Pumping speed of parallel-louvre-blind-type cryopumps

International Nuclear Information System (INIS)

Saho, Norihide; Ogata, Hisanao; Kunugi, Yosifumi; Uede, Taisei; Yamasita, Yasuo; Kawakami, Hiroyuki.

1993-01-01

As a new type of actual-sized cryopump with high pumping speed, a parallel-louvre-blind type cryopump of a rectangular cross section with opening distance B, width C and depth D, is proposed and is produced as a trial pump unit designed as actual size. The influence of pump depth size ratio R d (=D/B) and number of secondary cryopanels on the transmission probability P bc of the pump unit is calculated by Monte Carlo simulation, and the hydrogen pumping speed is measured by experiments. The following results are obtained. (1) The transmission probability of a cryopump designed with dimensional ratio of R d = 1.3 is calculated to be 0.66 at ratios of R c (=B/C) = 0.88, which means that hydrogen pumping speed of cryopumps of this size can attain 294 m 3 · s -1 /m 2 per opening area. (2) The real hydrogen pumping speed of the trial pump unit with 30 secondary cryopanels is measured as 295 m 3 · s -1 /m 2 . (author)

Commissioning result of the KSTAR in-vessel cryo-pump

Energy Technology Data Exchange (ETDEWEB)

Chang, Y. B.; Lee, H. J.; Park, Y.M. [National Fusion Research Institute, Daejeon (Korea, Republic of); and others

2013-12-15

KSTAR in-vessel cryo-pump has been installed in the vacuum vessel top and bottom side with up-down symmetry for the better plasma density control in the D-shape H-mode. The cryogenic helium lines of the in-vessel cryo-pump are located at the vertical positions from the vacuum vessel torus center 2,000 mm. The inductive electrical potential has been optimized to reduce risk of electrical breakdown during plasma disruption. In-vessel cryo-pump consists of three parts of coaxial circular shape components; cryo-panel, thermal shield and particle shield. The cryo-panel is cooled down to below 4.5 K. The cryo-panel and thermal shields were made by Inconel 625 tube for higher mechanical strength. The thermal shields and their cooling tubes were annealed in air environment to improve the thermal radiation emissivity on the surface. Surface of cryo-panel was electro-polished to minimize the thermal radiation heat load. The in-vessel cryo-pump was pre-assembled on a test bed in 180 degree segment base. The leak test was carried out after the thermal shock between room temperature to LN2 one before installing them into vacuum vessel. Two segments were welded together in the vacuum vessel and final leak test was performed after the thermal shock. Commissioning of the in-vessel cryo-pump was carried out using a temporary liquid helium supply system.

On the energy consumption of cryogenic systems and the choice of cryopumps

International Nuclear Information System (INIS)

Kholod, Yu.V.; Yuferov, V.B.

1981-01-01

Energy consumption during the mutual use of cryogenic magnetic and vacuum systems including superconductina magnet, forevacuum and high vacuum cryopumps, is analyzed. The portion of energy consumption on preliminary condensational pumping-out of vaccuum chamber with volume of 6 m 3 for the considered case does not exceed 12% and decreases in time. Summary portion of energy consumption on operation of forevacuum and high vacuum cryopumps does not exceed one third of energy consumption on preliminary cooling of superconducting magnet and decreases to 10% during stationary operation of cryogenic system during 85O hours. A comparison of general and specific energy consumptions during the operation of different condensational cryopumps as well as of forevacuum condensational and sorption pumps is made. A conclusion is made that at small periods of time (tens of hours) of cryovacuum system operation it is expidient to use one cryopump with a wide range of working pressures (atmosphere-superhigh vacuum) instead of a combination of forevacuum and high vacuum cryopumps. Besides, a conclusion is made on expediency of the use of nitrogen condensational pumps instead of nitrogen cryosorption ones in the range of high pressures (760-10 mm Hg) expecially during the pumping out of vacuum chambers of high volume (1m 3 and higher). It is shown that account of energy consumptions on preliminary cooling of cryopumps and high vacuum ones in particular, at small (tens of hours) times of their operation increases average specific energy consumptions about 3 times. It is concluded that one can disregard the energy consumption used for preliminary cooling of cryopumps only in case of their stationary operation during about 10 3 hours [ru

The suspension (Frost) suture: experience and applications.

