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1

Radiative phenomena in CW laser annealing  

SciTech Connect

Recrystallization of thin semiconductor films can yield improved electrical and crystalline properties. Recrystallization is often effected by using a laser source to melt the semiconductor film, which has been deposited on an amorphous insulating substrate. Although temperature measurement data would be valuable for the processing of materials on a microscopic scale, very few such measurements have been presented. It is the intent of this paper to demonstrate work toward the development of completely noninvasive experimental methods for in situ quantitative analysis of the laser annealing process, based on the acquisition of surface radiative data.

Grigoropoulos, C.P.; Dutcher, W.E. Jr.; Barclay, K.E. (Univ. of Washington, Seattle (United States))

1991-08-01

2

Breakdown Phenomena of a Vacuum Interrupter after Current Zero  

Microsoft Academic Search

A study on breakdown phenomena in a vacuum interrupter was conducted with the use of a numerical model based on the continuous transition model by Andrews and Varey (1). The vacuum model was validated against test data for the device under consideration. The study aim to find the mechanisms that prompt the breakdown of the interrupter as well as interrupting

Lionel R. Orama

3

Vacuum annealing temperature on spray In2S3 layers  

NASA Astrophysics Data System (ADS)

Indium sulfide In2S3 thick films are deposited on glass substrates using spray technique over the optimum conditions experiments (Ts = 340 °C, S/In = 2). The films are polycrystalline and have thickness of about 1.8 ?m. These films are annealed in a vacuum sealed pyrex tubes (10-5 torr). Physico-chemical characterizations by SEM observation, X-ray diffraction and EDX analysis are undertaked on these films. This treatment has improved crystallinity of samples. It has allowed thus to stabilize ? and ? varieties of In2S3 material. In2O3 and In6S7 phases have appeared with very weak intensities at high temperatures. The best structure quality are obtained at 300 °C for the optimum annealed temperature (Ts = 340 °C, S/In = 2), for which samples are constituted in dominance by ? phase oriented preferentially towards (1 0 2). The grain size is 42 nm of this phase. Chemical composition of such films has changed relatively to non-treated film but it seems not be affected by treatment temperature. Atomic molar ratio S/In is obtained for 0.9. Optical study shows that these layers are transparent in the visible and optical direct band gap increases as function of annealed temperature.

Bouguila, Nourredine; Timoumi, Abdelmajid; Bouzouita, Hassen

2014-02-01

4

Change in optical properties of CuI crystals upon annealing in vacuum  

NASA Astrophysics Data System (ADS)

Copper iodide crystals with different compositions of crystalline defects have been prepared using the developed technique for their synthesis and annealing in vacuum with subsequent quenching. The spectra of absorption, excitation, and photoluminescence of the CuI crystals, as well as their electrical resistance, have been analyzed. It has been found that the optical properties of the crystals change as a result of the increase in the number of point defects and inclusions of the second phase in the samples after high-temperature annealings (as compared to low-temperature annealings). This effect is caused by the deviation of the composition of the material from stoichiometry during annealing in vacuum.

Gruzintsev, A. N.; Zagorodnev, V. N.

2012-01-01

5

Comparing Effects of Vacuum Annealing and Dry Oxidation on the Photoluminescence of Porous Si  

Microsoft Academic Search

Effects of vacuum annealing and dry oxidation on the photoluminescence properties of porous Si are reported. Anodized porous Si is formed by electrochemical etching in an aqueous HF solution of 16 to 48 wt% with a current density of 10 to 70 mA\\/cm2. A subsequent vacuum annealing (from 400°C to 800°C) weakens the intensity of the photoluminescence, whereas, oxidation using

Masao Yamada; Kazuaki Kondo

1992-01-01

6

Electron paramagnetic resonance of dangling bond centers in vacuum-annealed porous silicon  

NASA Astrophysics Data System (ADS)

Electron paramagnetic resonance (EPR) of centers produced in porous silicon (PS) by heat treatment in vacuum is investigated. Annealing in the temperature range of 400-600 °C and vacuum up to 5×10-5 Torr increases the EPR line intensity of Pb centers in a way depending on the time of annealing. This can be explained by hydrogen depassivation of the Pb centers. An isotropic line with g=2.0055, usually attributed to disordered Si dangling bonds, appears after vacuum annealing of some minutes but at a longer heat treatment its intensity decreases. At room temperature this decrease is exponential with a time constant of a few minutes, depending on the level of vacuum. Heat treatment of PS in vacuum leads to amplification of the Pb EPR spectrum after exposition of samples to air at room temperature.

Laiho, R.; Vlasenko, L. S.

1995-08-01

7

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

NASA Astrophysics Data System (ADS)

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 °C 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 °C 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; 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

Low vacuum annealing of cellulose acetate on nickel towards transparent conductive CNT-graphene hybrid films.  

PubMed

We report a versatile method based on low vacuum annealing of cellulose acetate on nickel (Ni) surface for rapid fabrication of graphene and carbon nanotube (CNT)-graphene hybrid films with tunable properties. Uniform films mainly composed of tri-layer graphene can be achieved via a surface precipitation of dissociated carbon at 800 °C for 30 seconds under vacuum conditions of ?0.6 Pa. The surface precipitation process is further found to be efficient for joining the precipitated graphene with pre-coated CNTs on the Ni surface, consequently, generating the hybrid films. As expected, the hybrid films exhibit substantial opto-electrical and field electron emission properties superior to their individual counterparts. The finding suggests a promising route to hybridize the graphene with diverse nanomaterials for constructing novel hybrid materials with improved performances. PMID:24852931

Nguyen, Duc Dung; Tiwari, Rajanish N; Matsuoka, Yuki; Hashimoto, Goh; Rokuta, Eiji; Chen, Yu-Ze; Chueh, Yu-Lun; Yoshimura, Masamichi

2014-06-25

10

Effect of zinc addition and vacuum annealing time on the properties of spin-coated low-cost transparent conducting 1 at% Ga-ZnO thin films  

NASA Astrophysics Data System (ADS)

Pure and 1 at% gallium (Ga)-doped zinc oxide (ZnO) thin films have been prepared with a low-cost spin coating technique on quartz substrates and annealed at 500 °C in vacuum ˜10-3 mbar to create anion vacancies and generate charge carriers for photovoltaic application. Also, 0.5-1.5 at% extra zinc species were added in the precursor sol to investigate changes in film growth, morphology, optical absorption, electrical properties and photoluminescence. It is shown that 1 at% Ga-ZnO thin films with 0.5 at% extra zinc content after vacuum annealing for 60 min correspond to wurtzite-type hexagonal structure with (0001) preferred orientation, electrical resistivity of ˜9 × 10-3 ? cm and optical transparency of ˜65-90% in the visible range. Evidence has been advanced for the presence of defect levels within bandgap such as zinc vacancy (VZn), zinc interstitial (Zni), oxygen vacancy (Vo) and oxygen interstitial (Oi). Further, variation in ZnO optical bandgap occurring with Ga doping and insertion of additional zinc species has been explained by invoking two competing phenomena, namely bandgap widening and renormalization, usually observed in semiconductors with increasing carrier concentration.

Srivastava, Amit Kumar; Kumar, Jitendra

2013-12-01

11

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

Microsoft Academic Search

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

J. Massies; F. Lemaire-Dezaly

1985-01-01

12

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

13

Evidence for bicarbonate formation on vacuum annealed TiO 2(110) resulting from a precursor-mediated interaction between CO 2 and H 2O  

Microsoft Academic Search

The reaction of CO2 and H2O to form bicarbonate (HCO?3) was examined on the nearly perfect and vacuum annealed surfaces of TiO2(110) with temperature programmed desorption (TPD), static secondary ion mass spectrometry (SSIMS) and high resolution electron energy loss spectrometry (HREELS). The vacuum annealed TiO2(110) surface possesses oxygen vacancy sites that are manifested in electronic EELS by a loss feature

Michael A Henderson

1998-01-01

14

Influence of annealing in vacuum and in air on magnetic, crystallographic and morphological properties of thin YIG films  

NASA Astrophysics Data System (ADS)

The Yttrium Iron Garnet (YIG) is chosen by our laboratory for the integration of passive components in the microwaves domain and for the miniaturization of integrated inductors and transformers. Magnetic and morphological characterizations are essential for the development of these components. To fabricate a micro-inductor of solenoid type, we have deposited on an alumina substrate, by RF sputtering, a thin YIG film between two layers of copper. We have also used the photolithography technique in a clean room to obtain the desired pattern of the coil. The YIG films are amorphous after deposition, the annealing at 740°C for 2 hours is necessary for them to be crystallized and to have magnetic properties. To avoid the deterioration of copper layers, the Classical Thermal Annealing (CTA) was replaced by a Vacuum Thermal Annealing (VTA). Before manufacturing the integrated inductor, it is interesting to do the magnetic, crystallographic and morphological characterizations of YIG films after annealing with both techniques of thermal treatment. To check the quality of the prototype, we have done different characterizations: VSM, Kerr effect, XRD, SEM. The results obtained with VTA were better than of CTA comparing them with bulk YIG properties.

Siblini, A.; Khalil, I.; Chatelon, J. P.; Blanc-Mignon, M. F.; Jamon, D.; Rousseau, J. J.

2013-01-01

15

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

16

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

17

Increased photo- and electroluminescence by zone annealing of spin-coated and vacuum-sublimed amorphous films producing crystalline thin films  

NASA Astrophysics Data System (ADS)

Spin-coated and vacuum sublimed amorphous thin films (˜100 nm thick) were converted into single crystalline films with a simple moving-zone-annealing technique, in which a heated metal wire generated a narrow annealed zone in the film as it is moved across the sample. This annealing resulted in both the photoluminescence and electroluminescence to increase dramatically (by 3-4 times), for example with Ru(bpy)3(ClO4)2 and aluminum 8-hydroxyquinoline, (Alq3), as light emitting devices. This technique is of interest in improving the behavior of highly luminescent thin film optoelectronic devices.

Liu, Chong-Yang; Bard, Allen J.

2003-12-01

18

Maximum density of Pb centers at the (111) Si/SiO2 interface after vacuum anneal  

NASA Astrophysics Data System (ADS)

The density of interfacial [111]Pb centers, i.e., 0Si?Si3 defects with unpaired bond along [111], has been accurately determined by K-band electron spin resonance at 4.3 K on (111)Si/SiO2 structures using various oxidation conditions. Reversible defect depassivation (dehydrogenation) has been monitored by post-oxidation vacuum annealing in the temperature range 752-835 °C. It was found that the density of both ESR active and passivated Pb defects is (11.4±0.6)×1012 cm-2 on all (111)Si/SiO2 interfaces prepared by oxidation in dry O2 at 920-1000 °C. This number appears to be a natural constant predominantly set by the oxidation temperature; variations in oxidation oxygen pressure (1.5×10-5-840 Torr) and time have little influence. The Pb's are found to account for all the fast interface states.

Stesmans, A.; Van Gorp, G.

1990-12-01

19

Transformation of the electronic structure of the SnO2 - x /MWCNT nanocomposite under high-vacuum annealing conditions  

NASA Astrophysics Data System (ADS)

The transformation of the structural phase state and the electronic structure of the SnO2 - x /MWCNT composite has been studied using X-ray spectroscopy and high-resolution transmission electron microscopy. It has been shown that the character of the interaction of the metal-oxide component of the composite with the array of carbon nanotubes depends on the structural state of tin oxide in globules of the metal-oxide component. In the initial composite with a large content of amorphous tin oxide, covalent functionalization of the MWCNT surface occurs. High-vacuum annealing results in the formation of a nanocrystalline structure in globules of the metal-oxide component and is accompanied by changes in the character of its interaction with carbon tubes.

Bolotov, V. V.; Nesov, S. N.; Korusenko, P. M.; Povoroznyuk, S. N.

2014-09-01

20

HF-reignition phenomena related to post-arc current in vacuum interrupters  

NASA Astrophysics Data System (ADS)

After interruption of a high-frequency (hf) current by a vacuum arc, two distinct types of reignition can be observed. The first type follows immediately after interruption, the second type tends to allow a currentless pause of a few tenths of a microsecond. The post-arc current that flows after hf-current interruption has been measured and has a peak of several A and a decay time of a several hundreds of ns. A dynamic sheath model for the decaying plasma after hf current interruption has been used successfully to model the measured post-arc current waveshapes. The first type of reignition may be attributed to thermal stress during the period in which no ion sheath has been formed yet, the second type to high electric fields, either due to the ion sheath, or due to the TRV, the weight of each depending on gaplength and di/dt.

Smeets, Rene P.; Li, Honqun; Lamerichs, Nico J.; Kaneko, Eiji

1994-05-01

21

Effects of carbon fiber gas pressure, temperature and deposition distance on thermo fluids phenomena in vacuum deposition machine  

NASA Astrophysics Data System (ADS)

A numerical analysis method (DSMC, Direct Simulation Monte Carlo)[1] was developed to simulate the molecular motion of rarefied gases. In the present paper, numerical approaches by the DSMC method have been carried out. By the computation model of CC-40F carbon coater, the cylindrical deposition machine has axial symmetry; the flows inside the vacuum chamber were analyzed. The substrates were put on the bottom and the fiber near the ceiling in the computational domain. In the computational model, air and carbon molecules are working ones. The effects of the air gas pressure variation in the chamber, the effects of the deposition distance variation and the surface temperature variation of the carbon fiber on thermo fluids phenomena are discussed and visualized. Changing the number density of carbon and air, the temperature of the carbon and the velocity of the carbon in the chamber are discussed. With changing the surface temperature of the carbon fiber, qualitative assay of experiment and simulation result is in similar trend very well. The DSMC method is a forceful tool for the study of rarefied gas flow in vacuum deposition machine.

He, Ying; Ota, M.; Stefanov, S. K.

2008-09-01

22

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

23

Superconducting magnesium diboride films on Si with Tc0~24 K grown via vacuum annealing from stoichiometric precursors  

Microsoft Academic Search

Superconducting magnesium diboride films with Tc0~24 K and sharp transition ~1 K were prepared on Si by pulsed-laser deposition from stoichiometric MgB2 target. Contrary to previous reports, anneals at 630 °C and a background of 2×10-4 Ar\\/4%H2 were performed without the requirement of Mg vapor or Mg cap layer. This integration of superconducting MgB2 film on Si may thus prove

H. Y. Zhai; H. M. Christen; L. Zhang; C. Cantoni; M. Paranthaman; B. C. Sales; D. K. Christen; D. H. Lowndes

2001-01-01

24

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

25

Annealing effect on the particle size and chemical composition of activated carbon obtained from vacuum furnace of teak sawdust  

NASA Astrophysics Data System (ADS)

Activated carbon was produced from sawdust by using physical method in a high temperature vacuum furnace without additional chemical. Fast pyrolysis process was carried out prior in fluidized a bed furnace to produce char before activation process. Experiments were conducted to investigate the influence of various process parameters such as particle size, activation temperature and activation time on the quality of the activated carbon. In addition, the chemical composition studies were done by using x-ray fluorescence (XRF) spectroscopy. The crystallite sizes were calculated by using Scherer equation based on x-ray diffraction (XRD) spectroscopy data. The pyrolysis temperature and time were varied from 600°C to 900°C and from 3 hours to 6 hours, respectively. The particle size of activated carbon was increase with increasing temperature. The composition and crystallite size of the prepared activated carbon was compared with the non-activated carbon. The results indicated that the teak sawdust carbon could be employed as a low cost alternative to produce commercial activated carbon.

Armynah, B.; Tahir, D.; Jaya, N.

2014-09-01

26

Influence of vacuum annealing on microstructure and magnetic properties of (Ba 0.8Sr 0.2)(Ti 0.3Fe 0.7)O 3 ceramic  

NASA Astrophysics Data System (ADS)

Fe-doped (Ba 0.8Sr 0.2)TiO 3 ceramic was prepared by solid-state reaction, and room-temperature ferromagnetism was achieved via vacuum annealing. The effect of annealing on microstructure, magnetic properties and exchange mechanism was investigated using X-ray diffraction, Mössbauer spectroscopy, and vibrating sample magnetometer. The as-prepared and annealed samples are shown to be monophasic, crystallizing in a 6H-BaTiO 3-type hexagonal perovskite structure. The paramagnetism is exhibited in the as-prepared state, arising from the super-exchange interactions of Fe 3+ on tetrahedral and octahedral Ti sites. On the other hand, vacuum annealing is proved to be a feasible way for Fe-doped (Ba 1-xSr x)TiO 3 to obtain ferromagnetism via modifying the Fe occupational distribution. The super-exchange interactions between Fe 3+ on pentahedral and octahedral Ti sites lead to the room-temperature ferromagnetism observed in the annealed sample.

Lin, Fangting; Shi, Wangzhou

2010-04-01

27

Effect of Annealing Temperature on Tribological Properties and Material Transfer Phenomena of CrN and CrAlN Coatings  

NASA Astrophysics Data System (ADS)

This study evaluates the effects of annealing temperature and of the oxides produced during annealing processes on the tribological properties and material transfer behavior between the PVD CrN and CrAlN coatings and various counterface materials, i.e., ceramic alumina, steel, and aluminum. CrAlN coating has better thermal stability than CrN coating in terms of hardness degradation and oxidation resistance. When sliding against ceramic Al2O3 counterface, both CrN and CrAlN coatings present excellent wear resistance, even after annealing at 800 °C. The Cr-O compounds on the coating surface could serve as a lubricious layer and decrease the coefficient of friction of annealed coatings. When sliding against steel balls, severe material transfer and adhesive wear occurred on the CrN and CrAlN coatings annealed at 500 and 700 °C. However, for the CrAlN coating annealed at 800 °C, much less material sticking and only small amount of adhesive wear occurred, which is possibly due to the formation of a continuous Al-O layer on the coating outer layer. The sliding tests against aluminum balls indicate that both coatings are not suitable as the tool coatings for dry machining of aluminum alloys.

Wang, Linlin; Nie, X.

2013-10-01

28

Nanomechanical characteristics of annealed Si/SiGe superlattices  

NASA Astrophysics Data System (ADS)

In this study, the nanomechanical damage was investigated on the annealed Si/SiGe strained-layer superlattices (SLSs) deposited using an ultrahigh-vacuum chemical vapor deposition (UHVCVD). Nanoscratch, nanoindenter, atomic force microscopy (AFM), and transmission electron microscopy (TEM) techniques were used to determine the nanomechanical behavior of the SiGe films. With a constant force applied, greater hardness number and larger coefficients of friction ( ?) were observed on the samples that had been annealed at 600 °C, suggesting that annealing of the Si/SiGe SLSs can induce greater shear resistance. AFM morphological studies of the Si/SiGe SLSs revealed that pile-up phenomena occurred on both sides of each scratch, with the formation of some pellets and microparticles. The Si/SiGe SLSs that had been subjected to annealing under various conditions exhibited significantly different features in their indentation results. Indeed, the TEM images reveal slight dislocation propagation in the microstructures. Thus, the hardness and elastic modulus can be increased slightly after annealing treatment because the existence of comparatively unstable microstructures. It is suggested that cracking phenomena dominate the damage cause of Si/SiGe SLSs.

Wu, Ming-Jhang; Wen, Hua-Chiang; Wu, Shyh-Chi; Yang, Ping-Feng; Lai, Yi-Shao; Hsu, Wen-Kuang; Wu, Wen-Fa; Chou, Chang-Pin

2011-08-01

29

Phenomena of fault-arc propagation on cables and wires for space applications in vacuum and oxygen-enriched atmosphere and air  

Microsoft Academic Search

Investigations of fault arc propagation on spacecraft cables under spacecraft specific conditions, e.g. vacuum, normal and oxygen enriched atmosphere have been performed. Typical patterns of fault arc extinction have been identified and their consequences with respect to causes of damages are discussed. The results indicate that for a given test current and test voltage the behavior of the arc and

F. R. Frontzek; D. Koenig; M. D. Judd; H. J. Reher

1994-01-01

30

Superconducting magnesium diboride films on Si with Tc0~24K grown via vacuum annealing from stoichiometric precursors  

SciTech Connect

Superconducting magnesium diboride films with T{sub c0} {approx} 24 K and sharp transition {approx}1 K were prepared on Si by pulsed-laser deposition from stoichiometric MgB{sub 2} target. Contrary to previous reports, anneals at 630 C and a background of 2 x 10{sup -4} Ar/4%H{sub 2} were performed without the requirement of Mg vapor or Mg cap layer. This integration of superconducting MgB{sub 2} film on Si may thus prove enabling in superconductor-semiconductor device applications. Images of surface morphology and cross-section profiles by scanning electron microscopy show that the films have a uniform surface morphology and thickness. Energy-dispersive spectroscopy study reveals these films were contaminated with oxygen, originating either from the growth environment or from sample exposure to air. The oxygen contamination may account for the low T{sub c} for those in situ annealed films, while the use of Si as a substrate does not result in a decrease in T{sub c} as compared to other substrates.

Zhai, H.Y.

2001-10-01

31

Superconducting magnesium diboride films on Si with T{sub c0}{approx}24 K grown via vacuum annealing from stoichiometric precursors  

SciTech Connect

Superconducting magnesium diboride films with T{sub c0}{approx}24 K and sharp transition {approx}1 K were prepared on Si by pulsed-laser deposition from stoichiometric MgB{sub 2} target. Contrary to previous reports, anneals at 630 C and a background of 2 x 10{sup -4} Ar/4%H{sub 2} were performed without the requirement of Mg vapor or Mg cap layer. This integration of superconducting MgB{sub 2} film on Si may thus prove enabling in superconductor-semiconductor device applications. Images of surface morphology and cross-section profiles by scanning electron microscopy show that the films have a uniform surface morphology and thickness. Energy-dispersive spectroscopy study reveals these films were contaminated with oxygen, originating either from the growth environment or from sample exposure to air. The oxygen contamination may account for the low T{sub c} for those in situ annealed films, while the use of Si as a substrate does not result in a decrease in T{sub c} as compared to other substrates.

Zhai, H. Y.; Christen, H. M.; Zhang, L.; Cantoni, C.; Paranthaman, M.; Sales, B. C.; Christen, D. K.; Lowndes, D. H.

2001-10-15

32

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

33

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

34

A numerical simulation of the phenomena in Be plasma  

Microsoft Academic Search

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.

Camelia Gavrila; Cristian P. Lungu; Ion Gruia

2011-01-01

35

Superfluid analogies of cosmological phenomena  

E-print Network

Superfluid 3He-A gives example of how chirality, Weyl fermions, gauge fields and gravity appear in low emergy corner together with corresponding symmetries, including Lorentz symmetry and local SU(N). This supports idea that quantum field theory (Standard Model or GUT) is effective theory describing low-energy phenomena. * Momentum space topology of fermionic vacuum provides topological stability of universality class of systems, where above properties appear. * BCS scheme for 3He-A incorporates both ``relativistic'' infrared regime and ultraviolet ``transplanckian'' range: subtle issues of cut-off in quantum field theory and anomalies can be resolved on physical grounds. This allows to separate ``renormalizable'' terms in action, treated by effective theory, from those obtained only in ``transPlanckian'' physics. * Energy density of superfluid vacuum within effective theory is ~ E_{Planck}^4. Stability analysis of ground state beyond effective theory leads to exact nullification of vacuum energy: equilibrium...

Volovik, G E

2001-01-01

36

Heat Transport Analysis for Flash Lamp Annealing  

Microsoft Academic Search

The silicon wafer temperature change during flash lamp annealing is theoretically evaluated. A calculation model is developed on the basis of a finite difference method taking into account various heat transport phenomena, such as heat radiation from a lamp to a silicon surface, reflection at the silicon surface, heat radiation from a hot silicon surface, light absorption in silicon, and

Hitoshi Habuka; Akiko Hara; Takeshi Karasawa; Masaki Yoshioka

2007-01-01

37

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

38

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

39

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

40

Thermalized Vacuum and Vacuum Effects  

E-print Network

Some of the well-known effects regarding the vacuum are revisited under the formalism of the imaginary-time field theory. From these effects, they could imply the existence of one thermal vacuum in different circumstances. The imaginary-time hamiltonian of the vacuum is found to provide not only exact distribution functions in the calculations of the Casimir effect and the Van der Waals force but also cutoff functions. The thermal bath for the Unruh effect is constructed from the imaginary-time Green function. From the field theory in the curved space-time, field quantizations are defined according to different vacuum states and lead to the Hawking radiation; the introduced conformal invariance agree with the formalism of the imaginary-time field theory. The induced Green functions in the curved space-time are in accordance with those from the picture given from the thermal vacuum.

Yi-Cheng Huang

2013-11-14

41

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

PubMed Central

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

2014-01-01

42

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

43

Understanding the thermal annealing process on metallic thin films  

NASA Astrophysics Data System (ADS)

Thermal annealing is an usual process used for intrinsic stress liberation, structural improving, and surface roughness control in materials. In a qualitative way, annealing modifies the surface morphology of materials with temperature and time. In this work, a methodology to explain the surface modification of thin films when they are submitted to an annealing process is discussed. Two thermally evaporated Au films with 200 nm-thicknesses were post-annealed in a vacuum chamber at 100 °C with an argon atmosphere, and annealing times from 0 to 1000 minutes. Each Au film grown at different rate deposition was cyclical annealed and imaged under different annealing times. Data obtained from high quality AFM images after different annealing times of Au samples were used to calculate surface parameters such as roughness, grain size, and slope at the border, also the respective exponents as a function of the annealing time. The experimental results allow understanding the temporal evolution of the annealing process, as a rearrangement of the surface protrusions.

Alonzo-Medina, G. M.; González-González, A.; Sacedón, J. L.; Oliva, A. I.

2013-06-01

44

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

45

Annealing of plasma-sprayed WC-Co coating  

Microsoft Academic Search

The effects of vacuum annealing on the physical soundness and resultant tensile bond strength and wear properties of plasma-sprayed WC-17%Co coatings on a ductile cast iron substrate have been investigated. The as-sprayed specimens were annealed at temperatures from 500 to 1000 °C for up to 12 h. The results showed that, due to differential sintering within the coating, vertical cracks

L. C. Lim; S. C. Lim; M. O. Lai; S. F. Chong; S. Alli

1996-01-01

46

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

47

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

48

Vacuum Technology: Vacuum Technology III  

NSDL National Science Digital Library

This is a link to a PDF version of lecture slides that discuss gas sources in a vacuum. The presentation explains concepts such as vapor pressure curves, thermal desorption and first and second order desorption. Keywords: Vaporization, desorption, diffusion, permeation, backstreaming

Rack, Philip D.

2012-12-12

49

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

50

Vacuum waves  

NASA Astrophysics Data System (ADS)

An exact solution of the five-dimensional field equations is studied which describes waves in the classical Einstein vacuum. While the solution is essentially 5D in nature, the waves exist in ordinary 3D space. They should not be confused with standard gravitational waves, since their phase velocity can exceed that of light. They resemble de Broglie waves, and may give insight to wave-particle duality.

Wesson, Paul S.

2013-05-01

51

Influence of the doping and annealing atmosphere on zinc oxide thin films deposited by spray pyrolysis  

Microsoft Academic Search

Undoped and doped (indium and aluminium) zinc oxide (ZnO) thin films have been prepared by spray pyrolysis, and the effect of the doping and annealing atmosphere on the electrical, optical and structural properties of the produced films has been investigated. The deposited films have a high resistivity. Annealing the films in an argon atmosphere or under vacuum leads to a

P Nunes; A Malik; B Fernandes; E Fortunato; P Vilarinho; R Martins

1999-01-01

52

Vacuum Technology: Kinetic Theory of Gas  

NSDL National Science Digital Library

This is a PDF version of lecture slides that discuss the kinetic theory of gases. Slide topics include vacuum basics, kinetic pressure of an ideal gas, pressure and molecular velocity, basic equations from kinetic theory, gas laws, and gas transport phenomena. Numerous charts and mathematical formulas are presented. Keywords: Boltzman's constant, collision frequency, molecular velocity, Boyle's law, Charles' law, Dalton's law

Rack, Philip D.

2012-12-14

53

Vacuum phenomena in insufficiency fractures of the sacrum  

Microsoft Academic Search

Objective. Insufficiency fractures of the sacrum are found in women who have undergone radiation therapy to the lower abdomen as well\\u000a as those suffering from osteoporosis of postmenopausal, steroid-induced, or primary biliary cirrhosis-related origin. Increased\\u000a up-take in bone scintigraphy and osteolytic changes in these fractures can be misinterpreted as bone metastases, leading to\\u000a unnecessary biopsies and other procedures in the

Axel Stiibler; Reiner Beck; Reiner Bartl; Dorothea Schmidt; Maximilian Reiser

1995-01-01

54

Tunable metal-insulator transitions in bilayer graphene by thermal annealing  

NASA Astrophysics Data System (ADS)

Tunable and highly reproducible metal-insulator transitions have been observed in bilayer graphene upon thermal annealing at 400 K under high vacuum conditions. Before annealing, the sample is metallic in the whole temperature regime of study. Upon annealing, the conductivity changes from metallic to that of an insulator and the transition temperature is a function of annealing time. The pristine metallic state can be reinstated by exposing to air thereby inducing changes in the electronic properties by adsorbing water vapor, which makes graphene a technologically promising material for sensor applications.

Kalon, Gopinadhan; Shin, Young Jun; Yang, Hyunsoo

2011-06-01

55

Science and Paranormal Phenomena  

E-print Network

In order to ground my approach to the study of paranormal phenomena, I first explain my operational approach to physics, and to the ``historical'' sciences of cosmic, biological, human, social and political evolution. I then indicate why I believe that ``paranormal phenomena'' might --- but need not --- fit into this framework. I endorse the need for a new theoretical framework for the investigation of this field presented by Etter and Shoup at this meeting. I close with a short discussion of Ted Bastin's contention that paranormal phenomena should be {\\it defined} as contradicting physics.

H. Pierre Noyes

1999-06-03

56

Science and Paranormal Phenomena  

SciTech Connect

In order to ground my approach to the study of paranormal phenomena, I first explain my operational approach to physics, and to the ''historical'' sciences of cosmic, biological, human, social and political evolution. I then indicate why I believe that ''paranormal phenomena'' might-but need not- fit into this framework. I endorse the need for a new theoretical framework for the investigation of this field presented by Etter and Shoup at this meeting. I close with a short discussion of Ted Bastin's contention that paranormal phenomena should be defined as contradicting physics.

Noyes, H. Pierre

1999-06-03

57

Science and Paranormal Phenomena  

E-print Network

In order to ground my approach to the study of paranormal phenomena, I first explain my operational approach to physics, and to the ``historical'' sciences of cosmic, biological, human, social and political evolution. I then indicate why I believe that ``paranormal phenomena'' might --- but need not --- fit into this framework. I endorse the need for a new theoretical framework for the investigation of this field presented by Etter and Shoup at this meeting. I close with a short discussion of Ted Bastin's contention that paranormal phenomena should be {\\it defined} as contradicting physics.

Noyes, H P

1999-01-01

58

Semiconducting behaviour of thin bismuth films vacuum-deposited at different substrate temperatures  

Microsoft Academic Search

Thin bismuth films (thickness 25 nm) have been vacuum-deposited onto glass substrates at different substrate temperatures in a vacuum of 2×10-5 torr. The resistance of the films has been measured as a function of temperaturein situ during and after annealing. It is found that the resistance of all the annealed films decreases with increasing temperature thus showing a semiconducting type

V. Damodara Das; S. Vaidehi

1984-01-01

59

Annealed Discriminant Analysis  

Microsoft Academic Search

Motivated by the analogies to statistical physics, the deter- ministic annealing (DA) method has successfully been demonstrated in a variety of application. In this paper, we explore a new methodology to devise the classifier under the DA method. The differential cost func- tion is derived subject to a constraint on the randomness of the solution, which is governed by the

Wang Gang; Zhang Zhihua; Frederick H. Lochovsky

60

Vacuum self-magnetization?  

Microsoft Academic Search

We study vacuum properties in a strong magnetic field as the zero temperature and zero density limit of quantum statistics. For charged vector bosons (W bosons) the vacuum energy density diverges for B > Bc = mw2\\/e, leading to vacuum instability. A logarithmic divergence of vacuum magnetization is found for B = Bc, which suggests that if the magnetic field

H. Pe´rez Rojas; E. Rodri´guez Querts

2006-01-01

61

[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

62

STRUCTURAL AND MORPHOLOGICAL CHANGES IN Ag:TiN NANOCOMPOSITE FILMS PROMOTED BY IN-VACUUM  

E-print Network

ABSTRACT Thin films composed of titanium nitride doped with silver were deposited by DC reactive sputtering in the thin films, the increase of the annealing temperature promotes coating's crystallinity and some Ag grain growth. Keywords: Titanium nitride; silver; vacuum annealing; morphology; structure; 1

Boyer, Edmond

63

Natural vacuum electronics  

NASA Technical Reports Server (NTRS)

The ambient natural vacuum of space is proposed as a basis for electron valves. Each valve is an electron controlling structure similiar to a vacuum tube that is operated without a vacuum sustaining envelope. The natural vacuum electron valves discussed offer a viable substitute for solid state devices. The natural vacuum valve is highly resistant to ionizing radiation, system generated electromagnetic pulse, current transients, and direct exposure to space conditions.

