Vacuum energy density kicked by the electroweak crossover

NASA Astrophysics Data System (ADS)

Klinkhamer, F. R.; Volovik, G. E.

2009-10-01

Using q-theory, we show that the electroweak crossover can generate a remnant vacuum energy density Λ˜Eew8/EPlanck4, with effective electroweak energy scale Eew˜103GeV and reduced Planck-energy scale EPlanck˜1018GeV. The obtained expression for the effective cosmological constant Λ may be a crucial input for the suggested solution by Arkani-Hamed et al. of the triple cosmic coincidence puzzle (why the orders of magnitude of the energy densities of vacuum, matter, and radiation are approximately the same in the present Universe).

Gravitational vacuum energy in our recently accelerating universe

NASA Astrophysics Data System (ADS)

Bludman, Sidney

2009-04-01

We review current observations of the homogeneous cosmological expansion which, because they measure only kinematic variables, cannot determine the dynamics driving the recent accelerated expansion. The minimal fit to the data, the flat ACDM model, consisting of cold dark matter and a cosmological constant, interprets 4? geometrically as a classical spacetime curvature constant of nature, avoiding any reference to quantum vacuum energy. (The observed Uehling and Casimir effects measure forces due to QED vacuum polarization, but not any quantum material vacuum energies.) An Extended Anthropic Principle, that Dark Energy and Dark Gravity be indistinguishable, selects out flat ACDM. Prospective cosmic shear and galaxy clustering observations of the growth of fluctuations are intended to test whether the 'dark energy' driving the recent cosmological acceleration is static or moderately dynamic. Even if dynamic, observational differences between an additional negative-pressure material component within general relativity (Dark Energy) and low-curvature modifications of general relativity (Dark Gravity) will be extremely small.

Nonperturbative vacuum polarization effects in two-dimensional supercritical Dirac-Coulomb system II. Vacuum energy

NASA Astrophysics Data System (ADS)

Davydov, A.; Sveshnikov, K.; Voronina, Yu.

2018-01-01

Nonperturbative vacuum polarization effects are explored for a supercritical Dirac-Coulomb system with Z > Zcr,1 in 2+1D, based on the original combination of analytical methods, computer algebra and numerical calculations, proposed recently in Refs. 1-3. Both the vacuum charge density ρV P(r→) and vacuum energy ℰV P are considered. Due to a lot of details of calculation the whole work is divided into two parts I and II. Taking account of results, obtained in the part I4 for ρV P, in the present part II, the evaluation of the vacuum energy ℰV P is investigated with emphasis on the renormalization and convergence of the partial expansion for ℰV P. It is shown that the renormalization via fermionic loop turns out to be the universal tool, which removes the divergence of the theory both in the purely perturbative and essentially nonperturbative regimes of the vacuum polarization. The main result of calculation is that for a wide range of the system parameters in the overcritical region ℰV P turns out to be a rapidly decreasing function ˜-ηeffZ3/R with ηeff > 0 and R being the size of the external Coulomb source. To the end the similarity in calculations of ℰV P in 2+1 and 3+1D is discussed, and qualitative arguments are presented in favor of the possibility for complete screening of the classical electrostatic energy of the Coulomb source by the vacuum polarization effects for Z ≫ Zcr,1 in 3+1D.

Obstetric management in vacuum-extraction deliveries.

PubMed

Ahlberg, Mia; Saltvedt, Sissel; Ekéus, Cecilia

2016-06-01

The aim of this observational study was to describe the obstetric management in vacuum extraction (VE) deliveries and to compare these findings to instructions in clinical guidelines on VE. In 2013, detailed data on management of 600 VE cases were consecutively collected from six different delivery units in Sweden. Each unit also contributed their own clinical VE guideline. In total, 93% of the VEs ended with a vaginal delivery while 7% failed and were converted to an emergency cesarean section. In 2.3% extraction time exceeded 20 minutes, and in 6% more than six pulls were used to deliver the fetus. Cup detachment occurred in 14.6%, and fundal pressure was used in 11% of the deliveries. In 2.3%, fetal station was assessed as above the level of the maternal ischial spines. The clinical guidelines on VE varied in scope and content between units, and were often incomplete according to best practice. The vast majority of the VEs were conducted in accordance with safety recommendations. However, in a few extractions, safety rules were disregarded and more than six pulls or an extraction time of more than 20 minutes were used to complete the delivery. Copyright © 2016 Elsevier B.V. All rights reserved.

Removal of caffeine from green tea by microwave-enhanced vacuum ice water extraction.

PubMed

Lou, Zaixiang; Er, Chaojuan; Li, Jing; Wang, Hongxin; Zhu, Song; Sun, Juntao

2012-02-24

In order to selectively remove caffeine from green tea, a microwave-enhanced vacuum ice water extraction (MVIE) method was proposed. The effects of MVIE variables including extraction time, microwave power, and solvent to solid radio on the removal yield of caffeine and the loss of total phenolics (TP) from green tea were investigated. The optimized conditions were as follows: solvent (mL) to solid (g) ratio was 10:1, microwave extraction time was 6 min, microwave power was 350 W and 2.5 h of vacuum ice water extraction. The removal yield of caffeine by MVIE was 87.6%, which was significantly higher than that by hot water extraction, indicating a significant improvement of removal efficiency. Moreover, the loss of TP of green tea in the proposed method was much lower than that in the hot water extraction. After decaffeination by MVIE, the removal yield of TP tea was 36.2%, and the content of TP in green tea was still higher than 170 mg g(-1). Therefore, the proposed microwave-enhanced vacuum ice water extraction was selective, more efficient for the removal of caffeine. The main phenolic compounds of green tea were also determined, and the results indicated that the contents of several catechins were almost not changed in MVIE. This study suggests that MVIE is a new and good alternative for the removal of caffeine from green tea, with a great potential for industrial application. Copyright © 2011 Elsevier B.V. All rights reserved.

Quantum vacuum energy in general relativity

NASA Astrophysics Data System (ADS)

Henke, Christian

2018-02-01

The paper deals with the scale discrepancy between the observed vacuum energy in cosmology and the theoretical quantum vacuum energy (cosmological constant problem). Here, we demonstrate that Einstein's equation and an analogy to particle physics leads to the first physical justification of the so-called fine-tuning problem. This fine-tuning could be automatically satisfied with the variable cosmological term Λ (a)=Λ_0+Λ_1 a^{-(4-ɛ)}, 0 < ɛ ≪ 1, where a is the scale factor. As a side effect of our solution of the cosmological constant problem, the dynamical part of the cosmological term generates an attractive force and solves the missing mass problem of dark matter.

Terra Vac In Situ Vacuum Extraction System: Applications Analysis Report

EPA Science Inventory

This document is an evaluation of the Terra Vac in situ vacuum extraction system and its applicability as a treatment method for waste site cleanup. This report analyzes the results from the Superfund Innovative Technology Evaluation (SITE) Program’s 56-day demonstration at t...

Vacuum Pump System Optimization Saves Energy at a Dairy Farm

DOE Office of Scientific and Technical Information (OSTI.GOV)

None

In 1998, S&S Dairy optimized the vacuum pumping system at their dairy farm in Modesto, California. In an effort to reduce energy costs, S&S Dairy evaluated their vacuum pumping system to determine if efficiency gains and energy savings were possible.

Cosmic vacuum energy decay and creation of cosmic matter.

PubMed

Fahr, Hans-Jörg; Heyl, Michael

2007-09-01

In the more recent literature on cosmological evolutions of the universe, the cosmic vacuum energy has become a nonrenouncable ingredient. The cosmological constant Lambda, first invented by Einstein, but later also rejected by him, presently experiences an astonishing revival. Interestingly enough, it acts like a constant vacuum energy density would also do. Namely, it has an accelerating action on cosmic dynamics, without which, as it appears, presently obtained cosmological data cannot be conciliated with theory. As we are going to show in this review, however, the concept of a constant vacuum energy density is unsatisfactory for very basic reasons because it would claim for a physical reality that acts upon spacetime and matter dynamics without itself being acted upon by spacetime or matter.

Cosmological constant problem and renormalized vacuum energy density in curved background

DOE Office of Scientific and Technical Information (OSTI.GOV)

Kohri, Kazunori; Matsui, Hiroki, E-mail: kohri@post.kek.jp, E-mail: matshiro@post.kek.jp

The current vacuum energy density observed as dark energy ρ{sub dark}≅ 2.5×10{sup −47} GeV{sup 4} is unacceptably small compared with any other scales. Therefore, we encounter serious fine-tuning problem and theoretical difficulty to derive the dark energy. However, the theoretically attractive scenario has been proposed and discussed in literature: in terms of the renormalization-group (RG) running of the cosmological constant, the vacuum energy density can be expressed as ρ{sub vacuum}≅ m {sup 2} H {sup 2} where m is the mass of the scalar field and rather dynamical in curved spacetime. However, there has been no rigorous proof to derivemore » this expression and there are some criticisms about the physical interpretation of the RG running cosmological constant. In the present paper, we revisit the RG running effects of the cosmological constant and investigate the renormalized vacuum energy density in curved spacetime. We demonstrate that the vacuum energy density described by ρ{sub vacuum}≅ m {sup 2} H {sup 2} appears as quantum effects of the curved background rather than the running effects of cosmological constant. Comparing to cosmological observational data, we obtain an upper bound on the mass of the scalar fields to be smaller than the Planck mass, m ∼< M {sub Pl}.« less

Relaxation of vacuum energy in q-theory

NASA Astrophysics Data System (ADS)

Klinkhamer, F. R.; Savelainen, M.; Volovik, G. E.

2017-08-01

The q-theory formalism aims to describe the thermodynamics and dynamics of the deep quantum vacuum. The thermodynamics leads to an exact cancellation of the quantum-field zero-point-energies in equilibrium, which partly solves the main cosmological constant problem. But, with reversible dynamics, the spatially flat Friedmann-Robertson-Walker universe asymptotically approaches the Minkowski vacuum only if the Big Bang already started out in an initial equilibrium state. Here, we extend q-theory by introducing dissipation from irreversible processes. Neglecting the possible instability of a de-Sitter vacuum, we obtain different scenarios with either a de-Sitter asymptote or collapse to a final singularity. The Minkowski asymptote still requires fine-tuning of the initial conditions. This suggests that, within the q-theory approach, the decay of the de-Sitter vacuum is a necessary condition for the dynamical solution of the cosmological constant problem.

PERFORMANCE OF AIR SPARGING AND SOIL VACUUM EXTRACTION FOR TREATMENT OF MTBE AND BENZENE AT UST SITES IN KANSAS

EPA Science Inventory

The efficacy of soil vacuum extraction or air sparging and soil vacuum extraction for remediation of ground water contamination with MTBE was compared to remediation of contamination with benzene. There was no practical difference.
Sites were identified that met the followin...

Vacuum Energy Induced by AN Impenetrable Flux Tube of Finite Radius

NASA Astrophysics Data System (ADS)

Gorkavenko, V. M.; Sitenko, Yu. A.; Stepanov, O. B.

2011-06-01

We consider the effect of the magnetic field background in the form of a tube of the finite transverse size on the vacuum of the quantized charged massive scalar field which is subject to the Dirichlet boundary condition at the edge of the tube. The vacuum energy is induced, being periodic in the value of the magnetic flux enclosed in the tube. The dependence of the vacuum energy density on the distance from the tube and on the coupling to the space-time curvature scalar is comprehensively analyzed.

Vacuum Energy Induced by AN Impenetrable Flux Tube of Finite Radius

NASA Astrophysics Data System (ADS)

Gorkavenko, V. M.; Sitenko, Yu. A.; Stepanov, O. B.

We consider the effect of the magnetic field background in the form of a tube of the finite transverse size on the vacuum of the quantized charged massive scalar field which is subject to the Dirichlet boundary condition at the edge of the tube. The vacuum energy is induced, being periodic in the value of the magnetic flux enclosed in the tube. The dependence of the vacuum energy density on the distance from the tube and on the coupling to the space-time curvature scalar is comprehensively analyzed.

Technically natural vacuum energy at the tip of a supersymmetric teardrop

NASA Astrophysics Data System (ADS)

Williams, Matthew

2014-04-01

A minimal supersymmetric braneworld model is presented which has (i) zero classical four-dimensional vacuum curvature, despite the large naive vacuum energy due to contributions from Standard Model particles and (ii) one-(bulk)-loop quantum corrections to the vacuum energy with a size set by the radius of the extra-dimensional spheroid. These corrections are technically natural because a Bogomol'nyi-Prasad-Sommerfield-like relation between the brane tension and R charge—which would have preserved (half of) the bulk supersymmetry—is violated by the requirement that the stabilizing R-symmetry gauge flux be quantized. The extra-dimensional geometry is similar to previous rugby-ball geometries, but is simpler in that there is only one brane and so fewer free parameters. Although the sign of the renormalized vacuum energy ends up being the unphysical one for this model (in the limit considered here, where the massive bulk loop is the leading contribution), it serves as an illustrative example of the relevant physics.

High-Energy Vacuum Birefringence and Dichroism in an Ultrastrong Laser Field

NASA Astrophysics Data System (ADS)

Bragin, Sergey; Meuren, Sebastian; Keitel, Christoph H.; Di Piazza, Antonino

2017-12-01

A long-standing prediction of quantum electrodynamics, yet to be experimentally observed, is the interaction between real photons in vacuum. As a consequence of this interaction, the vacuum is expected to become birefringent and dichroic if a strong laser field polarizes its virtual particle-antiparticle dipoles. Here, we derive how a generally polarized probe photon beam is influenced by both vacuum birefringence and dichroism in a strong linearly polarized plane-wave laser field. Furthermore, we consider an experimental scheme to measure these effects in the nonperturbative high-energy regime, where the Euler-Heisenberg approximation breaks down. By employing circularly polarized high-energy probe photons, as opposed to the conventionally considered linearly polarized ones, the feasibility of quantitatively confirming the prediction of nonlinear QED for vacuum birefringence at the 5 σ confidence level on the time scale of a few days is demonstrated for upcoming 10 PW laser systems. Finally, dichroism and anomalous dispersion in vacuum are shown to be accessible at these facilities.

Regenerated silica gel as stationary phase on vacuum column chromatography to purify temulawak's extracts

NASA Astrophysics Data System (ADS)

Cahyono, Bambang; Maduwu, Ratna Dewi; Widayat, Suzery, Meiny

2015-12-01

Commercial silica gel only used once by many researchers and affected high cost for purification process, also less support the green chemistry program. This research focused in regeneration silica gel that used purification of temulawak's extracts (Curcuma xanthorrhiza Roxb) by vacuum column chromatography. Sample extracts (contains 10.1195±0.5971% of curcuminoids) was purified by vacuum column chromatography (pressure: 45 kPa, column: 100mm on length and 16mm on diameter). Ethanol 96% and acetone were compared as eluent. The amount of solvent and yield of curcuminoids used as indicator purification. The silica gel was regenerated with heating in 600°C for 8 hours The silica gels were analyzed by IR spectroscopy and X-ray diffraction. Furthermore, regenerated silica gel was used as the stationary phase in vacuum column chromatography under the same conditions with the previous purification. All the purification experiments were performed in three repetitions. Based on regression equation, y=0.132x+0.0011 (r2=0.9997) the yield of curcuminoids on purified products using ethanol as the eluent was improved 4.26% (to 14.3724±0.5749%) and by acetone was improved 3,03% (to 13.1450 ±0.6318%). The IR spectrum of both silica gel showed the same vibration profile and also there were three crystallinity peaks missing on its X-ray diffraction. Regenerated silica gel has the same performance with new silica gel in purification of temulawak's extract: by ethanol has increased 4.08% (14.1947±0.7415%) and 2.93% (13.0447±0.4822) by acetone. In addition, all purification products showed similar TLC profiles. Purification using regenerated silica gel as the adsorbent on vacuum column chromatography has exactly same potential with the new silica gel.

Ultrasound-assisted extraction coupled with under vacuum distillation of flavour compounds from spearmint (carvone-rich) plants: Comparison with conventional hydrodistillation.

PubMed

Da Porto, Carla; Decorti, Deborha

2009-08-01

Ultrasonically assisted extraction of flavour compounds from different varieties of Mentha spicata, using 70% ethanol, have been carried out for 5, 10 and 15min and coupled with under vacuum distillation. The ultrasound distilled extracts have been analysed by GC-MS and compared with essential oils obtained by hydrodistillation. The results have showed that ultrasonically assisted extraction in combination with under vacuum distillation have provided extracts with higher flavouring strength due to the increased concentration of desirable oxygenated compounds (from 5 to 8 times) compared with hydrodistillation. Extraction yields of flavour volatiles have been calculated giving a range 0.04-0.13% by ultrasound and 0.01-0.02% by hydrodistillation.

Static black hole and vacuum energy: thin shell and incompressible fluid

NASA Astrophysics Data System (ADS)

Ho, Pei-Ming; Matsuo, Yoshinori

2018-03-01

With the back reaction of the vacuum energy-momentum tensor consistently taken into account, we study static spherically symmetric black-hole-like solutions to the semi-classical Einstein equation. The vacuum energy is assumed to be given by that of 2-dimensional massless scalar fields, as a widely used model in the literature for black holes. The solutions have no horizon. Instead, there is a local minimum in the radius. We consider thin shells as well as incompressible fluid as the matter content of the black-hole-like geometry. The geometry has several interesting features due to the back reaction of vacuum energy. In particular, Buchdahl's inequality can be violated without divergence in pressure, even if the surface is below the Schwarzschild radius. At the same time, the surface of the star can not be far below the Schwarzschild radius for a density not much higher than the Planck scale, and the proper distance from its surface to the origin can be very short even for very large Schwarzschild radius. The results also imply that, contrary to the folklore, in principle the Boulware vacuum can be physical for black holes.

An effective vacuum assisted extraction method for the optimization of labdane diterpenoids from Andrographis paniculata by response surface methodology.

PubMed

Wang, Ya-Qi; Wu, Zhen-Feng; Ke, Gang; Yang, Ming

2014-12-31

An effective vacuum assisted extraction (VAE) technique was proposed for the first time and applied to extract bioactive components from Andrographis paniculata. The process was carefully optimized by response surface methodology (RSM). Under the optimized experimental conditions, the best results were obtained using a boiling temperature of 65 °C, 50% ethanol concentration, 16 min of extraction time, one extraction cycles and a 12:1 liquid-solid ratio. Compared with conventional ultrasonic assisted extraction and heat reflux extraction, the VAE technique gave shorter extraction times and remarkable higher extraction efficiency, which indicated that a certain degree of vacuum gave the solvent a better penetration of the solvent into the pores and between the matrix particles, and enhanced the process of mass transfer. The present results demonstrated that VAE is an efficient, simple and fast method for extracting bioactive components from A. paniculata, which shows great potential for becoming an alternative technique for industrial scale-up applications.

Vacuum system of the compact Energy Recovery Linac

DOE Office of Scientific and Technical Information (OSTI.GOV)

Honda, T., E-mail: tohru.honda@kek.jp; Tanimoto, Y.; Nogami, T.

2016-07-27

The compact Energy Recovery Linac (cERL), a test accelerator to establish important technologies demanded for future ERL-based light sources, was constructed in late 2013 at KEK. The accelerator was successfully commissioned in early 2014, and demonstrated beam circulation with energy recovery. In the cERL vacuum system, low-impedance vacuum components are required to circulate high-intensity, low-emittance and short-bunch electron beams. We therefore developed ultra-high-vacuum (UHV)-compatible flanges that can connect beam tubes seamlessly, and employed retractable beam monitors, namely, a movable Faraday cup and screen monitors. In most parts of the accelerator, pressures below 1×10{sup −7} Pa are required to mitigate beam-gasmore » interactions. Particularly, near the photocathode electron gun and the superconducting (SC) cavities, pressures below 1×10{sup −8} Pa are required. The beam tubes in the sections adjoining the SC cavities were coated with non-evaporable getter (NEG) materials, to reduce gas condensation on the cryo-surfaces. During the accelerator commissioning, stray magnetic fields from the permanent magnets of some cold cathode gauges (CCGs) were identified as a source of the disturbance to the beam orbit. Magnetic shielding was specially designed as a remedy for this issue.« less

Vacuum arc plasma thrusters with inductive energy storage driver

NASA Technical Reports Server (NTRS)

Schein, Jochen (Inventor); Gerhan, Andrew N. (Inventor); Woo, Robyn L. (Inventor); Au, Michael Y. (Inventor); Krishnan, Mahadevan (Inventor)

2004-01-01

An apparatus for producing a vacuum arc plasma source device using a low mass, compact inductive energy storage circuit powered by a low voltage DC supply acts as a vacuum arc plasma thruster. An inductor is charged through a switch, subsequently the switch is opened and a voltage spike of Ldi/dt is produced initiating plasma across a resistive path separating anode and cathode. The plasma is subsequently maintained by energy stored in the inductor. Plasma is produced from cathode material, which allows for any electrically conductive material to be used. A planar structure, a tubular structure, and a coaxial structure allow for consumption of cathode material feed and thereby long lifetime of the thruster for long durations of time.

Proceedings of the twenty sixth international symposium on discharges and electrical insulation in vacuum. V. 2

DOE Office of Scientific and Technical Information (OSTI.GOV)

NONE

2014-07-01

Vacuum science and technology has made vital contributions in high technology areas like space, high energy particle accelerators, plasma devices, pulse power, electronics, vacuum interrupters, thin films, melting and refining of metals/alloys, extraction and processing of advanced materials. Vacuum discharges, vacuum arc physics and technology and various applications towards vacuum interrupters, pulse power and particle accelerator are the main themes for this symposium. Papers relevant to INIS are indexed separately.

Proceedings of the twenty sixth international symposium on discharges and electrical insulation in vacuum. V. 1

DOE Office of Scientific and Technical Information (OSTI.GOV)

NONE

2014-07-01

Vacuum science and technology has made vital contributions in high technology areas like space, high energy particle accelerators, plasma devices, pulse power, electronics, vacuum interrupters, thin films, melting and refining of metals/alloys, extraction and processing of advanced materials. Vacuum discharges, vacuum arc physics and technology and various applications towards vacuum interrupters, pulse power and particle accelerator are the main themes for this symposium. Papers relevant to INIS are indexed separately.

Regenerated silica gel as stationary phase on vacuum column chromatography to purify temulawak’s extracts

DOE Office of Scientific and Technical Information (OSTI.GOV)

Cahyono, Bambang; Maduwu, Ratna Dewi; Widayat,

Commercial silica gel only used once by many researchers and affected high cost for purification process, also less support the green chemistry program. This research focused in regeneration silica gel that used purification of temulawak’s extracts (Curcuma xanthorrhiza Roxb) by vacuum column chromatography. Sample extracts (contains 10.1195±0.5971% of curcuminoids) was purified by vacuum column chromatography (pressure: 45 kPa, column: 100mm on length and 16mm on diameter). Ethanol 96% and acetone were compared as eluent. The amount of solvent and yield of curcuminoids used as indicator purification. The silica gel was regenerated with heating in 600°C for 8 hours The silica gelsmore » were analyzed by IR spectroscopy and X-ray diffraction. Furthermore, regenerated silica gel was used as the stationary phase in vacuum column chromatography under the same conditions with the previous purification. All the purification experiments were performed in three repetitions. Based on regression equation, y=0.132x+0.0011 (r{sup 2}=0.9997) the yield of curcuminoids on purified products using ethanol as the eluent was improved 4.26% (to 14.3724±0.5749%) and by acetone was improved 3,03% (to 13.1450 ±0.6318%). The IR spectrum of both silica gel showed the same vibration profile and also there were three crystallinity peaks missing on its X-ray diffraction. Regenerated silica gel has the same performance with new silica gel in purification of temulawak’s extract: by ethanol has increased 4.08% (14.1947±0.7415%) and 2.93% (13.0447±0.4822) by acetone. In addition, all purification products showed similar TLC profiles. Purification using regenerated silica gel as the adsorbent on vacuum column chromatography has exactly same potential with the new silica gel.« less

Final Report - Energy Reduction and Advanced Water Removal via Membrane Solvent Extraction Technology

DOE Office of Scientific and Technical Information (OSTI.GOV)

Reed, John; Fanselow, Dan; Abbas, Charles

2014-08-06

3M and Archer Daniels Midland (ADM) collaborated with the U.S. Department of Energy (DOE) to develop and demonstrate a novel membrane solvent extraction (MSE) process that can substantially reduce energy and water consumption in ethanol production, and accelerate the fermentation process. A cross-flow membrane module was developed, using porous membrane manufactured by 3M. A pilot process was developed that integrates fermentation, MSE and vacuum distillation. Extended experiments of 48-72 hours each were conducted to develop the process, verify its performance and begin establishing commercial viability.

An étude on global vacuum energy sequester

DOE PAGES

D’Amico, Guido; Kaloper, Nemanja; Padilla, Antonio; ...

2017-09-18

Recently two of the authors proposed a mechanism of vacuum energy sequester as a means of protecting the observable cosmological constant from quantum radiative corrections. The original proposal was based on using global Lagrange multipliers, but later a local formulation was provided. Subsequently other interesting claims of a different non-local approach to the cosmological constant problem were made, based again on global Lagrange multipliers. We examine some of these proposals and find their mutual relationship. We explain that the proposals which do not treat the cosmological constant counterterm as a dynamical variable require fine tunings to have acceptable solutions. Furthermore,more » the counterterm often needs to be retuned at every order in the loop expansion to cancel the radiative corrections to the cosmological constant, just like in standard GR. These observations are an important reminder of just how the proposal of vacuum energy sequester avoids such problems.« less

Homogenate-assisted Vacuum-powered Bubble Extraction of Moso Bamboo Flavonoids for On-line Scavenging Free Radical Capacity Analysis.

PubMed

Sun, Yinnan; Yang, Kui; Cao, Qin; Sun, Jinde; Xia, Yu; Wang, Yinhang; Li, Wei; Ma, Chunhui; Liu, Shouxin

2017-07-11

A homogenate-assisted vacuum-powered bubble extraction (HVBE) method using ethanol was applied for extraction of flavonoids from Phyllostachys pubescens (P. pubescens) leaves. The mechanisms of homogenate-assisted extraction and vacuum-powered bubble generation were discussed in detail. Furthermore, a method for the rapid determination of flavonoids by HPLC was established. HVBE followed by HPLC was successfully applied for the extraction and quantification of four flavonoids in P. pubescens , including orientin, isoorientin, vitexin, and isovitexin. This method provides a fast and effective means for the preparation and determination of plant active components. Moreover, the on-line antioxidant capacity, including scavenging positive ion and negative ion free radical capacity of different fractions from the bamboo flavonoid extract was evaluated. Results showed that the scavenging DPPH ˙ free radical capacity of vitexin and isovitexin was larger than that of isoorientin and orientin. On the contrary, the scavenging ABTS⁺ ˙ free radical capacity of isoorientin and orientin was larger than that of vitexin and isovitexin.

The Influence of AN Interacting Vacuum Energy on the Gravitational Collapse of a Star Fluid

NASA Astrophysics Data System (ADS)

Campos, M.

2014-02-01

To explain the accelerated expansion of the universe, models with interacting dark components has been considered in the literature. Generally, the dark energy component is physically interpreted as the vacuum energy. However, at the other side of the same coin, the influence of the vacuum energy in the gravitational collapse is a topic of scientific interest. Based in a simple assumption on the collapsed rate of the matter fluid density that is altered by the inclusion of a vacuum energy component that interacts with the matter fluid, we study the final fate of the collapse process.

EPA SITE DEMONSTRATION OF THE TERRA VAC IN SITU VACUUM EXTRACTION PROCESS IN GROVELAND, MASSACHUSETTS

EPA Science Inventory

This paper presents an EPA evaluation of the patented Terra Vac, Inc.'s in situ vacuum extraction process that was field-demonstrated on a trichloroethylene (TCE) contaminated soil in Groveland, MA, under the EPA Superfund Innovative Technology Evaluation (SITE) program. he Terra...

High energy density capacitors for vacuum operation with a pulsed plasma load

NASA Technical Reports Server (NTRS)

Guman, W. J.

1976-01-01

Results of the effort of designing, fabricating, and testing of a 40 joules/lb (88.2 joules/Kg) high voltage energy storage capacitor suitable for operating a pulsed plasma thruster in a vacuum environment for millions of pulses are presented. Using vacuum brazing and heli-arc welding techniques followed by vacuum and high pressure helium leak tests it was possible to produce a hermetically sealed relatively light weight enclosure for the dielectric system. An energy density of 40 joules/lb was realized with a KF-polyvinylidene fluoride dielectric system. One capacitor was D.C. life tested at 4 KV (107.8 joules/lb) for 2,000 hours before it failed. Another exceeded 2,670 hours without failure at 38.3 joules/lb. Pulse life testing in a vacuum exceeded 300,000 discharges with testing still in progress. The D.C. life test data shows a small decrease in capacitance and an increase in dissipation factor with time. Heat transfer from the load to the capacitor must also be considered besides the self-heat generated by the capacitor.

Sequestration of vacuum energy and the end of the universe.

PubMed

Kaloper, Nemanja; Padilla, Antonio

2015-03-13

Recently, we proposed a mechanism for sequestering the standard model vacuum energy that predicts that the Universe will collapse. Here we present a simple mechanism for bringing about this collapse, employing a scalar field whose potential is linear and becomes negative, providing the negative energy density required to end the expansion. The slope of the potential is chosen to allow for the expansion to last until the current Hubble time, about 10^{10} years, to accommodate our Universe. Crucially, this choice is technically natural due to a shift symmetry. Moreover, vacuum energy sequestering selects radiatively stable initial conditions for the collapse, which guarantee that immediately before the turnaround the Universe is dominated by the linear potential which drives an epoch of accelerated expansion for at least an e fold. Thus, a single, technically natural choice for the slope ensures that the collapse is imminent and is preceded by the current stage of cosmic acceleration, giving a new answer to the "why now?"

Vacuum insulation of the high energy negative ion source for fusion application.

PubMed

Kojima, A; Hanada, M; Hilmi, A; Inoue, T; Watanabe, K; Taniguchi, M; Kashiwagi, M; Umeda, N; Tobari, H; Kobayashi, S; Yamano, Y; Grisham, L R

2012-02-01

Vacuum insulation on a large size negative ion accelerator with multiple extraction apertures and acceleration grids for fusion application was experimentally examined and designed. In the experiment, vacuum insulation characteristics were investigated in the JT-60 negative ion source with >1000 apertures on the grid with the surface area of ∼2 m(2). The sustainable voltages varied with a square root of the gap lengths between the grids, and decreased with number of the apertures and with the surface area of the grids. Based on the obtained results, the JT-60SA (super advanced) negative ion source is designed to produce 22 A, 500 keV D(-) ion beams for 100 s.

An ultrahigh vacuum, low-energy ion-assisted deposition system for III-V semiconductor film growth

NASA Astrophysics Data System (ADS)

Rohde, S.; Barnett, S. A.; Choi, C.-H.

1989-06-01

A novel ion-assisted deposition system is described in which the substrate and growing film can be bombarded with high current densities (greater than 1 mA/sq cm) of very low energy (10-200 eV) ions. The system design philosophy is similar to that used in III-V semiconductor molecular-beam epitaxy systems: the chamber is an all-metal ultrahigh vacuum system with liquid-nitrogen-cooled shrouds, Knudsen-cell evaporation sources, a sample insertion load-lock, and a 30-kV reflection high-energy electron diffraction system. III-V semiconductor film growth is achieved using evaporated group-V fluxes and group-III elemental fluxes sputtered from high-purity targets using ions extracted from a triode glow discharge. Using an In target and an As effusion cell, InAs deposition rates R of 2 microns/h have been obtained. Epitaxial growth of InAs was observed on both GaSb(100) and Si(100) substrates.

Vacuum insulation of the high energy negative ion source for fusion application

DOE Office of Scientific and Technical Information (OSTI.GOV)

Kojima, A.; Hanada, M.; Inoue, T.

2012-02-15

Vacuum insulation on a large size negative ion accelerator with multiple extraction apertures and acceleration grids for fusion application was experimentally examined and designed. In the experiment, vacuum insulation characteristics were investigated in the JT-60 negative ion source with >1000 apertures on the grid with the surface area of {approx}2 m{sup 2}. The sustainable voltages varied with a square root of the gap lengths between the grids, and decreased with number of the apertures and with the surface area of the grids. Based on the obtained results, the JT-60SA (super advanced) negative ion source is designed to produce 22 A,more » 500 keV D{sup -} ion beams for 100 s.« less

Vacuum Permeator Analysis for Extraction of Tritium from DCLL Blankets

DOE Office of Scientific and Technical Information (OSTI.GOV)

Humrickhouse, Paul Weston; Merrill, Brad Johnson

2014-11-01

It is envisioned that tritium will be extracted from DCLL blankets using a vacuum permeator. We derive here an analytical solution for the extraction efficiency of a permeator tube, which is a function of only two dimensionless numbers: one that indicates whether radial transport is limited in the PbLi or in the solid membrane, and another that is the ratio of axial and radial transport times in the PbLi. The permeator efficiency is maximized by decreasing the velocity and tube diameter, and increasing the tube length. This is true regardless of the mass transport correlation used; we review several heremore » and find that they differ little, and the choice of correlation is not a source of significant uncertainty here. The PbLi solubility, on the other hand, is a large source of uncertainty, and we identify upper and lower bounds from the literature data. Under the most optimistic assumptions, we find that a ferritic steel permeator operating at 550 °C will need to be at least an order of magnitude larger in volume than previous conceptual designs using niobium and operating at higher temperatures.« less

An explanation for the tiny value of the cosmological constant and the low vacuum energy density

NASA Astrophysics Data System (ADS)

Nassif, Cláudio

2015-09-01

The paper aims to provide an explanation for the tiny value of the cosmological constant and the low vacuum energy density to represent the dark energy. To accomplish this, we will search for a fundamental principle of symmetry in space-time by means of the elimination of the classical idea of rest, by including an invariant minimum limit of speed in the subatomic world. Such a minimum speed, unattainable by particles, represents a preferred reference frame associated with a background field that breaks down the Lorentz symmetry. The metric of the flat space-time shall include the presence of a uniform vacuum energy density, which leads to a negative pressure at cosmological length scales. Thus, the equation of state for the cosmological constant [ p(pressure) (energy density)] naturally emerges from such a space-time with an energy barrier of a minimum speed. The tiny values of the cosmological constant and the vacuum energy density will be successfully obtained, being in agreement with the observational results of Perlmutter, Schmidt and Riess.

Static black holes with back reaction from vacuum energy

NASA Astrophysics Data System (ADS)

Ho, Pei-Ming; Matsuo, Yoshinori

2018-03-01

We study spherically symmetric static solutions to the semi-classical Einstein equation sourced by the vacuum energy of quantum fields in the curved space-time of the same solution. We found solutions that are small deformations of the Schwarzschild metric for distant observers, but without horizon. Instead of being a robust feature of objects with high densities, the horizon is sensitive to the energy–momentum tensor in the near-horizon region.

Implementation of EPICS based vacuum control system for variable energy cyclotron centre, Kolkata

NASA Astrophysics Data System (ADS)

Roy, Anindya; Bhole, R. B.; Nandy, Partha P.; Yadav, R. C.; Pal, Sarbajit; Roy, Amitava

2015-03-01

The vacuum system of the Room Temperature (K = 130) Cyclotron of Variable Energy Cyclotron Centre is comprised of vacuum systems of main machine and Beam Transport System. The vacuum control system is upgraded to a PLC based Automated system from the initial relay based Manual system. The supervisory control of the vacuum system is implemented in Experimental Physics and Industrial Control System (EPICS). An EPICS embedded ARM based vacuum gauge controller is developed to mitigate the requirement of vendor specific gauge controller for gauges and also for seamless integration of the gauge controllers with the control system. A set of MS-Windows ActiveX components with embedded EPICS Channel Access interface are developed to build operator interfaces with less complex programming and to incorporate typical Windows feature, e.g., user authentication, file handling, better fonts, colors, mouse actions etc. into the operator interfaces. The control parameters, monitoring parameters, and system interlocks of the system are archived in MySQL based EPICS MySQL Archiver developed indigenously. In this paper, we describe the architecture, the implementation details, and the performance of the system.

Implementation of EPICS based vacuum control system for variable energy cyclotron centre, Kolkata.

PubMed

Roy, Anindya; Bhole, R B; Nandy, Partha P; Yadav, R C; Pal, Sarbajit; Roy, Amitava

2015-03-01

The vacuum system of the Room Temperature (K = 130) Cyclotron of Variable Energy Cyclotron Centre is comprised of vacuum systems of main machine and Beam Transport System. The vacuum control system is upgraded to a PLC based Automated system from the initial relay based Manual system. The supervisory control of the vacuum system is implemented in Experimental Physics and Industrial Control System (EPICS). An EPICS embedded ARM based vacuum gauge controller is developed to mitigate the requirement of vendor specific gauge controller for gauges and also for seamless integration of the gauge controllers with the control system. A set of MS-Windows ActiveX components with embedded EPICS Channel Access interface are developed to build operator interfaces with less complex programming and to incorporate typical Windows feature, e.g., user authentication, file handling, better fonts, colors, mouse actions etc. into the operator interfaces. The control parameters, monitoring parameters, and system interlocks of the system are archived in MySQL based EPICS MySQL Archiver developed indigenously. In this paper, we describe the architecture, the implementation details, and the performance of the system.

High-energy vacuum birefringence and dichroism in an ultrastrong laser field

NASA Astrophysics Data System (ADS)

Meuren, Sebastian; Bragin, Sergey; Keitel, Christoph H.; di Piazza, Antonino

2017-10-01

The interaction between real photons in vacuum is a long-standing prediction of quantum electrodynamics, which has never been observed experimentally. Upcoming 10 PW laser systems like the Extreme Light Infrastructure (ELI) will provide laser pulses with unprecedented intensities. If combined with highly energetic gamma photons - obtainable via Compton backscattering from laser-wakefield accelerated electron beams - the QED critical field becomes accessible. In we have derived how a generally polarized probe photon beam is influenced by both vacuum birefringence and dichroism in a strong linearly polarized plane-wave laser field. We put forward an experimental scheme to measure these effects in the nontrivial high-energy regime, where the QED critical field is reached and the Euler-Heisenberg approximation, valid for low-frequency electromagnetic fields, breaks down. Our results suggest the feasibility of verifying/rejecting the QED prediction for vacuum birefringence/dichroism at the 3 σ confidence level on the time scale of a few days at several upcoming laser facilities. Now at Princeton University, Princeton, NJ.

Application of ionic liquids in vacuum microwave-assisted extraction followed by macroporous resin isolation of three flavonoids rutin, hyperoside and hesperidin from Sorbus tianschanica leaves.

PubMed

Gu, Huiyan; Chen, Fengli; Zhang, Qiang; Zang, Jing

2016-03-01

Rutin, hyperoside and hesperidin were effectively extracted from Sorbus tianschanica leaves by an ionic liquid vacuum microwave-assisted method. A series of ionic liquids with various anions and alkyl chain length of the cations were studied and the extraction was performed in [C6mim][BF4] aqueous solution. After optimization by a factorial design and response surface methodology, total extraction yield of 2.37mg/g with an error of 0.12mg/g (0.71±0.04mg/g, 1.18±0.06mg/g and 0.48±0.02 for rutin, hyperoside and hesperidin, respectively) was achieved under -0.08MPa for vacuum, 19min and 420W for microwave irradiation time and power, and 15mL/g for liquid-solid ratio. The proposed method here is more efficient and needs a shorter extraction time for rutin, hyperoside and hesperidin from S. tianschanica leaves than reference extraction techniques. In stability studies performed with standard rutin, hyperoside and hesperidin, the target analytes were stable under the optimum conditions. The proposed method had a high reproducibility and precision. In addition, separation of rutin, hyperoside and hesperidin from [C6mim][BF4] extraction solution was completed effectively by AB-8 macroporous resin adsorption and desorption process. Ionic liquid vacuum microwave-assisted extraction is a simple, rapid and efficient sample extraction technique. Copyright © 2016 Elsevier B.V. All rights reserved.

Implementation of EPICS based vacuum control system for variable energy cyclotron centre, Kolkata

DOE Office of Scientific and Technical Information (OSTI.GOV)

Roy, Anindya, E-mail: r-ani@vecc.gov.in; Bhole, R. B.; Nandy, Partha P.

2015-03-15

The vacuum system of the Room Temperature (K = 130) Cyclotron of Variable Energy Cyclotron Centre is comprised of vacuum systems of main machine and Beam Transport System. The vacuum control system is upgraded to a PLC based Automated system from the initial relay based Manual system. The supervisory control of the vacuum system is implemented in Experimental Physics and Industrial Control System (EPICS). An EPICS embedded ARM based vacuum gauge controller is developed to mitigate the requirement of vendor specific gauge controller for gauges and also for seamless integration of the gauge controllers with the control system. A setmore » of MS-Windows ActiveX components with embedded EPICS Channel Access interface are developed to build operator interfaces with less complex programming and to incorporate typical Windows feature, e.g., user authentication, file handling, better fonts, colors, mouse actions etc. into the operator interfaces. The control parameters, monitoring parameters, and system interlocks of the system are archived in MySQL based EPICS MySQL Archiver developed indigenously. In this paper, we describe the architecture, the implementation details, and the performance of the system.« less

[Assessment of vacuum-assisted vaginal delivery in a frank breech presentation].

PubMed

Bleu, G; Deruelle, P; Demetz, J; Michel, S; Dufour, P; Depret, S; Subtil, D

2015-02-01

After verification of the eligibility criteria and with an obstetrician familiar with the specific maneuvers likely to be needed, vaginal delivery of breech presentations is possible. If problems arise during the active pushing phase of labor, vacuum extraction has been described in the literature for this uncommon condition with limited series. The aim of this study is to assess retrospectively vacuum extraction in frank breech presentation in our center. This retrospective study of trials of vaginal delivery of fetuses in breech presentation at term compares cases according to whether they did or did not use a vacuum extraction. During a two-year period, 83 patients, whom had trials of vaginal delivery in breech presentations, reached the active pushing/bearing down stage after complete cervical dilatation. Vacuum assistance was applied in six of these (7.2 %). The failure rate for vaginal delivery was significantly higher in the group with compared to without vacuum extraction (33.3 % versus 6.5 %, P<0.05). Moreover, the mean pH at birth was significantly lower in the group with vacuum extraction (7.12±0.11 versus 7.20±0.08, P<0.05), and these infants more frequently had deep cutaneous injuries (66.7 % versus 26.0 %, P<0.05). In fetuses in breech presentation, when vaginal delivery failed, it seems to be safer for the fetuses to perform caesarean section rather than attempt vacuum extraction. Copyright © 2015 Elsevier Masson SAS. All rights reserved.

Study of Vacuum Energy Physics for Breakthrough Propulsion

NASA Technical Reports Server (NTRS)

Millis, Marc G. (Technical Monitor); Maclay, G. Jordan; Hammer, Jay; Clark, Rod; George, Michael; Kim, Yeong; Kir, Asit

2004-01-01

This report summarizes the accomplishments during a three year research project to investigate the use of surfaces, particularly in microelectromechanical systems (MEMS), to exploit quantum vacuum forces. During this project, we developed AFM instrumentation to repeatably measure Casimir forces in the nanoNewton range at 10 6 torr, designed an experiment to measure attractive and repulsive quantum vacuum forces, developed a QED based theory of Casimir forces that includes non-ideal material properties for rectangular cavities and for multilayer slabs, developed theoretical models for a variety of microdevices utilizing vacuum forces, applied vacuum physics to a gedanken spacecraft, and investigated a new material with a negative index of refraction.

Risk factors for anal sphincter tears in vacuum-assisted delivery.

PubMed

Ryman, P; Ahlberg, M; Ekéus, C

2015-10-01

The aim of the present study was to describe the prevalence of anal sphincter tears (AST) in relation to obstetric management and technique during vacuum extraction deliveries (VE) (re: indications, the station of the fetal head at application of the cup, number of tractions, the length for the extraction, cup detachments, pain relief, episiotomy, fetal presentation, and experience of the operator) as well as maternal and infant anthropometrics. Descriptive study. Data on six hundred vacuum extraction deliveries were consecutively collected from six different delivery units in Sweden. Each unit contributed with data on 100 deliveries. The final study population included 596 women who delivered by vacuum extraction. There was no correlation between the management of the vacuum extraction and risk for anal sphincter tear. Women from Africa had nearly a fourfold risk for anal sphincter tear during vacuum-assisted delivery compared with Swedish-born women (OR 3.82 CI 1.47-9.89). Compared with infants with birth weight less than 4000 g, birth weight above 4000 g was associated with increased risk of AST (OR 1.87 CI 1.06-3.28). In this study, the obstetric management in VE-assisted deliveries did not impact the risk of AST. Copyright © 2015 Elsevier B.V. All rights reserved.

Antimicrobial activity of several herb and spice extracts in culture medium and in vacuum-packaged pork.

PubMed

Kong, Baohua; Wang, Jinzhi; Xiong, Youling L

2007-03-01

Extracts prepared from honeysuckle, Scutellaria, Forsythia suspensa (Thunb), cinnamon, and rosemary with 75% ethanol and from clove oil dissolved in 75% ethanol were applied to inoculated agar media to observe their inhibitory effects on the growth of Escherichia coli, Pseudomonas fluorescens, and Lactobacillus plantarum. All the extracts suppressed the growth of these bacteria; Scutellaria exhibited the strongest effect against E. coli. An orthogonal test revealed that the most effective antimicrobial composite extracts were equal-volume mixtures of 0.125 g/ml Scutellaria + 0.5 g/ml honeysuckle + 0.125 g/ml Forsythia + 0.25 g/ml cinnamon and 0.25 g/ml cinnamon + 0.125 g/ml rosemary + 0.25% clove oil. These mixed extracts also produced strong antimicrobial effects in vacuum-packaged fresh pork, with 1.81- to 2.32-log reductions in microbial counts compared with the control when stored for up to 28 days. The sensory panel detected minimal differences in surface color and off-odors between meat samples treated with herb-spice extracts and the control. These results indicate that combined herb and spice extracts can be used as natural antimicrobials for food preservation.

Possible signals of vacuum dynamics in the Universe

NASA Astrophysics Data System (ADS)

Peracaula, Joan Solà; de Cruz Pérez, Javier; Gómez-Valent, Adrià

2018-05-01

We study a generic class of time-evolving vacuum models which can provide a better phenomenological account of the overall cosmological observations as compared to the ΛCDM. Among these models, the running vacuum model (RVM) appears to be the most motivated and favored one, at a confidence level of ˜3σ. We further support these results by computing the Akaike and Bayesian information criteria. Our analysis also shows that we can extract fair signals of dynamical dark energy (DDE) by confronting the same set of data to the generic XCDM and CPL parametrizations. In all cases we confirm that the combined triad of modern observations on Baryonic Acoustic Oscillations, Large Scale Structure formation, and the Cosmic Microwave Background, provide the bulk of the signal sustaining a possible vacuum dynamics. In the absence of any of these three crucial data sources, the DDE signal can not be perceived at a significant confidence level. Its possible existence could be a cure for some of the tensions existing in the ΛCDM when confronted to observations.

The localized quantum vacuum field

NASA Astrophysics Data System (ADS)

Dragoman, D.

2008-03-01

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.

Cosmological implications of the transition from the false vacuum to the true vacuum state

NASA Astrophysics Data System (ADS)

Stachowski, Aleksander; Szydłowski, Marek; Urbanowski, Krzysztof

2017-06-01

We study cosmology with running dark energy. The energy density of dark energy is obtained from the quantum process of transition from the false vacuum state to the true vacuum state. We use the Breit-Wigner energy distribution function to model the quantum unstable systems and obtain the energy density of the dark energy parametrization ρ _ {de}(t). We also use Krauss and Dent's idea linking properties of the quantum mechanical decay of unstable states with the properties of the observed Universe. In the cosmological model with this parametrization there is an energy transfer between dark matter and dark energy. The intensity of this process, measured by a parameter α , distinguishes two scenarios. As the Universe starts from the false vacuum state, for the small value of α (0<α <0.4) it goes through an intermediate oscillatory (quantum) regime of the density of dark energy, while for α > 0.4 the density of the dark energy jumps down. In both cases the present value of the density of dark energy is reached. From a statistical analysis we find this model to be in good agreement with the astronomical data and practically indistinguishable from the Λ CDM model.

Antilisterial activity and consumer acceptance of irradiated chicken breast meat vacuum-infused with grape seed and green tea extracts and tartaric acid.

PubMed

Over, K F; Hettiarachchy, N S; Perumalla, A V S; Johnson, M G; Meullenet, J-F; Dickson, J S; Holtzbauer, M J; Niebuhr, S E; Davis, B

2010-09-01

Contamination of poultry with pathogenic bacteria contributes to human foodborne disease, causes damage to industry brand names, and has a significant economic impact on the food industry in the form of both damage to industry brand names and losses associated with recalls. Irradiation is a safe and effective means of decontaminating poultry products, but the maximum dose strengths allowed negatively impact poultry sensory quality characteristics. The 1st objective of this study was to investigate the potential interactive inhibitory effects of natural antimicrobials as components of a vacuum-marination in addition to various dose levels of irradiation. Tartaric acid (TA) at 2 levels and grape seed (GS) and green tea (GT) extracts were combined, vacuum-infused into chicken breast fillets, and irradiated at 1, 2, and 3 kGy by electron beam irradiation. The 2nd objective was to use a consumer test group to evaluate TA and plant extract infusion into chicken breast fillets with and without irradiation at 2 kGy on overall impression, flavor, texture, appearance, and tenderness. The results showed that samples vacuum-infused with TA at 37.5 and 75.0 mM and irradiated at 1 kGy significantly reduced Listeria monocytogenes (L.m.) levels by 2 and 3 log CFU/g compared to the control after 12 d of refrigerated storage. Vacuum-infusion of TA at 37.5 and 75.0 mM at 2 and 3 kGy irradiation, reduced L.m. to near nondetectable levels. The addition of TA and GS and GT to chicken breast fillets with and without irradiation did not significantly impact consumer preference, tenderness, appearance, or flavor. The addition of tartaric acid and natural plant extracts to chicken marinades could contribute to the prevention of L.m. contamination.

A vacuum spark ion source: High charge state metal ion beams

DOE Office of Scientific and Technical Information (OSTI.GOV)

Yushkov, G. Yu., E-mail: gyushkov@mail.ru; Nikolaev, A. G.; Frolova, V. P.