Science.gov (United States)

Connolly, Karen L; Albertini, John G; Miller, Christopher J; Ozog, David M

2015-03-01

The Frost suture is a well-known surgical technique for providing upward tension on the lower lid to prevent or correct ectropion after surgical interventions in the periorbital area. Despite its relatively common use, comprehensive information on executing this technique is not readily available. To review eyelid anatomy, indications, and proper technique for performing the Frost suture, as well as potential complications. A review of the literature on Frost sutures was performed. Cadaveric dissection was performed to demonstrate placement of the Frost suture. The Frost suture is a useful method to reduce the risk of ectropion after surgery near the lower eyelid. Downward pull on the lid can occur with normal wound contracture even if ectropion is not present with the initial repair, reinforcing the need for preventive measures. Potential complications of this technique include superficial skin erosion of the upper lid, corneal abrasion, and blockage of the field of vision while the suture is in place.

Investigation into the pumping characteristics of ITER cryopumps

International Nuclear Information System (INIS)

Day, C.; Mack, A.

1998-01-01

Within the framework of the European fusion technology programme, a cryopump system for ITER is being developed. It is based on combined sorption and condensation of gases at SK-surfaces, which are coated with activated charcoal. For verification of the design conditions an experimental programme has been launched. The tested cryopanels followed a quilted design, which is currently being discussed for its use in ITER. According to the composition range of the ITER exhaust gas in the various operation modes foreseen, pure gases (protium, deuterium, helium and neon) and gas mixtures (pseudobinaries of a D 2 -based mixture and one noble gas out of helium, neon or argon) were investigated. Quantitative measurements of pumping speed and equilibrium pressures at zero flow conditions were performed as a function of gas load; relative pumping probabilities were also derived. It is revealed that protium is pumped by sorption whereas neon is pumped by sublimation and deuterium is subjected to both mechanisms. The results demonstrate that the required pump ultimate pressure can be achieved. It is further shown that for the gases investigated the pumping characteristics will not be a limiting factor; the ITER requirements are well achieved. The saturation capacity will not be reached, except if pure helium is pumped. (orig.)

Explosion potential of neutral-beam source cryopumps for TFTR

International Nuclear Information System (INIS)

Graham, W.G.; Lim, T.H.; Ruby, L.

1977-12-01

The explosion potential of the test cryopump became a paramount issue in the safety analysis required for the reactor experiment. The administrative limit for loading of the cryopump with normal hydrogen or deuterium is that amount of gas which will produce a partial pressure of 13 torr at a total pressure of 1 atmosphere, i.e., a 1.7% mixture by volume. At atmospheric pressure, combustion can occur for mixtures in the range 4.0 to 75%. It is important to know whether, in a leak-up-to-air accident, when the partial pressure will range from 100% to 1.7%, an explosion can occur. For the test cryopump (250l), loaded to the administrative limit, the energy of combustion would amount to 9.21 x 10 5 J, or 21.9 g of T.N.T. equivalent. However, for a TFTR beamline (73,000l), the corresponding numbers are 2.69 x 10 7 J, or 6.39 x 10 3 g of T.N.T. equivalent

Study on atmospheric hydrogen enrichment by cryopump method and isotope separation by gas chromatography

International Nuclear Information System (INIS)

Taniyama, Yuki; Momoshima, Noriyuki

2001-01-01

To obtain the information of source of atmospheric hydrogen tritium an analysis of tritium isotopes is thought to be effective. So an atmospheric hydrogen enrichment apparatus and a cryogenic gas chromatographic column were made. Experiments were carried out to study the performance of cryopump to enrich atmospheric hydrogen and the column to separate hydrogen isotopes that obtained by cryopump method. The cryopump was able to process about 1000 1 atmosphere and the column was able to separate hydrogen isotopes with good resolution. (author)

Integration of cryopump instrumentation for SST-1 NBI

International Nuclear Information System (INIS)

Bansal, Laxmi Kant; Patel, Paresh J.; Prahlad, V.

2015-01-01

A positive ion neutral injector (PINI) capable in delivering 5MW (55kV, 90A) ion beam power is being operated for SST-1 neutral beam injection (NBI). The production and neutralization of the ion beams in the injector requires a gas throughput of 20 torr I/s in the plasma box and 50-100 torr I/s in the neutralizer section. It is necessary to maintain operating pressure of vessel at 10 -5 torr to reduce the re-ionization loss of beam within tolerable limits. Conventional Turbo molecular pumps cannot maintain this vacuum level at required gas feed rate so two cryo condensation pumps are being operated to achieve require vacuum in vessel. In order to monitor and optimize the performance of cryopumps, it is necessary to measure the temperature at various locations in LN 2 and LHe path. It is also required to monitor the level of LHe and LN 2 in cryopumps. Several temperature and level sensors are mounted at various places in cryopumps and integrated with PLC and SCADA based control system. This paper presents the details of sensor mounting, signals conditioning, scheme of their integration with PLC and SCADA and results in detail. (author)

Argon Kα measurement on DIII endash D by Ross filters technique (abstract)

International Nuclear Information System (INIS)

Snider, R.T.; Bogatu, I.N.; Brooks, N.H.; Wade, M.R.