Leggett, Nickolaus

1990-01-01

64

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

65

CCD Hot Pixel Annealing  

NASA Astrophysics Data System (ADS)

Hot pixel annealing will continue to be performed once every 4 weeks. The CCD TECswill be turned off and heaters will be activated to bring the detectortemperatures to about +20C. This state will be held for approximately6 hours, after which the heaters are turned off, the TECs turned on,and the CCDs returned to normal operating condition. To assess the effectiveness of the annealing, a bias and four dark images will be taken before and after the annealing procedure for both WFC and HRC.The HRC darks are taken in parallel with the WFC darks.The charge transfer efficiency {CTE} of the ACS CCD detectors declinesas damage due to on-orbit radiation exposure accumulates. This degradationhas been closely monitored at regular intervals, because it is likely todetermine the useful lifetime of the CCDs.We combine the annealling activity with the charge transfer efficiency monitoring and also merge into the routine dark image collection. To this end, the CTE monitoring exposures have been moved into this proposal . All the data for this program is acquired using internal targets {lamps} only,so all of the exposures should be taken during Earth occultation time{but not during SAA passages}.This program emulates the ACS pre-flight ground calibration and post-launchSMOV testing {program 8948}, so that results from each epoch can be directlycompared. Extended Pixel Edge Response {EPER} and First Pixel Response {FPR}data will be obtained over a range of signal levels for both theWide Field Channel {WFC}, and the High Resolution Channel {HRC}.

Cox, Colin

2005-07-01

66

CCD Hot Pixel Annealing  

NASA Astrophysics Data System (ADS)

Hot pixel annealing will continue to be performed once every 4 weeks. The CCD TECswill be turned off and heaters will be activated to bring the detectortemperatures to about +20C. This state will be held for approximately6 hours, after which the heaters are turned off, the TECs turned on,and the CCDs returned to normal operating condition. To assess the effectiveness of the annealing, a bias and four dark images will be taken before and after the annealing procedure for both WFC and HRC.The HRC darks are taken in parallel with the WFC darks.The charge transfer efficiency {CTE} of the ACS CCD detectors declinesas damage due to on-orbit radiation exposure accumulates. This degradationhas been closely monitored at regular intervals, because it is likely todetermine the useful lifetime of the CCDs.We combine the annealling activity with the charge transfer efficiency monitoring and also merge into the routine dark image collection. To this end, the CTE monitoring exposures have been moved into this proposal . All the data for this program is acquired using internal targets {lamps} only,so all of the exposures should be taken during Earth occultation time{but not during SAA passages}.This program emulates the ACS pre-flight ground calibration and post-launchSMOV testing {program 8948}, so that results from each epoch can be directlycompared. Extended Pixel Edge Response {EPER} and First Pixel Response {FPR}data will be obtained over a range of signal levels for both theWide Field Channel {WFC}, and the High Resolution Channel {HRC}.

Cox, Colin

2006-07-01

67

CCD Hot Pixel Annealing  

NASA Astrophysics Data System (ADS)

Hot pixel annealing will continue to be performed once every 4 weeks. The CCD TECs will be turned off and heaters will be activated to bring the detector temperatures to about +20C. This state will be held for approximately 12 hours, after which the heaters are turned off, the TECs turned on, and the CCDs returned to normal operating condition. To assess the effectiveness of the annealing, a bias and four dark images will be taken before and after the annealing procedure for both WFC and HRC. The HRC darks are taken in parallel with the WFC darks. The charge transfer efficiency {CTE} of the ACS CCD detectors declines as damage due to on-orbit radiation exposure accumulates. This degradation has been closely monitored at regular intervals, because it is likely to determine the useful lifetime of the CCDs. We will now combine the annealling activity with the charge transfer efficiency monitoring and also merge into the routine dark image collection. To this end, the CTE monitoring exposures have been moved into this proposal . All the data for this program is acquired using internal targets {lamps} only, so all of the exposures should be taken during Earth occultation time {but not during SAA passages}. This program emulates the ACS pre-flight ground calibration and post-launch SMOV testing {program 8948}, so that results from each epoch can be directly compared. Extended Pixel Edge Response {EPER} and First Pixel Response {FPR} data will be obtained over a range of signal levels for both the Wide Field Channel {WFC}, and the High Resolution Channel {HRC}.

Cox, Colin

2004-07-01

68

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

69

Indian Vacuum Society: The Indian Vacuum Society  

NASA Astrophysics Data System (ADS)

The Indian Vacuum Society (IVS) was established in 1970. It has over 800 members including many from Industry and R & D Institutions spread throughout India. The society has an active chapter at Kolkata. The society was formed with the main aim to promote, encourage and develop the growth of Vacuum Science, Techniques and Applications in India. In order to achieve this aim it has conducted a number of short term courses at graduate and technician levels on vacuum science and technology on topics ranging from low vacuum to ultrahigh vacuum So far it has conducted 39 such courses at different parts of the country and imparted training to more than 1200 persons in the field. Some of these courses were in-plant training courses conducted on the premises of the establishment and designed to take care of the special needs of the establishment. IVS also regularly conducts national and international seminars and symposia on vacuum science and technology with special emphasis on some theme related to applications of vacuum. A large number of delegates from all over India take part in the deliberations of such seminars and symposia and present their work. IVS also arranges technical visits to different industries and research institutes. The society also helped in the UNESCO sponsored post-graduate level courses in vacuum science, technology and applications conducted by Mumbai University. The society has also designed a certificate and diploma course for graduate level students studying vacuum science and technology and has submitted a syllabus to the academic council of the University of Mumbai for their approval, we hope that some colleges affiliated to the university will start this course from the coming academic year. IVS extended its support in standardizing many of the vacuum instruments and played a vital role in helping to set up a Regional Testing Centre along with BARC. As part of the development of vacuum education, the society arranges the participation of expert members on the subject to deliver lectures and take part in devising courses in the universities. IVS publishes a quarterly called the `Bulletin of Indian Vacuum Society' since its inception, in which articles on vacuum and related topics are published. NIRVAT, news, announcements, and reports are the other features of the Bulletin. The articles in the Bulletin are internationally abstracted. The Bulletin is distributed free to all the members of the society. The society also publishes proceedings of national/international symposia and seminars, manuals, lecture notes etc. It has published a `Vacuum Directory' containing very useful information on vacuum technology. IVS has also set up its own website http://www.ivsnet.org in January 2002. The website contains information about IVS, list of members, list of EC members, events and news, abstracts of articles published in the `Bulletin of Indian Vacuum Society', utilities, announcements, reports, membership and other forms which can be completed online and also gives links to other vacuum societies. Our Society has been a member of the executive council of the International Union of Vacuum Science, Techniques and Applications (IUVSTA) and its various committees since 1970. In 1983 IVS conducted an International Symposium on Vacuum Technology and Nuclear Applications in BARC, Mumbai, under the sponsorship of IUVSTA. In 1987 IVS arranged the Triennial International Conference on Thin Films in New Delhi, where more than 200 foreign delegates participated. IVS also hosted the IUVSTA Executive Council Meeting along with the conference. The society organized yet again an International Conference on Vacuum Science and Technology and SRS Vacuum Systems at CAT, Indore in1995. IVS arranges the prestigious Professor Balakrishnan Memorial Lecture in memory of its founder vice-president. Leading scientists from India and abroad in the field are invited to deliver the talks. So far 23 lectures have been held in this series. IVS has instituted the `IVS- Professor D Y Phadke Memorial Prize' in memory of our founder presid

Saha, T. K.

2008-03-01

70

Imaging of snapping phenomena  

PubMed Central

Snapping phenomena result from the sudden impingement between anatomical and/or heterotopical structures with subsequent abrupt movement and noise. Snaps are variously perceived by patients, from mild discomfort to significant pain requiring surgical management. Identifying the precise cause of snaps may be challenging when no abnormality is encountered on routinely performed static examinations. In this regard, dynamic imaging techniques have been developed over time, with various degrees of success. This review encompasses the main features of each imaging technique and proposes an overview of the main snapping phenomena in the musculoskeletal system. PMID:22744321

Guillin, R; Marchand, A J; Roux, A; Niederberger, E; Duvauferrier, R

2012-01-01

71

Wave Phenomena Simulations  

NSDL National Science Digital Library

This resource contains interactive wave motion simulations for students in introductory physics classes. The various simulations model phenomena such as wave superposition, reflection, and refraction, as well as the interference of waves, the Doppler effect, the superposition of sine waves, and the various intensities of spherical waves.

Taylor, Barney

2003-10-10

72

Transport phenomena in nanofluidics  

Microsoft Academic Search

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

Reto B. Schoch; Jongyoon Han; Philippe Renaud

2008-01-01

73

Solar cosmic ray phenomena  

Microsoft Academic Search

This review attempts to present an integrated view of the several types of solar cosmic ray phenomena. The relevant large and small scale properties of the interplanetary medium are first surveyed, and their use in the development of a quantitative understanding of the cosmic ray propagation processes summarised. Solar cosmic ray events, in general, are classified into two phenomenological categories:

K. G. McCracken; U. R. Rao

1970-01-01

74

Educational Vacuum Trainers  

NSDL National Science Digital Library

Have you inherited a bell jar vacuum system and are scratching your head over how to set it up or are unsure of its operations or capabilities? Or do you want to do more with your bell jar vacuum? The forum on Bell Jar Vacuums - with the topic Vacuum Trainers can help you. The intent of this forum is for this to be a place where technical issues, classroom exercises, activities, etc. can be discussed. There's no endorsement by manufacturers and commercial issues are off limits. Steve Hansen (bell jar expert) gives some brief descriptions of the vacuum trainers that are or have been available over the past decade or so - Varian, MKS, Science Source, American Vacuum Society. Links are provided to various data sheets, articles and online exercises. Steve, the forum moderator has experience in all of these.Keywords: vacuum, "vacuum trainer","bell jar" and/or belljar, MKSVarian, VPAL, VTS, sputtering, plasma

Hansen, Steve

2012-07-31

75

Effect of Post Annealing in Various Atmospheric Environment Applied to ZnO:Ga Films  

Microsoft Academic Search

In this study, transparent conductive films (TCO) of ZnO:Ga (GZO) were deposited by facing target sputtering to explore the effect of post-annealing on the structural, electrical and optical properties of the films. As deposited films have been annealed to each different temperature condition in various atmosphere environments (air, N2, Vacuum N2). In the result, in air atmosphere condition, ZnO:Ga films

Kyu-Ho Lee; Chung Wung Bark; Hyung-Wook Choi; Kyung Hwan Kim

2012-01-01

76

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.

77

Stainless Steel Vacuum Chambers  

Microsoft Academic Search

The vacuum properties of stainless steel are excellent. The fabrication and welding process can be handled easily by a large number of vacuum manufacturers. In particular, the use for intermediate energy light sources gives a lot of advantages, which leads to a cost effective and industrial vacuum system design. Several design solutions are compared in this paper. The common fabrication

Lothar Schulz

78

Some nonlinear optical phenomena  

NASA Astrophysics Data System (ADS)

Some nonlinear optical phenomena are investigated, especially stimulated scattering, from the point of view of the kinetic theory of radiation (i.e., photon transport theory). Kinetic theory provides a perspective, different from Maxwell's wave theory, from which an examination of these complex matters may proceed with some advantages: (i) considerable mathematical simplication in some instances, (ii) clear and natural separation of microscopic versus macroscopic nonlinearities, (iii) kinetic theory couples the radition field nonlinearly to a formally exact description of the matter field, and (iv) it is believed that the mathematical model provided by kinetic theory is perhaps better suited for numerical studies of the effect of diverse nonlinear optical phenomena upon laser-fusion implosion dynamics than Maxwell's wave theory. Although the main emphasis is upon stimulated scattering, the incorporation of other nonlinearities into the kinetic model is discussed briefly.

Hammouda, Boualem; Osborn, Richard K.

1981-09-01

79

Lunar transient phenomena  

NASA Astrophysics Data System (ADS)

Lunar transient phenomena (LTP) sightings are classified into five categories: brightenings, darkenings, reddish colorations, bluish colorations, and obscurations. There is evidence that the remaining LTP's are of lunar origin. A substantial number of sightings are independently confirmed. They have been recorded on film and spectrograms, as well as with photoelectric photometers and polarization equipment. It suggested that the LTP's may be gentle outgassings of less-than-volcanic proportions.

Cameron, W. S.

1991-03-01

80

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

81

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

82

Electron-irradiation enhanced photoluminescence from GaInNAs /GaAs quantum wells subject to thermal annealing  

NASA Astrophysics Data System (ADS)

Electron irradiation of a 1.3-?m-GaInNAs/GaAs multi-quantum-well heterostructure, grown by molecular beam epitaxy and subsequently rapid-thermal annealed, is found to induce much stronger photoluminescence than what is observed for an identical as-grown sample upon annealing. Annealing of the irradiated sample also causes a small additional spectral blueshift and reduces alloy potential energy fluctuations at the conduction band minimum. These irradiation-related phenomena are accompanied by small but discernable changes in x-ray diffraction features upon annealing, which indicate compositional and/or structural changes in the quantum wells.

Pavelescu, E.-M.; Gheorghiu, A.; Dumitrescu, M.; Tukiainen, A.; Jouhti, T.; Hakkarainen, T.; Kudrawiec, R.; Andrzejewski, J.; Misiewicz, J.; Tkachenko, N.; Dhaka, V. D. S.; Lemmetyinen, H.; Pessa, M.

2004-12-01

83

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

84

Space vacuum processing  

NASA Technical Reports Server (NTRS)

The unique ultra-vacuum environment of low-earth orbit space is to be utilized for vacuum processing of advanced semiconductor and superconductor materials through epitaxial thin-film growth. The quality of semiconductor single crystal (epitaxial) thin-films can be significantly enhanced in the space ultra-vacuum through the reduction of impurities. This will be accomplished by the development of the free-flying Wake Shield Facility presently being built by the Space Vacuum Epitaxy Center in conjunction with industry and NASA under a low-cost, short time commercial approach to space hardware development.

Ignatiev, A.; Shih, H. D.; Daniels, M.; Sega, R.; Bonner, T.

1991-01-01

85

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

86

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

87

Breakdown phenomena in high power klystrons  

SciTech Connect

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. 9 refs., 5 figs., 3 tabs.

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

1988-03-01

88

Effect of annealing ambient on the structural, optical and electrical properties of (Mg,Al)-codoped ZnO thin films  

NASA Astrophysics Data System (ADS)

Nominal 1?at.% Al-doped Zn1-xMgxO (x=0-8?at.%) thin films are prepared by the sol-gel method. The codoping films retain the hexagonal wurtzite structure of ZnO, and show preferential c-axis orientation. The effect of annealing ambient (in vacuum and nitrogen) on the optical and electrical properties of (Mg,Al)-codoped ZnO films is investigated. The transmittance of the codoping films is obviously degraded to 50-60% by vacuum annealing, but is enhanced to 70-80% after nitrogen annealing. Both the carrier concentration and the Hall mobility decrease, and the resistivity increases with the widening of the band gap in films treated in vacuum. However, the carrier concentration of films annealed in nitrogen displays fluctuations with increasing x, and the carrier concentrations of films with x=2 and 4% are higher than those of other films. The initial band gap increase of nitrogen-annealed films might be attributed both to Mg doping and to the Burstein-Moss effect due to the NO-(N2)O complex donors. In view of the transmittance and conductivity, nitrogen annealing might be a more appropriate post-annealing method than vacuum annealing for (Mg,Al)-codoped ZnO films to fulfil the requirements of transparent conducting oxide.

Duan, L. B.; Zhao, X. R.; Liu, J. M.; Geng, W. C.; Xie, H. Y.; Sun, H. N.

2012-03-01

89

Morphology change of oxygen-restructured TiO2,,110... surfaces by UHV annealing: Formation of a low-temperature ,,12... structure  

E-print Network

Morphology change of oxygen-restructured TiO2,,110... surfaces by UHV annealing: Formation of a low-temperature are oxidized at moderate temperatures 470­660 K , the surfaces restructure. Interstitial Ti atoms from the bulk. Restructured surfaces are annealed in ul- trahigh vacuum UHV at temperatures between 620 and 830 K. The surface

Diebold, Ulrike

90

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

91

Crystallization phenomena in slags  

NASA Astrophysics Data System (ADS)

The crystallization of the mold slag affects both the heat transfer and the lubrication between the mold and the strand in continuous casting of steel. In order for mold slag design to become an engineering science rather than an empirical exercise, a fundamental understanding of the melting and solidification behavior of a slag must be developed. Thus it is necessary to be able to quantify the phenomena that occur under the thermal conditions that are found in the mold of a continuous caster. The double hot thermocouple technique (DHTT) and the Confocal Laser Scanning Microscope used in this study are two novel techniques for investigating melting and solidification phenomena of transparent slags. Results from these techniques are useful in defining the phenomena that occur when the slag film infiltrates between the mold and the shell of the casting. TTT diagrams were obtained for various slags and indicated that the onset of crystallization is a function of cooling rate and slag chemistry. Crystal morphology was found to be dependent upon the experimental temperature and four different morphologies were classified based upon the degree of melt undercooling. Continuous cooling experiments were carried out to develop CCT diagrams and it was found that the amount and appearance of the crystalline fraction greatly depends on the cooling conditions. The DHTT can also be used to mimic the cooling profile encountered by the slag in the mold of a continuous caster. In this differential cooling mode (DCT), it was found that the details of the cooling rate determine the actual response of the slag to a thermal gradient and small changes can lead to significantly different results. Crystal growth rates were measured and found to be in the range between 0.11 mum/s to 11.73 mum/s depending on temperature and slag chemistry. Alumina particles were found to be effective innoculants in oxide melts reducing the incubation time for the onset of crystallization and also extending the temperature range of observed crystallization. The effect of changing the gas atmosphere surrounding the sample has been studied. The presence of water vapor increased the nucleation rate and crystal growth rate significantly when compared to experiments carried out in a dry atmosphere. With an atmosphere of Argon and Argon-3% Hydrogen mixture, the incubation time for crystallization was increased with several minutes. The crystal growth rate in these atmospheres was also drastically reduced compared to an atmosphere of normal air. Significant numbers of bubbles were formed during the initial melting of mold slag samples and the melting rate of the slag was found to be related to the rate of bubble generation and to the rate of heat transport.

Orrling, Carl Folke

2000-09-01

92

Reactor vessel annealing system  

DOEpatents

A system for annealing a vessel (14) in situ by heating the vessel (14) to a defined temperature, composed of: an electrically operated heater assembly (10) insertable into the vessel (14) for heating the vessel (14) to the defined temperature; temperature monitoring components positioned relative to the heater assembly (10) for monitoring the temperature of the vessel (14); a controllable electric power supply unit (32-60) for supplying electric power required by the heater assembly (10); a control unit (80-86) for controlling the power supplied by the power supply unit (32-60); a first vehicle (2) containing the power supply unit (32-60); a second vehicle (4) containing the control unit (80-86); power conductors (18,22) connectable between the power supply unit (32-60) and the heater unit (10) for delivering the power supplied by the power supply unit (32-60) to the heater assembly (10); signal conductors (20,24) connectable between the temperature monitoring components and the control unit (80-86) for delivering temperature indicating signals from the temperature monitoring components to the control unit (80-86); and control conductors (8) connectable between the control unit (80-86) and the power supply unit (32-60) for delivering to the power supply unit (32-60) control signals for controlling the level of power supplied by the power supply unit (32-60) to the heater assembly (10).

Miller, Phillip E. (Greensburg, PA); Katz, Leonoard R. (Pittsburgh, PA); Nath, Raymond J. (Murrysville, PA); Blaushild, Ronald M. (Export, PA); Tatch, Michael D. (Randolph, NJ); Kordalski, Frank J. (White Oak, PA); Wykstra, Donald T. (Pittsburgh, PA); Kavalkovich, William M. (Monroeville, PA)

1991-01-01

93

Shock wave reflection phenomena  

NASA Astrophysics Data System (ADS)

The present publication encompasses shock-wave reflection phenomena in a review of their phenomenological aspects in a range of flow types. Oblique shock-wave reflections are analyzed by means of expressions from the two- and three-shock theories with illustrations of the transition boundaries from regular and Mach reflection. Shock-wave reflection is further reviewed for such cases as unsteady, steady, and pseudosteady flows with criteria for the formation and termination of these reflection cases. Experimental results are compared to analytical predictions, and the governing equations are treated with additional expressions and modifications that describe viscous and real gas effects. It is expected that the work in this volume can lead to the development of numerical codes for the prediction of regular reflection as well as single- and double-Mach reflection.

Ben-Dor, Gabi

94

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

95

Vacuum control valve  

Microsoft Academic Search

A vacuum modulating chamber of a vacuum control valve is communicated with a diaphragm chamber of a EGR valve for controlling an amount of exhaust gas to be recirculated into combustion chambers of an engine, so that a modulated negative pressure is applied thereto. The chamber is provided with a diaphragm deflected responding to the negative pressure in the chamber.

M. Naito; K. Itou; K. Tsuzuki; K. Yano

1984-01-01

96

Working in a Vacuum  

ERIC Educational Resources Information Center

In this article, the author discusses several myths about vacuum cleaners and offers tips on evaluating and purchasing this essential maintenance tool. These myths are: (1) Amps mean performance; (2) Everyone needs high-efficiency particulate air (HEPA): (3) Picking up a "bowling ball" shows cleaning power; (4) All vacuum bags are the same; (5)…

Rathey, Allen

2005-01-01

97

Vacuum pump aids ejectors  

Microsoft Academic Search

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

1982-01-01

98

Vacuum Energy Decay  

E-print Network

The problem of the vacuum energy decay is studied through the analysis of the vacuum survival amplitude ${\\mathcal A}(z, z')$. Transition amplitudes are computed for finite time-span, $Z\\equiv z^\\prime-z$, and their {\\em late time} behavior is discussed up to first order in the coupling constant, $\\l$.

Enrique Álvarez; Roberto Vidal

2011-11-09

99

Stellarator helical vacuum vessel  

Microsoft Academic Search

A design study of a stainless steel, heavy wall, helically shaped vacuum torus has been made for use in a proposed Stellarator configuration. The study concerns itself with the shape of the vacuum vessel and the division of the vessel into components that can be machined and welded together into a helical configuration. A complication in the design requires that

Yavornik

1983-01-01

100

Annealing Behaviour of Hydrogenated and Oxidized Nanocrystalline Diamond  

NASA Astrophysics Data System (ADS)

Hydrogenated and oxidized nanocrystalline diamond (NCD) is a very promising material for future electronic, especially bioelectronic applications. In the past it has been shown that hydrogen, oxygen, and gases from the ambient environment as well as water can be responsible for causing drastic changes in surface conductivity and wettability (hydrophobicity, hydrophilicity), friction, wear, etc. In this contribution we have investigated differently prepared NCDs as function of the annealing temperature under ultrahigh vacuum conditions (UHV) with various electron spectroscopies like UPS and XPS as well as High Resolution Electron Energy Loss Spectroscopy (HREELS). We were able to identify the thermal stability of a number of different species at the interface, which are related to different characteristics of C-H, O-H, C-O, and C-C bonding. Finally, a carbonization of the interface appeared at higher annealing temperatures.

Schaefer, J. A.; Neumann, A.; Uhlig, J.; Finsterbusch, M.; Eremtchenko, M.; Ahmed, S. I.-U.; Garrido, J. A.; Stutzmann, M.

2007-03-01

101

Quantum annealing with manufactured spins.  

PubMed

Many interesting but practically intractable problems can be reduced to that of finding the ground state of a system of interacting spins; however, finding such a ground state remains computationally difficult. It is believed that the ground state of some naturally occurring spin systems can be effectively attained through a process called quantum annealing. If it could be harnessed, quantum annealing might improve on known methods for solving certain types of problem. However, physical investigation of quantum annealing has been largely confined to microscopic spins in condensed-matter systems. Here we use quantum annealing to find the ground state of an artificial Ising spin system comprising an array of eight superconducting flux quantum bits with programmable spin-spin couplings. We observe a clear signature of quantum annealing, distinguishable from classical thermal annealing through the temperature dependence of the time at which the system dynamics freezes. Our implementation can be configured in situ to realize a wide variety of different spin networks, each of which can be monitored as it moves towards a low-energy configuration. This programmable artificial spin network bridges the gap between the theoretical study of ideal isolated spin networks and the experimental investigation of bulk magnetic samples. Moreover, with an increased number of spins, such a system may provide a practical physical means to implement a quantum algorithm, possibly allowing more-effective approaches to solving certain classes of hard combinatorial optimization problems. PMID:21562559

Johnson, M W; Amin, M H S; Gildert, S; Lanting, T; Hamze, F; Dickson, N; Harris, R; Berkley, A J; Johansson, J; Bunyk, P; Chapple, E M; Enderud, C; Hilton, J P; Karimi, K; Ladizinsky, E; Ladizinsky, N; Oh, T; Perminov, I; Rich, C; Thom, M C; Tolkacheva, E; Truncik, C J S; Uchaikin, S; Wang, J; Wilson, B; Rose, G

2011-05-12

102

Linear response theory for annealing of radiation damage in semiconductor devices. Summary report  

SciTech Connect

A theoretical study of the radiation/annealing response of MOS ICs is described. Although many experiments have been performed in this field, no comprehensive theory dealing with radiation/annealing response has been proposed. Many attempts have been made to apply linear response theory, but no theoretical foundation has been presented. The linear response theory outlined here is capable of describing a broad area of radiation/annealing response phenomena in MOS ICs, in particular, both simultaneous irradiation and annealing, as well as short- and long-term annealing, including the case when annealing is nearing completion. For the first time, a simple procedure is devised to determine the response function from experimental radiation/annealing data. In addition, this procedure enables us to study the effect of variable temperature and dose rate, effects which are of interest in spaceflight. In the past, the shift in threshold potential due to radiation/annealing has usually been assumed to depend on one variable: the time lapse between an impulse dose and the time of observation. While such a suggestion of uniformity in time is certainly true for a broad range of radiation annealing phenomena, it may not hold for some ranges of the variables of interest (temperature, dose rate, etc.). A response function is projected which is dependent on two variables: the time of observation and the time of the impulse dose. This dependence on two variables allows us to extend the theory to the treatment of a variable dose rate. Finally, the linear theory is generalized to the case in which the response is nonlinear with impulse dose, but is proportional to some impulse function of dose. A method to determine both the impulse and response functions is presented.

Litovchenko, V.

1988-12-01

103

ON DETECTING TRANSIENT PHENOMENA  

SciTech Connect

Transient phenomena are interesting and potentially highly revealing of details about the processes under observation and study that could otherwise go unnoticed. It is therefore important to maximize the sensitivity of the method used to identify such events. In this article, we present a general procedure based on the use of the likelihood function for identifying transients which is particularly suited for real-time applications because it requires no grouping or pre-processing of the data. The method makes use of all the information that is available in the data throughout the statistical decision-making process, and is suitable for a wide range of applications. Here we consider those most common in astrophysics, which involve searching for transient sources, events or features in images, time series, energy spectra, and power spectra, and demonstrate the use of the method in the case of a weak X-ray flare in a time series and a short-lived quasi-periodic oscillation in a power spectrum. We derive a fit statistic that is ideal for fitting arbitrarily shaped models to a power density distribution, which is of general interest in all applications involving periodogram analysis.

Belanger, G., E-mail: gbelanger@sciops.esa.int [European Space Astronomy Centre (ESA/ESAC), Science Operations Department, Villanueva de la Canada (Madrid) (Spain)

2013-08-10

104

Vacuum-driven Metamorphosis  

E-print Network

We show that nonperturbative vacuum effects can produce a vacuum-driven transition from a matter-dominated universe to one in which the effective equation of state is that of radiation plus cosmological constant. The actual material content of the universe after the transition remains that of non-relativistic matter. This metamorphosis of the equation of state can be traced to nonperturbative vacuum effects that cause the scalar curvature to remain nearly constant at a well-defined value after the transition, and is responsible for the observed acceleration of the recent expansion of the universe.

Parker, L; Parker, Leonard; Raval, Alpan

1999-01-01

105

Vacuum-driven Metamorphosis  

E-print Network

We show that nonperturbative vacuum effects can produce a vacuum-driven transition from a matter-dominated universe to one in which the effective equation of state is that of radiation plus cosmological constant. The actual material content of the universe after the transition remains that of non-relativistic matter. This metamorphosis of the equation of state can be traced to nonperturbative vacuum effects that cause the scalar curvature to remain nearly constant at a well-defined value after the transition, and is responsible for the observed acceleration of the recent expansion of the universe.

Leonard Parker; Alpan Raval

1999-08-26

106

Collapse of Vacuum Bubbles in a Vacuum  

E-print Network

Motivated by the discovery of a plenitude of metastable vacua in a string landscape and the possibility of rapid tunneling between these vacua, we revisit the dynamics of a false vacuum bubble in a background de Sitter spacetime. We find that there exists a large parameter space that allows the bubble to collapse into a black hole or to form a wormhole. This may have interesting implications to inflationary physics.

Kin-Wang Ng; Shang-Yung Wang

2010-06-17

107

Annealing and Test Temperature Dependence of Tensile Properties of UNS N04400 Alloy  

NASA Astrophysics Data System (ADS)

Effects of annealing and test temperatures on the tensile behavior of UNS N04400 alloy have been examined. The specimens were annealed at 800, 1000, and 1200 °C for 4 h under vacuum in a muffle furnace. Stress-strain curves of the specimens were obtained in the temperature range 25-300 °C using a universal testing machine fitted with a thermostatic chamber. The results indicate that the yield strength (YS), ultimate tensile strength (UTS), and percentage elongation of the specimens decrease with increase of annealing temperature. By increasing the test temperature, the YS and UTS decrease, whereas the percentage elongation initially decreases with increase of test temperature from 25 to 100 °C and then increases with further increasing the temperature up to 300 °C. The changes in the tensile properties of the alloy are associated with the post-annealing microstructure and modes of fracture.

Afzal, Naveed; Ahmad, R.; Akhtar, Tanveer; Ayub, R.; Ghauri, I. M.

2013-07-01

108

Origin of New Broad Raman D and G Peaks in Annealed Graphene  

PubMed Central

Since graphene, a single sheet of graphite, has all of its carbon atoms on the surface, its property is very sensitive to materials contacting the surface. Herein, we report novel Raman peaks observed in annealed graphene and elucidate their chemical origins by Raman spectroscopy and atomic force microscopy (AFM). Graphene annealed in oxygen-free atmosphere revealed very broad additional Raman peaks overlapping the D, G and 2D peaks of graphene itself. Based on the topographic confirmation by AFM, the new Raman peaks were attributed to amorphous carbon formed on the surface of graphene by carbonization of environmental hydrocarbons. While the carbonaceous layers were formed for a wide range of annealing temperature and time, they could be effectively removed by prolonged annealing in vacuum. This study underlines that spectral features of graphene and presumably other 2-dimensional materials are highly vulnerable to interference by foreign materials of molecular thickness. PMID:24048447

Hong, Jinpyo; Park, Min Kyu; Lee, Eun Jung; Lee, DaeEung; Hwang, Dong Seok; Ryu, Sunmin

2013-01-01

109

Three-dimensional transient temperature field model for laser annealing  

SciTech Connect

A three-dimensional transient temperature field model (TTFM) is proposed for the general problem of laser-induced out-of-equilibrium annealing of a bilayer device, which is made up of a bulk material covered by a transparent layer. The TTFM solves the moving-boundary problem with a deterministic relation between the interface velocity and temperature in contrast to preceding problem-dependent models, which use an interface-tracking heuristic algorithm. The TTFM is the first step to model many temperature-driven phenomena such as diffusion and segregation in laser annealing. Both computed transient temperature field and melted-zone dimensions of a SiO{sub 2}/Si example device, which is irradiated by a focused visible (532 nm) laser, are in very good agreement with experimental measurements.

Degorce, Jean-Yves; Gillet, Jean-Numa; Magny, Francois; Meunier, Michel [Department of Engineering Physics, Ecole Polytechnique de Montreal, Laser Processing Laboratory, C.P. 6079, succ. Centre-ville, Montreal, Quebec H3C 3A7 (Canada)

2005-02-01

110

Welding space vacuum technology  

NASA Technical Reports Server (NTRS)

The objective was to assist the EH 42 Division in putting together a vacuum system that could attain the desired pressure and be large enough to accommodate the gas-metal arc (GMA) welding fixture apparatus. A major accomplishment was the design and fabrication of the controller/annunciator for the 4' by 8' system. It contains many safety features such as thermocouple set point relays that will only allow inlet and exit gas and vacuum valves to be operated at pre-selected system pressures, and a fail safe mode for power interruptions and operator mistakes. It is felt that significant progress was made in this research effort to weld in a vacuum environment. With continued efforts to increase the pump speeds for vacuum chambers and further studies on weld fixtures and gas inlet pressures, the NASA program will be successful.