2016-02-15

High ion charge state is often important in ion beam physics, among other reasons for the very practical purpose that it leads to proportionately higher ion beam energy for fixed accelerating voltage. The ion charge state of metal ion beams can be increased by replacing a vacuum arc ion source by a vacuum spark ion source. Since the voltage between anode and cathode remains high in a spark discharge compared to the vacuum arc, higher metal ion charge states are generated which can then be extracted as an ion beam. The use of a spark of pulse duration less thanmore » 10 μs and with current up to 10 kA allows the production of ion beams with current of several amperes at a pulse repetition rate of up to 5 pps. We have demonstrated the formation of high charge state heavy ions (bismuth) of up to 15 + and a mean ion charge state of more than 10 +. The physics and techniques of our vacuum spark ion source are described.« less

Comment on "How the huge energy of quantum vacuum gravitates to drive the slow accelerating expansion of the Universe"

NASA Astrophysics Data System (ADS)

Mazzitelli, Francisco D.; Trombetta, Leonardo G.

2018-03-01

In a recent paper [Q. Wang, Z. Zhu, and W. G. Unruh, Phys. Rev. D 95, 103504 (2017), 10.1103/PhysRevD.95.103504] it was argued that, due to the fluctuations around its mean value, vacuum energy gravitates differently from what was previously assumed. As a consequence, the Universe would accelerate with a small Hubble expansion rate, solving the cosmological constant and dark energy problems. We point out here that the results depend on the type of cutoff used to evaluate the vacuum energy. In particular, they are not valid when one uses a covariant cutoff such that the zero-point energy density is positive definite.

A vacuum-operated pore-water extractor for estuarine and freshwater sediments

USGS Publications Warehouse

Winger, Parley V.; Lasier, Peter J.

1991-01-01

A vacuum-operated pore-water extractor for estuarine and freshwater sediments was developed and constructed from a fused-glass air stone attached with aquarium airline tubing to a 30 or 60 cc polypropylene syringe. Pore water is extracted by inserting the air stone into the sediment and creating a vacuum by retracting and bracing the syringe plunger. A hand-operated vacuum pump attached to a filtration flask was also evaluated as an alternative vacuum source. The volume and time to extract pore water varies with the number of devices and the sediment particle size. Extraction time is longer for fine sediments than for sandy sediments. Four liters of sediment generally yield between 500 and 1,500 mL of pore water. The sediment that surrounds and accumulates on the air stone acts as a filter, and, except for the first few milliliters, the collected pore water is clear. Because there is no exposure to air or avenue for escape, volatile compounds andin situ characteristics are retained in the extracted pore water.

Killing approximation for vacuum and thermal stress-energy tensor in static space-times

DOE Office of Scientific and Technical Information (OSTI.GOV)

Frolov, V.P.; Zel'nikov, A.I.

1987-05-15

The problem of the vacuum polarization of conformal massless fields in static space-times is considered. A tensor T/sub ..mu..//sub ..nu../ constructed from the curvature, the Killing vector, and their covariant derivatives is proposed which can be used to approximate the average value of the stress-energy tensor /sup ren/ in such spaces. It is shown that if (i) its trace T /sub epsilon//sup epsilon/ coincides with the trace anomaly /sup ren/, (ii) it satisfies the conservation law T/sup ..mu..//sup epsilon/ /sub ;//sub epsilon/ = 0, and (iii) it has the correct behavior under the scale transformations, then it is uniquely definedmore » up to a few arbitrary constants. These constants must be chosen to satisfy the boundary conditions. In the case of a static black hole in a vacuum these conditions single out the unique tensor T/sub ..mu..//sub ..nu../ which provides a good approximation for /sup ren/ in the Hartle-Hawking vacuum. The relation between this approach and the Page-Brown-Ottewill approach is discussed.« less

Quantum Field Energy Sensor based on the Casimir Effect

NASA Astrophysics Data System (ADS)

Ludwig, Thorsten

The Casimir effect converts vacuum fluctuations into a measurable force. Some new energy technologies aim to utilize these vacuum fluctuations in commonly used forms of energy like electricity or mechanical motion. In order to study these energy technologies it is helpful to have sensors for the energy density of vacuum fluctuations. In today's scientific instrumentation and scanning microscope technologies there are several common methods to measure sub-nano Newton forces. While the commercial atomic force microscopes (AFM) mostly work with silicon cantilevers, there are a large number of reports on the use of quartz tuning forks to get high-resolution force measurements or to create new force sensors. Both methods have certain advantages and disadvantages over the other. In this report the two methods are described and compared towards their usability for Casimir force measurements. Furthermore a design for a quantum field energy sensor based on the Casimir force measurement will be described. In addition some general considerations on extracting energy from vacuum fluctuations will be given.

Sonoluminescence Explained by the Standpoint of Coherent Quantum Vacuum Dynamics and its Prospects for Energy Production

NASA Astrophysics Data System (ADS)

Maxmilian Caligiuri, Luigi; Musha, Takaaki

Sonoluminescence, or its more frequently studied version known as Single Bubble Sonoluminescence, consisting in the emission of light by a collapsing bubble in water under ultrasounds, represents one of the most challenging and interesting phenomenon in theoretical physics. In fact, despite its relatively easy reproducibility in a simple laboratory, its understanding within the commonly accepted picture of condensed matter remained so far unsatisfactory. On the other hand, the possibility to control the physical process involved in sonoluminescence, representing a sort of nuclear fusion on small scale, could open unthinkable prospects of free energy production from water. Different explanations has been proposed during the past years considering, in various way, the photoemission to be related to electromagnetic Zero Point Field energy dynamics, by considering the bubble surface as a Casimir force boundary. More recently a model invoking Cherenkov radiation emission from superluminal photons generated in quantum vacuum has been successfully proposed. In this paper it will be shown that the same results can be more generally explained and quantitative obtained within a QED coherent dynamics of quantum vacuum, according to which the electromagnetic energy of the emitted photons would be related to the latent heat involved in the phase transition from water's vapor to liquid phase during the bubble collapse. The proposed approach could also suggest an explanation of a possible mechanism of generation of faster than light (FTL) photons required to start Cherenkov radiation as well as possible applications to energy production from quantum vacuum.

Quantum vacuum effects from boundaries of designer potentials

DOE Office of Scientific and Technical Information (OSTI.GOV)

Konopka, Tomasz

2009-04-15

Vacuum energy in quantum field theory, being the sum of zero-point energies of all field modes, is formally infinite but yet, after regularization or renormalization, can give rise to finite observable effects. One way of understanding how these effects arise is to compute the vacuum energy in an idealized system such as a large cavity divided into disjoint regions by pistons. In this paper, this type of calculation is carried out for situations where the potential affecting a field is not the same in all regions of the cavity. It is shown that the observable parts of the vacuum energymore » in such potentials do not fall off to zero as the region where the potential is nontrivial becomes large. This unusual behavior might be interesting for tests involving quantum vacuum effects and for studies on the relation between vacuum energy in quantum field theory and geometry.« less

EVALUATION OF MASS FLUX TO AND FROM GROUND WATER USING A VERTICAL FLUX MODEL (VFLUX): APPLICATION TO THE SOIL VACUUM EXTRACTION CLOSURE PROBLEM

EPA Science Inventory

Site closure for soil vacuum extraction (SVE) application typically requires attainment of specified soil concentration standards based on the premise that mass flux from the vadose zone to ground water not result in levels exceeding maximum contaminant levels (MCLSs). Unfortuna...

Electroweak vacuum instability and renormalized Higgs field vacuum fluctuations in the inflationary universe

NASA Astrophysics Data System (ADS)

Kohri, Kazunori; Matsui, Hiroki

2017-08-01

In this work, we investigated the electroweak vacuum instability during or after inflation. In the inflationary Universe, i.e., de Sitter space, the vacuum field fluctuations < δ phi 2 > enlarge in proportion to the Hubble scale H2. Therefore, the large inflationary vacuum fluctuations of the Higgs field < δ phi 2 > are potentially catastrophic to trigger the vacuum transition to the negative-energy Planck-scale vacuum state and cause an immediate collapse of the Universe. However, the vacuum field fluctuations < δ phi 2 >, i.e., the vacuum expectation values have an ultraviolet divergence, and therefore a renormalization is necessary to estimate the physical effects of the vacuum transition. Thus, in this paper, we revisit the electroweak vacuum instability from the perspective of quantum field theory (QFT) in curved space-time, and discuss the dynamical behavior of the homogeneous Higgs field phi determined by the effective potential V eff( phi ) in curved space-time and the renormalized vacuum fluctuations < δ phi 2 >ren via adiabatic regularization and point-splitting regularization. We simply suppose that the Higgs field only couples the gravity via the non-minimal Higgs-gravity coupling ξ(μ). In this scenario, the electroweak vacuum stability is inevitably threatened by the dynamical behavior of the homogeneous Higgs field phi, or the formations of AdS domains or bubbles unless the Hubble scale is small enough H< ΛI .

Nonperturbative vacuum polarization effects in two-dimensional supercritical Dirac-Coulomb system I. Vacuum charge density

NASA Astrophysics Data System (ADS)

Davydov, A.; Sveshnikov, K.; Voronina, Yu.

2018-01-01

Based on the original combination of analytical methods, computer algebra tools and numerical calculations, proposed recently in Refs. 1-3, the nonperturbative vacuum polarization effects in the 2+1D supercritical Dirac-Coulomb system with Z > Zcr,1 are explored. Both the vacuum charge density ρV P(r→) and vacuum energy ℰV P are considered. The main result of the work is that in the overcritical region ℰV P turns out to be a rapidly decreasing function ˜-ηeffZ3/R with ηeff > 0 and R being the size of the external Coulomb source. Due to a lot of details of calculation the whole work is divided into two parts I and II. In the present part I, we consider the evaluation and behavior of the vacuum density ρV P, which further is used in part II for evaluation of the vacuum energy, with emphasis on the renormalization, convergence of the partial expansion for ρV P and behavior of the integral induced charge QV P in the overcritical region.

REVIEWS OF TOPICAL PROBLEMS: Cosmic vacuum

NASA Astrophysics Data System (ADS)

Chernin, Artur D.

2001-11-01

Recent observational studies of distant supernovae have suggested the existence of cosmic vacuum whose energy density exceeds the total density of all the other energy components in the Universe. The vacuum produces the field of antigravity that causes the cosmological expansion to accelerate. It is this accelerated expansion that has been discovered in the observations. The discovery of cosmic vacuum radically changes our current understanding of the present state of the Universe. It also poses new challenges to both cosmology and fundamental physics. Why is the density of vacuum what it is? Why do the densities of the cosmic energy components differ in exact value but agree in order of magnitude? On the other hand, the discovery made at large cosmological distances of hundreds and thousands Mpc provides new insights into the dynamics of the nearby Universe, the motions of galaxies in the local volume of 10 - 20 Mpc where the cosmological expansion was originally discovered.

Vacuum stress energy density and its gravitational implications

NASA Astrophysics Data System (ADS)

Estrada, Ricardo; Fulling, Stephen A.; Kaplan, Lev; Kirsten, Klaus; Liu, Zhonghai; Milton, Kimball A.

2008-04-01

In nongravitational physics the local density of energy is often regarded as merely a bookkeeping device; only total energy has an experimental meaning—and it is only modulo a constant term. But in general relativity the local stress-energy tensor is the source term in Einstein's equation. In closed universes, and those with Kaluza-Klein dimensions, theoretical consistency demands that quantum vacuum energy should exist and have gravitational effects, although there are no boundary materials giving rise to that energy by van der Waals interactions. In the lab there are boundaries, and in general the energy density has a nonintegrable singularity as a boundary is approached (for idealized boundary conditions). As pointed out long ago by Candelas and Deutsch, in this situation there is doubt about the viability of the semiclassical Einstein equation. Our goal is to show that the divergences in the linearized Einstein equation can be renormalized to yield a plausible approximation to the finite theory that presumably exists for realistic boundary conditions. For a scalar field with Dirichlet or Neumann boundary conditions inside a rectangular parallelepiped, we have calculated by the method of images all components of the stress tensor, for all values of the conformal coupling parameter and an exponential ultraviolet cutoff parameter. The qualitative features of contributions from various classes of closed classical paths are noted. Then the Estrada-Kanwal distributional theory of asymptotics, particularly the moment expansion, is used to show that the linearized Einstein equation with the stress-energy near a plane boundary as source converges to a consistent theory when the cutoff is removed. This paper reports work in progress on a project combining researchers in Texas, Louisiana and Oklahoma. It is supported by NSF Grants PHY-0554849 and PHY-0554926.

Drying behaviour, effective diffusivity and energy of activation of olive leaves dried by microwave, vacuum and oven drying methods

NASA Astrophysics Data System (ADS)

Elhussein, Elaf Abdelillah Ali; Şahin, Selin

2018-07-01

Drying is the crucial food processing for bioactive components from plant materials before strating extraction in addition to preservation of raw plant materials during storage period. Olive leaves were dried by various methods such as microwave drying (MD), oven drying (OD) and vacuum drying (VD) at several temperature values in the present study. Mathematical models allow to develop, design and control the processes. 14 emprical equations were used to estimate the drying behaviour and the time required for drying. Convenience of the models were evaluated according to the correlation coefficient ( R 2 ), varience ( S 2 ) and root mean square deviation ( D RMS ). On the other hand, the effective diffusion coefficient and energy for activation were also calculated. Effects of the drying methods on the total phenolic (TPC), flavonoid (TFC) and oleuropein contents and free radical scavenging activity (FRSA) of the olive leaves were also investigated to take into considiration the quality of the dried product. MD has proved to be the fastest drying method having the highest effective diffusivity and the lowest activation energy with a more qualitive product.

Drying behaviour, effective diffusivity and energy of activation of olive leaves dried by microwave, vacuum and oven drying methods

NASA Astrophysics Data System (ADS)

Elhussein, Elaf Abdelillah Ali; Şahin, Selin

2018-01-01

Drying is the crucial food processing for bioactive components from plant materials before strating extraction in addition to preservation of raw plant materials during storage period. Olive leaves were dried by various methods such as microwave drying (MD), oven drying (OD) and vacuum drying (VD) at several temperature values in the present study. Mathematical models allow to develop, design and control the processes. 14 emprical equations were used to estimate the drying behaviour and the time required for drying. Convenience of the models were evaluated according to the correlation coefficient (R 2 ), varience (S 2 ) and root mean square deviation (D RMS ). On the other hand, the effective diffusion coefficient and energy for activation were also calculated. Effects of the drying methods on the total phenolic (TPC), flavonoid (TFC) and oleuropein contents and free radical scavenging activity (FRSA) of the olive leaves were also investigated to take into considiration the quality of the dried product. MD has proved to be the fastest drying method having the highest effective diffusivity and the lowest activation energy with a more qualitive product.

Electroweak vacuum instability and renormalized Higgs field vacuum fluctuations in the inflationary universe

DOE Office of Scientific and Technical Information (OSTI.GOV)

Kohri, Kazunori; Matsui, Hiroki, E-mail: kohri@post.kek.jp, E-mail: matshiro@post.kek.jp

In this work, we investigated the electroweak vacuum instability during or after inflation. In the inflationary Universe, i.e., de Sitter space, the vacuum field fluctuations < δ φ {sup 2} > enlarge in proportion to the Hubble scale H {sup 2}. Therefore, the large inflationary vacuum fluctuations of the Higgs field < δ φ {sup 2} > are potentially catastrophic to trigger the vacuum transition to the negative-energy Planck-scale vacuum state and cause an immediate collapse of the Universe. However, the vacuum field fluctuations < δ φ {sup 2} >, i.e., the vacuum expectation values have an ultraviolet divergence, andmore » therefore a renormalization is necessary to estimate the physical effects of the vacuum transition. Thus, in this paper, we revisit the electroweak vacuum instability from the perspective of quantum field theory (QFT) in curved space-time, and discuss the dynamical behavior of the homogeneous Higgs field φ determined by the effective potential V {sub eff}( φ ) in curved space-time and the renormalized vacuum fluctuations < δ φ {sup 2} >{sub ren} via adiabatic regularization and point-splitting regularization. We simply suppose that the Higgs field only couples the gravity via the non-minimal Higgs-gravity coupling ξ(μ). In this scenario, the electroweak vacuum stability is inevitably threatened by the dynamical behavior of the homogeneous Higgs field φ, or the formations of AdS domains or bubbles unless the Hubble scale is small enough H < Λ {sub I} .« less

Breakdown-Resistant RF Connectors for Vacuum

NASA Technical Reports Server (NTRS)

Caro, Edward R.; Bonazza, Walter J.

1987-01-01

Resilient inserts compensate for insulation shrinkage. Coaxial-cable connector for radio-frequency (RF) energy resists electrical breakdown in vacuum. Used on RF equipment in vacuum chambers as well as in spaceborne radar and communication gear.

Employment Trends in Energy Extraction.

ERIC Educational Resources Information Center

Greene, Richard

1981-01-01

Between 1973 and 1980, employment in the basic energy extraction industries--coal, oil, and natural gas--has risen by more than 91 percent. The Arab oil embargo and subsequent emphasis on development of domestic energy sources are responsible for this trend. (Author/SK)

Damage induced to DNA by low-energy (0-30 eV) electrons under vacuum and atmospheric conditions.

PubMed

Brun, Emilie; Cloutier, Pierre; Sicard-Roselli, Cécile; Fromm, Michel; Sanche, Léon

2009-07-23

In this study, we show that it is possible to obtain data on DNA damage induced by low-energy (0-30 eV) electrons under atmospheric conditions. Five monolayer films of plasmid DNA (3197 base pairs) deposited on glass and gold substrates are irradiated with 1.5 keV X-rays in ultrahigh vacuum and under atmospheric conditions. The total damage is analyzed by agarose gel electrophoresis. The damage produced on the glass substrate is attributed to energy absorption from X-rays, whereas that produced on the gold substrate arises from energy absorption from both the X-ray beam and secondary electrons emitted from the gold surface. By analysis of the energy of these secondary electrons, 96% are found to have energies below 30 eV with a distribution peaking at 1.4 eV. The differences in damage yields recorded with the gold and glass substrates is therefore essentially attributed to the interaction of low-energy electrons with DNA under vacuum and hydrated conditions. From these results, the G values for low-energy electrons are determined to be four and six strand breaks per 100 eV, respectively.

Dynamical dark energy: Scalar fields and running vacuum

NASA Astrophysics Data System (ADS)

Solà, Joan; Gómez-Valent, Adrià; de Cruz Pérez, Javier

2017-03-01

Recent analyses in the literature suggest that the concordance ΛCDM model with rigid cosmological term, Λ = const. may not be the best description of the cosmic acceleration. The class of “running vacuum models”, in which Λ = Λ(H) evolves with the Hubble rate, has been shown to fit the string of SNIa + BAO + H(z) + LSS + CMB data significantly better than the ΛCDM. Here, we provide further evidence on the time-evolving nature of the dark energy (DE) by fitting the same cosmological data in terms of scalar fields. As a representative model, we use the original Peebles and Ratra potential, V ∝ ϕ-α. We find clear signs of dynamical DE at ˜ 4σ c.l., thus reconfirming through a nontrivial scalar field approach the strong hints formerly found with other models and parametrizations.

Processing of extraterrestrial materials by high temperature vacuum vaporization

NASA Technical Reports Server (NTRS)

Grimley, R. T.; Lipschutz, M. E.

1983-01-01

It is noted that problems associated with the extraction and concentration of elements and commpounds important for the construction and operation of space habitats have received little attention. High temperature vacuum vaporization is considered a promising approach; this is a technique for which the space environment offers advantages in the form of low ambient pressures and temperatures and the possibility of sustained high temperatures via solar thermal energy. To establish and refine this new technology, experimental determinations must be made of the material release profiles as a function of temperature, of the release kinetics and chemical forms of material being transported, and of the various means of altering release kinetics. Trace element data determined by neutron activation analysis of meteorites heated to 1400 C in vacuum is summarized. The principal tool, high temperature spectrometry, is used to examine the vaporization thermodynamics and kinetics of major and minor elements from complex multicomponent extraterrestrial materials.

Extraction study on uranyl nitrate for energy applications

NASA Astrophysics Data System (ADS)

Giri, R.; Nath, G.

2017-07-01

Due to the ever-growing demand of energy nuclear reactor materials and the nuclear energy are now considered to be the most critical materials and source of energy for future era. Deposition of nuclear wastes in different industry, nuclear power sector are very much toxic in open environment which are hazardous to living being. There are different methods for extraction and reprocessing of these materials which are cost effective and tedious process. Ultrasonic assisted solvent extraction process is a most efficient and economical way for extraction of such type materials. The presence of third phase in mixing of extractants-diluent pair with aqueous phase imposes the problems in extraction of nuclear reactor materials. The appropriate solvent mixture in proper concentration is an important step in the solvent extraction process. Study of thermo-physical properties helps in selecting an optimum blend for extraction process. In the present work, the extraction of uranium with the binary mixture of Methyl Ethyl Ketone (MEK) and Kerosene was investigated and discussed with the variation of ultrasonic frequency for different temperatures. The result shows that the low frequency and low temperature is suitable environment for extraction. The extraction of uranium by this method is found to be a better result for extraction study in laboratory scale as well as industrial sector.

A fixed collector employing reversible vee-trough concentrator and a vacuum tube receiver for high temperature solar energy systems

NASA Technical Reports Server (NTRS)

Selcuk, M. K.

1976-01-01

A solar heat collection system employing non-tracking reflectors integrated with a fixed vacuum tube receiver which achieves modest year-round concentration (about 2) of the sunlight at low capital costs is discussed. The axis of the vee-trough reflector lies in a east-west direction and requires reversal of the reflector surfaces only twice a year without disturbing the receiver tubes and associated plumbing. It collects most of the diffuse flux. The vacuum tube receiver with selective absorber has no convection losses while radiation and conduction losses are minimal. Significant cost reductions are offered since the vee-trough can be fabricated from inexpensive polished or plastic reflector laminated sheet metal covering 2/3 of the collection area, and only about 1/3 of the area is covered with the more expensive vacuum tube receivers. Thermal and economic performance of the vee-trough vacuum tube system, year-round variation of the concentration factor, incident flux, useful heat per unit area at various operation temperatures and energy cost estimates are presented. The electrical energy cost is estimated to be 77 mills/kWh, and the system construction cost is estimated to be $1140/kWe.

Langmuir vacuum and superconductivity

DOE Office of Scientific and Technical Information (OSTI.GOV)

Veklenko, B. A.

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.

Modeling and prediction of extraction profile for microwave-assisted extraction based on absorbed microwave energy.

PubMed

Chan, Chung-Hung; Yusoff, Rozita; Ngoh, Gek-Cheng

2013-09-01

A modeling technique based on absorbed microwave energy was proposed to model microwave-assisted extraction (MAE) of antioxidant compounds from cocoa (Theobroma cacao L.) leaves. By adapting suitable extraction model at the basis of microwave energy absorbed during extraction, the model can be developed to predict extraction profile of MAE at various microwave irradiation power (100-600 W) and solvent loading (100-300 ml). Verification with experimental data confirmed that the prediction was accurate in capturing the extraction profile of MAE (R-square value greater than 0.87). Besides, the predicted yields from the model showed good agreement with the experimental results with less than 10% deviation observed. Furthermore, suitable extraction times to ensure high extraction yield at various MAE conditions can be estimated based on absorbed microwave energy. The estimation is feasible as more than 85% of active compounds can be extracted when compared with the conventional extraction technique. Copyright © 2013 Elsevier Ltd. All rights reserved.

The trace anomaly and dynamical vacuum energy in cosmology

DOE Office of Scientific and Technical Information (OSTI.GOV)

Mottola, Emil

2010-04-30

The trace anomaly of conformal matter implies the existence of massless scalar poles in physical amplitudes involving the stress-energy tensor. These poles may be described by a local effective action with massless scalar fields, which couple to classical sources, contribute to gravitational scattering processes, and can have long range gravitational effects at macroscopic scales. In an effective field theory approach, the effective action of the anomaly is an infrared relevant term that should be added to the Einstein-Hilbert action of classical General Relativity to take account of macroscopic quantum effects. The additional scalar degrees of freedom contained in this effectivemore » action may be understood as responsible for both the Casimir effect in flat spacetime and large quantum backreaction effects at the horizon scale of cosmological spacetimes. These effects of the trace anomaly imply that the cosmological vacuum energy is dynamical, and its value depends on macroscopic boundary conditions at the cosmological horizon scale, rather than sensitivity to the extreme ultraviolet Planck scale.« less

Capacitive Energy Extraction by Few-Layer Graphene Electrodes

DOE Office of Scientific and Technical Information (OSTI.GOV)

Lian, Cheng; Zhan, Cheng; Jiang, De-en

Capacitive double-layer expansion is a promising technology to harvest energy arising from the salinity difference between freshwater and seawater. Its optimal performance requires a careful selection of the operation potentials and electrode materials. While carbonaceous materials such as graphene and various forms of activated carbons are routinely used as the electrodes, there is little knowledge on how the quantum capacitance and the electric double-layer (EDL) capacitance, which are on the same order of magnitude, affect the capacitive performance. Toward understanding that from a theoretical perspective, here we study the capacitive energy extraction with graphene electrodes as a function of themore » number of graphene layers. The classical density functional theory is joined with the electronic density functional theory to obtain the EDL and the quantum capacitance, respectively. The theoretical results show that the quantum capacitance contribution plays a dominant role in extracting energy using the single-layer graphene, but its effect diminishes as the number of graphene layers increases. The overall extracted energy is dominated by the EDL contribution beyond about four graphene layers. Electrodes with more graphene layers are able to extract more energy at low charging potential. Here, because many porous carbons have nanopores with stacked graphene layers, our theoretical predictions are useful to identify optimal operation parameters for capacitive energy extraction with porous electrodes of different wall thickness.« less

Capacitive Energy Extraction by Few-Layer Graphene Electrodes

DOE PAGES

Lian, Cheng; Zhan, Cheng; Jiang, De-en; ...

2017-06-09

Capacitive double-layer expansion is a promising technology to harvest energy arising from the salinity difference between freshwater and seawater. Its optimal performance requires a careful selection of the operation potentials and electrode materials. While carbonaceous materials such as graphene and various forms of activated carbons are routinely used as the electrodes, there is little knowledge on how the quantum capacitance and the electric double-layer (EDL) capacitance, which are on the same order of magnitude, affect the capacitive performance. Toward understanding that from a theoretical perspective, here we study the capacitive energy extraction with graphene electrodes as a function of themore » number of graphene layers. The classical density functional theory is joined with the electronic density functional theory to obtain the EDL and the quantum capacitance, respectively. The theoretical results show that the quantum capacitance contribution plays a dominant role in extracting energy using the single-layer graphene, but its effect diminishes as the number of graphene layers increases. The overall extracted energy is dominated by the EDL contribution beyond about four graphene layers. Electrodes with more graphene layers are able to extract more energy at low charging potential. Here, because many porous carbons have nanopores with stacked graphene layers, our theoretical predictions are useful to identify optimal operation parameters for capacitive energy extraction with porous electrodes of different wall thickness.« less

Vacuum fluctuations of the supersymmetric field in curved background

NASA Astrophysics Data System (ADS)

Bilić, Neven; Domazet, Silvije; Guberina, Branko

2012-01-01

We study a supersymmetric model in curved background spacetime. We calculate the effective action and the vacuum expectation value of the energy momentum tensor using a covariant regularization procedure. A soft supersymmetry breaking induces a nonzero contribution to the vacuum energy density and pressure. Assuming the presence of a cosmic fluid in addition to the vacuum fluctuations of the supersymmetric field an effective equation of state is derived in a self-consistent approach at one loop order. The net effect of the vacuum fluctuations of the supersymmetric fields in the leading adiabatic order is a renormalization of the Newton and cosmological constants.

Indian Vacuum Society: The Indian Vacuum Society

NASA Astrophysics Data System (ADS)

Saha, T. K.

2008-03-01

has instituted the `IVS- Professor D Y Phadke Memorial Prize' in memory of our founder president, the late Professor D Y Phadke at the University of Mumbai. The prize is given every year to the student ranked top in the MSc (PHY.) examination conducted by the university. The IVS Kolkata Chapter has established the Dr A S Divatia Memorial Trust with the objective of organizing the Dr A S Divatia Memorial Lecture and a seminar once a year and to set up a vacuum testing and calibration facility. IVS has instituted an award in memory of the late Shri C Ambasankaran, its past president and pioneer of vacuum technology in India. This award is given to one of the best papers presented in the national symposium conducted by IVS. One more best paper award `Smt. Shakuntalabai Vyawahare Memorial Prize' is established from a donation given by Shri Mohan R Vyawahare, a life member and a present EC member of the society, in memory of his mother. During the symposia, IVS felicitates two of its members, one from Industry and one from an R & D Institution for their lifetime contribution to vacuum science and technology. Dr A K Gupta, Ex BARC, Ex Generla Manager, IBP, Head, Energy Group, Shapoorji Pallonji & Co Ltd (Industry), and Dr S R Gowariker, Ex BARC, Ex Director, CSIO, Chandigarh, Director, Tolani Education Foundation (R & D) are being honoured this year. T K Saha Geneneral Secretary, IVS

Double Higgs mechanisms, supermassive stable particles and the vacuum energy

NASA Astrophysics Data System (ADS)

Santillán, Osvaldo P.; Gabbanelli, Luciano

2016-07-01

In the present work, a hidden scenario which cast a long-lived superheavy particle A0 and simultaneously an extremely light particle a with mass ma ˜ 10-32-10-33 eV is presented. The potential energy V (a) of the particle a models the vacuum energy density of the universe ρc ≃ 10-47GeV4. On the other hand, the A0 particle may act as superheavy dark matter at present times and the products of its decay may be observed in high energy cosmic ray events. The hidden sector proposed here include light fermions with masses near the neutrino mass mν ˜ 10-2 eV and superheavy ones with masses of the order of the GUT scale, interacting through a hidden SU(2)L interaction which also affects the ordinary sector. The construction of such combined scenario is nontrivial since the presence of light particles may spoil the stability of the heavy particle A0. However, double Higgs mechanisms may be helpful for overcoming this problem. In this context, the stability of the superheavy particle A0 is ensured due to chiral symmetry arguments elaborated in the text.

Batteries for efficient energy extraction from a water salinity difference.

PubMed

La Mantia, Fabio; Pasta, Mauro; Deshazer, Heather D; Logan, Bruce E; Cui, Yi

2011-04-13

The salinity difference between seawater and river water is a renewable source of enormous entropic energy, but extracting it efficiently as a form of useful energy remains a challenge. Here we demonstrate a device called "mixing entropy battery", which can extract and store it as useful electrochemical energy. The battery, containing a Na(2-x)Mn(5)O(10) nanorod electrode, was shown to extract energy from real seawater and river water and can be applied to a variety of salt waters. We demonstrated energy extraction efficiencies of up to 74%. Considering the flow rate of river water into oceans as the limiting factor, the renewable energy production could potentially reach 2 TW, or ∼13% of the current world energy consumption. The mixing entropy battery is simple to fabricate and could contribute significantly to renewable energy in the future.

Electron stripping processes of H⁻ ion beam in the 80 kV high voltage extraction column and low energy beam transport line at LANSCE.

PubMed

Draganic, I N

2016-02-01

Basic vacuum calculations were performed for various operating conditions of the Los Alamos National Neutron Science H(-) Cockcroft-Walton (CW) injector and the Ion Source Test Stand (ISTS). The vacuum pressure was estimated for both the CW and ISTS at five different points: (1) inside the H(-) ion source, (2) in front of the Pierce electrode, (3) at the extraction electrode, (4) at the column electrode, and (5) at the ground electrode. A static vacuum analysis of residual gases and the working hydrogen gas was completed for the normal ion source working regime. Gas density and partial pressure were estimated for the injected hydrogen gas. The attenuation of H(-) beam current and generation of electron current in the high voltage acceleration columns and low energy beam transport lines were calculated. The interaction of H(-) ions on molecular hydrogen (H2) is discussed as a dominant collision process in describing electron stripping rates. These results are used to estimate the observed increase in the ratio of electrons to H(-) ion beam in the ISTS beam transport line.

Derivation of the cut-off length from the quantum quadratic enhancement of a mass in vacuum energy constant Lambda

NASA Astrophysics Data System (ADS)

Fukushima, Kimichika; Sato, Hikaru

2018-04-01

Ultraviolet self-interaction energies in field theory sometimes contain meaningful physical quantities. The self-energies in such as classical electrodynamics are usually subtracted from the rest mass. For the consistent treatment of energies as sources of curvature in the Einstein field equations, this study includes these subtracted self-energies into vacuum energy expressed by the constant Lambda (used in such as Lambda-CDM). In this study, the self-energies in electrodynamics and macroscopic classical Einstein field equations are examined, using the formalisms with the ultraviolet cut-off scheme. One of the cut-off formalisms is the field theory in terms of the step-function-type basis functions, developed by the present authors. The other is a continuum theory of a fundamental particle with the same cut-off length. Based on the effectiveness of the continuum theory with the cut-off length shown in the examination, the dominant self-energy is the quadratic term of the Higgs field at a quantum level (classical self-energies are reduced to logarithmic forms by quantum corrections). The cut-off length is then determined to reproduce today's tiny value of Lambda for vacuum energy. Additionally, a field with nonperiodic vanishing boundary conditions is treated, showing that the field has no zero-point energy.

Pauli-Zeldovich cancellation of the vacuum energy divergences, auxiliary fields and supersymmetry

NASA Astrophysics Data System (ADS)

Kamenshchik, Alexander Yu.; Starobinsky, Alexei A.; Tronconi, Alessandro; Vardanyan, Tereza; Venturi, Giovanni

2018-03-01

We have considered the Pauli-Zeldovich mechanism for the cancellation of the ultraviolet divergences in vacuum energy. This mechanism arises because bosons and fermions give contributions of the opposite signs. In contrast with the preceding papers devoted to this topic wherein mainly free fields were studied, here we have taken their interactions into account to the lowest order of perturbation theory. We have constructed some simple toy models having particles with spin 0 and spin 1 / 2, where masses of the particles are equal while the interactions can be quite non-trivial.

Advanced Photon Source accelerator ultrahigh vacuum guide

DOE Office of Scientific and Technical Information (OSTI.GOV)

Liu, C.; Noonan, J.

1994-03-01

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.

In-vacuum exposure shutter

DOEpatents

Johnson, Terry A.; Replogle, William C.; Bernardez, Luis J.

2004-06-01

An in-vacuum radiation exposure shutter device can be employed to regulate a large footprint light beam. The shutter device includes (a) a source of radiation that generates an energy beam; (2) a shutter that includes (i) a frame defining an aperture toward which the energy beam is directed and (ii) a plurality of blades that are secured to the frame; and (3) device that rotates the shutter to cause the plurality of blades to intercept or allow the energy beam to travel through the aperture. Each blade can have a substantially planar surface and the plurality of blades are secured to the frame such that the planar surfaces of the plurality of blades are substantially parallel to each other. The shutter device is particularly suited for operation in a vacuum environment and can achieve shuttering speeds from about 0.1 second to 0.001 second or faster.

Determination of diffusion coefficients of hydrogen and deuterium in Zr-2.5%Nb pressure tube material using hot vacuum extraction-quadrupole mass spectrometry

NASA Astrophysics Data System (ADS)

Shrivastava, Komal Chandra; Kulkarni, A. S.; Ramanjaneyulu, P. S.; Sunil, Saurav; Saxena, M. K.; Singh, R. N.; Tomar, B. S.; Ramakumar, K. L.

2015-06-01

The diffusion coefficients of hydrogen and deuterium in Zr-2.5%Nb alloy were measured in the temperature range 523 to 673 K, employing hot vacuum extraction-quadrupole mass spectrometry (HVE-QMS). One end of the Zr-2.5%Nb alloy specimens was charged electrolytically with the desired hydrogen isotope. After annealing at different temperatures for a predetermined time, the specimens were cut into thin slices, which were analyzed for their H2/D2 content using the HVE-QMS technique. The depth profile data were fitted into the equation representing the solution of Fick's second law of diffusion. The activation energy of hydrogen/deuterium diffusion was obtained from the Arrhenius relation between the diffusion coefficient and temperature. The temperature dependent diffusion coefficient can be represented as DH = 1.41 × 10-7 exp(-36,000/RT) and DD = 6.16 × 10-8 exp(-35,262/RT) for hydrogen and deuterium, respectively.

Dyonic Flux Tube Structure of Nonperturbative QCD Vacuum

NASA Astrophysics Data System (ADS)

Chandola, H. C.; Pandey, H. C.

We study the flux tube structure of the nonperturbative QCD vacuum in terms of its dyonic excitations by using an infrared effective Lagrangian and show that the dyonic condensation of QCD vacuum has a close connection with the process of color confinement. Using the fiber bundle formulation of QCD, the magnetic symmetry condition is presented in a gauge covariant form and the gauge potential has been constructed in terms of the magnetic vectors on global sections. The dynamical breaking of the magnetic symmetry has been shown to lead the dyonic condensation of QCD vacuum in the infrared energy sector. Deriving the asymptotic solutions of the field equations in the dynamically broken phase, the dyonic flux tube structure of QCD vacuum is explored which has been shown to lead the confinement parameters in terms of the vector and scalar mass modes of the condensed vacuum. Evaluating the charge quantum numbers and energy associated with the dyonic flux tube solutions, the effect of electric excitation of monopole is analyzed using the Regge slope parameter (as an input parameter) and an enhancement in the dyonic pair correlations and the confining properties of QCD vacuum in its dyonically condensed mode has been demonstrated.

Characterization of the Heat Extraction Capability of a Compliant, Sliding, Thermal Interface for Use in a High Temperature, Vacuum, Microgravity Furnace

NASA Technical Reports Server (NTRS)

Bellomy-Ezell, Jenny; Farmer, Jeff; Breeding, Shawn; Spivey, Reggie

2001-01-01

A compliant, thermal interface material is tested to evaluate its thermal behavior at elevated temperatures, in vacuum conditions, and under varying levels of compression. Preliminary results indicate that the thermal performance of this polymer fiber-based, felt-like material is sufficient to meet thermal extraction requirements for the Quench Module Insert, a Bridgman furnace for microgravity material science investigation. This paper discusses testing and modeling approaches employed, gives of a status of characterization activities and provides preliminary test results.

Enhancing radiative energy transfer through thermal extraction

NASA Astrophysics Data System (ADS)

Tan, Yixuan; Liu, Baoan; Shen, Sheng; Yu, Zongfu

2016-06-01

Thermal radiation plays an increasingly important role in many emerging energy technologies, such as thermophotovoltaics, passive radiative cooling and wearable cooling clothes [1]. One of the fundamental constraints in thermal radiation is the Stefan-Boltzmann law, which limits the maximum power of far-field radiation to P0 = σT4S, where σ is the Boltzmann constant, S and T are the area and the temperature of the emitter, respectively (Fig. 1a). In order to overcome this limit, it has been shown that near-field radiations could have an energy density that is orders of magnitude greater than the Stefan-Boltzmann law [2-7]. Unfortunately, such near-field radiation transfer is spatially confined and cannot carry radiative heat to the far field. Recently, a new concept of thermal extraction was proposed [8] to enhance far-field thermal emission, which, conceptually, operates on a principle similar to oil immersion lenses and light extraction in light-emitting diodes using solid immersion lens to increase light output [62].Thermal extraction allows a blackbody to radiate more energy to the far field than the apparent limit of the Stefan-Boltzmann law without breaking the second law of thermodynamics. Thermal extraction works by using a specially designed thermal extractor to convert and guide the near-field energy to the far field, as shown in Fig. 1b. The same blackbody as shown in Fig. 1a is placed closely below the thermal extractor with a spacing smaller than the thermal wavelength. The near-field coupling transfers radiative energy with a density greater than σT4. The thermal extractor, made from transparent and high-index or structured materials, does not emit or absorb any radiation. It transforms the near-field energy and sends it toward the far field. As a result, the total amount of far-field radiative heat dissipated by the same blackbody is greatly enhanced above SσT4, where S is the area of the emitter. This paper will review the progress in thermal

Extracting black-hole rotational energy: The generalized Penrose process

NASA Astrophysics Data System (ADS)

Lasota, J.-P.; Gourgoulhon, E.; Abramowicz, M.; Tchekhovskoy, A.; Narayan, R.

2014-01-01

In the case involving particles, the necessary and sufficient condition for the Penrose process to extract energy from a rotating black hole is absorption of particles with negative energies and angular momenta. No torque at the black-hole horizon occurs. In this article we consider the case of arbitrary fields or matter described by an unspecified, general energy-momentum tensor Tμν and show that the necessary and sufficient condition for extraction of a black hole's rotational energy is analogous to that in the mechanical Penrose process: absorption of negative energy and negative angular momentum. We also show that a necessary condition for the Penrose process to occur is for the Noether current (the conserved energy-momentum density vector) to be spacelike or past directed (timelike or null) on some part of the horizon. In the particle case, our general criterion for the occurrence of a Penrose process reproduces the standard result. In the case of relativistic jet-producing "magnetically arrested disks," we show that the negative energy and angular-momentum absorption condition is obeyed when the Blandford-Znajek mechanism is at work, and hence the high energy extraction efficiency up to ˜300% found in recent numerical simulations of such accretion flows results from tapping the black hole's rotational energy through the Penrose process. We show how black-hole rotational energy extraction works in this case by describing the Penrose process in terms of the Noether current.

Dynamical emergence of the Universe into the false vacuum

NASA Astrophysics Data System (ADS)

Rafelski, Johann; Birrell, Jeremiah

2015-11-01

We study how the hot Universe evolves and acquires the prevailing vacuum state, demonstrating that in specific conditions which are believed to apply, the Universe becomes frozen into the state with the smallest value of Higgs vacuum field v=langle hrangle, even if this is not the state of lowest energy. This supports the false vacuum dark energy Λ-model. Under several likely hypotheses we determine the temperature in the evolution of the Universe at which two vacuua v1, v2 can swap between being true and false. We evaluate the dynamical surface pressure on domain walls between low and high mass vaccua due to the presence of matter and show that the low mass state remains the preferred vacuum of the Universe.

[Dual chamber safety vacuum--initial experiences with a new suction cup].

PubMed

Korell, M; King, S; Hepp, H

1994-06-01

The main problem with vacuum extraction methods, alongside the cephalhaematoma produced, is the premature separation of the suction cup under traction, since the resulting sudden change in pressure can lead to severe intra-cerebral damage to the child. To reduce the risk of vaginal operative delivery, a new double-chamber safety vacuum extractor has been developed by Hepp/King. The basic feature of this instrument is an additional chamber with a thin overlapping area, which surrounds the actual suction cup and serves as a safety vacuum. If the suction cup starts to slip, the external vacuum is released and sounds an alarm. In addition, the inner vacuum has been designed to be convex and to reduce the volume of scalp, which is sucked into the vacuum, thus reducing the size of the cephalhaematoma produced. First experiences in clinical use demonstrated the reliability of the early warning signal, if the direction of traction is false or the applied traction is too strong. The inner vacuum remains constant at 0.8 atu, so that with care, the extraction can continue without interruption. We have used the new instrument in 18 deliveries. In 15 cases, the indication was failure to progress into the second stage of labour; in one case history of retinal detachment and in two cases signs of foetal asphyxia. In all cases, the child was delivered following one or two contractions with traction, without losing the vacuum. The average weight of the newborn was 3566 g. As expected, the cephalohaematoma produced was very much smaller than usual. Further clinical trials are necessary before the value of this new instrument can be assessed.

Dark matter as an effect of the quantum vacuum

NASA Astrophysics Data System (ADS)

Santos, Emilio

2018-04-01

The interaction between the quantum vacuum and a weak gravitational field is calculated for the vacuum fields of quantum electrodynamics. The result shows that the vacuum state is modified by the gravitational field, giving rise to a nonzero interaction energy. This suggests a model that fits in the main properties of the hypothetical dark matter in galactic haloes.

Cosmic vacuum and galaxy formation

NASA Astrophysics Data System (ADS)

Chernin, A. D.

2006-04-01

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/[(8π/3)ρV]}1/3, where M is the mass of a given over-density and ρV 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.

[Noncollagen bone proteins use in the composition of osteoplactic material Gapkol modified by vacuum].

PubMed

Volozhin, A I; Grigor'ian, A S; Desiatnichenko, K S; Ozhelevskaia, S A; Doktorov, A A; Kurdiumov, S G; Fionova, E V; Gurin, A N; Karakov, K G

2008-01-01

In rat experiments the ability of noncollagen bone proteins (NCBP) in the composition of osteoplactic modified material Gapkol (not tanned in formalin and subjected to vacuum extraction) to increase bone reparation in comparison with traditional Gapkol was studied. Quantitative evaluation was performed on rat parietal bone and qualitative evaluation was performed on rat mandible. It was shown that Gapkol with NCBP (not tanned in formalin and subjected to vacuum extraction) increased reparative osteogenesis.

Modeling In-stream Tidal Energy Extraction and Its Potential Environmental Impacts

DOE Office of Scientific and Technical Information (OSTI.GOV)

Yang, Zhaoqing; Wang, Taiping; Copping, Andrea

In recent years, there has been growing interest in harnessing in-stream tidal energy in response to concerns of increasing energy demand and to mitigate climate change impacts. While many studies have been conducted to assess and map tidal energy resources, efforts for quantifying the associated potential environmental impacts have been limited. This paper presents the development of a tidal turbine module within a three-dimensional unstructured-grid coastal ocean model and its application for assessing the potential environmental impacts associated with tidal energy extraction. The model is used to investigate in-stream tidal energy extraction and associated impacts on estuarine hydrodynamic and biologicalmore » processes in a tidally dominant estuary. A series of numerical experiments with varying numbers and configurations of turbines installed in an idealized estuary were carried out to assess the changes in the hydrodynamics and biological processes due to tidal energy extraction. Model results indicated that a large number of turbines are required to extract the maximum tidal energy and cause significant reduction of the volume flux. Preliminary model results also indicate that extraction of tidal energy increases vertical mixing and decreases flushing rate in a stratified estuary. The tidal turbine model was applied to simulate tidal energy extraction in Puget Sound, a large fjord-like estuary in the Pacific Northwest coast.« less

Deterministic Impulsive Vacuum Foundations for Quantum-Mechanical Wavefunctions

NASA Astrophysics Data System (ADS)

Valentine, John S.

2013-09-01

By assuming that a fermion de-constitutes immediately at source, that its constituents, as bosons, propagate uniformly as scalar vacuum terms with phase (radial) symmetry, and that fermions are unique solutions for specific phase conditions, we find a model that self-quantizes matter from continuous waves, unifying bosons and fermion ontologies in a single basis, in a constitution-invariant process. Vacuum energy has a wavefunction context, as a mass-energy term that enables wave collapse and increases its amplitude, with gravitational field as the gradient of the flux density. Gravitational and charge-based force effects emerge as statistics without special treatment. Confinement, entanglement, vacuum statistics, forces, and wavefunction terms emerge from the model's deterministic foundations.

Turbine Design for Energy Extraction from Dust Devils

NASA Astrophysics Data System (ADS)

Malaya, Nicholas; Moser, Robert

2016-11-01

Columnar vortices ("Dust-Devils") arise naturally in the atmosphere, over a wide range of scales in many different locations across the Earth, as well as on Mars. A new energy harvesting approach makes use of this ubiquitous process by creating and anchoring the vortices artificially and extracting energy from them. However, any analysis of the power that can be extracted is complicated by the presence of considerable vertical and azimuthal flow in the vortex, and so the design considerations are different from those for a classical wind turbine. This talk presents a modeling approach to estimate the upper limit on the power that could be extracted from such a flow. This method is based on the actuator disk model common to turbine design, but with generalized drag polars permitting exploration of a broader design space. This model can be fully coupled to the flow, which ensures the results do not violate any Betz-like considerations that might similarly arise in an analysis of frozen flow fields. The results of this model demonstrate a limit on how much of the energy can be extracted before disrupting the flow so greatly that the vortex cannot be maintained. This work supported by the Department of Energy [ARPA-E] un- der Award Number [DE-FOA-0000670].

Dynamical emergence of the Universe into the false vacuum

DOE Office of Scientific and Technical Information (OSTI.GOV)

Rafelski, Johann; Birrell, Jeremiah, E-mail: rafelski@physics.arizona.edu, E-mail: jbirrell@email.arizona.edu

We study how the hot Universe evolves and acquires the prevailing vacuum state, demonstrating that in specific conditions which are believed to apply, the Universe becomes frozen into the state with the smallest value of Higgs vacuum field v=( h), even if this is not the state of lowest energy. This supports the false vacuum dark energy Λ-model. Under several likely hypotheses we determine the temperature in the evolution of the Universe at which two vacuua v{sub 1}, v{sub 2} can swap between being true and false. We evaluate the dynamical surface pressure on domain walls between low and high mass vaccuamore » due to the presence of matter and show that the low mass state remains the preferred vacuum of the Universe.« less

Vacuum force

NASA Astrophysics Data System (ADS)

Han, Yongquan

2015-03-01

To study on vacuum force, we must clear what is vacuum, vacuum is a space do not have any air and also ray. There is not exist an absolute the vacuum of space. The vacuum of space is relative, so that the vacuum force is relative. There is a certain that vacuum vacuum space exists. In fact, the vacuum space is relative, if the two spaces compared to the existence of relative vacuum, there must exist a vacuum force, and the direction of the vacuum force point to the vacuum region. Any object rotates and radiates. Rotate bend radiate- centripetal, gravity produced, relative gravity; non gravity is the vacuum force. Gravity is centripetal, is a trend that the objects who attracted wants to Centripetal, or have been do Centripetal movement. Any object moves, so gravity makes the object curve movement, that is to say, the radiation range curve movement must be in the gravitational objects, gravity must be existed in non vacuum region, and make the object who is in the region of do curve movement (for example: The earth moves around the sun), or final attracted in the form gravitational objects, and keep relatively static with attract object. (for example: objects on the earth moves but can't reach the first cosmic speed).

Random numbers from vacuum fluctuations

DOE Office of Scientific and Technical Information (OSTI.GOV)

Shi, Yicheng; Kurtsiefer, Christian, E-mail: christian.kurtsiefer@gmail.com; Center for Quantum Technologies, National University of Singapore, 3 Science Drive 2, Singapore 117543

2016-07-25

We implement a quantum random number generator based on a balanced homodyne measurement of vacuum fluctuations of the electromagnetic field. The digitized signal is directly processed with a fast randomness extraction scheme based on a linear feedback shift register. The random bit stream is continuously read in a computer at a rate of about 480 Mbit/s and passes an extended test suite for random numbers.