1999-01-01

Techniques to reduce the heat flux to the divertor plates in tokamak power plants and the consequent erosion of, and subsequent damage to the divertor target plates include the injection of impurities such as argon, that can dissipate the energy (through radiative or collisional processes) before it reaches the target plates. An important issue with this type of scheme is poisoning of the plasma core by the impurities introduced in the divertor region. Subsequently, there is a desire to measure the profiles of the injected impurities in the core. X-ray Ross filters with an effective narrow band pass centered on the argon Kα line at 3.2 keV, have been installed on two of the existing x-ray arrays on DIII endash D in order to help determine the argon concentration profiles. Emissivity profiles of the Kα lines and the emissivity profiles for the argon enhanced continuum can be inferred from the inverted filtered x-ray brightness signals if T e , n e , and Ar 18+ profiles are known. The MIST code is used to couple the filtered x-ray signals to the time dependent measurements of T e and n e . Further, the Ar 16+ profiles measured by charge transfer spectroscopy, are used as a constraint on the MIST code runs to calculate Ar 18+ profiles and unfold the argon emissivity profiles. A discussion of the Ross filters, the DIII endash D argon data, and the data analysis scheme for inferring argon emissivity profiles will be discussed. Estimates of the total argon concentration in the core determined from this technique in DIII endash D argon puff experiments will be presented. copyright 1999 American Institute of Physics

Design and Analysis of the Cryopump for the DIII-D Upper Divertor

International Nuclear Information System (INIS)

Reis, E.E.; Baxi, C.B.; Bozek, A.S.

1999-01-01

A cryocondensation pump for the upper inboard divertor on DIII-D is to be installed in the vacuum vessel in the fall of 1999. The cryopump removes neutral gas particles from the divertor and prevents recycling to the plasma. This pump is designed for a pumping speed of 18,000 ell/s at 0.4 mTorr. The cryopump is toroidally continuous to minimize inductive voltages and avoid electrical breakdown during disruptions. The cryopump consists of a 25 mm Inconel tube cooled by liquid helium and is surrounded by nitrogen cooled shields. A segmented ambient temperature radiation/particle shield protects the nitrogen shields. The pump is subjected to a steady state heat load of less than 10 W due to conduction and radiation heat transfer. The helium tube will be subjected to Joule heating of less than 300 J due to induced current and a particle load of less than 12 W during plasma operation. The thermal design of the cryopump requires that it be cooled by 5 g/s liquid helium at an inlet pressure of 115 kPa and a temperature of 4.35 K. Thermal analysis and tests show that the helium tube can absorb a transient heat load of up to 100 W for 10 s and still pump deuterium at 6.3 K. Disruptions induce toroidal currents in the helium line and nitrogen shields. These currents cross the rapidly changing magnetic fields, applying complex dynamic loads on the cryopump. The forces on the pump are extrapolated from magnetic measurements from DIII-D plasma disruptions and scaled to a 3 MA disruption. The supports for the nitrogen shield consist of a racetrack design, which are stiff for reacting the disruption loads, but are radially flexible to allow differential thermal displacements with the vacuum vessel. Static and dynamic finite element analyses of the cryopump show that the stresses and displacements over a range of disruption and thermal loadings are acceptable

Cryopump measurements relating to safety, pumping speed, and radiation outgassing

International Nuclear Information System (INIS)

Graham, W.G.; Ruby, L.

1978-09-01

A test cryopump has been constructed to investigate operation in close proximity to a neutral beam, to determine static and dynamic pumping speeds, and to study outgassing such as might be produced by a pulse of nuclear radiation. No difficulty was encountered in operating the cryopump close to a deuterium neutral-beam source suitable for a fusion-reactor injector. Static and dynamic pumping-speed measurements agreed well, but were somewhat lower than expectations, probably due to the unusual method chosen to supply liquid helium. Safety tests showed that hydrogen could not be ignited at any subatmospheric pressure resulting from a leak-up-to-air accident. The possible hazard of liquid-oxygen condensation in such accidents was not explored. Tests made with pulses of neutrons and gamma rays produced by a TRIGA showed that the cryopump could be partially outgassed by radiation pulses of sufficient intensity. However, the effect is ascribed to the gamma-ray component of the TRIGA pulse which is about 10 3 times that expected from a fusion reactor such as TFTR

Subcuticular Suture Technique: Alternative to Frost Suture to Prevent Ectropion After Transcutaneous Incision of Lower Eyelid.