Johnson, R. Barry

1991-01-01

111

Welding space vacuum technology  

NASA Astrophysics Data System (ADS)

The objective was to assist the EH 42 Division in putting together a vacuum system that could attain the desired pressure and be large enough to accommodate the gas-metal arc (GMA) welding fixture apparatus. A major accomplishment was the design and fabrication of the controller/annunciator for the 4' by 8' system. It contains many safety features such as thermocouple set point relays that will only allow inlet and exit gas and vacuum valves to be operated at pre-selected system pressures, and a fail safe mode for power interruptions and operator mistakes. It is felt that significant progress was made in this research effort to weld in a vacuum environment. With continued efforts to increase the pump speeds for vacuum chambers and further studies on weld fixtures and gas inlet pressures, the NASA program will be successful.

Johnson, R. Barry

1991-12-01

112

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

113

Vacuum control valve  

SciTech Connect

A vacuum modulating chamber of a vacuum control valve is communicated with a diaphragm chamber of a EGR valve for controlling an amount of exhaust gas to be recirculated into combustion chambers of an engine, so that a modulated negative pressure is applied thereto. The chamber is provided with a diaphragm deflected responding to the negative pressure in the chamber. The vacuum control valve is further provided with a cam member and a spring which urges the diaphragm in one direction so as to change a value at which the pressure in the vacuum modulating chamber is controlled. A push rod is movably held by a cam follower and another spring is provided for urging the push rod in the above direction. The spring force of the other spring is applied to the diaphragm, when a rotational angle of the cam member exceeds a predetermined angle, so that the negative pressure is changed rapidly.

Naito, M.; Itou, K.; Tsuzuki, K.; Yano, K.

1984-04-03

114

Vacuum Boundary Effects  

E-print Network

The effect of boundary conditions on the vacuum structure of quantum field theories is analysed from a quantum information viewpoint. In particular, we analyse the role of boundary conditions on boundary entropy and entanglement entropy. The analysis of boundary effects on massless free field theories points out the relevance of boundary conditions as a new rich source of information about the vacuum structure. In all cases the entropy does not increase along the flow from the ultraviolet to the infrared.

M. Asorey; J. M. Munoz-Castaneda

2008-03-18

115

Vacuum self-magnetization?  

SciTech Connect

We study vacuum properties in a strong magnetic field as the zero temperature and zero density limit of quantum statistics. For charged vector bosons (W bosons) the vacuum energy density diverges for B > B{sub c} = m{sub w}{sup 2}/e, leading to vacuum instability. A logarithmic divergence of vacuum magnetization is found for B = Bc, which suggests that if the magnetic field is large enough, it is self-consistently maintained, and this mechanism actually prevents B from reaching the critical value Bc. For virtual neutral vector bosons bearing an anomalous magnetic moment, the instability of the ground state for B > B{sub c}{sup '} = m{sub n}{sup 2}/q also leads to the vacuum energy density divergence for fields B > B{sub c}{sup '} and to the magnetization divergence for B B{sub c}{sup '}. The possibility of virtual electron-positron pairs bosonization in strong magnetic field and the applicability of the neutral bosons model to describe the virtual positronium behavior in a magnetic field are discussed. We conjecture that this could lead to vacuum self-magnetization in QED.

Perez Rojas, H.; Rodriguez Querts, E. [Instituto de Cibernetica, Matematica y Fisica, Calle E No. 309, esq. a 15 Vedado, C. Havana (Cuba)

2006-06-19

116

Teaching undergraduate nurses nursing phenomena.  

PubMed

Nursing phenomena, complex and dynamic conceptual building blocks, are the basis of our nursing language. Students have difficulty understanding what nursing phenomena are and how to link them to practice and research. The authors describe incremental experiential learning strategies that were used to help students learn and apply the basic concepts of their nursing language. PMID:20010266

Hemman, Eileen A; Fought, Sharon Gavin

2010-01-01

117

Electromagnetic vacuum of complex media: Dipole emission versus light propagation, vacuum energy, and local field factors  

SciTech Connect

We offer a unified approach to several phenomena related to the electromagnetic vacuum of a complex medium made of point electric dipoles. To this aim, we apply the linear response theory to the computation of the polarization field propagator and study the spectrum of vacuum fluctuations. The physical distinction among the local density of states which enter the spectra of light propagation, total dipole emission, coherent emission, total vacuum energy, and Schwinger-bulk energy is made clear. Analytical expressions for the spectrum of dipole emission and for the vacuum energy are derived. Their respective relations with the spectrum of external light and with the Schwinger-bulk energy are found. The light spectrum and the Schwinger-bulk energy are determined by the Dyson propagator. The emission spectrum and the total vacuum energy are determined by the polarization propagator. An exact relationship of proportionality between both propagators is found in terms of local field factors. A study of the nature of stimulated emission from a single dipole is carried out. Regarding coherent emission, it contains two components. A direct one which is transferred radiatively and directly from the emitter into the medium and whose spectrum is that of external light. And an indirect one which is radiated by induced dipoles. The induction is mediated by one (and only one) local field factor. Regarding the vacuum energy, we find that in addition to the Schwinger-bulk energy the vacuum energy of an effective medium contains local field contributions proportional to the resonant frequency and to the spectral line width.

Donaire, M. [Centro de Fisica do Porto, Faculdade de Ciencias da Universidade do Porto, Rua do Campo Alegre 687, P-4169-007 Porto (Portugal); Departamento de Fisica de la Materia Condensada, Universidad Autonoma de Madrid, E-28049 Madrid (Spain)

2011-02-15

118

Influence of thermal annealing and ultraviolet light irradiation on LaF3 thin films at 193 nm  

NASA Astrophysics Data System (ADS)

Lanthanum fluoride (LaF3) thin films were prepared by resistive heating evaporation and electron-beam gun evaporation under the same deposition rate, deposition substrate temperature, and vacuum pressure. The coated LaF3 films were then treated by heat annealing and UV light irradiation. The optical properties, microstructures, stress, and laser-induced damage threshold (LIDT) at a wavelength of 193 nm were investigated. The surface roughness, optical loss, stress, and LIDT of the films were improved after the annealing. The films had better properties when irradiated by UV light as compared with heat annealing.

Lee, Cheng-Chung; Liu, Ming-Chung; Kaneko, Masaaki; Nakahira, Kazuhide; Takano, Yuuichi

2005-11-01

119

Influence of thermal annealing and ultraviolet light irradiation on LaF3 thin films at 193 nm.  

PubMed

Lanthanum fluoride (LaF3) thin films were prepared by resistive heating evaporation and electron-beam gun evaporation under the same deposition rate, deposition substrate temperature, and vacuum pressure. The coated LaF3 films were then treated by heat annealing and UV light irradiation. The optical properties, microstructures, stress, and laser-induced damage threshold (LIDT) at a wavelength of 193 nm were investigated. The surface roughness, optical loss, stress, and LIDT of the films were improved after the annealing. The films had better properties when irradiated by UV light as compared with heat annealing. PMID:16294967

Lee, Cheng-Chung; Liu, Ming-Chung; Kaneko, Masaaki; Nakahira, Kazuhide; Takano, Yuuichi

2005-11-10

120

Transient Phenomena on ZT-40.  

National Technical Information Service (NTIS)

Two aspects of fluctuations in the ZT-40 reversed-field pinch are examined. First, the polarization of the magnetic fluctuations in the outer (vacuum) region is discussed. This in turn provides information on the wavevectors associated with the turbulence...

A. R. Jacobson, C. J. Buchenauer

1980-01-01

121

Annealing studies of amorphous alloys  

SciTech Connect

Amorphous films of the alloys Ni-Nb, Ni-Mo, Mo-Si, and W-Si were sputter deposited on single-crystal semiconductor substrates. One-hour crystallization temperatures of the films were determined to within +-25/sup 0/C by annealing and x-ray diffraction measurements. Interdiffusion between Au or Cu overlayers and the amorphous films were studied by annealing combined with Auger Electron Spectroscopy (AES) profiling, and by Rutherford Backscatter (RBS) analysis. Supplementary measurements used to study structural relaxation and crystallization included resistivity as a function of temperature; DTA and DSC; and electron microscopy.

Wiley, J.D.; Perepezko, J.H.; Nordman, J.E.

1983-04-01

122

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

123

Improvement of optical properties of Nd:YAG transparent ceramics by post-annealing and post hot isostatic pressing  

NASA Astrophysics Data System (ADS)

The Nd:YAG transparent ceramics were fabricated by vacuum sintering. The Nd:YAG samples were annealed at 1450 °C for 20 h in air and followed by hot isostatic pressing (HIP) at 1700 °C for 2 h in 200 MPa Ar and then re-annealed at 1250-1450 °C for 10 h in air. The experimental results showed that the optical properties of Nd:YAG samples varied markedly with different post treatments. After air annealing at 1450 °C for 20 h and HIP at 1700 °C for 2 h under 200 MPa of Ar and then air re-annealing at 1250 °C for 10 h, the transmittances of the samples increased from 51.2% to 77.2% (at 400 nm) and 78.4% to 83.6% (at 1064 nm), respectively. The annealing and HIP are effective post treatments to reduce oxygen vacancies and intergranular pores respectively in Nd:YAG transparent ceramics.

Zhang, Wei; Lu, Tiecheng; Ma, Benyuan; Wei, Nian; Lu, Zhongwen; Li, Feng; Guan, Yongbing; Chen, Xingtao; Liu, Wei; Qi, Lu

2013-10-01

124

Stellarator helical vacuum vessel  

SciTech Connect

A design study of a stainless steel, heavy wall, helically shaped vacuum torus has been made for use in a proposed Stellarator configuration. The study concerns itself with the shape of the vacuum vessel and the division of the vessel into components that can be machined and welded together into a helical configuration. A complication in the design requires that a circular magnet coil be located at the minor toroidal axis and that this coil be embedded within the periphery of the vacuum vessel. The vacuum vessel has a minor toroidal axis diameter of 4 meters, a 68.6-cm shell diameter, and a 1.9-cm wall thickness. It twists about the minor toroidal axis twice in 360/sup 0/C. (An n value of 2). It is proposed that the unit be made of cylindrical segments with the ends of the cylinders cut at appropriate lengths and angles to form the helix. A mathematical derivation of the dimensions necessary to produce the required shapes of the segments has been made. Also, drawings of the vacuum vessel components have been produced on LANL's CTR CAD/CAM system. The procedure developed can be used for any value of n as dictated by physics requirements.

Yavornik, E.J.

1983-01-01

125

(Reverse) Engineering Vacuum Alignment  

E-print Network

In the presence of spontaneous symmetry breaking, the alignment of the vacuum with respect to the gauge group is often controlled by quadratically divergent operators in the low energy non-linear sigma model. In principle the magnitudes and signs of these operators can be changed by making different assumptions about the ultraviolet physics, but in practice all known ways of regulating these theories preserve the naive vacuum alignment. We show that by "integrating in" different sets of heavy spin-one fields, it is possible to UV extend certain non-linear sigma models into two distinct UV insensitive theories. These UV extensions have identical low energy degrees of freedom but different radiative potentials, making it possible to engineer two different vacuum alignments for the original non-linear sigma model. Our construction employs "non-square" theory spaces which generically violate the common lore that the preferred vacuum alignment preserves the maximal gauge symmetry. By UV extending the SO(9)/(SO(4) X SO(5)) little Higgs model, we find a radiative potential that deviates from the naive expectation but does not stabilize the correct vacuum for proper electroweak symmetry breaking.

Clifford Cheung; Jesse Thaler

2006-04-28

126

Misconceptions of Emergent Semiconductor Phenomena  

NASA Astrophysics Data System (ADS)

The semiconductor field of Photovoltaics (PV) has experienced tremendous growth, requiring curricula to consider ways to promote student success. One major barrier to success students may face when learning PV is the development of misconceptions. The purpose of this work was to determine the presence and prevalence of misconceptions students may have for three PV semiconductor phenomena; Diffusion, Drift and Excitation. These phenomena are emergent, a class of phenomena that have certain characteristics. In emergent phenomena, the individual entities in the phenomena interact and aggregate to form a self-organizing pattern that can be observed at a higher level. Learners develop a different type of misconception for these phenomena, an emergent misconception. Participants (N=41) completed a written protocol. The pilot study utilized half of these protocols (n = 20) to determine the presence of both general and emergent misconceptions for the three phenomena. Once the presence of both general and emergent misconceptions was confirmed, all protocols (N=41) were analyzed to determine the presence and prevalence of general and emergent misconceptions, and to note any relationships among these misconceptions (full study). Through written protocol analysis of participants' responses, numerous codes emerged from the data for both general and emergent misconceptions. General and emergent misconceptions were found in 80% and 55% of participants' responses, respectively. General misconceptions indicated limited understandings of chemical bonding, electricity and magnetism, energy, and the nature of science. Participants also described the phenomena using teleological, predictable, and causal traits, indicating participants had misconceptions regarding the emergent aspects of the phenomena. For both general and emergent misconceptions, relationships were observed between similar misconceptions within and across the three phenomena, and differences in misconceptions were observed across the phenomena. Overall, the presence and prevalence of both general and emergent misconceptions indicates that learners have limited understandings of the physical and emergent mechanisms for the phenomena. Even though additional work is required, the identification of specific misconceptions can be utilized to enhance semiconductor and PV course content. Specifically, changes can be made to curriculum in order to limit the formation of misconceptions as well as promote conceptual change.

Nelson, Katherine G.

127

Recreation of Natural Optical Phenomena  

NASA Astrophysics Data System (ADS)

This project was undertaken to study and fully understand optical atmospheric phenomena. Research was done on the structure and formation of colorful atmospheric phenomena including, but not limited to, primary, secondary, and supernumerary rainbows, halos, parhelia, and glories. This study also undertakes an attempt to create some of these phenomena. Using hand-made epoxy crystals for ice, a round bottom flask as a water droplet, and a high-powered halogen lamp for sunlight, primary, secondary, and supernumerary rainbows and halos were created and photographed.

Paonessa, Tiffany; Sheldon, Peter

2009-03-01

128

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

129

Acceleration and vacuum temperature  

NASA Astrophysics Data System (ADS)

The quantum fluctuations of an “accelerated” vacuum state, that is, vacuum fluctuations in the presence of a constant electromagnetic field, can be described by the temperature TM. Considering TM for the gyromagnetic factor g=1 we show that TM(g=1)=TU, where TU is the Unruh temperature experienced by an accelerated observer. We conjecture that both particle production and nonlinear field effects inherent in the Unruh accelerated observer case are described by the case g=1 QED of strong fields. We present rates of particle production for g=0, 1, 2 and show that the case g=1 is experimentally distinguishable from g=0, 2. Therefore, either accelerated observers are distinguishable from accelerated vacuum or there is unexpected modification of the theoretical framework.

Labun, Lance; Rafelski, Johann

2012-08-01

130

Inhomogeneous superconductivity induced by interstitial Fe deintercalation in oxidizing-agent-annealed and HNO3-treated Fe1+y(Te1-xSex)  

NASA Astrophysics Data System (ADS)

We have systematically investigated the effect of annealing on the superconductivity of the iron chalcogenide Fe1+y(Te1-xSex). The atmospheres used for annealing include O2, N2, I2 vapor, air and vacuum. We observed that annealing in O2, I2 and air could enhance the superconductivity of underdoped samples, consistent with the results reported in the literature. Interestingly, we found that annealing in N2 also leads to a superconductivity enhancement, similar to the annealing effects of O2, I2 and air. However, vacuum annealing does not enhance the superconductivity, which indicates that the enhanced superconductivity in O2-, N2- , I2- and air-annealed samples is not due to improved homogeneity. In addition, we treated underdoped samples with nitric acid, which is found to enhance the superconductivity as well. Our analyses of these results support the argument that the superconductivity enhancement, caused either by annealing or nitric acid treatment, originates from the variation of interstitial Fe. The interstitial Fe, which is destructive to superconducting pairing, can be reduced by annealing in oxidation agents or nitric acid treatment. We also find that although N2-, O2- and air-annealed samples exhibit strong superconducting diamagnetism with -4?? ˜ 1 (?, dc magnetic susceptibility) for some samples, their actual superconducting volume fraction probed by specific heat is low, ranging from 10% to 30% for 0.09 < x < 0.3, indicating that the superconductivity suppression remains significant even in annealed samples. The strong diamagnetism is associated with the superconducting shielding effect on the non-superconducting phase. We have also established the phase diagram of the annealed samples and compared it with that of the as-grown samples. The effect of annealing on the interplay between magnetism and superconductivity is discussed.

Hu, J.; Wang, G. C.; Qian, B.; Mao, Z. Q.

2012-08-01

131

Vacuum Arc Ion Sources  

E-print Network

The vacuum arc ion source has evolved into a more or less standard laboratory tool for the production of high-current beams of metal ions, and is now used in a number of different embodiments at many laboratories around the world. Applications include primarily ion implantation for material surface modification research, and good performance has been obtained for the injection of high-current beams of heavy-metal ions, in particular uranium, into particle accelerators. As the use of the source has grown, so also have the operational characteristics been improved in a variety of different ways. Here we review the principles, design, and performance of vacuum arc ion sources.

Brown, I

2014-01-01

132

No energy to be extracted from the vacuum  

NASA Astrophysics Data System (ADS)

A few years ago a hopeful article (Evans 2000 Phys. Scr.61 513-7) appeared in this journal promising that according to its 15 authors' opinion the pending energy crisis could be solved by 'extracting energy from the vacuum'. However, in the past years the energy price has grown to unthinkable heights: a reason for having a look at the promised 'energy from the vacuum' in (Evans 2000). So we shall do so below and shall arrive at a great disappointment: the 15 authors were in error; their vacuum energy stems from a simple flaw of thinking by misinterpreting the well-known Lorenz term of the classical Maxwell gauge theory. Their miraculous conclusion should have made the authors suspicious, that just the Lorenz term should yield a vacuum current. Surely, its a pity that vacuum currents and vacuum energy in (Evans 2000) have their origin merely in a simple flaw of thinking, and all further speculations for a vacuum energy density are in vain. However, better to return to reality. Quote: Abstract of [1]: Great announcements... It is shown that if the Loren(t)z condition is discarded, the Maxwell-Heaviside field equations become the Lehnert equations, indicating the presence of charge density and current density in the vacuum. The Lehnert equations are a subset of the O(3) Yang-Mills field equations. Charge and current density in the vacuum are defined straightforwardly in terms of the vector potential and scalar potential, and are conceptually similar to Maxwell's displacement current, which also occurs in the classical vacuum. A demonstration is made of the existence of a time dependent classical vacuum polarization which appears if the Loren(t)z condition is discarded. Vacuum charge and current appear phenomenologically in the Lehnert equations but fundamentally in the O(3) Yang-Mills theory of classical electrodynamics. The latter also allows for the possibility of the existence of vacuum topological magnetic charge density and topological magnetic current density. Both O(3) and Lehnert equations are superior to the Maxwell-Heaviside equations in being able to describe phenomena not amenable to the latter. In theory, devices can be made to extract the energy associated with vacuum charge and current. A review of a former article in this journal.

Bruhn, Gerhard W.

2006-11-01

133

MAGNETIC PROPERTIES OF UNDULATOR VACUUM CHAMBER MATERIALS FOR THE LINAC COHERENT LIGHT SOURCE  

Microsoft Academic Search

A prototype vacuum chamber is being developed at the Advanced Photon Source (APS) for use in the Linac Coherent Light Source at Stanford Linear Accelerator Center. The chamber will be fabricated from austenite stainless steel that is generally regarded as nonmagnetic in the annealed condition and not attracted significantly by a magnet. However, cold working or welding will change its

Soon-Hong Lee; Isaac Vasserman; Shigemi Sasaki; Dean Walters; Dong-Eon Kim

2005-01-01

134

Vacuum arc deposition devices  

SciTech Connect

The vacuum arc is a high-current, low-voltage electrical discharge which produces a plasma consisting of vaporized and ionized electrode material. In the most common cathodic arc deposition systems, the arc concentrates at minute cathode spots on the cathode surface and the plasma is emitted as a hypersonic jet, with some degree of contamination by molten droplets [known as macroparticles (MPs)] of the cathode material. In vacuum arc deposition systems, the location and motion of the cathode spots are confined to desired surfaces by an applied magnetic field and shields around undesired surfaces. Substrates are mounted on a holder so that they intercept some portion of the plasma jet. The substrate often provides for negative bias to control the energy of depositing ions and heating or cooling to control the substrate temperature. In some systems, a magnetic field is used to guide the plasma around an obstacle which blocks the MPs. These elements are integrated with a deposition chamber, cooling, vacuum gauges and pumps, and power supplies to produce a vacuum arc deposition system.

Boxman, R.L.; Zhitomirsky, V.N. [Electrical Discharge and Plasma Laboratory, Faculty of Engineering, Tel Aviv University, P.O. Box 39040, Tel Aviv 69978 (Israel)

2006-02-15

135

Experiments with Vacuum Tubes  

Microsoft Academic Search

IN my letter published in the last number of NATURE I omitted to say that we have compared vacuum tubes without electrodes with a tube containing water. A tube was filled about nine-tenths full of water and then sealed hermetically. It was then applied to the prime conductor of the electric machine and electrified in the same way as the

J. T. Bottomley

1881-01-01

136

Cryogenic vacuum techniques  

Microsoft Academic Search

A survey is made of the state-of-the-art in cryopumping technologies. Among the aspects of the technology reviewed are: molecular flow in nonisothermal vacuum chambers, diverse methods of cryopumping such as condensation, cryosorption at solid gas condensates, and at porous solids such as molecular sieves and activated charcoal, cryotrapping and cryogettering at metal films. Also covered are calculation of cryopump systems

R. A. Haefer

1981-01-01

137

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

138

Sorption vacuum trap  

NASA Technical Reports Server (NTRS)

Modified sorption trap for use in high vacuum systems contains provisions for online regeneration of sorbent material. Trap is so constructed that it has a number of encapsulated resistance heaters and a valving and pumping device for removing gases from heated sorbing material. Excessive downtime is eliminated with this trap.

Barrington, A. E.; Caruso, A. J.

1970-01-01

139

Vacuum thermal insulation panel  

Microsoft Academic Search

A vacuum thermal insulation panel comprises a pair of laminated plastic and aluminum sheets together with a plastic edge strip sealed to the edges of the sheets so as to define an evacuable volume in which a glass fiber mat is disposed. The insulation panel of the present invention takes advantage of the light-weight, low cost and low thermal conductivity

J. R. Young; R. M. Schreck

1984-01-01

140

Topics in vacuum decay  

NASA Astrophysics Data System (ADS)

If a theory has more than one classically stable vacuum, quantum tunneling and thermal jumps make the transition between the vacua possible. The transition happens through a first order phase transition started by nucleation of a bubble of the new vacuum. The outward pressure of the truer vacuum makes the bubble expand and consequently eat away more of the old phase. In the presence of gravity this phenomenon gets more complicated and meanwhile more interesting. It can potentially have important cosmological consequences. Some aspects of this decay are studied in this thesis. Solutions with different symmetry than the generically used O(4) symmetry are studied and their actions calculated. Vacuum decay in a spatial vector field is studied and novel features like kinky domain walls are presented. The question of stability of vacua in a landscape of potentials is studied and the possible instability in large dimension of fields is shown. Finally a compactification of the Einstein-Maxwell theory is studied which can be a good lab to understand the decay rates in compactification models of arbitrary dimensions.

Masoumi, Ali

141

Langmuir vacuum and superconductivity  

SciTech Connect

It is shown that, in the 'jelly' model of cold electron-ion plasma, the interaction between electrons and the quantum electromagnetic vacuum of Langmuir waves involves plasma superconductivity with an energy gap proportional to the energy of the Langmuir quantum.

Veklenko, B. A. [Russian Academy of Sciences, Joint Institute for High Temperatures (Russian Federation)

2012-06-15

142

Welding space vacuum technology  

Microsoft Academic Search

The objective was to assist the EH 42 Division in putting together a vacuum system that could attain the desired pressure and be large enough to accommodate the gas-metal arc (GMA) welding fixture apparatus. A major accomplishment was the design and fabrication of the controller\\/annunciator for the 4' by 8' system. It contains many safety features such as thermocouple set

R. Barry Johnson

1991-01-01

143

Critical velocity phenomena and the LTP. [Lunar Transient Phenomena  

NASA Technical Reports Server (NTRS)

When the relative velocity between magnetized plasma and neutral gas exceeds a critical value, the gas-plasma interaction is dominated by collective phenomena which rapidly excite and ionize the neutrals. The interaction of the solar wind with a large cloud (between 10 to the 24th and 10 to the 28th power neutrals) vented from the moon should be of this type. Line radiation from such an interaction can yield an apparent lunar surface brightness rivaling reflected sunlight levels over small areas, if the kinetic-energy flow density of the gas is sufficiently high. The aberrated solar-wind flow past the moon would enhance the visibility of such interactions near the lunar sunrise terminator, supporting the statistical studies which indicate that the 'Lunar Transient Phenomena' (anomalous optical phenomena on the moon) are significantly correlated with the position of the terminator on the lunar surface.

Srnka, L. J.

1977-01-01

144

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) College of Staten Island, City University of New York, USA (3) Inst. Surface Chemistry and Catalysis, Ulm

Pfeifer, Holger

145

Demonstrations with a Vacuum: Old Demonstrations for New Vacuum Pumps.  

ERIC Educational Resources Information Center

Explains mechanisms of 19th-century vacuum pumps. Describes demonstrations using the pump including guinea and feather tube, aurora tube, electric egg, Gassiots cascade, air mill, bell in vacuum, density and buoyancy of air, fountain in vacuum, mercury shower, palm and bladder glasses, Bacchus demonstration, pneumatic man-lifter, and Magdeburg…

Greenslade, Thomas B., Jr.

1989-01-01

146

Jump phenomena of current in PZT-vibrators due to nonlinear damping of surrounding media  

Microsoft Academic Search

In some applications, surrounding media influence oscillating behavior of PZT vibrators by non-linear damping. This usually results in current jump phenomena of the supply. Such effects have been studied in detail under both atmospheric air pressure and vacuum. For a rate estimation about the influence of nonlinear crystal properties and of nonlinear damping the media influence has been minimized by

P Drögmöller; G Gerlach

2001-01-01

147

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

NASA Astrophysics Data System (ADS)

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 °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 °C. The wear rate of the films decreased sharply when annealed at 200 or 300 °C. Structural analysis shows that annealing at 300 °C improved tribological properties originated from the volume increase in the fullerenelike microstructure, and further annealing at 600 °C improved mechanical properties originated from the transformation of nanosized curved sp2 to sp3 clusters.

Wang, Qi; He, Deyan; Wang, Chengbing; Wang, Zhou; Zhang, Junyan

2008-08-01

148

Explanation of Superluminal Phenomena Based on Particle-Wave Duality and Proposed Optical Experiments  

E-print Network

We suggest an explanation for superluminal phenomena based on wave-particle duality of photons. Individual photon can be regarded as a wavepacket, whose spatial extension is its coherence volume. As a photon propagates as a wave train, its velocity cannot exceed the speed of light in vacuum. When it tunnels through a barrier as a particle, its wave function collapses and it travels faster than light. But superluminal phenomena can occur only within the coherence length, and the duration is restricted by the uncertainty principle. On the other hand, a particle with non-vanishing mass cannot travel faster than light. So superluminal phenomena do not violate causality. We explain the principle of existing superluminal experiments and proposed three types of experiments to further verify superluminal phenomena. The first is to show that a single photon is equivalent to a wavepacket, which occupies certain spatial volume. The second demonstrates that superluminal phenomena can occur only within the coherence lengt...

Zhao, Hai-Long

2014-01-01

149

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

150

Critical phenomena in complex networks  

E-print Network

The combination of the compactness of networks, featuring small diameters, and their complex architectures results in a variety of critical effects dramatically different from those in cooperative systems on lattices. In the last few years, researchers have made important steps toward understanding the qualitatively new critical phenomena in complex networks. We review the results, concepts, and methods of this rapidly developing field. Here we mostly consider two closely related classes of these critical phenomena, namely structural phase transitions in the network architectures and transitions in cooperative models on networks as substrates. We also discuss systems where a network and interacting agents on it influence each other. We overview a wide range of critical phenomena in equilibrium and growing networks including the birth of the giant connected component, percolation, k-core percolation, phenomena near epidemic thresholds, condensation transitions, critical phenomena in spin models placed on networks, synchronization, and self-organized criticality effects in interacting systems on networks. We also discuss strong finite size effects in these systems and highlight open problems and perspectives.

S. N. Dorogovtsev; A. V. Goltsev; J. F. F. Mendes

2007-04-30

151

Tritium handling in vacuum systems  

SciTech Connect

This report provides a course in Tritium handling in vacuum systems. Topics presented are: Properties of Tritium; Tritium compatibility of materials; Tritium-compatible vacuum equipment; and Tritium waste treatment.

Gill, J.T. [Monsanto Research Corp., Miamisburg, OH (United States). Mound Facility; Coffin, D.O. [Los Alamos National Lab., NM (United States)

1986-10-01

152

Vacuum Energy in Quantum Graphs  

E-print Network

We calculate the vacuum energy in quantum graphs. Vacuum energy arose in quantum physics but has an independent mathematical interest as a functional carrying information about the eigenvalue spectrum of a system. A quantum graph is a metric graph...

Wilson, Justin

2007-07-14

153

Pulsed laser ablation of solids and critical phenomena  

NASA Astrophysics Data System (ADS)

We consider the possible manifestations of critical phenomena under pulsed laser ablation (PLA). The mechanism of phase explosion under nanosecond laser ablation is considered and the possibility of estimating the critical temperature from PLA experiments is discussed. A model based on the Euler equations and generalized van der Waals equation is developed to describe rarefaction shock waves (RSW) in near-critical matter. For a near-surface slab of a gold target heated above the critical point and expanding freely in vacuum, the evolution of the RSW has been studied. The possibility of RSW formation in stellar matter is discussed.

Bulgakova, Nadezhda M.; Bulgakov, Alexander V.; Bourakov, Igor M.; Bulgakova, Natalia A.

2002-09-01

154

Vacuum Frying of Carrot Chips  

Microsoft Academic Search

Vacuum frying is an alternative method to produce high quality vegetable or fruit chips. The effect of frying temperature and vacuum degree on moisture content, oil content, color, and texture of fried carrot chips were investigated. During the early stage of vacuum frying, the rate of moisture removal and oil absorption increased with increasing frying oil temperature and degree of

Liu-ping Fan; Min Zhang; Arun S. Mujumdar

2005-01-01

155

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

156

Vacuum Energy: Myths and Reality  

E-print Network

We discuss the main myths related to the vacuum energy and cosmological constant, such as: ``unbearable lightness of space-time''; the dominating contribution of zero point energy of quantum fields to the vacuum energy; non-zero vacuum energy of the false vacuum; dependence of the vacuum energy on the overall shift of energy; the absolute value of energy only has significance for gravity; the vacuum energy depends on the vacuum content; cosmological constant changes after the phase transition; zero-point energy of the vacuum between the plates in Casimir effect must gravitate, that is why the zero-point energy in the vacuum outside the plates must also gravitate; etc. All these and some other conjectures appear to be wrong when one considers the thermodynamics of the ground state of the quantum many-body system, which mimics macroscopic thermodynamics of quantum vacuum. In particular, in spite of the ultraviolet divergence of the zero-point energy, the natural value of the vacuum energy is comparable with the observed dark energy. That is why the vacuum energy is the plausible candidate for the dark energy.

G. E. Volovik

2006-04-14

157

Transport Phenomena and Materials Processing  

NASA Astrophysics Data System (ADS)

An extremely useful guide to the theory and applications of transport phenomena in materials processing This book defines the unique role that transport phenomena play in materials processing and offers a graphic, comprehensive treatment unlike any other book on the subject. The two parts of the text are, in fact, two useful books. Part I is a very readable introduction to fluid flow, heat transfer, and mass transfer for materials engineers and anyone not yet thoroughly familiar with the subject. It includes governing equations and boundary conditions particularly useful for studying materials processing. For mechanical and chemical engineers, and anyone already familiar with transport phenomena, Part II covers the many specific applications to materials processing, including a brief description of various materials processing technologies. Readable and unencumbered by mathematical manipulations (most of which are allocated to the appendixes), this book is also a useful text for upper-level undergraduate and graduate-level courses in materials, mechanical, and chemical engineering. It includes hundreds of photographs of materials processing in action, single and composite figures of computer simulation, handy charts for problem solving, and more. Transport Phenomena and Materials Processing: * Describes eight key materials processing technologies, including crystal growth, casting, welding, powder and fiber processing, bulk and surface heat treating, and semiconductor device fabrication * Covers the latest advances in the field, including recent results of computer simulation and flow visualization * Presents special boundary conditions for transport phenomena in materials processing * Includes charts that summarize commonly encountered boundary conditions and step-by-step procedures for problem solving * Offers a unique derivation of governing equations that leads to both overall and differential balance equations * Provides a list of publicly available computer programs and publications relevant to transport phenomena in materials processing

Kou, Sindo

1996-10-01

158

Amorphous-crystalline transformation and conductivity enhancement in annealed bismuth sulphide thin films  

Microsoft Academic Search

Post-deposition vacuum annealing of chemically deposited Bi2S3 thin films has been found to enhance the dark conductivity of the films from approximately=10-7 Omega cm-1 to approximately=102 Omega -1 cm-1 and the photoconductivity from approximately 10-5 Omega cm-1 to approximately=102 Omega cm-1. Such increase is attributed to (i) an amorphous-to-crystalline transformation of the setting in at approximately=175 degrees C, confirmed by

P. K. Nair; J. Campos; A. Sanchez; L. Banos; M. T. S. Nair

1991-01-01

159

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

Microsoft Academic Search

In this work, we discuss fabrication and characterization of MgB2 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 MgB2 thin films showed superconducting critical transition at 33K after annealing at 650°C.