Running vacuum cosmological models: linear scalar perturbations

NASA Astrophysics Data System (ADS)

Perico, E. L. D.; Tamayo, D. A.

2017-08-01

In cosmology, phenomenologically motivated expressions for running vacuum are commonly parameterized as linear functions typically denoted by Λ(H2) or Λ(R). Such models assume an equation of state for the vacuum given by bar PΛ = - bar rhoΛ, relating its background pressure bar PΛ with its mean energy density bar rhoΛ ≡ Λ/8πG. This equation of state suggests that the vacuum dynamics is due to an interaction with the matter content of the universe. Most of the approaches studying the observational impact of these models only consider the interaction between the vacuum and the transient dominant matter component of the universe. We extend such models by assuming that the running vacuum is the sum of independent contributions, namely bar rhoΛ = Σibar rhoΛi. Each Λ i vacuum component is associated and interacting with one of the i matter components in both the background and perturbation levels. We derive the evolution equations for the linear scalar vacuum and matter perturbations in those two scenarios, and identify the running vacuum imprints on the cosmic microwave background anisotropies as well as on the matter power spectrum. In the Λ(H2) scenario the vacuum is coupled with every matter component, whereas the Λ(R) description only leads to a coupling between vacuum and non-relativistic matter, producing different effects on the matter power spectrum.

Optimal Energy Extraction From a Hot Water Geothermal Reservoir

NASA Astrophysics Data System (ADS)

Golabi, Kamal; Scherer, Charles R.; Tsang, Chin Fu; Mozumder, Sashi

1981-01-01

An analytical decision model is presented for determining optimal energy extraction rates from hot water geothermal reservoirs when cooled brine is reinjected into the hot water aquifer. This applied economic management model computes the optimal fluid pumping rate and reinjection temperature and the project (reservoir) life consistent with maximum present worth of the net revenues from sales of energy for space heating. The real value of product energy is assumed to increase with time, as is the cost of energy used in pumping the aquifer. The economic model is implemented by using a hydrothermal model that relates hydraulic pumping rate to the quality (temperature) of remaining heat energy in the aquifer. The results of a numerical application to space heating show that profit-maximizing extraction rate increases with interest (discount) rate and decreases as the rate of rise of real energy value increases. The economic life of the reservoir generally varies inversely with extraction rate. Results were shown to be sensitive to permeability, initial equilibrium temperature, well cost, and well life.

Clinical impact of the disposable ventouse iCup® versus a metallic vacuum cup: a multicenter randomized controlled trial.

PubMed

Equy, Véronique; David-Tchouda, Sandra; Dreyfus, Michel; Riethmuller, Didier; Vendittelli, Françoise; Cabaud, Victoire; Langer, Bruno; Margier, Jennifer; Bosson, Jean-Luc; Schaal, Jean-Patrick

2015-12-15

Assisted vaginal delivery by vacuum extraction is frequent. Metallic resterilizible metallic vacuum cups have been routinely used in France. In the last few years a new disposable semi-soft vacuum extraction cup, the iCup, has been introduced. Our objective was to compare maternal and new-born outcomes between this disposable cup and the commonly used Drapier-Faure metallic cup. This was a multicenter prospective randomized controlled open clinical trial performed in the maternity units of five university hospitals and one community hospital in France from October 2009 to February 2013. We included consecutive eligible women with a singleton gestation of at least 37 weeks who required vacuum assisted delivery. Women were randomized to vacuum extraction using the iCup or usual Drapier-Faure metallic cup. The primary outcome was a composite criterion including both the risk of cup dysfunction and the most frequent maternal and neonatal harms: the use of other instruments after attempted vacuum extraction, caesarean section after attempted vacuum extraction, three detachments of the cup, caput succedaneum, cephalohaematoma, episiotomy and perineal tears. 335 women were randomized to the disposable cup and 333 to extraction using the metallic cup. There was no significant difference between the two groups for the primary outcome. However, failed instrumental delivery was more frequent in the disposable cup group, mainly due to detachment: 35.6 % vs 7.1 %, p < 0.0001. Conversely, perineal tears were more frequent in the metallic cup group, especially third or fourth grade perineal tears: 1.7 % versus 5.0 %, p = 0.003. There were no significant differences between the two groups concerning post-partum haemorrhage, transfer to a neonatal intensive care unit (NICU) or serious adverse events. While the disposable cup had more detachments and extraction failures than the standard metallic cup, this innovative disposable device had the advantage of fewer perineal

Microwave-assisted extraction performed in low temperature and in vacuo for the extraction of labile compounds in food samples.

PubMed

Xiao, Xiaohua; Song, Wei; Wang, Jiayue; Li, Gongke

2012-01-27

In this study, low temperature vacuum microwave-assisted extraction, which simultaneous performed microwave-assisted extraction (MAE) in low temperature and in vacuo environment, was proposed. The influencing parameters including solid/liquid ratio, extraction temperature, extraction time, degree of vacuum and microwave power were discussed. The predominance of low temperature vacuum microwave-assisted extraction was investigated by comparing the extraction yields of vitamin C, β-carotene, aloin A and astaxanthin in different foods with that in MAE and solvent extraction, and 5.2-243% increments were obtained. On the other hand, the chemical kinetics of vitamin C and aloin A, which composed two different steps including the extraction step of analyte transferred from matrix into solvent and the decomposition step of analyte degraded in the extraction solvent, were proposed. All of the decomposition rates (K(2)) for the selected analyte in low temperature, in vacuo and in nitrogen atmosphere decreased significantly comparing with that in conventional MAE, which are in agreement with that obtained from experiments. Consequently, the present method was successfully applied to extract labile compound from different food samples. These results showed that low temperature and/or in vacuo environment in microwave-assisted extraction system was especially important to prevent the degradation of labile components and have good potential on the extraction of labile compound in foods, pharmaceutical and natural products. Copyright © 2011 Elsevier B.V. All rights reserved.

Electromagnetic corrections to the hadronic vacuum polarization of the photon within QEDL and QEDM

NASA Astrophysics Data System (ADS)

Bussone, Andrea; Della Morte, Michele; Janowski, Tadeusz

2018-03-01

We compute the leading QED corrections to the hadronic vacuum polarization (HVP) of the photon, relevant for the determination of leptonic anomalous magnetic moments, al. We work in the electroquenched approximation and use dynamical QCD configurations generated by the CLS initiative with two degenerate flavors of nonperturbatively O(a)-improved Wilson fermions. We consider QEDL and QEDM to deal with the finite-volume zero modes. We compare results for the Wilson loops with exact analytical determinations. In addition we make sure that the volumes and photon masses used in QEDM are such that the correct dispersion relation is reproduced by the energy levels extracted from the charged pions two-point functions. Finally we compare results for pion masses and the HVP between QEDL and QEDM. For the vacuum polarization, corrections with respect to the pure QCD case, at fixed pion masses, turn out to be at the percent level.

PREFACE: International Symposium on `Vacuum Science and Technology' (IVS 2007)

NASA Astrophysics Data System (ADS)

Mittal, K. C.; Gupta, S. K.

2008-03-01

The Indian Vacuum Society (established in 1970) has organized a symposium every alternate year on various aspects of vacuum science and technology. There has been considerable participation from R & D establishments, universities and Indian industry in this event. In view of the current global scenario and emerging trends in vacuum technology, this year, the executive committee of IVS felt it appropriate to organize an international symposium at Tata Institute of Fundamental Research, Colaba, Mumbai 400 005 from 29-30 November 2007. This symposium provided a forum for exchange of information among vacuum scientists, technologists and industrialists on recent advances made in the areas of large vacuum systems, vacuum production, its measurement and applications in industry, and material processing in vacuum. Vacuum science and technology has made vital contributions in high tech areas like space, high energy particle accelerators, large plasma systems, electronics, thin films, melting and refining of metals, extraction and processing of advanced materials etc. The main areas covered in the symposium were the production and measurement of vacuums, leak detection, large vacuum systems, vacuum metallurgy, vacuum materials and processing inclusive of applications of vacuum in industry. Large vacuum systems for high energy particle accelerators, plasma devices and light sources are of special significance for this symposium. Vacuum evaporation, hard coatings, thin films, joining techniques, sintering, melting and heat treatment, furnaces and thermo dynamics are also covered in this symposium. There were eighteen invited talks from the best experts in the respective fields and more than one hundred contributed papers. This fact itself indicates the interest that has been generated amongst the scientists, technologists and industrialists in this field. In view of the industrial significance of the vacuum technology, an exhibition of vacuum and vacuum processing related

On Quadratic Divergences in Supergravity, Vacuum Energy and theSupersymmetric Flavor Problem

DOE Office of Scientific and Technical Information (OSTI.GOV)

Gaillard, Mary K.; Nelson, Brent D.

2005-11-18

We examine the phenomenological consequences ofquadratically divergent contributions to the scalar potential insupergravity effective Lagrangians. We focus specifically on the effectof these corrections on the vacuum configurationof scalar fields insoftly-broken supersymmetric theory is and the role these correctionsplay in generating non-diagonal soft scalar masses. Both effects can onlybe properly studied when the divergences are regulated in a manifestlysupersymmetric manner -- something which has ths far been neglected inpast treatments. We show how a supersymmetric regularization can impactpast conclusions about both types of phenomena and discuss what types ofhigh-energy theories are likely to be safe from unwanted flavor-changingneutral current interactions inmore » the context of supergravity theoriesderived from heterotic string compactifications.« less

Induced vacuum energy-momentum tensor in the background of a cosmic string

NASA Astrophysics Data System (ADS)

Sitenko, Yu A.; Vlasii, N. D.

2012-05-01

A massive scalar field is quantized in the background of a cosmic string which is generalized to a static flux-carrying codimension-2 brane in the locally flat multidimensional spacetime. We find that the finite energy-momentum tensor is induced in the vacuum. The dependence of the tensor components on the brane flux and tension, as well as on the coupling to the spacetime curvature scalar, is comprehensively analyzed. The tensor components are holomorphic functions of space dimension, decreasing exponentially with the distance from the brane. The case of the massless quantized scalar field is also considered, and the relevance of Bernoulli’s polynomials of even order for this case is discussed.

Kinetics of ultrasound-assisted extraction of antioxidant polyphenols from food by-products: Extraction and energy consumption optimization.

PubMed

Pradal, Delphine; Vauchel, Peggy; Decossin, Stéphane; Dhulster, Pascal; Dimitrov, Krasimir

2016-09-01

Ultrasound-assisted extraction (UAE) of antioxidant polyphenols from chicory grounds was studied in order to propose a suitable valorization of this food industry by-product. The main parameters influencing the extraction process were identified. A new mathematical model for multi-criteria optimization of UAE was proposed. This kinetic model permitted the following and the prediction of the yield of extracted polyphenols, the antioxidant activity of the obtained extracts and the energy consumption during the extraction process in wide ranges of temperature (20-60°C), ethanol content in the solvent (0-60% (vol.) in ethanol-water mixtures) and ultrasound power (0-100W). After experimental validation of the model, several simulations at different technological restrictions were performed to illustrate the potentiality of the model to find the optimal conditions for obtaining a given yield within minimal process duration or with minimal energy consumption. The advantage of ultrasound assistance was clearly demonstrated both for the reduction of extraction duration and for the reduction of energy consumption. Copyright © 2016 Elsevier B.V. All rights reserved.

Electron stripping processes of H{sup −} ion beam in the 80 kV high voltage extraction column and low energy beam transport line at LANSCE

DOE Office of Scientific and Technical Information (OSTI.GOV)

Draganic, I. N., E-mail: draganic@lanl.gov

Basic vacuum calculations were performed for various operating conditions of the Los Alamos National Neutron Science H{sup −} Cockcroft-Walton (CW) injector and the Ion Source Test Stand (ISTS). The vacuum pressure was estimated for both the CW and ISTS at five different points: (1) inside the H{sup −} ion source, (2) in front of the Pierce electrode, (3) at the extraction electrode, (4) at the column electrode, and (5) at the ground electrode. A static vacuum analysis of residual gases and the working hydrogen gas was completed for the normal ion source working regime. Gas density and partial pressure weremore » estimated for the injected hydrogen gas. The attenuation of H{sup −} beam current and generation of electron current in the high voltage acceleration columns and low energy beam transport lines were calculated. The interaction of H{sup −} ions on molecular hydrogen (H{sub 2}) is discussed as a dominant collision process in describing electron stripping rates. These results are used to estimate the observed increase in the ratio of electrons to H{sup −} ion beam in the ISTS beam transport line.« less

On the hydrophilicity of electrodes for capacitive energy extraction

NASA Astrophysics Data System (ADS)

Lian, Cheng; Kong, Xian; Liu, Honglai; Wu, Jianzhong

2016-11-01

The so-called Capmix technique for energy extraction is based on the cyclic expansion of electrical double layers to harvest dissipative energy arising from the salinity difference between freshwater and seawater. Its optimal performance requires a careful selection of the electrical potentials for the charging and discharging processes, which must be matched with the pore characteristics of the electrode materials. While a number of recent studies have examined the effects of the electrode pore size and geometry on the capacitive energy extraction processes, there is little knowledge on how the surface properties of the electrodes affect the thermodynamic efficiency. In this work, we investigate the Capmix processes using the classical density functional theory for a realistic model of electrolyte solutions. The theoretical predictions allow us to identify optimal operation parameters for capacitive energy extraction with porous electrodes of different surface hydrophobicity. In agreement with recent experiments, we find that the thermodynamic efficiency can be much improved by using most hydrophilic electrodes.

On the hydrophilicity of electrodes for capacitive energy extraction

DOE PAGES

Lian, Cheng; East China Univ. of Science and Technology, Shanghai; Kong, Xian; ...

2016-09-14

The so-called Capmix technique for energy extraction is based on the cyclic expansion of electrical double layers to harvest dissipative energy arising from the salinity difference between freshwater and seawater. Its optimal performance requires a careful selection of the electrical potentials for the charging and discharging processes, which must be matched with the pore characteristics of the electrode materials. While a number of recent studies have examined the effects of the electrode pore size and geometry on the capacitive energy extraction processes, there is little knowledge on how the surface properties of the electrodes affect the thermodynamic efficiency. In thismore » paper, we investigate the Capmix processes using the classical density functional theory for a realistic model of electrolyte solutions. The theoretical predictions allow us to identify optimal operation parameters for capacitive energy extraction with porous electrodes of different surface hydrophobicity. Finally, in agreement with recent experiments, we find that the thermodynamic efficiency can be much improved by using most hydrophilic electrodes.« less

Vacuum statistics and stability in axionic landscapes

DOE Office of Scientific and Technical Information (OSTI.GOV)

Masoumi, Ali; Vilenkin, Alexander, E-mail: ali@cosmos.phy.tufts.edu, E-mail: vilenkin@cosmos.phy.tufts.edu

2016-03-01

We investigate vacuum statistics and stability in random axionic landscapes. For this purpose we developed an algorithm for a quick evaluation of the tunneling action, which in most cases is accurate within 10%. We find that stability of a vacuum is strongly correlated with its energy density, with lifetime rapidly growing as the energy density is decreased. On the other hand, the probability P(B) for a vacuum to have a tunneling action B greater than a given value declines as a slow power law in B. This is in sharp contrast with the studies of random quartic potentials, which foundmore » a fast exponential decline of P(B). Our results suggest that the total number of relatively stable vacua (say, with B>100) grows exponentially with the number of fields N and can get extremely large for N∼> 100. The problem with this kind of model is that the stable vacua are concentrated near the absolute minimum of the potential, so the observed value of the cosmological constant cannot be explained without fine-tuning. To address this difficulty, we consider a modification of the model, where the axions acquire a quadratic mass term, due to their mixing with 4-form fields. This results in a larger landscape with a much broader distribution of vacuum energies. The number of relatively stable vacua in such models can still be extremely large.« less

Carbon nanotubes based vacuum gauge

NASA Astrophysics Data System (ADS)

Rudyk, N. N.; Il'in, O. I.; Il'ina, M. V.; Fedotov, A. A.; Klimin, V. S.; Ageev, O. A.

2017-11-01

We have created an ionization type Vacuum gauge with sensor element based on an array of vertically aligned carbon nanotubes. Obtained asymmetrical current-voltage characteristics at different voltage polarity on the electrode with the CNTs. It was found that when applying a negative potential on an electrode with the CNTs, the current in the gap is higher than at a positive potential. In the pressure range of 1 ÷ 103 Torr vacuum gauge sensitivity was 6 mV/Torr (at a current of 4.5·10-5 A) and in the range of 10-5 ÷ 1 Torr was 10 mV/Torr (at a current of 1.3·10-5 A). It is shown that the energy efficiency of vacuum gauge can be increased in the case where electrode with CNT operates as an emitter of electrons.

Running vacuum cosmological models: linear scalar perturbations

DOE Office of Scientific and Technical Information (OSTI.GOV)

Perico, E.L.D.; Tamayo, D.A., E-mail: elduartep@usp.br, E-mail: tamayo@if.usp.br

In cosmology, phenomenologically motivated expressions for running vacuum are commonly parameterized as linear functions typically denoted by Λ( H {sup 2}) or Λ( R ). Such models assume an equation of state for the vacuum given by P-bar {sub Λ} = - ρ-bar {sub Λ}, relating its background pressure P-bar {sub Λ} with its mean energy density ρ-bar {sub Λ} ≡ Λ/8π G . This equation of state suggests that the vacuum dynamics is due to an interaction with the matter content of the universe. Most of the approaches studying the observational impact of these models only consider the interactionmore » between the vacuum and the transient dominant matter component of the universe. We extend such models by assuming that the running vacuum is the sum of independent contributions, namely ρ-bar {sub Λ} = Σ {sub i} ρ-bar {sub Λ} {sub i} . Each Λ i vacuum component is associated and interacting with one of the i matter components in both the background and perturbation levels. We derive the evolution equations for the linear scalar vacuum and matter perturbations in those two scenarios, and identify the running vacuum imprints on the cosmic microwave background anisotropies as well as on the matter power spectrum. In the Λ( H {sup 2}) scenario the vacuum is coupled with every matter component, whereas the Λ( R ) description only leads to a coupling between vacuum and non-relativistic matter, producing different effects on the matter power spectrum.« less

Dynamics of vacuum-sealed, double-leaf partitions

NASA Astrophysics Data System (ADS)

Kavanaugh, Joshua Stephen

The goal of this research is to investigate the feasibility and potential effectiveness of using vacuum-sealed, double-leaf partitions for applications in noise control. Substantial work has been done previously on double-leaf partitions where the acoustics of the inner chamber and mechanical vibrations of structural supports are passively and actively controlled. The work presented here is unique in that the proposed system aims to eliminate the need for active acoustic control of transmitted acoustic energy by removing all the air between the two panels of the double partition. Therefore, the only remaining energy paths would be along the boundary and at the points where there are intermediate structural supports connecting the two panels. The eventual goal of the research is to develop a high-loss double-leaf partition that simplifies active control by removing the need for control of the air cavity and channeling all the energy into discrete structural paths. The work presented here is a first step towards the goal of designing a high-loss, actively-controlled double-leaf partition with an air-evacuated inner chamber. One experiment is conducted to investigate the effects of various levels of vacuum on the response of a double-leaf partition whose panels are mechanically coupled only at the boundary. Another experiment is conducted which investigates the effect of changing the stiffness of an intermediate support coupling the two panels of a double-leaf partition in which a vacuum has been applied to the inner cavity. The available equipment was able to maintain a 99% vacuum between the panels. Both experiments are accompanied by analytical models used to investigate the importance of various dynamic parameters. Results show that the vacuum-sealed system shows some potential for increased transmission loss, primarily by the changing the natural frequencies of the double-leaf partition.

Casimir switch: steering optical transparency with vacuum forces.

PubMed

Liu, Xi-Fang; Li, Yong; Jing, H

2016-06-03

The Casimir force, originating from vacuum zero-point energy, is one of the most intriguing purely quantum effects. It has attracted renewed interests in current field of nanomechanics, due to the rapid size decrease of on-chip devices. Here we study the optomechanically-induced transparency (OMIT) with a tunable Casimir force. We find that the optical output rate can be significantly altered by the vacuum force, even terminated and then restored, indicating a highly-controlled optical switch. Our result addresses the possibility of designing exotic optical nano-devices by harnessing the power of vacuum.

Chiral vacuum fluctuations in quantum gravity.

PubMed

Magueijo, João; Benincasa, Dionigi M T

2011-03-25

We examine tensor perturbations around a de Sitter background within the framework of Ashtekar's variables and its cousins parameterized by the Immirzi parameter γ. At the classical level we recover standard cosmological perturbation theory, with illuminating insights. Quantization leads to real novelties. In the low energy limit we find a second quantized theory of gravitons which displays different vacuum fluctuations for right and left gravitons. Nonetheless right and left gravitons have the same (positive) energies, resolving a number of paradoxes suggested in the literature. The right-left asymmetry of the vacuum fluctuations depends on γ and the ordering of the Hamiltonian constraint, and it would leave a distinctive imprint in the polarization of the cosmic microwave background, thus opening quantum gravity to observational test.

Decay of the de Sitter vacuum

NASA Astrophysics Data System (ADS)

Anderson, Paul R.; Mottola, Emil; Sanders, Dillon H.

2018-03-01

The decay rate of the Bunch-Davies state of a massive scalar field in the expanding flat spatial sections of de Sitter space is determined by an analysis of the particle pair creation process in real time. The Feynman definition of particle and antiparticle Fourier mode solutions of the scalar wave equation and their adiabatic phase analytically continued to the complexified time domain show conclusively that the Bunch-Davies state is not the vacuum state at late times. The closely analogous creation of charged particle pairs in a uniform electric field is reviewed and Schwinger's result for the vacuum decay rate is recovered by this same real time analysis. The vacuum decay rate in each case is also calculated by switching the background field on adiabatically, allowing it to act for a very long time, and then adiabatically switching it off again. In both the uniform electric field and de Sitter cases, the particles created while the field is switched on are verified to be real, in the sense that they persist in the final asymptotic flat zero-field region. In the de Sitter case, there is an interesting residual dependence of the rate on how the de Sitter phase is ended, indicating a greater sensitivity to spatial boundary conditions. The electric current of the created particles in the E -field case and their energy density and pressure in the de Sitter case are also computed, and the magnitude of their backreaction effects on the background field estimated. Possible consequences of the Hubble scale instability of the de Sitter vacuum for cosmology, vacuum dark energy, and the cosmological "constant" problem are discussed.

Overview of High Power Vacuum Dry RF Load Designs

DOE Office of Scientific and Technical Information (OSTI.GOV)

Krasnykh, Anatoly

2015-08-27

A specific feature of RF linacs based on the pulsed traveling wave (TW) mode of operation is that only a portion of the RF energy is used for the beam acceleration. The residual RF energy has to be terminated into an RF load. Higher accelerating gradients require higher RF sources and RF loads, which can stably terminate the residual RF power. RF feeders (from the RF source though the accelerating section to the load) are vacuumed to transmit multi-megawatt high power RF. This overview will outline vacuumed RF loads only. A common method to terminate multi-MW RF power is tomore » use circulated water (or other liquid) as an absorbing medium. A solid dielectric interface (a high quality ceramic) is required to separate vacuum and liquid RF absorber mediums. Using such RF load approaches in TW linacs is troubling because there is a fragile ceramic window barrier and a failure could become catastrophic for linac vacuum and RF systems. Traditional loads comprising of a ceramic disk have limited peak and average power handling capability and are therefore not suitable for high gradient TW linacs. This overview will focus on ''vacuum dry'' or ''all-metal'' loads that do not employ any dielectric interface between vacuum and absorber. The first prototype is an original design of RF loads for the Stanford Two-Mile Accelerator.« less

Compressed Air/Vacuum Transportation Techniques

NASA Astrophysics Data System (ADS)

Guha, Shyamal

2011-03-01

General theory of compressed air/vacuum transportation will be presented. In this transportation, a vehicle (such as an automobile or a rail car) is powered either by compressed air or by air at near vacuum pressure. Four version of such transportation is feasible. In all versions, a ``c-shaped'' plastic or ceramic pipe lies buried a few inches under the ground surface. This pipe carries compressed air or air at near vacuum pressure. In type I transportation, a vehicle draws compressed air (or vacuum) from this buried pipe. Using turbine or reciprocating air cylinder, mechanical power is generated from compressed air (or from vacuum). This mechanical power transferred to the wheels of an automobile (or a rail car) drives the vehicle. In type II-IV transportation techniques, a horizontal force is generated inside the plastic (or ceramic) pipe. A set of vertical and horizontal steel bars is used to transmit this force to the automobile on the road (or to a rail car on rail track). The proposed transportation system has following merits: virtually accident free; highly energy efficient; pollution free and it will not contribute to carbon dioxide emission. Some developmental work on this transportation will be needed before it can be used by the traveling public. The entire transportation system could be computer controlled.

Cyclodextrin-enhanced extraction and energy transfer of carcinogens in complex oil environments.

PubMed

Serio, Nicole; Chanthalyma, Chitapom; Prignano, Lindsey; Levine, Mindy

2013-11-27

Reported herein is the use of γ-cyclodextrin for two tandem functions: (a) the extraction of carcinogenic polycyclic aromatic hydrocarbons (PAHs) from oil samples into aqueous solution and (b) the promotion of highly efficient energy transfer from the newly extracted PAHs to a high-quantum-yield fluorophore. The extraction proceeded in moderate to good efficiencies, and the resulting cyclodextrin-promoted energy transfer led to a new, brightly fluorescent signal in aqueous solution. The resulting dual-function system (extraction followed by energy transfer) has significant relevance in the environmental detection and cleanup of oil-spill-related carcinogens.

Modelling of nectarine drying under near infrared - Vacuum conditions.

PubMed

Alaei, Behnam; Chayjan, Reza Amiri

2015-01-01

Drying of nectarine slices was performed to determine the thermal and physical properties in order to reduce product deterioration due to chemical reactions, facilitate storage and lower transportation costs. Because nectarine slices are sensitive to heat with long drying period, the selection of a suitable drying approach is a challenging task. Infrared-vacuum drying can be used as an appropriate method for susceptible materials with high moisture content such as nectarine slices. Modelling of nectarine slices drying was carried out in a thin layer near infraredvacuum conditions. Drying of the samples was implemented at the absolute pressures of 20, 40 and 60 kPa and drying temperatures of 50, 60 and 70°C. Drying behaviour of nectarine slices, as well as the effect of drying conditions on moisture loss trend, drying rate, effective diffusion coefficient, activation energy, shrinkage, colour and energy consumption of nectarine slices, dried in near infrared-vacuum dryer are discussed in this study. Six mathematical models were used to predict the moisture ratio of the samples in thin layer drying. The Midilli model had supremacy in prediction of nectarine slices drying behaviour. The maximum drying rates of the samples were between 0.014-0.047 gwater/gdry material·min. Effective moisture diffusivity of the samples was estimated in the ranges of 2.46·10-10 to 6.48·10-10 m2/s. Activation energy were computed between 31.28 and 35.23 kJ/mol. Minimum shrinkage (48.4%) and total colour difference (15.1) were achieved at temperature of 50°C and absolute pressure of 20 kPa. Energy consumption of the tests was estimated in the ranges of 0.129 to 0.247 kWh. Effective moisture diffusivity was increased with decrease of vacuum pressure and increase of drying temperature but effect of drying temperature on effective moisture diffusivity of nectarine slices was more than vacuum pressure. Activation energy was decreased with decrease in absolute pressure. Total colour

DEMONSTRATION BULLETIN: IN-SITU VACUUM EXRACTION: TERRA VAC, INC.

EPA Science Inventory

This in-situ vacuum extraction technology is a process for the removal and venting of volatile organic compounds (VOCs) from the vadose or unsaturated zone of soils. Often, these compounds can be removed from the vadose zone before they have a chance to contaminate groundwater. ...

Techno-economic analysis of extraction-based separation systems for acetone, butanol, and ethanol recovery and purification.

PubMed

Grisales Díaz, Víctor Hugo; Olivar Tost, Gerard

2017-01-01

Dual extraction, high-temperature extraction, mixture extraction, and oleyl alcohol extraction have been proposed in the literature for acetone, butanol, and ethanol (ABE) production. However, energy and economic evaluation under similar assumptions of extraction-based separation systems are necessary. Hence, the new process proposed in this work, direct steam distillation (DSD), for regeneration of high-boiling extractants was compared with several extraction-based separation systems. The evaluation was performed under similar assumptions through simulation in Aspen Plus V7.3 ® software. Two end distillation systems (number of non-ideal stages between 70 and 80) were studied. Heat integration and vacuum operation of some units were proposed reducing the energy requirements. Energy requirement of hybrid processes, substrate concentration of 200 g/l, was between 6.4 and 8.3 MJ-fuel/kg-ABE. The minimum energy requirements of extraction-based separation systems, feeding a water concentration in the substrate equivalent to extractant selectivity, and ideal assumptions were between 2.6 and 3.5 MJ-fuel/kg-ABE, respectively. The efficiencies of recovery systems for baseline case and ideal evaluation were 0.53-0.57 and 0.81-0.84, respectively. The main advantages of DSD were the operation of the regeneration column at atmospheric pressure, the utilization of low-pressure steam, and the low energy requirements of preheating. The in situ recovery processes, DSD, and mixture extraction with conventional regeneration were the approaches with the lowest energy requirements and total annualized costs.

Retention of antioxidant capacity of vacuum microwave dried cranberry.

PubMed

Leusink, Gwen J; Kitts, David D; Yaghmaee, Parastoo; Durance, Tim

2010-04-01

In this study, cranberries were dried by vacuum-microwave drying (VMD), freeze-drying (FD), or hot air-drying (AD), to compare the effects of different drying processes on both physical changes as well as the retention of bioactive components in dried samples. Total porosity (%) and average pore radius of dehydrated cranberries were greater using VMD compared to FD and AD (P < 0.05). Crude methanol cranberry powdered extracts were fractionated by solid phase extraction (SPE) into organic acid-, total phenolics-, anthocyanin-, or proanthocyanidin-enriched extracts, respectively. The chemical composition of the 60% acidified methanol fractions contained cyanidin-3-galactoside, cyanidin-3-arabinoside, peonidin-3-galactoside, and peonidin-3-arabinoside, as assessed by HPLC. Antioxidant activities of cranberry fractions were measured using chemical ORAC and ABTS methods. The 60% acidified methanol fraction had a significantly higher (P < 0.05) antioxidant potential than the other chemical fractions, which was largely attributed to the relatively higher anthocyanin content. In general, vacuum-microwave drying and freeze-drying resulted in similar retention of anthocyanins and antioxidant activity, which were both relatively higher (P < 0.05) than that recovered from cranberries dried by hot air drying.

Thermodynamic performance of multi-stage gradational lead screw vacuum pump

NASA Astrophysics Data System (ADS)

Zhao, Fan; Zhang, Shiwei; Sun, Kun; Zhang, Zhijun

2018-02-01

As a kind of dry mechanical vacuum pump, the twin-screw vacuum pump has an outstanding pumping performance during operation, widely used in the semiconductor industry. Compared with the constant lead screw (CLS) vacuum pump, the gradational lead screw (GLS) vacuum pump is more popularly applied in recent years. Nevertheless, not many comparative studies on the thermodynamic performance of GLS vacuum pump can be found in the literature. Our study focuses on one type of GLS vacuum pump, the multi-stage gradational lead screw (MGLS) vacuum pump, gives a detailed description of its construction and illustrates it with the drawing. Based on the structural analysis, the thermodynamic procedure is divided into four distinctive processes, including sucking process, transferring (compressing) process, backlashing process and exhausting process. The internal mechanism of each process is qualitatively illustrated and the mathematical expressions of seven thermodynamic parameters are given under the ideal situation. The performance curves of MGLS vacuum pump are plotted by MATLAB software and compared with those of the CLS vacuum pump in the same case. The results can well explain why the MGLS vacuum pump has more favorable pumping performance than the CLS vacuum pump in saving energy, reducing noise and heat dissipation.

Energy extraction from a large-scale microbial fuel cell system treating municipal wastewater

NASA Astrophysics Data System (ADS)

Ge, Zheng; Wu, Liao; Zhang, Fei; He, Zhen

2015-11-01

Development of microbial fuel cell (MFC) technology must address the challenges associated with energy extraction from large-scale MFC systems consisting of multiple modules. Herein, energy extraction is investigated with a 200-L MFC system (effective volume of 100 L for this study) treating actual municipal wastewater. A commercially available energy harvesting device (BQ 25504) is used successfully to convert 0.8-2.4 V from the MFCs to 5 V for charging ultracapacitors and running a DC motor. Four different types of serial connection containing different numbers of MFC modules are examined for energy extraction and conversion efficiency. The connection containing three rows of the MFCs has exhibited the best performance with the highest power output of ∼114 mW and the conversion efficiency of ∼80%. The weak performance of one-row MFCs negatively affects the overall performance of the connected MFCs in terms of both energy production and conversion. Those results indicate that an MFC system with balanced performance among individual modules will be critical to energy extraction. Future work will focus on application of the extracted energy to support MFC operation.

Self-powered switch-controlled nucleic acid extraction system.

PubMed

Han, Kyungsup; Yoon, Yong-Jin; Shin, Yong; Park, Mi Kyoung

2016-01-07

Over the past few decades, lab-on-a-chip (LOC) technologies have played a great role in revolutionizing the way in vitro medical diagnostics are conducted and transforming bulky and expensive laboratory instruments and labour-intensive tests into easy to use, cost-effective miniaturized systems with faster analysis time, which can be used for near-patient or point-of-care (POC) tests. Fluidic pumps and valves are among the key components for LOC systems; however, they often require on-line electrical power or batteries and make the whole system bulky and complex, therefore limiting its application to POC testing especially in low-resource setting. This is particularly problematic for molecular diagnostics where multi-step sample processing (e.g. lysing, washing, elution) is necessary. In this work, we have developed a self-powered switch-controlled nucleic acid extraction system (SSNES). The main components of SSNES are a powerless vacuum actuator using two disposable syringes and a switchgear made of PMMA blocks and an O-ring. In the vacuum actuator, an opened syringe and a blocked syringe are bound together and act as a working syringe and an actuating syringe, respectively. The negative pressure in the opened syringe is generated by a restoring force of the compressed air inside the blocked syringe and utilized as the vacuum source. The Venus symbol shape of the switchgear provides multiple functions including being a reagent reservoir, a push-button for the vacuum actuator, and an on-off valve. The SSNES consists of three sets of vacuum actuators, switchgears and microfluidic components. The entire system can be easily fabricated and is fully disposable. We have successfully demonstrated DNA extraction from a urine sample using a dimethyl adipimidate (DMA)-based extraction method and the performance of the DNA extraction has been confirmed by genetic (HRAS) analysis of DNA biomarkers from the extracted DNAs using the SSNES. Therefore, the SSNES can be widely

Vacuum mechatronics

NASA Technical Reports Server (NTRS)

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

1989-01-01

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.

Natural vacuum electronics

NASA Technical Reports Server (NTRS)

Leggett, Nickolaus

1990-01-01

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.

Kinetics of scrap tyre pyrolysis under vacuum conditions

DOE Office of Scientific and Technical Information (OSTI.GOV)

Lopez, Gartzen; Aguado, Roberto; Olazar, Martin

2009-10-15

Scrap tyre pyrolysis under vacuum is attractive because it allows easier product condensation and control of composition (gas, liquid and solid). With the aim of determining the effect of vacuum on the pyrolysis kinetics, a study has been carried out in thermobalance. Two data analysis methods have been used in the kinetic study: (i) the treatment of experimental data of weight loss and (ii) the deconvolution of DTG (differential thermogravimetry) curve. The former allows for distinguishing the pyrolysis of the three main components (volatile components, natural rubber and styrene-butadiene rubber) according to three successive steps. The latter method identifies themore » kinetics for the pyrolysis of individual components by means of DTG curve deconvolution. The effect of vacuum in the process is significant. The values of activation energy for the pyrolysis of individual components of easier devolatilization (volatiles and NR) are lower for pyrolysis under vacuum with a reduction of 12 K in the reaction starting temperature. The kinetic constant at 503 K for devolatilization of volatile additives at 0.25 atm is 1.7 times higher than that at 1 atm, and that corresponding to styrene-butadiene rubber at 723 K is 2.8 times higher. Vacuum enhances the volatilization and internal diffusion of products in the pyrolysis process, which contributes to attenuating the secondary reactions of the repolymerization and carbonization of these products on the surface of the char (carbon black). The higher quality of carbon black is interesting for process viability. The large-scale implementation of this process in continuous mode requires a comparison to be made between the economic advantages of using a vacuum and the energy costs, which will be lower when the technologies used for pyrolysis require a lower ratio between reactor volume and scrap tyre flow rate.« less

Kinetics of scrap tyre pyrolysis under vacuum conditions.

PubMed

Lopez, Gartzen; Aguado, Roberto; Olazar, Martín; Arabiourrutia, Miriam; Bilbao, Javier

2009-10-01

Scrap tyre pyrolysis under vacuum is attractive because it allows easier product condensation and control of composition (gas, liquid and solid). With the aim of determining the effect of vacuum on the pyrolysis kinetics, a study has been carried out in thermobalance. Two data analysis methods have been used in the kinetic study: (i) the treatment of experimental data of weight loss and (ii) the deconvolution of DTG (differential thermogravimetry) curve. The former allows for distinguishing the pyrolysis of the three main components (volatile components, natural rubber and styrene-butadiene rubber) according to three successive steps. The latter method identifies the kinetics for the pyrolysis of individual components by means of DTG curve deconvolution. The effect of vacuum in the process is significant. The values of activation energy for the pyrolysis of individual components of easier devolatilization (volatiles and NR) are lower for pyrolysis under vacuum with a reduction of 12K in the reaction starting temperature. The kinetic constant at 503K for devolatilization of volatile additives at 0.25atm is 1.7 times higher than that at 1atm, and that corresponding to styrene-butadiene rubber at 723K is 2.8 times higher. Vacuum enhances the volatilization and internal diffusion of products in the pyrolysis process, which contributes to attenuating the secondary reactions of the repolymerization and carbonization of these products on the surface of the char (carbon black). The higher quality of carbon black is interesting for process viability. The large-scale implementation of this process in continuous mode requires a comparison to be made between the economic advantages of using a vacuum and the energy costs, which will be lower when the technologies used for pyrolysis require a lower ratio between reactor volume and scrap tyre flow rate.

VACUUM TRAP

DOEpatents

Gordon, H.S.

1959-09-15

An improved adsorption vacuum trap for use in vacuum systems was designed. The distinguishing feature is the placement of a plurality of torsionally deformed metallic fins within a vacuum jacket extending from the walls to the central axis so that substantially all gas molecules pass through the jacket will impinge upon the fin surfaces. T fins are heated by direct metallic conduction, thereby ol taining a uniform temperature at the adeorbing surfaces so that essentially all of the condensible impurities from the evacuating gas are removed from the vacuum system.

SLAC All Access: Vacuum Microwave Device Department

ScienceCinema

Haase, Andy

2018-05-11

The Vacuum Microwave Device Department (VMDD) builds the devices that make SLAC's particle accelerators go. These devices, called klystrons, generate intense waves of microwave energy that rocket subatomic particles up to nearly the speed of light.

SLAC All Access: Vacuum Microwave Device Department

DOE Office of Scientific and Technical Information (OSTI.GOV)

Haase, Andy

2012-10-09

The Vacuum Microwave Device Department (VMDD) builds the devices that make SLAC's particle accelerators go. These devices, called klystrons, generate intense waves of microwave energy that rocket subatomic particles up to nearly the speed of light.

Tidal energy extraction: renewable, sustainable and predictable.

PubMed

Nicholls-Lee, R F; Turnock, S R

2008-01-01

The tidal flow of sea water induced by planetary motion is a potential source of energy if suitable systems can be designed and operated in a cost-effective manner This paper examines the physical origins of the tides and how the local currents are influenced by the depth of the seabed and presence of land mass and associated coastal features. The available methods of extracting energy from tidal movement are classified into devices that store and release potential energy and those that capture kinetic energy directly. A survey is made of candidate designs and, for the most promising, the likely efficiency of energy conversion and methods of installing them are considered. Overall, the need to reduce CO2 emissions, a likely continued rise in fossil fuel cost will result in a significantly increased use of tidal energy. What is still required, especially for kinetic energy devices, is a much greater understanding of how they can be designed to withstand long-term immersion in the marine environment.

Comments on real tachyon vacuum solution without square roots

NASA Astrophysics Data System (ADS)

Arroyo, E. Aldo

2018-01-01

We analyze the consistency of a recently proposed real tachyon vacuum solution without square roots in open bosonic string field theory. We show that the equation of motion contracted with the solution itself is satisfied. Additionally, by expanding the solution in the basis of the curly ℒ0 and the traditional L 0 eigenstates, we evaluate numerically the vacuum energy and obtain a result in agreement with Sen's conjecture.

State-of-the-art of recycling e-wastes by vacuum metallurgy separation.

PubMed

Zhan, Lu; Xu, Zhenming

2014-12-16

In recent era, more and more electric and electronic equipment wastes (e-wastes) are generated that contain both toxic and valuable materials in them. Most studies focus on the extraction of valuable metals like Au, Ag from e-wastes. However, the recycling of metals such as Pb, Cd, Zn, and organics has not attracted enough attentions. Vacuum metallurgy separation (VMS) processes can reduce pollution significantly using vacuum technique. It can effectively recycle heavy metals and organics from e-wastes in an environmentally friendly way, which is beneficial for both preventing the heavy metal contaminations and the sustainable development of resources. VMS can be classified into several methods, such as vacuum evaporation, vacuum carbon reduction and vacuum pyrolysis. This paper respectively reviews the state-of-art of these methods applied to recycling heavy metals and organics from several kinds of e-wastes. The method principle, equipment used, separating process, optimized operating parameters and recycling mechanism of each case are illustrated in details. The perspectives on the further development of e-wastes recycling by VMS are also presented.

Solar energy converters based on multi-junction photoemission solar cells.

PubMed

Tereshchenko, O E; Golyashov, V A; Rodionov, A A; Chistokhin, I B; Kislykh, N V; Mironov, A V; Aksenov, V V

2017-11-23

Multi-junction solar cells with multiple p-n junctions made of different semiconductor materials have multiple bandgaps that allow reducing the relaxation energy loss and substantially increase the power-conversion efficiency. The choice of materials for each sub-cell is very limited due to the difficulties in extracting the current between the layers caused by the requirements for lattice- and current-matching. We propose a new vacuum multi-junction solar cell with multiple p-n junctions separated by vacuum gaps that allow using different semiconductor materials as cathode and anode, both activated to the state of effective negative electron affinity (NEA). In this work, the compact proximity focused vacuum tube with the GaAs(Cs,O) photocathode and AlGaAs/GaAs-(Cs,O) anode with GaAs quantum wells (QWs) is used as a prototype of a vacuum single-junction solar cell. The photodiode with the p-AlGaAs/GaAs anode showed the spectral power-conversion efficiency of about 1% at V bias  = 0 in transmission and reflection modes, while, at V bias  = 0.5 V, the efficiency increased up to 10%. In terms of energy conservation, we found the condition at which the energy cathode-to-anode transition was close to 1. Considering only the energy conservation part, the NEA-cell power-conversion efficiency can rich a quantum yield value which is measured up to more than 50%.

Electron acceleration from rest to GeV energy by chirped axicon Gaussian laser pulse in vacuum in the presence of wiggler magnetic field

NASA Astrophysics Data System (ADS)

Kant, Niti; Rajput, Jyoti; Singh, Arvinder

2018-03-01

This paper presents a scheme of electron energy enhancement by employing frequency - chirped lowest order axicon focussed radially polarised (RP) laser pulse in vacuum under the influence of wiggler magnetic field. Terawatt RP laser can be focussed down to ∼5μm by an axicon optical element, which produces an intense longitudinal electric field. This unique property of axicon focused Gaussian RP laser pulse is employed for direct electron acceleration in vacuum. A linear frequency chirp increases the time duration of laser-electron interaction, whereas, the applied magnetic wiggler helps in improving the strength of ponderomotive force v→ ×B→ and periodically deflects electron in order to keep it traversing in the accelerating phase up to longer distance. Numerical simulations have been carried out to investigate the influence of laser, frequency chirp and magnetic field parameters on electron energy enhancement. It is noticed that an electron from rest can be accelerated up to GeV energy under optimized laser and magnetic field parameters. Significant enhancement in the electron energy gain of the order of 11.2 GeV is observed with intense chirped laser pulse in the presence of wiggler magnetic field of strength 96.2 kG.

Solar cells for lunar applications by vacuum evaporation of lunar regolith materials

NASA Technical Reports Server (NTRS)

Ignatiev, Alex

1991-01-01

The National Space Exploration Initiative, specifically the Lunar component, has major requirements for technology development of critical systems, one of which is electrical power. The availability of significant electrical power on the surface of the Moon is a principal driver defining the complexity of the lunar base. Proposals to generate power on the Moon include both nuclear and solar (photovoltaic) systems. A more efficient approach is to attempt utilization of the existing lunar resources to generate the power systems. Synergism may occur from the fact that there have already been lunar materials processing techniques proposed for the extraction of oxygen that would have, as by-products, materials that could be specifically used to generate solar cells. The lunar environment is a vacuum with pressures generally in the 1 x 10(exp -10) torr range. Such conditions provide an ideal environment for direct vacuum deposition of thin film solar cells using the waste silicon, iron, and TiO2 available from the lunar regolith processing meant to extract oxygen. It is proposed, therefore, to grow by vacuum deposition, thin film silicon solar cells from the improved regolith processing by-products.

Small dark energy and stable vacuum from Dilaton-Gauss-Bonnet coupling in TMT

NASA Astrophysics Data System (ADS)

Guendelman, Eduardo I.; Nishino, Hitoshi; Rajpoot, Subhash

2017-04-01

In two measures theories (TMT), in addition to the Riemannian measure of integration, being the square root of the determinant of the metric, we introduce a metric-independent density Φ in four dimensions defined in terms of scalars \\varphi _a by Φ =\\varepsilon ^{μ ν ρ σ } \\varepsilon _{abcd} (partial _{μ }\\varphi _a)(partial _{ν }\\varphi _b) (partial _{ρ }\\varphi _c) (partial _{σ }\\varphi _d). With the help of a dilaton field φ we construct theories that are globally scale invariant. In particular, by introducing couplings of the dilaton φ to the Gauss-Bonnet (GB) topological density {√{-g}} φ ( R_{μ ν ρ σ }^2 - 4 R_{μ ν }^2 + R^2 ) we obtain a theory that is scale invariant up to a total divergence. Integration of the \\varphi _a field equation leads to an integration constant that breaks the global scale symmetry. We discuss the stabilizing effects of the coupling of the dilaton to the GB-topological density on the vacua with a very small cosmological constant and the resolution of the `TMT Vacuum-Manifold Problem' which exists in the zero cosmological-constant vacuum limit. This problem generically arises from an effective potential that is a perfect square, and it gives rise to a vacuum manifold instead of a unique vacuum solution in the presence of many different scalars, like the dilaton, the Higgs, etc. In the non-zero cosmological-constant case this problem disappears. Furthermore, the GB coupling to the dilaton eliminates flat directions in the effective potential, and it totally lifts the vacuum-manifold degeneracy.

Extraction of jet properties from two particle azimuthal correlations in proton-proton and gold+gold collisions at center of mass energy = 200 GeV

NASA Astrophysics Data System (ADS)

Constantin, Paul

Two particle azimuthal correlation functions measured in pp and AuAu collisions at sNN = 200 GeV at midrapidity with the central arms of the PHENIX detector are analyzed in order to extract the properties of hadronic jets produced in QCD vacuum and highly excited QCD media, like the jet shape parameters jT and kT, the jet conditional yields (number of associated hadrons per high pT trigger hadron) and the jet fragmentation function. The analysis of pp data starts with the measurement of the vacuum fragmentation function from which the pT dependence of the mean fragmentation momentum fraction is extracted. We obtain a constant value of = 0.74 +/- 0.02 for pT above 3 GeV/c. Soft (non-perturbative) parton fragmentation becomes significant below 3 GeV/c and the slope of the fragmentation function is pT dependent in this region. Gaussian fits to jet induced azimuthal correlations are employed to measure the mean jet fragmentation transverse momentum <| jTy|> = 359 +/- 11 (stat) +/- 6 (syst) MeV/c and the mean partonic transverse momentum <|k Ty|> = 964 +/- 49 (stat) +/- 16 (syst) MeV/c. The analysis of AuAu data is based on azimuthal correlation functions between charged hadrons in the 1.5--3 GeV/c and 3--5 GeV/c pT regions in five classes of collision centrality. The mean jet fragmentation transverse momentum <|jTy|> is centrality independent and consistent with the value in pp data mentioned above. A strong broadening with the centrality of the extracted mean partonic transverse momentum <|kTy|> (multiplied by ) is observed. This is an important finding because hadronic jet quenching through energy loss is expected to be accompanied by a broadening effect. Another important finding is that the jet conditional yields in both the near (Deltaφ ˜ 0) and away (Deltaφ ˜ pi) regions exhibit a slightly raising trend with centrality. This was also expected to accompany the jet quenching found at higher pT based on simple energy conservation considerations.

Effect of power shape on energy extraction from microbial fuel cell

NASA Astrophysics Data System (ADS)

Alaraj, Muhannad; Feng, Shuo; Roane, Timberley M.; Park, Jae-Do

2017-10-01

Microbial fuel cells (MFCs) generate renewable energy in the form of direct current (DC) power. Harvesting energy from MFCs started with passive components such as resistors and capacitors, then charge pumps were introduced with some more advantages. Power electronics converters were later preferred due to their higher efficiency and controllability; however, they introduce high frequency current ripple due to their high frequency switching. In this paper, the effect of shape of power extraction on MFC performance was investigated using three types of current shapes: continuous, square-wave, and triangular-wave. Simultaneously, chemical parameters, such as pH, dissolved oxygen, electrical conductivity, and redox potential, in the anode chamber were monitored to see how these parameters change with the shape of the electrical power extraction. Results showed that the shape of the extracted current did not have a substantial effect on the MFC life span, output power, and energy extraction, nor on the chemical parameters. The outcome of this study provided insight for the electrical impact by power electronics converters on some microbial and chemical aspects of an MFC system.

