow, the z axis in a three dimensional Cartesian coordinate system. The multiterawatt, multimegajoule electrical pulse the Facility produces is 100-400 nanoseconds in time. Research and development programs currently being conducted on the Z Facility include inertial confinement fusion, dynamic material properties, laboratory astrophysics and radiation effects. The Z Facility vacuum system consists of two subsystems, center section and load diagnostics. Dry roughing pumps and cryogenic high vacuum pumps are used to evacuate the 40,000 liter, 200 square meter center section of the facility where the experimental load is located. Pumping times on the order of two hours are required to reduce the pressure from atmospheric to 10{sup -5} Torr. The center section is cycled from atmosphere to high vacuum for each experiment. The facility is capable of conducting one to two experiments per day. Numerous smaller vacuum pumping systems are used to evacuate load diagnostics. The megajoules of energy released during an experiment causes damage to the Facility that presents numerous challenges for reliable operation of the vacuum system.

Riddle, Allen Chauncey; Petmecky, Don; Weed, John Woodruff

2010-11-01

451

Vacuum Attachment for XRF Scanner  

NASA Technical Reports Server (NTRS)

Vacuum apparatuses have been developed for increasing the range of elements that can be identified by use of x-ray fluorescent (XRF) scanners of the type mentioned in the two immediately preceding articles. As a consequence of the underlying physical principles, in the presence of air, such an XRF scanner is limited to analysis of chlorine and elements of greater atomic number. When the XRF scanner is operated in a vacuum, it extends the range of analysis to lower atomic numbers - even as far as aluminum and sodium. Hence, more elements will be available for use in XRF labeling of objects as discussed in the two preceding articles. The added benefits of the extended capabilities also have other uses for NASA. Detection of elements of low atomic number is of high interest to the aerospace community. High-strength aluminum alloys will be easily analyzed for composition. Silicon, a major contaminant in certain processes, will be detectable before the process is begun, possibly eliminating weld or adhesion problems. Exotic alloys will be evaluated for composition prior to being placed in service where lives depend on them. And in the less glamorous applications, such as bolts and fasteners, substandard products and counterfeit items will be evaluated at the receiving function and never allowed to enter the operation

Schramm, Harry F.; Kaiser, Bruce

2005-01-01

452

Vacuum systems for the ILC helical undulator  

SciTech Connect

The International Linear Collider (ILC) positron source uses a helical undulator to generate polarized photons of {approx}10 MeV at the first harmonic. Unlike many undulators used in synchrotron radiation sources, the ILC helical undulator vacuum chamber will be bombarded by photons, generated by the undulator, with energies mostly below that of the first harmonic. Achieving the vacuum specification of {approx}100 nTorr in a narrow chamber of 4-6 mm inner diameter, with a long length of 100-200 m, makes the design of the vacuum system challenging. This article describes the vacuum specifications and calculations of the flux and energy of photons irradiating the undulator vacuum chamber and considers possible vacuum system design solutions for two cases: cryogenic and room temperature.

Malyshev, O. B.; Scott, D. J.; Bailey, I. R.; Barber, D. P.; Baynham, E.; Bradshaw, T.; Brummitt, A.; Carr, S.; Clarke, J. A.; Cooke, P.; Dainton, J. B.; Ivanyushenkov, Y.; Malysheva, L. I.; Moortgat-Pick, G. A.; Rochford, J. [ASTeC, STFC Daresbury Laboratory, Warrington, WA4 4AD (United Kingdom); Cockcroft Institute, Warrington WA4 4AD (United Kingdom); ASTeC, STFC Daresbury Laboratory Warrington WA4 4AD (United Kingdom); Cockcroft Institute, Warrington WA4 4AD (United Kingdom) and Department of Physics, University of Liverpool, Oxford St. Liverpool L69 7ZE (United Kingdom); Department of Physics, University of Liverpool Oxford St. Liverpool L69 7ZE (United Kingdom); Cockcroft Institute, Warrington WA4 4AD (United Kingdom); DESY-Hamburg, Notkestrasse 85 22607 Hamburg (Germany); STFC Rutherford Appleton Laboratory Chilton, Didcot Oxfordshire OX11 0QX (United Kingdom); ASTeC, STFC Daresbury Laboratory Warrington WA4 4AD (United Kingdom); Cockcroft Institute, Warrington WA4 4AD (United Kingdom); Department of Physics, University of Liverpool Oxford St. Liverpool L69 7ZE (United Kingdom); Cockcroft Institute, Warrington WA4 4AD [United Kingdom and Department of Physics, University of Liverpool, Oxford St., Liverpool L69 7ZE (United Kingdom); STFC Rutherford Appleton Laboratory, Chilton Didcot Oxfordshire OX11 0QX (United Kingdom); Cockcroft Institute, Warrington WA4 4AD (United Kingdom); Department of Physics, University of Liverpool Oxford St. Liverpool L69 7ZE (United Kingdom); Institute of Particle Physics Phenomenology, University of Durham Durham DH1 3LE, (United Kingdom); CERN, CH-1211 Geneva 23 (Switzerland); STFC Rutherford Appleton Laboratory, Chilton Didcot Oxfordshire OX11 0QX (United Kingdom)