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

2007-01-01

160

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

161

Discovery Potential for New Phenomena  

E-print Network

We examine the ability of future facilities to discover and interpret non-supersymmetric new phenomena. We first explore explicit manifestations of new physics, including extended gauge sectors, leptoquarks, exotic fermions, and technicolor models. We then take a more general approach where new physics only reveals itself through the existence of effective interactions at lower energy scales. [Summary Report of the New Phenomena Working Group. To appear in the Proceedings of the 1996 DPF/DPB Summer Study on New Directions for High Energy Physics - Snowmass96, Snowmass, CO, 25 June - 12 July 1996.

Stephen Godfrey; JoAnne L. Hewett; Lawrence E. Price

1997-04-10

162

Can the Vacuum Be Engineered for Space¯ight Applications?  

Microsoft Academic Search

Abstract ? Quantum theory predicts, and experiments verify, that empty space,(the vacuum),contains,an enormous,residual background,energy known,as zero-point energy (ZPE). Originally thought to be of significance only for such esoteric concerns,as small perturbations,to atomic,emission processes, it is now known to play a role in large-scale phenomena of interest to technologists as well, such as the inhibition of spontaneous emission, the generation of

H. E. Puthoff

163

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

164

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

165

Vacuum Structure and Potential  

E-print Network

Based on overall experimental observations, especially the pair processes, I developed a model structure of the vacuum along with a basic-particle formation scheme begun in 2000 (with collaborator P-I Johansson). The model consists in that the vacuum is, briefly, filled of neutral but polarizable vacuuons, consisting each of a p-vaculeon and n- vaculeon of charges $+e$ and $-e$ of zero rest masses but with spin motions, assumed interacting each other with a Coulomb force. The model has been introduced in full in a book (Nova Sci, 2005) and referred to in a number of journal/E-print papers. I outline in this easier accessible paper the detailed derivation of the model and a corresponding quantitative determination of the vacuuon size.

J. X. Zheng-Johansson

2007-04-02

166

An automated vacuum system  

SciTech Connect

Software tools available with the Ground Test Accelerator (GTA) control system provide the capability to express a control problem as a finite state machine. System states and transitions are expressed in terms of accelerator parameters and actions are taken based on state transitions. This is particularly useful for sequencing operations which are modal in nature or are unwieldy when implemented with conventional programming. State diagrams are automatically translated into code which is executed by the control system. These tools have been applied to the vacuum system for the GTA accelerator to implement automatic sequencing of operations. With a single request, the operator may initiate a complete pump-down sequence. He can monitor the progress and is notified if an anomaly occurs requiring intervention. The operator is not required to have detailed knowledge of the vacuum system and is protected from taking inappropriate actions. 1 ref., 6 figs.

Atkins, W.H. (Oak Ridge National Lab., TN (USA)); Vaughn, G.D. (Los Alamos National Lab., NM (USA)); Bridgman, C. (Grumman Corp., Bethpage, NY (USA))

1991-01-01

167

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

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

Note: development of fast heating inert gas annealing apparatus operated at atmospheric pressure.  

PubMed

Here, we report the development of a simple, small, fast heating, and portable, homemade, inert gas (Ar) atmospheric annealing setup. Instead of using a conventional heating element, a commercial soldering rod having an encapsulated fast heating heater is used here. The sample holder is made of a block of stainless steel. It takes 200 s to reach 700 °C, and 10 min to cool down. The probability of oxidation or surface contamination has been examined by means of x ray photoelectron spectroscopy of virgin Cu sample after annealing at 600 °C. In addition, we compare the annealing of a hydrogenated carbon nitride film (HCN(x)) in both a conventional vacuum and our newly developed ambient Ar atmosphere setup. PMID:22559595

Das, S C; Majumdar, A; Shripathi, T; Hippler, R

2012-04-01

170

Effects of annealing on the ripple texture and mechanical properties of suspended bilayer graphene  

NASA Astrophysics Data System (ADS)

Periodic ripples of amplitude ˜15 nm were formed in suspended bilayer graphene after nanoindentation with incremental forces up to 600 nN. The structure was annealed at ˜620 K in high vacuum and the corresponding modifications in the mechanical properties and surface morphology were investigated. The pre-tension of the pristine sample was found to be 1.46 N m-1 and after annealing it was reduced to 0.72 N m-1. The nanometre-sized ripples induced by mechanical excitation were found to be flattened after annealing. Tailoring surface corrugations in bilayer graphene through nanoindentation and thermal engineering of these ripples thus provides an innovative fabrication route for flexible electronic devices and strain sensors.

Annamalai, M.; Mathew, S.; Jamali, M.; Zhan, D.; Palaniapan, M.

2013-04-01

171

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

172

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

173

Flow phenomena in rocks: from continuum models to fractals, percolation, cellular automata, and simulated annealing  

Microsoft Academic Search

In this paper, theoretical and experimental approaches to flow, hydrodynamic dispersion, and miscible and immiscible displacement processes in reservoir rocks are reviewed and discussed. Both macroscopically homogeneous and heterogeneous rocks are considered. The latter are characterized by large-scale spatial variations and correlations in their effective properties and include rocks that may be characterized by several distinct degrees of porosity, a

Muhammad Sahimi

1993-01-01

174

Theory of dynamic critical phenomena  

Microsoft Academic Search

An introductory review of the central ideas in the modern theory of dynamic critical phenomena is followed by a more detailed account of recent developments in the field. The concepts of the conventional theory, mode-coupling, scaling, universality, and the renormalization group are introduced and are illustrated in the context of a simple example-the phase separation of a symmetric binary fluid.

P. C. Hohenberg; B. I. Halperin

1977-01-01

175

Critical phenomena in atmospheric precipitation  

E-print Network

LETTERS Critical phenomena in atmospheric precipitation OLE PETERS1,2,3 * AND J. DAVID NEELIN3 1 critical value, an order parameter increases as a power law. At criticality, order-parameter fluctuations and order parameter are coupled, the critical point can become an attractor, and self-organized criticality

Loss, Daniel

176

Discovery potential for new phenomena  

SciTech Connect

The authors examine the ability of future facilities to discover and interpret non-supersymmetric new phenomena. The authors first explore explicit manifestations of new physics, including extended gauge sectors, leptoquarks, exotic fermions, and technicolor models. They then take a more general approach where new physics only reveals itself through the existence of effective interactions at lower energy scales.

Godfrey, S. [Carleton Univ., Ottawa, Ontario (Canada). Ottawa Carleton Inst. for Physics; Hewett, J.L. [Stanford Linear Accelerator Center, Menlo Park, CA (United States); Price, L.E. [Argonne National Lab., IL (United States). High Energy Physics Div.

1997-03-01

177

Burst phenomena in solar flares  

Microsoft Academic Search

Solar flares are rapid dissipative processes in which the energy accumulated in the magnetic field is released in the forms of plasma heating, explosive plasma flows with flare shock generations, particle accelerations, and emissions in a very broad range of frequencies ranging from radio waves up to gamma-rays. As solar flares and related phenomena influence not only the processes in

P. Kotrc; Yu. A. Kupryakov; J. Jurcák

2002-01-01

178

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

179

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

180

Affective phenomena - descriptive and theoretical  

Microsoft Academic Search

Reviews the work of 15 researchers (1910-1911), in the field of affective phenomena. The topics covered include a critical review of work in the field of affective psychology in the past 10 years, the theory of pleasure, the theory of empirical \\

H. N. Gardiner

1911-01-01

181

Transport phenomena in material processing  

Microsoft Academic Search

Research activity related to material processing and manufacturing has been substantially increased in recent years. This increase is largely motivated by the growing sophistication in the nature of modern processes and the continuing quest for better productivity and less cost in the industry. Researchers in the heat transfer community have contributed significantly to gaining fundamental understanding of the transport phenomena

M. Charmichi; M. K. Chyu; Y. Joshi; S. M. Walsh

1990-01-01

182

Nuclear pairing: basic phenomena revisited  

E-print Network

I review the phenomena associated with pairing in nuclear physics, most prominently the ubiquitous presence of odd-even mass differences and the properties of the excitation spectra, very different for even-even and odd-A nuclei. There are also significant dynamical effects of pairing, visible in the inertias associated with nuclear rotation and large-amplitude shape deformation.

G. F. Bertsch

2012-03-25

183

Vacuum Energy: Myths and Reality  

E-print Network

We discuss the main myths related to the vacuum energy and cosmological constant, such as: ``unbearable lightness of space-time''; the dominating contribution of zero point energy of quantum fields to the vacuum energy; non-zero vacuum energy of the false vacuum; dependence of the vacuum energy on the overall shift of energy; the absolute value of energy only has significance for gravity; the vacuum energy depends on the vacuum content; cosmological constant changes after the phase transition; zero-point energy of the vacuum between the plates in Casimir effect must gravitate, that is why the zero-point energy in the vacuum outside the plates must also gravitate; etc. All these and some other conjectures appear to be wrong when one considers the thermodynamics of the ground state of the quantum many-body system, which mimics macroscopic thermodynamics of quantum vacuum. In particular, in spite of the ultraviolet divergence of the zero-point energy, the natural value of the vacuum energy is comparable with the...

Volovik, G E

2006-01-01

184

Electromagnetic imaging and simulated annealing  

NASA Astrophysics Data System (ADS)

In contrast with acoustical imaging methods, for which the wave field is dominated by propagation effects, electromagnetic imaging of conductive media suffers from the diffusive behavior of the electromagnetic field. An important question to address when working toward the achievement of electromagnetic imaging concerns the possibility of resolving the diffusion damping. Exact inversion will be looking at the solvability of the integral equation relating a diffusive field to its dual wavefield. This equation is ill posed because its Laplace-like kernel makes the inverse problem of finding the dual wave field a notoriously difficult (both numerically and mathematically) one. Stochastic inversion is another alternative based on least squares fitting. In this inverse problem approach, extracting the wave field is still a relatively instable process, although the L2 misfit function for data without noise presents a global minimum. The simulated annealing overcomes this instability for parameterization of this problem designed as follows. The unknown wave field is expected to be a sequence of impulsive functions. The number of impulsive functions can be determined by using a statistical criterion, called AIC, which comes from the Prony technique. The simulated annealing is applied to the positions of the reflections, while the amplitudes, which are not taken as parameters, are obtained by linear fitting. The simulated annealing method proves to be efficient even in the presence of noise. Furthermore, this nonlinear numerical inversion furnishes statistical quantities which allows an estimation of the resolution. Simple synthetic examples illustrate the performance of the inversion, while a synthetic finite element example shows the final pseudo-seismic section to be processed by standard seismic migration techniques.

Gibert, Dominique; Virieux, Jean

1991-05-01

185

Relationship between Yield Point Phenomena and the Nanoindentation Pop-in Behavior of Steel  

SciTech Connect

Pop-ins on nanoindentation load-displacement curves of a ferritic steel were correlated with yield drops on its tensile stress-strain curves. To investigate the relationship between these two phenomena, nanoindentation and tensile tests were performed on annealed specimens, prestrained specimens, and specimens aged for various times after prestraining. Clear nanoindentation pop-ins were observed on annealed specimens, which disappeared when specimens were indented right after the prestrain, but reappeared to varying degrees after strain aging. Yield drops in tensile tests showed similar disappearance and appearance, indicating that the two phenomena, at the nano- and macro-scale, respectively, are closely related and influenced by dislocation locking by solutes (Cottrell atmospheres).

Ahn, T.-H. [Seoul National University; Oh, C.-S. [Korean Institute of Materials Science; Lee, K. [Technical Research Laboratories, Republic of Korea; George, Easo P [ORNL; Han, H. N. [Seoul National University

2012-01-01

186

Fatigue crack propagation in type 316 stainless steel in vacuum and air environments  

NASA Astrophysics Data System (ADS)

The fatigue crack propagation performance of unirradiated type 316 stainless steel was investigated in vacuum for comparison with results in an air environment under continuous cycling and hold time conditions. The materials included both fast breeder reactor (FBR) and magnetic fusion energy (MFE) reference type 316 steels. The continuous cycling results showed that the crack propagation rates of annealed FBR and MFE materials were essentially identical in a vacuum of 6.7 × 10 -6 Pa at 550° C. However, a significant reduction in crack propagation rates was observed for the FBR material in vacuum at 593°C when compared with the results in the air environment at 593°C. For 20 percent cold worked steel, the results showed that the crack propagation rates for the MFE material at 550°C in vacuum were lower than for the annealed MFE material at this temperature. These results were consistent with data for 20 percent cold worked FBR material at 593° C which showed that cold work reduced the rates of fatigue crack propagation when compared with annealed material. Hold time effects for both steels were significantly larger for evaluations conducted in vacuum or in air after irradiation as compared with previous unirradiated air results. Scanning electron microscope examination of the specimens tested in vacuum showed that the mode of crack propagation was entirely ductile and transgranular in character for continuous cycling tests and typically intergranular for hold time evaluations. The vacuum results obtained in this study were compared with the data for type 316 stainless steel tested in air for both the irradiated and the unirradiated conditions. The relationships developed from these comparisons suggest that the existing data will be of value to fusion design when consideration is given to the effects of environment and irradiation.

Michel, D. J.; Smith, H. H.

187

The effect of annealing ambient on the characteristics of an indium-gallium-zinc oxide thin film transistor.  

PubMed

In this study, the effects of different annealing conditions (air, O2, N2, vacuum) on the chemical and electrical characteristics of amorphous indium-gallium-zinc oxide (a-IGZO) thin film transistors (TFT) were investigated. The contact resistance and interface properties between the IGZO film and the gate dielectric improved after an annealing treatment. However, the chemical bonds in the IGZO bulk changed under various annealing atmospheres, which, in turn, altered the characteristics of the TFTs. The TFTs annealed in vacuum and N2 ambients exhibited undesired switching properties due to the high carrier concentration (>10(17) cm(-3)) of the IGZO active layer. In contrast, the IGZO TFTs annealed in air and oxygen ambients displayed clear transfer characteristics due to an adequately adjusted carrier concentration in the operating range of the TFT. Such an optimal carrier concentration arose through the stabilization of unstable chemical bonds in the IGZO film. With regard to device performance, the TFTs annealed in O2 and air exhibited saturation mobility values of 8.29 and 7.54 cm2/Vs, on-off ratios of 7.34 x 10(8) and 3.95 x 10(8), and subthreshold swing (SS) values of 0.23 and 0.19 V/decade, respectively. Therefore, proper annealing ambients contributed to internal modifications in the IGZO structure and led to an enhancement in the oxidation state of the metal. As a result, defects such as oxygen vacancies were eliminated. Oxygen annealing is thus effective for controlling the carrier concentration of the active layer, decreasing electron traps, and enhancing TFT performance. PMID:22121652

Park, Soyeon; Bang, Seokhwan; Lee, Seungjun; Park, Joohyun; Ko, Youngbin; Jeon, Hyeongtag

2011-07-01

188

Charged vacuum bubble stability  

NASA Astrophysics Data System (ADS)

A type of scenario is considered where electrically charged vacuum bubbles, formed from degenerate or nearly degenerate vacua separated by a thin domain wall, are cosmologically produced due to the breaking of a discrete symmetry, with the bubble charge arising from fermions residing within the domain wall. Stability issues associated with wall tension, fermion gas, and Coulombic effects for such configurations are examined. The stability of a bubble depends upon parameters such as the symmetry breaking scale and the fermion coupling. A dominance of either the Fermi gas or the Coulomb contribution may be realized under certain conditions, depending upon parameter values.

Morris, J. R.

1999-01-01

189

Annealing of aromatic polyimide precursors  

NASA Technical Reports Server (NTRS)

A study has been made of the thermal behavior of polyimide precursors: an isomeric pair of crystals of the complex formed by p-phenylenediamine with the separated isomers of the di-isopropyl ester of pyromellitic acid. Specimens of this material were isothermally annealed in the temperature range 120 C to 170 C for periods of time up to 1 week. Although this temperature range is well below that customarily used for imidizations, the working hypothesis was that it would be more likely that a polymer embodying at least part of the precursor structure could be formed if the molecular motion was minimized to that actually required for the formation of the imide linkage. The progress of the annealing was followed by: infrared spectroscopy, differential thermal analysis, powder X-ray diffraction, and thermal gravimetric analysis. Single crystal X-ray analysis of the meta monomer yields a structure of chains of alternating acid and base and suggests that this monomer is amenable to polymerization with a minimum of geometrical disruption.

Wakelyn, N. T.

1975-01-01

190

thin films by thermal annealing  

NASA Astrophysics Data System (ADS)

La2/3Ba1/3MnO3:Ag0.04 (LBMO:Ag0.04) thin films were prepared on single crystalline (001)-orientated LaAlO3 substrates by pulsed laser deposition technique. Thermal annealing with temperatures of 780, 800 and 820 °C has been investigated to improve electrical properties of the films. All the samples are shown along the (00 l) orientation in rhombohedral structure with space group. With thermal annealing temperature increasing, insulator-metal transition temperature ( T p) and resistivity at T p () of the epilayer reach optimal value of 288 K and 0.03 ?·cm, respectively. The electrical properties improvement of the LBMO:Ag0.04 films is due to an improved film crystallization, oxygen balance and photon scattering suppression. The fitting curves show that the region of ferro-magnetic metallic (FM, T < T p) is fitted with grain/domain boundary, electron-electron and magnon scattering mechanism, as well as the region of para-magnetic insulating (PI, T > T p) is fitted with adiabatic small polaron hopping mechanism.

Liu, Xiang; Yin, Xue-Peng; Chen, Qing-Ming; Zhang, Hui; Zhang, Shao-Chun

2014-09-01

191

Accretion Disks and Eruptive Phenomena  

E-print Network

This paper describes eruptive phenomena in pre-main sequence stars. The eruptions of FU Orionis stars have much in common with outbursts in other accreting systems, such as dwarf novae and some symbiotic stars. These common features are best understood as increases in the rate material flows through an accretion disk. The spectroscopic properties, decay of the light curves, and outflow phenomena suggest that these outbursts arise from thermal instabilities in the disk. Available data and estimates for recurrence times indicate that young stars can accrete much, perhaps all, of their mass in FU Ori accretion events. Future observations can test this notion and place better constraints on the importance of eruptive events in the early life of a low mass star.

Scott J. Kenyon

1999-04-02

192

Statistical phenomena in particle beams  

SciTech Connect

Particle beams are subject to a variety of apparently distinct statistical phenomena such as intrabeam scattering, stochastic cooling, electron cooling, coherent instabilities, and radiofrequency noise diffusion. In fact, both the physics and mathematical description of these mechanisms are quite similar, with the notion of correlation as a powerful unifying principle. In this presentation we will attempt to provide both a physical and a mathematical basis for understanding the wide range of statistical phenomena that have been discussed. In the course of this study the tools of the trade will be introduced, e.g., the Vlasov and Fokker-Planck equations, noise theory, correlation functions, and beam transfer functions. Although a major concern will be to provide equations for analyzing machine design, the primary goal is to introduce a basic set of physical concepts having a very broad range of applicability.

Bisognano, J.J.

1984-09-01

193

Dynamic critical phenomena in fractals  

NASA Astrophysics Data System (ADS)

Dynamic critical phenomena are investigated, via the spin-flip kinetic Ising model, on two finitely ramified fractals: the Sierpinski gasket (SG) and the Koch curve. We show, using the Kawasaki inequality, that the dynamic critical exponent of the SG satisfies z>=df, the lower bound forming the conventional value. We also formulate a lower bound for the characteristic decay time. For the Koch curve we show exactly that z=2df=dw, where dw is the random-walk dimension.

Luscombe, James H.; Desai, Rashmi C.

1985-07-01

194

Coherent phenomena in photonic crystals  

Microsoft Academic Search

We study the spontaneous emission, the absorption and dispersion properties\\u000aof a ${\\\\bf \\\\Lambda}$-type atom where one transition interacts near resonantly\\u000awith a double-band photonic crystal. Assuming an isotropic dispersion relation\\u000anear the band edges, we show that two distinct coherent phenomena can occur.\\u000aFirst, the spontaneous emission spectrum of the adjacent free space transition\\u000aobtains `dark lines' (zeroes in

D. G. Angelakis; E. Paspalakis; P. L. Knight

2001-01-01

195

Coherent phenomena in photonic crystals  

Microsoft Academic Search

We study the spontaneous emission, absorption, and dispersion properties of a Lambda-type atom where one transition interacts near resonantly with a double-band photonic crystal. Assuming an isotropic dispersion relation near the band edges, we show that two distinct coherent phenomena can occur. First the spontaneous emission spectrum of the adjacent free-space transition obtains ``dark lines'' (zeros in the spectrum). Second,

D. G. Angelakis; E. Paspalakis; P. L. Knight

2001-01-01

196

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

197

Functional imaging of mucociliary phenomena  

Microsoft Academic Search

We present a technique for the investigation of mucociliary phenomena on trachea explants under conditions resembling those\\u000a in the respiratory tract. Using an enhanced reflection contrast, we detect simultaneously the wave-like modulation of the\\u000a mucus surface by the underlying ciliary activity and the transport of particles embedded in the mucus layer. Digital recordings\\u000a taken at a speed of 500 frames

M. Ryser; A. Burn; Th. Wessel; M. Frenz; J. Ri?ka

2007-01-01

198

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

199

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

200

The oxidization behavior and mechanical properties of ultrananocrystalline diamond films at high temperature annealing  

NASA Astrophysics Data System (ADS)

Ultrananocrystalline diamond (UNCD) films prepared by hot filament chemical vapor deposition (HFCVD) were annealed at 1000 °C in low degree vacuum under a pressure of 4000 Pa. The correlation between the mechanical and structural properties was investigated to understand the oxidization behavior of UNCD films after high temperature annealing. At the early stage of annealing (?30 min), the amorphous carbon and graphite in grain boundaries are selectively oxidized firstly along the clusters’ gaps, with the Young's modulus and hardness decreasing rapidly revealed by nanoindentation results. A special annealing time of ?30-60 min is found to exist as a turning point that the mechanical properties changing trend has a transition, because of the diamond grains starting to be oxidized. With the annealing time increasing to 180 min, the nanoindentation depth increases from ?70 to ?90 nm and the Young's modulus and hardness decrease more slowly with almost keeping constant of ?383 and ?35 GPa, respectively. X-ray photoelectron spectroscopy (XPS) results show that a steady 30-nm-thick oxidized layer has been formed on the top-surface and keeps a balance of the speed between films being oxidized and the carbon oxidation being broken down.

Huang, Kai; Hu, Xiaojun; Xu, Hui; Shen, Yaogen; Khomich, Alex

2014-10-01

201

Vacuum vapor deposition  

NASA Technical Reports Server (NTRS)

A method and apparatus is described for vapor deposition of a thin metallic film utilizing an ionized gas arc directed onto a source material spaced from a substrate to be coated in a substantial vacuum while providing a pressure differential between the source and the substrate so that, as a portion of the source is vaporized, the vapors are carried to the substrate. The apparatus includes a modified tungsten arc welding torch having a hollow electrode through which a gas, preferably inert, flows and an arc is struck between the electrode and the source. The torch, source, and substrate are confined within a chamber within which a vacuum is drawn. When the arc is struck, a portion of the source is vaporized and the vapors flow rapidly toward the substrate. A reflecting shield is positioned about the torch above the electrode and the source to ensure that the arc is struck between the electrode and the source at startup. The electrode and the source may be confined within a vapor guide housing having a duct opening toward the substrate for directing the vapors onto the substrate.

Poorman, Richard M. (inventor); Weeks, Jack L. (inventor)

1995-01-01

202

Accelerator Vacuum Protection System  

NASA Astrophysics Data System (ADS)

A new and elaborate automatic vacuum protection system using fast acting valve has been installed to avoid accidental venting of accelerator from experimental chamber side. To cover all the beam lines and to reduce the system cost, it has been installed at a common point from where all the seven beam lines originate. The signals are obtained by placing fast response pressure sensing gauges (HV SENSOR) near all the experimental stations. The closing time of the fast valve is 10 milli-second. The fast closing system protects only one vacuum line at a time. At IUAC, we have seven beam lines so one sensor was placed in each of the beam lines near experimental chamber and a multiplexer was incorporated into the fast closing system. At the time of experiment, the sensor of the active beam line is selected through the multiplexer and the Fast closing valve is interlocked with the selected sensor. As soon as the pressure sensor senses the pressure rise beyond a selected pressure, the signal is transferred and the fast valve closes within 10 to 12 millisecond.

Barua, Pradip; Kothari, Ashok; Archunan, M.; Joshi, Rajan

2012-11-01

203

Electrical annealing for flexible organic light-emitting diodes having poly(3,4-ethylenedioxythiophene):poly(styrene sulfonate) anodes  

NASA Astrophysics Data System (ADS)

We present a postproduction method of electrical annealing (E-annealing) to improve the performance of flexible organic light-emitting diodes (FOLEDs) having conductive polymer anodes on a polyethersulfone substrate. The polymer that was used for the anodes was dimethylsulfoxide-doped poly(3,4-ethylenedioxythiophene):poly(styrene sulfonate). It was found that E-annealing of the fabricated FOLEDs can reduce the turn-on voltage and enhance the brightness with reduced flowing current, thereby enhancing the device efficiency. With the E-annealing method, we have successfully demonstrated efficient solution-processed green FOLEDs, which show a peak luminescence of 6 100 cd/m2 and a maximum current efficiency of 16.4 cd/A. An ion migration model to explain the phenomena related to the improvement of FOLEDs is also proposed.

Park, Byoungchoo; Park, Chan Hyuk; Yim, Younchan; Park, Jongwoon

2010-10-01

204

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

205

HIV-1 primer annealing The annealing mechanism of HIV-1 reverse transcription primer onto the  

E-print Network

HIV-1 primer annealing 1 The annealing mechanism of HIV-1 reverse transcription primer onto CNRS, Faculté de Pharmacie, 4 avenue de l'Observatoire, 75006 PARIS. Running title : HIV-1 primer 99 93 Fax : +33 1 53 73 99 25 #12;HIV-1 primer annealing 2 SUMMARY Reverse transcription of HIV-1

Paris-Sud XI, Université de

206

Vacuum leak detector and method  

DOEpatents

Apparatus and method for detecting leakage in a vacuum system involves a moisture trap chamber connected to the vacuum system and to a pressure gauge. Moisture in the trap chamber is captured by freezing or by a moisture adsorbent to reduce the residual water vapor pressure therein to a negligible amount. The pressure gauge is then read to determine whether the vacuum system is leaky. By directing a stream of carbon dioxide or helium at potentially leaky parts of the vacuum system, the apparatus can be used with supplemental means to locate leaks.

Edwards, Jr., David (7 Brown's La., Bellport, NY 11713)

1983-01-01

207

Manipulator For A Vacuum Chamber  

NASA Technical Reports Server (NTRS)

Rotary seal provides for external actuators. Positioner in vacuum employs four actuators; up/down, horizontal rotary, horizontal, and vertical rotary. External up/down and azimuthal actuators drives shaft entering vacuum chamber through sliding and rotating seal. Placement of actuator motors outside vacuum chamber reduces heat-removal load on system. Atop 2.5-cm-diameter shaft is stage supporting masses as great as 15 kg. Small motors on stage provide horizontal translation and rotation in vertical plane. Manipulator developed for calibrating plasma detectors by subjecting them to particle beams in vacuum. Standard, commercially available parts used.

Hunsaker, F.; Ogilvie, K.

1988-01-01

208

Investigation of the room temperature annealing peak in ionomers  

SciTech Connect

A number of studies appearing in the literature have documented an endothermic peak in differential scanning calorimetry (DSC) scans for ethylene-methacrylic acid copolymer ionomers which appears only upon annealing at room temperature. This peak has been attributed to either polyethylene crystallites, ionic crystallite, or water absorption. In a novel polyurethane cationomer with a quarternized amine contained in hard segment, the same phenomena has been found in DSC scans when the neutralizing anion is bromine or iodine. Since this material does not crystallize, the authors were able to conclusively eliminate crystallization as the cause of the endotherm. The extended x-ray absorption fine structure (EXAFS) of bromine has been measured to differentiate between water absorption and ionic crystallites. Spectra were collected above and below the temperature corresponding to the endothermic peak. The results of the EXAFS analysis will be presented.

Goddard, R.J.; Grady, B.P.; Cooper, S.L. [Univ. of Wisconsin-Madison, WI (United States)

1993-12-31

209

Desorption of InSb(001) native oxide and surface smoothing induced by low temperature annealing under molecular hydrogen flow  

NASA Astrophysics Data System (ADS)

The preparation of InSb (001) oxygen-free surfaces by thermal annealing at relatively low temperatures under molecular hydrogen flow is reported. This process is compared with thermal oxide desorption (TOD) at 400°C under ultrahigh vacuum conditions. Molecular hydrogen cleaning (MHC) at substrate temperature of 250°C and at hydrogen pressure of 5×10-6Torr resulted in complete desorption of the native oxide layer. Furthermore, no carbon contamination was observed on the surface following this treatment. The surface morphology of the samples following this process was found to be very smooth without any droplet structure. The In:Sb surface stoichiometry was nearly 1:1 along the MHC process. In addition, annealing the sample at 400°C in vacuum after oxide removal by MHC maintains the smoothness and the stoichiometry of the surface. In contrast, TOD at 400°C of an oxidized InSb surface in vacuum does not result in complete oxide removal from the surface. Furthermore, small droplets associated with In are produced at this annealing temperature. The surface stoichiometry shows In enrichment after TOD in vacuum above 360°C. The surface composition and chemical bonding were monitored by Auger electron spectroscopy and x-ray photoelectron spectroscopy as a function of process parameters. The surface morphology was analyzed by atomic force microscopy.

Tessler, R.; Saguy, C.; Klin, O.; Greenberg, S.; Weiss, E.; Akhvlediani, R.; Edrei, R.; Hoffman, A.

2007-01-01

210

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

211

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

212

Discrete Optimization A simulated annealing approach  

E-print Network

is NP-complete since it is a generalization of the rectangular cutting stock problem, which in turnDiscrete Optimization A simulated annealing approach for the circular cutting problem Mhand Hifi for the constrained and the unconstrained circular cutting problem based upon simulated annealing. We define an energy

Zissimopoulos, Vassilis

213

Discrete Optimization A simulated annealing approach  

E-print Network

problem is NP­complete since it is a generalization of the rectangular cutting stock problem, whichDiscrete Optimization A simulated annealing approach for the circular cutting problem Mhand Hifi for the constrained and the unconstrained circular cutting problem based upon simulated annealing. We define an energy

Zissimopoulos, Vassilis

214

Cosmic Vacuum Prevents Radiopanspermia  

NASA Astrophysics Data System (ADS)

The paper describes the new physical mechanism for the explanation of the irreversible damage of vegetative cells and spores of microorganisms (m/o) under space thermovacuum conditions (tvc) (vacuum+high temperatures), developed by the authors based on the published experimental data of various authors. The suggestion was made that this mechanism could inactivate most vegetative cells and spores of the m/o at the initial stage of their spontaneous migration into the cosmos from the platforms where life has originated and evolved. The authors believe the Earth and Earth-like planets to be such platforms. Such a mechanism could restrict the application of the radiopanspermia hypothesis to the explanation of the origin of life on the Earth.

Nussinov, M. D.; Lysenko, S. V.

1983-12-01

215

Vacuum thermal insulation panel  

SciTech Connect

A vacuum thermal insulation panel comprises a pair of laminated plastic and aluminum sheets together with a plastic edge strip sealed to the edges of the sheets so as to define an evacuable volume in which a glass fiber mat is disposed. The insulation panel of the present invention takes advantage of the light-weight, low cost and low thermal conductivity of plastic materials to form an evacuable volume into which a glass fiber insulating mat is disposed for support of the panel which is evacuated to provide improved thermal insulation. Additionally, a gas permeation barrier is employed on the edge strip of the panel to minimize gas permeation at its edges. A metal foil layer provides gas permeation protection through the large surface areas of the sheets themselves.

Young, J.R.; Schreck, R.M.