Carbon nanotube vacuum gauges utilizing long, dissipative tubes

NASA Astrophysics Data System (ADS)

Kaul, Anupama B.; Manohara, Harish M.

2008-04-01

A carbon nanotube-based thermal conductivity vacuum gauge is described which utilizes 5-10 μm long diffusively contacted SWNTs for vacuum sensing. By etching the thermal SiO II beneath the tubes and minimizing heat conduction through the substrate, pressure sensitivity was extended toward higher vacuums. The pressure response of unannealed and annealed devices was compared to that of released devices. The released devices showed sensitivity to pressure as low as 1 x 10 -6 Torr. The sensitivity increased more dramatically with power for the released device compared to that of the unreleased device. Low temperature electronic transport measurements of the tubes were suggestive of a thermally activated hopping mechanism where the activation energy for hopping was calculated to be ~ 39 meV.

Comparison of vacuum and non-vacuum urine tubes for urinary sediment analysis.

PubMed

Topcuoglu, Canan; Sezer, Sevilay; Kosem, Arzu; Ercan, Mujgan; Turhan, Turan

2017-12-01

Urine collection systems with aspiration system for vacuum tubes are becoming increasingly common for urinalysis, especially for microscopic examination of the urine. In this study, we aimed to examine whether vacuum aspiration of the urine sample has any adverse effect on sediment analysis by comparing results from vacuum and non-vacuum urine tubes. The study included totally 213 urine samples obtained from inpatients and outpatients in our hospital. Urine samples were collected to containers with aspiration system for vacuum tubes. Each sample was aliquoted to both vacuum and non-vacuum urine tubes. Urinary sediment analysis was performed using manual microscope. Results were evaluated using chi-square test. Comparison of the sediment analysis results from vacuum and non-vacuum urine tubes showed that results were highly concordant for erythrocyte, leukocyte and epithelial cells (gamma values 1, 0.997, and 0.994, respectively; p < .001). Results were also concordant for urinary casts, crystals and yeast (kappa values 0.815, 0.945 and 1, respectively; p < .001). The results show that in urinary sediment analysis, vacuum aspiration has no adverse effect on the cellular components except on casts.

Atmospheres and spectra of strongly magnetized neutron stars - II. The effect of vacuum polarization

NASA Astrophysics Data System (ADS)

Ho, Wynn C. G.; Lai, Dong

2003-01-01

We study the effect of vacuum polarization on the atmosphere structure and radiation spectra of neutron stars with surface magnetic fields B= 1014-1015 G, as appropriate for magnetars. Vacuum polarization modifies the dielectric property of the medium and gives rise to a resonance feature in the opacity; this feature is narrow and occurs at a photon energy that depends on the plasma density. Vacuum polarization can also induce resonant conversion of photon modes via a mechanism analogous to the Mikheyev-Smirnov-Wolfenstein (MSW) mechanism for neutrino oscillation. We construct atmosphere models in radiative equilibrium with an effective temperature of a few ×106 K by solving the full radiative transfer equations for both polarization modes in a fully ionized hydrogen plasma. We discuss the subtleties in treating the vacuum polarization effects in the atmosphere models and present approximate solutions to the radiative transfer problem which bracket the true answer. We show from both analytic considerations and numerical calculations that vacuum polarization produces a broad depression in the X-ray flux at high energies (a few keV <~E<~ a few tens of keV) as compared to models without vacuum polarization; this arises from the density dependence of the vacuum resonance feature and the large density gradient present in the atmosphere. Thus the vacuum polarization effect softens the high-energy tail of the thermal spectrum, although the atmospheric emission is still harder than the blackbody spectrum because of the non-grey opacities. We also show that the depression of continuum flux strongly suppresses the equivalent width of the ion cyclotron line and therefore makes the line more difficult to observe.

ARRAY OPTIMIZATION FOR TIDAL ENERGY EXTRACTION IN A TIDAL CHANNEL – A NUMERICAL MODELING ANALYSIS

DOE Office of Scientific and Technical Information (OSTI.GOV)

Yang, Zhaoqing; Wang, Taiping; Copping, Andrea

This paper presents an application of a hydrodynamic model to simulate tidal energy extraction in a tidal dominated estuary in the Pacific Northwest coast. A series of numerical experiments were carried out to simulate tidal energy extraction with different turbine array configurations, including location, spacing and array size. Preliminary model results suggest that array optimization for tidal energy extraction in a real-world site is a very complex process that requires consideration of multiple factors. Numerical models can be used effectively to assist turbine siting and array arrangement in a tidal turbine farm for tidal energy extraction.

Variational methods in supersymmetric lattice field theory: The vacuum sector

DOE Office of Scientific and Technical Information (OSTI.GOV)

Duncan, A.; Meyer-Ortmanns, H.; Roskies, R.

1987-12-15

The application of variational methods to the computation of the spectrum in supersymmetric lattice theories is considered, with special attention to O(N) supersymmetric sigma models. Substantial cancellations are found between bosonic and fermionic contributions even in approximate Ansa$uml: tze for the vacuum wave function. The nonlinear limit of the linear sigma model is studied in detail, and it is shown how to construct an appropriate non-Gaussian vacuum wave function for the nonlinear model. The vacuum energy is shown to be of order unity in lattice units in the latter case, after infinite cancellations.

Design and fabrication of the vacuum systems for TPS pulsed septum magnets

NASA Astrophysics Data System (ADS)

Chan, C. K.; Chang, C. C.; Chen, C. L.; Yang, C. S.; Chen, C. S.; Lin, F. Y.; Chen, J. R.

2014-11-01

Three in-air pulsed septum magnets were developed to inject and extract electron beams for the 3 GeV synchrotron facility, the Taiwan Photon Source (TPS). The vacuum chamber is a novel combined aluminium-stainless steel design, using a bimetallic flange to connect the two material types. To evaluate the vacuum performances of these vacuum chambers, we set up a test bench at which we simultaneously measure the rates of thermal outgassing of the aluminium chamber and the septum tube with a throughput method. The test result indicates that the rate q72 of thermal outgassing measured after 1 day from baking at 150 °C was 1×10-13 mbar L s-1 cm-2. The magnetic leakage measurements show the combination of conductor slitting, magnetic shielding and the aluminium vacuum chamber reduce the peak value of the leakage field integral to ~10 G cm along the trajectory of the stored beam.

Towards extracting the timelike pion form factor on CLS twoflavour ensembles

NASA Astrophysics Data System (ADS)

Erben, Felix; Green, Jeremy; Mohler, Daniel; Wittig, Hartmut

2018-03-01

Results are presented from an ongoing study of the ρ resonance. The focus is on CLS 2-flavour ensembles generated using O(a) improved Wilson fermions with pion masses ranging from 265 to 437 MeV. The energy levels are extracted by solving the GEVP of correlator matrices, created with the distillation approach involving ρ and ππ interpolators. The study is done in the centre-of-mass frame and several moving frames. One aim of this work is to extract the timelike pion form factor after applying the Lüscher formalism. We therefore plan to integrate this study with the existing Mainz programme for the calculation of the hadronic vacuum polarization contribution to the muon g - 2.

Double synchronized switch harvesting (DSSH): a new energy harvesting scheme for efficient energy extraction.

PubMed

Lallart, Mickaël; Garbuio, Lauric; Petit, Lionel; Richard, Claude; Guyomar, Daniel

2008-10-01

This paper presents a new technique for optimized energy harvesting using piezoelectric microgenerators called double synchronized switch harvesting (DSSH). This technique consists of a nonlinear treatment of the output voltage of the piezoelectric element. It also integrates an intermediate switching stage that ensures an optimal harvested power whatever the load connected to the microgenerator. Theoretical developments are presented considering either constant vibration magnitude, constant driving force, or independent extraction. Then experimental measurements are carried out to validate the theoretical predictions. This technique exhibits a constant output power for a wide range of load connected to the microgenerator. In addition, the extracted power obtained using such a technique allows a gain up to 500% in terms of maximal power output compared with the standard energy harvesting method. It is also shown that such a technique allows a fine-tuning of the trade-off between vibration damping and energy harvesting.

Vacuum polarization in Coulomb field revisited

DOE Office of Scientific and Technical Information (OSTI.GOV)

Zamastil, J., E-mail: zamastil@karlov.mff.cuni.cz; Šimsa, D.

2017-04-15

Simplified derivation of Wichmann–Kroll term is presented. The derivation uses two formulas for hypergeometric functions, but otherwise is elementary. It is found that Laplace transform of the vacuum charge density diverges at zero momentum transfer. This divergence has nothing to do with known ultraviolet divergence. The latter is related to the large momentum behavior of the pertinent integral, while the former to the small momentum behavior. When these divergences are removed, the energy shift caused by vacuum polarization for an ordinary hydrogen obtained here is in an exact agreement with the result obtained by Wichmann and Kroll. Also, for muonicmore » hydrogen the result obtained here reasonably agrees with that given in literature.« less

49 CFR 570.56 - Vacuum brake assist unit and vacuum brake system.

Code of Federal Regulations, 2010 CFR

2010-10-01

.... The following requirements apply to vehicles with vacuum brake assist units and vacuum brake systems. (a) Vacuum brake assist unit integrity. The vacuum brake assist unit shall demonstrate integrity as... maintained on the pedal. (1) Inspection procedure. Stop the engine and apply service brake several times to...

Value of H, space-time patterns, vacuum, matter, expansion of the Universe, alternative cosmologies

NASA Astrophysics Data System (ADS)

Gonzalez-Mestres, Luis

2017-12-01

To the experimental uncertainties on the present value H0 of the Lundmark - Lemaître-Hubble constant, fundamental theoretical uncertainties of several kinds should also be added. In standard Cosmology, consistency problems are really serious. The cosmological constant is a source of well-known diffculties while the associated dark energy is assumed to be at the origin of the observed acceleration of the expansion of the Universe. But in alternative cosmologies, possible approaches without these problems exist. An example is the pattern based on the spinorial space-time (SST) we introduced in 1996-97 where the H t = 1 relation (t = cosmic time = age of the Universe) is automatically generated by a pre-existing cosmic geometry before standard matter and conventional forces, including gravitation and relativity, are introduced. We analyse present theoretical, experimental and observational uncertainties, focusing also on the possible sources of the acceleration of the expansion of the Universe as well as on the structure of the physical vacuum and its potential cosmological role. Particular attention is given to alternative approaches to both Particle Physics and Cosmology including possible preonic constituents of the physical vacuum and associated pre-Big Bang patterns. A significant example is provided by the cosmic SST geometry together with the possibility that the expanding cosmological vacuum releases energy in the form of standard matter and dark matter, thus modifying the dependence of the matter energy density with respect to the age and size of our Universe. The SST naturally generates a new leading contribution to the value of H. If the matter energy density decreases more slowly than in standard patterns, it can naturally be at the origin of the observed acceleration of the expansion of the Universe. The mathematical and dynamical structure of standard Physics at very short distances can also be modified by an underlying preonic structure. If preons are

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

ERIC Educational Resources Information Center

Greenslade, Thomas B., Jr.

1989-01-01

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…

Boiling process modelling peculiarities analysis of the vacuum boiler

NASA Astrophysics Data System (ADS)

Slobodina, E. N.; Mikhailov, A. G.

2017-06-01

The analysis of the low and medium powered boiler equipment development was carried out, boiler units possible development directions with the purpose of energy efficiency improvement were identified. Engineering studies for the vacuum boilers applying are represented. Vacuum boiler heat-exchange processes where boiling water is the working body are considered. Heat-exchange intensification method under boiling at the maximum heat- transfer coefficient is examined. As a result of the conducted calculation studies, heat-transfer coefficients variation curves depending on the pressure, calculated through the analytical and numerical methodologies were obtained. The conclusion about the possibility of numerical computing method application through RPI ANSYS CFX for the boiling process description in boiler vacuum volume was given.

Probing the quantum vacuum with petawatt lasers

NASA Astrophysics Data System (ADS)

Hill, W. T., III; Roso, L.

2017-07-01

Due to the bosonic nature of the photon, increasing the peak intensity through a combination of raising the pulse energy and decreasing the pulse duration will pile up more and more photons within the same finite region of space. In the absence of material, this continues until the vacuum is stressed to the point of breakdown and virtual particles become real. The critical intensity where this occurs for electrons and positrons - the so-called Schwinger limit - is predicted to be ˜ 1029 W/cm2. At substantially lower intensities, however, nonlinear aspects of the quantum vacuum associated with polarization of the vacuum can be explored. These studies become viable at the petawatt level where 1023 W/cm2 and above can be reached. This is an era into which we are just embarking that will provide critical tests of QED and theories beyond the Standard Model of particle physics.

Chirped pulse inverse free-electron laser vacuum accelerator

DOEpatents

Hartemann, Frederic V.; Baldis, Hector A.; Landahl, Eric C.

2002-01-01

A chirped pulse inverse free-electron laser (IFEL) vacuum accelerator for high gradient laser acceleration in vacuum. By the use of an ultrashort (femtosecond), ultrahigh intensity chirped laser pulse both the IFEL interaction bandwidth and accelerating gradient are increased, thus yielding large gains in a compact system. In addition, the IFEL resonance condition can be maintained throughout the interaction region by using a chirped drive laser wave. In addition, diffraction can be alleviated by taking advantage of the laser optical bandwidth with negative dispersion focusing optics to produce a chromatic line focus. The combination of these features results in a compact, efficient vacuum laser accelerator which finds many applications including high energy physics, compact table-top laser accelerator for medical imaging and therapy, material science, and basic physics.

Improved Vacuum Bazooka

NASA Astrophysics Data System (ADS)

Cockman, John

2003-04-01

This apparatus is a modification to the well-known "vacuum bazooka" (PIRA 2B30.70). My vacuum bazooka is easy to construct and demonstrate, requires no precise fittings, foil, or vacuum grease, and propels ping-pong balls at a tremendous velocity!

National Enforcement Initiative: Ensuring Energy Extraction Activities Comply with Environmental Laws

EPA Pesticide Factsheets

This page describes energy extraction and EPA's goal in assuring that energy sources are developed in an environmentally protective manner. Both enforcement cases, and a map of enforcement actions are provided.

Vacuum-polarization effects in global monopole space-times

DOE Office of Scientific and Technical Information (OSTI.GOV)

Mazzitelli, F.D.; Lousto, C.O.

1991-01-15

The gravitational effect produced by a global monopole may be approximated by a solid deficit angle. As a consequence, the energy-momentum tensor of a quantum field will have a nonzero vacuum expectation value. Here we study this vacuum-polarization effect'' around the monopole. We find explicit expressions for both {l angle}{phi}{sup 2}{r angle}{sub ren} and {l angle}{ital T}{sub {mu}{nu}}{r angle}{sub ren} for a massless scalar field. The back reaction of the quantum field on the monopole metric is also investigated.

Synchronous inversion and charge extraction (SICE): a hybrid switching interface for efficient vibrational energy harvesting

NASA Astrophysics Data System (ADS)

Lallart, Mickaël; Wu, Wen-Jong; Hsieh, Yuchieh; Yan, Linjuan

2017-11-01

This paper aims at proposing an electrical interface taking advantage of nonlinear treatment for both significantly increasing the voltage of a piezoelectric device and extracting the corresponding electrostatic energy in an independent way from the connected electrical load. The principles of the proposed system lies in quickly inverting the piezoelectric voltage on each extremum (synchronized switch on inductor operations) for a given number of extremum occurrences, and then extracting the total electrostatic energy available on the piezoelectric element through the so-called synchronous electric charge extraction (SECE) for energy harvesting purpose. Compared to classical SECE approach, which consists in extracting the energy on each voltage extremum occurrence, the proposed scheme shows a significant improvement in low-coupled systems thanks to a fine control of the trade-off between voltage amplification and number of extraction events.

Coherent Wave Measurement Buoy Arrays to Support Wave Energy Extraction

NASA Astrophysics Data System (ADS)

Spada, F.; Chang, G.; Jones, C.; Janssen, T. T.; Barney, P.; Roberts, J.

2016-02-01

Wave energy is the most abundant form of hydrokinetic energy in the United States and wave energy converters (WECs) are being developed to extract the maximum possible power from the prevailing wave climate. However, maximum wave energy capture is currently limited by the narrow banded frequency response of WECs as well as extended protective shutdown requirements during periods of large waves. These limitations must be overcome in order to maximize energy extraction, thus significantly decreasing the cost of wave energy and making it a viable energy source. Techno-economic studies of several WEC devices have shown significant potential to improve wave energy capture efficiency through operational control strategies that incorporate real-time information about local surface wave motions. Integral Consulting Inc., with ARPA-E support, is partnering with Sandia National Laboratories and Spoondrift LLC to develop a coherent array of wave-measuring devices to relay and enable the prediction of wave-resolved surface dynamics at a WEC location ahead of real time. This capability will provide necessary information to optimize power production of WECs through control strategies, thereby allowing for a single WEC design to perform more effectively across a wide range of wave environments. The information, data, or work presented herein was funded in part by the Advanced Research Projects Agency-Energy (ARPA-E), U.S. Department of Energy, under Award Number DE-AR0000514.

CFD Analysis of Evaporation-Condensation Phenomenon In an Evaporation Chamber of Natural Vacuum Solar Desalination

NASA Astrophysics Data System (ADS)

Ambarita, H.; Ronowikarto, A. D.; Siregar, R. E. T.; Setyawan, E. Y.

2018-01-01

Desalination technologies is one of solutions for water scarcity. With using renewable energy, like solar energy, wind energy, and geothermal energy, expected will reduce the energy demand. This required study on the modeling and transport parameters determination of natural vacuum solar desalination by using computational fluid dynamics (CFD) method to simulate the model. A three-dimensional case, two-phase model was developed for evaporation-condensation phenomenon in natural vacuum solar desalination. The CFD simulation results were compared with the avalaible experimental data. The simulation results shows inthat there is a phenomenon of evaporation-condensation in an evaporation chamber. From the simulation, the fresh water productivity is 2.21 litre, and from the experimental is 2.1 litre. This study shows there’s an error of magnitude 0.4%. The CFD results also show that, vacuum pressure will degrade the saturation temperature of sea water.

Majorana neutrino and the vacuum of Bogoliubov quasiparticle

NASA Astrophysics Data System (ADS)

Fujikawa, Kazuo

2018-06-01

The Lagrangian of the seesaw mechanism is C violating but the same Lagrangian when re-written in terms of Majorana neutrinos is manifestly C invariant. To resolve this puzzling feature, a relativistic analogue of Bogoliubov transformation, which preserves CP but explicitly breaks C and P separately, was introduced together with the notions of a Bogoliubov quasiparticle and an analogue of the energy gap in BCS theory. The idea of Majorana neutrino as Bogoliubov quasiparticle was then suggested. In this paper, we study the vacuum structure of the Bogoliubov quasiparticle which becomes heavy by absorbing the C-breaking. By treating an infinitesimally small C violating term as an analogue of the chiral symmetry breaking nucleon mass in the model of Nambu and Jona-Lasinio, we construct an explicit form of the vacuum of the Bogoliubov quasiparticle which defines Majorana neutrinos in seesaw mechanism. The vacuum of the Bogoliubov quasiparticle thus constructed has an analogous condensate structure as the vacuum of the quasiparticle (nucleon) in the Nambu-Jona-Lasinio model.

The Classical Vacuum.

ERIC Educational Resources Information Center

Boyer, Timothy H.

1985-01-01

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

The vacuum system reform and test of the super-critical 600mw unit

NASA Astrophysics Data System (ADS)

Yan, Tao; Wan, Zhonghai; Lu, Jin; Chen, Wen; Cai, Wen

2017-11-01

The deficiencies of the designed vacuum system of the super-critical unit is pointed out in this paper, and then it is reformed by the steam ejector. The experimental results show that the vacuum of the condenser can be improved, the coal consumption can be reduced and the plant electricity consumption can be lowered dramatically at a small cost of the steam energy consumption. Meanwhile, the water-ring vacuum pumps cavitation problems can be solved.

Vacuum electron acceleration by coherent dipole radiation

DOE Office of Scientific and Technical Information (OSTI.GOV)

Troha, A.L.; Van Meter, J.R.; Landahl, E.C.

1999-07-01

The validity of the concept of laser-driven vacuum acceleration has been questioned, based on an extrapolation of the well-known Lawson-Woodward theorem, which stipulates that plane electromagnetic waves cannot accelerate charged particles in vacuum. To formally demonstrate that electrons can indeed be accelerated in vacuum by focusing or diffracting electromagnetic waves, the interaction between a point charge and coherent dipole radiation is studied in detail. The corresponding four-potential exactly satisfies both Maxwell{close_quote}s equations and the Lorentz gauge condition everywhere, and is analytically tractable. It is found that in the far-field region, where the field distribution closely approximates that of a planemore » wave, we recover the Lawson-Woodward result, while net acceleration is obtained in the near-field region. The scaling of the energy gain with wave-front curvature and wave amplitude is studied systematically. {copyright} {ital 1999} {ital The American Physical Society}« less

Energy Extraction from a Slider-Crank Wave Energy under Irregular Wave Conditions: Preprint

DOE Office of Scientific and Technical Information (OSTI.GOV)

Sang, Yuanrui; Karayaka, H. Bora; Yan, Yanjun

2015-08-24

A slider-crank wave energy converter (WEC) is a novel energy conversion device. It converts wave energy into electricity at a relatively high efficiency, and it features a simple structure. Past analysis on this particular WEC has been done under regular sinusoidal wave conditions, and suboptimal energy could be achieved. This paper presents the analysis of the system under irregular wave conditions; a time-domain hydrodynamics model is adopted and a rule-based control methodology is introduced to better serve the irregular wave conditions. Results from the simulations show that the performance of the system under irregular wave conditions is different from thatmore » under regular sinusoidal wave conditions, but a reasonable amount of energy can still be extracted.« less

Energy Extraction from a Slider-Crank Wave Energy Converter under Irregular Wave Conditions

DOE Office of Scientific and Technical Information (OSTI.GOV)

Sang, Yuanrui; Karayaka, H. Bora; Yan, Yanjun

2015-10-19

A slider-crank wave energy converter (WEC) is a novel energy conversion device. It converts wave energy into electricity at a relatively high efficiency, and it features a simple structure. Past analysis on this particular WEC has been done under regular sinusoidal wave conditions, and suboptimal energy could be achieved. This paper presents the analysis of the system under irregular wave conditions; a time-domain hydrodynamics model is adopted and a rule-based control methodology is introduced to better serve the irregular wave conditions. Results from the simulations show that the performance of the system under irregular wave conditions is different from thatmore » under regular sinusoidal wave conditions, but a reasonable amount of energy can still be extracted.« less

Germanium detector vacuum encapsulation

NASA Technical Reports Server (NTRS)

Madden, N. W.; Malone, D. F.; Pehl, R. H.; Cork, C. P.; Luke, P. N.; Landis, D. A.; Pollard, M. J.

1991-01-01

This paper describes an encapsulation technology that should significantly improve the viability of germanium gamma-ray detectors for a number of important applications. A specialized vacuum chamber has been constructed in which the detector and the encapsulating module are processed in high vacuum. Very high vacuum conductance is achieved within the valveless encapsulating module. The detector module is then sealed without breaking the chamber vacuum. The details of the vacuum chamber, valveless module, processing, and sealing method are presented.

Energy, Vacuum, Gas Fueling, and Security Systems for the Spherical Tokamak MEDUSA-CR

NASA Astrophysics Data System (ADS)

Gonzalez, Jeferson; Soto, Christian; Carvajal, Johan; Ribeiro, Celso

2013-10-01

The former spherical tokamak (ST) MEDUSA (Madison EDUcation Small Aspect.ratio tokamak, R < 0.14 m, a < 0.10 m, BT < 0.5 T, Ip < 40 kA, 3 ms pulse) is being recommissioned in Costa Rica Institute of Technology. The main objectives of the MEDUSA-CR project are training and to clarify several issues in relevant physics for conventional and mainly STs, including beta studies in bean-shaped ST plasmas, transport, heating and current drive via Alfvén wave, and natural divertor STs with ergodic magnetic limiter. We present here the energy, vacuum, gas fueling, and security systems for MEDUSA-CR device. The interface with the control and data acquisition systems based on National Instruments (NI) software (LabView) and hardware (on loan to our laboratory via NI-Costa Rica) are also presented. VIE-ITCR, IAEA-CRP contract 17592, National Instruments of Costa Rica.

Possible form of vacuum deformation by heavy particles

NASA Technical Reports Server (NTRS)

Mackenzie, R.; Wilczek, F.; Zee, A.

1984-01-01

The possibility is discussed that the lowest-energy state for certain quantum numbers involves a Higgs field polarized into a skyrmion-type configuration. In some models a new type of vacuum instability arises. Phenomenological consequences are indicated schematically.

Development of High Interruption Capability Vacuum Circuit Breaker -Technology of Vacuum Arc Control-

NASA Astrophysics Data System (ADS)

Niwa, Yoshimitsu; Kaneko, Eiji

Vacuum circuit breakers (VCB) have been widely used for power distribution systems. Vacuum Interrupters, which are the current interruption unit, have been increased its interruption capability with the development of vacuum arc control technology by magnetic field. There are three major type electrodes: disk shaped electrodes, radial magnetic field electrodes, axial magnetic field (AMF) electrodes. In the disk shaped electrode, the vacuum arc between the electrodes is not controlled. In the AMF electrode, the vacuum arc is diffused and stabilized by an axial magnetic field, which is parallel to the arc current. In the last type of electrodes, the vacuum arc column is rotated by magnetic force generated by the current flowing in the electrodes. The interruption current and the voltage of one break VCB is increased to 100 kA, 144 kV respectively. This paper describes basic configurations and functions of VCB, vacuum arc control technology in vacuum interrupters, recent researches and applications of VCB.

Intensity and Energy Level Analysis of the Vacuum Ultraviolet Spectrum of Four Times Ionize Nickel (Ni V)

NASA Astrophysics Data System (ADS)

Ward, Jacob Wolfgang; Nave, Gillian

2016-01-01

Recent measurements of four times ionized iron and nickel (Fe V & Ni V) wavelengths in the vacuum ultraviolet (VUV) have been taken using the National Institute for Standards and Technology (NIST) Normal Incidence Vacuum Spectrograph (NIVS) with a sliding spark light source with invar electrodes. The wavelengths observed in those measurements make use of high resolution photographic plates with the majority of observed lines having uncertainties of approximately 3mÅ. In addition to observations made with photographic plates, the same wavelength region was observed with phosphor image plates, which have been demonstrated to be accurate as a method of intensity calibration when used with a deuterium light source. This work will evaluate the use of phosphor image plates and deuterium lamps as an intensity calibration method for the Ni V spectrum in the 1200-1600Å region of the VUV. Additionally, by pairing the observed wavelengths of Ni V with accurate line intensities, it is possible to create an energy level optimization for Ni V providing high accuracy Ritz wavelengths. This process has previously been applied to Fe V and produced Ritz wavelengths that agreed with the above experimental observations.

Dynamical dark energy vs. Λ = const in light of observations

NASA Astrophysics Data System (ADS)

Solà Peracaula, Joan; de Cruz Pérez, Javier; Gómez-Valent, Adrià

2018-02-01

After about two decades of the first observational papers confirming the accelerated expansion of the universe, we are still facing the question whether the cause of it is a rigid cosmological constant Λ-term or a mildly evolving dynamical dark energy (DDE). While studies focusing mainly on CMB measurements do not perceive signs of physics beyond the ΛCDM, in this work we show that if we take a large string SNIa+BAO+H(z)+LSS+CMB of modern cosmological observations, in which not only the CMB but also a rich sample of large-scale structure formation data are included, one can extract ∼3.3σ signs of DDE using a simple XCDM parameterization. These signs can be enhanced up to near 3.8σ in the context of the running vacuum model (RVM), in which the vacuum energy density is in interaction with dark matter. Recently, the RVM has been shown to provide an efficient and economical solution to the σ8 -tension, which is one of the intriguing phenomenological problems that has not been possible to solve within the ΛCDM so far. This fact contributes to strengthen the possibility that dynamical vacuum energy, or in general DDE, could be presently favored by the observations.

Vacuum-induced coherence in quantum dot systems

NASA Astrophysics Data System (ADS)

Sitek, Anna; Machnikowski, Paweł

2012-11-01

We present a theoretical study of vacuum-induced coherence in a pair of vertically stacked semiconductor quantum dots. The process consists in a coherent excitation transfer from a single-exciton state localized in one dot to a delocalized state in which the exciton occupation gets trapped. We study the influence of the factors characteristic of quantum dot systems (as opposed to natural atoms): energy mismatch, coupling between the single-exciton states localized in different dots, and different and nonparallel dipoles due to sub-band mixing, as well as coupling to phonons. We show that the destructive effect of the energy mismatch can be overcome by an appropriate interplay of the dipole moments and coupling between the dots which allows one to observe the trapping effect even in a structure with technologically realistic energy splitting of the order of milli-electron volts. We also analyze the impact of phonon dynamics on the occupation trapping and show that phonon effects are suppressed in a certain range of system parameters. This analysis shows that the vacuum-induced coherence effect and the associated long-living trapped excitonic population can be achieved in quantum dots.

Vacuum system design and tritium inventory for the TFTR charge exchange diagnostic

DOE Office of Scientific and Technical Information (OSTI.GOV)

Medley, S.S.

The charge exchange diagnostic for the TFTR is comprised of two analyzer systems which contain a total of twenty independent mass/energy analyzers and one diagnostic neutral beam tentatively rated at 80 keV, 15 A. The associated vacuum systems were analyzed using the Vacuum System Transient Simulator (VSTS) computer program which models the transient transport of multi-gas species through complex networks of ducts, valves, traps, vacuum pumps, and other related vacuum system components. In addition to providing improved design performance at reduced cost, the analysis yields estimates for the exchange of tritium from the torus to the diagnostic components and ofmore » the diagnostic working gases to the torus.« less

Quantum Mechanics, vacuum, particles, Gödel-Cohen incompleteness and the Universe

NASA Astrophysics Data System (ADS)

Gonzalez-Mestres, Luis

2017-12-01

Are the standard laws of Physics really fundamental principles? Does the physical vacuum have a more primordial internal structure? Are quarks, leptons, gauge bosons… ultimate elementary objects? These three basic questions are actually closely related. If the deep vacuum structure and dynamics turn out to be less trivial than usually depicted, the conventional "elementary" particles will most likely be excitations of such a vacuum dynamics that remains by now unknown. We then expect relativity and quantum mechanics to be low-energy limits of a more fundamental dynamical pattern that generates them at a deeper level. It may even happen that vacuum drives the expansion of the Universe from its own inner dynamics. Inside such a vacuum structure, the speed of light would not be the critical speed for vacuum constituents and propagating signals. The natural scenario would be the superbradyon (superluminal preon) pattern we postulated in 1995, with a new critical speed cs much larger than the speed of light c just as c is much larger than the speed of sound. Superbradyons are assumed to be the bradyons of a super-relativity associated to cs (a Lorentz invariance with cs as the critical speed). Similarly, the standard relativistic space-time with four real coordinates would not necessarily hold beyond low-energy and comparatively local distance scales. Instead, the spinorial space-time (SST) with two complex coordinates we introduced in 1996-97 may be the suitable one to describe the internal structure of vacuum and standard "elementary" particles and, simultaneously, Cosmology at very large distance scales. If the constituents of the preonic vacuum are superluminal, quantum entanglement appears as a natural property provided cs ≫ c . The value of cs can even be possibly found experimentally by studying entanglement at large distances. It is not excluded that preonic constituents of vacuum can exist in our Universe as free particles ("free" superbradyons), in which

Complex technology of vacuum-arc processing of structural material surface

NASA Astrophysics Data System (ADS)

Arustamov, V. N.; Ashurov, Kh. B.; Kadyrov, Kh. Kh.; Khudoikulov, I. Kh.

2015-08-01

The development of environmentally friendly and energy-resource-saving technologies based on vacuum arc discharge is a topical problem in science and engineering. In view of their unique properties, cathode spots of a vacuum arc induce cleaning of the surface of an article (cathode) from various contaminations and pulsed thermal action on the surface layers. These processes occur in complex with vacuum-arc deposition of coatings in the same technological cycle, which makes it possible to considerably increase the efficiency of methods for changing physical, mechanical, and chemical properties of the surface of steel articles, which considerably increase their service life. Analysis of the formation of the temperature regime of the surface during vacuum arc action and of the parameters of the deposited coating will make it possible to optimize the regimes of complex treatment of the surfaces of articles and is of considerable theoretical and practical importance.

Well-posedness of the plasma-vacuum interface problem

NASA Astrophysics Data System (ADS)

Secchi, Paolo; Trakhinin, Yuri

2014-01-01

We consider the free-boundary problem for the plasma-vacuum interface in ideal compressible magnetohydrodynamics (MHD). In the plasma region the flow is governed by the usual compressible MHD equations, while in the vacuum region we consider the pre-Maxwell dynamics for the magnetic field. At the free interface, driven by the plasma velocity, the total pressure is continuous and the magnetic field on both sides is tangent to the boundary. The plasma-vacuum system is not isolated from the outside world, because of a given surface current on the fixed boundary that forces oscillations. Under a suitable stability condition satisfied at each point of the initial interface, stating that the magnetic fields on either side of the interface are not collinear, we show the existence and uniqueness of the solution to the nonlinear plasma-vacuum interface problem in suitable anisotropic Sobolev spaces. The proof is based on the results proved in the companion paper (Secchi and Trakhinin 2013 Interfaces Free Boundaries 15 323-57), about the well-posedness of the homogeneous linearized problem and the proof of a basic a priori energy estimate. The proof of the resolution of the nonlinear problem given in the present paper follows from the analysis of the elliptic system for the vacuum magnetic field, a suitable tame estimate in Sobolev spaces for the full linearized equations, and a Nash-Moser iteration.

Big Bang Titanic: New Dark Energy (Vacuum Gravity) Cosmic Model Emerges Upon Falsification of The Big Bang By Disproof of Its Central Assumptions

NASA Astrophysics Data System (ADS)

Gentry, Robert

2011-04-01

Physicists who identify the big bang with the early universe should have first noted from Hawking's A Brief History of Time, p. 42, that he ties Hubble's law to Doppler shifts from galaxy recession from a nearby center, not to bb's unvalidated and thus problematical expansion redshifts. Our PRL submission LJ12135 describes such a model, but in it Hubble's law is due to Doppler and vacuum gravity effects, the 2.73K CBR is vacuum gravity shifted blackbody cavity radiation from an outer galactic shell, and its (1 + z)-1 dilation and (M,z) relations closely fit high-z SNe Ia data; all this strongly implies our model's vacuum energy is the elusive dark energy. We also find GPS operation's GR effects falsify big bang's in-flight expansion redshift paradigm, and hence the big bang, by showing λ changes occur only at emission. Surprisingly we also discover big bang's CBR prediction is T < 2x10-8 K, not the observed 2.73K. So instead of the 2.73K affirming the big bang as cosmologists claim, it actually disproves it, to which the DAE's response is most enigmatic -- namely, CBR photons expand dλ/dt > 0, while galactic photons shrink dλ/dt < 0. Contrary to a PRL editor's claim, the above results show LJ12135 fits PRL guidelines for papers that replace established theories. For details see alphacosmos.net.

Velocity map imaging using an in-vacuum pixel detector.

PubMed

Gademann, Georg; Huismans, Ymkje; Gijsbertsen, Arjan; Jungmann, Julia; Visschers, Jan; Vrakking, Marc J J

2009-10-01

The use of a new type in-vacuum pixel detector in velocity map imaging (VMI) is introduced. The Medipix2 and Timepix semiconductor pixel detectors (256 x 256 square pixels, 55 x 55 microm2) are well suited for charged particle detection. They offer high resolution, low noise, and high quantum efficiency. The Medipix2 chip allows double energy discrimination by offering a low and a high energy threshold. The Timepix detector allows to record the incidence time of a particle with a temporal resolution of 10 ns and a dynamic range of 160 micros. Results of the first time application of the Medipix2 detector to VMI are presented, investigating the quantum efficiency as well as the possibility to operate at increased background pressure in the vacuum chamber.

Progress on the Design of the Storage Ring Vacuum System for the Advanced Photon Source Upgrade Project

DOE Office of Scientific and Technical Information (OSTI.GOV)

Stillwell, B.; Billett, B.; Brajuskovic, B.

2017-06-20

Recent work on the design of the storage ring vacuum system for the Advanced Photon Source Upgrade project (APS-U) includes: revising the vacuum system design to accommodate a new lattice with reverse bend magnets, modifying the designs of vacuum chambers in the FODO sections for more intense incident synchrotron radiation power, modifying the design of rf-shielding bellows liners for better performance and reliability, modifying photon absorber designs to make better use of available space, and integrated planning of components needed in the injection, extraction and rf cavity straight sections. An overview of progress in these areas is presented.

Intrapartum translabial ultrasound with pushing used to predict the difficulty in vacuum-assisted delivery of fetuses in non-occiput posterior position.

PubMed

Antonio Sainz, José; Borrero, Carlota; Aquise, Adriana; García-Mejido, José Antonio; Gutierrez, Laura; Fernández-Palacín, Ana

2016-10-01

Our aim is to evaluate the capacity of intrapartum translabial ultrasound (ITU) with pushing in the prediction of difficulty of fetal extraction in vacuum assisted deliveries. Prospective, observational study performed (2/2015-8/2015) on 75 nulliparous women, ≥37 weeks with singleton pregnancies at full dilatation who had ITU-with-pushing performed, previous to vacuum-placement for fetal extraction. Working on the translabial sagittal-plane, we assessed: Angle-Progression (AoP), Progression-Distance (PD) and Head-Direction (HD); in the axial plane we evaluated: Midline-Angle (MLA) and Head-Perineum-Distance (HPD). Vacuum extractions were classified as easy-difficulty (ED) (≤3 vacuum-pulls), difficult-unsuccessful (DD) (>3 vacuum-pulls). We did not assess occipito-posterior-presentations. Seventy nulliparous were studied (44-ED,26-DD). We observed no differences in obstetric, neonatal or intrapartum characteristics between the two study groups, with the following exceptions: newborn weight (3272 ± 438 g versus 3540 ± 372 g; p = 0.011) and number of vacuum-pulls (1.4-ED-vs-4.4-DD; p < 0.0005). AoP-pushing was 143.9° ± 14.6° in ED and 115.1°± 12.9° in DD (p < 0.0005); Head-Up was 79.5% versus 38.4% (p < 0.0005); PD-Pushing was 42.7 ± 11.3 mm versus 30.4 ± 9.8 mm (p < 0.0005); MLA-Pushing was 27.6°± 26.6° versus 57.5°±26.5°(p=0.025); HPD-Pushing was 40.8 ± 10.0 mm versus 47.4 ± 10.9 mm (p = 0.039). We identified that the presence of an AoP-Pushing > 128° predicts an Easy-Vacuum-Delivery (≤3 Vacuum-Pulls) in  >85% of cases (Sen 80%-FPR 9.3%).

Modified coulomb law in a strongly magnetized vacuum.

PubMed

Shabad, Anatoly E; Usov, Vladimir V

2007-05-04

We study the electric potential of a charge placed in a strong magnetic field B>B(0) approximately 4.4x10(13) G, as modified by the vacuum polarization. In such a field the electron Larmour radius is much less than its Compton length. At the Larmour distances a scaling law occurs, with the potential determined by a magnetic-field-independent function. The scaling regime implies short-range interaction, expressed by the Yukawa law. The electromagnetic interaction regains its long-range character at distances larger than the Compton length, the potential decreasing across B faster than along. Correction to the nonrelativistic ground-state energy of a hydrogenlike atom is found. In the limit B = infinity, the modified potential becomes the Dirac delta function plus a regular background. With this potential the ground-state energy is finite--the best pronounced effect of the vacuum polarization.

Vacuum quantum stress tensor fluctuations: A diagonalization approach

NASA Astrophysics Data System (ADS)

Schiappacasse, Enrico D.; Fewster, Christopher J.; Ford, L. H.

2018-01-01

Large vacuum fluctuations of a quantum stress tensor can be described by the asymptotic behavior of its probability distribution. Here we focus on stress tensor operators which have been averaged with a sampling function in time. The Minkowski vacuum state is not an eigenstate of the time-averaged operator, but can be expanded in terms of its eigenstates. We calculate the probability distribution and the cumulative probability distribution for obtaining a given value in a measurement of the time-averaged operator taken in the vacuum state. In these calculations, we study a specific operator that contributes to the stress-energy tensor of a massless scalar field in Minkowski spacetime, namely, the normal ordered square of the time derivative of the field. We analyze the rate of decrease of the tail of the probability distribution for different temporal sampling functions, such as compactly supported functions and the Lorentzian function. We find that the tails decrease relatively slowly, as exponentials of fractional powers, in agreement with previous work using the moments of the distribution. Our results lend additional support to the conclusion that large vacuum stress tensor fluctuations are more probable than large thermal fluctuations, and may have observable effects.

Numerical Study on Radiation Effects to Evaporator in Natural Vacuum Solar Desalination System

NASA Astrophysics Data System (ADS)

Siregar, R. E. T.; Ronowikarto, A. D.; Setyawan, E. Y.; Ambarita, H.

2018-01-01

The need for clean water is increasing day by day due to the increasing factor of living standard of mankind, hence designed natural vacuum solar desalination. The natural vacuum Solar desalination is studied experimentally. A small-scale natural vacuum desalination study consists of evaporator and condenser as the main components designed and manufactured. To transfer heat from the solar collector into the evaporator, the fluid transfer system uses a pump powered by a solar cell. Thus, solar collectors are called hybrid solar collectors. The main purpose of this exposure is to know the characteristics of the radiation effects on incoming energy on the evaporator during the process. This system is tested by exposing the unit to the solar radiation in the 4th floor building in Medan. The experiment was conducted from 8.00 to 16.00 local time. The results show that natural vacuum solar desalination with hybrid solar collectors can be operated perfectly. If the received radiation is high, then the incoming energy received by the evaporator will also be high. From measurements with HOBO microstation, obtained the highest radiation 695.6 W/m2, and the calculation result of incoming energy received evaporator obtained highest result 1807.293 W.

Vacuum polarization and Hawking radiation

NASA Astrophysics Data System (ADS)

Rahmati, Shohreh

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.

Maximum wind energy extraction strategies using power electronic converters

NASA Astrophysics Data System (ADS)

Wang, Quincy Qing

2003-10-01

This thesis focuses on maximum wind energy extraction strategies for achieving the highest energy output of variable speed wind turbine power generation systems. Power electronic converters and controls provide the basic platform to accomplish the research of this thesis in both hardware and software aspects. In order to send wind energy to a utility grid, a variable speed wind turbine requires a power electronic converter to convert a variable voltage variable frequency source into a fixed voltage fixed frequency supply. Generic single-phase and three-phase converter topologies, converter control methods for wind power generation, as well as the developed direct drive generator, are introduced in the thesis for establishing variable-speed wind energy conversion systems. Variable speed wind power generation system modeling and simulation are essential methods both for understanding the system behavior and for developing advanced system control strategies. Wind generation system components, including wind turbine, 1-phase IGBT inverter, 3-phase IGBT inverter, synchronous generator, and rectifier, are modeled in this thesis using MATLAB/SIMULINK. The simulation results have been verified by a commercial simulation software package, PSIM, and confirmed by field test results. Since the dynamic time constants for these individual models are much different, a creative approach has also been developed in this thesis to combine these models for entire wind power generation system simulation. An advanced maximum wind energy extraction strategy relies not only on proper system hardware design, but also on sophisticated software control algorithms. Based on literature review and computer simulation on wind turbine control algorithms, an intelligent maximum wind energy extraction control algorithm is proposed in this thesis. This algorithm has a unique on-line adaptation and optimization capability, which is able to achieve maximum wind energy conversion efficiency through

Enhanced Photocatalytic Activity of Vacuum-activated TiO2 Induced by Oxygen Vacancies.

PubMed

Dong, Guoyan; Wang, Xin; Chen, Zhiwu; Lu, Zhenya

2018-05-01

TiO 2 (Degussa P25) photocatalysts harboring abundant oxygen vacancies (Vacuum P25) were manufactured using a simple and economic Vacuum deoxidation process. Control experiments showed that temperature and time of vacuum deoxidation had a significant effect on Vacuum P25 photocatalytic activity. After 240 min of visible light illumination, the optimal Vacuum P25 photocatalysts (vacuum deoxidation treated at 330 °C for 3 h) reach as high as 94% and 88% of photodegradation efficiency for rhodamine B (RhB) and tetracycline, respectively, which are around 4.5 and 4.9 times as that of pristine P25. The XPS, PL and EPR analyses indicated that the oxygen vacancies were produced in the Vacuum P25 during the vacuum deoxidation process. The oxygen vacancy states can produce vacancy energy level located below the conduction band minimum, which resulting in the bandgap narrowing, thus extending the photoresponse wavelength range of Vacuum P25. The positron annihilation analysis indicated that the concentrations ratio of bulk and surface oxygen vacancies could be adjusted by changing the vacuum deoxidation temperature and time. Decreasing the ratio of bulk and surface oxygen vacancies was shown to improve photogenerated electron-hole pair separation efficiency, which leads to an obvious enhancement of the visible photocatalytic activities of Vacuum P25. © 2017 The American Society of Photobiology.

Measurement of the vacuum-ultraviolet absorption spectrum of low-k dielectrics using X-ray reflectivity

NASA Astrophysics Data System (ADS)

Choudhury, F. A.; Nguyen, H. M.; King, S. W.; Lee, C. H.; Lin, Y. H.; Fung, H. S.; Chen, C. C.; Li, W.; Benjamin, D.; Blatz, J. M.; Nishi, Y.; Shohet, J. L.

2018-02-01

During plasma processing, low-k dielectrics are exposed to high levels of vacuum ultraviolet (VUV) radiation that can cause severe damage to dielectric materials. The degree and nature of VUV-induced damage depend on the VUV photon energies and fluence. In this work, we examine the VUV-absorption spectrum of low-k organosilicate glass using specular X-ray reflectivity (XRR). Low-k SiCOH films were exposed to synchrotron VUV radiation with energies ranging from 7 to 21 eV, and the density vs. depth profile of the VUV-irradiated films was extracted from fitting the XRR experimental data. The results show that the depth of the VUV-induced damage layer is a function of the photon energy. Between 7 and 11 eV, the depth of the damaged layer decreases sharply from 110 nm to 60 nm and then gradually increases to 85 nm at 21 eV. The maximum VUV absorption in low-k films occurs between 11 and 15 eV. The depth of the damaged layer was found to increase with film porosity.

Radiation hard vacuum switch

DOEpatents

Boettcher, Gordon E.

1990-01-01

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

Radiation hard vacuum switch

DOEpatents

Boettcher, Gordon E.

1990-03-06

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

Experimental investigation on the energy deposition and expansion rate under the electrical explosion of aluminum wire in vacuum

DOE Office of Scientific and Technical Information (OSTI.GOV)

Shi, Zongqian; Wang, Kun; Shi, Yuanjie

Experimental investigations on the electrical explosion of aluminum wire using negative polarity current in vacuum are presented. Current pulses with rise rates of 40 A/ns, 80 A/ns, and 120 A/ns are generated for investigating the influence of current rise rate on energy deposition. Experimental results show a significant increase of energy deposition into the wire before the voltage breakdown with the increase of current rise rate. The influence of wire dimension on energy deposition is investigated as well. Decreasing the wire length allows more energy to be deposited into the wire. The energy deposition of a 0.5 cm-long wire explosion ismore » ∼2.5 times higher than the energy deposition of a 2 cm-long wire explosion. The dependence of the energy deposition on wire diameter demonstrates a maximum energy deposition of 2.7 eV/atom with a diameter of ∼18 μm. Substantial increase in energy deposition is observed in the electrical explosion of aluminum wire with polyimide coating. A laser probe is applied to construct the shadowgraphy, schlieren, and interferometry diagnostics. The morphology and expansion trajectory of exploding products are analyzed based on the shadowgram. The interference phase shift is reconstructed from the interferogram. Parallel dual wires are exploded to estimate the expansion velocity of the plasma shell.« less

Measurements on the gas desorption yield of the oxygen-free copper irradiated with low-energy Xe10+ and O+

NASA Astrophysics Data System (ADS)

Dong, Z. Q.; Li, P.; Yang, J. C.; Yuan, Y. J.; Xie, W. J.; Zheng, W. H.; Liu, X. J.; Chang, J. J.; Luo, C.; Meng, J.; Wang, J. C.; Wang, Y. M.; Yin, Y.; Chai, Z.

2017-10-01

Heavy ion beam lost on the accelerator vacuum wall will release quantity of gas molecules and make the vacuum system deteriorate seriously. This phenomenon is called dynamic vacuum effect, observed at CERN, GSI and BNL, leading to the decrease of beam lifetime when increasing beam intensity. Heavy ion-induced gas desorption, which results in dynamic vacuum effect, becomes one of the most important problems for future accelerators proposed to operate with intermediate charge state beams. In order to investigate the mechanism of this effect and find the solution method for the IMP future project High Intensity heavy-ion Accelerator Facility (HIAF), which is designed to extract 1 × 1011 uranium particles with intermediate charge state per cycle, two dedicated experiment setups have been installed at the beam line of the CSR and the 320 kV HV platform respectively. Recently, experiment was performed at the 320 kV HV platform to study effective gas desorption with oxygen-free copper target irradiated with continuous Xe10+ beam and O+ beam in low energy regime. Gas desorption yield in this energy regime was calculated and the link between gas desorption and electronic energy loss in Cu target was proved. These results will be used to support simulations about dynamic vacuum effect and optimizations about efficiency of collimators to be installed in the HIAF main synchrotron BRing, and will also provide guidance for future gas desorption measurements in high energy regime.

Production of Magnesium by Vacuum Aluminothermic Reduction with Magnesium Aluminate Spinel as a By-Product

NASA Astrophysics Data System (ADS)

Wang, Yaowu; You, Jing; Peng, Jianping; Di, Yuezhong

2016-06-01

The Pidgeon process currently accounts for 85% of the world's magnesium production. Although the Pidgeon process has been greatly improved over the past 10 years, such production still consumes much energy and material and creates much pollution. The present study investigates the process of producing magnesium by employing vacuum aluminothermic reduction and by using magnesite as material and obtaining magnesium aluminate spinel as a by-product. The results show that compared with the Pidgeon process, producing magnesium by vacuum aluminothermic reduction can save materials by as much as 50%, increase productivity up to 100%, and save energy by more than 50%. It can also reduce CO2 emission by up to 60% and realize zero discharge of waste residue. Vacuum aluminothermic reduction is a highly efficient, low-energy-consumption, and environmentally friendly method of producing magnesium.