2007-07-15

453

Vacuum charge fractionlization re-examined  

E-print Network

We consider a model of a quantized fermion field that is based on the Dirac equation in one dimensional space and re-examine how the fermion number of the vacuum, or the vacuum charge, varies when an external potential is switched on. With this model, fractionization of the vacuum charge has been illustrated in the literature by showing that the external potential can change the vacuum charge from zero to a fractional number. Charge conservation then appears violated in this process. This is because the charge that has been examined in this context is only a part of the total charge of the vacuum. The total charge is conserved. It is not fractionalized unless the Dirac equation has a zero mode. Two other confusing aspects are discussed. One is concerned with the usage of the continuum limit and the other with the regularization of the current operator. Implications of these aspects of the vacuum problem are explored.

Y. Nogami

2008-08-01

454

The large-scale structure of vacuum  

E-print Network

The vacuum state in quantum field theory is known to exhibit an important number of fundamental physical features. In this work we explore the possibility that this state could also present a non-trivial space-time structure on large scales. In particular, we will show that by imposing the renormalized vacuum energy-momentum tensor to be conserved and compatible with cosmological observations, the vacuum energy of sufficiently heavy fields behaves at late times as non-relativistic matter rather than as a cosmological constant. In this limit, the vacuum state supports perturbations whose speed of sound is negligible and accordingly allows the growth of structures in the vacuum energy itself. This large-scale structure of vacuum could seed the formation of galaxies and clusters very much in the same way as cold dark matter does.

F. D. Albareti; J. A. R. Cembranos; A. L. Maroto

2014-05-15

455

Robot design for a vacuum environment  

NASA Technical Reports Server (NTRS)

The cleanliness requirements for many processing and manufacturing tasks are becoming ever stricter, resulting in a greater interest in the vacuum environment. Researchers discuss the importance of this special environment, and the development of robots which are physically and functionally suited to vacuum processing tasks. Work is in progress at the Center for robotic Systems in Microelectronics (CRSM) to provide a robot for the manufacture of a revolutionary new gyroscope in high vacuum. The need for vacuum in this and other processes is discussed as well as the requirements for a vacuum-compatible robot. Finally, researchers present details on work done at the CRSM to modify an existing clean-room compatible robot for use at high vacuum.

Belinski, S.; Trento, W.; Imani-Shikhabadi, R.; Hackwood, S.

1987-01-01

456

The large-scale structure of vacuum  

NASA Astrophysics Data System (ADS)

The vacuum state in quantum field theory is known to exhibit an important number of fundamental physical features. In this work we explore the possibility that this state could also present a nontrivial spacetime structure on large scales. In particular, we will show that by imposing the renormalized vacuum energy-momentum tensor to be conserved and compatible with cosmological observations, the vacuum energy of sufficiently heavy fields behaves at late times as nonrelativistic matter rather than as a cosmological constant. In this limit, the vacuum state supports perturbations whose speed of sound is negligible and accordingly allows the growth of structures in the vacuum energy itself. This large-scale structure of vacuum could seed the formation of galaxies and clusters very much in the same way as cold dark matter does.

Albareti, Franco D.; Cembranos, Jose A. R.; Maroto, Antonio L.

2014-10-01

457

Micro Raman Spectroscopy of Annealed Erbium Implanted GaN  

E-print Network

Wurtzite GaN epilayers grown by metal organic chemical vapor deposition on sapphire substrates were subsequently ion implanted with Er to a dose of 5×10¹? cm?². The implanted samples were annealed in nitrogen atmosphere ...

Vajpeyi, Agam P.

458

Design and fabrication of a tin-sulfide annealing furnace  

E-print Network

A furnace was designed and its heat transfer properties were analyzed for use in annealing thin-film tins-ulfide solar cells. Tin sulfide has been explored as an earth abundant solar cell material, and the furnace was ...

Lewis, Raymond (Raymond A.)