Science.gov (United States)

Kudva, Adarsh; Kamath, Abhay; Cariappa, K M; Gadicherla, Srikanth; Dhara, B Vasantha

2017-12-01

An ectropion is a complication that can arise from reconstruction in the infraorbital region. Often, this complication occurs despite proper positioning of the lower lid at the time of closure. Various transcutaneous approaches to orbit skeleton have investigated in view of complication arising from them. A subtarsal approach with a postoperative Frost suture gives an advantage to reduce the occurrence of ectropion especially after treatment of orbital floor fractures. This case describes a method of subcuticular suturing technique for subtarsal incision of lower lid which can be used to support the lid during healing period, thus decreasing the rate of ectropion. The technique described here is an alterative method for frost suturing with certain advantages.

Full-scale chilled pipeline frost heave testing, Fairbanks, Alaska, USA

Energy Technology Data Exchange (ETDEWEB)

Hazen, B. [Northern Engineering and Scientific, Anchorage, AK (United States); Isaacs, R.M. [RMI Associates, Camano Island, WA (United States); Myrick, J.E. [Myrick International, Tyler, TX (United States)

2010-07-01

This paper discussed a chilled pipeline frost-heave testing facility that was developed to simulate and record the rate of frost heave and frost-bulb growth for a buried, chilled pipeline in frost-susceptible soil and to determine the effectiveness of different mitigation techniques. The test facility, which was established near Fairbanks, Alaska, in 1979, has 10 test sections using 1.22-metre-diameter pipe. The testing involved un-insulated, insulated, and insulated with over-excavation and gravel berm configurations as well as the frost heave of the chilled pipeline. The test facility was described in detail. Frost heave and frost-bulb growth measurements from the first 10 months of testing were presented, as these are the first data to enter the public domain. The testing was undertaken to investigate the frost-heave relationships between sections, to better understand frost heave in permafrost, to explore possible mitigation options, and to advance the predicative capabilities of frost heave models. 12 refs., 1 tab., 17 figs.

Continuous cryopump for steady state mirror fusion reactors

International Nuclear Information System (INIS)

Batzer, T.H.; Call, W.R.

1983-01-01

The characteristics of mirror fusion reactors, i.e., steady state operation, a low neutral gas density, and a large gas throughput require unique vacuum pumping capabilities. One approach that appears to meet these requirements is a liquid helium-cooled cryopump system in which a fixed portion can be isolated and degassed while the remainder continues to pump. The time to degas a rotating, fixed portion of the pumping area and the ratio of that area to the total area fixes the gas inventory in the chamber. It follows that the active pump area maintains the required neutral gas density and the time-averaged degassing rate equals the gas throughput. We have built such a cryopump whereby the gas condensed (deuterium) on the liquid helium-cooled panel can be transferred to a collector pump and subsequently to an exterior mechanical pump and exhausted. At panel loadings as high as 0.55 Torr-/lcm 2 the gas leakage during degassing is less than 8% and the degassing time is less than 10 min. Scaling to reactor size appears to be feasible

Measurements of seasonal frost depth by frost tube in Japan

Science.gov (United States)

Harada, K.; Yoshikawa, K.; Iwahana, G.; Stanilovskaya, J. V.; Sawada, Y.; Sone, T.

2017-12-01

Since 2011 winter season, frost depths have been measured as an outreach program in Hokkaido, northern part of Japan, where seasonal ground freezing occurs in winter. Frost depths were measured in elementary, junior high and high schools in order to emphasis their interest for earth sciences. At schools, using simple frost tube, measurements were conducted directly once a week by students or teacher during ground freezing under no snow-removal condition. A lecture was made in class and a frost tube was set at schoolyard, as the same tube and protocol as UAF's Permafrost Outreach Program, using clear tube with blue-colored water. In 2011 winter season, we started measurements at three schools, and the number of school extended to 32 in 2016 season, 26 elementary schools, 5 junior high schools and one high school. We visited schools in summer time or just before frost season to talk about the method of measurement, and measurements by students started just after ground freezing. After the end of frozen period, we visited schools again to explain results of each school or another schools in Japan, Alaska, Canada or Russia. The measured frost depths in Hokkaido ranged widely, from only a few centimeter to more than 50 cm. However, some schools had no frost depth due to heavy snow. We confirmed that the frost depth strongly depends on air temperature and snow depth. The lecture was made to student why the frost depth ranged widely, and the effect of snow was explained by using the example of igloo. In order to validate the effect of snow and to compare frost depths, we tried to measure frost depths under snow-removal and no snow-removal conditions at the same elementary school. At the end of December, depths had no significant difference between these conditions, and the difference went to 14 cm after one month, with about 30 cm of snow depth. After these measurements and lectures, students noticed snow has a role as insulator and affects the frost depth.