1984-04-24

216

Future complete vacuum spacetimes  

E-print Network

In this paper we prove a global existence theorem, in the direction of cosmological expansion, for sufficiently small perturbations of a family of spatially compact variants of the $k=-1$ Friedmann--Robertson--Walker vacuum spacetime. We use a special gauge defined by constant mean curvature slicing and a spatial harmonic coordinate condition, and develop energy estimates through the use of the Bel-Robinson energy and its higher order generalizations. In addition to the smallness condition on the data, we need a topological constraint on the spatial manifold to exclude the possibility of a non--trivial moduli space of flat spacetime perturbations, since the latter could not be controlled by curvature--based energies such as those of Bel--Robinson type. Our results also demonstrate causal geodesic completeness of the perturbed spacetimes (in the expanding direction) and establish precise rates of decay towards the background solution which serves as an attractor asymptotically.

Lars Andersson; Vincent Moncrief

2003-03-11

217

Abdominal intrauterine vacuum aspiration.  

PubMed

Evaluating and "cleaning" of the uterine cavity is probably the most performed operation in women. It is done for several reasons: abortion, evaluation of irregular bleeding in premenopausal period, and postmenopausal bleeding. Abortion is undoubtedly the number one procedure with more than 44 million pregnancies terminated every year. This procedure should not be underestimated and a careful preoperative evaluation is needed. Ideally a sensitive pregnancy test should be done together with an ultrasound in order to confirm a uterine pregnancy, excluding extra-uterine pregnancy, and to detect genital and/or uterine malformations. Three out of four abortions are performed by surgical methods. Surgical methods include a sharp, blunt, and suction curettage. Suction curettage or vacuum aspiration is the preferred method. Despite the fact that it is a relative safe procedure with major complications in less than one percent of cases, it is still responsible for 13% of all maternal deaths. All the figures have not declined in the last decade. Trauma, perforation, and bleeding are a danger triage. When there is a perforation, a laparoscopy should be performed immediately, in order to detect intra-abdominal lacerations and bleeding. The bleeding should be stopped as soon as possible in order to not destabilize the patient. When there is a perforation in the uterus, this "entrance" can be used to perform the curettage. This is particularly useful if there is trauma of the isthmus and uterine wall, and it is difficult to identify the uterine canal. A curettage is a frequent performed procedure, which should not be underestimated. If there is a perforation in the uterus, then this opening can safely be used for vacuum aspiration. PMID:25134300

Tjalma, W A A

2014-01-01

218

Crystal growth and annealing method and apparatus  

DOEpatents

A method and apparatus for producing crystals that minimizes birefringence even at large crystal sizes, and is suitable for production of CaF.sub.2 crystals. The method of the present invention comprises annealing a crystal by maintaining a minimal temperature gradient in the crystal while slowly reducing the bulk temperature of the crystal. An apparatus according to the present invention includes a thermal control system added to a crystal growth and annealing apparatus, wherein the thermal control system allows a temperature gradient during crystal growth but minimizes the temperature gradient during crystal annealing. An embodiment of the present invention comprises a secondary heater incorporated into a conventional crystal growth and annealing apparatus. The secondary heater supplies heat to minimize the temperature gradients in the crystal during the annealing process. The secondary heater can mount near the bottom of the crucible to effectively maintain appropriate temperature gradients.

Gianoulakis, Steven E. (Albuquerque, NM); Sparrow, Robert (North Brookfield, MA)

2001-01-01

219

Reduced annealing temperatures in silicon solar cells  

NASA Technical Reports Server (NTRS)

Cells irradiated to a fluence of 5x10,000,000,000,000/square cm showed short circuit current on annealing at 200 C, with complete annealing occurring at 275 C. Cells irradiated to 100,000,000,000,000/square cm showed a reduction in annealing temperature from the usual 500 to 300 C. Annealing kinetic studies yield an activation energy of (1.5 + or - 2) eV for the low fluence, low temperature anneal. Comparison with activation energies previously obtained indicate that the presently obtained activation energy is consistent with the presence of either the divacancy or the carbon interstitial carbon substitutional pair, a result which agrees with the conclusion based on defect behavior in boron-doped silicon.

Weinberg, I.; Swartz, C. K.

1981-01-01

220

Coherent Phenomena in Photonic Crystals  

E-print Network

We study the spontaneous emission, the absorption and dispersion properties of a ${\\bf \\Lambda}$-type atom where one transition interacts near resonantly with a double-band photonic crystal. Assuming an isotropic dispersion relation near the band edges, we show that two distinct coherent phenomena can occur. First, the spontaneous emission spectrum of the adjacent free space transition obtains `dark lines' (zeroes in the spectrum). Second, the atom can become transparent to a probe laser field coupling to the adjacent free space transition.

Angelakis, D G; Knight, P L

2001-01-01

221

Coherent Phenomena in Photonic Crystals  

E-print Network

We study the spontaneous emission, the absorption and dispersion properties of a ${\\bf \\Lambda}$-type atom where one transition interacts near resonantly with a double-band photonic crystal. Assuming an isotropic dispersion relation near the band edges, we show that two distinct coherent phenomena can occur. First, the spontaneous emission spectrum of the adjacent free space transition obtains `dark lines' (zeroes in the spectrum). Second, the atom can become transparent to a probe laser field coupling to the adjacent free space transition.

D. G. Angelakis; E. Paspalakis; P. L. Knight

2000-09-26

222

Vapor explosion phenomena: Scaling considerations  

SciTech Connect

Past safety analyses considered the hazard from vapor explosions in a conservative manner where engineering judgment and conservative analyses were used to estimate the likelihood of nuclear reactor containment failure from explosion-induced missile generation [alpha-mode failure]. However, recent safety analyses may require less conservative methods to determine the hazard from vapor explosions; thus one may need to consider more detailed scaling of vapor explosion phenomena. This paper proposes particular scaling considerations for vapor explosions based on recent experimental results and that vapor explosions with prototypic reactor fuel material may be less of a hazard.

Corradini, M.L. [Univ. of Wisconsin, Madison, WI (United States)

1996-08-01

223

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

224

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

225

Vacuum pyrolysis of sugarcane bagasse  

Microsoft Academic Search

The objective of this study was to provide background data on sugarcane bagasse vacuum pyrolysis. Product yields and properties were investigated. Vacuum pyrolysis tests were performed at bench and pilot plant scales. The bagasse finest particles with a diameter smaller than 450 ?m were removed in order to overcome difficulties caused by their low density and high ash content. In

Abdelkader Chaala; Christian Roy

2002-01-01

226

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

227

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

228

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, John D. (Kennewick, WA); Gross, Mark E. (Pasco, WA)

1997-01-01

229

Vacuum Technology for Ion Sources  

E-print Network

The basic notions of vacuum technology for ion sources are presented, with emphasis on pressure profile calculation and choice of pumping technique. A Monte Carlo code (Molflow+) for the evaluation of conductances and the vacuum-electrical analogy for the calculation of time-dependent pressure variations are introduced. The specific case of the Linac4 H- source is reviewed.

Chiggiato, P

2013-01-01

230

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

231

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

232

Cosmology with decaying vacuum energy  

SciTech Connect

Motivated by recent attempts to solve the cosmological constant problem, we examine the observational consequences of a vacuum energy density which decays in time. For all times later than t approx. 1 sec, the ratio of the vacuum to the total energy density of the universe must be small. Although the vacuum cannot provide the ''missing mass'' required to close the universe today, its presence earlier in the history of the universe could have important consequences. We discuss restrictions on the vacuum energy arising from primordial nucleosynthesis, the microwave and gamma ray background spectra, and galaxy formation. A small vacuum component at the era of nucleosynthesis, 0.01 < rho/sub vac//rho/sup rad/ < 0.1, increase the number of allowed neutino species to N/sup nu/ > 5, but in some cases would severely distort the microwave spectrum. 9 refs., 3 figs.

Freese, K.; Adams, F.; Frieman, J.; Mottola, E.

1987-09-01

233

Bubbling the False Vacuum Away  

E-print Network

We investigate the role of nonperturbative, bubble-like inhomogeneities on the decay rate of false-vacuum states in two and three-dimensional scalar field theories. The inhomogeneities are induced by setting up large-amplitude oscillations of the field about the false vacuum as, for example, after a rapid quench or in certain models of cosmological inflation. We show that, for a wide range of parameters, the presence of large-amplitude bubble-like inhomogeneities greatly accelerates the decay rate, changing it from the well-known exponential suppression of homogeneous nucleation to a power-law suppression. It is argued that this fast, power-law vacuum decay -- known as resonant nucleation -- is promoted by the presence of long-lived oscillons among the nonperturbative fluctuations about the false vacuum. A phase diagram is obtained distinguishing three possible mechanisms for vacuum decay: homogeneous nucleation, resonant nucleation, and cross-over. Possible applications are briefly discussed.

Marcelo Gleiser; Barrett Rogers; Joel Thorarinson

2007-08-28

234

Crystal growth behaviour in Au-ZnO nanocomposite under different annealing environments and photoswitchability  

SciTech Connect

The growth of gold nanoparticles and ZnO nanorods in atom beam co-sputtered Au-ZnO nanocomposite (NC) system by annealing at two different ambient conditions is demonstrated in this work. Annealing in a furnace at 600 Degree-Sign C (air environment) confirmed the formation of ZnO nanorods surrounded with Au nanoparticles. In-situ annealing inside a transmission electron microscope (TEM) led to the formation of gold nanocrystals with different polygonal shapes. TEM micrographs were obtained in real time at intermediate temperatures of 300 Degree-Sign C, 420 Degree-Sign C, and 600 Degree-Sign C under vacuum. The growth mechanisms of Au nanocrystals and ZnO nanorods are discussed in the framework of Au-Zn eutectic and Zn-melting temperatures in vacuum and air, respectively. Current-voltage responses of Au-ZnO NC nanorods in dark as well as under light illumination have been investigated and photoswitching in Au-ZnO NC system is reported. The photoswitching has been discussed in terms of Au-ZnO band-diagram.

Mishra, Y. K.; Adelung, R. [Functional Nanomaterials, Institute for Materials Science, University of Kiel, Kaiserstrasse 2, 24143 Kiel (Germany); Chakravadhanula, V. S. K.; Hrkac, V.; Kienle, L. [Synthesis and Real Structure, Institute for Materials Science, University of Kiel, Kaiserstrasse 2, 24143 Kiel (Germany); Jebril, S. [Multicomponent Materials, Institute for Materials Science, University of Kiel, Kaiserstrasse 2, 24143 Kiel (Germany); Agarwal, D. C.; Avasthi, D. K. [Inter University Accelerator Centre, Post Box 10502, New Delhi 110067 (India); Mohapatra, S. [University School of Basic and Applied Sciences, GGS Indraprastha University, Dwaraka, New Delhi 110075 (India)

2012-09-15

235

Polarization rotation for light propagating non-parallel to a magnetic field in QED vacuum and in a dilute electron gas  

Microsoft Academic Search

The rotation of the polarization vector for light propagating perpendicular to an external constant external magnetic field $B$, is calculated in quantum vacuum, where it leads to different photon eigenmodes of the magnetized photon self-energy tensor for polarizations along and orthogonal to $B$ (Cotton-Mouton effect in QED vacuum). Its analogies and differences with Faraday effect are discussed and both phenomena

H. Perez Rojas; E. Rodriguez Querts

2007-01-01

236

Can the Vacuum Be Engineered for Spaceight Applications? Overview of Theory and Experiments1  

Microsoft Academic Search

Quantum theory predicts, and experiments verify, that empty space (the vacuum) contains an enormous residual background energy known as zero-point energy (ZPE). Originally thought to be of significance only for such esoteric concerns as small perturbations to atomic emission processes, it is now known to play a role in large-scale phenomena of interest to technologists as well, such as the

H. E. PUTHOFF

237

Deformation and annealing response of TD-nickel chromium  

NASA Technical Reports Server (NTRS)

The recrystallization and grain growth processes occurring in TD-NiCr were examined with respect to deformation severity, annealing time, and temperature. Results indicated that two different annealing responses of TD-NiCr are possible, depending on the initial state and processing history prior to annealing. As-received sheet showed a dramatic increase in grain size with decreasing annealing temperature, whereas sheet prior-annealed at 1316 C for 1 hr exhibited very little variation with subsequent annealing temperature.

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

1975-01-01

238

Vacuum energy, antigravity, and modern cosmology  

E-print Network

Vacuum energy, antigravity, and modern cosmology John Peacock, University of Edinburgh Loretto and zero- point energy (inevitable from uncertainty principle) ­ not the only contribution to vacuum energy;Vacuum energy: Einstein's missed chance Now: `Dark Energy' can cause the

Peacock, John

239

Phase balancing using simulated annealing  

SciTech Connect

Deregulation eliminates the boundary of the territory of the monopoly power industry. Competition forces utilities to improve power quality as well as to reduce investment and operation costs. Feeder imbalance describes a situation in which the voltages of a three-phase voltage source are not identical in magnitude, or the phase differences between them are not 120 electrical degrees, or both. It affects motors and other devices that depend upon a well-balanced three-phase voltage source. Phase balancing is to make the voltages balanced at each load point of the feeder. Phase swapping is a direct approach for phase balancing with the minimum cost. Phase balancing can enhance utilities' competitive capability by improving reliability, quality, and reducing costs. Therefore, phase balancing optimization is nowadays receiving more attention in the power industry, especially in today's deregulating environments. The non-linear effects, such as, voltage drops and energy losses, make the problem difficult to solve. This paper introduces Simulated Annealing as an effective method to solve a power distribution phase balancing problem with its non-linear effects.

Zhu, J.; Bilbro, G.; Chow, M.Y.

1999-11-01

240

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

241

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

242

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

243

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

244

Vacuum energy and cosmological evolution  

NASA Astrophysics Data System (ADS)

An expanding universe is not expected to have a static vacuum energy density. The so-called cosmological constant ? 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 ??˜R˜H2. 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 ?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.

Solà, Joan

2014-07-01

245

Percolation phenomena by computer simulation  

SciTech Connect

The microstructure of cement-based materials is determined by the chemical nature and amounts of the original constituents, and the succeeding chemical hydration process. An aspect of the microstructure that is important in determining properties is how these products are arranged topologically in space. In particular, how each product phase becomes connected or disconnected (percolation threshold) plays a large role in such important properties of these porous materials as ionic diffusion, electrical conductivity, and fluid permeability. We use computer models to determine the important percolation thresholds in portland cement-based materials, covering connectivity phenomena from length scales of micrometers to meters. We show how the overall behavior of this material, from processing to final use, may be described by its percolation thresholds.

Garboczi, E.J.; Bentz, D.P. [National Institute of Standards and Technology, Gaithersburg, MD (United States)

1995-12-31

246

Relaxation phenomena in cryogenic electrolytes  

NASA Astrophysics Data System (ADS)

Proposed is a scenario for the development of observed relaxation phenomena in a cryogenic electrolyte with the structure of "liquid hydrogen + injected ions." Ions of one sign are generated in the bulk of liquid hydrogen in the presence of external field E? by a stationary radioactive source of ± ions at the bottom of a vessel. After accumulation near the free surface of the liquid with a finite density ns the ions can break its stability producing a pulse of ion current to the collector located above the liquid surface. The outlined process is periodically repeated. Its period contains information on the ion mobility and, which is most interesting, on dissociation (association) processes occurring in a system of charged particles placed in an external field. The cryogenic problem is a good model for dissociation in the presence of external field occurring in normal electrolytes without any external ion sources.

Shikin, V.; Chikina, I.; Nazin, S.

2013-06-01

247

48 Optical Illusions & Visual Phenomena  

NSDL National Science Digital Library

Have you ever wondered how different optical illusions work? This fun, informative, and very cool website developed by ophthalmologist Dr. Michael Bach of the University of Freiburg's Medical School introduces 48 interactive visual illusions and phenomena. The illusions are animated and accompanied by explanations that help visitors make sense of their perceptual responses. Major illusion categories include: Motion & Time, Luminance & Contrast, Colour, Cognitive, and more. The site is still in progress, and Dr. Bach encourages both general feedback, and additional scientific information for improving the illusion explanations. The second site, also from Professor Bach, presents site users with an interactive, online Visual Acuity Test. Note: The Contrast component of the Test has yet to be implemented.

248

Numerical study on sublimation–condensation phenomena during microwave freeze drying  

Microsoft Academic Search

A sublimation–condensation model is developed for freeze drying of unsaturated porous media. The governing equations describing the drying process are solved numerically with variable time step finite-difference method. The sublimation–condensation phenomena during microwave freeze drying are studied numerically for different operating conditions including electric field strength, sample thickness, and vacuum pressure. The results show that the sublimation–condensation effects depend on

Zhao Hui Wang; Ming Heng Shi

1998-01-01

249

Eects of Post Deposition Treatments on Vacuum Evaporated CdTe Thin Films and CdS=CdTe Heterojunction Devices  

Microsoft Academic Search

CdTe, CdS thin films and n-CdS\\/p-CdTe heterostructures have been prepared by conventional vacuum evaporation technique. Some post deposition treatments to optimize the device efficiency have been analyzed and the effects of the individual process steps on the material and device properties were investigated. Annealing in air with and without CdCl2-treatment decreased the CdTe resistivity. The CdCl2-dip followed by annealing in

Habibe Bayhan; Çiðdem Erçelebý

1998-01-01

250

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

251

The localized quantum vacuum field  

NASA Astrophysics Data System (ADS)

A model for the localized quantum vacuum is proposed in which the zero-point energy (ZPE) of the quantum electromagnetic field originates in energy- and momentum-conserving transitions of material systems from their ground state to an unstable state with negative energy. These transitions are accompanied by emissions and re-absorptions of real photons, which generate a localized quantum vacuum in the neighborhood of material systems. The model could help resolve the cosmological paradox associated with the ZPE of electromagnetic fields, while reclaiming quantum effects associated with quantum vacuum such as the Casimir effect and the Lamb shift. It also offers a new insight into the Zitterbewegung of material particles.

Dragoman, D.

2008-03-01

252

Vacuum Function Operation and Systems  

NSDL National Science Digital Library

The understanding of vacuum function and systems is essential for students and employees working within the micro- and nanofabrication industry. This presentation/webinar highlights the use, construction, and examples of current vacuum technology systems today. Prepared by WHO, of the Nanotechnology Applications and Career Knowledge (NACK), a National ATE Center, this presentation provides material presented from the instructor/engineer viewpoint. Discussions include vacuum pump function, gauge use and ranges, applicable design considerations, as well as insight on cost and equipment training methodologies that have been utilized by the NACK Center. This site requires a free log-in to access.

2009-10-06

253

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

254

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

255

Higher-order scalar interactions and SM vacuum stability  

E-print Network

Investigation of the structure of the Standard Model effective potential at very large field strengths opens a window towards new phenomena and can reveal properties of the UV completion of the SM. The map of the lifetimes of the vacua of the SM enhanced by nonrenormalizable scalar couplings has been compiled to show how new interactions modify stability of the electroweak vacuum. Whereas it is possible to stabilize the SM by adding Planck scale suppressed interactions and taking into account running of the new couplings, the generic effect is shortening the lifetime and hence further destabilisation of the SM electroweak vacuum. These findings have been illustrated with phase diagrams of modified SM-like models. It has been demonstrated that stabilisation can be achieved by lowering the suppression scale of higher order operators while picking up such combinations of new couplings, which do not deepen the new minima of the potential. Our results show the dependence of the lifetime of the electroweak minimum ...

Lalak, Zygmunt; Olszewski, Pawel

2014-01-01

256

Enthalpy relaxation and annealing effect in polystyrene.  

PubMed

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. PMID:23944484

Sakatsuji, Waki; Konishi, Takashi; Miyamoto, Yoshihisa

2013-07-01

257

Fuzzy Modeling with Adaptive Simulated Annealing  

E-print Network

approach uses Takagi-Sugeno models and Adaptive Simulated Annealing (ASA) to .... At first , and to investigate the efficiency of the ASA method in this kind of .... Kohonen SOM ( Self Organizing Map ) to realize the clustering ( or vector.

258

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

259

Ultrathin films of lead oxide on gold: Dependence of stoichiometry, stability and thickness on O 2 pressure and annealing temperature  

Microsoft Academic Search

Ultrathin oxide films grown in vacuum are important in many industrial areas, including microelectronics and heterogeneous catalysis. In this paper, the dependence of oxide stoichiometry, growth kinetics, thickness and stability on O2 pressure and annealing temperature are explored using a high-stability quartz-crystal microbalance and Auger spectroscopy, for the oxidation of lead on gold as a model system. The oxide thickness

L. Bouzidi; A. J. Slavin

2005-01-01

260

A study of magnetically annealed ferromagnetic materials  

E-print Network

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... OF SCIENCE August 1961 Major Subject: Electrical Engineering A STUDY OF MAGNETICALLY ANNEALED FERROMAGNETIC MATERIALS A Thesis By 0 ca o o W C DOMINGO RAMOS App ved as to style and content by: r Ct- Chairman of Co ittee Head of Department...

Ramos, Domingo

2012-06-07

261

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

262

Annealed CVD molybdenum thin film surface  

DOEpatents

Molybdenum thin films deposited by pyrolytic decomposition of Mo(CO).sub.6 attain, after anneal in a reducing atmosphere at temperatures greater than 700.degree. C., infrared reflectance values greater than reflectance of supersmooth bulk molybdenum. Black molybdenum films deposited under oxidizing conditions and annealed, when covered with an anti-reflecting coating, approach the ideal solar collector characteristic of visible light absorber and infrared energy reflector.

Carver, Gary E. (Tucson, AZ); Seraphin, Bernhard O. (Tucson, AZ)

1984-01-01

263

Mirowave annealing of silicon nitride materials  

SciTech Connect

Dense silicon nitride-based ceramics were microwave annealed to determine if microwave heating offers advantages over conventional heating for the enhancement of the high temperature creep resistance. Gas pressure sintered silicon nitride (GPS-SN) and sintered reaction-bonded silicon nitride (SRBSN) were heated in microwave or graphite element furnaces at 1150{degrees}C and 1600{degrees}C. Annealed materials were characterized for the room and high temperature flexural strengths, room temperature fracture toughness values, and high temperature creep properties. In addition, SEM analyses were performed to study grain growth and other microstructural changes. The results of this study showed that both types of furnace anneals at 1150{degrees}C lowered the room temperature strength and toughness values of both SRBSN and GPS-SN materials; however, the anneal treatments at 1600{degrees}C had little effect on the room temperature properties. Both the SRBSN and GPS-SN control and annealed samples had reduced high temperature fast fracture strengths, when compared to the room temperature strengths. Creep tests at 1200{degrees}C indicated that both the SRBSN and the GPS-SN materials that were annealed by microwave heating at I 150{degrees}C for 20 h showed enhanced creep resistance, when compared to unheated controls and conventionally heated materials. No qualitative differences were seen in the microstructures of the SRBSN and the GPS-SN materials which could account for the differences in the creep properties of the annealed materials. Additional experimental work is in progress to further understand the mechanisms for the enhanced creep properties of silicon nitride materials annealed by microwave heating.

Kiggans, J.O. Jr.; Montgomery, F.C.; Tiegs, T.N. [and others] [and others

1997-08-01

264

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

SciTech Connect

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 {approx}10{sup 8} A/cm{sup 2}. 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. [Electrical Discharge and Plasma Laboratory, Tel Aviv University, 69978 Tel Aviv (Israel); Oreshkin, V. I.; Russkikh, A. G.; Chaikovskii, S. A.; Labetskii, A. Yu.; Ratakhin, N. A.; Shishlov, A. V. [Institute of High Current Electronics, Russian Academy of Science, Tomsk (Russian Federation)

2008-01-15

265

Long-term microstructural stability of oxide-dispersion strengthened Eurofer steel annealed at 800 °C  

NASA Astrophysics Data System (ADS)

Oxide-dispersion strengthened ferritic martensitic steels such as ODS-Eurofer grade are good candidates for structural applications in future fusion power reactors. Long-term annealing treatments in vacuum were carried out in cold-rolled samples (80% reduction in thickness) from 1 h up to 4320 h (6 months) at 800 °C, i.e. the maximum temperature in the ferritic phase field, to follow its softening behavior. The microstructural stability of this steel was mapped using several characterization techniques including scanning electron microscopy, transmission electron microscopy, electron backscatter diffraction, Vickers microhardness testing, X-ray diffraction texture measurements, low-temperature electrical resistivity, and magnetic coercive field measurements. ODS-Eurofer steel displays good microstructural stability. Discontinuous recrystallization occurs at the early stages of annealing resulting in a low volume fraction of recrystallized grains. Extended recovery is the predominant softening mechanism at this temperature for longer times.

Zilnyk, K. D.; Sandim, H. R. Z.; Bolmaro, R. E.; Lindau, R.; Möslang, A.; Kostka, A.; Raabe, D.

2014-05-01

266

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

267

Comparative Study of the Performance of Quantum Annealing and Simulated Annealing  

E-print Network

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 non-equilibrium dynamics of the one-dimensional Ising model is provided through the classical-to-quantum mapping.

Hidetoshi Nishimori; Junichi Tsuda; Sergey Knysh

2014-09-23

268

Electromechanical phenomena in semiconductor nanostructures  

NASA Astrophysics Data System (ADS)

Electromechanical phenomena in semiconductors are still poorly studied from a fundamental and an applied science perspective, even though significant strides have been made in the last decade or so. Indeed, most current electromechanical devices are based on ferroelectric oxides. Yet, the importance of the effect in certain semiconductors is being increasingly recognized. For instance, the magnitude of the electric field in an AlN/GaN nanostructure can reach 1-10 MV/cm. In fact, the basic functioning of an (0001) AlGaN/GaN high electron mobility transistor is due to the two-dimensional electron gas formed at the material interface by the polarization fields. The goal of this review is to inform the reader of some of the recent developments in the field for nanostructures and to point out still open questions. Examples of recent work that involves the piezoelectric and pyroelectric effects in semiconductors include: the study of the optoelectronic properties of III-nitrides quantum wells and dots, the current controversy regarding the importance of the nonlinear piezoelectric effect, energy harvesting using ZnO nanowires as a piezoelectric nanogenerator, the use of piezoelectric materials in surface acoustic wave devices, and the appropriateness of various models for analyzing electromechanical effects. Piezoelectric materials such as GaN and ZnO are gaining more and more importance for energy-related applications; examples include high-brightness light-emitting diodes for white lighting, high-electron mobility transistors, and nanogenerators. Indeed, it remains to be demonstrated whether these materials could be the ideal multifunctional materials. The solutions to these and other related problems will not only lead to a better understanding of the basic physics of these materials, but will validate new characterization tools, and advance the development of new and better devices. We will restrict ourselves to nanostructures in the current article even though the measurements and calculations of the bulk electromechanical coefficients remain challenging. Much of the literature has focused on InGaN/GaN, AlGaN/GaN, ZnMgO/ZnO, and ZnCdO/ZnO quantum wells, and InAs/GaAs and AlGaN/AlN quantum dots for their optoelectronic properties; and work on the bending of nanowires have been mostly for GaN and ZnO nanowires. We hope the present review article will stimulate further research into the field of electromechanical phenomena and help in the development of applications.

Lew Yan Voon, L. C.; Willatzen, M.

2011-02-01

269

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

270

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 d...

Sola, Joan

2014-01-01

271

Cold cathode vacuum gauging system  

DOEpatents

A vacuum gauging system of the cold cathode type is provided for measuring the pressure of a plurality of separate vacuum systems, such as in a gas centrifuge cascade. Each casing is fitted with a gauge tube assembly which communicates with the vacuum system in the centrifuge casing. Each gauge tube contains an anode which may be in the form of a slender rod or wire hoop and a cathode which may be formed by the wall of the gauge tube. The tube is provided with an insulated high voltage connector to the anode which has a terminal for external connection outside the vacuum casing. The tube extends from the casing so that a portable magnet assembly may be inserted about the tube to provide a magnetic field in the area between the anode and cathode necessary for pressure measurements in a cold cathode-type vacuum gauge arrangement. The portable magnetic assembly is provided with a connector which engages the external high voltage terminal for providing power to the anode within in the gauge tube. Measurement is made in the same manner as the prior cold cathode gauges in that the current through the anode to the cathode is measured as an indication of the pressure. By providing the portable magnetic assembly, a considerable savings in cost, installation, and maintenance of vacuum gauges for pressure measurement in a gas centrifuge cascade is realizable.

Denny, Edward C. (Knoxville, TN)

2004-03-09

272

Technical specification for vacuum systems  

SciTech Connect

The vacuum systems at the Stanford Linear Accelerator Center (SLAC) are primarily of all-metal construction and operate at pressures from 10/sup -5/ to 10/sup -11/ Torr. The primary gas loads during operation result from thermal desorption and beam-induced desorption from the vacuum chamber walls. These desorption rates can be extremely high in the case of hydrocarbons and other contaminants. These specifications place a major emphasis on eliminating contamination sources. The specifications and procedures have been written to insure the cleanliness and vacuum integrity of all SLAC vacuum systems, and to assist personnel involved with SLAC vacuum systems in choosing and designing components that are compatible with existing systems and meet the quality and reliability of SLAC vacuum standards. The specification includes requirements on design, procurement, fabrication, chemical cleaning, clean room practices, welding and brazing, helium leak testing, residual gas analyzer testing, bakeout, venting, and pumpdown. Also appended are specifications regarding acceptable vendors, isopropyl alcohol, bakeable valve cleaning procedure, mechanical engineering safety inspection, notes on synchrotron radiation, and specifications of numerous individual components. (LEW)

Khaw, J. (ed.)

1987-01-01

273

Optical phenomena in the open air  

NASA Astrophysics Data System (ADS)

Objects readily observed by everyone in the open air constitute fascinating phenomena. However, details on the origin of such phenomena like rainbows, halos, glories, lightning and northern lights often stay in the background whereas the combination of both observation and background knowledge will open an even more fascinating view. This article summarises the underlying physical principles of these phenomena and addresses the characteristics they have in common as well as their main differences.

Fantz, U.

2004-02-01

274

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

275

Proton damage annealing kinetics in silicon solar cells  

NASA Technical Reports Server (NTRS)

Proton damage annealing as a method for prolonging the life of solar power systems in space is discussed. Variables are minimized and fundamental characteristics of proton damage annealing are considered. The usefulness of annealing for prolonging space missions is evaluated. A preliminary determination of optimum annealing conditions is made, and base data provided for more detailed research programs.

Horne, W. E.; Arimura, I.; Day, A. C.

1980-01-01

276

Bleed Hole Flow Phenomena Studied  

NASA Technical Reports Server (NTRS)

Boundary-layer bleed is an invaluable tool for controlling the airflow in supersonic aircraft engine inlets. Incoming air is decelerated to subsonic speeds prior to entering the compressor via a series of oblique shocks. The low momentum flow in the boundary layer interacts with these shocks, growing in thickness and, under some conditions, leading to flow separation. To remedy this, bleed holes are strategically located to remove mass from the boundary layer, reducing its thickness and helping to maintain uniform flow to the compressor. The bleed requirements for any inlet design are unique and must be validated by extensive wind tunnel testing to optimize performance and efficiency. To accelerate this process and reduce cost, researchers at the NASA Lewis Research Center initiated an experimental program to study the flow phenomena associated with bleed holes. Knowledge of these flow properties will be incorporated into computational fluid dynamics (CFD) models that will aid engine inlet designers in optimizing bleed configurations before any hardware is fabricated. This ongoing investigation is currently examining two hole geometries, 90 and 20 (both with 5-mm diameters), and various flow features.

1997-01-01

277

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

NASA Astrophysics Data System (ADS)

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 SiO2/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.; Cren, T.; Debontridder, F.; Brun, C.; Veshchunov, I. S.; Skryabina, O. V.; Rusanov, A. Yu.; Roditchev, D.

2014-04-01

278

Vacuum Thrust Optimised Expansion Deflection Nozzles  

NASA Astrophysics Data System (ADS)

ED nozzles have long been considered for launch vehicle applications, due to their postulated twin benefits of reduced length and altitude compensating capability. However, the difficulties involved in modelling the inviscid/viscous jet boundaries and associated flow phenomena during wake closure, have prevented the creation of a reliable method for the prediction of the performance characteristics of the type through atmospheric flight. However, if the operating regime of the nozzle is restricted to vacuum conditions (e.g. upper stages, and OTVs, etc), the wake region of the ED nozzle is permanently closed. Under these circumstances, the prediction of the pressure distribution along the viscous/inviscid flow boundary, and the complex interaction of the fluid flows during wake closure, becomes unnecessary. Therefore thrust calculation may be accomplished by conventional techniques, provided reliable methods are available for the prediction of the flow in the throat region (which may be arbitrarily displaced and inclined to the axis of revolution), and estimation of the pressure acting on the base of the central pintle. Prediction of ED nozzle throat flows has been accomplished by the use of CFD techniques, described in a previous paper. The analysis in this paper has been extended to complete nozzles by including a conventional method of characteristics based optimisation routine for the outer shroud contour, and a semi-empirical method for prediction of pintle base pressures. A brief parametric study is presented, outlining the effects of throat configuration (including throat wall radii, and radial displacement and inclination) on the performance of axisymmetric and planar ED nozzles under vacuum conditions. Whilst the method used for base pressure prediction requires several simplifying assumptions which affect the accuracy, results from an ongoing experimental program are reducing this uncertainty. Further as nozzles designed for vacuum operation are likely to have extremely high area ratios to maximise thrust coefficient, the relative magnitude of the pintle base pressure is small compared to the forces generated on the shroud, reducing the sensitivity of overall thrust calculations to errors in base pressure prediction. A comparison of thrust performance of bell and ED nozzles reveals that considerable reductions in length are possible, in the region of 30%. By implication this should result in a significant lowering of system mass. This conclusion is further supported by consideration of the unrealistic worst case scenario, which is the assumption of zero thrust contribution from the pintle. This analysis still produces length savings of over 20% when compared to conventional optimised bell nozzles.