A novel dehydration technique for carrot slices implementing ultrasound and vacuum drying methods.

PubMed

Chen, Zhi-Gang; Guo, Xiao-Yu; Wu, Tao

2016-05-01

A novel drying technique using a combination of ultrasound and vacuum dehydration was developed to shorten the drying time and improve the quality of carrot slices. Carrot slices were dried with ultrasonic vacuum (USV) drying and vacuum drying at 65 °C and 75 °C. The drying rate was significantly influenced by the drying techniques and temperatures. Compared with vacuum drying, USV drying resulted in a 41-53% decrease in the drying time. The drying time for the USV and vacuum drying techniques at 75 °C was determined to be 140 and 340 min for carrot slices, respectively. The rehydration potential, nutritional value (retention of β-carotene and ascorbic acid), color, and textural properties of USV-dried carrot slices are predominately better compared to vacuum-dried carrot slices. Moreover, lower energy consumption was used in the USV technique. The drying data (time versus moisture ratio) were successfully fitted to Wang and Singh model. Copyright © 2015. Published by Elsevier B.V.

Vacuum Nanohole Array Embedded Phosphorescent Organic Light Emitting Diodes

PubMed Central

Jeon, Sohee; Lee, Jeong-Hwan; Jeong, Jun-Ho; Song, Young Seok; Moon, Chang-Ki; Kim, Jang-Joo; Youn, Jae Ryoun

2015-01-01

Light extraction from organic light-emitting diodes that utilize phosphorescent materials has an internal efficiency of 100% but is limited by an external quantum efficiency (EQE) of 30%. In this study, extremely high-efficiency organic light emitting diodes (OLEDs) with an EQE of greater than 50% and low roll-off were produced by inserting a vacuum nanohole array (VNHA) into phosphorescent OLEDs (PhOLEDs). The resultant extraction enhancement was quantified in terms of EQE by comparing experimentally measured results with those produced from optical modeling analysis, which assumes the near-perfect electric characteristics of the device. A comparison of the experimental data and optical modeling results indicated that the VNHA extracts the entire waveguide loss into the air. The EQE obtained in this study is the highest value obtained to date for bottom-emitting OLEDs. PMID:25732061

Matter-antimatter asymmetry induced by a running vacuum coupling

NASA Astrophysics Data System (ADS)

Lima, J. A. S.; Singleton, D.

2017-12-01

We show that a CP-violating interaction induced by a derivative coupling between the running vacuum and a non-conserving baryon current may dynamically break CPT and trigger baryogenesis through an effective chemical potential. By assuming a non-singular class of running vacuum cosmologies which provides a complete cosmic history (from an early inflationary de Sitter stage to the present day quasi-de Sitter acceleration), it is found that an acceptable baryon asymmetry is generated for many different choices of the model parameters. It is interesting that the same ingredient (running vacuum energy density) addresses several open cosmological questions/problems: avoids the initial singularity, provides a smooth exit for primordial inflation, alleviates both the coincidence and the cosmological constant problems, and, finally, is also capable of explaining the generation of matter-antimatter asymmetry in the very early Universe.

EXPLORING PROOF OF CONCEPT IN OCEAN CURRENT ENERGY EXTRACTION

EPA Science Inventory

The small-scale OCEE is expected to yield a power density similar to that of an average wind turbine of comparable size. The project will result in specifications for materials, turbine geometries and turbine location/orientation that will extract the most energy from ocean curre...

Velocity map imaging using an in-vacuum pixel detector

DOE Office of Scientific and Technical Information (OSTI.GOV)

Gademann, Georg; Huismans, Ymkje; Gijsbertsen, Arjan

The use of a new type in-vacuum pixel detector in velocity map imaging (VMI) is introduced. The Medipix2 and Timepix semiconductor pixel detectors (256x256 square pixels, 55x55 {mu}m{sup 2}) are well suited for charged particle detection. They offer high resolution, low noise, and high quantum efficiency. The Medipix2 chip allows double energy discrimination by offering a low and a high energy threshold. The Timepix detector allows to record the incidence time of a particle with a temporal resolution of 10 ns and a dynamic range of 160 {mu}s. Results of the first time application of the Medipix2 detector to VMImore » are presented, investigating the quantum efficiency as well as the possibility to operate at increased background pressure in the vacuum chamber.« less

Moduli vacuum bubbles produced by evaporating black holes

DOE Office of Scientific and Technical Information (OSTI.GOV)

Morris, J. R.

2007-10-15

We consider a model with a toroidally compactified extra dimension giving rise to a temperature-dependent 4D effective potential with one-loop contributions due to the Casimir effect, along with a 5D cosmological constant. The forms of the effective potential at low and high temperatures indicate a possibility for the formation of a domain wall bubble, formed by the modulus scalar field, surrounding an evaporating black hole. This is viewed as an example of a recently proposed black hole vacuum bubble arising from matter-sourced moduli fields in the vicinity of an evaporating black hole [D. Green, E. Silverstein, and D. Starr, Phys.more » Rev. D 74, 024004 (2006)]. The black hole bubble can be highly opaque to lower-energy particles and photons, and thereby entrap them within. For high-temperature black holes, there may also be a symmetry-breaking black hole bubble of false vacuum of the type previously conjectured by Moss [I. G. Moss, Phys. Rev. D 32, 1333 (1985)], tending to reflect low-energy particles from its wall. A double bubble composed of these two different types of bubble may form around the black hole, altering the hole's emission spectrum that reaches outside observers. Smaller mass black holes that have already evaporated away could have left vacuum bubbles behind that contribute to the dark matter.« less

Practical quantum random number generator based on measuring the shot noise of vacuum states

DOE Office of Scientific and Technical Information (OSTI.GOV)

Shen Yong; Zou Hongxin; Tian Liang

2010-06-15

The shot noise of vacuum states is a kind of quantum noise and is totally random. In this paper a nondeterministic random number generation scheme based on measuring the shot noise of vacuum states is presented and experimentally demonstrated. We use a homodyne detector to measure the shot noise of vacuum states. Considering that the frequency bandwidth of our detector is limited, we derive the optimal sampling rate so that sampling points have the least correlation with each other. We also choose a method to extract random numbers from sampling values, and prove that the influence of classical noise canmore » be avoided with this method so that the detector does not have to be shot-noise limited. The random numbers generated with this scheme have passed ent and diehard tests.« less

Vacuum Virtues

ERIC Educational Resources Information Center

Rathey, Allen

2007-01-01

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…

Hole-transport material variation in fully vacuum deposited perovskite solar cells

NASA Astrophysics Data System (ADS)

Polander, Lauren E.; Pahner, Paul; Schwarze, Martin; Saalfrank, Matthias; Koerner, Christian; Leo, Karl

2014-08-01

This work addresses the effect of energy level alignment between the hole-transporting material and the active layer in vacuum deposited, planar-heterojunction CH3NH3PbIx-3Clx perovskite solar cells. Through a series of hole-transport materials, with conductivity values set using controlled p-doping of the layer, we correlate their ionization potentials with the open-circuit voltage of the device. With ionization potentials beyond 5.3 eV, a substantial decrease in both current density and voltage is observed, which highlights the delicate energetic balance between driving force for hole-extraction and maximizing the photovoltage. In contrast, when an optimal ionization potential match is found, the open-circuit voltage can be maximized, leading to power conversion efficiencies of up to 10.9%. These values are obtained with hole-transport materials that differ from the commonly used Spiro-MeO-TAD and correspond to a 40% performance increase versus this reference.

Topics in Cosmic String Physics and Vacuum Stability of Field Theories

NASA Astrophysics Data System (ADS)

Dasgupta, Indranil

1998-01-01

In this thesis I examine aspects of the vacuum state of quantum field theories. Namely, I study topological defects in the vacuum which appear as localized regions of non-zero energy density if the model system is unable to relax to a homogeneous and isotropic ground state because of topological constraints. I also examine the stability of the so called false vacua in theories that have multiple vacuum states with different energy densities. I first consider topological defects in the form of strings and independently the decay of false vacua in models of particle physics where the presence of either defects or of false vacua leads to interesting phenomenology. Then I describe a situation in which the defects arising from topological properties of the vacuum in turn affect the stability of the vacuum itself. In the first part of this work (chapters 2 and 3), I explore the phenomenology of cosmic strings. I introduce new string-like topological defects that resemble pairs of strings bound together. I give an existence proof of these 'binary strings' and then develop their cosmological properties in detail. I then propose a simple extension of the Standard Model in which cosmic strings may form and then decay through baryon number violating interactions leading to baryogenesis. I show that the model has distinct and testable signatures. In the second part of this work (chapters 4 and 5), I examine the vacua of several proposed models of gauge mediated dynamical supersymmetry breaking and show that the viable vacua are often unstable. I develop a rigorous theory for approximating vacuum tunneling rates in multi-scalar field theories and by computing bounds on the decay rate of the vacua in these models obtain useful constraints on the parameter space. In the final part of this work (chapter 6), I develop a theory of vacuum tunneling induced by topological defects. I show that defects can speed up vacuum tunneling rates by seeding new kinds of bubbles during a first

Preterm birth by vacuum extraction and neonatal outcome: a population-based cohort study.

PubMed

Åberg, Katarina; Norman, Mikael; Ekéus, Cecilia

2014-01-22

Very few studies have investigated the neonatal outcomes after vacuum extraction delivery (VE) in the preterm period and the results of these studies are inconclusive. The objective of this study was to describe the use of VE for preterm delivery in Sweden and to compare rates of neonatal complications after preterm delivery by VE to those found after cesarean section during labor (CS) or unassisted vaginal delivery (VD). Data was obtained from Swedish national registers. In a population-based cohort from 1999 to 2010, all live-born, singleton preterm infants in a non-breech presentation at birth, born after onset of labor (either spontaneously, by induction, or by rupture of membranes) by VD, CS, or VE were included, leaving a study population of 40,764 infants. Logistic regression analyses were used to calculate adjusted odds ratios (AOR), using unassisted vaginal delivery as reference group. VE was used in 5.7% of the preterm deliveries, with lower rates in earlier gestations. Overall, intracranial hemorrhage (ICH) occurred in 1.51%, extracranial hemorrhage (ECH) in 0.64%, and brachial plexus injury in 0.13% of infants. Infants delivered by VE had higher risks for ICH (AOR = 1.84 (95% CI: 1.09-3.12)), ECH (AOR = 4.48 (95% CI: 2.84-7.07)) and brachial plexus injury (AOR = 6.21 (95% CI: 2.22-17.4)), while infants delivered by CS during labor had no increased risk for these complications, as compared to VD. While rates of neonatal complications after VE are generally low, higher odds ratios for intra- and extracranial hemorrhages and brachial plexus injuries after VE, compared with other modes of delivery, support a continued cautious use of VE for preterm delivery.

Ultra high vacuum broad band high power microwave window

DOEpatents

Nguyen-Tuong, V.; Dylla, H.F. III

1997-11-04

An improved high vacuum microwave window has been developed that utilizes high density polyethylene coated on two sides with SiOx, SiNx, or a combination of the two. The resultant low dielectric and low loss tangent window creates a low outgassing, low permeation seal through which broad band, high power microwave energy may be passed. No matching device is necessary and the sealing technique is simple. The features of the window are broad band transmission, ultra-high vacuum compatibility with a simple sealing technique, low voltage standing wave ratio, high power transmission and low cost. 5 figs.

Ultra high vacuum broad band high power microwave window

DOEpatents

Nguyen-Tuong, Viet; Dylla, III, Henry Frederick

1997-01-01

An improved high vacuum microwave window has been developed that utilizes high density polyethylene coated on two sides with SiOx, SiNx, or a combination of the two. The resultant low dielectric and low loss tangent window creates a low outgassing, low permeation seal through which broad band, high power microwave energy may be passed. No matching device is necessary and the sealing technique is simple. The features of the window are broad band transmission, ultra-high vacuum compatibility with a simple sealing technique, low voltage standing wave ratio, high power transmission and low cost.

Electromagnetic radiation energy arrangement. [coatings for solar energy absorption and infrared reflection

NASA Technical Reports Server (NTRS)

Lipkis, R. R.; Vehrencamp, J. E. (Inventor)

1965-01-01

A solar energy collector and infrared energy reflector is described which comprises a vacuum deposited layer of aluminum of approximately 200 to 400 Angstroms thick on one side of a substrate. An adherent layer of titanium with a thickness of between 800 and 1000 Angstroms is vacuum deposited on the aluminum substrate and is substantially opaque to solar energy and substantially transparent to infrared energy.

Energy production using fission fragment rockets

NASA Astrophysics Data System (ADS)

Chapline, G.; Matsuda, Y.

1991-08-01

Fission fragment rockets are nuclear reactors with a core consisting of thin fibers in a vacuum, and which use magnetic fields to extract the fission fragments from the reactor core. As an alternative to ordinary nuclear reactors, fission fragment rockets would have the following advantages: approximately twice the efficiency if the fission fragment energy can be directly converted into electricity; reduction of the buildup of a fission fragment inventory in the reactor could avoid a Chernobyl type disaster; and collection of the fission fragments outside the reactor could simplify the waste disposal problem.

An image-domain, contrast material extraction method for Dual-Energy CT

PubMed Central

Lambert, Jack W.; Sun, Yuxin; Gould, Robert G.; Ohliger, Michael A.; Li, Zhixi; Yeh, Benjamin M.

2016-01-01

Objectives Conventional material decomposition techniques for dual-energy CT (DECT) assume mass or volume conservation, where the CT number of each voxel is fully assigned to predefined materials. We present an image-domain contrast material extraction process (CMEP) method that preferentially extracts contrast-producing materials while leaving the remaining image intact. Materials and Methods Image processing freeware (Fiji) is used to perform consecutive arithmetic operations on a dual-energy ratio map to generate masks, which are then applied to the original images to generate material-specific images. First, a low-energy image is divided by a high-energy image to generate a ratio map. The ratio map is then split into material-specific masks. Ratio intervals known to correspond to particular materials (e.g. iodine, calcium) are assigned a multiplier of 1, while ratio values in between these intervals are assigned linear gradients from 0 to 1. The masks are then multiplied by an original CT image to produce material-specific images. The method was tested quantitatively at Dual-Source (DSCT) and Rapid kVp-Switching CT (RSCT) with phantoms using pure and mixed formulations of tungsten, calcium and iodine. Errors were evaluated by comparing the known material concentrations with those derived from the CMEP material-specific images. Further qualitative evaluation was performed in vivo at RSCT with a rabbit model using identical CMEP parameters to the phantom. Orally administered tungsten, vascularly administered iodine, and skeletal calcium were used as the three contrast materials. Results All five material combinations; tungsten, iodine and calcium, and mixtures of tungsten-calcium and iodine-calcium, showed distinct dual-energy ratios, largely independent of material concentration at both DSCT and RSCT. The CMEP was successful in both phantoms and in vivo. For pure contrast materials in the phantom, the maximum error between the known and CMEP-derived material

Microfabricated triggered vacuum switch

DOEpatents

Roesler, Alexander W [Tijeras, NM; Schare, Joshua M [Albuquerque, NM; Bunch, Kyle [Albuquerque, NM

2010-05-11

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

Influence of Gap Distance on Vacuum Arc Characteristics of Cup Type AMF Electrode in Vacuum Interrupters

NASA Astrophysics Data System (ADS)

Cheng, Shaoyong; Xiu, Shixin; Wang, Jimei; Shen, Zhengchao

2006-11-01

The greenhouse effect of SF6 is a great concern today. The development of high voltage vacuum circuit breakers becomes more important. The vacuum circuit breaker has minimum pollution to the environment. The vacuum interrupter is the key part of a vacuum circuit breaker. The interrupting characteristics in vacuum and arc-controlling technique are the main problems to be solved for a longer gap distance in developing high voltage vacuum interrupters. To understand the vacuum arc characteristics and provide effective technique to control vacuum arc in a long gap distance, the arc mode transition of a cup-type axial magnetic field electrode is observed by a high-speed charge coupled device (CCD) video camera under different gap distances while the arc voltage and arc current are recorded. The controlling ability of the axial magnetic field on vacuum arc obviously decreases when the gap distance is longer than 40 mm. The noise components and mean value of the arc voltage significantly increase. The effective method for controlling the vacuum arc characteristics is provided by long gap distances based on the test results. The test results can be used as a reference to develop high voltage and large capacity vacuum interrupters.

Commissioning of the vacuum system of the KATRIN Main Spectrometer

DOE Office of Scientific and Technical Information (OSTI.GOV)

Arenz, M.; Babutzka, M.; Bahr, M.

The KATRIN experiment will probe the neutrino mass by measuring the β-electron energy spectrum near the endpoint of tritium β-decay. We performed an integral energy analysis by an electro-static spectrometer (``Main Spectrometer''), an ultra-high vacuum vessel with a length of 23.2 m, a volume of 1240 m 3, and a complex inner electrode system with about 120 000 individual parts. The strong magnetic field that guides the β-electrons is provided by super-conducting solenoids at both ends of the spectrometer. Its influence on turbo-molecular pumps and vacuum gauges had to be considered. Furthermore, a system consisting of 6 turbo-molecular pumps andmore » 3 km of non-evaporable getter strips has been deployed and was tested during the commissioning of the spectrometer. In this paper the configuration, the commissioning with bake-out at 300 °C, and the performance of this system are presented in detail. The vacuum system has to maintain a pressure in the 10 -11 mbar range. We demonstrated that the performance of the system is already close to these stringent functional requirements for the KATRIN experiment, which will start at the end of 2016.« less

Commissioning of the vacuum system of the KATRIN Main Spectrometer

DOE PAGES

Arenz, M.; Babutzka, M.; Bahr, M.; ...

2016-04-07

The KATRIN experiment will probe the neutrino mass by measuring the β-electron energy spectrum near the endpoint of tritium β-decay. We performed an integral energy analysis by an electro-static spectrometer (``Main Spectrometer''), an ultra-high vacuum vessel with a length of 23.2 m, a volume of 1240 m 3, and a complex inner electrode system with about 120 000 individual parts. The strong magnetic field that guides the β-electrons is provided by super-conducting solenoids at both ends of the spectrometer. Its influence on turbo-molecular pumps and vacuum gauges had to be considered. Furthermore, a system consisting of 6 turbo-molecular pumps andmore » 3 km of non-evaporable getter strips has been deployed and was tested during the commissioning of the spectrometer. In this paper the configuration, the commissioning with bake-out at 300 °C, and the performance of this system are presented in detail. The vacuum system has to maintain a pressure in the 10 -11 mbar range. We demonstrated that the performance of the system is already close to these stringent functional requirements for the KATRIN experiment, which will start at the end of 2016.« less

The MEMS Knudsen Compressor as a Vacuum Pump for Space Exploration Applications

NASA Technical Reports Server (NTRS)

Vargo, S. E.; Muntz, E. P.; Tang, W. C.

2000-01-01

Several lander, probe and rover missions currently under study at the Jet Propulsion Laboratory (JPL) and especially in the Microdevices Laboratory (MDL) Center for Space Microelectronics Technology, focus on utilizing microelectromechanical systems (MEMS) based instruments for science data gathering. These small instruments and NASA's commitment to "faster, better, cheaper" type missions has brought about the need for novel approaches to satisfying mission requirements. Existing in-situ instrument systems clearly lack novel and integrated methods for satisfying their vacuum needs. One attractive candidate for a MEMS vacuum pump is the Knudsen Compressor, which operates based on thermal transpiration. Thermal transpiration describes gas flows induced by temperature differences maintained across orifices, porous membranes or capillary tubes under rarefied conditions. This device has two overwhelmingly attractive features as a MEMS vacuum pump - no moving parts and no fluids. An initial estimate of a Knudsen Compressor's pumping power requirements for a surface atmospheric sampling task on Mars is less than 80 mW, significantly below than alternative pumps. Due to the relatively low energy use for this task and the applicability of the Knudsen Compressor to other applications, the development of a Knudsen Compressor utilizing MEMS fabrication techniques has been initiated. This paper discusses the initial fabrication of a single-stage MEMS Knudsen Compressor vacuum pump, provides performance criteria such as pumping speed, size, energy use and ultimate pressure and details vacuum pump applications in several MDL related in-situ instruments.

Effect of initial phase on error in electron energy obtained using paraxial approximation for a focused laser pulse in vacuum

DOE Office of Scientific and Technical Information (OSTI.GOV)

Singh, Kunwar Pal, E-mail: k-psingh@yahoo.com; Department of Physics, Shri Venkateshwara University, Gajraula, Amroha, Uttar Pradesh 244236; Arya, Rashmi

2015-09-14

We have investigated the effect of initial phase on error in electron energy obtained using paraxial approximation to study electron acceleration by a focused laser pulse in vacuum using a three dimensional test-particle simulation code. The error is obtained by comparing the energy of the electron for paraxial approximation and seventh-order correction description of the fields of Gaussian laser. The paraxial approximation predicts wrong laser divergence and wrong electron escape time from the pulse which leads to prediction of higher energy. The error shows strong phase dependence for the electrons lying along the axis of the laser for linearly polarizedmore » laser pulse. The relative error may be significant for some specific values of initial phase even at moderate values of laser spot sizes. The error does not show initial phase dependence for a circularly laser pulse.« less

Laser-induced damage and fracture in fused silica vacuum windows

NASA Astrophysics Data System (ADS)

Campbell, John H.; Hurst, Patricia A.; Heggins, Dwight D.; Steele, William A.; Bumpas, Stanley E.

1997-05-01

Laser induced damage, that initiates catastrophic fracture, has been observed in large, fused silica lenses that also serve as vacuum barriers in high-fluence positions on the Nova and Beamlet lasers. In nearly all cases damage occurs on the vacuum side of the lens. The damage can lead to catastrophic crack growth if the flaw size exceeds the critical flaw size for SiO2. If the elastic stored energy in the lens in high enough, the lens will fracture into many pieces resulting in an implosion. The consequences of such an implosion can be severe, particularly for large vacuum systems. Three parameters control the degree of fracture in the vacuum barrier window: (1) the elastic stored energy, (2) the ratio of the window thickness to flaw depth and (3) secondary crack propagation. Fracture experiments have ben carried our on 15-cm diameter fused silica windows that contain surface flaws caused by laser damage. The results of these experiments, combined with data from window failures on Beamlet and Nova have been sued to develop design criteria for a 'fail-safe' lens. Specifically the window must be made thick enough such that the peak tensile stress is less than 500 psi and the corresponding ratio of the thickness to critical flaw size is less than 6. Under these conditions a properly mounted window, upon failure, will break into only tow pieces and will not implode. One caveat to these design criteria is that the air leak through the window before secondary crack growth occurs. Finite element stress calculations of a window before and immediately following fracture into two pieces show that the elastic stored energy is redistributed if the fragments 'lock' in place and thereby bridge the opening. In such cases, the peak stresses at the flaw site can increase leading to further crack growth.

Combined impacts of tidal energy extraction and sea level rise in the Gulf of Maine

NASA Astrophysics Data System (ADS)

Hashemi, M. R.; Kresning, B.

2016-12-01

The objective of this study was to assess the combined effects of SLR and tidal energy extraction on the dynamics of tides in the Gulf of Maine in both US and Canadian waters. The dynamics of tides in the Gulf of Maine is dominated by tidal resonance, which generates one of the largest tidal ranges in the world. Further, sea level rise (SLR) is affecting tidal circulations globally, and in the Gulf of Maine. A large tidal energy resource is available in the Gulf of Maine, particularly in the Bay of Fundy, and is expected to be harvested in the future. Currently, more than 6 projects are operational or under development in this region (in both US and Canadian waters). Understanding the far-field impacts of tidal-stream arrays is important for future development of tidal energy extraction. The impacts include possible changes in water elevation, which can potentially increase flooding in coastal areas. Further, SLR can affect tidal energy resources and the impacts of tidal energy extraction during the project lifetime - which is usually more than 25 years. A tidal model of the Gulf of Maine was developed using Regional Ocean Model System (ROMS) at one arcminute scale. An array of turbines were simulated in the model. After validation of the model at NOAA tidal gauge stations and NERACOOS buoys, several scenarios; including SLR scenario, and tidal extraction scenario, were examined. In particular, the results of a recent research was used to assess the impacts of SLR on the boundary of the model domain, which was neglected in previous studies. The results of the impacts of the tidal energy extraction with and without the SLR were presented, and compared with those from literature. This includes the decrease of tidal range and M2 amplitude in Minas Basin due to the 2.5 GW extraction scenario, and possible changes in Massachusetts coastal area. The impacts were compared with the level of uncertainty in the model. It was shown that the impact of SLR on the dynamics of

Vacuum boilers developed heating surfaces technic and economic efficiency evaluation

NASA Astrophysics Data System (ADS)

Slobodina, E. N.; Mikhailov, A. G.; Semenov, B. A.

2018-01-01

The vacuum boilers as manufacturing proto types application analysis was carried out, the possible directions for the heating surfaces development are identified with a view to improving the energy efficiency. Economic characteristics to evaluate the vacuum boilers application efficiency (Net Discounted Income (NDI), Internal Rate of Return (IRR), Profitability Index (PI) and Payback Period) are represented. The given type boilers application technic and economic efficiency criteria were established. NDI changing curves depending on the finning coefficient and operating pressure were obtained as a result of the conducted calculation studies.

Carbon Nanotube Vacuum Gauges Utilizing Long, Dissipative Tubes

NASA Technical Reports Server (NTRS)

Kaul, Anupama B.; Manohara, Harish M.

2008-01-01

CNT Vacuum Gauges: a) have a broad range of pressure response from 760 - 10(exp -6) Torr. b) have current changes approx. 100's nA in high vacuum regime (10(exp -6) Torr) and sensitivity increases with power and substrate removal. c) have a negative dR/dT (TCR negative) where a thermal hopping energy E(sub a) was determined to be approx. 40 meV. d) have compatible fabrication requirements for their integration with micromachined structures. e) can be operated at low power (nW - micro-W). f) have an active device region footprint of < 10 sq microns. g) are non-intrusive due to small size and passive operation.

An Optimal Control Method for Maximizing the Efficiency of Direct Drive Ocean Wave Energy Extraction System

PubMed Central

Chen, Zhongxian; Yu, Haitao; Wen, Cheng

2014-01-01

The goal of direct drive ocean wave energy extraction system is to convert ocean wave energy into electricity. The problem explored in this paper is the design and optimal control for the direct drive ocean wave energy extraction system. An optimal control method based on internal model proportion integration differentiation (IM-PID) is proposed in this paper though most of ocean wave energy extraction systems are optimized by the structure, weight, and material. With this control method, the heavy speed of outer heavy buoy of the energy extraction system is in resonance with incident wave, and the system efficiency is largely improved. Validity of the proposed optimal control method is verified in both regular and irregular ocean waves, and it is shown that IM-PID control method is optimal in that it maximizes the energy conversion efficiency. In addition, the anti-interference ability of IM-PID control method has been assessed, and the results show that the IM-PID control method has good robustness, high precision, and strong anti-interference ability. PMID:25152913

An optimal control method for maximizing the efficiency of direct drive ocean wave energy extraction system.

PubMed

Chen, Zhongxian; Yu, Haitao; Wen, Cheng

2014-01-01

The goal of direct drive ocean wave energy extraction system is to convert ocean wave energy into electricity. The problem explored in this paper is the design and optimal control for the direct drive ocean wave energy extraction system. An optimal control method based on internal model proportion integration differentiation (IM-PID) is proposed in this paper though most of ocean wave energy extraction systems are optimized by the structure, weight, and material. With this control method, the heavy speed of outer heavy buoy of the energy extraction system is in resonance with incident wave, and the system efficiency is largely improved. Validity of the proposed optimal control method is verified in both regular and irregular ocean waves, and it is shown that IM-PID control method is optimal in that it maximizes the energy conversion efficiency. In addition, the anti-interference ability of IM-PID control method has been assessed, and the results show that the IM-PID control method has good robustness, high precision, and strong anti-interference ability.

Flux tubes in the SU(3) vacuum: London penetration depth and coherence length

NASA Astrophysics Data System (ADS)

Cea, Paolo; Cosmai, Leonardo; Cuteri, Francesca; Papa, Alessandro

2014-05-01

Within the dual superconductor scenario for the QCD confining vacuum, the chromoelectric field generated by a static qq¯ pair can be fitted by a function derived, by dual analogy, from a simple variational model for the magnitude of the normalized order parameter of an isolated Abrikosov vortex. Previous results for the SU(3) vacuum are revisited, but here the transverse chromoelectric field is measured by means of the connected correlator of two Polyakov loops and, in order to reduce noise, the smearing procedure is used instead of cooling. The penetration and coherence lengths of the flux tube are then extracted from the fit and compared with previous results.

Harmonics suppression of vacuum chamber eddy current induced fields with application to the Superconducting Super Collider (SSC) Low Energy Booster (LEB) Magnets

DOE Office of Scientific and Technical Information (OSTI.GOV)

Schlueter, R.D.; Halbach, K.

1991-12-04

This memo presents the formulation of an expression for eddy currents induced in a thin-walled conductor due to a time-dependent electromagnet field excitation. Then follows an analytical development for prediction of vacuum chamber eddy current induced field harmonics in iron-core electromagnets. A passive technique for harmonics suppression is presented with specific application to the design of the Superconducting Super Collider (SSC) Low Energy B (LEB) Magnets.

Energy Extraction from a Hypothetical MHK Array in a Section of the Mississippi River

NASA Astrophysics Data System (ADS)

Barco, J.; James, S. C.; Roberts, J. D.; Jones, C. A.; Jepsen, R. A.

2010-12-01

The world is facing many challenges meeting the energy demands for the future. Growing populations and developing economies as well as increasing energy expenditures highlight the need for a spectrum of energy sources. Concerns about pollution and climate change have led to increased interest in all forms of renewable energy to stabilize or decrease consumption of fossil fuels. One promising renewable is marine and hydrokinetic (MHK) energy, which has the potential to make important contributions to energy portfolios of the future. However, a primary question remains: How much energy can be extracted from MHK devices in rivers and oceans without significant environmental effects? This study focuses on the potential energy extraction from different hypothetical MHK array configurations in a section of the Mississippi River located near to Scotlandville Bend, Louisiana. Bathymetry data, obtained from Free Flow Power Corporation (FFP) via the US Army Corps bathymetry survey library, were interpolated onto a DELFT3D curvilinear, orthogonal grid of the system using ArcGIS 9.3.1. Boundary conditions are constrained by the upstream and downstream river flow rates and gage heights obtained from USGS website. Acoustic Doppler Current Profiler (ADCP) measurements obtained from FFP are used for pre-array model validation. Energy extraction is simulated using momentum sinks recently coded into SNL-EFDC, which is an augmented version of US EPA’s Environmental Fluid Dynamics Code (EFDC). SNL-EFDC model includes a new module which considers energy removal by MHK devices and commensurate changes to the turbulent kinetic energy and turbulent kinetic energy dissipation rate. As expected, average velocities decrease downstream of each MHK device due to energy extraction and blunt-body form drag from the MHK support structures. Changes in the flow field can alter sediment transport dynamics around and downstream of an MHK array; various hypothetical scenarios are examined. This

Panax red ginseng extract regulates energy expenditures by modulating PKA dependent lipid mobilization in adipose tissue.

PubMed

Cho, Hae-Mi; Kang, Young-Ho; Yoo, Hanju; Yoon, Seung-Yong; Kang, Sang-Wook; Chang, Eun-Ju; Song, Youngsup

2014-05-16

Regulation of balance between lipid accumulation and energy consumption is a critical step for the maintenance of energy homeostasis. Here, we show that Panax red ginseng extract treatments increased energy expenditures and prevented mice from diet induced obesity. Panax red ginseng extracts strongly activated Hormone Specific Lipase (HSL) via Protein Kinase A (PKA). Since activation of HSL induces lipolysis in WAT and fatty acid oxidation in brown adipose tissue (BAT), these results suggest that Panax red ginseng extracts reduce HFD induced obesity by regulating lipid mobilization. Copyright © 2014 Elsevier Inc. All rights reserved.

Vacuum probe surface sampler

NASA Technical Reports Server (NTRS)

Zahlava, B. A. (Inventor)

1973-01-01

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

Vacuum polarization effects on flat branes due to a global monopole

DOE Office of Scientific and Technical Information (OSTI.GOV)

Bezerra de Mello, E.R.

2006-05-15

In this paper we analyze the vacuum polarization effects associated with a massless scalar field in the higher-dimensional spacetime. Specifically we calculate the renormalized vacuum expectation value of the square of the field, <{phi}{sup 2}(x)>{sub Ren}, induced by a global monopole in the 'braneworld' scenario. In this context the global monopole lives in a n=3-dimensional submanifold of the higher-dimensional (bulk) spacetime, and our universe is represented by a transverse flat (p-1)-dimensional brane. In order to develop this analysis we calculate the general Green function admitting that the scalar field propagates in the bulk. Also a general curvature coupling parameter betweenmore » the field and the geometry is assumed. We explicitly show that the vacuum polarization effects depend crucially on the values attributed to p. We also investigate the general structure of the renormalized vacuum expectation value of the energy-momentum tensor, {sub Ren}, for p=3.« less

Vacuum polarization of the electromagnetic field near a rotating black hole

DOE Office of Scientific and Technical Information (OSTI.GOV)

Frolov, V.P.; Zel'nikov, A.I.

1985-12-15

The electromagnetic field contribution to the vacuum polarization near a rotating black hole is considered. It is shown that the problem of calculating the renormalized average value of the stress-energy tensor /sup ren/ for the Hartle-Hawking vacuum state at the pole of the event horizon can be reduced to the problem of electro- and magnetostatics in the Kerr spacetime. An explicit expression for /sup ren/ at the pole of the event horizon is obtained and its properties are discussed. It is shown that in the case of a nonrotating black hole the Page-Brown approximation for the electromagnetic stress-energy tensor givesmore » a result which coincides at the event horizon with the exact value of /sup ren/. .AE« less

From Extraction to Renewal: A Global Campaign for Healthy Energy.

PubMed

Wang, Jennifer S; Euripidou, Rico; Armstrong, Fiona; Jensen, Génon K; Karliner, Josh; Guinto, Renzo R; Zhao, Ang; Narayanan, Divya; Orris, Peter

2016-02-01

A global movement is emerging in the health sector to engage in discourse and advocacy on the health impacts and health costs of energy choices--specifically the health harms of extractive, climate-disrupting energy sources such as coal and gas. Individuals and organizations in the health sector have begun to address climate and energy issues at multiple levels of engagement, including with others in the health sector, with pollution-affected communities, with policy makers, and with the media. We present recent examples of health sector advocacy and leadership on the health impacts of energy choices and opportunities for broadening and deepening the movement. © The Author(s) 2016.

Determination of ionization energies of CnN (n=4-12): Vacuum-ultraviolet (VUV) photoionization experiments and theoretical calculations

DOE Office of Scientific and Technical Information (OSTI.GOV)

Kostko, Oleg; Zhou, Jia; Sun, Bian Jian

2010-06-10

Results from single photon vacuum ultraviolet photoionization of astrophysically relevant CnN clusters, n = 4 - 12, in the photon energy range of 8.0 eV to 12.8 eV are presented. The experimental photoionization efficiency curves, combined with electronic structure calculations, provide improved ionization energies of the CnN species. A search through numerous nitrogen-terminated CnN isomers for n=4-9 indicates that the linear isomer has the lowest energy, and therefore should be the most abundant isomer in the molecular beam. Comparison with calculated results also shed light on the energetics of the linear CnN clusters, particularly in the trends of the even-carbonmore » and the odd-carbon series. These results can help guide the search of potential astronomical observations of these neutral molecules together with their cations in highly ionized regions or regions with a high UV/VUV photon flux (ranging from the visible to VUV with flux maxima in the Lyman- region) in the interstellar medium.« less

Determination of ionization energies of CnN (n=4-12): Vacuum-ultraviolet (VUV) photoionization experiments and theoretical calculations

DOE Office of Scientific and Technical Information (OSTI.GOV)

Kostko, Oleg; Zhou, Jia; Sun, Bian Jian

2010-03-02

Results from single photon vacuum ultraviolet photoionization of astrophysically relevant CnN clusters, n = 4 - 12, in the photon energy range of 8.0 eV to 12.8 eV are presented. The experimental photoionization efficiency curves, combined with electronic structure calculations, provide improved ionization energies of the CnN species. A search through numerous nitrogen-terminated CnN isomers for n=4-9 indicates that the linear isomer has the lowest energy, and therefore should be the most abundant isomer in the molecular beam. Comparison with calculated results also shed light on the energetics of the linear CnN clusters, particularly in the trends of the even-carbonmore » and the odd-carbon series. These results can help guide the search of potential astronomical observations of these neutral molecules together with their cations in highly ionized regions or regions with a high UV/VUV photon flux (ranging from the visible to VUV with flux maxima in the Lyman-a region) in the interstellar medium.« less

Life cycle environmental impacts of vacuum cleaners and the effects of European regulation.

PubMed

Gallego-Schmid, Alejandro; Mendoza, Joan Manuel F; Jeswani, Harish Kumar; Azapagic, Adisa

2016-07-15

Energy efficiency of vacuum cleaners has been declining over the past decades while at the same time their number in Europe has been increasing. The European Commission has recently adopted an eco-design regulation to improve the environmental performance of vacuum cleaners. In addition to the existing directive on waste electrical and electronic equipment (WEEE), the regulation could potentially have significant effects on the environmental performance of vacuum cleaners. However, the scale of the effects is currently unknown, beyond scant information on greenhouse gas emissions. Thus, this paper considers for the first time life cycle environmental impacts of vacuum cleaners and the effects of the implementation of these regulations at the European level. The effects of electricity decarbonisation, product lifetime and end-of-life disposal options are also considered. The results suggest that the implementation of the eco-design regulation alone will reduce significantly the impacts from vacuum cleaners (37%-44%) by 2020 compared with current situation. If business as usual continued and the regulation was not implemented, the impacts would be 82%-109% higher by 2020 compared to the impacts with the implementation of the regulation. Improvements associated with the implementation of the WEEE directive will be much smaller (<1% in 2020). However, if the WEEE directive did not exist, then the impacts would be 2%-21% higher by 2020 relative to the impacts with the implementation of the directive. Further improvements in most impacts (6%-20%) could be achieved by decarbonising the electricity mix. Therefore, energy efficiency measures must be accompanied by appropriate actions to reduce the environmental impacts of electricity generation; otherwise, the benefits of improved energy efficiency could be limited. Moreover, because of expected lower life expectancy of vacuum cleaners and limited availability of some raw materials, the eco-design regulation should be

Research of vacuum polymer film on three-dimension surface (Conference Presentation)

NASA Astrophysics Data System (ADS)

Bau, Yung-Han

2016-09-01

This study focused on UV-curable acrylic hybrid of solute in vacuum-deposited on the surface and make it smooth. On the surface coating of the entire process, including the pre-treatment of organic solutes, vacuum, nozzle pressure, airflow, frequency ratio, the surface of the rotation rate, nozzle angle, UV light irradiation time, waste solute recycling.Organic solutes through a flow meter and precise measured,by high pressure or vibration of a piezoelectric material, spray our organic solute in a certain degree of vacuum,leaving nozzle of tiny micro-mist volatiles in a vacuum to form secondary atomization,deposited our surface,Since no UV light irradiation, the surface is a liquid having fluidity, so the non-planar substrates can have good performance, finally it is irradiated by UV light of sufficient energy solidify to form a solid film.The advantage of this approach is that a smooth surface,Strong adhesion, low-cost equipment, low temperature, a wide range of high deposition rate can be combined with other deposition method,Under vacuum have not waste because excess paint can be recycled.Avoid solute direct contact with human, relative to the environment-friendly.

Adding high time resolution to charge-state-specific ion energy measurements for pulsed copper vacuum arc plasmas

NASA Astrophysics Data System (ADS)

Tanaka, Koichi; Han, Liang; Zhou, Xue; Anders, André

2015-08-01

Charge-state-resolved ion energy-time distributions of pulsed Cu arc plasma were obtained by using direct (time-dependent) acquisition of the ion detection signal from a commercial ion mass-per-charge and energy-per-charge analyzer. We find a shift of energies of Cu2+, Cu3+ and Cu4+ ions to lower values during the first few hundred microseconds after arc ignition, which is evidence for particle collisions in the plasma. The generation of Cu+ ions in the later part of the pulse, measured by the increase of Cu+ signal intensity and an associated slight reduction of the mean charge state, points to charge exchange reactions between ions and neutrals. At the very beginning of the pulse, when the plasma expands into vacuum and the plasma potential strongly fluctuates, ions with much higher energy (over 200 eV) are observed. Early in the pulse, the ion energies observed are approximately proportional to the ion charge state, and we conclude that the acceleration mechanism is primarily based on acceleration in an electric field. This field is directed away from the cathode, indicative of a potential hump. Measurements by a floating probe suggest that potential structures travel, and ions moving in the traveling field can gain high energies up to a few hundred electron-volts. Later in the pulse, the approximate proportionality is lost, which is related to increased smearing out of different energies due to collisions with neutrals, and/or to a change of the acceleration character from electrostatic to ‘gas-dynamic’, i.e. dominated by pressure gradient.

Characterization of the Heat Extraction Capability of a Compliant, Sliding, Thermal Interface for Use in a High Temperature, Vacuum Microgravity Furnace

NASA Technical Reports Server (NTRS)

Bellomy-Ezell, Jenny; Farmer, Jeff; Breeding, Shawn; Spivey, Reggie

1999-01-01

Much of the material science gained in microgravity research requires processing a sample in a high performance furnace. One such furnace currently being designed is the Quench Module Insert (QMI). The Principle Investigators, for whom the furnace is proposed, require high temperature gradients in their cylindrical samples to achieve the science objectives. One of the components critical to achieving high sample axial temperature gradients in the Quench Module Insert is a high performance cold zone to extract the heat from the sample. This cold zone employs a compliant, sliding thermal interface based on a Vel-Therm felt. This felt provides a conductive path between the Sample Cartridge Assembly (SCA) exterior surface and the interior surface of the water cooled chill block while allowing movement of the sample relative to the chill block. The Vel-Therm felt is composed of long polymer-based fibers affixed to a thin flexible substrate layer. The fibers are oriented perpendicular to this substrate giving the felt the appearance of a velvet fabric. The Vel-Therm felt heat extraction capability was quantified in earlier tests performed in an inert gas environment. The current activity, described in this paper, is intended to characterize the extraction capability of Vel-Therm felt in a vacuum environment similar to the QMI environment. This testing is necessary to quantify the thermal performance of the Vel-Therm felt and the sensitivity of that performance to key variables. The data derived from these tests will be incorporated into the current thermal models to improve the quality of the models and reduce uncertainty of the analytical results. In addition, the data will be used to help select the appropriate Vel-Therm felt and set proper operating limits as well as assess the performance range of the furnace. The objective of this test is to measure the heat extraction rate of the Vel-Therm felt as specified by the effective heat transfer coefficient. Therefore, the

Living beyond the edge: Higgs inflation and vacuum metastability

DOE PAGES

Bezrukov, Fedor; Rubio, Javier; Shaposhnikov, Mikhail

2015-10-13

The measurements of the Higgs mass and top Yukawa coupling indicate that we live in a very special universe, at the edge of the absolute stability of the electroweak vacuum. If fully stable, the Standard Model (SM) can be extended all the way up to the inflationary scale and the Higgs field, nonminimally coupled to gravity with strength ξ, can be responsible for inflation. We show that the successful Higgs inflation scenario can also take place if the SM vacuum is not absolutely stable. This conclusion is based on two effects that were overlooked previously. The first one is associatedmore » with the effective renormalization of the SM couplings at the energy scale M P/ξ, where M P is the Planck scale. Lastly, the second one is a symmetry restoration after inflation due to high temperature effects that leads to the (temporary) disappearance of the vacuum at Planck values of the Higgs field.« less

Energy extraction of a spinning particle via the super Penrose process from an extremal Kerr black hole

NASA Astrophysics Data System (ADS)

Liu, Yan; Liu, Wen-Biao

2018-03-01

The energy extraction of the collisional Penrose process has been investigated in recent years. Previous researchers mainly concentrated on the case of nonspin massive or massless particles, and they discovered that when the collision occurs near the horizon of extremal rotating black holes, the arbitrary large efficiency can be achieved with the particle's angular momentum below the critical value as L1<2 . In this paper, the energy extraction of spinning massive particles is calculated via the super Penrose process. We obtain the dependence of the impact factor and the turning points on the particle's spin s . The super Penrose process can occur only when s ≤1 and J1<2 , where J1 is the spinning particle's angular momentum. It is found that the efficiency of the energy extraction is monotonously increasing with the particle's spin s increasing for s <1 , and it can become arbitrarily high when the collision occurs close to the horizon. We compare the maximum extracted energy of spinning particles with that of the nonspin case and find a significant increase of the extracted energy. When s →1 , the maximum extracted energy can be orders of magnitude larger than that of the nonspin case. For the astrophysical black holes, the large efficiency is also obtained. Naturally, when the particle's spin s ≪1 , we can degenerate the result back to the nonspin case.

A radiation hard vacuum switch

DOEpatents

Boettcher, G.E.

1988-07-19

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

Comparison of vacuum rise time, vacuum limit accuracy, and occlusion break surge of 3 new phacoemulsification systems.

PubMed

Han, Young Keun; Miller, Kevin M

2009-08-01

To compare vacuum rise time, vacuum limit accuracy, and occlusion break surge of 3 new phacoemulsification machines. Jules Stein Eye Institute and Department of Ophthalmology, David Geffen School of Medicine at UCLA, Los Angeles, California, USA. The vacuum rise time under normal and enhanced aspiration modes, vacuum limit accuracy, and occlusion break surge of the Infiniti Vision System, Stellaris Vision Enhancement System, and WhiteStar Signature Phacoemulsification System were tested. Vacuum rise time and limit accuracy were measured at limit settings of 400 mm Hg and 600 mm Hg. Surge area was recorded at vacuum limit settings of 200 mm Hg, 300 mm Hg, 400 mm Hg, and 500 mm Hg. The Infiniti had the fastest vacuum rise times under normal and enhanced aspiration modes. At 4 seconds, the vacuum limit accuracy was greatest with the Infiniti at the 400 mm Hg limit and the Signature at the 600 mm Hg limit. The Stellaris did not reach either vacuum target. The Infiniti performed better than the other 2 machines during testing of occlusion break surge at all vacuum limit settings above 200 mm Hg. Under controlled laboratory test conditions, the Infiniti had the fastest vacuum rise time, greatest vacuum limit accuracy at 400 mm Hg, and least occlusion break surge. These results can be explained by the lower compliance of the Infiniti system.

Numerical research of the swirling supersonic gas flows in the self-vacuuming vortex tube

NASA Astrophysics Data System (ADS)

Volov, V. T.; Lyaskin, A. S.

2018-03-01

This article presents the results of simulation for a special type of vortex tubes – self-vacuuming vortex tube (SVVT), for which extreme values of temperature separation and vacuum are realized. The main results of this study are the flow structure in the SVVT and energy loss estimations on oblique shock waves, gas friction, instant expansion and organization of vortex bundles in SVVT.

Quantum vacuum interaction between two cosmic strings revisited

NASA Astrophysics Data System (ADS)

Muñoz-Castañeda, J. M.; Bordag, M.

2014-03-01

We reconsider the quantum vacuum interaction energy between two straight parallel cosmic strings. This problem was discussed several times in an approach treating both strings perturbatively and treating only one perturbatively. Here we point out that a simplifying assumption made by Bordag [Ann. Phys. (Berlin) 47, 93 (1990).] can be justified and show that, despite the global character of the background, the perturbative approach delivers a correct result. We consider the applicability of the scattering methods, developed in the past decade for the Casimir effect, for the cosmic string and find it not applicable. We calculate the scattering T-operator on one string. Finally, we consider the vacuum interaction of two strings when each carries a two-dimensional delta function potential.

Air bearing vacuum seal assembly

DOEpatents

Booth, Rex

1978-01-01

An air bearing vacuum seal assembly capable of rotating at the speed of several thousand revolutions per minute using an air cushion to prevent the rotating and stationary parts from touching, and a two stage differential pumping arrangement to maintain the pressure gradient between the air cushion and the vacuum so that the leak rate into the vacuum is, for example, less than 1 .times. 10.sup.-4 Pa m.sup.3 /s. The air bearing vacuum seal has particular application for mounting rotating targets to an evacuated accelerator beam tube for bombardment of the targets with high-power charged particle beams in vacuum.

Vacuum-Gauge Connection For Shipping Container

NASA Technical Reports Server (NTRS)

Henry, Robert H.

1990-01-01

External connector enables measurement of vacuum in stored part. Remote-readout connector added to shipping container and connected to thermo-couple vacuum gauge in vacuum-insulated cryogenic line packed in container. Enables monitoring of condition of vacuum without opening container.

Starobinsky-Like Inflation and Running Vacuum in the Context of Supergravity

NASA Astrophysics Data System (ADS)

Basilakos, Spyros; Mavromatos, Nick; Solà, Joan

2016-07-01

We describe the primeval inflationary phase of the early Universe within a quantum field theoretical (QFT) framework that can be viewed as the effective action of vacuum decay in the early times. Interestingly enough, the model accounts for the "graceful exit" of the inflationary phase into the standard radiation regime. The underlying QFT framework considered here is Supergravity (SUGRA), more specifically an existing formulation in which the Starobinsky-type inflation (de-Sitter background) emerges from the quantum corrections to the effective action after integrating out the gravitino fields in their (dynamically induced) massive phase. We also demonstrate that the structure of the effective action in this model is consistent with the generic idea of renormalization group (RG) running of the cosmological parameters, specifically it follows from the corresponding RG equation for the vacuum energy density as a function of the Hubble rate, $\\rho_{\\Lambda}(H)$. Overall our combined approach amounts to a concrete-model realization of inflation triggered by vacuum decay in a fundamental physics context which, as it turns out, can also be extended for the remaining epochs of the cosmological evolution until the current dark energy era.

NSLS II Vacuum System

DOE Office of Scientific and Technical Information (OSTI.GOV)

Ferreira, M.; Doom, L.; Hseuh, H.