Frost induced damages within porous materials - from concrete technology to fuel cells technique

Science.gov (United States)

Palecki, Susanne; Gorelkov, Stanislav; Wartmann, Jens; Heinzel, Angelika

2017-12-01

Porous media like concrete or layers of membrane electrode assemblies (MEA) within fuel cells are affected by a cyclic frost exposure due to different damage mechanisms which could lead to essential degradation of the material. In general, frost damages can only occur in case of a specific material moisture content. In fuel cells, residual water is generally available after shut down inside the membrane i.e. the gas diffusion layer (GDL). During subsequent freezing, this could cause various damage phenomena such as frost heaves and delamination effects of the membrane electrode assembly, which depends on the location of pore water and on the pore structure itself. Porous materials possess a pore structure that could range over several orders of magnitudes with different properties and freezing behaviour of the pore water. Latter can be divided into macroscopic, structured and pre-structured water, influenced by surface interactions. Therefore below 0 °C different water modifications can coexist in a wide temperature range, so that during frost exposure a high amount of unfrozen and moveable water inside the pore system is still available. This induces transport mechanisms and shrinkage effects. The physical basics are similar for porous media. While the freezing behaviour of concrete has been studied over decades of years, in order to enhance the durability, the know-how about the influence of a frost attack on fuel cell systems is not fully understood to date. On the basis of frost damage models for concrete structures, an approach to describe the impact of cyclic freezing and thawing on membrane electrode assemblies has been developed within this research work. Major aim is beyond a better understanding of the frost induced mechanisms, the standardization of a suitable test procedure for the assessment of different MEA materials under such kind of attack. Within this contribution first results will be introduced.

Robert Frost on Writing.

Science.gov (United States)

Barry, Elaine

This book is a collection of Frost's letters, reviews, introductions, lectures, and interviews on writing dating back to 1913. It provides Frost's view of literature, and its relation to language and social order. Part one, "Frost as a Literary Critic," discusses the scope of Frost's criticism and Frost as both critical theorist and…

Study of Hydrogen Pumping through Condensed Argon in Cryogenic pump

International Nuclear Information System (INIS)

Jadeja, K A; Bhatt, S B

2012-01-01

In ultra high vacuum (UHV) range, hydrogen is a dominant residual gas in vacuum chamber. Hydrogen, being light gas, pumping of hydrogen in this vacuum range is limited with widely used UHV pumps, viz. turbo molecular pump and cryogenic pump. Pre condensed argon layers in cryogenic pump create porous structure on the surface of the pump, which traps hydrogen gas at a temperature less than 20° K. Additional argon gas injection in the cryogenic pump, at lowest temperature, generates multiple layers of condensed argon as a porous frost with 10 to 100 A° diameters pores, which increase the pumping capacity of hydrogen gas. This pumping mechanism of hydrogen is more effective, to pump more hydrogen gas in UHV range applicable in accelerator, space simulation etc. and where hydrogen is used as fuel gas like tokamak. For this experiment, the cryogenic pump with a closed loop refrigerator using helium gas is used to produce the minimum cryogenic temperature as ∼ 14° K. In this paper, effect of cryosorption of hydrogen is presented with different levels of argon gas and hydrogen gas in cryogenic pump chamber.

Materials selection, qualification and manufacturing of the in-vessel divertor cryopump for JET

International Nuclear Information System (INIS)

Papastergiou, S.; Obert, W.; Thompson, E.

1994-01-01

The introduction of a cryopump into the interior of a large tokamak raises several technical problems related to the thermal stresses, eddy current forces and choice of materials. The JET divertor cryopump has been optimized in terms of stresses, flow stability and operation - the liquid nitrogen cooled chevron structure in particular having to fulfill conflicting requirements at cryogenic temperatures. These requirements include good thermal conductivity in order to minimize thermal gradients (to reduce the radiative heat load onto the liquid helium circuit), high electrical resistivity (to minimize eddy current stresses), high mechanical strength and good mechanical formability. This paper reports on the materials selection based on measurements of properties at cryogenic and elevated temperatures and the development of an optimized thermal treatment combining solution heat treatment, brazing and precipitation hardening. It also reports on the successful development of various manufacturing technologies which have been employed including (a) techniques for brazing of the chosen copper alloy onto inconel and stainless steel, (b) surface blackening of the copper alloy with plasma sprayed ceramic coatings that are vacuum compatible and able to withstand temperatures between 70 K and 1135 K and (c) plasma spray deposition of copper onto stainless steel in order to produce an anisotropic composite material with improved thermal conductivity, high strength and high electrical resistivity for use at temperatures between 70 K and 650 K

How endangered is sexual reproduction of high-mountain plants by summer frosts? Frost resistance, frequency of frost events and risk assessment.