2011-01-01

459

Advanced Photon Source accelerator ultrahigh vacuum guide  

SciTech Connect

In this document the authors summarize the following: (1) an overview of basic concepts of ultrahigh vacuum needed for the APS project, (2) a description of vacuum design and calculations for major parts of APS, including linac, linac waveguide, low energy undulator test line, positron accumulator ring (PAR), booster synchrotron ring, storage ring, and insertion devices, and (3) cleaning procedures of ultrahigh vacuum (UHV) components presently used at APS.

Liu, C.; Noonan, J.

1994-03-01

460

Annealing twins in nanocrystalline fcc metals: A molecular dynamics simulation  

SciTech Connect

We report fully three-dimensional atomistic molecular dynamics studies of grain growth kinetics in nanocrystalline Cu of 5 nm average grain size. We observe the formation of annealing twins as part of the grain growth process. The grain size and energy evolution was monitored as a function of time for various temperatures, yielding an activation energy for the process. The atomistic mechanism of annealing twin formation from the moving boundaries is described.

Farkas, Diana [Department of Materials Science and Engineering, Virginia Tech, Blacksburg, Virginia 24060 (United States); Bringa, Eduardo; Caro, Alfredo [Chemistry, Materials and Life Sciences, Lawrence Livermore National Laboratory, Livermore, California 94550 (United States)

2007-05-01

461

Double-Pulsed Laser Annealing Technologies and Related Applications  

Microsoft Academic Search

New applications of the double-pulsed laser annealing (DPLA) technologies were opened up in the coming-generation high-performance devices: insulated gate bipolar transistors (IGBTs) and low-temperature polycrystalline silicon thin-film transistors (LTPS-TFTs). The DPLA system was equipped with two solid-state lasers of a green wavelength as pulse laser sources. The line-beam irradiation was done in the same way as conventional excimer laser annealing

Toshio Joshua Kudo

2006-01-01

462

Stochastic search in structural optimization - Genetic algorithms and simulated annealing  

NASA Technical Reports Server (NTRS)

An account is given of illustrative applications of genetic algorithms and simulated annealing methods in structural optimization. The advantages of such stochastic search methods over traditional mathematical programming strategies are emphasized; it is noted that these methods offer a significantly higher probability of locating the global optimum in a multimodal design space. Both genetic-search and simulated annealing can be effectively used in problems with a mix of continuous, discrete, and integer design variables.

Hajela, Prabhat

1993-01-01

463

Air Atmosphere Annealing Effects on LSO:Ce Crystal  

Microsoft Academic Search

Cerium-doped lutetium oxyorthosilicate Lu2SiO5:Ce crystal is a well-known scintillator with an excellent figure-of-merit. In this paper, air annealing was used to further improve its scintillation properties. The samples cut from Czochralski grown Lu2SiO5:Ce crystals were annealed in air atmosphere at 1400°C for 10 h. Based on the analysis of the difference in the crystal's spectra (such as absorption, emission, and

Dongzhou Ding; He Feng; Guohao Ren; Martin Nikl; Laishun Qin; Shangke Pan; Fan Yang

2010-01-01

464

Forming an age hardenable aluminum alloy with intermediate annealing  

NASA Astrophysics Data System (ADS)

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.

Wang, Kaifeng; Carsley, John E.; Stoughton, Thomas B.; Li, Jingjing; Zhang, Lianhong; He, Baiyan

2013-12-01

465

Laser annealing of implanted silicon carbide and Raman characterization  

Microsoft Academic Search

Pulsed-laser-based methods have been applied for post-implant annealing of p-type Al doped 4H-SiC wafers in order to restore the crystal structure and to electrically activate the doping species. The annealing was performed with the second (532nm) and third (355nm) harmonic of a Nd:YAG laser at 4ns pulse duration. The epilayers were characterized by micro-Raman spectroscopy under surface and cross sectional

I. Zergioti; A. G. Kontos; K. Zekentes; C. Boutopoulos; P. Terzis; Y. S. Raptis

2006-01-01

466

Method and apparatus for selectively annealing heterostructures using microwave  

NASA Technical Reports Server (NTRS)

The present invention discloses a process for selectively annealing heterostructures using microwaves. A heterostructure, comprised of a material having higher microwave absorption and a material having lower microwave absorption, is exposed to microwaves in the cavity. The higher microwave absorbing material absorbs the microwaves and selectively heats while the lower microwave absorbing material absorbs small amounts of microwaves and minimally heats. The higher microwave absorbing material is thereby annealed onto the less absorbing material which is thermally isolated.

Atwater, Harry A. (Inventor); Brain, Ruth A. (Inventor); Barmatz, Martin B. (Inventor)

1998-01-01

467