2009-09-13

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 andmore » mounting the chambers are given.« less

Polarized x-ray emission from magnetized neutron stars: signature of strong-field vacuum polarization.

PubMed

Lai, Dong; Ho, Wynn C G

2003-08-15

In the atmospheric plasma of a strongly magnetized neutron star, vacuum polarization can induce a Mikheyev-Smirnov-Wolfenstein type resonance across which an x-ray photon may (depending on its energy) convert from one mode into the other, with significant changes in opacities and polarizations. We show that this vacuum resonance effect gives rise to a unique energy-dependent polarization signature in the surface emission from neutron stars. The detection of polarized x rays from neutron stars can provide a direct probe of strong-field quantum electrodynamics and constrain the neutron star magnetic field and geometry.

Polarized X-Ray Emission from Magnetized Neutron Stars: Signature of Strong-Field Vacuum Polarization

NASA Astrophysics Data System (ADS)

Lai, Dong; Ho, Wynn C.

2003-08-01

In the atmospheric plasma of a strongly magnetized neutron star, vacuum polarization can induce a Mikheyev-Smirnov-Wolfenstein type resonance across which an x-ray photon may (depending on its energy) convert from one mode into the other, with significant changes in opacities and polarizations. We show that this vacuum resonance effect gives rise to a unique energy-dependent polarization signature in the surface emission from neutron stars. The detection of polarized x rays from neutron stars can provide a direct probe of strong-field quantum electrodynamics and constrain the neutron star magnetic field and geometry.

Weighing neutrinos in the scenario of vacuum energy interacting with cold dark matter: application of the parameterized post-Friedmann approach

DOE Office of Scientific and Technical Information (OSTI.GOV)

Guo, Rui-Yun; Li, Yun-He; Zhang, Jing-Fei

We constrain the neutrino mass in the scenario of vacuum energy interacting with cold dark matter by using current cosmological observations. To avoid the large-scale instability problem in interacting dark energy models, we employ the parameterized post-Friedmann (PPF) approach to do the calculation of perturbation evolution, for the Q = β H ρ{sub c} and Q = β H ρ{sub Λ} models. The current observational data sets used in this work include Planck (cosmic microwave background), BSH (baryon acoustic oscillations, type Ia supernovae, and Hubble constant), and LSS (redshift space distortions and weak lensing). According to the constraint results, wemore » find that β > 0 at more than 1σ level for the Q = β H ρ{sub c} model, which indicates that cold dark matter decays into vacuum energy; while β = 0 is consistent with the current data at 1σ level for the Q = β H ρ{sub Λ} model. Taking the ΛCDM model as a baseline model, we find that a smaller upper limit, ∑ m {sub ν} < 0.11 eV (2σ), is induced by the latest BAO BOSS DR12 data and the Hubble constant measurement H {sub 0} = 73.00 ± 1.75 km s{sup −1} Mpc{sup −1}. For the Q = β H ρ{sub c} model, we obtain ∑ m {sub ν}<0.20 eV (2σ) from Planck+BSH. For the Q = β H ρ{sub Λ} model, ∑ m {sub ν}<0.10 eV (2σ) and ∑ m {sub ν}<0.14 eV (2σ) are derived from Planck+BSH and Planck+BSH+LSS, respectively. We show that these smaller upper limits on ∑ m {sub ν} are affected more or less by the tension between H {sub 0} and other observational data.« less

Effective Porosity Measurements by Wet- and Dry-type Vacuum Saturations using Process-Programmable Vacuum Saturation System

NASA Astrophysics Data System (ADS)

Lee, T. J.; Lee, K. S., , Dr; Lee, S. K.

2017-12-01

One of the most important factors in measuring effective porosity by vacuum saturation method is that the air in the pore space can be fully substituted by water during the vacuum saturation process. International Society of Rock Mechanics (ISRM) suggests vacuuming a rock sample submerged in the water, while American Society of Test and Materials (ASTM) vacuuming the sample and water separately and then pour the water to the sample. In this study, we call the former wet-type vacuum saturation (WVS) method and the latter dry-type vacuum saturation (DVS) method, and compare the effective porosity measured by the two different vacuum saturation processes. For that purpose, a vacuum saturation system has been developed, which can support both WVS and DVS by only changing the process by programming. Comparison of effective porosity has been made for a cement mortar and rock samples. As a result, DVS can substitute more void volume to water than WVS, which in turn insists that DVS can provide more exact value of effective porosity than WVS.

Time-frequency energy density precipitation method for time-of-flight extraction of narrowband Lamb wave detection signals

DOE Office of Scientific and Technical Information (OSTI.GOV)

Zhang, Y., E-mail: thuzhangyu@foxmail.com; Huang, S. L., E-mail: huangsling@tsinghua.edu.cn; Wang, S.

The time-of-flight of the Lamb wave provides an important basis for defect evaluation in metal plates and is the input signal for Lamb wave tomographic imaging. However, the time-of-flight can be difficult to acquire because of the Lamb wave dispersion characteristics. This work proposes a time-frequency energy density precipitation method to accurately extract the time-of-flight of narrowband Lamb wave detection signals in metal plates. In the proposed method, a discrete short-time Fourier transform is performed on the narrowband Lamb wave detection signals to obtain the corresponding discrete time-frequency energy density distribution. The energy density values at the center frequency formore » all discrete time points are then calculated by linear interpolation. Next, the time-domain energy density curve focused on that center frequency is precipitated by least squares fitting of the calculated energy density values. Finally, the peak times of the energy density curve obtained relative to the initial pulse signal are extracted as the time-of-flight for the narrowband Lamb wave detection signals. An experimental platform is established for time-of-flight extraction of narrowband Lamb wave detection signals, and sensitivity analysis of the proposed time-frequency energy density precipitation method is performed in terms of propagation distance, dispersion characteristics, center frequency, and plate thickness. For comparison, the widely used Hilbert–Huang transform method is also implemented for time-of-flight extraction. The results show that the time-frequency energy density precipitation method can accurately extract the time-of-flight with relative error of <1% and thus can act as a universal time-of-flight extraction method for narrowband Lamb wave detection signals.« less

Time-frequency energy density precipitation method for time-of-flight extraction of narrowband Lamb wave detection signals.

PubMed

Zhang, Y; Huang, S L; Wang, S; Zhao, W

2016-05-01

The time-of-flight of the Lamb wave provides an important basis for defect evaluation in metal plates and is the input signal for Lamb wave tomographic imaging. However, the time-of-flight can be difficult to acquire because of the Lamb wave dispersion characteristics. This work proposes a time-frequency energy density precipitation method to accurately extract the time-of-flight of narrowband Lamb wave detection signals in metal plates. In the proposed method, a discrete short-time Fourier transform is performed on the narrowband Lamb wave detection signals to obtain the corresponding discrete time-frequency energy density distribution. The energy density values at the center frequency for all discrete time points are then calculated by linear interpolation. Next, the time-domain energy density curve focused on that center frequency is precipitated by least squares fitting of the calculated energy density values. Finally, the peak times of the energy density curve obtained relative to the initial pulse signal are extracted as the time-of-flight for the narrowband Lamb wave detection signals. An experimental platform is established for time-of-flight extraction of narrowband Lamb wave detection signals, and sensitivity analysis of the proposed time-frequency energy density precipitation method is performed in terms of propagation distance, dispersion characteristics, center frequency, and plate thickness. For comparison, the widely used Hilbert-Huang transform method is also implemented for time-of-flight extraction. The results show that the time-frequency energy density precipitation method can accurately extract the time-of-flight with relative error of <1% and thus can act as a universal time-of-flight extraction method for narrowband Lamb wave detection signals.

Stability of stationary-axisymmetric black holes in vacuum general relativity to axisymmetric electromagnetic perturbations

NASA Astrophysics Data System (ADS)

Prabhu, Kartik; Wald, Robert M.

2018-01-01

We consider arbitrary stationary and axisymmetric black holes in general relativity in (d +1) dimensions (with d ≥slant 3 ) that satisfy the vacuum Einstein equation and have a non-degenerate horizon. We prove that the canonical energy of axisymmetric electromagnetic perturbations is positive definite. This establishes that all vacuum black holes are stable to axisymmetric electromagnetic perturbations. Our results also hold for asymptotically de Sitter black holes that satisfy the vacuum Einstein equation with a positive cosmological constant. Our results also apply to extremal black holes provided that the initial perturbation vanishes in a neighborhood of the horizon.

Vacuum Potentials for the Two Only Permanent Free Particles, Proton and Electron. Pair Productions

NASA Astrophysics Data System (ADS)

Zheng-Johansson, J. X.

2012-02-01

The two only species of isolatable, smallest, or unit charges +e and -e present in nature interact with the universal vacuum in a polarisable dielectric representation through two uniquely defined vacuum potential functions. All of the non-composite subatomic particles containing one-unit charges, +e or -e, are therefore formed in terms of the IED model of the respective charges, of zero rest masses, oscillating in either of the two unique vacuum potential fields, together with the radiation waves of their own charges. In this paper we give a first principles treatment of the dynamics of charge in a dielectric vacuum, based on which, combined with solutions for the radiation waves obtained previously, we subsequently derive the vacuum potential function for a given charge q, which we show to be quadratic and consist each of quantised potential levels, giving therefore rise to quantised characteristic oscillation frequencies of the charge and accordingly quantised, sharply-defined masses of the IED particles. By further combining with relevant experimental properties as input information, we determine the IED particles built from the charges +e, -e at their first excited states in the respective vacuum potential wells to be the proton and the electron, the observationally two only stable (permanently lived) and "free" particles containing one-unit charges. Their antiparticles as produced in pair productions can be accordingly determined. The characteristics of all of the other more energetic single-charged non-composite subatomic particles can also be recognised. We finally discuss the energy condition for pair production, which requires two successive energy supplies to (1) first disintegrate the bound pair of vaculeon charges +e, -e composing a vacuuon of the vacuum and (2) impart masses to the disintegrated charges.

Quantum vacuum polarization, nanotechnology and a robotic mission to Proxima Centauri

NASA Astrophysics Data System (ADS)

de Morais Mendonca Teles, Antonio

inertial mass of the mini-spacecraft has a relativistic increase factor of 0.005, fifty years of mission is a feasible one. A way of achieving this is by using altogether the possible available spacecraft acceleration: gravity assistance, ionic propulsion, and using characteristics of the medium through which any spacecrafts travel by -vacuum. Vacuum has intrinsic quantum properties such as quantum tunneling, latent quantum residual energy, and the quantum vac-uum polarization phenomenon. I also propose the use of such quantum vacuum polarization (QVP) for the propulsion assistance for possible future Solar System and interstellar missions. QVP is a natural phenomenon arisen as a second-order correction for perturbation of quantum vacuum fluctuations, within the quantum field physics arena. It is related experimentally to the Casimir effect (the appearance of a negative potential barrier between very close and par-allel metallic plates in vacuum). Using a laser beam with a minimum of 1.22 MeV energy it is possible to create inside those plates in vacuum 1 real pair of electron-positron (anti-electron), and associated with this there is the creation of 1 virtual pair of electron-positron, through the geometrodynamical arrangement of the quantum vacuum fluctuations states, with a very small interval of time (δt). With much greater energies (GeV, TeV) it is possible to create virtual pairs with much longer δt, with the appearance of a repulsive force between the real and asso-ciated virtual pairs, caused by forced alignment of the spins of the real and virtual pairs. This could be attained by the use of a magnetic field. A powerful laser put in the extremity of the mini-spacecraft (together with the ionic mini-motor) in the middle of Casimir plates, could use that repulsive force to get much more momentum to the mini-spacecraft, for a possible speed in the order of 0.1 c. Telecommunication aspect can be arranged through the use of a tracking and data relay mini

A Programmable Cellular-Automata Polarized Dirac Vacuum

NASA Astrophysics Data System (ADS)

Osoroma, Drahcir S.

2013-09-01

We explore properties of a `Least Cosmological Unit' (LCU) as an inherent spacetime raster tiling or tessellating the unique backcloth of Holographic Anthropic Multiverse (HAM) cosmology as an array of programmable cellular automata. The HAM vacuum is a scale-invariant HD extension of a covariant polarized Dirac vacuum with `bumps' and `holes' typically described by extended electromagnetic theory corresponding to an Einstein energy-dependent spacetime metric admitting a periodic photon mass. The new cosmology incorporates a unique form of M-Theoretic Calabi-Yau-Poincaré Dodecadedral-AdS5-DS5space (PDS) with mirror symmetry best described by an HD extension of Cramer's Transactional Interpretation when integrated also with an HD extension of the de Broglie-Bohm-Vigier causal interpretation of quantum theory. We incorporate a unique form of large-scale additional dimensionality (LSXD) bearing some similarity to that conceived by Randall and Sundrum; and extend the fundamental basis of our model to the Unified Field, UF. A Sagnac Effect rf-pulsed incursive resonance hierarchy is utilized to manipulate and ballistically program the geometric-topological properties of this putative LSXD space-spacetime network. The model is empirically testable; and it is proposed that a variety of new technologies will arise from ballistic programming of tessellated LCU vacuum cellular automata.

Experimental investigation on the energy deposition and morphology of the electrical explosion of copper wire in vacuum

DOE Office of Scientific and Technical Information (OSTI.GOV)

Shi, Zongqian; Shi, Yuanjie; Wang, Kun

2016-03-15

This paper presents the experimental results of the electrical explosion of copper wires in vacuum using negative nanosecond-pulsed current with magnitude of 1–2 kA. The 20 μm-diameter copper wires with different lengths are exploded with three different current rates. A laser probe is applied to construct the shadowgraphy and interferometry diagnostics to investigate the distribution and morphology of the exploding product. The interference phase shift is reconstructed from the interferogram, by which the atomic density distribution is calculated. Experimental results show that there exist two voltage breakdown modes depending on the amount of the specific energy deposition. For the strong-shunting mode, shuntingmore » breakdown occurs, leading to the short-circuit-like current waveform. For the weak-shunting mode with less specific energy deposition, the plasma generated during the voltage breakdown is not enough to form a conductive plasma channel, resulting in overdamped declining current waveform. The influence of the wire length and current rate on the characteristics of the exploding wires is also analyzed.« less

Ion energy distribution near a plasma meniscus with beam extraction for multi element focused ion beams

DOE Office of Scientific and Technical Information (OSTI.GOV)

Mathew, Jose V.; Paul, Samit; Bhattacharjee, Sudeep

2010-05-15

An earlier study of the axial ion energy distribution in the extraction region (plasma meniscus) of a compact microwave plasma ion source showed that the axial ion energy spread near the meniscus is small ({approx}5 eV) and comparable to that of a liquid metal ion source, making it a promising candidate for focused ion beam (FIB) applications [J. V. Mathew and S. Bhattacharjee, J. Appl. Phys. 105, 96101 (2009)]. In the present work we have investigated the radial ion energy distribution (IED) under the influence of beam extraction. Initially a single Einzel lens system has been used for beam extractionmore » with potentials up to -6 kV for obtaining parallel beams. In situ measurements of IED with extraction voltages upto -5 kV indicates that beam extraction has a weak influence on the energy spread ({+-}0.5 eV) which is of significance from the point of view of FIB applications. It is found that by reducing the geometrical acceptance angle at the ion energy analyzer probe, close to unidirectional distribution can be obtained with a spread that is smaller by at least 1 eV.« less

Statistical distribution of the vacuum energy density in racetrack Kähler uplift models in string theory

NASA Astrophysics Data System (ADS)

Sumitomo, Yoske; Tye, S.-H. Henry; Wong, Sam S. C.

2013-07-01

We study a racetrack model in the presence of the leading α'-correction in flux compactification in Type IIB string theory, for the purpose of getting conceivable de-Sitter vacua in the large compactified volume approximation. Unlike the Kähler Uplift model studied previously, the α'-correction is more controllable for the meta-stable de-Sitter vacua in the racetrack case since the constraint on the compactified volume size is very much relaxed. We find that the vacuum energy density Λ for de-Sitter vacua approaches zero exponentially as the volume grows. We also analyze properties of the probability distribution of Λ in this class of models. As in other cases studied earlier, the probability distribution again peaks sharply at Λ = 0. We also study the Racetrack Kähler Uplift model in the Swiss-Cheese type model.

Multipurpose Vacuum Induction Processing System

NASA Astrophysics Data System (ADS)

Govindaraju, M.; Kulkarni, Deepak; Balasubramanian, K.

2012-11-01

Multipurpose vacuum processing systems are cost effective; occupy less space, multiple functional under one roof and user friendly. A multipurpose vacuum induction system was designed, fabricated and installed in a record time of 6 months time at NFTDC Hyderabad. It was designed to function as a) vacuum induction melting/refining of oxygen free electronic copper/pure metals, b) vacuum induction melting furnace for ferrous materials c) vacuum induction melting for non ferrous materials d) large vacuum heat treatment chamber by resistance heating (by detachable coil and hot zone) e) bottom discharge vacuum induction melting system for non ferrous materials f) Induction heat treatment system and g) directional solidification /investment casting. It contains provision for future capacity addition. The attachments require to manufacture multiple shaped castings and continuous rod casting can be added whenever need arises. Present capacity is decided on the requirement for 10years of development path; presently it has 1.2 ton liquid copper handling capacity. It is equipped with provision for capacity addition up to 2 ton liquid copper handling capacity in future. Provision is made to carry out the capacity addition in easy steps quickly. For easy operational maintenance and troubleshooting, design was made in easily detachable sections. High vacuum system is also is detachable, independent and easily movable which is first of its kind in the country. Detailed design parameters, advantages and development history are presented in this paper.

The comparison of extraction of energy in two-cascade and one-cascade targets

DOE Office of Scientific and Technical Information (OSTI.GOV)

Dolgoleva, G. V., E-mail: dolgg@list.ru; Ponomarev, I. V., E-mail: wingof17@mail.ru

2016-01-15

The paper is devoted to numerical designing of cylindrical microtargets on the basis of shock-free compression. When designing microtargets for the controlled thermonuclear fusion, the core tasks are to select geometry and make-up of layers, and the law of energy embedding as well, which allow receiving of “burning” of deuterium- tritium mix, that is, the existence of thermonuclear reactions of working area. Yet, the energy yield as a result of thermonuclear reactions has to be more than the embedded energy (the coefficient of amplification is more than a unit). So, an important issue is the value of the embedded energy.more » The purpose of the present paper is to study the extraction of energy by working DT area in one-cascade and two-cascade targets. A bigger extraction of energy will contribute to a better burning of DT mix and a bigger energy yield as a result of thermonuclear reactions. The comparison of analytical results to numerical calculations is carried out. The received results show advantages of a two-cascade target compared to a one-cascade one.« less

Vacuum leak detector and method

DOEpatents

Edwards, Jr., David

1983-01-01

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.

Robot design for a vacuum environment

NASA Technical Reports Server (NTRS)

Belinski, S.; Trento, W.; Imani-Shikhabadi, R.; Hackwood, S.

1987-01-01

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.

Glow discharge cleaning of vacuum switch tubes

DOE Office of Scientific and Technical Information (OSTI.GOV)

Hayashi, T.; Toya, H.

1991-10-01

This paper reports that glow discharge cleaning has ben advancing as a means of degassing vacuum chambers constructed for a large accelerator or for nuclear fusion research. To clean the whole surface of parts inside a vacuum switch tube (VST), a new technique is tried which generates glow discharge between the inner electrodes and copper grid surrounding it. Photographic observation reveals that the glow discharge spreads out and cleans the whole surface inside the VST. A breakdown test between the inner electrodes shows the effect of the cleaning with this technique. Higher breakdown voltage between the inner electrodes is attainedmore » by performing this glow discharge cleaning in argon rather than hydrogen gas. The difference of the cleaning effect seems to be attributed to that of the energy transfer from ion species to the absorbed molecules and microprotrusions on the surfaces.« less

Weak stability of the plasma-vacuum interface problem

NASA Astrophysics Data System (ADS)

Catania, Davide; D'Abbicco, Marcello; Secchi, Paolo

2016-09-01

We consider the free boundary problem for the two-dimensional plasma-vacuum interface in ideal compressible magnetohydrodynamics (MHD). In the plasma region, the flow is governed by the usual compressible MHD equations, while in the vacuum region we consider the Maxwell system for the electric and the magnetic fields. At the free interface, driven by the plasma velocity, the total pressure is continuous and the magnetic field on both sides is tangent to the boundary. We study the linear stability of rectilinear plasma-vacuum interfaces by computing the Kreiss-Lopatinskiĭ determinant of an associated linearized boundary value problem. Apart from possible resonances, we obtain that the piecewise constant plasma-vacuum interfaces are always weakly linearly stable, independently of the size of tangential velocity, magnetic and electric fields on both sides of the characteristic discontinuity. We also prove that solutions to the linearized problem obey an energy estimate with a loss of regularity with respect to the source terms, both in the interior domain and on the boundary, due to the failure of the uniform Kreiss-Lopatinskiĭ condition, as the Kreiss-Lopatinskiĭ determinant associated with this linearized boundary value problem has roots on the boundary of the frequency space. In the proof of the a priori estimates, a crucial part is played by the construction of symmetrizers for a reduced differential system, which has poles at which the Kreiss-Lopatinskiĭ condition may fail simultaneously.

Fermionic vacuum polarization in a higher-dimensional global monopole spacetime

DOE Office of Scientific and Technical Information (OSTI.GOV)

Bezerra de Mello, E. R.

2007-12-15

In this paper we analyze the vacuum polarization effects associated with a massless fermionic field in a higher-dimensional global monopole spacetime in the 'braneworld' scenario. In this context we admit that our Universe, the bulk, is represented by a flat (n-1)-dimensional brane having a global monopole in an extra transverse three-dimensional submanifold. We explicitly calculate the renormalized vacuum average of the energy-momentum tensor, {sub Ren}, admitting the global monopole as being a pointlike object. We observe that this quantity depends crucially on the value of n, and provide explicit expressions to it for specific values attributed to n.

Mellin-Barnes approach to hadronic vacuum polarization and gμ-2

NASA Astrophysics Data System (ADS)

Charles, Jérôme; de Rafael, Eduardo; Greynat, David

2018-04-01

It is shown that with a precise determination of a few derivatives of the hadronic vacuum polarization (HVP) self-energy function Π (Q2) at Q2=0 , from lattice QCD (LQCD) or from a dedicated low-energy experiment, one can obtain an evaluation of the lowest order HVP contribution to the anomalous magnetic moment of the muon aμHVP with an accuracy comparable to the one reached using the e+e- annihilation cross section into hadrons. The technique of Mellin-Barnes approximants (MBa) that we propose is illustrated in detail with the example of the two loop vacuum polarization function in QED. We then apply it to the first few moments of the hadronic spectral function obtained from experiment and show that the resulting MBa evaluations of aμHVP converge very quickly to the full experimental determination.

Metabolomics Analysis of Cistus monspeliensis Leaf Extract on Energy Metabolism Activation in Human Intestinal Cells

PubMed Central

Shimoda, Yoichi; Han, Junkyu; Kawada, Kiyokazu; Smaoui, Abderrazak; Isoda, Hiroko

2012-01-01

Energy metabolism is a very important process to improve and maintain health from the point of view of physiology. It is well known that the intracellular ATP production is contributed to energy metabolism in cells. Cistus monspeliensis is widely used as tea, spices, and medical herb; however, it has not been focusing on the activation of energy metabolism. In this study, C. monspeliensis was investigated as the food resources by activation of energy metabolism in human intestinal epithelial cells. C. monspeliensis extract showed high antioxidant ability. In addition, the promotion of metabolites of glycolysis and TCA cycle was induced by C. monspeliensis treatment. These results suggest that C. monspeliensis extract has an ability to enhance the energy metabolism in human intestinal cells. PMID:22523469

Design and Fabrication of a Stirling Thermal Vacuum Test

NASA Technical Reports Server (NTRS)

Oriti, Salvatore M.; Schreiber, Jeffrey G.

2004-01-01

A Stirling Radioisotope Generator (SRG110) is being developed for potential use on future NASA space science missions. The development effort is being conducted by Lockheed Martin under contract to the Department of Energy (DOE). The Stirling Technology Company supplies the free-piston Stirling power convertors, and NASA Glenn Research Center (GRC) provides support to the effort in a range of technologies. This generator features higher efficiency and specific power compared to the currently used alternatives. One potential application for the generator would entail significant cruise time in the vacuum of deep space. A test has been conceived at GRC to demonstrate functionality of the Stirling convertors in a thermal vacuum environment. The test article resembles the configuration of the SRG, however the requirement for low mass was not considered. This test will demonstrate the operation of the Stirling convertors in the thermal vacuum environment, simulating deep space, over an extended period of operation. The analysis, design, and fabrication of the test article will be described in this paper.

Extended Operation of Stirling Convertors in a Thermal Vacuum Environment

NASA Technical Reports Server (NTRS)

Oriti, Salvatore M.

2006-01-01

A 110 watt Stirling Radioisotope Generator (SRG110) is being developed for potential use on future NASA exploration missions. The development effort is being performed by Lockheed Martin under contract to the Department of Energy (DOE). Infinia, Corp. supplies the free-piston Stirling power convertors, and NASA Glenn Research Center (GRC) provides support to the effort in a range of technologies. This generator features higher efficiency and specific power compared to alternatives. One potential application for the generator would entail significant cruise time in the vacuum of deep space. A test has been initiated at GRC to demonstrate functionality of the Stirling convertors in a thermal vacuum environment. The test article resembles the configuration of the SRG110, however the requirement for low mass was not considered. This test demonstrates the operation of the Stirling convertors in the thermal vacuum environment, simulating deep space, over an extended period of operation. The status of the test as well as the data gathered will be presented in this paper.

Design and investigation of a multichannel laser-triggered vacuum switch

DOE Office of Scientific and Technical Information (OSTI.GOV)

Fan, Wenfang, E-mail: fwf1990@126.com; He, Zhenghao; Mao, Xiaopo

2016-03-15

A laser-triggered vacuum switch (LTVS) is an advanced closing switch with nanosecond delay and jitter. In order to enhance hold-off voltage and extend the service lifetime of an LTVS, we designed a multichannel laser-triggered vacuum switch (MLTVS) utilizing a cone-shaped target electrode placed on the cathode platform. The fabrication and testing of the MLTVS is described in this paper. Experimental results show that the working voltage of the MLTVS with a gap distance of 12 mm is from 30 V to 20 kV. The threshold energy for triggering the switch is 0.4 mJ corresponding to a peak power density ofmore » 27.9 MW/cm{sup 2}. The triggering lifetime of a spot can reach up to 18 000 shots. In addition, the relationship between triggering lifetime and target materials is analyzed using a field emission scanning electron microscope. A hypothesis of the vacuum gap’s triggering mechanism is discussed based on the measured results.« less

Technical specification for vacuum systems

DOE Office of Scientific and Technical Information (OSTI.GOV)

Khaw, J.

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 andmore » 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)« less

Electrokinetic electrode system for extraction of soil contaminants from unsaturated soils

DOEpatents

Lindgren, Eric R.; Mattson, Earl D.

1995-01-01

There is presented an electrokinetic electrode assembly for use in extraction of soil contaminants from unsaturated soil in situ. The assembly includes a housing for retaining a liquid comprising an electrolyte solution, pure water, and soil water, the housing being in part of porous material capable of holding a vacuum. An electrode is mounted in the housing. The housing is provided with a vacuum orifice for effecting a vacuum within the housing selectively to control flow of soil water through the housing into the chamber and to control outflow of the liquid from the chamber. The assembly further includes conduit means for removing the liquid from the housing and returning the electrolyte solution to the housing, and a conduit for admitting pure water to the housing. There is further presented an electrode system and method for extraction of soil contaminants, the system and method utilizing at least two electrode assemblies as described above.

Electrokinetic electrode system for extraction of soil contaminants from unsaturated soils

DOEpatents

Lindgren, E.R.; Mattson, E.D.

1995-07-25

An electrokinetic electrode assembly is described for use in extraction of soil contaminants from unsaturated soil in situ. The assembly includes a housing for retaining a liquid comprising an electrolyte solution, pure water, and soil water, the housing being in part of porous material capable of holding a vacuum. An electrode is mounted in the housing. The housing is provided with a vacuum orifice for effecting a vacuum within the housing selectively to control flow of soil water through the housing into the chamber and to control outflow of the liquid from the chamber. The assembly further includes conduit means for removing the liquid from the housing and returning the electrolyte solution to the housing, and a conduit for admitting pure water to the housing. An electrode system and method are also revealed for extraction of soil contaminants. The system and method utilize at least two electrode assemblies as described above. 5 figs.

Acceleration of electron bunches by intense laser pulse in vacuum

NASA Astrophysics Data System (ADS)

Hua, J. F.; Ho, Y. K.; Lin, Y. Z.; Cao, N.

2003-08-01

This paper addresses the output characteristics of real electron bunches accelerated with ultra-intense laser pulse in vacuum by the capture & acceleration scenario (CAS) scheme (see, e.g., Phys. Rev. E66 (2002) 066501). Normally, the size of an electron bunch is much larger than that of a tightly focused and compressed laser pulse. We examine in detail the features of the intersection region, the distribution of electrons which can experience an intense laser field and be accelerated to high energy. Furthermore, the output properties of the accelerated CAS electrons, such as the energy spectra, the angular distributions, the energy-angle correlations, the acceleration gradient, the energy which can be reached with this scheme, the emittances of the outgoing electron bunches, and the dependence of the output properties on the incident electron beam qualities such as the emittance, focusing status, etc. were studied and explained. We found that with intense laser systems and electron beam technology currently available nowadays, the number of CAS electrons can reach 10 4-10 5, when the total number of incident electrons in the practical bunch reaches ˜10 8. These results demonstrate that CAS is promising to become a novel mechanism of vacuum laser accelerators.

Production of primordial gravitational waves in a simple class of running vacuum cosmologies

NASA Astrophysics Data System (ADS)

Tamayo, D. A.; Lima, J. A. S.; Bessada, D. F. A.

The problem of cosmological production of gravitational waves (GWs) is discussed in the framework of an expanding, spatially homogeneous and isotropic FRW type universe with time-evolving vacuum energy density. The GW equation is established and its modified time-dependent part is analytically resolved for different epochs in the case of a flat geometry. Unlike the standard ΛCDM cosmology (no interacting vacuum), we show that GWs are produced in the radiation era even in the context of general relativity. We also show that for all values of the free parameter, the high frequency modes are damped out even faster than in the standard cosmology both in the radiation and matter-vacuum dominated epoch. The formation of the stochastic background of gravitons and the remnant power spectrum generated at different cosmological eras are also explicitly evaluated. It is argued that measurements of the CMB polarization (B-modes) and its comparison with the rigid ΛCDM model plus the inflationary paradigm may become a crucial test for dynamical dark energy models in the near future.

Bakeout Chamber Within Vacuum Chamber

NASA Technical Reports Server (NTRS)

Taylor, Daniel M.; Soules, David M.; Barengoltz, Jack B.

1995-01-01

Vacuum-bakeout apparatus for decontaminating and measuring outgassing from pieces of equipment constructed by mounting bakeout chamber within conventional vacuum chamber. Upgrade cost effective: fabrication and installation of bakeout chamber simple, installation performed quickly and without major changes in older vacuum chamber, and provides quantitative data on outgassing from pieces of equipment placed in bakeout chamber.

Ejector/liquid ring pump provides <0. 30 mm Hg vacuum for polymerization vessel

DOE Office of Scientific and Technical Information (OSTI.GOV)

Lockwood, A.; Gaines, A.

1982-03-01

Firestone Fibers and Textiles Company, a division of Firestone Tire and Rubber Company, manufactures tire and industrial yarns of polyester and nylon-6. Nylon-6 molding and extrusion resins are also produced at the plant in Hopewell, Virginia. The process for making polyester requires an extremely low vacuum on the polymerization reactor. A consistent polymerization vessel vacuum of 0.3 mm Hg is needed, but the existing vacuum source, a five-stage steam jet ejector, could only provide a 0.5 mm Hg level. Two options were considered when the company decided to replace the original system with a system designed for 0.15 mm Hgmore » with a non-condensible gas load of 10.8 lb/hr. A new five-stage jet ejector system to meet these requirements would use 1395 lb/hr of 100 psig steam. The other option was a hybrid vacuum source composed of a three-stage steam ejector system and a liquid ring vacuum pump that is more energy efficient than ejectors for low vacuum applications. The hybrid system was selected because the three-stage jet ejector would use only 1240 lb/hr of 100 psig steam. The liquid ring vacuum pump would increase the material and installation cost of the system by about $4000, but the savings in steam consumption would pay back the added cost in less than two years. The jet ejector/liquid ring vacuum pump system has provided both the capacity and the extremely low vacuum needed for the polyester polymerization vessel, after making a small modification. The hybrid vacuum source is reliable, requires only routine maintenance, and will contiue to save substantial amounts of steam each year compared to the five-stage steam jet ejector.« less

Vacuum Surface Flashover Characteristics and Secondary Electron Emission Characteristics of Epoxy Resin and FRP Insulator

NASA Astrophysics Data System (ADS)

Yamano, Yasushi; Takahashi, Masahiro; Kobayashi, Shinichi; Hanada, Masaya; Ikeda, Yoshitaka

Neutral beam injectors (NBI) used for JT-60 are required to generate negative ions of 500 keV energies. To produce such high-energy ions, the electrostatic accelerators consisting of 3-stage of electrodes and three insulator rings are applied. The insulators are made of Fiberglass Reinforced Plastic (FRP) which is composed of epoxy resin and glass fibers. The surface discharges along the insulators are one of the most serious problems in the development of NBI. To increase the hold-off voltage against surface flashover events, it is necessary to investigate the FRP and epoxy resin insulator properties related to surface discharges in vacuum. This paper describes surface flashover characteristics for epoxy resin, FRP and Alumina samples under vacuum condition. In addition, the measurements of secondary electron emission (SEE) characteristics are also reported. These are important parameters to analyze surface discharge characteristics of insulators in vacuum.

Surface currents on the plasma-vacuum interface in MHD equilibria

NASA Astrophysics Data System (ADS)

Hanson, James D.

2016-10-01

The VMEC non-axisymmetric MHD equilibrium code can compute free-boundary equilibria. Since VMEC assumes that magnetic fields within the plasma form closed and nested flux surfaces, the plasma-vacuum interface is a flux surface, and the total magnetic field there has no normal component. VMEC imposes this condition of zero normal field using the potential formulation of Merkel, and solves a Neumann problem for the magnetic potential in the exterior region. This boundary condition necessarily admits the possibility of a surface current on the plasma-vacuum interface. While this current may be small in MHD equilibrium, this current may be readily computed in terms of a magnetic potential in both the interior and exterior regions. Examples of the surface current for VMEC equilibria will be shown. This material is based upon work supported by Auburn University and the U.S. Department of Energy, Office of Science, Office of Fusion Energy Sciences under Award Number DE-FG02-03ER54692.

Extracting the σ-term from low-energy pion-nucleon scattering

NASA Astrophysics Data System (ADS)

Ruiz de Elvira, Jacobo; Hoferichter, Martin; Kubis, Bastian; Meißner, Ulf-G.

2018-02-01

We present an extraction of the pion-nucleon (π N) scattering lengths from low-energy π N scattering, by fitting a representation based on Roy-Steiner equations to the low-energy data base. We show that the resulting values confirm the scattering-length determination from pionic atoms, and discuss the stability of the fit results regarding electromagnetic corrections and experimental normalization uncertainties in detail. Our results provide further evidence for a large π N σ-term, {σ }π N=58(5) {{MeV}}, in agreement with, albeit less precise than, the determination from pionic atoms.

Spacetime dynamics of a Higgs vacuum instability during inflation

DOE PAGES

East, William E.; Kearney, John; Shakya, Bibhushan; ...

2017-01-31

A remarkable prediction of the Standard Model is that, in the absence of corrections lifting the energy density, the Higgs potential becomes negative at large field values. If the Higgs field samples this part of the potential during inflation, the negative energy density may locally destabilize the spacetime. Here, we use numerical simulations of the Einstein equations to study the evolution of inflation-induced Higgs fluctuations as they grow towards the true (negative-energy) minimum. Our simulations show that forming a single patch of true vacuum in our past light cone during inflation is incompatible with the existence of our Universe; themore » boundary of the true vacuum region grows outward in a causally disconnected manner from the crunching interior, which forms a black hole. We also find that these black hole horizons may be arbitrarily elongated—even forming black strings—in violation of the hoop conjecture. Furthermore, by extending the numerical solution of the Fokker-Planck equation to the exponentially suppressed tails of the field distribution at large field values, we derive a rigorous correlation between a future measurement of the tensor-to-scalar ratio and the scale at which the Higgs potential must receive stabilizing corrections in order for the Universe to have survived inflation until today.« less

Properties of vacuum-evaporated boron films

NASA Technical Reports Server (NTRS)

Feakes, F.

1973-01-01

The work on the properties of thin boron films made by vacuum evaporation of elemental boron using an electron beam as the energy source is reported. The program aimed at characterizing the properties of vacuum evaporated films. The work was directed toward those variables considered to be important in affecting the tensile strength of the boron films. In general, the thickness of the films was less than 0.002 in. The temperature of the substrate on which the boron was condensed was found to be most important. Three distinctly different forms of boron deposit were produced. Although the transition temperature was not sharply defined, at substrate temperatures of less than approximately 600 deg C the boron deposits were amorphous to X-ray. If the substrate were highly polished, the deposits were black and mirror-like. For substrates with coefficients of thermal expansion close to that of boron, the deposits were then continuous and uncracked. The studies suggest that the potential continues to exist for film-type composites to have both high strength and high modulus.

Improving Vacuum Cleaners

NASA Technical Reports Server (NTRS)

1997-01-01

Under a Space Act Agreement between the Kirby company and Lewis Research Center, NASA technology was applied to a commercial vacuum cleaner product line. Kirby engineers were interested in advanced operational concepts, such as particle flow behavior and vibration, critical factors to improve vacuum cleaner performance. An evaluation of the company 1994 home care system, the Kirby G4, led to the refinement of the new G5 and future models. Under the cooperative agreement, Kirby had access to Lewis' holography equipment, which added insight into how long a vacuum cleaner fan would perform, as well as advanced computer software that can simulate the flow of air through fans. The collaboration resulted in several successes including fan blade redesign and continuing dialogue on how to improve air-flow traits in various nozzle designs.

Reception and study of lunar surface material in inert gas medium. [considering laboratory vacuum receiving chamber

NASA Technical Reports Server (NTRS)

Surkov, Y. A.; Rudnitskiy, Y. M.; Glotov, V. A.

1974-01-01

The reception and study of lunar material returned by the Luna 16 space station is described. The layout of a vacuum receiving chamber for working with material in a helium atmosphere is examined along with the main operations involved in extracting the material from the ampule and drill.

Switching Circuit for Shop Vacuum System

NASA Technical Reports Server (NTRS)

Burley, R. K.

1987-01-01

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

Vacuum Brazing of Accelerator Components

NASA Astrophysics Data System (ADS)

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

2012-11-01

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.

Wide band cryogenic ultra-high vacuum microwave absorber

DOEpatents

Campisi, I.E.

1992-05-12

An absorber waveguide assembly for absorbing higher order modes of microwave energy under cryogenic ultra-high vacuum conditions, that absorbs wide-band multi-mode energy. The absorber is of a special triangular shape, made from flat tiles of silicon carbide and aluminum nitride. The leading sharp end of the absorber is located in a corner of the waveguide and tapers to a larger cross-sectional area whose center is located approximately in the center of the wave guide. The absorber is relatively short, being of less height than the maximum width of the waveguide. 11 figs.

Wide band cryogenic ultra-high vacuum microwave absorber

DOEpatents

Campisi, Isidoro E.

1992-01-01

An absorber wave guide assembly for absorbing higher order modes of microwave energy under cryogenic ultra-high vacuum conditions, that absorbs wide-band multi-mode energy. The absorber is of a special triangular shape, made from flat tiles of silicon carbide and aluminum nitride. The leading sharp end of the absorber is located in a corner of the wave guide and tapers to a larger cross-sectional area whose center is located approximately in the center of the wave guide. The absorber is relatively short, being of less height than the maximum width of the wave guide.

Cosmological implications of quantum mechanics parametrization of dark energy

NASA Astrophysics Data System (ADS)

Szydłowski, Marek; Stachowski, Aleksander; Urbanowski, Krzysztof

2017-08-01

We consider the cosmology with the running dark energy. The parametrization of dark energy is derived from the quantum process of transition from the false vacuum state to the true vacuum state. This model is the generalized interacting CDM model. We consider the energy density of dark energy parametrization, which is given by the Breit-Wigner energy distribution function. The idea of the process of the quantum mechanical decay of unstable states was formulated by Krauss and Dent. We used this idea in our considerations. In this model is an energy transfer in the dark sector. In this evolutional scenario the universe starts from the false vacuum state and goes to the true vacuum state of the present day universe. The intermediate regime during the passage from false to true vacuum states takes place. In this way the cosmological constant problem can be tried to solve. We estimate the cosmological parameters for this model. This model is in a good agreement with the astronomical data and is practically indistinguishable from CDM model.

Aluminum/vacuum multilayer configuration for spatial high-energy electron shielding via electron return effects induced by magnetic field.

PubMed

Chen, Tuo; Tang, Xiaobin; Chen, Feida; Ni, Minxuan; Huang, Hai; Zhang, Yun; Chen, Da

2017-06-26

Radiation shielding of high-energy electrons is critical for successful space missions. However, conventional passive shielding systems exhibit several limitations, such as heavy configuration, poor shielding ability, and strong secondary bremsstrahlung radiation. In this work, an aluminum/vacuum multilayer structure was proposed based on the electron return effects induced by magnetic field. The shielding property of several configurations was evaluated by using the Monte Carlo method. Results showed that multilayer systems presented improved shielding ability to electrons, and less secondary x-ray transmissions than those of conventional systems. Moreover, the influences of magnetic flux density and number of layers on the shielding property of multilayer systems were investigated using a female Chinese hybrid reference phantom based on cumulative dose. In the case of two aluminum layers, the cumulative dose in a phantom gradually decreased with increasing magnetic flux density. The maximum decline rate was found within 0.4-1 Tesla. With increasing layers of configuration, the cumulative dose decreased and the shielding ability improved. This research provides effective shielding measures for future space radiation protection in high-energy electron environments.

Influence of the axial magnetic field on sheath development after current zero in a vacuum circuit breaker

NASA Astrophysics Data System (ADS)

Chen, Yi; Yang, Fei; Sun, Hao; Wu, Yi; Niu, Chunping; Rong, Mingzhe

2017-06-01

After current zero, which is the moment when the vacuum circuit breaker interrupts a vacuum arc, sheath development is the first process in the dielectric recovery process. An axial magnetic field (AMF) is widely used in the vacuum circuit breaker when the high-current vacuum arc is interrupted. Therefore, it is very important to study the influence of different AMF amplitudes on the sheath development. The objective of this paper is to study the influence of different AMF amplitudes on the sheath development from a micro perspective. Thus, the particle in cell-Monte Carlo collisions (PIC-MCC) method was adopted to develop the sheath development model. We compared the simulation results with the experimental results and then validated the simulation. We also obtained the speed of the sheath development and the energy density of the ions under different AMF amplitudes. The results showed that the larger the AMF amplitudes are, the faster the sheath develops and the lower the ion energy density is, meaning the breakdown is correspondingly more difficult.

Thick SS316 materials TIG welding development activities towards advanced fusion reactor vacuum vessel applications

NASA Astrophysics Data System (ADS)

Kumar, B. Ramesh; Gangradey, R.

2012-11-01

Advanced fusion reactors like ITER and up coming Indian DEMO devices are having challenges in terms of their materials design and fabrication procedures. The operation of these devices is having various loads like structural, thermo-mechanical and neutron irradiation effects on major systems like vacuum vessel, divertor, magnets and blanket modules. The concept of double wall vacuum vessel (VV) is proposed in view of protecting of major reactor subsystems like super conducting magnets, diagnostic systems and other critical components from high energy 14 MeV neutrons generated from fusion plasma produced by D-T reactions. The double walled vacuum vessel is used in combination with pressurized water circulation and some special grade borated steel blocks to shield these high energy neutrons effectively. The fabrication of sub components in VV are mainly used with high thickness SS materials in range of 20 mm- 60 mm of various grades based on the required protocols. The structural components of double wall vacuum vessel uses various parts like shields, ribs, shells and diagnostic vacuum ports. These components are to be developed with various welding techniques like TIG welding, Narrow gap TIG welding, Laser welding, Hybrid TIG laser welding, Electron beam welding based on requirement. In the present paper the samples of 20 mm and 40 mm thick SS 316 materials are developed with TIG welding process and their mechanical properties characterization with Tensile, Bend tests and Impact tests are carried out. In addition Vickers hardness tests and microstructural properties of Base metal, Heat Affected Zone (HAZ) and Weld Zone are done. TIG welding application with high thick SS materials in connection with vacuum vessel requirements and involved criticalities towards welding process are highlighted.

Vacuum energy density fluctuations in Minkowski and Casimir states via smeared quantum fields and point separation

NASA Astrophysics Data System (ADS)

Phillips, Nicholas G.; Hu, B. L.

2000-10-01

We present calculations of the variance of fluctuations and of the mean of the energy momentum tensor of a massless scalar field for the Minkowski and Casimir vacua as a function of an intrinsic scale defined by a smeared field or by point separation. We point out that, contrary to prior claims, the ratio of variance to mean-squared being of the order unity is not necessarily a good criterion for measuring the invalidity of semiclassical gravity. For the Casimir topology we obtain expressions for the variance to mean-squared ratio as a function of the intrinsic scale (defined by a smeared field) compared to the extrinsic scale (defined by the separation of the plates, or the periodicity of space). Our results make it possible to identify the spatial extent where negative energy density prevails which could be useful for studying quantum field effects in worm holes and baby universes, and for examining the design feasibility of real-life ``time machines.'' For the Minkowski vacuum we find that the ratio of the variance to the mean-squared, calculated from the coincidence limit, is identical to the value of the Casimir case at the same limit for spatial point separation while identical to the value of a hot flat space result with a temporal point separation. We analyze the origin of divergences in the fluctuations of the energy density and discuss choices in formulating a procedure for their removal, thus raising new questions about the uniqueness and even the very meaning of regularization of the energy momentum tensor for quantum fields in curved or even flat spacetimes when spacetime is viewed as having an extended structure.

Investigation of Dielectric Breakdown Characteristics for Double-break Vacuum Interrupter and Dielectric Breakdown Probability Distribution in Vacuum Interrupter

NASA Astrophysics Data System (ADS)

Shioiri, Tetsu; Asari, Naoki; Sato, Junichi; Sasage, Kosuke; Yokokura, Kunio; Homma, Mitsutaka; Suzuki, Katsumi

To investigate the reliability of equipment of vacuum insulation, a study was carried out to clarify breakdown probability distributions in vacuum gap. Further, a double-break vacuum circuit breaker was investigated for breakdown probability distribution. The test results show that the breakdown probability distribution of the vacuum gap can be represented by a Weibull distribution using a location parameter, which shows the voltage that permits a zero breakdown probability. The location parameter obtained from Weibull plot depends on electrode area. The shape parameter obtained from Weibull plot of vacuum gap was 10∼14, and is constant irrespective non-uniform field factor. The breakdown probability distribution after no-load switching can be represented by Weibull distribution using a location parameter. The shape parameter after no-load switching was 6∼8.5, and is constant, irrespective of gap length. This indicates that the scatter of breakdown voltage was increased by no-load switching. If the vacuum circuit breaker uses a double break, breakdown probability at low voltage becomes lower than single-break probability. Although potential distribution is a concern in the double-break vacuum cuicuit breaker, its insulation reliability is better than that of the single-break vacuum interrupter even if the bias of the vacuum interrupter's sharing voltage is taken into account.

Utilization of coincidence criteria in absolute length measurements by optical interferometry in vacuum and air

NASA Astrophysics Data System (ADS)

Schödel, R.

2015-08-01

Traceability of length measurements to the international system of units (SI) can be realized by using optical interferometry making use of well-known frequencies of monochromatic light sources mentioned in the Mise en Pratique for the realization of the metre. At some national metrology institutes, such as Physikalisch-Technische Bundesanstalt (PTB) in Germany, the absolute length of prismatic bodies (e.g. gauge blocks) is realized by so-called gauge-block interference comparators. At PTB, a number of such imaging phase-stepping interference comparators exist, including specialized vacuum interference comparators, each equipped with three highly stabilized laser light sources. The length of a material measure is expressed as a multiple of each wavelength. The large number of integer interference orders can be extracted by the method of exact fractions in which the coincidence of the lengths resulting from the different wavelengths is utilized as a criterion. The unambiguous extraction of the integer interference orders is an essential prerequisite for correct length measurements. This paper critically discusses coincidence criteria and their validity for three modes of absolute length measurements: 1) measurements under vacuum in which the wavelengths can be identified with the vacuum wavelengths, 2) measurements under air in which the air refractive index is obtained from environmental parameters using an empirical equation, and 3) measurements under air in which the air refractive index is obtained interferometrically by utilizing a vacuum cell placed along the measurement pathway. For case 3), which corresponds to PTB’s Kösters-Comparator for long gauge blocks, the unambiguous determination of integer interference orders related to the air refractive index could be improved by about a factor of ten when an ‘overall dispersion value,’ suggested in this paper, is used as coincidence criterion.

Investigation of the cylindrical vacuum hohlraum energy in the first implosion experiment at the SGIII laser facility

NASA Astrophysics Data System (ADS)

Zhang, Huasen; Jiang, Wei; Ge, Fengjun; Song, Peng; Zou, Shiyang; Huang, Tianxuan; Li, Sanwei; Yang, Dong; Li, Zhichao; Hou, Lifei; Guo, Liang; Che, Xingsen; Du, Huabing; Xie, Xufei; He, Xiaoan; Li, Chaoguang; Zha, Weiyi; Xu, Tao; Liu, Yonggang; Wei, Huiyue; Liu, Xiangming; Chen, Zhongjing; Zhang, Xing; Yan, Ji; Pu, Yudong; Peng, Xiaoshi; Li, Yulong; Gu, Peijun; Zheng, Wudi; Liu, Jie; Ding, Yongkun; Zhu, Shaoping

2018-02-01

The cylindrical vacuum hohlraum energy at the SGIII laser facility [X. T. He and W. Y. Zhang, Eur. Phys. J. D 44, 227 (2007) and W. Zheng et al., High Power Laser Sci. Eng. 4, e21 (2016)] is investigated for the first time. The hohlraum size and the laser energy are intermediate between the Nova and NIF typical hohlraum experiments. It is found that the SGIII hohlraum exhibits an x-ray conversion efficiency of about 85%, which is more close to that of the NIF hohlraum. The LARED simulations of the SGIII hohlraum underestimate about 15% of the radiation flux measured from the laser entrance hole, while the capsule radiation drive inferred from the x-ray bangtime is roughly consistent with the experiments. The underestimation of the SGIII hohlraum radiation flux is mainly caused by the more enclosed laser entrance hole in the LARED simulation. The comparison between the SGIII and NIF hohlraum simulations by LARED indicates that the LARED generally underestimates the measured radiation flux by 15% for the high x-ray conversion efficiency hohlraums, while it can roughly predict the capsule radiation drive inside the hohlraum.