Science.gov (United States)

Ladinig, Ursula; Hacker, Jürgen; Neuner, Gilbert; Wagner, Johanna

2013-03-01

In temperate-zone mountains, summer frosts usually occur during unpredictable cold spells with snow-falls. Earlier studies have shown that vegetative aboveground organs of most high-mountain plants tolerate extracellular ice in the active state. However, little is known about the impact of frost on reproductive development and reproductive success. In common plant species from the European Alps (Cerastium uniflorum, Loiseleuria procumbens, Ranunculus glacialis, Rhododendron ferrugineum, Saxifraga bryoides, S. moschata, S. caesia), differing in growth form, altitudinal distribution and phenology, frost resistance of reproductive and vegetative shoots was assessed in different reproductive stages. Intact plants were exposed to simulated night frosts between -2 and -14 °C in temperature-controlled freezers. Nucleation temperatures, freezing damage and subsequent reproductive success (fruit and seed set, seed germination) were determined. During all reproductive stages, reproductive shoots were significantly less frost resistant than vegetative shoots (mean difference for LT50 -4.2 ± 2.7 K). In most species, reproductive shoots were ice tolerant before bolting and during fruiting (mean LT50 -7 and -5.7 °C), but were ice sensitive during bolting and anthesis (mean LT50 around -4 °C). Only R. glacialis remained ice tolerant during all reproductive stages. Frost injury in reproductive shoots usually led to full fruit loss. Reproductive success of frost-treated but undamaged shoots did not differ significantly from control values. Assessing the frost damage risk on the basis of summer frost frequency and frost resistance shows that, in the alpine zone, low-statured species are rarely endangered as long as they are protected by snow. The situation is different in the subnival and nival zone, where frost-sensitive reproductive shoots may become frost damaged even when covered by snow. Unprotected individuals are at high risk of suffering from frost damage, particularly

Shutdown dose rates at ITER equatorial ports considering radiation cross-talk from torus cryopump lower port

Energy Technology Data Exchange (ETDEWEB)

Juárez, Rafael, E-mail: rjuarez@ind.uned.es [Departamento de Ingeniería Energética, ETSII-UNED, Calle Juan del Rosal 12, Madrid 28040 (Spain); Pampin, Raul [F4E, Torres Diagonal Litoral B3, Josep Pla 2, Barcelona 08019 (Spain); Levesy, Bruno [ITER Organization, 13115 Route de Vinon sur Verdon, St Paul Lez Durance (France); Moro, Fabio [ENEA, Via Enrico Fermi 45, Frascati, Rome (Italy); Suarez, Alejandro [ITER Organization, 13115 Route de Vinon sur Verdon, St Paul Lez Durance (France); Sanz, Javier [Departamento de Ingeniería Energética, ETSII-UNED, Calle Juan del Rosal 12, Madrid 28040 (Spain)

2015-11-15

Shutdown dose rates for planned maintenance purposes is an active research field in ITER. In this work the radiation (neutron and gamma) cross-talk between ports in the most conservative case foreseen in ITER is investigated: the presence of a torus cryopump lower port, mostly empty for pumping efficiency reasons. There will be six of those ports: #4, #6, #10, #12, #16 and #18. The equatorial ports placed above them will receive a significant amount of additional radiation affecting the shutdown dose rates during in situ maintenance activities inside the cryostat, and particularly in the port interspace area. In this study a general situation to all the equatorial ports placed above torus cryopump lower ports is considered: a generic diagnostics equatorial port placed above the torus cryopump lower port (LP#4). In terms of shutdown dose rates at equatorial port interspace after 10{sup 6} s of cooling time, 405 μSv/h has been obtained, of which 160 μSv/h (40%) are exclusively due to radiation cross-talk from a torus cryopump lower port. Equatorial port activation due to only “local neutrons” contributes 166 μSv/h at port interspace, showing that radiation cross-talk from such a lower port is a phenomenon comparable in magnitude to the neutron leakage though the equatorial port plug.

Regeneration and tritium recovery from the large JET neutral injection cryopump system after the FTE

International Nuclear Information System (INIS)

Obert, W.; Bell, A.; Davies, J.; Mayaux, C.; Perinic, G.; Saibene, G.; Sartori, R.; Thompson, E.; Anderson, J.; Jenkins, E.; Walthers, C.