Taylor, N. V.; Hempsell, C. M.

2002-01-01

279

EBSD coupled to SEM in situ annealing for assessing recrystallization and grain growth mechanisms in pure tantalum.  

PubMed

An in situ annealing stage has been developed in-house and integrated in the chamber of a Scanning Electron Microscope equipped with an Electron BackScattered Diffraction system. Based on the Joule effect, this device can reach the temperature of 1200°C at heating rates up to 100°C/s, avoiding microstructural evolutions during heating. A high-purity tantalum deformed sample has been annealed at variable temperature in the range 750°C-1030°C, and classical mechanisms of microstructural evolutions such as recrystallization and grain coarsening phenomena have been observed. Quantitative measurements of grain growth rates provide an estimate of the mean grain boundary mobility, which is consistent with the value estimated from physical parameters reported for that material. In situ annealing therefore appears to be suited for complementing bulk measurements at relatively high temperatures, in the context of recrystallization and grain growth in such a single-phase material. PMID:23521093

Kerisit, C; Logé, R E; Jacomet, S; Llorca, V; Bozzolo, N

2013-06-01

280

Probability distribution of the vacuum energy density  

SciTech Connect

As the vacuum state of a quantum field is not an eigenstate of the Hamiltonian density, the vacuum energy density can be represented as a random variable. We present an analytical calculation of the probability distribution of the vacuum energy density for real and complex massless scalar fields in Minkowski space. The obtained probability distributions are broad and the vacuum expectation value of the Hamiltonian density is not fully representative of the vacuum energy density.

Duplancic, Goran; Stefancic, Hrvoje [Theoretical Physics Division, Rudjer Boskovic Institute, P.O. Box 180, HR-10002 Zagreb (Croatia); Glavan, Drazen [Department of Physics, Faculty of Science, University of Zagreb, P.O. Box 331, HR-10002 Zagreb (Croatia)

2010-12-15

281

Finite Time Vacuum Survival Amplitude and Vacuum Energy Decay  

E-print Network

The problem of the vacuum energy decay is studied for both signs of the cosmological constant, through the analysis of the vacuum survival amplitude, defined in terms of the {\\em conformal time}, $z$, by ${\\mathcal A}(z,z^\\prime)\\equiv $. Transition amplitudes are computed for finite time-span, $Z\\equiv z^\\prime-z$, and their {\\em late time} behavior (directly related to the putative decay width of the state) as well as the transients are discussed up to first order in the coupling constant, $\\lambda$.

Enrique Álvarez; Roberto Vidal

2011-07-15

282

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

283

films on silicon at different annealing temperatures  

NASA Astrophysics Data System (ADS)

Thermal atomic layer-deposited (ALD) aluminum oxide (Al2O3) acquires high negative fixed charge density ( Q f) and sufficiently low interface trap density after annealing, which enables excellent surface passivation for crystalline silicon. Q f can be controlled by varying the annealing temperatures. In this study, the effect of the annealing temperature of thermal ALD Al2O3 films on p-type Czochralski silicon wafers was investigated. Corona charging measurements revealed that the Q f obtained at 300°C did not significantly affect passivation. The interface-trapping density markedly increased at high annealing temperature (>600°C) and degraded the surface passivation even at a high Q f. Negatively charged or neutral vacancies were found in the samples annealed at 300°C, 500°C, and 750°C using positron annihilation techniques. The Al defect density in the bulk film and the vacancy density near the SiO x /Si interface region decreased with increased temperature. Measurement results of Q f proved that the Al vacancy of the bulk film may not be related to Q f. The defect density in the SiO x region affected the chemical passivation, but other factors may dominantly influence chemical passivation at 750°C.

Zhao, Yan; Zhou, Chunlan; Zhang, Xiang; Zhang, Peng; Dou, Yanan; Wang, Wenjing; Cao, Xingzhong; Wang, Baoyi; Tang, Yehua; Zhou, Su

2013-03-01

284

EMERGENT PHENOMENA IN GENETIC PROGRAMMING LEE ALTENBERG  

E-print Network

1 EMERGENT PHENOMENA IN GENETIC PROGRAMMING LEE ALTENBERG Institute of Statistics and Decision and algorith- mic properties of the tree-structured representation, both the genetics and representation can various emergent phenomena, pri- mary of which is adaptation. In genetic programming, because of the inde

Fernandez, Thomas

285

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

286

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

287

Coupled quintessence and vacuum decay  

NASA Astrophysics Data System (ADS)

We discuss observational consequences of a class of cosmological models characterized by the dilution of pressureless matter attenuated with respect to the usual a-3 scaling due to the decay of vacuum energy. We carry out a joint statistical analysis of observational data from the new gold sample of 182 SNe Ia, recent estimates of the cosmic microwave background shift parameter, and baryon acoustic oscillations measurements from the SDSS to show that such models favor the decay of vacuum only into the dark matter sector, and that the separately conserved baryons cannot be neglected. In order to explore ways to more fundamentally motivate these models, we also derive a coupled scalar field version for this general class of vacuum decay scenarios.

Costa, F. E. M.; Alcaniz, J. S.; Maia, J. M. F.

2008-04-01

288

Impact of rapid thermal annealing on structural, optical and electrical properties of DC sputtered doped and co-doped ZnO thin film  

NASA Astrophysics Data System (ADS)

We report a crucial change in structural properties which dramatically modified optical and electrical properties in annealed aluminium-boron and gallium-aluminum co-doped ZnO thin films grown using DC magnetron sputtering. Under vacuum, ambient films were annealed at 600 °C for 2 min and it was found that the transmission of annealed samples improved compared to pristine, doped, and co-doped ZnO thin films. The X-ray diffraction (XRD) patterns of pristine films exhibits a preferable growth orientation in <002> phases, however, after annealing signature of other peaks became prominent. Moreover, slender increase in crystallite size was also observed from XRD analysis. The surface morphology was studied using scanning electron microscopy (SEM). The surface morphology exhibits different structure which depending on the growth temperature was discussed in detail. The electrical properties viz. resistivity, mobility, and carrier concentration of both pristine and annealed ZnO thin films were measured at room temperature. An enhancement in the electrical properties of doped and co-doped ZnO thin films was noted after annealing. More significantly, it was found that annealed thin films showed the resistivity of the order ˜10-4 ohm cm with the enhanced optical transmittance. Such a transparent and conducting zinc-oxide thin film can be used as a window layer in solar cell.

Gupta, Chandan Ashis; Mangal, Sutanu; Singh, Udai P.

2014-01-01

289

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

290

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

291

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

292

Mass Dependence of Vacuum Energy  

E-print Network

The regularized vacuum energy (or energy density) of a quantum field subjected to static external conditions is shown to satisfy a certain partial differential equation with respect to two variables, the mass and the "time" (ultraviolet cutoff parameter). The equation is solved to provide integral expressions for the regularized energy (more precisely, the cylinder kernel) at positive mass in terms of that for zero mass. Alternatively, for fixed positive mass all coefficients in the short-time asymptotics of the regularized energy can be obtained recursively from the first nontrivial coefficient, which is the renormalized vacuum energy.

S. A. Fulling

2005-07-05

293

Particle description of zero energy vacuum. II. Basic vacuum systems  

E-print Network

We describe vacuum as a system of virtual particles, some of which have negative energies. Any system of vacuum particles is a part of a keneme, i.e. of a system of n particles which can, without violating the conservation laws, annihilate in the strict sense of the word (transform into nothing). A keneme is a homogeneous system, i.e. its state is invariant by all transformations of the invariance group. But a homogeneous system is not necessarily a keneme. In the simple case of a spin system, where the invariance group is SU(2), a homogeneous system is a system whose total spin is unpolarized; a keneme is a system whose total spin is zero. The state of a homogeneous system is described by a statistical operator with infinite trace (von Neumann), to which corresponds a characteristic distribution. The characteristic distributions of the homogeneous systems of vacuum are defined and studied. Finally it is shown how this description of vacuum can be used to solve the frame problem posed in (I).

J. Y. Grandpeix; F. Lurcat

2001-06-25

294

Simulated Quantum Annealing by the Real-time Evolution  

NASA Astrophysics Data System (ADS)

It has been revealed during the last few decades that approaches originating from the physics succeeds in solving combinatorial optimization problems [1]. The simulated thermal annealing method created such a close relation between physics and optimization problems. The quantum annealing method was born as an analogue of conventional thermal annealing [2, 3]. In spite of its origin, the mechanism and formulation of quantum annealing are fundamentally different from those of simulated thermal annealing. The former is based on the dynamics in quantum mechanics, while the latter is on the classical dynamics. Furthermore the quantum annealing is basically formulated for zero temperature in contrast to finite temperature simulation of thermal annealing. Because of these differences, the quantum annealing is expected as a novel efficient method for optimization problems. In practice, an experiment using spin-glass material has shown the superiority of the quantum annealing over the thermal annealing [4]. Simulations by means of the pathintegral quantum Monte-Carlo have also shown that an optimization in the spin-glass model is achieved in a less time by the quantum annealing than by the thermal annealing [5]. However study on quantum annealing is insu.cient for establishing this method as an effective optimization method. We focus in this paper on some basic features and a new method for implementation of the simulated quantum annealing.

Suzuki, Sei; Okada, Masato

295

Annealing Increases Stability Of Iridium Thermocouples  

NASA Technical Reports Server (NTRS)

Metallurgical studies carried out on samples of iridium versus iridium/40-percent rhodium thermocouples in condition received from manufacturer. Metallurgical studies included x-ray, macroscopic, resistance, and metallographic studies. Revealed large amount of internal stress caused by cold-working during manufacturing, and large number of segregations and inhomogeneities. Samples annealed in furnace at temperatures from 1,000 to 2,000 degree C for intervals up to 1 h to study effects of heat treatment. Wire annealed by this procedure found to be ductile.

Germain, Edward F.; Daryabeigi, Kamran; Alderfer, David W.; Wright, Robert E.; Ahmed, Shaffiq

1989-01-01

296

Parameterization of annealing kinetics in pharmaceutical glasses.  

PubMed

Numerical simulations indicate that neglecting the canonical nonlinearity of glassy-state annealing kinetics in pharmaceutical (and other) glasses leads to good KWW fits to the dependence of enthalpy on annealing time, but with spurious KWW parameters that are affected by nonlinearity. A simplified treatment of nonlinearity that uses the Struik shift factor is found to be a useful approximation for these analyses, and can account for previously reported differences between linear and nonlinear KWW parameters (Kawakami K, Pikal MJ. 2005. J Pharm Sci 94:948-965). PMID:23661359

Hodge, Ian M

2013-07-01

297

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

298

Improved zircon fission-track annealing model based on reevaluation of annealing data  

NASA Astrophysics Data System (ADS)

The thermal recovery (annealing) of mineral structure modified by the passage of fission fragments has long been studied by the etching technique. In minerals like apatite and zircon, the annealing kinetics are fairly well constrained from the hour to the million-year timescale and have been described by empirical and semi-empirical equations. On the other hand, laboratory experiments, in which ion beams interact with minerals and synthetic ceramics, have shown that there is a threshold temperature beyond which thermal recovery impedes ion-induced amorphization. In this work, it is assumed that this behavior can be extended to the annealing of fission tracks in minerals. It is proposed that there is a threshold temperature, T 0, beyond which fission tracks are erased within a time t 0, which is independent of the current state of lattice deformation. This implies that iso-annealing curves should converge to a fanning point in the Arrhenius pseudo-space (ln t vs. 1/ T). Based on the proposed hypothesis, and laboratory and geological data, annealing equations are reevaluated. The geological timescale estimations of a model arising from this study are discussed through the calculation of partial annealing zone and closure temperature, and comparison with geological sample constraints found in literature. It is shown that the predictions given by this model are closer to field data on closure temperature and partial annealing zone than predictions given by previous models.

Guedes, S.; Moreira, P. A. F. P.; Devanathan, R.; Weber, W. J.; Hadler, J. C.

2013-02-01

299

Improved zircon fission-track annealing model based on reevaluation of annealing data  

SciTech Connect

The thermal recovery (annealing) of mineral structure modified by the passage of fission fragments has long been studied by the etching technique. In minerals like apatite and zircon, the annealing kinetics are fairly well constrained from the hour to the million-year timescale and have been described by empirical and semi-empirical equations. On the other hand, laboratory experiments, in which ion beams interact with minerals and synthetic ceramics, have shown that there is a threshold temperature beyond which thermal recovery impedes ion-induced amorphization. In this work, it is assumed that this behavior can be extended to the annealing of fission tracks in minerals. It is proposed that there is a threshold temperature, T 0, beyond which fission tracks are erased within a time t 0, which is independent of the current state of lattice deformation. This implies that iso-annealing curves should converge to a fanning point in the Arrhenius pseudo-space (ln t vs. 1/T). Based on the proposed hypothesis, and laboratory and geological data, annealing equations are reevaluated. The geological timescale estimations of a model arising from this study are discussed through the calculation of partial annealing zone and closure temperature, and comparison with geological sample constraints found in literature. It is shown that the predictions given by this model are closer to field data on closure temperature and partial annealing zone than predictions given by previous models.

Guedes, S.; Moreira, Pedro; Devanathan, Ramaswami; Weber, William J.; Hadler, J. C.

2013-02-01

300

Improved zircon fission-track annealing model based on reevaluation of annealing data  

SciTech Connect

The thermal recovery (annealing) of mineral structure modified by the passage of fission fragments has long been studied by the etching technique. In minerals like apatite and zircon, the annealing kinetics are fairly well constrained from the hour to the million-year timescale and have been described by empirical and semi-empirical equations. On the other hand, laboratory experiments, in which ion beams interact with minerals and synthetic ceramics, have shown that there is a threshold temperature beyond which thermal recovery impedes ion-induced amorphization. In this work, it is assumed that this behavior can be extended to the annealing of fission tracks in minerals. It is proposed that there is a threshold temperature, T0, beyond which fission tracks are erased within a time t0, which is independent of the current state of lattice deformation. This implies that iso-annealing curves should converge to a fanning point in the Arrhenius pseudo-space (ln t vs. 1/T). Based on the proposed hypothesis, and laboratory and geological data, annealing equations are reevaluated. The geological timescale estimations of a model arising from this study are discussed through the calculation of partial annealing zone and closure temperature, and comparison with geological sample constraints found in literature. It is shown that the predictions given by this model are closer to field data on closure temperature and partial annealing zone than predictions given by previous models.

Guedes, Sandro [Instituto de Fisica Gleb Wataghin, Unicamp, Brazil; Moreira, Pedro A.F.P. [Universidade Estadual de Campinas, Sao Paulo; Devanathan, Ram [Pacific Northwest National Laboratory (PNNL); Weber, William J [ORNL; Hadler, Julio C [Instituto de Fisica Gleb Wataghin, Unicamp, Brazil

2013-01-01

301

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

302

Transfer-free graphene synthesis on insulating substrates via agglomeration phenomena of catalytic nickel films  

NASA Astrophysics Data System (ADS)

Graphene layers were synthesized by annealing amorphous carbon (a-C) thin films on Ni/SiO2/Si(111) substrates grown using pulse arc plasma deposition. Although the graphene layers were formed by catalytic reaction between a-C films and Ni metals, they were observed to be directly on the insulating SiO2/Si substrates with island-shaped metallic particles. These particles presumably resulted from agglomeration phenomena of thin Ni films at a high temperature. We speculated that the agglomeration phenomena allowed the graphene formation on SiO2/Si substrates. It was also confirmed that the particle size and graphene layer thickness depend on the starting Ni thickness.

Banno, Kazuya; Mizuno, Masaya; Fujita, Kazuhisa; Kubo, Toshiharu; Miyoshi, Makoto; Egawa, Takashi; Soga, Tetsuo

2013-08-01

303

Mathematics needed for Introduction to Transport Phenomena  

NSDL National Science Digital Library

A collection of math problems based on skills needed to successfully complete homework problems in an introductory course in Transport Phenomena. These problems do not introduce any new material for those who have taken Freshman Calculus classes and a sophomore level Differential Equations class. At Purdue University in the required Transport Phenomena course for MSE undergrads (MSE 340), I give a problem set like this the first day of classes in order to make clear the level of mathematical skill needed for the rest of the semester. I have found that it reduces difficulties with math later in the semester, allowing the students to focus on the transport phenomena.

Krane, Matthew J.

2007-10-12

304

Synchronization Phenomena and Epoch Filter of Electroencephalogram  

NASA Astrophysics Data System (ADS)

Nonlinear electrophysiological synchronization phenomena in the brain, such as event-related (de)synchronization, long distance synchronization, and phase-reset, have received much attention in neuroscience over the last decade. These phenomena contain more electrical than physiological keywords and actually require electrical techniques to capture with electroencephalography (EEG). For instance, epoch filters, which have just recently been proposed, allow us to investigate such phenomena. Moreover, epoch filters are still developing and would hopefully generate a new paradigm in neuroscience from an electrical engineering viewpoint. Consequently, electrical engineers could be interested in EEG once again or from now on.

Matani, Ayumu

305

Thermal annealing: a facile way of conferring responsivity to inert alkyl-chain-passivated nanoparticle arrays.  

PubMed

This work demonstrates a facile post-treatment strategy, vacuum thermal annealing, to fabricate a dodecanethiol-passivated gold nanoparticle (Au NP) array with organic solvent sensitivity. Through investigating the structure change of the Au NP array, it was found that the interparticle distance decreased during vacuum heat treatment, which meant a closer arrangement of the particles and a more dense packing of the dodecanethiol ligands in the interparticle region. The condensation would increase the interaction of the alkyl chain and enhance their interdigitation. Furthermore, on the basis of the stretching of the alkyl chains in organic solvents, the thermally treated Au NP array showed a good response to organic solvent or vapor by using the interdigitated dodecanethiol network as its responsive unit. The alkyl chains stretch to different extents in different organic solvents, leading to differences in interparticle distance, which provided a distinct blue shift of maximum wavelength upon exposure to various organic solvents or vapors. All of these results indicated that thermal annealing was an efficient way to confer responsivity to inert Au NP arrays. Together with the cost-effectiveness of such NP arrays, this study has potential in the development of economical sensors for medical diagnostics, food safety screening, and environmental pollution monitoring. PMID:25313464

Zhou, Jun; Song, Guoshuai; Li, Yan; Song, Youxin; Chen, Bin; Zhang, Xuemin; Wang, Tieqiang; Fu, Yu; Li, Fei

2014-11-01

306

Hadrons in Vacuum and Matter  

Microsoft Academic Search

In the first part of this thesis, we investigate the correlators and form factors of hadrons in vacuum viewed as a dilute gas of instantons and antiinstantons. Relying heavily on approximate bosonization techniques in four dimensions, we construct an effective action for constituent quarks in interaction with mesons and glueballs. The effective action is then used to study various meson,

Mourad Kacir

1995-01-01

307

Vacuum-jacketed line spacer  

NASA Technical Reports Server (NTRS)

Device has three integral, equally spaced leaf springs. Springs separate outer vacuum jacket from fluid carrying line, yet minimize conductive heat leaks and liquid boiloff. One-piece heat spring has sufficient flexibility to accommodate differential thermal expansion of inner and outer line.

Houte, F. A.; Mckee, H. B.; Patten, T. C.

1976-01-01

308

Switching in High Vacuum Enviroment  

Microsoft Academic Search

An analysis is made of the properties and problems of Maximum current interrupting ability and photos of contacts contacts, switching, and holding off high and low voltages, high which are interrupting up to 18,000 a are shown. and low currents ac, dc, and RF in a high vacuum environment with some relation to outer space problems. Characteristics of contacts from

H. Ross

1963-01-01

309

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

310

A vacuum ultraviolet spectrophotometric system  

NASA Technical Reports Server (NTRS)

The development of a vacuum ultraviolet spectrophotometric system for measuring transmittance and reflectance at variable angles is presented. Using various detectors and sources, the spectrophotometric system has been used for wavelengths from 80 nm to 300 nm with optical components up to 80 mm in diameter. The capability exists to make measurements through the visible range.

Spann, James F.; Keffer, Charles E.; Zukic, Muamer

1993-01-01

311

Chapter 13. The Vacuum System  

E-print Network

The vacuum chamber sectors are a welded fabrication of aluminum alloy 6061 plate. The standard chambers have the quadrupole feedthroughs, and for positioning of the internal support frame. There are 30 fixed NMR probes per primarily to provide rails for the NMR trolley cable car. The support frame is shown in Fig. 13

Brookhaven National Laboratory - Experiment 821

312

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

313

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

314

HIGH PRODUCTIVITY VACUUM BLASTING SYSTEM  

SciTech Connect

The objective of this project is to improve the productivity and lower the expense of existing vacuum blasting technology. This technology is used to remove radioactive contamination, PCBs, and lead-based paint and provides worker protection by continuously recycling the material and dust for the decontamination tasks. The proposed work would increase the cleaning rate and provide safe and cost-effective decontamination of the DOE sites. This work focuses on redesigning and improving existing vacuum blasting technology including blast head nozzles, ergonomic handling of the blast head by reducing its weight; brush-ring design, vacuum level regulator, efficiency of the dust separator, and operational control sensors. The redesign is expected to enhance the productivity and economy of the vacuum blasting system by at least 50% over current vacuum blasting systems. There are three phases in the project. Phase I consists of developing and testing mathematical models. Phase II consists of pre-prototype design and fabrication and pre-prototype unit testing. Phase III consists of prototype design and field verification testing. In phase I, mathematical models are developed and analyzed for the nozzle, blast head, wind curtain, and dust separator, first as individual devices and then combined as an integrated model. This allows study of respective airflow and design parameters. The Contractor shall, based on the results of the mathematical modeling studies, design experimental models of the components and test these models. In addition, the Contractor shall develop sensors to detect the relationship of the blast head to the blast surfaces and controls to minimize the dependency on an operator's skill and judgment to obtain optimum positioning, as well as real-time characterization sensors to determine as the blast head is moving the depth to which coatings must be removed, thereby improving production and minimizing waste. In phase II, the Contractor shall design and construct a pre-prototype of the nozzle, blast head with wind curtain, sensors, and dust separator and test this system to assess the performance of the new design under controlled conditions at the contractor's facility. In phase III, the Contractor shall design and construct a prototype of the High Productivity Vacuum Blasting System, based on the results of the pre-prototype design and testing performed. This unit will be a full-scale prototype and will be tested at a designated Department of Energy (DOE) facility. Based on the results, the system performance, the productivity, and the economy of the improved vacuum blasting system will be evaluated.

William S. McPhee

1999-05-31

315

Cold-Cathodes for Sensors and Vacuum Microelectronics  

SciTech Connect

The aim of this laboratory-directed research and development project was to study amorphous carbon (a-C) thin films for eventual cold-cathode electron emitter applications. The development of robust, cold-cathode emitters are likely to have significant implications for modern technology and possibly launch a new industry: vacuum micro-electronics (VME). The potential impact of VME on Sandia`s National Security missions, such as defense against military threats and economic challenges, is profound. VME enables new microsensors and intrinsically radiation-hard electronics compatible with MOSFET and IMEM technologies. Furthermore, VME is expected to result in a breakthrough technology for the development of high-visibility, low-power flat-panel displays. This work covers four important research areas. First, the authors studied the nature of the C-C bonding structures within these a-C thin films. Second, they determined the changes in the film structures resulting from thermal annealing to simulate the effects of device processing on a-C properties. Third, they performed detailed electrical transport measurements as a function of annealing temperature to correlate changes in transport properties with structural changes and to propose a model for transport in these a-C materials with implications on the nature of electron emission. Finally, they used scanning atom probes to determine important aspects on the nature of emission in a-C.

Siegal, M.P.; Sullivan, J.P.; Tallant, D.R.; Simpson, R.L. [Sandia National Labs., Albuquerque, NM (United States); DiNardo, N.J.; Mercer, T.W. [Drexel Univ., Philadelphia, PA (United States). Dept. of Physics and Astronomy; Martinez-Miranda, L.J. [Univ. of Maryland, College Park, MD (United States). Dept. of Materials Science and Engineering

1998-05-01

316

Construction Scheduling Optimization by Simulated Annealing  

Microsoft Academic Search

The process of generating optimized schedules for construction projects is a very time-consuming. For each construction task several execution restrictions, conditions and requirements such as technological dependencies or resource availabilities have to be considered. This leads to a multitude of possible execution orders and consequently to a hard optimization problem. Within this paper the integration of a flexible Simulated Annealing

M. König

2009-01-01

317

Annealed and quenched inhomogeneous cellular automata (INCA)  

Microsoft Academic Search

A probabilistic one-dimensional cellular automaton model by Domany and Kinzel is mapped into an inhomogeneous cellular automaton with the Boolean functions XOR and AND as transition rules. Wolfram's classification is recovered by varying the frequency of these two simple rules and by quenching or annealing the inhomogeneity. In particular, “class 4” is related to critical behavior in directed percolation. Also,

G. Y. Vichniac; P. Tamayo; H. Hartman

1986-01-01

318

Annealing and Mechanical Properties of ECAP Tantalum.  

National Technical Information Service (NTIS)

Equal Channel Angular Pressing (ECAP) was used to breakdown the microstructure of tantalum rods produced by Cabot and H.C. Starck. Hardness measurements from annealing samples showed a 100 degree C to 150 degree C difference in the softening response to r...

J. House, M. Nixon, P. Flater, R. De Angelis, R. Harris

2011-01-01

319

Laser annealing of cadmium sulfide crystals  

Microsoft Academic Search

Cadmium sulfide crystals with a disturbed surface layer about 5 ? thick were annealed by KrF* laser pulses of 10 nsec duration. This improved the crystal structure when the cadmium side was irradiated. The effect was not detectable on the sulfur side. The threshold energy density of the effect was ?0.25 J\\/cm2.

I V Vasilishcheva; V M Zubkov; R M Savvina; G G Skrotskaya; N F Starodubtsev; O N Talenski?; V N Poluboyarov; V A Trufan

1983-01-01

320

Stochastic assembly line balancing using simulated annealing  

Microsoft Academic Search

The problem of balancing assembly lines with stochastic task processing times is addressed. The size of the problems that can be solved by optimal methods is limited and hence many heuristics have been developed, which give sub-optimal solutions. An approach for solving the problem using the simulated annealing technique is presented here. The proposed approach tries to reach the global

G. SURESH; S. SAHU

1994-01-01

321

Laser annealing of nanocrystalline gold nanowires.  

PubMed

The efficacy of laser annealing for the thermal annealing of nanocrystalline gold nanowires is evaluated. Continuous laser illumination at 532 nm, focused to a 0.5 ?m diameter spot, was rastered perpendicular to the axis of nanocrystalline gold nanowire at ?2 kHz. This rastered beam was then scanned down the nanowire at velocities from 7 to 112 nm/s. The influence on the electrical resistance of the gold nanowire of laser power, polarization, translation speed, and nanowire width were evaluated. Nanocrystalline gold nanowires were prepared on glass surfaces using the lithographically patterned nanowire electrodeposition (LPNE) method. These nanowires had a rectangular cross section with a height of 20 (± 3) nm and widths ranging from 76 to 274 nm. The 4-contact electrical resistance of the nanowire is measured in situ during laser annealing and a real-time decrease in electrical resistance of between 30 and 65% is observed, depending upon the laser power and scan rate along the nanowire. These resistance decreases are associated with an increase in the mean grain diameter within these nanowires, measured using transmission electron microscopy, of up to 300%. The observed decrease in the electrical resistance induced by laser annealing conforms to classical predictions based upon the reduction in grain boundary scattering induced by grain growth. PMID:23855873

Kim, Jungyun; Lin, Chia-Yu; Xing, Wendong; Mecartney, Martha L; Potma, Eric O; Penner, Reginald M

2013-08-14

322

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

323

A technique for creating new visual phenomena  

E-print Network

This paper outlines a technique for creating new visual phenomena by proposing a systematic method of using existing media in novel manners. The technique involve s the random and purposeful manipulation of person-media ...

Ritter, Donald

1988-01-01

324

Classifying prion and prion-like phenomena.  

PubMed

The universe of prion and prion-like phenomena has expanded significantly in the past several years. Here, we overview the challenges in classifying this data informatically, given that terms such as "prion-like", "prion-related" or "prion-forming" do not have a stable meaning in the scientific literature. We examine the spectrum of proteins that have been described in the literature as forming prions, and discuss how "prion" can have a range of meaning, with a strict definition being for demonstration of infection with in vitro-derived recombinant prions. We suggest that although prion/prion-like phenomena can largely be apportioned into a small number of broad groups dependent on the type of transmissibility evidence for them, as new phenomena are discovered in the coming years, a detailed ontological approach might be necessary that allows for subtle definition of different "flavors" of prion / prion-like phenomena. PMID:24549098

Harbi, Djamel; Harrison, Paul M

2014-01-01

325

Ambroise August Liébeault and psychic phenomena.  

PubMed

Some nineteenth-century hypnosis researchers did not limit their interest to the study of the conventional psychological and behavioral aspects of hypnosis, but also studied and wrote about psychic phenomena such as mental suggestion and clairvoyance. One example, and the topic of this paper, was French physician Ambroise August Liébeault (1823-1904), who influenced the Nancy school of hypnosis. Liébeault wrote about mental suggestion, clairvoyance, mediumship, and even so-called poltergeists. Some of his writings provide conventional explanations of the phenomena. Still of interest today, Liébeault's writings about psychic phenomena illustrate the overlap that existed during the nineteenth-century between hypnosis and psychic phenomena--an overlap related to the potentials of the mind and its subconscious activity. PMID:19862897

Alvarado, Carlos S

2009-10-01

326

Fractal Geometry and Spatial Phenomena A Bibliography  

E-print Network

Fractal Geometry and Spatial Phenomena A Bibliography January 1991 Mark MacLennan, A. Stewart. MEASUREMENT ISSUES........................................................... 8 II.1 ESTIMATION OF FRACTAL DIMENSION - GENERAL ISSUES .......... 8 II.2 ESTIMATION OF FRACTAL DIMENSION FOR CURVES/PROFILES ... 9 II.3

California at Santa Barbara, University of

327

Processing of silicon solar cells by ion implantation and laser annealing  

NASA Technical Reports Server (NTRS)

Methods to improve the radiation tolerance of silicon cells for spacecraft use are described. The major emphasis of the program was to reduce the process-induced carbon and oxygen impurities in the junction and base regions of the solar cell, and to measure the effect of reduced impurity levels on the radiation tolerance of cells. Substrates of 0.1, 1.0 and 10.0 ohm-cm float-zone material were used as starting material in the process sequence. High-dose, low-energy ion implantation was used to form the junction in n+p structures. Implant annealing was performed by conventional furnace techniques and by pulsed laser and pulsed electron beam annealing. Cells were tested for radiation tolerance at Spire and NASA-LeRC. After irradiation by 1 MeV electrons to a fluence of 10 to the 16th power per sq cm, the cells tested at Spire showed no significant process induced variations in radiation tolerance. However, for cells tested at Lewis to a fluence of 10 to the 15th power per sq cm, ion-implanted cells annealed in vacuum by pulsed electron beam consistently showed the best radiation tolerance for all cell resistivities.

Minnucci, J. A.; Matthei, K. W.; Greenwald, A. C.

1981-01-01

328

Effect of annealing on Ni/GaN(0 0 0 1) contact morphology  

NASA Astrophysics Data System (ADS)

Morphology of Ni/GaN contact formed at room temperature (RT) by Ni vapor deposition onto the (0 0 0 1)-oriented n-type GaN surface under ultrahigh vacuum, and morphological changes introduced by annealing were studied. Measurements were carried out in situ using XPS, UPS, LEED and STM. The WF of the Ni film of the mean thickness 1 nm equaled 4.1 eV. For thicker layers (?2 nm), it increased to 5.1 eV. The Schottky barrier height of the Ni/GaN(0 0 0 1) contact formed at RT amounted to 1.20 eV. Annealing of the Ni/GaN contact at 650 °C resulted in Ga diffusion into the Ni film and Ni-Ga alloying. The dominating alloy phase was Ni3Ga. The alloying was accompanied by coalescence of Ni film grains into 3D islands of a Ni-Ga alloy. Annealing at 800 °C enriched the islands with Ga. The Ga-rich phases of NiGa and/or Ni3Ga2 were dominant in the alloy.

Grodzicki, M.; Mazur, P.; Zuber, S.; Pers, J.; Brona, J.; Ciszewski, A.