Vacuum-insulated catalytic converter

DOEpatents

Benson, David K.

2001-01-01

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.

Vacuum-Induction, Vacuum-Arc, and Air-Induction Melting of a Complex Heat-Resistant Alloy

NASA Technical Reports Server (NTRS)

Decker, R. F.; Rowe, John P.; Freeman, J. W.

1959-01-01

The relative hot-workability and creep-rupture properties at 1600 F of a complex 55Ni-20Cr-15Co-4Mo-3Ti-3Al alloy were evaluated for vacuum-induction, vacuum-arc, and air-induction melting. A limited study of the role of oxygen and nitrogen and the structural effects in the alloy associated with the melting process was carried out. The results showed that the level of boron and/or zirconium was far more influential on properties than the melting method. Vacuum melting did reduce corner cracking and improve surface during hot-rolling. It also resulted in more uniform properties within heats. The creep-rupture properties were slightly superior in vacuum heats at low boron plus zirconium or in heats with zirconium. There was little advantage at high boron levels and air heats were superior at high levels of boron plus zirconium. Vacuum heats also had fewer oxide and carbonitride inclusions although this was a function of the opportunity for separation of the inclusions from high oxygen plus nitrogen heats. The removal of phosphorous by vacuum melting was not found to be related to properties. Oxygen plus nitrogen appeared to increase ductility in creep-rupture tests suggesting that vacuum melting removes unidentified elements detrimental to ductility. Oxides and carbonitrides in themselves did not initiate microcracks. Carbonitrides in the grain boundaries of air heats did initiate microcracks. The role of microcracking from this source and as a function of oxygen and nitrogen content was not clear. Oxygen and nitrogen did intensify corner cracking during hot-rolling but were not responsible for poor surface which resulted from rolling heats melted in air.

Wireless Integrated Microelectronic Vacuum Sensor System

NASA Technical Reports Server (NTRS)

Krug, Eric; Philpot, Brian; Trott, Aaron; Lawrence, Shaun

2013-01-01

NASA Stennis Space Center's (SSC's) large rocket engine test facility requires the use of liquid propellants, including the use of cryogenic fluids like liquid hydrogen as fuel, and liquid oxygen as an oxidizer (gases which have been liquefied at very low temperatures). These fluids require special handling, storage, and transfer technology. The biggest problem associated with transferring cryogenic liquids is product loss due to heat transfer. Vacuum jacketed piping is specifically designed to maintain high thermal efficiency so that cryogenic liquids can be transferred with minimal heat transfer. A vacuum jacketed pipe is essentially two pipes in one. There is an inner carrier pipe, in which the cryogenic liquid is actually transferred, and an outer jacket pipe that supports and seals the vacuum insulation, forming the "vacuum jacket." The integrity of the vacuum jacketed transmission lines that transfer the cryogenic fluid from delivery barges to the test stand must be maintained prior to and during engine testing. To monitor the vacuum in these vacuum jacketed transmission lines, vacuum gauge readings are used. At SSC, vacuum gauge measurements are done on a manual rotation basis with two technicians, each using a handheld instrument. Manual collection of vacuum data is labor intensive and uses valuable personnel time. Additionally, there are times when personnel cannot collect the data in a timely fashion (i.e., when a leak is detected, measurements must be taken more often). Additionally, distribution of this data to all interested parties can be cumbersome. To simplify the vacuum-gauge data collection process, automate the data collection, and decrease the labor costs associated with acquiring these measurements, an automated system that monitors the existing gauges was developed by Invocon, Inc. For this project, Invocon developed a Wireless Integrated Microelectronic Vacuum Sensor System (WIMVSS) that provides the ability to gather vacuum

Using Microwaves for Extracting Water from the Moon

NASA Technical Reports Server (NTRS)

Ethridge, Edwin C.

2009-01-01

Twenty years ago, the Lunar Prospector remote sensing satellite provided evidence of relatively large hydrogen concentrations at the lunar poles and in particular concentrated in permanently shadowed craters. The scientific hypothesis is that the hydrogen is in the form of cryo-trapped water just under the surface of the soil. If true this would mean that an average of about 2% water ice is mixed with the lunar soil existing in the form of ice at cryogenic temperatures. For 5 years we have been investigating the use of microwaves for the processing of lunar soil. One of the early uses could be to use microwave energy to extract volatiles and in particular water from the lunar permafrost. Prototype experiments have shown that microwave energy at 2.45 GHz, as in consumer microwave ovens, will couple with and heat cryogenically cooled lunar soil permafrost simulant, resulting in the rapid sublimation of water vapor into the vacuum chamber. The water vapor has been collected on a cryogenic cold trap with high efficiency. The primary advantage of microwave processing is that the volatiles can be extracted in situ. Excavation would not be required. Microwave frequency dielectric property measurements are being made of different lunar soil simulants and plans are to measure Apollo lunar soil at different frequencies and over a range of temperatures. The materials properties are being used to evaluate the heating of lunar soil and develop COMSOL models that can be used to evaluate different microwave extraction scenarios. With COMSOL the heating from cryogenic temperatures can be calculated and COMSOL will permit temperature dependent materials properties to be used during the heating process. Calculations at different microwave frequencies will allow the evaluation of the type of hardware that would be needed to most efficiently extract the water and other volatiles.

Vacuum-driven power-free microfluidics utilizing the gas solubility or permeability of polydimethylsiloxane (PDMS).

PubMed

Xu, Linfeng; Lee, Hun; Jetta, Deekshitha; Oh, Kwang W

2015-10-21

Suitable pumping methods for flow control remain a major technical hurdle in the path of biomedical microfluidic systems for point-of-care (POC) diagnostics. A vacuum-driven power-free micropumping method provides a promising solution to such a challenge. In this review, we focus on vacuum-driven power-free microfluidics based on the gas solubility or permeability of polydimethylsiloxane (PDMS); degassed PDMS can restore air inside itself due to its high gas solubility or gas permeable nature. PDMS allows the transfer of air into a vacuum through it due to its high gas permeability. Therefore, it is possible to store or transfer air into or through the gas soluble or permeable PDMS in order to withdraw liquids into the embedded dead-end microfluidic channels. This article provides a comprehensive look at the physics of the gas solubility and permeability of PDMS, a systematic review of different types of vacuum-driven power-free microfluidics, and guidelines for designing solubility-based or permeability-based PDMS devices, alongside existing applications. Advanced topics and the outlook in using micropumping that utilizes the gas solubility or permeability of PDMS will be also discussed. We strongly recommend that microfluidics and lab-on-chip (LOC) communities harness vacuum energy to develop smart vacuum-driven microfluidic systems.

Energy extraction from atmospheric turbulence to improve flight vehicle performance

NASA Astrophysics Data System (ADS)

Patel, Chinmay Karsandas

Small 'bird-sized' Unmanned Aerial Vehicles (UAVs) have now become practical due to technological advances in embedded electronics, miniature sensors and actuators, and propulsion systems. Birds are known to take advantage of wind currents to conserve energy and fly long distances without flapping their wings. This dissertation explores the possibility of improving the performance of small UAVs by extracting the energy available in atmospheric turbulence. An aircraft can gain energy from vertical gusts by increasing its lift in regions of updraft and reducing its lift in downdrafts - a concept that has been known for decades. Starting with a simple model of a glider flying through a sinusoidal gust, a parametric optimization approach is used to compute the minimum gust amplitude and optimal control input required for the glider to sustain flight without losing energy. For small UAVs using optimal control inputs, sinusoidal gusts with amplitude of 10--15% of the cruise speed are sufficient to keep the aircraft aloft. The method is then modified and extended to include random gusts that are representative of natural turbulence. A procedure to design optimal control laws for energy extraction from realistic gust profiles is developed using a Genetic Algorithm (GA). A feedback control law is designed to perform well over a variety of random gusts, and not be tailored for one particular gust. A small UAV flying in vertical turbulence is shown to obtain average energy savings of 35--40% with the use of a simple control law. The design procedure is also extended to determine optimal control laws for sinusoidal as well as turbulent lateral gusts. The theoretical work is complemented by experimental validation using a small autonomous UAV. The development of a lightweight autopilot and UAV platform is presented. Flight test results show that active control of the lift of an autonomous glider resulted in approximately 46% average energy savings compared to glides with fixed

14 CFR 29.1433 - Vacuum systems.

Code of Federal Regulations, 2010 CFR

2010-01-01

... STANDARDS: TRANSPORT CATEGORY ROTORCRAFT Equipment Miscellaneous Equipment § 29.1433 Vacuum systems. (a... the discharge lines from the vacuum air pump when the delivery temperature of the air becomes unsafe. (b) Each vacuum air system line and fitting on the discharge side of the pump that might contain...

Vacuum Technology Considerations For Mass Metrology

PubMed Central

Abbott, Patrick J.; Jabour, Zeina J.

2011-01-01

Vacuum weighing of mass artifacts eliminates the necessity of air buoyancy correction and its contribution to the measurement uncertainty. Vacuum weighing is also an important process in the experiments currently underway for the redefinition of the SI mass unit, the kilogram. Creating the optimum vacuum environment for mass metrology requires careful design and selection of construction materials, plumbing components, pumping, and pressure gauging technologies. We review the vacuum technology1 required for mass metrology and suggest procedures and hardware for successful and reproducible operation. PMID:26989593

Gas propagation in a liquid helium cooled vacuum tube following a sudden vacuum loss

NASA Astrophysics Data System (ADS)

Dhuley, Ram C.

This dissertation describes the propagation of near atmospheric nitrogen gas that rushes into a liquid helium cooled vacuum tube after the tube suddenly loses vacuum. The loss-of-vacuum scenario resembles accidental venting of atmospheric air to the beam-line of a superconducting radio frequency particle accelerator and is investigated to understand how in the presence of condensation, the in-flowing air will propagate in such geometry. In a series of controlled experiments, room temperature nitrogen gas (a substitute for air) at a variety of mass flow rates was vented to a high vacuum tube immersed in a bath of liquid helium. Pressure probes and thermometers installed on the tube along its length measured respectively the tube pressure and tube wall temperature rise due to gas flooding and condensation. At high mass in-flow rates a gas front propagated down the vacuum tube but with a continuously decreasing speed. Regression analysis of the measured front arrival times indicates that the speed decreases nearly exponentially with the travel length. At low enough mass in-flow rates, no front propagated in the vacuum tube. Instead, the in-flowing gas steadily condensed over a short section of the tube near its entrance and the front appeared to `freeze-out'. An analytical expression is derived for gas front propagation speed in a vacuum tube in the presence of condensation. The analytical model qualitatively explains the front deceleration and flow freeze-out. The model is then simplified and supplemented with condensation heat/mass transfer data to again find the front to decelerate exponentially while going away from the tube entrance. Within the experimental and procedural uncertainty, the exponential decay length-scales obtained from the front arrival time regression and from the simplified model agree.

Developing a vacuum cooking equipment prototype to produce strawberry jam and optimization of vacuum cooking conditions.

PubMed

Okut, Dilara; Devseren, Esra; Koç, Mehmet; Ocak, Özgül Özdestan; Karataş, Haluk; Kaymak-Ertekin, Figen

2018-01-01

Purpose of this study was to develop prototype cooking equipment that can work at reduced pressure and to evaluate its performance for production of strawberry jam. The effect of vacuum cooking conditions on color soluble solid content, reducing sugars total sugars HMF and sensory properties were investigated. Also, the optimum vacuum cooking conditions for strawberry jam were optimized for Composite Rotatable Design. The optimum cooking temperature and time were determined targeting maximum soluble solid content and sensory attributes (consistency) and minimum Hue value and HMF content. The optimum vacuum cooking conditions determined were 74.4 °C temperature and 19.8 time. The soluble solid content strawberry jam made by vacuum process were similar to those prepared by traditional method. HMF contents of jams produced with vacuum cooking method were well within limit of standards.

14 CFR 29.1433 - Vacuum systems.

Code of Federal Regulations, 2014 CFR

2014-01-01

... 14 Aeronautics and Space 1 2014-01-01 2014-01-01 false Vacuum systems. 29.1433 Section 29.1433... STANDARDS: TRANSPORT CATEGORY ROTORCRAFT Equipment Miscellaneous Equipment § 29.1433 Vacuum systems. (a.... (b) Each vacuum air system line and fitting on the discharge side of the pump that might contain...

Vacuum status-display and sector-conditioning programs

NASA Astrophysics Data System (ADS)

Skelly, J.; Yen, S.

1990-08-01

Two programs have been developed for observation and control of the AGS vacuum system, which include the following notable features: (1) they incorporate a graphical user interface and (2) they are driven by a relational database which describes the vacuum system. The vacuum system comprises some 440 devices organized into 28 vacuum sectors. The status-display program invites menu selection of a sector, interrogates the relational database for relevant vacuum devices, acquires live readbacks and posts a graphical display of their status. The sector-conditioning program likewise invites sector selection, produces the same status display and also implements process control logic on the sector devices to pump the sector down from atmospheric pressure to high vacuum over a period extending several hours. As additional devices are installed in the vacuum system, the devices are added to the relational database; these programs then automatically include the new devices.

First High-Convergence Cryogenic Implosion in a Near-Vacuum Hohlraum

NASA Astrophysics Data System (ADS)

Berzak Hopkins, L. F.; Meezan, N. B.; Le Pape, S.; Divol, L.; Mackinnon, A. J.; Ho, D. D.; Hohenberger, M.; Jones, O. S.; Kyrala, G.; Milovich, J. L.; Pak, A.; Ralph, J. E.; Ross, J. S.; Benedetti, L. R.; Biener, J.; Bionta, R.; Bond, E.; Bradley, D.; Caggiano, J.; Callahan, D.; Cerjan, C.; Church, J.; Clark, D.; Döppner, T.; Dylla-Spears, R.; Eckart, M.; Edgell, D.; Field, J.; Fittinghoff, D. N.; Gatu Johnson, M.; Grim, G.; Guler, N.; Haan, S.; Hamza, A.; Hartouni, E. P.; Hatarik, R.; Herrmann, H. W.; Hinkel, D.; Hoover, D.; Huang, H.; Izumi, N.; Khan, S.; Kozioziemski, B.; Kroll, J.; Ma, T.; MacPhee, A.; McNaney, J.; Merrill, F.; Moody, J.; Nikroo, A.; Patel, P.; Robey, H. F.; Rygg, J. R.; Sater, J.; Sayre, D.; Schneider, M.; Sepke, S.; Stadermann, M.; Stoeffl, W.; Thomas, C.; Town, R. P. J.; Volegov, P. L.; Wild, C.; Wilde, C.; Woerner, E.; Yeamans, C.; Yoxall, B.; Kilkenny, J.; Landen, O. L.; Hsing, W.; Edwards, M. J.

2015-05-01

Recent experiments on the National Ignition Facility [M. J. Edwards et al., Phys. Plasmas 20, 070501 (2013)] demonstrate that utilizing a near-vacuum hohlraum (low pressure gas-filled) is a viable option for high convergence cryogenic deuterium-tritium (DT) layered capsule implosions. This is made possible by using a dense ablator (high-density carbon), which shortens the drive duration needed to achieve high convergence: a measured 40% higher hohlraum efficiency than typical gas-filled hohlraums, which requires less laser energy going into the hohlraum, and an observed better symmetry control than anticipated by standard hydrodynamics simulations. The first series of near-vacuum hohlraum experiments culminated in a 6.8 ns, 1.2 MJ laser pulse driving a 2-shock, high adiabat (α ˜3.5 ) cryogenic DT layered high density carbon capsule. This resulted in one of the best performances so far on the NIF relative to laser energy, with a measured primary neutron yield of 1.8 ×1015 neutrons, with 20% calculated alpha heating at convergence ˜27 × .

First high-convergence cryogenic implosion in a near-vacuum hohlraum

DOE PAGES

Berzak Hopkins, L.  F.; Meezan, N.  B.; Le Pape, S.; ...

2015-04-29

Recent experiments on the National Ignition Facility [M. J. Edwards et al., Phys. Plasmas 20, 070501 (2013)] demonstrate that utilizing a near-vacuum hohlraum (low pressure gas-filled) is a viable option for high convergence cryogenic deuterium-tritium (DT) layered capsule implosions. This is made possible by using a dense ablator (high-density carbon), which shortens the drive duration needed to achieve high convergence: a measured 40% higher hohlraum efficiency than typical gas-filled hohlraums, which requires less laser energy going into the hohlraum, and an observed better symmetry control than anticipated by standard hydrodynamics simulations. The first series of near-vacuum hohlraum experiments culminated inmore » a 6.8 ns, 1.2 MJ laser pulse driving a 2-shock, high adiabat (α ~ 3.5) cryogenic DT layered high density carbon capsule. This resulted in one of the best performances so far on the NIF relative to laser energy, with a measured primary neutron yield of 1.8 X 10¹⁵ neutrons, with 20% calculated alpha heating at convergence ~27X.« less

Working in a Vacuum

ERIC Educational Resources Information Center

Rathey, Allen

2005-01-01

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)…

Arsenic interactions with a fullerene-like BN cage in the vacuum and aqueous phase.

PubMed

Beheshtian, Javad; Peyghan, Ali Ahmadi; Bagheri, Zargham

2013-02-01

Adsorption of arsenic ions, As (III and V), on the surface of fullerene-like B(12)N(12) cage has been explored in vacuum and aqueous phase using density functional theory in terms of Gibbs free energies, enthalpies, geometry, and density of state analysis. It was found that these ions can be strongly chemisorbed on the surface of the cluster in both vacuum and aqueous phase, resulting in significant changes in its electronic properties so that the cluster transforms from a semi-insulator to a semiconductor. The solvent significantly affects the geometry parameters and electronic properties of the As/B(12)N(12) complexes and the interaction between components is considerably weaker in the aqueous phase than that in the vacuum.

Effect of a hawthorn extract on contraction and energy turnover of isolated rat cardiomyocytes.

PubMed

Pöpping, S; Rose, H; Ionescu, I; Fischer, Y; Kammermeier, H

1995-11-01

The hawthorn extract LI 132 (crataegus), prepared from leaves and flowers, and standardised to 2.2% flavonoids, was investigated with respect to its effect on (1) the contraction, (2) the energy-turnover and (3) the apparent refractory period (t(ref)) of isolated cardiac myocytes from adult rats. (1) The contractile behaviour of attached myocytes was analyzed by an image processing system. (2) The energy turnover was calculated from the decrease in oxygen content in the myocyte suspension, brought about by cellular respiration. It was differentiated between energy turnover related to cell shortening and that required for ionic transport processes by application of the contraction-inhibiting agent 2,3-butanedione monoxime. (3) The apparent refractory period (t(ref)) was evaluated by pacing the myocytes with increasing stimulation rates and determining the frequency at which failure of single contractions occurred. For these purposes, the myocytes were incubated in a stimulation chamber, which is part of a computer-assisted system allowing to simultaneously evaluate the mechanics and energetics of electrically induced contraction. Within a range of 30-180 microg/ml, the hawthorn extract exhibited a positive inotropic effect on the contraction amplitude accompanied by a moderate increase of energy turnover both for mechanical and ionic processes. In comparison with other positive inotropic interventions, such as application of the beta-adrenergic agonist isoprenaline, or of the cardiac glycoside ouabain (g-strophantin), or elevation of the extracellular Ca++-concentration, the effects of the hawthorn extract were significantly more economical with respect to the energetics of the myocytes. Furthermore the extract prolonged the apparent refractory period in the presence and the absence of isoprenaline, which be indicative for an antiarrhythmic potential.

Comparative Recovery of Two Human Norovirus Surrogates, Feline Calicivirus and Murine Norovirus, with a Wet Vacuum System, Macrofoam-Tipped Swab, and Bottle Extraction Method from Carpets.

PubMed

Buckley, David; Fraser, Angela; Pettigrew, Charles; Anderson, Jeffery; Jiang, Xiuping

2018-05-10

Human noroviruses (HuNoV) are the leading cause of known foodborne illness in the United States, but direct detection during outbreak investigations is challenging. On the other hand, sampling both hard and soft environmental surfaces can be used to improve outbreak investigations. Currently, we lack virus recovery methods for soft surfaces, such as carpet, despite evidence suggesting that carpets contribute to HuNoV outbreaks. Our aim was to compare two recovery methods, wet vacuum and swabbing, for routine carpet sampling of HuNoV against a laboratory reference method known as bottle extraction (BE). Specifically, we compared the microbial vacuum (MVAC), macrofoam-tipped swab (MS), and BE by using HuNoV surrogates, feline calicivirus (FCV) and murine norovirus (MNV), inoculated on wool and nylon carpet carriers. The highest recovery of infectious FCV from wool was 5.51, 3.76, and 5.16 log PFU, whereas on nylon, recovery was 5.03, 3.62, and 4.75 log PFU by using BE, MS, and MVAC, respectively. On the other hand, the highest recovery of infectious MNV from wool was 6.10, 4.50, and 5.99 log PFU, while recovery on nylon was 6.07, 4.58, and 6.13 log PFU by using BE, MS, and MVAC, respectively. Significantly more PFU and genomic copies were recovered by using BE and MVAC compared with MS, while buffer type played a significant role in recovery of infectious FCV.

Vacuum space charge effects in sub-picosecond soft X-ray photoemission on a molecular adsorbate layer

DOE PAGES

Dell'Angela, M.; Anniyev, T.; Beye, M.; ...

2015-03-01

Vacuum space charge-induced kinetic energy shifts of O 1s and Ru 3d core levels in femtosecond soft X-ray photoemission spectra (PES) have been studied at a free electron laser (FEL) for an oxygen layer on Ru(0001). We fully reproduced the measurements by simulating the in-vacuum expansion of the photoelectrons and demonstrate the space charge contribution of the high-order harmonics in the FEL beam. Employing the same analysis for 400 nm pump-X-ray probe PES, we can disentangle the delay dependent Ru 3d energy shifts into effects induced by space charge and by lattice heating from the femtosecond pump pulse.

Vacuum space charge effects in sub-picosecond soft X-ray photoemission on a molecular adsorbate layer.

PubMed

Dell'Angela, M; Anniyev, T; Beye, M; Coffee, R; Föhlisch, A; Gladh, J; Kaya, S; Katayama, T; Krupin, O; Nilsson, A; Nordlund, D; Schlotter, W F; Sellberg, J A; Sorgenfrei, F; Turner, J J; Öström, H; Ogasawara, H; Wolf, M; Wurth, W

2015-03-01

Vacuum space charge induced kinetic energy shifts of O 1s and Ru 3d core levels in femtosecond soft X-ray photoemission spectra (PES) have been studied at a free electron laser (FEL) for an oxygen layer on Ru(0001). We fully reproduced the measurements by simulating the in-vacuum expansion of the photoelectrons and demonstrate the space charge contribution of the high-order harmonics in the FEL beam. Employing the same analysis for 400 nm pump-X-ray probe PES, we can disentangle the delay dependent Ru 3d energy shifts into effects induced by space charge and by lattice heating from the femtosecond pump pulse.

A Rigorous Treatment of Energy Extraction from a Rotating Black Hole

NASA Astrophysics Data System (ADS)

Finster, F.; Kamran, N.; Smoller, J.; Yau, S.-T.

2009-05-01

The Cauchy problem is considered for the scalar wave equation in the Kerr geometry. We prove that by choosing a suitable wave packet as initial data, one can extract energy from the black hole, thereby putting supperradiance, the wave analogue of the Penrose process, into a rigorous mathematical framework. We quantify the maximal energy gain. We also compute the infinitesimal change of mass and angular momentum of the black hole, in agreement with Christodoulou’s result for the Penrose process. The main mathematical tool is our previously derived integral representation of the wave propagator.

Quantum vacuum noise in physics and cosmology.

PubMed

Davies, P. C. W.

2001-09-01

The concept of the vacuum in quantum field theory is a subtle one. Vacuum states have a rich and complex set of properties that produce distinctive, though usually exceedingly small, physical effects. Quantum vacuum noise is familiar in optical and electronic devices, but in this paper I wish to consider extending the discussion to systems in which gravitation, or large accelerations, are important. This leads to the prediction of vacuum friction: The quantum vacuum can act in a manner reminiscent of a viscous fluid. One result is that rapidly changing gravitational fields can create particles from the vacuum, and in turn the backreaction on the gravitational dynamics operates like a damping force. I consider such effects in early universe cosmology and the theory of quantum black holes, including the possibility that the large-scale structure of the universe might be produced by quantum vacuum noise in an early inflationary phase. I also discuss the curious phenomenon that an observer who accelerates through a quantum vacuum perceives a bath of thermal radiation closely analogous to Hawking radiation from black holes, even though an inertial observer registers no particles. The effects predicted raise very deep and unresolved issues about the nature of quantum particles, the role of the observer, and the relationship between the quantum vacuum and the concepts of information and entropy. (c) 2001 American Institute of Physics.

Vacuum phonon tunneling.

PubMed

Altfeder, Igor; Voevodin, Andrey A; Roy, Ajit K

2010-10-15

Field-induced phonon tunneling, a previously unknown mechanism of interfacial thermal transport, has been revealed by ultrahigh vacuum inelastic scanning tunneling microscopy (STM). Using thermally broadened Fermi-Dirac distribution in the STM tip as in situ atomic-scale thermometer we found that thermal vibrations of the last tip atom are effectively transmitted to sample surface despite few angstroms wide vacuum gap. We show that phonon tunneling is driven by interfacial electric field and thermally vibrating image charges, and its rate is enhanced by surface electron-phonon interaction.

21 CFR 884.4340 - Fetal vacuum extractor.

Code of Federal Regulations, 2011 CFR

2011-04-01

... means of a suction cup attached to the scalp and is powered by an external vacuum source. This generic type of device may include the cup, hosing, vacuum source, and vacuum control. (b) Classification...

21 CFR 884.4340 - Fetal vacuum extractor.

Code of Federal Regulations, 2010 CFR

2010-04-01

... means of a suction cup attached to the scalp and is powered by an external vacuum source. This generic type of device may include the cup, hosing, vacuum source, and vacuum control. (b) Classification...

Characteristics of a large vacuum wave precursor on the SABRE voltage adder MITL and extraction ion diode

DOE Office of Scientific and Technical Information (OSTI.GOV)

Cuneo, M.E.; Hanson, D.L.; Menge, P.R.

SABRE (Sandia Accelerator and Beam Research Experiment) is a ten-cavity linear induction magnetically insulated voltage adder (6 MV, 300 kA) operated in positive polarity to investigate issues relevant to ion beam production and propagation for inertial confinement fusion. The voltage adder section is coupled to an applied-B extraction ion diode via a long coaxial output transmission line. Observations indicate that the power propagates in a vacuum wave prior to electron emission. After the electron emission threshold is reached, power propagates in a magnetically insulated wave. The precursor is observed to have a dominant impact on he turn-on, impedance history, andmore » beam characteristics of applied-B ion diodes since the precursor voltage is large enough to cause electron emission at the diode from both the cathode feed and cathode tips. The amplitude of the precursor at the load (3--4.5 MV) is a significant fraction of the maximum load voltage (5--6 MV) because (1) the transmission line gaps ( {approx} 9 cm at output) and therefore impedances are relatively large, and hence the electric field threshold for electron emission (200 to 300 kV/cm) is not reached until well into the power pulse rise time; and (2) the rapidly falling forward wave and diode impedance reduces the ratio of main pulse voltage to precursor voltage. Experimental voltage and current data from the transmission line and the ion diode will be presented and compared with TWOQUICK (2-D electromagnetic PIC code) simulations and analytic models.« less

Cold cathode vacuum gauging system

DOEpatents

Denny, Edward C.

2004-03-09

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.

Measurement of partial pressures in vacuum technology and vacuum physics

NASA Technical Reports Server (NTRS)

Huber, W. K.

1986-01-01

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

VACUUM TRAP AND VALVE COMBINATION

DOEpatents

Milleron, N.; Levenson, L.

1963-02-19

This patent relates to a vacuum trap and valve combination suitable for use in large ultra-high vacuum systems. The vacuum trap is a chamber having an inlet and outlet opening which may be made to communicate with a chamber to be evacuated and a diffusion pump, respectively. A valve is designed to hermeticaliy seal with inlet opening and, when opened, block the line-of- sight'' between the inlet and outlet openings, while allowing a large flow path between the opened vaive and the side walls of the trap. The interior of the trap and the side of the valve facing the inlet opening are covered with an impurity absorbent, such as Zeolite or activated aluminum. Besides the advantage of combining two components of a vacuum system into one, the present invention removes the need for a baffle between the pump and the chamber to be evacuated. In one use of a specific embodiment of this invention, the transmission probability was 45 and the partial pressure of the pump fluid vapor in the vacuum chamber was at least 100 times lower than its vapor pressure. (AEC)

Optimization of pectin extraction and antioxidant activities from Jerusalem artichoke

NASA Astrophysics Data System (ADS)

Liu, Shengyi; Shi, Xuejie; Xu, Lanlan; Yi, Yuetao

2016-03-01

Jerusalem artichoke is an economic crop widely planted in saline-alkaline soil. The use of Jerusalem artichoke is of great significance. In this study, the response surface method was employed to optimize the effects of processing variables (extraction temperature, pH, extraction time, and liquid-to-solid ratio) on the yield of Jerusalem artichoke pectin. Under the optimal extraction conditions: pH 1.52, 63.62 min, 100°C and a liquid-to-solid ratio of 44.4 mL/g, the maximum pectin yield was predicted to be 18.76%. Experiments were conducted under these optimal conditions and a pectin yield of 18.52±0.90% was obtained, which validated the model prediction. The effects of diff erent drying methods (freeze drying, spray drying and vacuum drying) on the properties of Jerusalem artichoke pectin were evaluated and they were compared with apple pectin. FTIR spectral analysis showed no major structural diff erences in Jerusalem artichoke pectin samples produced by various drying treatments. The antioxidant activities of pectin dried by diff erent methods were investigated using in vitro hydroxyl and DPPH radical scavenging systems. The results revealed that the activities of spray dried pectin (SDP) and apple pectin (AP) were stronger than those of vacuum oven dried pectin (ODP) and vacuum freeze dried pectin (FDP). Therefore compared with the other two drying methods, the spray drying method was the best.

Vacuum enhanced cutaneous biopsy instrument

DOEpatents

Collins, Joseph

2000-01-01

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.

Incipient fault feature extraction of rolling bearings based on the MVMD and Teager energy operator.

PubMed

Ma, Jun; Wu, Jiande; Wang, Xiaodong

2018-06-04

Aiming at the problems that the incipient fault of rolling bearings is difficult to recognize and the number of intrinsic mode functions (IMFs) decomposed by variational mode decomposition (VMD) must be set in advance and can not be adaptively selected, taking full advantages of the adaptive segmentation of scale spectrum and Teager energy operator (TEO) demodulation, a new method for early fault feature extraction of rolling bearings based on the modified VMD and Teager energy operator (MVMD-TEO) is proposed. Firstly, the vibration signal of rolling bearings is analyzed by adaptive scale space spectrum segmentation to obtain the spectrum segmentation support boundary, and then the number K of IMFs decomposed by VMD is adaptively determined. Secondly, the original vibration signal is adaptively decomposed into K IMFs, and the effective IMF components are extracted based on the correlation coefficient criterion. Finally, the Teager energy spectrum of the reconstructed signal of the effective IMF components is calculated by the TEO, and then the early fault features of rolling bearings are extracted to realize the fault identification and location. Comparative experiments of the proposed method and the existing fault feature extraction method based on Local Mean Decomposition and Teager energy operator (LMD-TEO) have been implemented using experimental data-sets and a measured data-set. The results of comparative experiments in three application cases show that the presented method can achieve a fairly or slightly better performance than LMD-TEO method, and the validity and feasibility of the proposed method are proved. Copyright © 2018. Published by Elsevier Ltd.

Troubleshooting crude vacuum tower overhead ejector systems

DOE Office of Scientific and Technical Information (OSTI.GOV)

Lines, J.R.; Frens, L.L.

1995-03-01

Routinely surveying tower overhead vacuum systems can improve performance and product quality. These vacuum systems normally provide reliable and consistent operation. However, process conditions, supplied utilities, corrosion, erosion and fouling all have an impact on ejector system performance. Refinery vacuum distillation towers use ejector systems to maintain tower top pressure and remove overhead gases. However, as with virtually all refinery equipment, performance may be affected by a number of variables. These variables may act independently or concurrently. It is important to understand basic operating principles of vacuum systems and how performance is affected by: utilities, corrosion and erosion, fouling, andmore » process conditions. Reputable vacuum-system suppliers have service engineers that will come to a refinery to survey the system and troubleshoot performance or offer suggestions for improvement. A skilled vacuum-system engineer may be needed to diagnose and remedy system problems. The affect of these variables on performance is discussed. A case history is described of a vacuum system on a crude tower in a South American refinery.« less

Life cycle analysis on fossil energy ratio of algal biodiesel: effects of nitrogen deficiency and oil extraction technology.

PubMed

Jian, Hou; Jing, Yang; Peidong, Zhang

2015-01-01

Life cycle assessment (LCA) has been widely used to analyze various pathways of biofuel preparation from "cradle to grave." Effects of nitrogen supply for algae cultivation and technology of algal oil extraction on life cycle fossil energy ratio of biodiesel are assessed in this study. Life cycle fossil energy ratio of Chlorella vulgaris based biodiesel is improved by growing algae under nitrogen-limited conditions, while the life cycle fossil energy ratio of biodiesel production from Phaeodactylum tricornutum grown with nitrogen deprivation decreases. Compared to extraction of oil from dried algae, extraction of lipid from wet algae with subcritical cosolvents achieves a 43.83% improvement in fossil energy ratio of algal biodiesel when oilcake drying is not considered. The outcome for sensitivity analysis indicates that the algal oil conversion rate and energy content of algae are found to have the greatest effects on the LCA results of algal biodiesel production, followed by utilization ratio of algal residue, energy demand for algae drying, capacity of water mixing, and productivity of algae.

Life Cycle Analysis on Fossil Energy Ratio of Algal Biodiesel: Effects of Nitrogen Deficiency and Oil Extraction Technology

PubMed Central

Jian, Hou; Jing, Yang; Peidong, Zhang

2015-01-01

Life cycle assessment (LCA) has been widely used to analyze various pathways of biofuel preparation from “cradle to grave.” Effects of nitrogen supply for algae cultivation and technology of algal oil extraction on life cycle fossil energy ratio of biodiesel are assessed in this study. Life cycle fossil energy ratio of Chlorella vulgaris based biodiesel is improved by growing algae under nitrogen-limited conditions, while the life cycle fossil energy ratio of biodiesel production from Phaeodactylum tricornutum grown with nitrogen deprivation decreases. Compared to extraction of oil from dried algae, extraction of lipid from wet algae with subcritical cosolvents achieves a 43.83% improvement in fossil energy ratio of algal biodiesel when oilcake drying is not considered. The outcome for sensitivity analysis indicates that the algal oil conversion rate and energy content of algae are found to have the greatest effects on the LCA results of algal biodiesel production, followed by utilization ratio of algal residue, energy demand for algae drying, capacity of water mixing, and productivity of algae. PMID:26000338

Territorial approach to increased energy consumption of water extraction from depletion of a highlands Mexican aquifer.

PubMed

Fonseca, Carlos Roberto; Esteller, María Vicenta; Díaz-Delgado, Carlos

2013-10-15

This work proposes a method to estimate increased energy consumption of pumping caused by a drawdown of groundwater level and the equivalent energy consumption of the motor-pump system in an aquifer under intensive exploitation. This method has been applied to the Valley of Toluca aquifer, located in the Mexican highlands, whose intensive exploitation is reflected in a decline in the groundwater level of between 0.10 and 1.6 m/year. Results provide a summary of energy consumption and a map of energy consumption isopleths showing the areas that are most susceptible to increases in energy consumption due to pumping. The proposed method can be used to estimate the effect of the intensive exploitation of the Valley of Toluca aquifer on the energy consumption of groundwater extraction. Finding reveals that, for the year 2006, groundwater extraction in the urban zone required 2.39 times more energy than the conditions observed 38 years earlier. In monetary terms, this reflects an increase of USD$ 3 million annually, according to 2005 energy production costs. Copyright © 2013 Elsevier Ltd. All rights reserved.

Vapor-barrier Vacuum Isolation System

NASA Technical Reports Server (NTRS)

Weinstein, Leonard M. (Inventor); Taminger, Karen M. (Inventor)

2014-01-01

A system includes a collimated beam source within a vacuum chamber, a condensable barrier gas, cooling material, a pump, and isolation chambers cooled by the cooling material to condense the barrier gas. Pressure levels of each isolation chamber are substantially greater than in the vacuum chamber. Coaxially-aligned orifices connect a working chamber, the isolation chambers, and the vacuum chamber. The pump evacuates uncondensed barrier gas. The barrier gas blocks entry of atmospheric vapor from the working chamber into the isolation chambers, and undergoes supersonic flow expansion upon entering each isolation chamber. A method includes connecting the isolation chambers to the vacuum chamber, directing vapor to a boundary with the working chamber, and supersonically expanding the vapor as it enters the isolation chambers via the orifices. The vapor condenses in each isolation chamber using the cooling material, and uncondensed vapor is pumped out of the isolation chambers via the pump.

Sensitivity of hot-cathode ionization vacuum gages in several gases

NASA Technical Reports Server (NTRS)

Holanda, R.

1972-01-01

Four hot-cathode ionization vacuum gages were calibrated in 12 gases. The relative sensitivities of these gages were compared to several gas properties. Ionization cross section was the physical property which correlated best with gage sensitivity. The effects of gage accelerating voltage and ionization-cross-section energy level were analyzed. Recommendations for predicting gage sensitivity according to gage type were made.

Successful Cleaning and Study of Contamination of Si(001) in Ultrahigh Vacuum

DOE Office of Scientific and Technical Information (OSTI.GOV)

Gheorghe, N. G.; Lungu, G. A.; Husanu, M. A.

2011-10-03

This paper presents the very first surface physics experiment performed in ultrahigh vacuum (UHV) in Romania, using a new molecular beam epitaxy (MBE) installation. Cleaning of a Si(001) wafer was achieved by using a very simple technique: sequences of annealing at 900-1000 deg. C in ultrahigh vacuum: low 10{sup -8} mbar, with a base pressure of 1.5x10{sup -10} mbar. The preparation procedure is quite reproducible and allows repeated cleaning of the Si(001) after contamination in ultrahigh vacuum. The Si(001) single crystal surface is characterized by low energy electron diffraction (LEED), reflection high energy electron diffraction (RHEED), and Auger electron spectroscopymore » (AES). The latter technique is utilized in order to investigate the sample contamination by the residual gas in the UHV chamber, as determined by a residual gas analyzer (RGA). Unambiguous assignment of oxidized and unoxidized silicon is provided; also, an important feature is that the LVV Auger peak at 90-92 eV cannot be solely attributed to clean Si (i.e. Si surrounded only by Si), but also to silicon atoms bounded with carbon. Even with a sum of partial pressures of oxygen and carbon containing molecules in the range of 5x10{sup -10} mbar, the sample is contaminated very quickly, having a (1/e) lifetime of about 76 minutes.« less

7 CFR 58.423 - Cheese vacuumizing chamber.

Code of Federal Regulations, 2010 CFR

2010-01-01

... 7 Agriculture 3 2010-01-01 2010-01-01 false Cheese vacuumizing chamber. 58.423 Section 58.423 Agriculture Regulations of the Department of Agriculture (Continued) AGRICULTURAL MARKETING SERVICE (Standards....423 Cheese vacuumizing chamber. The vacuum chamber shall be satisfactorily constructed and maintained...

7 CFR 58.423 - Cheese vacuumizing chamber.

Code of Federal Regulations, 2011 CFR

2011-01-01

... 7 Agriculture 3 2011-01-01 2011-01-01 false Cheese vacuumizing chamber. 58.423 Section 58.423 Agriculture Regulations of the Department of Agriculture (Continued) AGRICULTURAL MARKETING SERVICE (Standards....423 Cheese vacuumizing chamber. The vacuum chamber shall be satisfactorily constructed and maintained...

Effects of nanoscale vacuum gap on photon-enhanced thermionic emission devices

DOE Office of Scientific and Technical Information (OSTI.GOV)

Wang, Yuan; Liao, Tianjun; Zhang, Yanchao

2016-01-28

A new model of the photon-enhanced thermionic emission (PETE) device with a nanoscale vacuum gap is established by introducing the quantum tunneling effect and the image force correction. Analytic expressions for both the thermionic emission and tunneling currents are derived. The electron concentration and the temperature of the cathode are determined by the particle conservation and energy balance equations. The effects of the operating voltage on the maximum potential barrier, cathode temperature, electron concentration and equilibrium electron concentration of the conduction band, and efficiency of the PETE device are discussed in detail for different given values of the vacuum gapmore » length. The influence of the band gap of the cathode and flux concentration on the efficiency is further analyzed. The maximum efficiency of the PETE and the corresponding optimum values of the band gap and the operating voltage are determined. The results obtained here show that the efficiency of the PETE device can be significantly improved by employing a nanoscale vacuum gap.« less

Resolving the vacuum fluctuations of an optomechanical system using an artificial atom

NASA Astrophysics Data System (ADS)

Lecocq, F.; Teufel, J. D.; Aumentado, J.; Simmonds, R. W.

2015-08-01

Heisenberg’s uncertainty principle results in one of the strangest quantum behaviours: a mechanical oscillator can never truly be at rest. Even at a temperature of absolute zero, its position and momentum are still subject to quantum fluctuations. However, direct energy detection of the oscillator in its ground state makes it seem motionless, and in linear position measurements detector noise can masquerade as mechanical fluctuations. Thus, how can we resolve quantum fluctuations? Here, we parametrically couple a micromechanical oscillator to a microwave cavity to prepare the system in its quantum ground state and then amplify the remaining vacuum fluctuations into real energy quanta. We monitor the photon/phonon-number distributions using a superconducting qubit, allowing us to resolve the quantum vacuum fluctuations of the macroscopic oscillator’s motion. Our results further demonstrate the ability to control a long-lived mechanical oscillator using a non-Gaussian resource, directly enabling applications in quantum information processing and enhanced detection of displacement and forces.

Color Confinement and Screening in the θ Vacuum of QCD

DOE PAGES

Kharzeev, Dmitri E.; Levin, Eugene M.

2015-06-16

QCD perturbation theory ignores the compact nature of the SU(3) gauge group that gives rise to the periodic θ vacuum of the theory. In this paper, we propose to modify the gluon propagator to reconcile perturbation theory with the anomalous Ward identities for the topological current in the θ vacuum. As a result, the gluon couples to the Veneziano ghost describing the tunneling transitions between different Chern-Simons sectors of the vacuum; we call the emerging gluon dressed by ghost loops a “glost.” We evaluate the glost propagator and find that it has the form G(p)=(p 2+χ top/p 2) -1 wheremore » χ top is the Yang-Mills topological susceptibility related to the η" mass by the Witten-Veneziano relation; this propagator describes the confinement of gluons at distances ~χ top -1/4≃1 fm. The same functional form of the propagator was originally proposed by Gribov as a solution to the gauge copies problem that plagues perturbation theory. The resulting running coupling coincides with the perturbative one at p 2>>√χtop, but in the infrared region either freezes (in pure Yang-Mills theory) or vanishes (in full QCD with light quarks), in accord with experimental evidence. In conclusion, our scenario makes explicit the connection between confinement and topology of the QCD vacuum; we discuss the implications for spin physics, high energy scattering, and the physics of quark-gluon plasma.« less

Color Confinement and Screening in the θ Vacuum of QCD.

PubMed

Kharzeev, Dmitri E; Levin, Eugene M

2015-06-19

QCD perturbation theory ignores the compact nature of the SU(3) gauge group that gives rise to the periodic θ vacuum of the theory. We propose to modify the gluon propagator to reconcile perturbation theory with the anomalous Ward identities for the topological current in the θ vacuum. As a result, the gluon couples to the Veneziano ghost describing the tunneling transitions between different Chern-Simons sectors of the vacuum; we call the emerging gluon dressed by ghost loops a "glost." We evaluate the glost propagator and find that it has the form G(p)=(p(2)+χ(top)/p(2))(-1) where χ(top) is the Yang-Mills topological susceptibility related to the η' mass by the Witten-Veneziano relation; this propagator describes the confinement of gluons at distances ∼χ(top)(-1/4)≃1  fm. The same functional form of the propagator was originally proposed by Gribov as a solution to the gauge copies problem that plagues perturbation theory. The resulting running coupling coincides with the perturbative one at p(2)≫√[χ(top)], but in the infrared region either freezes (in pure Yang-Mills theory) or vanishes (in full QCD with light quarks), in accord with experimental evidence. Our scenario makes explicit the connection between confinement and topology of the QCD vacuum; we discuss the implications for spin physics, high energy scattering, and the physics of quark-gluon plasma.

Simulations of the HIE-ISOLDE radio frequency quadrupole cooler and buncher vacuum using the Monte Carlo test particle code Molflow+

NASA Astrophysics Data System (ADS)

Hermann, M.; Vandoni, G.; Kersevan, R.; Babcock, C.

2013-12-01

The existing ISOLDE radio frequency quadrupole cooler and buncher (RFQCB) will be upgraded in the framework of the HIE-ISOLDE design study. In order to improve beam properties, the upgrade includes vacuum optimization with the aim of tayloring the overall pressure profile: increasing gas pressure at the injection to enhance cooling and reducing it at the extraction to avoid emittance blow up while the beam is being bunched. This paper describes the vacuum modelling of the present RFQCB using Test Particle Monte Carlo (Molflow+). In order to benchmark the simulation results, real pressure profiles along the existing RFQCB are measured using variable helium flux in the cooling section and compared with the pressure profiles obtained with Molflow+. Vacuum conditions of the improved future RFQCB can then be simulated to validate its design.

Photo-generated carriers lose energy during extraction from polymer-fullerene solar cells

PubMed Central

Melianas, Armantas; Etzold, Fabian; Savenije, Tom J.; Laquai, Frédéric; Inganäs, Olle; Kemerink, Martijn

2015-01-01

In photovoltaic devices, the photo-generated charge carriers are typically assumed to be in thermal equilibrium with the lattice. In conventional materials, this assumption is experimentally justified as carrier thermalization completes before any significant carrier transport has occurred. Here, we demonstrate by unifying time-resolved optical and electrical experiments and Monte Carlo simulations over an exceptionally wide dynamic range that in the case of organic photovoltaic devices, this assumption is invalid. As the photo-generated carriers are transported to the electrodes, a substantial amount of their energy is lost by continuous thermalization in the disorder broadened density of states. Since thermalization occurs downward in energy, carrier motion is boosted by this process, leading to a time-dependent carrier mobility as confirmed by direct experiments. We identify the time and distance scales relevant for carrier extraction and show that the photo-generated carriers are extracted from the operating device before reaching thermal equilibrium. PMID:26537357

Engineering Matter Interactions Using Squeezed Vacuum

NASA Astrophysics Data System (ADS)

Zeytinoǧlu, Sina; Imamoǧlu, Ataç; Huber, Sebastian

2017-04-01

Virtually all interactions that are relevant for atomic and condensed matter physics are mediated by quantum fluctuations of the electromagnetic field vacuum. Consequently, controlling the vacuum fluctuations can be used to engineer the strength and the range of interactions. Recent experiments have used this premise to demonstrate novel quantum phases or entangling gates by embedding electric dipoles in photonic cavities or wave guides, which modify the electromagnetic fluctuations. Here, we show theoretically that the enhanced fluctuations in the antisqueezed quadrature of a squeezed vacuum state allow for engineering interactions between electric dipoles without the need for a photonic structure. Thus, the strength and range of the interactions can be engineered in a time-dependent way by changing the spatial profile of the squeezed vacuum in a traveling-wave geometry, which also allows the implementation of chiral dissipative interactions. Using experimentally realized squeezing parameters and including realistic losses, we predict single-atom cooperativities C of up to 10 for the squeezed-vacuum-enhanced interactions.

Lightweight Vacuum Jacket for Cryogenic Insulation. Volume 1

NASA Technical Reports Server (NTRS)

Barclay, D. L.; Bell, J. E.; Brogren, E. W.; Straayer, J. W.

1975-01-01

The feasibility of producing a lightweight vacuum jacket using state-of-the-art technology and materials was examined. Design and analytical studies were made on a full-scale, orbital maneuvering system fuel tank. Preliminary design details were made for the tank assembly, including an optimized vacuum jacket and multilayer insulation system. A half-scale LH2 test model was designed and fabricated, and a force/stiffness proof test was conducted on the vacuum jacket. A vacuum leak rate of .000001 atmosphere ml of helium per second was measured, approximately 1500 hours of vacuum pressure were sustained, and 29 vacuum-pressure cycles were experienced prior to failure.

Drying characteristics of whole Musa AA group ‘Kluai Leb Mu Nang’ using hot air and infrared vacuum

NASA Astrophysics Data System (ADS)

Kulketwong, C.; Thungsotanon, D.; Suwanpayak, N.

2017-06-01

Dried Musa AA group ‘Kluai Leb Mu Nang’ are the famous processing goods of Chumphon province, the south of Thailand. In this paper, we improved the qualities of whole Musa AA group ‘Kluai leb Mu Nang’ by using the hot air and infrared vacuum (HA and infrared vacuum) drying method which has two stages. The first stage of the method is the hot air (HA) and hot air-infrared (HAI) drying for rapidly reducing the moisture content and the drying times at atmospheric pressure, and the second stage, the moisture content, and color of the samples can be controlled by the HA and infrared vacuum drying. The experiment was evaluated by the terms of firmness, color change, moisture content, vacuum pressure and energy consumption at various temperatures. The results were found that the suitable temperature of the HAI and HA and infrared vacuum drying stages at 70°C and 55°C, respectively, while the suitable vacuum pressure in the second process was -0.4 bar. The samples were dried in a total of 28 hrs using 13.83 MJ/kg of specific energy consumption (stage 1 with 8.8 MJ/kg and stage 2 of 5.03 MJ/kg). The physical characteristics of the 21% (wb) of dried bananas can be measured the color change, L*=38.56, a*=16.47 and b*=16.3, was approximate the goods from the local market, whereas the firmness of them was more tender and shown a value of 849.56 kN/m3.