1992-01-01

Neutral Beam Injection (NBI) was used to introduce tritium into the plasma for the First Tritium Experiment In addition to the decisive advantage of depositing the tritium into the centre of the plasma, the use of NBI also minimized the total quantity of tritium introduced into the Torus and the contamination of the vacuum vessel. However, because of the relatively low gas efficiency of the positive ion injection system approximately 95% of the total quantity of tritium introduced was pumped by the large condensation cryopumps which form an integral part of the injector. Several hardware and associated software changes were implemented in order to making provision for possible fault scenarios during operation with tritium and to ensure complete regeneration of the tritium from the cryopumps. The tritium released after all subsequent regeneration's has been monitored carefully in order to determine the amount of tritium retained by the black anodized liquid nitrogen panel surfaces of the cryopump and to compare it with experiments at TSTA on JET samples before the FTE

Nuclear analysis of the ITER Cryopump Ports

International Nuclear Information System (INIS)

Moro, Fabio; Villari, Rosaria; Flammini, Davide; Antipenkov, Alexander; Dremel, Matthias; Levesy, Bruno; Loughlin, Michael; Juarez, Rafael; Perez, Lucia; Petrizzi, Luigino

2015-01-01

Highlights: • Evaluation the shielding effectiveness of the TCPHs by means of 3-D neutrons and gamma maps. • Assessment of the nuclear heating induced by neutron and photons on the TCP and TCPHs. • Calculation of the dose rate at 12 days after shutdown in the maintenance area of the Lower Ports with the Advanced D1S method, in order to verify the design target (100 μSv/h). • Potential improvements of the shielding configuration aimed at the reduction of the dose level in the Port Cell have been proposed and discussed. - Abstract: The ITER machine will be equipped with 6 torus Cryopumps (TCP) that are positioned in their housings (TCPH) and integrated into the cryostat walls at B1 level in the port cells. A comprehensive nuclear analysis of the Cryopump Ports #4 and #12 has been carried out by means of the MCNP-5 Monte Carlo code in a full 3-D geometry, providing guidelines for the design of the embedded components. Radiation transport calculations have been performed in order to determine the radiation field inside the Lower Ports, up the Port Cell: 3-D neutrons and gamma maps have been provided in order to evaluate the shielding effectiveness of the TCPHs. Nuclear heating induced by neutron and photons have been estimated on the TCP and TCPH to assess the nuclear loads during plasma operations. The shutdown dose rate in the maintenance area of the Lower Ports has been assessed with the Advanced D1S method to verify the design limits.

Nuclear analysis of the ITER Cryopump Ports

Energy Technology Data Exchange (ETDEWEB)

Moro, Fabio, E-mail: fabio.moro@enea.it [ENEA, Fusion Technical Unit, Nuclear Technologies Laboratory, Via Enrico Fermi 45, 00044 Frascati, Rome (Italy); Villari, Rosaria; Flammini, Davide [ENEA, Fusion Technical Unit, Nuclear Technologies Laboratory, Via Enrico Fermi 45, 00044 Frascati, Rome (Italy); Antipenkov, Alexander; Dremel, Matthias; Levesy, Bruno; Loughlin, Michael [ITER Organization, Route de Vinon sur Verdon, 13115 Saint Paul-lez-Durance (France); Juarez, Rafael; Perez, Lucia [UNED, Energetic Engineering Department, C/Juan del Rosal 12, Madrid (Spain); Petrizzi, Luigino [European Commission, DG Research & Innovation G5, CDMA 00/030, B-1049 Brussels (Belgium)

2015-10-15

Highlights: • Evaluation the shielding effectiveness of the TCPHs by means of 3-D neutrons and gamma maps. • Assessment of the nuclear heating induced by neutron and photons on the TCP and TCPHs. • Calculation of the dose rate at 12 days after shutdown in the maintenance area of the Lower Ports with the Advanced D1S method, in order to verify the design target (100 μSv/h). • Potential improvements of the shielding configuration aimed at the reduction of the dose level in the Port Cell have been proposed and discussed. - Abstract: The ITER machine will be equipped with 6 torus Cryopumps (TCP) that are positioned in their housings (TCPH) and integrated into the cryostat walls at B1 level in the port cells. A comprehensive nuclear analysis of the Cryopump Ports #4 and #12 has been carried out by means of the MCNP-5 Monte Carlo code in a full 3-D geometry, providing guidelines for the design of the embedded components. Radiation transport calculations have been performed in order to determine the radiation field inside the Lower Ports, up the Port Cell: 3-D neutrons and gamma maps have been provided in order to evaluate the shielding effectiveness of the TCPHs. Nuclear heating induced by neutron and photons have been estimated on the TCP and TCPH to assess the nuclear loads during plasma operations. The shutdown dose rate in the maintenance area of the Lower Ports has been assessed with the Advanced D1S method to verify the design limits.

Summarized results of the cryosorption panel test programme for the ITER cryopumping system

International Nuclear Information System (INIS)

Day, C.; Haas, H.; Mack, A.; Kazakovsky, N.T.; Murdoch, D.K.; Roehrig, D.; Saksagansky, G.L.