2014-06-01

329

Formation of thermal evaporated Ge Nano-Islands by high temperature annealing  

NASA Astrophysics Data System (ADS)

High Vacuum thermal evaporation was used to grow germanium islands on the silicon substrate covered by silicon oxide. The Ge nano-islands were formed by thermal annealing at different temperatures from 500 °C to 700 °C. Formation of islands was studied by various analytical techniques. The thickness of Ge layer was determined by rutherford backscattering spectroscopy (RBS). Also, combined with channeling technique, the composition and probable contaminants during synthesis processes were investigated. To explore the islands size and shape, both atomic force microscopy (AFM) and field emission scanning electron microscopy (FESEM) were used. Then the topographical images of surfaces were studied by AFM. The outcome of experimental evaluations of growth mechanism has indicated that with increasing the annealing temperature up to 700 °C, Ge islands were appeared from a uniform layer. Moreover, the statistical assessments of surfaces have shown that the nano-island's sizes can be varied from several hundred nanometers to 30 nm by growing the annealing temperature. The reduction of the size along with an increase of the number of nano-islands after each thermal treatment is a major factor to prohibit us from seeing their clear images in AFM. The possibility of running statistical estimation on islands, instead, is the powerful tool of extracting and probing the distribution and the shape of Ge island's peak in AFM images.

Lotfi, E.; Ghaderi, A.; Solaymani, S.; Arghavani Nia, B.; Baghizadeh, A.; Agha-Aligol, D.; Hantehzadeh, M. R.; Hodaei, A.

2012-08-01

330

A Multiagent Approach to Modelling Complex Phenomena  

Microsoft Academic Search

Designing models of complex phenomena is a difficult task in engineering that can be tackled by composing a number of partial\\u000a models to produce a global model of the phenomena. We propose to embed the partial models in software agents and to implement\\u000a their composition as a cooperative negotiation between the agents. The resulting multiagent system provides a global model

Francesco Amigoni; Viola Schiaffonati

2008-01-01

331

Reproductive phenomena of a sexual buffelgrass plant  

E-print Network

lines apomictic lines. 21 22 REPRODUCTIVE PHENOMENA OF A SEXUAL BUFFELGRASS PLANT INTRODUCTION Buffelgrass, Pennisetum ciliare (L. ) Link, is a polymorphic, perennial, warm-season, bunch grass with a native range extending from Africa to India... lines apomictic lines. 21 22 REPRODUCTIVE PHENOMENA OF A SEXUAL BUFFELGRASS PLANT INTRODUCTION Buffelgrass, Pennisetum ciliare (L. ) Link, is a polymorphic, perennial, warm-season, bunch grass with a native range extending from Africa to India...

Taliaferro, Charles Millard

2012-06-07

332

Clustering and other exotic phenomena in nuclei  

Microsoft Academic Search

.   Nuclei feature a rich variety of many-body phenomena. Especially the clustering of nucleons, which leads to molecule like\\u000a structures, and halos formed by weakly bound nucleons are regarded as exotic phenomena that standard many-body methods like\\u000a the shell\\u000a model have difficulties to describe. On the other hand cluster models that build in such structures explicitly use very simplistic\\u000a effective

T. Neff; H. Feldmeier

2008-01-01

333

An Econophysics Model for the Migration Phenomena  

E-print Network

Knowing and modelling the migration phenomena and especially the social and economic consequences have a theoretical and practical importance, being related to their consequences for development, economic progress (or as appropriate, regression), environmental influences etc. One of the causes of migration, especially of the interregional and why not intercontinental, is that resources are unevenly distributed, and from the human perspective there are differences in culture, education, mentality, collective aspirations etc. This study proposes a new econophysics model for the migration phenomena.

Gheorghiu, Anca

2012-01-01

334

Materials for ultra-high vacuum  

SciTech Connect

This report discusses materials for use in ultrahigh vacuum systems of 1 {times} 10{sup {minus}9} Torr or lower. The author briefly discusses alloys, solders, insulators and joining methods for vacuum systems. (JDL)

Lee, G.

1989-08-15

335

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

336

Ion pump provides increased vacuum pumping speed  

NASA Technical Reports Server (NTRS)

Multiple-cell ion pumps with increased vacuum pumping speed are used for producing ultrahigh vacuums in vacuum tubes and mass spectrometers. The pump has eight cathode-anode magnetron cells arranged in a cylinder which increase the surface area of the cathode.

1965-01-01

337

REVIEW ARTICLE Vacuum Rabi splitting in semiconductors  

E-print Network

of a nanocavity. This review describes the history of realizing vacuum Rabi splitting (VRS) in the single-QD (SQDREVIEW 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

Loss, Daniel

338

Vacuum energy of CP(1) solitons  

E-print Network

The vacuum energy of two CP(1) solitons on a torus is computed numerically. A numerical technique for zeta-function regularisation is proposed to remove the divergences of the vacuum energy. After performing the numerical regularisation, we observe the effect of the vacuum energy on the two soliton interactions.

Ian G Moss; Noriko Shiiki; Takashi Torii

2001-03-22

339

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

340

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

341

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

342

Dark Energy From Vacuum Fluctuations  

E-print Network

We describe briefly a novel interpretation of the physical nature of dark energy (DE), based on the vacuum fluctuations model by Gurzadyan & Xue, and describe an internally consistent solution for the behavor of DE as a function of redshift. A key choice is the nature of the upper bound used for the computation of energy density contributions by vacuum modes. We show that use of the comoving horizon radius produces a viable model, whereas use of the proper horizon radius is inconsistent with the observations. After introduction of a single phenomenological parameter, the model is consistent with all of the curently available data, and fits them as well as the standard cosmological constant model, while making testable predictions. While some substantial interpretative uncertainties remain, future developments of this model may lead to significant new insights into the physical nature of DE.

S. G. Djorgovski; V. G. Gurzadyan

2006-10-06

343

Bubbles created from vacuum fluctuation  

E-print Network

We show that the bubbles $S^2\\times S^2$can be created from vacuum fluctuation in certain De Sitter universe, so the space-time foam-like structure might really be constructed from bubbles of $S^2\\times S^2$ in the very early inflating phase of our universe. But whether such foam-like structure persisted during the later evolution of the universe is a problem unsolved now.

Liao Liu; Feng He

2001-01-05

344

Vacuum Energy as Spectral Geometry  

E-print Network

Quantum vacuum energy (Casimir energy) is reviewed for a mathematical audience as a topic in spectral theory. Then some one-dimensional systems are solved exactly, in terms of closed classical paths and periodic orbits. The relations among local spectral densities, energy densities, global eigenvalue densities, and total energies are demonstrated. This material provides background and motivation for the treatment of higher-dimensional systems (self-adjoint second-order partial differential operators) by semiclassical approximation and other methods.

Stephen A. Fulling

2007-06-19

345

Holographic description of vacuum bubbles  

E-print Network

We discuss a holographic description of vacuum bubbles, with possible implications for a consistent description of the multiverse. In particular, we elaborate on the recent observation by Maldacena, that the interior of AdS bubbles can be described in terms of CFT degrees of freedom living on the worldsheet of the bubble wall. We consider the scattering of bulk gravitons in the ambient parent vacuum, off the bubble wall. In the dual description, the transmission coefficient is interpreted as the probability that a graviton is absorbed by the worldsheet CFT degrees of freedom. The result is in agreement with intuitive expectations. Conformal invariance is not exact in this setup, and the leading corrections due to the IR and UV cut-offs are displayed. Aside from bulk scattering states, we find that when a bubble nucleates within a parent dS vacuum, there is a zero mode of the graviton which describes lower dimensional gravity with a finite Newton's constant. This massless graviton lives within one Hubble radius away from the bubble wall. Possible implications for a fully holographic description of the inflating multiverse are briefly discussed.

Jaume Garriga

2010-12-29

346

Cosmic vacuum and galaxy formation  

NASA Astrophysics Data System (ADS)

It is demonstrated that the protogalactic perturbations must enter the nonlinear regime before the red shift z? 1; otherwise they would be destroyed by the antigravity of the vacuum dark energy at the subsequent epoch of the vacuum domination. At the zrrV={M/[(8?/3)?V]}1/3, where M is the mass of a given over-density and ?V is the vacuum density. The criterion provides a new relation between the largest mass condensations and their spatial scales. All the real large-scale systems follow this relation definitely. It is also shown that a simple formula is possible for the key quantity in the theory of galaxy formation, namely the initial amplitude of the perturbation of the gravitational potential in the protogalactic structures. The amplitude is time independent and given in terms of the Friedmann integrals, which are genuine physical characteristics of the cosmic energies. The results suggest that there is a strong correspondence between the global design of the Universe as a whole and the cosmic structures of various masses and spatial scales.

Chernin, A. D.

2006-04-01

347

Holographic description of vacuum bubbles  

E-print Network

We discuss a holographic description of vacuum bubbles, with possible implications for a consistent description of the multiverse. In particular, we elaborate on the recent observation by Maldacena, that the interior of AdS bubbles can be described in terms of CFT degrees of freedom living on the worldsheet of the bubble wall. We consider the scattering of bulk gravitons in the ambient parent vacuum, off the bubble wall. In the dual description, the transmission coefficient is interpreted as the probability that a graviton is absorbed by the worldsheet CFT degrees of freedom. The result is in agreement with intuitive expectations. Conformal invariance is not exact in this setup, and the leading corrections due to the IR and UV cut-offs are displayed. Aside from bulk scattering states, we find that when a bubble nucleates within a parent dS vacuum, there is a zero mode of the graviton which describes lower dimensional gravity with a finite Newton's constant. This massless graviton lives within one Hubble radiu...

Garriga, Jaume

2010-01-01

348

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

349

Annealing and the Normalized N-Cut  

PubMed Central

We describe an annealing procedure that computes the normalized N-cut of a weighted graph G. The first phase transition computes the solution of the approximate normalized 2-cut problem, while the low temperature solution computes the normalized N-cut. The intermediate solutions provide a sequence of refinements of the 2-cut that can be used to split the data to K clusters with 2 ? K ? N. This approach only requires specification of the upper limit on the number of expected clusters N, since by controlling the annealing parameter we can obtain any number of clusters K with 2 ? K ? N. We test the algorithm on an image segmentation problem and apply it to a problem of clustering high dimensional data from the sensory system of a cricket. PMID:19190710

Gedeon, Tomáš; Parker, Albert E.; Campion, Collette; Aldworth, Zane

2007-01-01

350

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.

351

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

352

Evolution of strain and mechanical properties upon annealing in He-implanted 6H-SiC  

NASA Astrophysics Data System (ADS)

The effects of annealing temperature on strain and mechanical property changes of 6H-SiC implanted with helium ions at 600 K to doses of 3 × 1015 cm-2, 1 × 1016 cm-2 and 3 × 1016 cm-2 and at an ion energy of 100 keV were investigated by using high-resolution X-ray diffraction (XRD), nano-indentation and transmission electron microscopy (TEM). Strain increases with increasing displacements per atom (dpa). Strain relaxation in terms of changes in ?d/d exhibited a linear decrease with increasing annealing temperature ranging from 873 K to 1473 K for 30 min in vacuum. The relaxation activation energies of the strains were estimated by Arrhenius law to be in the range of 0.4-0.7 eV. Irradiation-induced hardening was observed via nano-indentation measurements as a function of annealing. The hardness of the highly damaged layer decreased monotonically with increasing annealing temperature for the samples implanted with He ions to doses of 3 × 1015 cm-2 and 1 × 1016 cm-2, and where no helium bubbles were formed in the damaged layer. The hardness of the damaged layer initially decreased and then increased with increasing annealing temperature from 600 K to 1073 K for the sample implanted He ions to a dose of 3 × 1016 cm-2, where numerous helium bubbles were formed in the damaged layer. The TEM results suggest that the growth of helium bubbles emits interstitials upon annealing. These interstitials agglomerate into stacking faults and dislocation loops, which increase the hardness.

Li, B. S.; Wang, Z. G.; Zhang, C. H.; Wei, K. F.; Yao, C. F.; Sun, J. R.; Cui, M. H.; Li, Y. F.; Zhu, H. P.; Du, Y. Y.; Zhu, Y. B.; Pang, L. L.; Song, P.; Wang, J.

2014-12-01

353

Compactified Vacuum in Ten Dimensions.  

NASA Astrophysics Data System (ADS)

Since the 1920's, theories which unify gravity with the other fundamental forces have called for more than the four observed dimensions of space-time. According to such a theory, the vacuum consists of flat four-dimensional space-time described by the Minkowski metric M ^4 and a "compactified" space B. The dimensions of B are small, and the space can only be observed at distance scales smaller than the present experimental limit. These theories have had serious difficulties. The equations of gravity severely restrict the possible choices for the space B. The allowed spaces are complicated and difficult to study. The vacuum is furthermore unstable in the sense that a small perturbation causes the compactified dimensions to expand indefinitely. There is an addition a semi-classical argument which implies that the compactified vacuum be annihilated by virtual black holes. It follows that a universe with compactified extra dimensions could not have survived to the present. These results were derived by applying the equations of general relativity to spaces of more than four dimensions. The form of these equations was assumed to be unchanged by an increase in the number of dimensions. Recently, it has been proposed that gravity in more than four dimensions may involve terms of higher order in the curvature as well as the linear terms present in ordinary general relativity. I illustrate the effect of such terms by considering the example B = S^6 where S ^6 is the six-dimensional sphere. Only when the extra terms are included is this choice of the compactified space allowed. I explore the effect of a small perturbation on such a vacuum. The ten-dimensional spherically symmetric potential is examined, and I determine conditions under which the formation of virtual black holes is forbidden. The example M^4 times S^6 is still plagued by the semi -classical instability, but this result does not hold in general. The requirement that virtual black holes be forbidden provides a test for any theory which predicts a compactified vacuum.

Wurmser, Daniel

1987-09-01

354

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

355

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

356

The making of extraordinary psychological phenomena.  

PubMed

This article considers the extraordinary phenomena that have been central to unorthodox areas of psychological knowledge. It shows how even the agreed facts relating to mesmerism, spiritualism, psychical research, and parapsychology have been framed as evidence both for and against the reality of the phenomena. It argues that these disputes can be seen as a means through which beliefs have been formulated and maintained in the face of potentially challenging evidence. It also shows how these disputes appealed to different forms of expertise, and that both sides appealed to belief in various ways as part of the ongoing dispute about both the facts and expertise. Finally, it shows how, when a formal Psychology of paranormal belief emerged in the twentieth century, it took two different forms, each reflecting one side of the ongoing dispute about the reality of the phenomena. PMID:25363382

Lamont, Peter

2012-01-01

357

Critical phenomena in gravitational collapse - Living Reviews  

E-print Network

As first discovered by Choptuik, the black hole threshold in the space of initial data for general relativity shows both surprising structure and surprising simplicity. Universality, power-law scaling of the black hole mass, and scale echoing have given rise to the term ``critical phenomena''. They are explained by the existence of exact solutions which are attractors within the black hole threshold, that is, attractors of codimension one in phase space, and which are typically self-similar. This review gives an introduction to the phenomena, tries to summarize the essential features of what is happening, and then presents extensions and applications of this basic scenario. Critical phenomena are of interest particularly for creating surprising structure from simple equations, and for the light they throw on cosmic censorship and the generic dynamics of general relativity.

C. Gundlach

2000-01-17

358

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

359

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

360

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

361

Modeling of the transient interstitial diffusion of implanted atoms during low-temperature annealing of silicon substrates  

E-print Network

It has been shown that many of the phenomena related to the formation of "tails" in the low-concentration region of ion-implanted impurity distribution are due to the anomalous diffusion of nonequilibrium impurity interstitials. These phenomena include boron implantation in preamorphized silicon, a "hot" implantation of indium ions, annealing of ion-implanted layers et cetera. In particular, to verify this microscopic mechanism, a simulation of boron redistribution during low-temperature annealing of ion-implanted layers has been carried out under different conditions of transient enhanced diffusion suppression. Due to the good agreement with the experimental data, the values of the average migration length of nonequilibrium impurity interstitials have been obtained. It has been shown that for boron implanted into a silicon layer preamorphized by germanium ions the average migration length of impurity interstitials at the annealing temperature of 800 Celsius degrees be reduced from 11 nm to approximately 6 nm due to additional implantation of nitrogen. The further shortening of the average migration length is observed if the processing temperature is reduced to 750 Celsius degrees. It is also found that for implantation of BF2 ions into silicon crystal, the value of the average migration length of boron interstitials is equal to 7.2 nm for thermal treatment at a temperature of 800 Celsius degrees.

O. I. Velichko; A. P. Kavaliova

2011-08-21

362

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

363

Effects of a modular two-step ozone-water and annealing process on silicon carbide graphene  

NASA Astrophysics Data System (ADS)

By combining ozone and water, the effect of exposing epitaxial graphene on silicon carbide to an aggressive wet-chemical process has been evaluated after high temperature annealing in ultra high vacuum. The decomposition of ozone in water produces a number of oxidizing species, however, despite long exposure times to the aqueous-ozone environment, no graphene oxide was observed after the two-step process. The systems were comprehensively characterized before and after processing using Raman spectroscopy, core level photoemission spectroscopy, and angle resolved photoemission spectroscopy together with low energy electron diffraction, low energy electron microscopy, and atomic force microscopy. In spite of the chemical potential of the aqueous-ozone reaction environment, the graphene domains were largely unaffected raising the prospect of employing such simple chemical and annealing protocols to clean or prepare epitaxial graphene surfaces.

Webb, Matthew J.; Polley, Craig; Dirscherl, Kai; Burwell, Gregory; Palmgren, Pâl; Niu, Yuran; Lundstedt, Anna; Zakharov, Alexei A.; Guy, Owen J.; Balasubramanian, Thiagarajan; Yakimova, Rositsa; Grennberg, Helena

2014-08-01

364

Effect of post-growth annealing on the optical properties of LiGaS2 nonlinear crystals  

NASA Astrophysics Data System (ADS)

High chalcogen volatility and Li interaction with the container walls result in variation of crystal composition and presence of both extended and point defects in as-grown LiGaS2 nonlinear crystals. Annealing in appropriate conditions is used to correct the composition and improve the optical quality. We annealed LiGaS2 in vacuum, in the presence of Li2S, Ga2S3, and S, and studied changes in transmission, photoluminescence and photo-induced absorption. OH groups, S-H and S-S complexes, sulfur vacancies and cation antisite defects (GaLi) are most important. Photo-induced absorption is reversible: It appears after illumination with UV/blue light and disappears after illumination with IR light or by heating the sample.

Yelisseyev, Alexander; Starikova, Marina; Isaenko, Ludmila; Lobanov, Sergei; Petrov, Valentin

2011-03-01

365

Annealing effects on the microstructure and coercive field of two ferritic-martensitic Eurofer steels: A comparative study  

NASA Astrophysics Data System (ADS)

Reduced-activation ferritic-martensitic steels are promising candidates for structural applications in future nuclear fusion power plants. Oxide dispersion strengthened ODS-Eurofer and Eurofer 97 steels were cold rolled to 80% reduction in thickness and annealed in vacuum for 1 h from 200 to 1350 °C to evaluate both their thermal stability and magnetic behavior. The microstructural changes were followed by magnetic measurements, in particular the corresponding variation of the coercive field (Hc), as a function of both annealing and tempering treatments. Results show that Y2O3 nanoparticles strongly affect the mechanical properties of ODS-Eurofer steel but leave their magnetic properties fairly unchanged when compared with Eurofer-97 steel.

Oliveira, V. B.; Sandim, M. J. R.; Stamopoulos, D.; Renzetti, R. A.; Santos, A. D.; Sandim, H. R. Z.

2013-04-01

366

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

367

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

368

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

369

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

370

Leak Detection in Vacuum Technology  

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. This module explains the importance of determining vacuum system integrity through leak qualification tests. Learners are introduced to a systematic set of methods for determining the existence of a leak, as well as its size, type and location. Emphasis is placed on the use of a helium mass spectrometer leak detector (MSLD). The centerpiece of this module is a computer program that simulates leak detection with an MSLD.

2012-12-26

371

Vacuum energy and relativistic invariance  

E-print Network

It is argued that the zero-point energies of free quantum fields diverge at most quadratically and not quartically, as is generally believed. This is a consequence of the relativistic invariance which requires that the energy density of the vacuum $\\rho$ and its pressure $p$ satisfy $\\rho=-p$. The usually obtained quartic divergence is an artifact of the use of a noninvariant regularization which violates this relation. One consequence of our results is that the zero-point energies of free massless fields vanish. Implications for the cosmological constant problem are briefly discussed.

E. Kh. Akhmedov

2002-04-04

372

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

2013-10-22

373

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

374

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

375

Enhancing the photocatalytic efficiency of sprayed ZnO thin films through double doping (Sn + F) and annealing under different ambiences  

NASA Astrophysics Data System (ADS)

Doubly (Sn + F) doped zinc oxide (ZnO:Sn:F) thin films were deposited onto glass substrates using a simplified spray pyrolysis technique. The deposited films were annealed at 400 °C under two different ambiences (air and vacuum) for 2 h. The photocatalytic activity of these films was assessed through photocatalytic decolorization kinetics of Methylene Blue (MB) dye and the decolorization efficiency of the annealed films was compared with that of their as-deposited counterpart. The photocatalytic studies reveal that the ZnO:Sn:F films annealed under vacuum environment exhibits better photocatalytic efficiency when compared with both air annealed and as-deposited films. The SEM and TEM images depict that the surface of each of the films has an overlayer comprising of nanobars formed on a bottom layer, having spherical grains. The studies show that the diameter of the nanobars plays crucial role in enhancing the photocatalytic activity of the ZnO:Sn:F films. The structural, optical and electrical studies substantiate the discussions on the photocatalytic ability of the deposited films.

Ravichandran, K.; Mohan, R.; Sakthivel, B.; Varadharajaperumal, S.; Devendran, P.; Alagesan, T.; Pandian, K.

2014-12-01

376

Possible new wave phenomena in the brain  

E-print Network

We propose to search for new wave phenomena in the brain by using interference effects in analogy to the well-known double slit (Young) experiment. This method is able to extend the range of oscillation frequencies to much higher values than currently accessible. It is argued that such experiments may test the hypothesis of the wave nature of information coding.

Jerzy Szwed

2009-06-15

377

Prediction of dynamic phenomena in massed explosions  

Microsoft Academic Search

bumps. Based on the nature of shock bumps and the nature of their occurrence, the method devised for predicting dynamic phenomena includes the following: an analysis of the geological, mine-engineering, and geomechanical situation at the deposit; the identification of dynamically active geological structures; determination of the volume of the excavated space and goal; evaluation of the seismic energy of the

M. V. Kurlenya; A. Ao Eremenko; S. P. Usol'tsev; N. I. Sklyar; V. A. Eremenko

1996-01-01

378

Wave Phenomena in an Acoustic Resonant Chamber  

ERIC Educational Resources Information Center

Discusses the design and operation of a high Q acoustical resonant chamber which can be used to demonstrate wave phenomena such as three-dimensional normal modes, Q values, densities of states, changes in the speed of sound, Fourier decomposition, damped harmonic oscillations, sound-absorbing properties, and perturbation and scattering problems.…

Smith, Mary E.; And Others

1974-01-01

379

Conference on Transport Phenomena with Moving Boundaries  

E-print Network

Conference on Transport Phenomena with Moving Boundaries 9th -10th October, Berlin, Germany VOF-of-Fluid (VOF) method. For the examination of mass transfer, single bubbles are held in counter require numerical methods that resolve the free phase boundary. Based on the VOF-method, mass transfer

Bothe, Dieter

380

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

381

Atmospheric phenomena before and during sunset  

NASA Astrophysics Data System (ADS)

The atmospheric transmittance and the astronomical refraction for low-elevation trajectories are discussed and quantitatively developed. The results are used to describe and calculate some of the fascinating atmospheric phenomena occurring shortly before and during sunset, such as the diminishing apparent luminance of the sun, its shape during sunset, and the green flash.

Menat, M.

382

Observations of Nonlinear Phenomena in Rotordynamics  

Microsoft Academic Search

Observations, analysis and understanding of nonlinear rotordynamic phenomena observed in aircraft gas turbine engines and other high-speed rotating machinery over the course of the author's career are described. Included are observations of sum-and-difference frequency response; effects of roller bearing clearance; relaxation oscillations; subharmonic response; chaotic response; and other generic nonlinear responses such as superharmonic and ultra-subharmonic response.

Fredric F. Ehrich

2008-01-01

383

Cooperative phenomena in strongly correlated electron systems  

Microsoft Academic Search

In this review we present results of our theoretical study of cooperative phenomena in strongly correlated electron systems obtained within various generalizations of the Falicov-Kimball model. The primary goal of this study was to identify crucial interactions that lead to the stabilization of the specific cooperative phenomenon, and then try to elaborate its comprehensive microscopic description. The main attention is

Pavol Farkasovský

2010-01-01

384

Analysis Of Plunging Phenomena In Water Reservoirs  

Microsoft Academic Search

Two analyses of plunging phenomena in reservoirs are presented, one based upon a simple energy conserving flow and the other upon a gradually varied two-layer system. The various types of interfacial profiles are described and the depth at the plunge point is determined. The predicted plunge depth agrees reasonably well with the laboratory measurements of SINGH and SHAH (1971).

S. B. Savage; J. Brimberg

1975-01-01

385

Critical phenomena in globally coupled excitable elements  

NASA Astrophysics Data System (ADS)

Critical phenomena in globally coupled excitable elements are studied by focusing on a saddle-node bifurcation at the collective level. Critical exponents that characterize divergent fluctuations of interspike intervals near the bifurcation are calculated theoretically. The calculated values appear to be in good agreement with those determined by numerical experiments. The relevance of our results to jamming transitions is also mentioned.

Ohta, Hiroki; Sasa, Shin-Ichi

2008-12-01

386

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...

387

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.

388

Corruption, fraud and cybercrime as dehumanizing phenomena  

Microsoft Academic Search

Purpose – The purpose of this paper is to describe corruption, fraud and cybercrime as dehumanizing phenomena. Design\\/methodology\\/approach – Berdiaeff's notion of slavery and Sartre's concepts of lie and bad faith are used in order to put light on the dehumanizing effects of corruption, fraud and cybercrime over social life itself. Findings – Corruption, fraud and cybercrime constitute dehumanizing processes

Michel Dion

2011-01-01

389

Corporate strategy and the Social Networking phenomena  

Microsoft Academic Search

The Social Networking (SN) phenomena has developed relatively overnight and is continuing to develop at an exponential pace. It allows for innovative new methods of disseminating and collecting information in ways never before dreamed possible by corporate executives. The rise of Social Networking is becoming a disruptive technology for traditional marketing and advertising medium such as radio, television, web page,

Robert L. Johnson

2010-01-01

390

Reduplication phenomena: body, mind and archetype.  

PubMed

The many biological and few psychodynamic explanations of reduplicative syndromes tend to have paralleled the dualism of the phenomenon with organic theories concentrating on form and dynamic theories emphasising content. This paper extends the contribution of psychoanalytic thinking to an elucidation of the form of the delusion. Literature on clinical and aetiological aspects of reduplicative phenomena is reviewed alongside a brief examination of psychoanalytic models not overtly related to these phenomena. The human experience of doubles as universal archetype is considered. There is an obvious aetiological role for brain lesions in delusional misidentifications, but psychological symptoms in an individual can rarely be reduced to an organic disorder. The splitting and doubling which occurs in the phenomena have resonances in cultural mythology and in theories from different schools of psychodynamic thought. For the individual patient and doctor, it is a diverting but potentially empty debate to endeavour to draw strict divisions between what is physical and what is psychological although both need to be investigated. Nevertheless, in patients in whom there is clear evidence of an organic contribution to aetiology a psychodynamic understanding may serve to illuminate the patient's experience. Organic brain disease or serious functional illness predispose to regression to earlier modes of archetypical and primitive thinking with concretization of the metaphorical and mythological world. Psychoanalytic models have a contribution in describing the form as well as the content of reduplicative phenomena. PMID:11003374

Garner, J

2000-09-01

391

Quark confinement and surface critical phenomena  

SciTech Connect

Surface critical phenomena and the related onset of Goldstone modes probe the fundamental properties of the confining flux in Quantum Chromodynamics. New ideas on surface roughening and their implications for lattice studies of quark confinement are presented. Problems with the oversimplified string description of the Wilson flux sheet are discussed.

K.J. Juge, J. Kuti and C.J. Morningstar

1999-10-20

392

Dream phenomena induced by chronic levodopa therapy  

Microsoft Academic Search

Summary Twenty-seven of eighty-eight (30.7%) Parkinsonian patients on chronic levodopa or levodopa\\/carbidopa therapy developed drug related dream phenomena. The patients reported three separate types of new dreams which we have classified as vivid dreams, night terrors and nightmares. These dreams are correlated to the duration of levodopa therapy although the mechanism of their production is unclear.

B. Sharf; Ch. Moskovitz; M. D. Lupton; H. L. Klawans

1978-01-01

393

Certain relativistic phenomena in crystal optics  

Microsoft Academic Search

Relativistic unsteady phenomena are established for a crystalline medium with unaligned sets of permittivity and permeability principal axes, but incorporating a compounded uniaxiality about some nonprincipal direction. All effects originate from a suddenly activated, arbitrarily oriented, maintained line current conducted with a finite velocity v. Integral representations studied in another paper (Chee-Seng) are applied. The original coordinate system is subjected

Lim Chee-Seng

1980-01-01

394

Jet flow phenomena during nucleate boiling  

Microsoft Academic Search

Boiling phenomena are with highly complex nonlinear and nonequilibrium characteristics, which cause diversity and complexity of boiling nucleation. In the present paper, an experimental investigation was conducted to investigate the nucleate boiling behavior on a very fine heating wire. Using zoom routine and CCD camera system, the dynamical process of nucleate boiling was visually observed and several modes of jet

H. Wang; X. F. Peng; B. X. Wang; D. J. Lee

2002-01-01

395

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

396

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

397

Ultrahigh vacuum surface analysis coupled with a high pressure system for the study of near critical and supercritical fluid processing  

SciTech Connect

A system has been constructed for ultrahigh vacuum analysis investigation of surfaces after high pressure fluid processing. The system features a cell capable of withstanding pressures up to 400 bar that opens directly into an ultrahigh vacuum (10{sup {minus}10} Torr) system to allow transfer of samples for analysis. Temperature control of the cell and fluid is possible to within {plus_minus}1{degree}C up to temperatures of 400{degree}C. The high pressure system design allows the preparation and study of supercritical fluid mixtures as well as of pure components. X-ray photoelectron spectroscopy, Auger electron spectroscopy, sputter etching, and vacuum anneal capabilities comprise the surface analysis system. The fluids investigated include supercritical carbon dioxide, methanol, water, and their mixtures; these are applied to processes such as surface cleaning and thin film etching using high pressure fluids. {copyright} {ital 1997 American Institute of Physics.}

Bakker, G.L.; Hess, D.W. [Department of Chemical Engineering, Lehigh University, Bethlehem, Pennsylvania 18015 (United States)] [Department of Chemical Engineering, Lehigh University, Bethlehem, Pennsylvania 18015 (United States)

1997-01-01

398

Crystal Melting and Wall Crossing Phenomena  

E-print Network

This paper summarizes recent developments in the theory of Bogomol'nyi-Prasad-Sommerfield (BPS) state counting and the wall crossing phenomena, emphasizing in particular the role of the statistical mechanical model of crystal melting. This paper is divided into two parts, which are closely related to each other. In the first part, we discuss the statistical mechanical model of crystal melting counting BPS states. Each of the BPS state contributing to the BPS index is in one-to-one correspondence with a configuration of a molten crystal, and the statistical partition function of the melting crystal gives the BPS partition function. We also show that smooth geometry of the Calabi-Yau manifold emerges in the thermodynamic limit of the crystal. This suggests a remarkable interpretation that an atom in the crystal is a discretization of the classical geometry, giving an important clue as to the geometry at the Planck scale.In the second part we discuss the wall crossing phenomena. Wall crossing phenomena states that the BPS index depends on the value of the moduli of the Calabi-Yau manifold, and jumps along real codimension one subspaces in the moduli space. We show that by using type IIA/M-theory duality, we can provide a simple and an intuitive derivation of the wall crossing phenomena, furthermore clarifying the connection with the topological string theory. This derivation is consistent with another derivation from the wall crossing formula, motivated by multi-centered BPS extremal black holes. We also explain the representation of the wall crossing phenomena in terms of crystal melting, and the generalization of the counting problem and the wall crossing to the open BPS invariants.

Masahito Yamazaki

2010-02-09

399

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

400

Vacuum silicon photomultipliers: Recent developments  

NASA Astrophysics Data System (ADS)

VSiPMT (Vacuum Silicon PhotoMultiplier Tube) is an innovative design for a modern hybrid, high gain, silicon based photodetector based on the combination of a SiPM with a hemispherical vacuum glass PMT standard envelope. In such a device photoelectrons emitted by the photocathode are accelerated and focused by an electric field towards a small focal area covered by the SiPM which therefore acts as an amplifier, thus substituting the classical dynode chain of a PMT. With a view to the realization of a first prototype of VSiPMT our group is carrying out a preliminary work aimed at the study of SiPM performances as an electron detector, including an accurate Geant4-based simulation of the interaction between SiPM and electron beams. In order to perform a full characterization of the SiPM we developed an experimental setup for the extraction and the acceleration of a beam of backward secondary electrons emitted after the bombardment of a carbon foil by a proton beam extracted in a TTT-3 accelerator.