7 CFR 305.29 - Vacuum heat treatment schedule.

Code of Federal Regulations, 2010 CFR

2010-01-01

... 7 Agriculture 5 2010-01-01 2010-01-01 false Vacuum heat treatment schedule. 305.29 Section 305.29... SERVICE, DEPARTMENT OF AGRICULTURE PHYTOSANITARY TREATMENTS Heat Treatments § 305.29 Vacuum heat treatment... vacuum at 8 hours. Maintain the vacuum until the end of the treatment. Gradually increase the temperature...

Evaluation of a Prototype Hybrid Vacuum Pump to Provide Vacuum-Assisted Suspension for Above-Knee Prostheses

PubMed Central

Major, Matthew J.; Caldwell, Ryan; Fatone, Stefania

2015-01-01

Vacuum-assisted suspension (VAS) of prosthetic sockets utilizes a pump to evacuate air from between the prosthetic liner and socket, and are available as mechanical or electric systems. This technical note describes a hybrid pump that benefits from the advantages of mechanical and electric systems, and evaluates a prototype as proof-of-concept. Cyclical bench testing of the hybrid pump mechanical system was performed using a materials testing system to assess the relationship between compression cycles and vacuum pressure. Phase 1 in vivo testing of the hybrid pump was performed by an able-bodied individual using prosthesis simulator boots walking on a treadmill, and phase 2 involved an above-knee prosthesis user walking with the hybrid pump and a commercial electric pump for comparison. Bench testing of 300 compression cycles produced a maximum vacuum of 24 in-Hg. In vivo testing demonstrated that the hybrid pump continued to pull vacuum during walking, and as opposed to the commercial electric pump, did not require reactivation of the electric system during phase 2 testing. The novelty of the hybrid pump is that while the electric system provides rapid, initial vacuum suspension, the mechanical system provides continuous air evacuation while walking to maintain suspension without reactivation of the electric system, thereby allowing battery power to be reserved for monitoring vacuum levels. PMID:27462383

Extraction and preparation of high-aroma and low-caffeine instant green teas by the novel column chromatographic extraction method with gradient elution.

PubMed

Li, Qing-Rong; Wu, Min; Huang, Rui-Jie; Chen, Ya-Fei; Chen, Chan-Jian; Li, Hui; Ni, He; Li, Hai-Hang

2017-06-01

The lack of aroma and natural taste is a critical problem in production and consumption of instant green teas. A method to prepare instant green teas high in-natural-aroma and low-caffeine by the novel column chromatographic extraction with gradient elution is reported. This method simultaneously extracted aroma (or volatile) and non-aroma compounds from green tea. Green tea was loaded into columns with 2.0-fold of petroleum ether (PE): ethanol (8:2). After standing for 3 h until the aroma compounds dissolved, the column was sequentially eluted with 3.0-fold 40% ethanol and 3.5-fold water. The eluant was collected together and automatically separated into PE and ethanol aqueous phases. The aroma extracts was obtained by vacuum-evaporation of PE phase at 45 °C. The ethanol aqueous phase was vacuum-concentrated to aqueous and partially or fully decaffeinated with 4% or 9% charcoal at 70 °C. A regular instant green tea with epigallocatechin-3-gallate: caffeine of 3.5:1 and a low-caffeine instant green tea (less than 1% caffeine) with excellent aroma and taste were prepared, by combining the aroma and non-aroma extracts at a 1:10 ratio. This work provides a practical approach to solve the low-aroma and low-taste problems in the production of high quality instant green teas.

Gravitational baryogenesis in running vacuum models

NASA Astrophysics Data System (ADS)

Oikonomou, V. K.; Pan, Supriya; Nunes, Rafael C.

2017-08-01

We study the gravitational baryogenesis mechanism for generating baryon asymmetry in the context of running vacuum models. Regardless of whether these models can produce a viable cosmological evolution, we demonstrate that they produce a nonzero baryon-to-entropy ratio even if the universe is filled with conformal matter. This is a sound difference between the running vacuum gravitational baryogenesis and the Einstein-Hilbert one, since in the latter case, the predicted baryon-to-entropy ratio is zero. We consider two well known and most used running vacuum models and show that the resulting baryon-to-entropy ratio is compatible with the observational data. Moreover, we also show that the mechanism of gravitational baryogenesis may constrain the running vacuum models.

Enhanced yield of phenolic extracts from banana peels (Musa acuminata Colla AAA) and cinnamon barks (Cinnamomum varum) and their antioxidative potentials in fish oil.

PubMed

Anal, Anil Kumar; Jaisanti, Sirorat; Noomhorm, Athapol

2014-10-01

The bioactive compounds of banana peels and cinnamon barks were extracted by vacuum microwave and ultrasonic-assisted extraction methods at pre-determined temperatures and times. These methods enhance the yield extracts in shorter time. The highest yields of both extracts were obtained from the conditions which employed the highest temperature and the longest time. The extracts' yield from cinnamon bark method was higher by ultrasonic than vacuum microwave method, while vacuum microwave method gave higher extraction yield from banana peel than ultrasonic method. The phenolic contents of cinnamon bark and banana peel extracts were 467 and 35 mg gallic acid equivalent/g extract, respectively. The flavonoid content found in banana peel and cinnamon bark extracts were 196 and 428 mg/g quercetin equivalent, respectively. In addition, it was found that cinnamon bark gave higher 2,2-Diphenyl-1-1 picryhydrazyl (DPPH) radical scavenging activity and total antioxidant activity (TAA). The antioxidant activity of the extracts was analyzed by measuring the peroxide and p-anisidine values after oxidation of fish oils, stored for a month (30 days) at 25 °C and showed lesser peroxide and p-anisidine values in the fish oils containing the sample extracts in comparison to the fish oil without containing any extract. The banana peel and cinnamon extracts had shown the ability as antioxidants to prevent the oxidation of fish oil and might be considered as rich sources of natural antioxidant.

Recovery of materials from waste printed circuit boards by vacuum pyrolysis and vacuum centrifugal separation.

PubMed

Zhou, Yihui; Wu, Wenbiao; Qiu, Keqiang

2010-11-01

In this research, a two-step process consisting of vacuum pyrolysis and vacuum centrifugal separation was employed to treat waste printed circuit boards (WPCBs). Firstly, WPCBs were pyrolysed under vacuum condition at 600 °C for 30 min in a lab-scale reactor. Then, the obtained pyrolysis residue was heated under vacuum until the solder was melted, and then the molten solder was separated from the pyrolysis residue by the centrifugal force. The results of vacuum pyrolysis showed that the type-A of WPCBs (the base plates of which was made from cellulose paper reinforced phenolic resin) pyrolysed to form an average of 67.97 wt.% residue, 27.73 wt.% oil, and 4.30 wt.% gas; and pyrolysis of the type-B of WPCBs (the base plates of which was made from glass fiber reinforced epoxy resin) led to an average mass balance of 72.20 wt.% residue, 21.45 wt.% oil, and 6.35 wt.% gas. The results of vacuum centrifugal separation showed that the separation of solder was complete when the pyrolysis residue was heated at 400 °C, and the rotating drum was rotated at 1200 rpm for 10 min. The pyrolysis oil and gas can be used as fuel or chemical feedstock after treatment. The pyrolysis residue after solder separation contained various metals, glass fibers and other inorganic materials, which could be recycled for further processing. The recovered solder can be reused directly and it can also be a good resource of lead and tin for refining. Copyright © 2010 Elsevier Ltd. All rights reserved.

The influence of extraction procedure on ion concentrations in sediment pore water

USGS Publications Warehouse

Winger, P.V.; Lasier, P.J.; Jackson, B.P.

1998-01-01

Sediment pore water has the potential to yield important information on sediment quality, but the influence of isolation procedures on the chemistry and toxicity are not completely known and consensus on methods used for the isolation from sediment has not been reached. To provide additional insight into the influence of collection procedures on pore water chemistry, anion (filtered only) and cation concentrations were measured in filtered and unfiltered pore water isolated from four sediments using three different procedures: dialysis, centrifugation and vacuum. Peepers were constructed using 24-cell culture plates and cellulose membranes, and vacuum extractors consisted of fused-glass air stones attached with airline tubing to 60cc syringes. Centrifugation was accomplished at two speeds (2,500 and 10,000 x g) for 30 min in a refrigerated centrifuge maintained at 4?C. Only minor differences in chemical characteristics and cation and anion concentrations were found among the different collecting methods with differences being sediment specific. Filtering of the pore water did not appreciably reduce major cation concentrations, but trace metals (Cu and Pb) were markedly reduced. Although the extraction methods evaluated produced pore waters of similar chemistries, the vacuum extractor provided the following advantages over the other methods: (1) ease of extraction, (2) volumes of pore water isolated, (3) minimal preparation time and (4) least time required for extraction of pore water from multiple samples at one time.

Diffraction-limited storage-ring vacuum technology

PubMed Central

Al-Dmour, Eshraq; Ahlback, Jonny; Einfeld, Dieter; Tavares, Pedro Fernandes; Grabski, Marek

2014-01-01

Some of the characteristics of recent ultralow-emittance storage-ring designs and possibly future diffraction-limited storage rings are a compact lattice combined with small magnet apertures. Such requirements present a challenge for the design and performance of the vacuum system. The vacuum system should provide the required vacuum pressure for machine operation and be able to handle the heat load from synchrotron radiation. Small magnet apertures result in the conductance of the chamber being low, and lumped pumps are ineffective. One way to provide the required vacuum level is by distributed pumping, which can be realised by the use of a non-evaporable getter (NEG) coating of the chamber walls. It may not be possible to use crotch absorbers to absorb the heat from the synchrotron radiation because an antechamber is difficult to realise with such a compact lattice. To solve this, the chamber walls can work as distributed absorbers if they are made of a material with good thermal conductivity, and distributed cooling is used at the location where the synchrotron radiation hits the wall. The vacuum system of the 3 GeV storage ring of MAX IV is used as an example of possible solutions for vacuum technologies for diffraction-limited storage rings. PMID:25177979

Electric Propulsion Laboratory Vacuum Chamber

NASA Image and Video Library

1964-06-21

Engineer Paul Reader and his colleagues take environmental measurements during testing of a 20-inch diameter ion engine in a vacuum tank at the Electric Propulsion Laboratory (EPL). Researchers at the Lewis Research Center were investigating the use of a permanent-magnet circuit to create the magnetic field required power electron bombardment ion engines. Typical ion engines use a solenoid coil to create this magnetic field. It was thought that the substitution of a permanent magnet would create a comparable magnetic field with a lower weight. Testing of the magnet system in the EPL vacuum tanks revealed no significant operational problems. Reader found the weight of the two systems was similar, but that the thruster’s efficiency increased with the magnet. The EPL contained a series of large vacuum tanks that could be used to simulate conditions in space. Large vacuum pumps reduced the internal air pressure, and a refrigeration system created the cryogenic temperatures found in space.

Efficient Vacuum-Deposited Ternary Organic Solar Cells with Broad Absorption, Energy Transfer, and Enhanced Hole Mobility.

PubMed

Shim, Hyun-Sub; Moon, Chang-Ki; Kim, Jihun; Wang, Chun-Kai; Sim, Bomi; Lin, Francis; Wong, Ken-Tsung; Seo, Yongsok; Kim, Jang-Joo

2016-01-20

The use of multiple donors in an active layer is an effective way to boost the efficiency of organic solar cells by broadening their absorption window. Here, we report an efficient vacuum-deposited ternary organic photovoltaic (OPV) using two donors, 2-((2-(5-(4-(diphenylamino)phenyl)thieno[3,2-b]thiophen-2-yl)thiazol-5-yl)methylene)malononitrile (DTTz) for visible absorption and 2-((7-(5-(dip-tolylamino)thiophen-2-yl)benzo[c]-[1,2,5]thiadiazol-4-yl)methylene)malononitrile (DTDCTB) for near-infrared absorption, codeposited with C70 in the ternary layer. The ternary device achieved a power conversion efficiency of 8.02%, which is 23% higher than that of binary OPVs. This enhancement is the result of incorporating two donors with complementary absorption covering wavelengths of 350 to 900 nm with higher hole mobility in the ternary layer than that of binary layers consisting of one donor and C70, combined with energy transfer from the donor with lower hole mobility (DTTz) to that with higher mobility (DTDCTB). This structure fulfills all the requirements for efficient ternary OPVs.

Enhanced vacuum laser-impulse coupling by volume absorption at infrared wavelengths

NASA Astrophysics Data System (ADS)

Phipps, C. R., Jr.; Harrison, R. F.; Shimada, T.; York, G. W.; Turner, R. F.

1990-03-01

This paper reports measurements of vacuum laser impulse coupling coefficients as large as 90 dyne/W, obtained with single microsec-duration CO2 laser pulses incident on a volume-absorbing, cellulose-nitrate-based plastic. This result is the largest coupling coefficient yet reported at any wavelength for a simple, planar target in vacuum, and partly results from expenditure of internal chemical energy in this material. Enhanced coupling was also observed in several other target materials that are chemically passive, but absorb light in depth at 10- and 3-micron wavelengths. The physical distinctions are discussed between this important case and that of simple, planar surface absorbers (such as metals) which were studied in the same experimental series, in light of the predictions of a simple theoretical model.

Matter density perturbation and power spectrum in running vacuum model

NASA Astrophysics Data System (ADS)

Geng, Chao-Qiang; Lee, Chung-Chi

2017-01-01

We investigate the matter density perturbation δm and power spectrum P(k) in the running vacuum model, with the cosmological constant being a function of the Hubble parameter, given by Λ = Λ0 + 6σHH0 + 3νH2, in which the linear and quadratic terms of H would originate from the QCD vacuum condensation and cosmological renormalization group, respectively. Taking the dark energy perturbation into consideration, we derive the evolution equation for δm and find a specific scale dcr = 2π/kcr, which divides the evolution of the universe into the sub-interaction and super-interaction regimes, corresponding to k ≪ kcr and k ≫ kcr, respectively. For the former, the evolution of δm has the same behaviour as that in the Λ cold dark model, while for the latter, the growth of δm is frozen (greatly enhanced) when ν + σ > (<)0 due to the couplings between radiation, matter and dark energy. It is clear that the observational data rule out the cases with ν < 0 and ν + σ < 0, while the allowed window for the model parameters is extremely narrow with ν , |σ | ≲ O(10^{-7}).

Fretting Wear Damage Mechanism of Uranium under Various Atmosphere and Vacuum Conditions

PubMed Central

Li, Zhengyang; Wu, Yanping; Meng, Xiandong; Zhang, Dongxu

2018-01-01

A fretting wear experiment with uranium has been performed on a linear reciprocating tribometer with ball-on-disk contact. This study focused on the fretting behavior of the uranium under different atmospheres (Ar, Air (21% O2 + 78% N2), and O2) and vacuum conditions (1.05 and 1 × 10−4 Pa). Evolution of friction was assessed by coefficient of friction (COF) and friction-dissipated energy. The oxide of the wear surface was evaluated by Raman spectroscopy. The result shows that fretting wear behavior presents strong atmosphere and vacuum condition dependence. With increasing oxygen content, the COF decreases due to abrasive wear and formation of oxide film. The COF in the oxygen condition is at least 0.335, and it has a maximum wear volume of about 1.48 × 107 μm3. However, the COF in a high vacuum condition is maximum about 1.104, and the wear volume is 1.64 × 106 μm3. The COF in the low vacuum condition is very different: it firstly increased and then decreased rapidly to a steady value. It is caused by slight abrasive wear and the formation of tribofilm after thousands of cycles. PMID:29659484

Changes in CR-39 proton sensitivity due to prolonged exposure to high vacuums relevant to the National Ignition Facility and OMEGA.

PubMed

Manuel, M J-E; Rosenberg, M J; Sinenian, N; Rinderknecht, H; Zylstra, A B; Séguin, F H; Frenje, J; Li, C K; Petrasso, R D

2011-09-01

When used at facilities like OMEGA and the NIF, CR-39 is exposed to high vacuum environments before and after irradiation by charged particles and neutrons. Using an electrostatic linear accelerator at MIT, studies have been conducted to investigate the effects of high vacuum exposure on the sensitivity of CR-39 to fusion protons in the ~1-9 MeV energy range. High vacuum conditions, of order 10(-5) Torr, experienced by CR-39 samples at these facilities were emulated. It is shown that vacuum exposure times longer than ~16 h before proton irradiation result in a decrease in proton sensitivity, whereas no effect was observed for up to 67 h of vacuum exposure after proton irradiation. CR-39 sensitivity curves are presented for samples with prolonged exposure to high vacuum before and after proton irradiation. © 2011 American Institute of Physics

Orthogonal time-of-flight mass spectrometry of an ion beam with a broad kinetic energy profile.

PubMed

Miller, S W; Prince, B D; Bemish, R J

2017-10-01

A combined experimental and modeling effort is undertaken to assess a detection system composed of an orthogonal extraction time-of-flight (TOF) mass spectrometer coupled to a continuous ion source emitting an ion beam with kinetic energy of several hundred eV. The continuous ion source comprises an electrospray capillary system employing an undiluted ionic liquid emitting directly into vacuum. The resulting ion beam consists of ions with kinetic energy distributions of width greater than a hundred of eV and mass-to-charge (m/q) ratios ranging from 111 to 500 000 amu/q. In particular, the investigation aims to demonstrate the kinetic energy resolution along the ion beam axis (axial) of orthogonally extracted ions in measurements of the axial kinetic energy-specific mass spectrum, mass flow rate, and total ion current. The described instrument is capable of simultaneous measurement of a broad m/q range in a single acquisition cycle with approximately 25 eV/q axial kinetic energy resolution. Mass resolutions of ∼340 (M/ΔM, FWHM) were obtained for ions at m/q = 1974. Comparison of the orthogonally extracted TOF mass spectrum to mass flow and ion current measurements obtained with a quartz-crystal microbalance and Faraday cup, respectively, shows reasonable numeric agreement and qualitative agreement in the trend as a function of energy defect.

Vacuum energy density near static distorted black holes

DOE Office of Scientific and Technical Information (OSTI.GOV)

Frolov, V.P.; Sanchez, N.

1986-03-15

We investigate the contribution of massless fields of spins 0, 1/2, and 1 to the vacuum polarization near the event horizon of static Ricci-flat space-times. We do not assume any particular spatial symmetry. Within the Page-Brown ''ansatz'' we calculate /sup ren/ and /sup ren/ near static distorted black holes, for both the Hartle-Hawking (Vertical Bar>/sub H/) and Boulware (Vertical Bar>/sub B/) vacua. Using Israel's description of static space-times, we express these quantities in an invariant geometric way. We obtain that /sub H//sup ren/ and /sub H//sup ren/ near the horizon depend only on the two-dimensional geometry of the horizon surface.more » We find /sub H//sup ren/ = (1/48..pi../sup 2/ )K/sub 0/, /sub H//sup ren/ = (7..cap alpha..+12..beta.. )K/sub 0/ /sup 2/-..cap alpha../sup(/sup 2/)..delta..K/sub 0/. $K sub 0: is the Gaussian curvature of the horizon, and ..cap alpha.. and ..beta.. are numerical coefficients depending on the spin of a field. The term in /sup(/sup 2/)..delta..K/sub 0/ is characteristic of the distortion of the black hole. When the event horizon is not distorted, K/sub 0/ is a constant and this term disappears.« less

Error-based Extraction of States and Energy Landscapes from Experimental Single-Molecule Time-Series

NASA Astrophysics Data System (ADS)

Taylor, J. Nicholas; Li, Chun-Biu; Cooper, David R.; Landes, Christy F.; Komatsuzaki, Tamiki

2015-03-01

Characterization of states, the essential components of the underlying energy landscapes, is one of the most intriguing subjects in single-molecule (SM) experiments due to the existence of noise inherent to the measurements. Here we present a method to extract the underlying state sequences from experimental SM time-series. Taking into account empirical error and the finite sampling of the time-series, the method extracts a steady-state network which provides an approximation of the underlying effective free energy landscape. The core of the method is the application of rate-distortion theory from information theory, allowing the individual data points to be assigned to multiple states simultaneously. We demonstrate the method's proficiency in its application to simulated trajectories as well as to experimental SM fluorescence resonance energy transfer (FRET) trajectories obtained from isolated agonist binding domains of the AMPA receptor, an ionotropic glutamate receptor that is prevalent in the central nervous system.

21 CFR 884.5070 - Vacuum abortion system.

Code of Federal Regulations, 2010 CFR

2010-04-01

... 21 Food and Drugs 8 2010-04-01 2010-04-01 false Vacuum abortion system. 884.5070 Section 884.5070 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED... § 884.5070 Vacuum abortion system. (a) Identification. A vacuum abortion system is a device designed to...

46 CFR 153.368 - Pressure-vacuum valves.

Code of Federal Regulations, 2014 CFR

2014-10-01

... 46 Shipping 5 2014-10-01 2014-10-01 false Pressure-vacuum valves. 153.368 Section 153.368 Shipping... BULK LIQUID, LIQUEFIED GAS, OR COMPRESSED GAS HAZARDOUS MATERIALS Design and Equipment Cargo Venting Systems § 153.368 Pressure-vacuum valves. (a) The pressure side of a required pressure-vacuum relief valve...

46 CFR 153.368 - Pressure-vacuum valves.

Code of Federal Regulations, 2011 CFR

2011-10-01

... 46 Shipping 5 2011-10-01 2011-10-01 false Pressure-vacuum valves. 153.368 Section 153.368 Shipping... BULK LIQUID, LIQUEFIED GAS, OR COMPRESSED GAS HAZARDOUS MATERIALS Design and Equipment Cargo Venting Systems § 153.368 Pressure-vacuum valves. (a) The pressure side of a required pressure-vacuum relief valve...

46 CFR 153.368 - Pressure-vacuum valves.

Code of Federal Regulations, 2012 CFR

2012-10-01

... 46 Shipping 5 2012-10-01 2012-10-01 false Pressure-vacuum valves. 153.368 Section 153.368 Shipping... BULK LIQUID, LIQUEFIED GAS, OR COMPRESSED GAS HAZARDOUS MATERIALS Design and Equipment Cargo Venting Systems § 153.368 Pressure-vacuum valves. (a) The pressure side of a required pressure-vacuum relief valve...

46 CFR 153.368 - Pressure-vacuum valves.

Code of Federal Regulations, 2013 CFR

2013-10-01

... 46 Shipping 5 2013-10-01 2013-10-01 false Pressure-vacuum valves. 153.368 Section 153.368 Shipping... BULK LIQUID, LIQUEFIED GAS, OR COMPRESSED GAS HAZARDOUS MATERIALS Design and Equipment Cargo Venting Systems § 153.368 Pressure-vacuum valves. (a) The pressure side of a required pressure-vacuum relief valve...

46 CFR 153.368 - Pressure-vacuum valves.

Code of Federal Regulations, 2010 CFR

2010-10-01

... 46 Shipping 5 2010-10-01 2010-10-01 false Pressure-vacuum valves. 153.368 Section 153.368 Shipping... BULK LIQUID, LIQUEFIED GAS, OR COMPRESSED GAS HAZARDOUS MATERIALS Design and Equipment Cargo Venting Systems § 153.368 Pressure-vacuum valves. (a) The pressure side of a required pressure-vacuum relief valve...

21 CFR 884.5070 - Vacuum abortion system.

Code of Federal Regulations, 2013 CFR

2013-04-01

... 21 Food and Drugs 8 2013-04-01 2013-04-01 false Vacuum abortion system. 884.5070 Section 884.5070 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED... § 884.5070 Vacuum abortion system. (a) Identification. A vacuum abortion system is a device designed to...

21 CFR 884.5070 - Vacuum abortion system.

Code of Federal Regulations, 2014 CFR

2014-04-01

... 21 Food and Drugs 8 2014-04-01 2014-04-01 false Vacuum abortion system. 884.5070 Section 884.5070 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED... § 884.5070 Vacuum abortion system. (a) Identification. A vacuum abortion system is a device designed to...

21 CFR 884.5070 - Vacuum abortion system.

Code of Federal Regulations, 2012 CFR

2012-04-01

... 21 Food and Drugs 8 2012-04-01 2012-04-01 false Vacuum abortion system. 884.5070 Section 884.5070 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED... § 884.5070 Vacuum abortion system. (a) Identification. A vacuum abortion system is a device designed to...

21 CFR 884.5070 - Vacuum abortion system.

Code of Federal Regulations, 2011 CFR

2011-04-01

... 21 Food and Drugs 8 2011-04-01 2011-04-01 false Vacuum abortion system. 884.5070 Section 884.5070 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED... § 884.5070 Vacuum abortion system. (a) Identification. A vacuum abortion system is a device designed to...

Vacuum system for room temperature X-ray lithography source (XLS)

DOE Office of Scientific and Technical Information (OSTI.GOV)

Schuchman, J.C.

1988-09-30

A prototype room-temperature X-Ray Lithography Source (XLS)was proposed to be built at Brookhaven National Laboratory as part of a technology-transfer- to-American-industry program. The overall machine comprises a full energy linac, a 170 meter long transport line, and a 39 meter circumference storage ring. The scope of this paper will be limited to describing the storage ring vacuum system. (AIP)

Vacuum system for room temperature X-ray lithography source (XLS)

NASA Astrophysics Data System (ADS)

Schuchman, J. C.

1988-09-01

A prototype room-temperature X-Ray Lithography Source (XLS)was proposed to be built at Brookhaven National Laboratory as part of a technology-transfer- to-American-industry program. The overall machine comprises a full energy linac, a 170 meter long transport line, and a 39 meter circumference storage ring. The scope of this paper will be limited to describing the storage ring vacuum system. (AIP)

An energy ratio feature extraction method for optical fiber vibration signal

NASA Astrophysics Data System (ADS)

Sheng, Zhiyong; Zhang, Xinyan; Wang, Yanping; Hou, Weiming; Yang, Dan

2018-03-01

The intrusion events in the optical fiber pre-warning system (OFPS) are divided into two types which are harmful intrusion event and harmless interference event. At present, the signal feature extraction methods of these two types of events are usually designed from the view of the time domain. However, the differences of time-domain characteristics for different harmful intrusion events are not obvious, which cannot reflect the diversity of them in detail. We find that the spectrum distribution of different intrusion signals has obvious differences. For this reason, the intrusion signal is transformed into the frequency domain. In this paper, an energy ratio feature extraction method of harmful intrusion event is drawn on. Firstly, the intrusion signals are pre-processed and the power spectral density (PSD) is calculated. Then, the energy ratio of different frequency bands is calculated, and the corresponding feature vector of each type of intrusion event is further formed. The linear discriminant analysis (LDA) classifier is used to identify the harmful intrusion events in the paper. Experimental results show that the algorithm improves the recognition rate of the intrusion signal, and further verifies the feasibility and validity of the algorithm.

Vacuum casting of thick polymeric films

NASA Technical Reports Server (NTRS)

Cuddihy, E. F.; Moacanin, J.

1979-01-01

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

14 CFR 25.1433 - Vacuum systems.

Code of Federal Regulations, 2010 CFR

2010-01-01

... STANDARDS: TRANSPORT CATEGORY AIRPLANES Equipment Miscellaneous Equipment § 25.1433 Vacuum systems. There... discharge lines from the vacuum air pump when the delivery temperature of the air becomes unsafe. [Doc. No...

Ceramic vacuum tubes for geothermal well logging

DOE Office of Scientific and Technical Information (OSTI.GOV)

Kelly, R.D.

1977-01-12

The results of investigations carried out into the availability and suitability of ceramic vacuum tubes for the development of logging tools for geothermal wells are summarized. Design data acquired in the evaluation of ceramic vacuum tubes for the development of a 500/sup 0/C instrumentation amplifier are presented. The general requirements for ceramic vacuum tubes for application to the development of high temperature well logs are discussed. Commercially available tubes are described and future contract activities that specifically relate to ceramic vacuum tubes are detailed. Supplemental data is presented in the appendix. (MHR)

Fine tuning the ionic liquid-vacuum outer atomic surface using ion mixtures.

PubMed

Villar-Garcia, Ignacio J; Fearn, Sarah; Ismail, Nur L; McIntosh, Alastair J S; Lovelock, Kevin R J

2015-03-28

Ionic liquid-vacuum outer atomic surfaces can be created that are remarkably different from the bulk composition. In this communication we demonstrate, using low-energy ion scattering (LEIS), that for ionic liquid mixtures the outer atomic surface shows significantly more atoms from anions with weaker cation-anion interactions (and vice versa).

Vacuum ultraviolet photofragmentation of octadecane: photoionization mass spectrometric and theoretical investigation.

PubMed

Xu, Jing; Sang, Pengpeng; Zhao, Lianming; Guo, Wenyue; Qi, Fei; Xing, Wei; Yan, Zifeng

The photoionization and fragmentation of octadecane were investigated with infrared laser desorption/tunable synchrotron vacuum ultraviolet (VUV) photoionization mass spectrometry (IRLD/VUV PIMS) and theoretical calculations. Mass spectra of octadecane were measured at various photon energies. The fragment ions were gradually detected with the increase of photon energy. The main fragment ions were assigned to radical ions (C n H 2 n +1 + , n  = 4-11) and alkene ions (C n H 2 n + , n  = 5-10). The ionization energy of the precursor and appearance energy of ionic fragments were obtained by measuring the photoionization efficiency spectrum. Possible formation pathways of the fragment ions were discussed with the help of density functional theory calculations.

Vacuum chamber-free centrifuge with magnetic bearings.

PubMed

Park, Cheol Hoon; Kim, Soohyun; Kim, Kyung-Soo

2013-09-01

Centrifuges are devices that separate particles of different densities and sizes through the application of a centrifugal force. If a centrifuge could be operated under atmospheric conditions, all vacuum-related components such as the vacuum chamber, vacuum pump, diffusion pump, and sealing could be removed from a conventional centrifuge system. The design and manufacturing procedure for centrifuges could then be greatly simplified to facilitate the production of lightweight centrifuge systems of smaller volume. Furthermore, the maintenance costs incurred owing to wear and tear due to conventional ball bearings would be eliminated. In this study, we describe a novel vacuum chamber-free centrifuge supported by magnetic bearings. We demonstrate the feasibility of the vacuum chamber-free centrifuge by presenting experimental results that verify its high-speed support capability and motoring power capacity.

Vacuum deposition and curing of liquid monomers

DOEpatents

Affinito, J.D.

1993-11-09

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.

Vacuum deposition and curing of liquid monomers

DOEpatents

Affinito, J.D.

1995-03-07

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.

Vacuum deposition and curing of liquid monomers

DOEpatents

Affinito, John D.

1993-01-01

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.

Vacuum deposition and curing of liquid monomers

DOEpatents

Affinito, John D.

1995-01-01

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.

Cryogenic Insulation System for Soft Vacuum

NASA Technical Reports Server (NTRS)

Augustynowicz, S. D.; Fesmire, J. E.

1999-01-01

The development of a cryogenic insulation system for operation under soft vacuum is presented in this paper. Conventional insulation materials for cryogenic applications can be divided into three levels of thermal performance, in terms of apparent thermal conductivity [k-value in milliwatt per meter-kelvin (mW/m-K)]. System k-values below 0.1 can be achieved for multilayer insulation operating at a vacuum level below 1 x 10(exp -4) torr. For fiberglass or powder operating below 1 x 10(exp -3) torr, k-values of about 2 are obtained. For foam and other materials at ambient pressure, k-values around 30 are typical. New industry and aerospace applications require a versatile, robust, low-cost thermal insulation with performance in the intermediate range. The target for the new composite insulation system is a k-value below 4.8 mW/m-K (R-30) at a soft vacuum level (from 1 to 10 torr) and boundary temperatures of approximately 77 and 293 kelvin (K). Many combinations of radiation shields, spacers, and composite materials were tested from high vacuum to ambient pressure using cryostat boiloff methods. Significant improvement over conventional systems in the soft vacuum range was demonstrated. The new layered composite insulation system was also shown to provide key benefits for high vacuum applications as well.

Evolution of gettering technologies for vacuum tubes to getters for MEMS

NASA Astrophysics Data System (ADS)

Amiotti, M.

2008-05-01

Getter materials are technically proven and industrially accepted practical ways to maintain vacuum inside hermetically sealed tubes or devices to assure high reliability and long lifetime of the operating devices. The most industrially proven vacuum tube is the cathode rays tubes (CRTs), where large surfaces are available for the deposition of an evaporated barium film by a radio frequency inductive heating of a stainless steel container filled with a BaAl4 powder mixed to Ni powder. The evolution of the CRTs manufacturing technologies required also new types of barium getters able to withstand some thermal process in air without any deterioration of the evaporation characteristics. In other vacuum tubes such as traveling waves tubes, the space available for the evaporation of a barium film and the sorption capacity required to assure the vacuum for the lifetime of the devices did not allow the use of the barium film, prompting the development of sintered non evaporable getter pills that can be activated during the manufacturing process or by flowing current through an embedded resistance. The same sintered non evaporable getter pills could find usage also in evacuated parts to thermally isolate the infrared sensors for different final applications. In high energy physics particle accelerators, the getter technology moved from localized vacuum getter pumps or getter strips to a getter coating over the surface of vacuum chambers in order to guarantee a more uniform pumping speed. With the advent of solid state electronics, new challenges faced the getter technology to assure long life to vacuum or inert gas filled hermetical packages containing microelectronic devices, especially in the telecommunication and military applications. A well known problem of GaAs devices with Pd or Pt metalization is the H2 poisoning of the metal gate: to prevent this degradation a two layer getter film has been develop to absorb a large quantity of H2 per unit of getter surface. The

Vacuum-assisted venous return reduces blood usage.

PubMed

Banbury, Michael K; White, Jennifer A; Blackstone, Eugene H; Cosgrove, Delos M

2003-09-01

To determine whether vacuum-assisted venous return has clinical advantages over conventional gravity drainage apart from allowing the use of smaller cannulas and shorter tubing. A total of 150 valve operations were performed at our institution between February and July 1999 using vacuum-assisted venous return with small venous cannulas connected to short tubing. These were compared with (1) 83 valve operations performed between April 1997 and January 1998 using the initial version of vacuum-assisted venous return, and (2) 124 valve operations performed between January and April of 1997 using conventional gravity drainage. Priming volume, hematocrit value, red blood cell usage, and total blood product usage were compared multivariably. These comparisons were covariate and propensity adjusted for dissimilarities between the groups and confirmed by propensity-matched pairs analysis. Priming volume was 1.4 +/- 0.4 L for small-cannula vacuum-assisted venous return, 1.7 +/- 0.4 L for initial vacuum-assisted venous return, and 2.0 +/- 0.4 L for gravity drainage (P <.0001). Smaller priming resulted in higher hematocrit values both at the beginning of cardiopulmonary bypass (27% +/- 5% compared with 26% +/- 4% and 25% +/- 4%, respectively, P <.0001) and at the end (30% +/- 4% compared with 28% +/- 4% and 27% +/- 4%, respectively, P <.0001). Red cell transfusions were used in 17% of the patients having small-cannula vacuum-assisted venous return, 27% of the initial patients having vacuum-assisted venous return, and 37% of the patients having gravity drainage (P =.001); total blood product usage was 19%, 27%, and 39%, respectively (P =.002). Although ministernotomy also was associated with reduced blood product usage (P <.004), propensity matching on type of sternotomy confirmed the association of vacuum-assisted venous return with lowered blood product usage. Vacuum-assisted venous return results in (1) higher hematocrit values during cardiopulmonary bypass and (2) decreased

A modeling study of tidal energy extraction and the associated impact on tidal circulation in a multi-inlet bay system of Puget Sound

DOE PAGES

Wang, Taiping; Yang, Zhaoqing

2017-03-25

Previously, a major focus of tidal energy studies in Puget Sound were the deep channels such as Admiralty Inlet that have a larger power potential. Our paper focuses on the possibility of extracting tidal energy from minor tidal channels of Puget Sound by using a hydrodynamic model to quantify the power potential and the associated impact on tidal circulation. The study site is a multi-inlet bay system connected by two narrow inlets, Agate Pass and Rich Passage, to the Main Basin of Puget Sound. A three-dimensional hydrodynamic model was applied to the study site and validated for tidal elevations andmore » currents. Here, we examined three energy extraction scenarios in which turbines were deployed in each of the two passages and concurrently in both. Extracted power rates and associated changes in tidal elevation, current, tidal flux, and residence time were examined. Maximum instantaneous power rates reached 250 kW, 1550 kW, and 1800 kW, respectively, for the three energy extraction scenarios. Model results suggest that with the level of energy extraction in the three energy extraction scenarios, the impact on tidal circulation is very small. It is worth investigating the feasibility of harnessing tidal energy from minor tidal channels of Puget Sound.« less

A modeling study of tidal energy extraction and the associated impact on tidal circulation in a multi-inlet bay system of Puget Sound

DOE Office of Scientific and Technical Information (OSTI.GOV)

Wang, Taiping; Yang, Zhaoqing

Previously, a major focus of tidal energy studies in Puget Sound were the deep channels such as Admiralty Inlet that have a larger power potential. Our paper focuses on the possibility of extracting tidal energy from minor tidal channels of Puget Sound by using a hydrodynamic model to quantify the power potential and the associated impact on tidal circulation. The study site is a multi-inlet bay system connected by two narrow inlets, Agate Pass and Rich Passage, to the Main Basin of Puget Sound. A three-dimensional hydrodynamic model was applied to the study site and validated for tidal elevations andmore » currents. Here, we examined three energy extraction scenarios in which turbines were deployed in each of the two passages and concurrently in both. Extracted power rates and associated changes in tidal elevation, current, tidal flux, and residence time were examined. Maximum instantaneous power rates reached 250 kW, 1550 kW, and 1800 kW, respectively, for the three energy extraction scenarios. Model results suggest that with the level of energy extraction in the three energy extraction scenarios, the impact on tidal circulation is very small. It is worth investigating the feasibility of harnessing tidal energy from minor tidal channels of Puget Sound.« less

The emergence of gravity as a retro-causal post-inflation macro-quantum-coherent holographic vacuum Higgs-Goldstone field

NASA Astrophysics Data System (ADS)

Sarfatti, Jack; Levit, Creon

2009-06-01

We present a model for the origin of gravity, dark energy and dark matter: Dark energy and dark matter are residual pre-inflation false vacuum random zero point energy (w = - 1) of large-scale negative, and short-scale positive pressure, respectively, corresponding to the "zero point" (incoherent) component of a superfluid (supersolid) ground state. Gravity, in contrast, arises from the 2nd order topological defects in the post-inflation virtual "condensate" (coherent) component. We predict, as a consequence, that the LHC will never detect exotic real on-mass-shell particles that can explain dark matter ΩMDM approx 0.23. We also point out that the future holographic dark energy de Sitter horizon is a total absorber (in the sense of retro-causal Wheeler-Feynman action-at-a-distance electrodynamics) because it is an infinite redshift surface for static detectors. Therefore, the advanced Hawking-Unruh thermal radiation from the future de Sitter horizon is a candidate for the negative pressure dark vacuum energy.

Development of secondary chamber for tar cracking-improvement of wood pyrolysis performance in pre-vacuum chamber

NASA Astrophysics Data System (ADS)

Siahaan, S.; Homma, H.; Homma, H.

2018-02-01

Energy crisis and global warming, in other words, climate change are critical topics discussed in various parts of the world. Global warming primarily result from too much emission of carbon dioxide (CO2) in the atmosphere. To mitigate global warming, or climate change and improve electrification in rural areas, wood pyrolysis technology is developed in a laboratory scale, of which gases are directly applicable to the gas engine generator. Our laboratory has developed a prototype of wood pyrolysis plant with a pre-vacuum chamber. However, tar yield was around 40 wt% of feedstock. This research aims to reduce tar yield by secondary tar cracking. For the secondary tar cracking, a secondary pre-vacuum chamber is installed after primary pre-vacuum chamber. Gases generated in the primary pre-vacuum chamber are lead into the secondary chamber that is heated up to 1000 K. This paper reports performance of the secondary chamber for secondary tar cracking in homogeneous mode and heterogeneous mode with char.

Purifying Aluminum by Vacuum Distillation

NASA Technical Reports Server (NTRS)

Du Fresne, E. R.

1985-01-01

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

Impact of new physics on the EW vacuum stability in a curved spacetime background

NASA Astrophysics Data System (ADS)

Bentivegna, E.; Branchina, V.; Contino, F.; Zappalà, D.

2017-12-01

It has been recently shown that, contrary to an intuitive decoupling argument, the presence of new physics at very large energy scales (say around the Planck scale) can have a strong impact on the electroweak vacuum lifetime. In particular, the vacuum could be totally destabilized. This study was performed in a flat spacetime background, and it is important to extend the analysis to curved spacetime since these are Planckian-physics effects. It is generally expected that under these extreme conditions gravity should totally quench the formation of true vacuum bubbles, thus washing out the destabilizing effect of new physics. In this work we extend the analysis to curved spacetime and show that, although gravity pushes toward stabilization, the destabilizing effect of new physics is still (by far) the dominating one. In order to get model independent results, high energy new physics is parametrized in two different independent ways: as higher order operators in the Higgs field, or introducing new particles with very large masses. The destabilizing effect is observed in both cases, hinting at a general mechanism that does not depend on the parametrization details for new physics, thus maintaining the results obtained from the analysis performed in flat spacetime.

System for high throughput water extraction from soil material for stable isotope analysis of water

USDA-ARS?s Scientific Manuscript database

A major limitation in the use of stable isotope of water in ecological studies is the time that is required to extract water from soil and plant samples. Using vacuum distillation the extraction time can be less than one hour per sample. Therefore, assembling a distillation system that can process m...

Effects of Stream Turbine Array Configuration on Current Energy Extraction Near an Island

NASA Astrophysics Data System (ADS)

Chen, Y.; Lin, B.; Lin, J.

2014-12-01

Enhanced tidal currents close to an island appear to present the potential for power extraction. In this research, a three-dimensional numerical model is employed to predict the tidal current energy extraction potential from turbine arrays near an island. One of the significant challenges is to determine an optimal configuration of turbine array. This paper presents a detailed work to investigate the combined influences of topographic features and array configuration on the performance of power generation. Three single row arrays and three multiple-row arrays, with turbines being arranged in a staggered manner, are examined. It has been found that a single row array with a relatively small spacing between two turbines could achieve good efficiency due to the blockage effects, whereas a larger lateral spacing gives a better performance for multi-row arrays. The reason is that the bypass flow in a staggered layout would results in shadowing effect on downstream turbines. Model results also show that the wake influence can be minimized by increasing not only the longitudinal spacing, but also the lateral spacing. The tidal current flows are shown to have been affected by the inclusion of turbines, with less fluctuant wave in a tidal cycle. The extents of the observed impacts are not only within the turbine array field, but also moving around the island and propagating to the far-field. This study can be used to provide the reference information of the commercial-scale farms for tidal energy development. Keywords: Tidal currents; Array configuration; Energy extraction; Hydrodynamic process

Mikheyev-smirnov-wolfenstein effects in vacuum oscillations

PubMed

Friedland

2000-07-31

We point out that for solar neutrino oscillations with the mass-squared difference of Deltam(2) approximately 10(-10)-10(-9) eV(2), i.e., in the so-called vacuum oscillation range, the solar matter effects are non-negligible, particularly for the low energy pp neutrinos. One consequence of this is that the values of the mixing angle straight theta and pi/2-straight theta are not equivalent, making it necessary to consider the entire physical range of the mixing angle 0

Studies of Niobium Thin Film Produced by Energetic Vacuum Deposition

DOE Office of Scientific and Technical Information (OSTI.GOV)

Genfa Wu; Anne-Marie Valente; H. Phillips

2004-05-01

An energetic vacuum deposition system has been used to study deposition energy effects on the properties of niobium thin films on copper and sapphire substrates. The absence of working gas avoids the gaseous inclusions commonly seen with sputtering deposition. A biased substrate holder controls the deposition energy. Transition temperature and residual resistivity ratio of the niobium thin films at several deposition energies are obtained together with surface morphology and crystal orientation measurements by AFM inspection, XRD and TEM analysis. The results show that niobium thin films on sapphire substrate exhibit the best cryogenic properties at deposition energy around 123 eV.more » The TEM analysis revealed that epitaxial growth of film was evident when deposition energy reaches 163 eV for sapphire substrate. Similarly, niobium thin film on copper substrate shows that film grows more oriented with higher deposition energy and grain size reaches the scale of the film thickness at the deposition energy around 153 eV.« less

Breather cloth for vacuum curing

NASA Technical Reports Server (NTRS)

Reed, M. W.

1979-01-01

Finely-woven nylon cloth that has been treated with Teflon improves vacuum adhesive bonding of coatings to substrates. Cloth is placed over coating; entire assembly, including substrate, coating, and cloth, is placed in plastic vacuum bag for curing. Cloth allows coating to "breathe" when bag is evacuated. Applications include bonding film coatings to solar concentrators and collectors.

Vacuum Gas Tungsten Arc Welding

NASA Technical Reports Server (NTRS)

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

1997-01-01

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.

Lonely GPFUTV-the movement of water under the action of unknown vacuum

NASA Astrophysics Data System (ADS)

Lin, Weiyi

2013-11-01

In this paper, firstly, the experiment on the flow resistance of the aerated pipe flow is introduced. The experimental research on comparison between different volumes of air entrained is presented. Secondly, the characteristics of gravity pipe flow under the action of Torricelli's vacuum, shortly called as GPFUTV are dissertated, including creative and functional design, fundamental principle, etc. Under the joint action of an unknown vacuum energy and the formation of non-aerated flow the water flow is full-pipe and continuous, high-speed and non-rotational as distinguished from turbulent flow. Thirdly, an appeal in relation to the experimental research, the applied studies and basic theory research is given. For instance, experimental study of Torricelli's experiment phenomenon in the vacuum environment, applied study of the potential for GPFUTV to be developed for deep seawater suction technology and lifting technology for deep ocean mining, theoretical study of flow stability and flow resistance under GPFUTV condition, etc. At last, the famous GPFUTV project is illustrated. 12 years of rigorous and independent survey research.

Using Microwaves for Extracting Water from the Moon

NASA Technical Reports Server (NTRS)

Ethridge, Edwin C.; Kaukler, William; Hepburn, Frank

2009-01-01

This disk contains 2 videos that accompanies the talk. Twenty years ago, the Lunar Prospector remote sensing satellite provided evidence of relatively large hydrogen concentrations at the lunar poles and in particular concentrated in permanently shadowed craters. The scientific hypothesis is that the hydrogen is in the form of cryo-trapped water just under the surface of the soil. If true this would mean that an average of about 2% water ice is mixed with the lunar soil existing in the form of ice at cryogenic temperatures. For 5 years we have been investigating the use of microwaves for the processing of lunar soil. One of the early uses could be to use microwave energy to extract volatiles and in particular water from the lunar permafrost. Prototype experiments have shown that microwave energy at 2.45 GHz, as in consumer microwave ovens, will couple with and heat cryogenically cooled lunar soil permafrost simulant, resulting in the rapid sublimation of water vapor into the vacuum chamber. The water vapor has been collected on a cryogenic cold trap with high efficiency. The primary advantage of microwave processing is that the volatiles can be extracted in situ. Excavation would not be required. Microwave frequency dielectric property measurements are being made of different lunar soil simulants and plans are to measure Apollo lunar soil at different frequencies and over a range of temperatures. The materials properties are being used to evaluate the heating of lunar soil and develop COMSOL models that can be used to evaluate different microwave extraction scenarios. With COMSOL the heating from cryogenic temperatures can be calculated and COMSOL will permit temperature dependent materials properties to be used during the heating process. Calculations at different microwave frequencies will allow the evaluation of the type of hardware that would be needed to most efficiently extract the water and other volatiles. The 1st video shows the results of the COMSOL

Using Microwaves for Extracting Water from the Moon

NASA Technical Reports Server (NTRS)

Ethridge, Edwin C.; Kaukler, William; Hepburn, Frank

2009-01-01

This disk contains a video that accompanies the talk. Twenty years ago, the Lunar Prospector remote sensing satellite provided evidence of relatively large hydrogen concentrations at the lunar poles and in particular concentrated in permanently shadowed craters. The scientific hypothesis is that the hydrogen is in the form of cryo-trapped water just under the surface of the soil. If true this would mean that an average of about 2% water ice is mixed with the lunar soil existing in the form of ice at cryogenic temperatures. For 5 years we have been investigating the use of microwaves for the processing of lunar soil. One of the early uses could be to use microwave energy to extract volatiles and in particular water from the lunar permafrost. Prototype experiments have shown that microwave energy at 2.45 GHz, as in consumer microwave ovens, will couple with and heat cryogenically cooled lunar soil permafrost simulant, resulting in the rapid sublimation of water vapor into the vacuum chamber. The water vapor has been collected on a cryogenic cold trap with high efficiency. The primary advantage of microwave processing is that the volatiles can be extracted in situ. Excavation would not be required. Microwave frequency dielectric property measurements are being made of different lunar soil simulants and plans are to measure Apollo lunar soil at different frequencies and over a range of temperatures. The materials properties are being used to evaluate the heating of lunar soil and develop COMSOL models that can be used to evaluate different microwave extraction scenarios. With COMSOL the heating from cryogenic temperatures can be calculated and COMSOL will permit temperature dependent materials properties to be used during the heating process. Calculations at different microwave frequencies will allow the evaluation of the type of hardware that would be needed to most efficiently extract the water and other volatiles. The video shows the partial results of the COMSOL

Apparatus For Metal/Inert-Gas Welding In Vacuum

NASA Technical Reports Server (NTRS)

Stocks, C. O.

1994-01-01

Metal/inert-gas welding-torch assembly operates in vacuum. Plasma generated in interior chamber and focused onto workpiece in vacuum. Pinch rollers feed wire to weld puddle. Controlled flow of plasma reduces dispersal in vacuum, preventing extinction.

Kinetic modeling of ultrasound-assisted extraction of phenolic compounds from grape marc: influence of acoustic energy density and temperature.