Barbarino, Giancarlo; Barbato, Felicia Carla Tiziana; Campajola, Luigi; de Asmundis, Riccardo; De Rosa, Gianfranca; Mollo, Carlos Maximiliano; Vivolo, Daniele

2013-08-01

401

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

402

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

403

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.

Albareti, F D; Maroto, A L

2014-01-01

404

Development of the Vacuum Comparison Standard Device  

NASA Astrophysics Data System (ADS)

The standard device of vacuum comparison is built compared the dynamic method, the static compared method and the static expansion method, this device combined three methods are to meet the wide range of calibrating vacuum gauge. It is used to calibrate 1×105?5×10-4 Pa within the scope of various types of vacuum gauge. The characteristic of this equipment is a simple in structure, easy to operate, high efficiency, practicability of the vacuum standard. Especially suitable for a large number of routine calibrations, the device consists of turbo-molecular pump, calibration container, the standard vacuum gauge and metal expansion valves and other components, and its main technical specifications in line with the International Standards Organization (ISO) and the domestic vacuum standards.

Shufeng, Zhang; Ruihai, Song; Ming, Gao; Huan, Wang; Junwei, Jia; Hulin, Tian

405

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

406

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

407

Electromagnetic Fields in the QCD Vacuum  

E-print Network

Quarks play an active role in shaping the QCD vacuum structure. Being dual carriers of both `color' and `electric' charges they also respond to externally applied electromagnetic fields. Thus, in principle, the vacuum of strong interactions influences higher order QED processes such as photon-photon scattering. We survey here the current status of the understanding of the vacuum structure of strong interactions, and take a fresh look at its electromagnetic properties.

Johann Rafelski; H. -Thomas Elze

1998-06-16

408

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

409

Higher-order scalar interactions and SM vacuum stability  

E-print Network

Investigation of the structure of the Standard Model effective potential at very large field strengths opens a window towards new phenomena and can reveal properties of the UV completion of the SM. The map of the lifetimes of the vacua of the SM enhanced by nonrenormalizable scalar couplings has been compiled to show how new interactions modify stability of the electroweak vacuum. Whereas it is possible to stabilize the SM by adding Planck scale suppressed interactions and taking into account running of the new couplings, the generic effect is shortening the lifetime and hence further destabilisation of the SM electroweak vacuum. These findings have been illustrated with phase diagrams of modified SM-like models. It has been demonstrated that stabilisation can be achieved by lowering the suppression scale of higher order operators while picking up such combinations of new couplings, which do not deepen the new minima of the potential. Our results show the dependence of the lifetime of the electroweak minimum on the magnitude of the new couplings, including cases with very small couplings (which means very large effective suppression scale) and couplings vastly different in magnitude (which corresponds to two different suppression scales).

Zygmunt Lalak; Marek Lewicki; Pawel Olszewski

2014-02-16

410

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

411

Electrical Strength of Multilayer Vacuum Insulators  

SciTech Connect

The electrical strength of vacuum insulators is a key constraint in the design of particle accelerators and pulsed power systems. Vacuum insulating structures assembled from alternating layers of metal and dielectric can result in improved performance compared to conventional insulators, but previous attempts to optimize their design have yielded seemingly inconsistent results. Here, we present two models for the electrical strength of these structures, one assuming failure by vacuum arcing between adjacent metal layers and the other assuming failure by vacuum surface flashover. These models predict scaling laws which are in agreement with the experimental data currently available.

Harris, J R; Kendig, M; Poole, B; Sanders, D M; Caporaso, G J

2008-07-01

412

Cold vacuum drying facility design requirements  

SciTech Connect

This document provides the detailed design requirements for the Spent Nuclear Fuel Project Cold Vacuum Drying Facility. Process, safety, and quality assurance requirements and interfaces are specified.

IRWIN, J.J.

1999-07-01

413

Attractor Explosions and Catalyzed Vacuum Decay  

E-print Network

We present a mechanism for catalyzed vacuum bubble production obtained by combining moduli stabilization with a generalized attractor phenomenon in which moduli are sourced by compact objects. This leads straightforwardly to a class of examples in which the Hawking decay process for black holes unveils a bubble of a different vacuum from the ambient one, generalizing the new endpoint for Hawking evaporation discovered recently by Horowitz. Catalyzed vacuum bubble production can occur for both charged and uncharged bodies, including Schwarzschild black holes for which massive particles produced in the Hawking process can trigger vacuum decay. We briefly discuss applications of this process to the population and stability of metastable vacua.

Daniel Green; Eva Silverstein; David Starr

2006-05-04

414

Laser-dressed vacuum polarization in a Coulomb field  

SciTech Connect

We investigate quantum electrodynamic effects under the influence of an external, time-dependent electromagnetic field, which mediates dynamic modifications of the radiative corrections. Specifically, we consider the quantum electrodynamic vacuum-polarization tensor under the influence of two external background fields: a strong laser field and a nuclear Coulomb field. We calculate the charge and current densities induced by a nuclear Coulomb field in the presence of a laser field. We find the corresponding induced scalar and vector potentials. The induced potential, in first-order perturbation theory, leads to a correction to atomic energy levels. The external laser field breaks the rotational symmetry of the system. Consequently, the induced charge density is not spherically symmetric, and the energy correction therefore leads to a ''polarized Lamb shift.'' In particular, the laser generates an additional potential with a quadrupole moment. The corresponding laser-dressed vacuum-polarization potential behaves like 1/r{sup 3} at large distances, unlike the Uehling potential, which vanishes exponentially for large r. The energy corrections are of the same order of magnitude for hydrogenic levels, irrespective of the angular momentum quantum number. The induced current leads to a transition dipole moment which oscillates at the second harmonic of the laser frequency and is mediated by second-order harmonic generation in the vacuum-polarization loop. In the far field, at distances r>>1/{omega} from the nucleus ({omega} is the laser frequency), the laser induces mutually perpendicular electric and magnetic fields, which give rise to an energy flux that corresponds to photon fusion leading to the generation of real photons, again at the second harmonic of the laser. Our investigation might be useful for other situations where quantum field theoretic phenomena are subjected to external fields of a rather involved structure.

Milstein, A. I.; Terekhov, I. S.; Jentschura, U. D.; Keitel, C. H. [Budker Institute of Nuclear Physics, 630090 Novosibirsk (Russian Federation); Max-Planck-Institut fuer Kernphysik, Saupfercheckweg 1, 69117 Heidelberg (Germany)

2005-11-15

415

Effect of current annealing on electronic properties of multilayer graphene  

NASA Astrophysics Data System (ADS)

While ideal graphene has high mobility due to the relativistic nature of carriers, it is known that the carrier transport in actual graphene samples is dominated by the influence of scattering from charged impurities, which almost conceals the intrinsic splendid properties of this novel material. The common techniques to improve the graphene mobility include the annealing in hydrogen atmosphere and the local annealing by imposing a large biasing current. Although annealing is quite important technique for the experimental study of graphene, detailed evaluation of the annealing effect is lacking at present. In this paper, we study the effect of the current annealing in multilayer graphene devices quantitatively by investigating the change in the mobility and the carrier density at the charge neutrality point. We find that the current annealing sometimes causes degradation of the transport properties.

Tanaka, S.; Goto, H.; Tomori, H.; Ootuka, Y.; Tsukagoshi, K.; Kanda, A.

2010-06-01

416

Study on thermal annealing of cadmium zinc telluride (CZT) crystals  

SciTech Connect

Cadmium Zinc Telluride (CZT) has attracted increasing interest with its promising potential as a room-temperature nuclear-radiation-detector material. However, different defects in CZT crystals, especially Te inclusions and dislocations, can degrade the performance of CZT detectors. Post-growth annealing is a good approach potentially to eliminate the deleterious influence of these defects. At Brookhaven National Laboratory (BNL), we built up different facilities for investigating post-growth annealing of CZT. Here, we report our latest experimental results. Cd-vapor annealing reduces the density of Te inclusions, while large temperature gradient promotes the migration of small-size Te inclusions. Simultaneously, the annealing lowers the density of dislocations. However, only-Cd-vapor annealing decreases the resistivity, possibly reflecting the introduction of extra Cd in the lattice. Subsequent Te-vapor annealing is needed to ensure the recovery of the resistivity after removing the Te inclusions.

Yang, G.; Bolotnikov, A.E.; Fochuk, P.M.; Camarda, G.S.; Cui, Y.; Hossain, A.; Kim, K.; Horace, J.; McCall, B.; Gul, R.; Xu, L.; Kopach, O.V.; and James, R.B.

2010-08-01

417

Surface morphology of annealed titanium /silicon bilayer in the presence of oxygen  

SciTech Connect

The evolution of surface morphology and chemical composition of vacuum-annealed titanium films deposited on Si(111) substrate with native oxide is investigated. We show that changes in topography and chemical composition of the surface are related to the simultaneous transport of Si and oxygen. The elucidation of this process is done through a combined use of atomic force microscopy, scanning spreading resistance imaging, x-ray photoelectron spectroscopy, and secondary ion mass spectrometry depth profiling. Coalescence of TiO{sub 2} columnar grains formed on the silicide surface results in the coarsening of the surface. Variations in root-mean-square roughness of the surface oxide in the presence of the silicide is compared with that of pure titanium oxide for similar heat-treatment conditions.

Ilango, S.; Raghavan, G.; Kamruddin, M.; Bera, Santanu; Tyagi, A.K. [Indira Gandhi Centre for Atomic Research, Kalpakkam 603 102, Tamil Nadu (India)

2005-09-05

418

The annealing behavior of implanted nitrogen in fcc stainless steel  

Microsoft Academic Search

Post-implantation annealing of N-implanted 304 stainless steel at 400 °C has been investigated by conversion electron Mössbauer spectroscopy, X-ray diffraction and Auger electron spectroscopy. After a 1 h anneal, the near complete dissolution of the as-implanted Fe2N-like nitride phase results in a 9 at.% N fcc solid-solution phase. After the final anneal (64 h), N has diffused to a depth

O. Ozturk; D. L. Williamson

1994-01-01

419

Continuous stress annealing of amorphous ribbons for strain sensing applications  

Microsoft Academic Search

Stress-annealed amorphous Co69Fe2Cr7Si8B14 ribbons are suitable materials for strain sensors required in civil engineering applications. The equipments for the continuous stress-annealing of ribbons and the automatic homogeneity test of magnetic properties are described. The magnetic properties of stress-annealed ribbons are discussed. The use of ribbon in an inductive strain sensor is also illustrated.

Lud?k Kraus; Jan Bydžovský; Peter Švec

2003-01-01

420

Effect of annealing history on free volume in thermoplastics  

NASA Technical Reports Server (NTRS)

Two different types of thermoplastic glassy polymers have been investigated for the effects of thermal annealing on their free volumes. It has been observed that free volumes in glassy polymers decrease asymptotically to a steady level after about four thermal anneals lasting for 24 hours at a temperature about 50 C below their glass transition temperatures. These results indicate that composites incorporating properly annealed thermoplastic matrices may not experience any additional internal stresses due to subsequent thermal excursions experienced while in service.

Singh, J. J.; St.clair, T. L.

1986-01-01

421

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

422

Fermion Mass Mixing in Vacuum  

NASA Astrophysics Data System (ADS)

Renormalization group procedure for effective particles is applied to a theory of fermions that interact only through mass mixing terms in their Hamiltonian. Problems with virtual pair production in vacuum are avoided by using the front form of Hamiltonian dynamics. Masses and states of physical fermions emerge at the end of a calculation that is carried out exactly irrespective of the strength of the mass mixing terms. An a priori infinite set of renormalization group equations for all momentum modes of fermion quantum fields is reduced to just one equation for a two-by-two mass matrix. In distinction from scalars, fermions never become tachyons but appear chirally rotated when the mass mixing interaction term is sufficiently strong.

G?azek, Stanis?aw D.

2014-06-01

423

Pressure/vacuum relief valve  

SciTech Connect

This patent describes a pressure/vacuum relief valve for a fluid containing vessel. It comprises: an elongated cylinder having a wall and having end walls closing the cylinder ends, one end portion of the cylinder wall having a first port communicating with the fluid in the vessel and the other end portion of the cylinder having a second port communicating with the atmosphere; a piston in the cylinder normally sealed with the inner wall surface thereof between the first and second ports; a piston rod axially projecting from the piston through the respective cylinder end wall; elongated cage means having a closed end and an open end axially connected with the respective cylinder end wall around the respective end portion of the piston rod; and, pressure responsive elongated pin means interposed between the respective end of the piston rod and the closed end of the respective cage for normally maintaining the piston in valve closed position.

Taylor, J.S.

1990-12-18

424

TRIUMF cyclotron vacuum system refurbishing  

NASA Astrophysics Data System (ADS)

The cyclotron at TRIUMF was commissioned to full energy in 1974. The volume of the cyclotron vacuum tank is about 100 m3 and it operates at 5×10-8 Torr pressure during beam production. The pumping is mainly based on a Phillips B-20 cryogenerator (Stirling cycle 4-cylinder engine). The cryogenerator supplies helium gas at 16 K and 70 K to cryopanels in the tank. The decreasing reliability of the B-20 and demanding maintenance requirements triggered the decision to completely overhaul or replace the cryogenerator. Replacement with the LINDE-1630 helium refrigerator was found to be the most attractive (technically and economically) option. The details of the proposal with installation of the helium refrigerator and with a continuous flow liquid nitrogen shield cooling system are presented.

Sekachev, I.

2008-03-01

425

SXLS Phase 2 vacuum system  

SciTech Connect

Phase 1 of the SXLS (Superconducting X-Ray Lithography Source) is described. It is a room temperature, racetrack-shaped electron storage ring, 8.5 meters in circumference. The Phase 2 design consists of replacing the two room temperature 180{degree} dipole magnets of Phase 1 with superconducting magnets. However, even though superconducting magnets are used, the vacuum chambers within them will operate at room temperature. The chambers are constructed as weldments and are made of INCONEL-625. They are bakeable to 150{degrees}C in-situ and incorporate nine photon beam ports. Each have built-in distributed sputter-ion pumps (DIP), non-evaporable getter (NEG) pumps, beam position monitors, and ion clearing electrodes. R D is underway to optimize the DIP, which much operate at 3.86 Tesla, and to develop a low photo yield coating or treatment for the internal surfaces of the chambers.

Schuchman, J.C.; Chou, T.S.; Halama, H.; Hsieh, H.; Kim, T.; Pjerov, S.; Staicu, F.

1991-01-01

426

Coherence Phenomena in Coupled Optical Resonators  

NASA Technical Reports Server (NTRS)

We predict a variety of photonic coherence phenomena in passive and active coupled ring resonators. Specifically, the effective dispersive and absorptive steady-state response of coupled resonators is derived, and used to determine the conditions for coupled-resonator-induced transparency and absorption, lasing without gain, and cooperative cavity emission. These effects rely on coherent photon trapping, in direct analogy with coherent population trapping phenomena in atomic systems. We also demonstrate that the coupled-mode equations are formally identical to the two-level atom Schrodinger equation in the rotating-wave approximation, and use this result for the analysis of coupled-resonator photon dynamics. Notably, because these effects are predicted directly from coupled-mode theory, they are not unique to atoms, but rather are fundamental to systems of coherently coupled resonators.

Smith, D. D.; Chang, H.

2004-01-01

427

How Might You Investigate Scientific Phenomena?  

NSDL National Science Digital Library

This site, part of Exploring Earth Investigation by McDougal Littell and TERC, examines how to investigate scientific phenomena. The investigations "were designed to build students' knowledge of Earth Science conceptsâ¦and to raise student awareness of Earth as a system of interconnected components and processes." Here, visitors will learn about the steps that allow scientists to create valid investigations of phenomena: forming a hypothesis, determining the appropriate method of investigation, collecting and graphing data, and hypothesis testing. Many sections have illustrative images and interactive features which help students understand the topics presented, and the final section ends with questions for students to further explore as well as a link to some NASA datasets. This is an excellent site for any Earth Science classroom as an introductory lecture to the scientific method or as an out-of-class exploration for students.

2008-09-05

428

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

429

Annealing of phosphorus-doped Ge islands on Si(001)  

NASA Astrophysics Data System (ADS)

To study the effect of phosphorus on the evolution of Ge islands on Si(001), phosphorus-doped islands were annealed in a H2 ambient and undoped islands were annealed in a PH3/H2 ambient. In both cases phosphorus stabilizes the island structure and reduces coarsening during annealing. The changes of island shape during annealing are consistent with phosphorus influencing the thermodynamic properties of the islands, while the slower decrease in the density of islands when phosphorus is present is consistent with phosphorus kinetically retarding surface diffusion of Ge atoms.

Kamins, T. I.; Medeiros-Ribeiro, G.; Ohlberg, D. A. A.; Williams, R. Stanley

2004-02-01

430

Discharge Properties and Emitted Electromagnetic Wave Spectrum in Low Vacuum Region of Vacuum Interrupter  

Microsoft Academic Search

Study on reliability of vacuum interrupter (VI) such as detection method of the slow leak has been extensively carried out, while study on discharge properties in low vacuum of VI is still insufficient. In this report, we experimentally investigated discharge properties inside VI under closed contact and open contact conditions of main contactors in low vacuum of VI to simulate

Mohamad Kamarol; Shinya Ohtsuka; Hitoshi Saitou; Masayuki Sakaki; Masayuki Hikita

2005-01-01

431

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

432

Emission phenomena in a SHS combustion wave  

Microsoft Academic Search

There are numerous experimental data indicating that the action of electromagnetic and magnetic fields on the combustion wave\\u000a of self-propagating high-temperature synthesis (SHS) changes the process kinetics and the structure and properties of the\\u000a reaction products. Emission phenomena in the combustion wave have received less attention. High rates of chemical energy dissipation\\u000a in SHS (1012 W\\/m3) are accompanied by physical

Yu. M. Maksimov; A. I. Kirdyashkin; R. M. Gabbasov; V. G. Salamatov

2009-01-01

433

SUPERCONVERGENCE PHENOMENA ON THREE-DIMENSIONAL MESHES  

Microsoft Academic Search

We give an overview of superconvergence phenomena in the flnite element method for solving three-dimensional problems, in particular, for el- liptic boundary value problems of second order over uniform meshes. Some di-culties with superconvergence on tetrahedral meshes are presented as well. For a given positive integer m we prove that there is no tetrahedralization of R3 whose all edges are

MICHAL K

434

Detonation wave phenomena in bubbled liquid  

Microsoft Academic Search

Shock wave propagation was investigated in two phase media consisting of diluted glycerin (85%) and reactive gas bubbles. To understand these complex phenomena, we first performed a numerical analysis and experimental studies of single bubbles containing a reactive gas-mixture. For the two-phase mixtures, a needle matrix bubble-generator enabled us to produce a homogeneous bubble distribution with a size dispersion less

A. E. Beylich

1990-01-01

435

Detonation wave phenomena in bubbled liquid  

Microsoft Academic Search

Shock wave propagation was investigated in two phase media consisting of diluted glycerin (85%) and reactive gas bubbles. To understand these complex phenomena, we first performed a numerical analysis and experimental studies of single bubbles containing a reactive gas-mixture. For the two-phase mixtures, a needle matrix bubble-generator enabled us to produce a homogeneous bubble distribution with a size dispersion less

A. Gülhan; A. E. Beylich

1990-01-01

436

Observations of Cometary Plasma Wave Phenomena  

Microsoft Academic Search

The ICE plasma wave investigation utilized very long electric antennas (90 meters tip-to-tip) and a very high sensitivity magnetic search coil to obtain: (1) significant local information on plasma physics phenomena occurring in the distant pickup regions of comet Giacobini-Zinner and comet P\\/Halley, and (2) information on the processes that developed in the coma and tail of Giacobini-Zinner. Since ICE

F. L. Scarfe; V. F. Coroniti; C. F. Kennel; D. A. Gurnett; W. H. Ip; E. J. Smith

1987-01-01

437

Stratospheric pollution related ultraviolet radiation phenomena  

Microsoft Academic Search

RBsumB. - Une revue concise des phCnom6nes ultraviolets qui jouent un r6le dans la pollution stratospherique est prCsentCe. Son but est de mettre en Cvidence les aspects principaux par des exemples rkcents. L'accent est place sur les nouvelles donnCes obtenues depuis sept ans au sujet du rayonnement ultraviolet solaire. Abstract. - A short review of ultraviolet phenomena related to stratospheric

M. Ackerman

1978-01-01

438

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

439

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

2013-04-02

440

Evolution of uranium dislocation structure at different-rate deformation and different-temperature annealing  

NASA Astrophysics Data System (ADS)

The Williamson-Hall method based on analyzing the angular dependence of diffraction maximum broadening is used to study the dislocation structure. Densities of chaotically arranged dislocations on samples after their different-rate deformation are measured. Consideration is given to the dislocation structure of a spherical uranium sample after its shock-wave loading, as well as to the dislocation structure of model samples deformed at the rate of ˜ 10-3s-1 up to 5%, 20%, and 60% relative deformation. After deformation, samples were vacuum annealed at 200C, 400C, 600C, 720C, and 850C (in alpha-, beta-, and gamma-phases). Samples were cooled at the rate of ˜ 10?/min. Results for samples subjected to different-rate deformation and different-temperature annealing are compared. In the dislocation structure of the sample recovered after shock-wave loading, special features that cannot be described with the help of mechanisms observed at the low-rate deformation and cooling were elucidated. Systematic investigations of the uranium dislocation structure at the increasing speed of loading are to be continued).

Shestakov, A. E.; Artamonov, I. V.

2012-08-01

441

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

442

Optical contamination during thermal testing in vacuum  

NASA Technical Reports Server (NTRS)

Comparative tests are described for optical degradation in vacuum systems served by oil-type or ion-type pumping operation. Results show that degradation occurs only during ultraviolet irradiation in vacuum systems with oil-type pumping systems and that it increases with exposure time. Degradation does not occur with ion systems.

Zwiener, J. M.

1970-01-01

443

Thermal versus vacuum magnetization in QED  

Microsoft Academic Search

The magnetized relativistic Fermi and Bose gases are studied at finite temperature and density.In the case of the Fermi gas, the contribution to the magnetization from the vacuum becomes dominant for high magnetic fields, when the thermal contribution saturates. In the case of the charged Bose gas, the (paramagnetic) vacuum--magnetization becomes dominant when the gas changes from a diamagnetic to

P Elmfors; P Liljenberg; D Persson; B S Skagerstam

1994-01-01

444

Vacuum in Gas and Fluid Dynamics  

Microsoft Academic Search

\\u000a In this paper, we review some interesting problems of vacuum states arising in hyperbolic conservations laws with applications\\u000a to gas and fluid dynamics. We present the current status of the understanding of compressible Euler flows near vacuum and\\u000a discuss related open problems.

Juhi Jang; Nader Masmoudi

445

Vacuum pyrolysis of PVC I. Kinetic study  

Microsoft Academic Search

Vacuum pyrolysis of PVC has been studied emphasizing two aspects: the kinetics of PVC pyrolysis reactions and the yields of pyrolysis products. The purpose of the kinetic study is to identify each apparent reaction involved in PVC pyrolysis. Three stages of weight loss have been evidenced by TG analysis during PVC decomposition both under vacuum and in nitrogen atmosphere, while

Rosa Miranda; Jin Yang; Christian Roy; Cornelia Vasile

1999-01-01

446

Vacuum chamber for an undulator straight section  

SciTech Connect

A prototype aluminum extruded vacuum chamber for an undulator straight section of the Advanced Photon Source is described. The 52.-m long vacuum system is designed so that the undulator gap variation does not interfere with it. The chamber is gripped in a stiff close toleranced mounting structure to insure dimensional tolerance of the chamber height.

Kim, S.; Wehrle, R.; Genens, L.

1987-01-01

447

Dark energy and quantum vacuum fluctuations  

E-print Network

It is suggested that the vacuum expectation of the quantum vacuum energy-momentum is zero, but quantum fluctuations give rise to a space-time curvature equivalent to that of a cosmological constant or dark energy. Calculations within quantized gravity, following a few plausible hypotheses, provide results compatible with cosmological observations.

Emilio Santos

2009-02-25

448

Vacuum structure and high-energy scattering  

E-print Network

This short review deals with the manifestations of the vacuum structure of non-Abelian gauge theories in high-energy scattering. Specifically, it concentrates on instanton-induced hard scattering processes, both in the electroweak gauge theory and in QCD. Soft scattering processes in QCD and their connection to models of semi-hard vacuum fluctuations are also briefly discussed.

A. Ringwald

2002-10-15

449

Vacuum Energy: If Not Now, Then When?  

E-print Network

We review the cosmological evidence for a low matter density universe and a cosmological constant or dynamical vacuum energy and address the cosmolog$ coincidence problem: why is the matter density about one-half the vacuum energy {\\em now}. This is reasonble, following the anthropic argument of Efstathiou and of Martel, Schapiro & Weinberg.

Sidney A. Bludman

1999-07-13

450

On the Vacuum Propagation of Gravitational Waves  

E-print Network

We show that, for any local, causal quantum field theory which couples covariantly to gravity, and which admits Minkowski spacetime vacuum(a) invariant under the inhomogeneous proper orthochronous Lorentz group, plane gravitational waves propagating in such Minkowski vacuum(a) do not dissipate energy or momentum via quantum field theoretic effects.

Xiao Liu

2007-06-04

451

On Gauge Invariance and Vacuum Polarization  

Microsoft Academic Search

This paper is based on the elementary remark that the extraction of gauge invariant results from a formally gauge invariant theory is ensured if one employs methods of solution that involve only gauge covariant quantities. We illustrate this statement in connection with the problem of vacuum polarization by a prescribed electromagnetic field. The vacuum current of a charged Dirac field,

Julian Schwinger

1951-01-01

452

Vacuum vessel and pumping system of TEXTOR  

Microsoft Academic Search

The designs of the vacuum vessel and pumping system of the TEXTOR toroidal plasma experiment are presented. The vacuum vessel is an all-metal welded torus consisting of four large and four small rigid sections connected by eight bellows sections, and can be heated up to 400 C. Numerous portholes are provided for diagnostics, as well as pumping units, divertors and

D. A. Butzek; K. Derichs; W. Graf; A. Cosler; K. H. Dippel; M. Schuerer; W. Bieger

1979-01-01

453

Preliminary Study on Arc Welding in Vacuum  

Microsoft Academic Search

Welding technology in space is required to repair the space station. Arc welding in vacuum should be more conventional than electron beam welding because of low voltage operation. Preliminary study on vacuum arc welding is presented in this paper. Arc was ignited by separating an arcing electrode (cathode) from the welding piece (anode). The former is composed of a rod

H. Toya; K. Hieda; T. Saitou

2006-01-01

454

ALUMINUM ALLOY VACUUM CHAMBERS FOR SSRF  

Microsoft Academic Search

The antechamber type vacuum system design is chosen in the SSRF storage ring. Each vacuum chamber is machined from two thick plates of A5083-H321 aluminum alloy and welded at their perimeter. The complex structure and the high dimensional precision requirement are the features of these chambers. Some new ideas are adopted in the structure design to decrease the deflection. The

Lixin Yin; Dikui Jiang; Hanwen Du; Xiaoli Jiang

455

String Field Theory Around the Tachyon Vacuum  

Microsoft Academic Search

Assuming that around the tachyon vacuum the kinetic term of cubic open string field theory is made purely of ghost operators we are led to gauge invariant actions which manifestly implement the absence of open string dynamics around this vacuum. We test this proposal by showing the existence of lump solutions of arbitrary codimension in this string field theory. The

Leonardo Rastelli; Ashoke Sen; Barton Zwiebach

2000-01-01

456

Physicochemical Properties Changes of Donuts During Vacuum Frying  

Microsoft Academic Search

Vacuum frying was explored to cook donuts and compared to the conventional atmospheric frying. A temperature of 190°C was used for atmospheric frying. Three vacuum levels (3, 6, and 9 kPa vacuum) with three temperature levels (150, 165, and 180°C) were used for vacuum frying. The effects of initial moisture content (IMC), vacuum level and frying temperature on physicochemical properties,

K. J. Tan; G. S. Mittal

2006-01-01

457

Mechanism of morphology transformation during annealing of nanostructured gold films on glass.  

PubMed

Nanostructured, just-percolated gold films were prepared by evaporation on bare glass. Annealing of the films at temperatures close to or higher than the softening temperature of the glass substrate induces morphological transformation to discrete Au islands and gradual embedding of the formed islands in the glass. The mechanism and kinetics of these processes are studied here using a combination of in situ high-temperature optical spectroscopy; ex situ characterization of the island shape by high-resolution scanning electron microscopy (HRSEM), atomic force microcopy (AFM) and cross-sectional transmission electron microscopy (TEM); and numerical simulations of transmission spectra using the Multiple Multipole Program (MMP) approach. It is shown that the morphological transformation of just-percolated, 10 nm (nominal thickness) Au films evaporated on glass and annealed at 600 °C, i.e., in the vicinity of the substrate glass transition temperature (Tg = 557 °C), proceeds via three processes exhibiting different time scales: (i) fast recrystallization and dewetting, leading to formation of single-crystalline islands (minutes); the initial spectrum characteristic of a continuous Au film is transformed to that of an island film, displaying a surface plasmon (SP) absorption band. (ii) Reshaping and faceting of the single-crystalline islands accompanied by formation of circumferential glass rims around them (first few hours); the overall optical response shows a blue shift of the SP band. (iii) Gradual island embedding in the glass substrate (tens of hours), seen as a characteristic red shift of the SP band. The influence of the annealing atmosphere (air, vacuum) on the embedding process is found to be minor. Numerical modeling of the extinction cross-section corresponding to the morphological transformations during island recrystallization and embedding is in qualitative agreement with the experimental data. PMID:23440015

Karakouz, Tanya; Tesler, Alexander B; Sannomiya, Takumi; Feldman, Yishay; Vaskevich, Alexander; Rubinstein, Israel

2013-04-01

458

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

459

Vacuum deposition and curing of liquid monomers  

DOEpatents

The present invention is the formation of solid polymer layers under vacuum. More specifically, the present invention is the use of standard polymer layer-making equipment that is generally used in an atmospheric environment in a vacuum, and degassing the monomer material prior to injection into the vacuum. Additional layers of polymer or metal may be vacuum deposited onto solid polymer layers. Formation of polymer layers under a vacuum improves material and surface characteristics, and subsequent quality of bonding to additional layers. Further advantages include use of less to no photoinitiator for curing, faster curing, fewer impurities in the polymer electrolyte, as well as improvement in material properties including no trapped gas resulting in greater density, and reduced monomer wetting angle that facilitates spreading of the monomer and provides a smoother finished surface.

Affinito, J.D.

1993-11-09

460

Vacuum deposition and curing of liquid monomers  

DOEpatents

The present invention is the formation of solid polymer layers under vacuum. More specifically, the present invention is the use of "standard" polymer layer-making equipment that is generally used in an atmospheric environment in a vacuum, and degassing the monomer material prior to injection into the vacuum. Additional layers of polymer or metal may be vacuum deposited onto solid polymer layers. Formation of polymer layers under a vacuum improves material and surface characteristics, and subsequent quality of bonding to additional layers. Further advantages include use of less to no photoinitiator for curing, faster curing, fewer impurities in the polymer electrolyte, as well as improvement in material properties including no trapped gas resulting in greater density, and reduced monomer wetting angle that facilitates spreading of the monomer and provides a smoother finished surface.

Affinito, John D. (Richland, WA)

1993-01-01

461

Vacuum deposition and curing of liquid monomers  

DOEpatents

The present invention is the formation of solid polymer layers under vacuum. More specifically, the present invention is the use of "standard" polymer layer-making equipment that is generally used in an atmospheric environment in a vacuum, and degassing the monomer material prior to injection into the vacuum. Additional layers of polymer or metal or oxide may be vacuum deposited onto solid polymer layers. Formation of polymer layers under a vacuum improves material and surface characteristics, and subsequent quality of bonding to additional layers. Further advantages include use of less to no photoinitiator for curing, faster curing, fewer impurities in the polymer electrolyte, as well as improvement in material properties including no trapped gas resulting in greater density, and reduced monomer wetting angle that facilitates spreading of the monomer and provides a smoother finished surface.

Affinito, John D. (Kennewick, WA)

1995-01-01

462

Vacuum deposition and curing of liquid monomers  

DOEpatents

The present invention is the formation of solid polymer layers under vacuum. More specifically, the present invention is the use of ``standard`` polymer layer-making equipment that is generally used in an atmospheric environment in a vacuum, and degassing the monomer material prior to injection into the vacuum. Additional layers of polymer or metal or oxide may be vacuum deposited onto solid polymer layers. Formation of polymer layers under a vacuum improves material and surface characteristics, and subsequent quality of bonding to additional layers. Further advantages includ