2001-01-01

A reliable but versatile primary cryopumping system is required for high vacuum pumping of the ITER torus during all phases of plasma operation. To achieve that goal, an extensive R and D programme has been performed within the framework of the Nuclear Fusion Project of FZK, supported by the European Communities under the European Fusion Technology Programme. The present paper covers that part of the programme, which focuses on the pumping speed of the recommended cryopanel type and the various aspects of the charcoal-bonding system in the cryogenic temperature range. It is demonstrated that the investigated cryosorption panels exhibit a very good behaviour with respect to pumping efficiency, long-term thermomechanical endurance and compatibility with tritium. The recommended cryopump design was therefore chosen as point design for ITER. (author)

A study on frost formation

OpenAIRE

青木, 和夫

1986-01-01

When humid air is exposed to a cold surface whose temperature is below 0 \\C\\, frost deposition occurs and continues to accumulate on the surface. Frost deposition is an important phenomenon in cryogenic industries for use in air conditioners, refrigerators and freeze-out purification, because it causes the drop of thermal efficiency on heat exchangers.This paper presented a review of our previous studies on frost formation with emphasis on the frost growth process, the frost structure, the gr...

Enhanced by Frost

Science.gov (United States)

2005-01-01

30 September 2005 This Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC) image shows outcrops of south polar layered terrain. Their appearance in this July 2005 springtime image is enhanced by bright patches of carbon dioxide frost. The frost is left over from the previous southern winter season; by summer, the frost would be gone. Location near: 84.6oS, 203.5oW Image width: width: 3 km (1.9 mi) Illumination from: upper left Season: Southern Spring

Frost on Utopia Planitia

Science.gov (United States)

1977-01-01

This Viking Lander 2 picture from Utopia Planitia shows the first clear indication of frost accumulation on the Martian surface seen by lander cameras. The picture, looking due north, was obtained with a blue filter at 12:59 p.m. local lander time, Sept. 13, 1977. The season is late winter. Frost appears as a white accumulation around the bottom of rocks, in a trench dug by the lander sampler arm, and in scattered patches on the darker surface. The shadow of the lander, including the camera (center) and the meteorology boom (left), appears in foreground. As the sun moves, the shadow is moving from left to right, exposing areas covered by frost and previously protected from the sun by the lander shadow. (Another image taken one-half hour later suggests the frost patches have become smaller.) Apparently frost, formed during the Martian night, at least partially disappears during the warmer daytime. The composition of the frost, whether carbon dioxide or water or a mixture of the two (CO2 clathrate), is not known. Measurements from the meteorology instrument indicate minimum nighttime temperatures of 160 Kelvin (-171 Fahrenheit). At the time the image was taken, the temperature had risen to 175 Kelvin (-144 Fahrenheit). The atmospheric pressure was 8.835 millibars. This combination of pressure and temperature are inconsistent with carbon dioxide frost formation, but plausible near-surface mechanisms might have resulted in conditions favorable for CO2 frost formation. Viking orbiter thermal mapping and water vapor instruments indicate temperatures might have been slightly lower than measured by the lander, suggesting that the frost is more likely CO2 than H20. A remote, but possible, explanation is that the material is an extremely bright dust deposit. Color images to be taken will be able to discount this interpretation. The mechanism for frost deposition is unknown. Possibilities include formation directly on the surface, precipitation as snow, or material blown to

CW gain measurements in small-bore argon-ion laser discharges using a novel modulation technique

International Nuclear Information System (INIS)

Bennett, W.R. Jr.; Sze, R.C.

1974-01-01

A technique for small-signal gain measurements for cw laser systems is described. The method is applied to the measurement of multimode small-signal gain coefficients of small-bone argon-ion laser transitions. (U.S.)

Assessing frost damages using dynamic models in walnut trees: exposure rather than vulnerability controls frost risks.

Science.gov (United States)

Guillaume, Charrier; Isabelle, Chuine; Marc, Bonhomme; Thierry, Améglio

2018-05-01

Frost damages develop when exposure overtakes frost vulnerability. Frost risk assessment therefore needs dynamic simulation of frost hardiness using temperature and photoperiod in interaction with developmental stage. Two models, including or not the effect of photoperiod, were calibrated using five years of frost hardiness monitoring (2007-2012), in two locations (low and high elevation) for three walnut genotypes with contrasted phenology and maximum hardiness (Juglans regia cv Franquette, J. regia × nigra 'Early' and 'Late'). The photothermal model predicted more accurate values for all genotypes (efficiency = 0.879; Root Mean Standard Error Predicted (RMSEP) = 2.55 °C) than the thermal model (efficiency = 0.801; RMSEP = 3.24 °C). Predicted frost damages were strongly correlated to minimum temperature of the freezing events (ρ = -0.983) rather than actual frost hardiness (ρ = -0.515), or ratio of phenological stage completion (ρ = 0.336). Higher frost risks are consequently predicted during winter, at high elevation, whereas spring is only risky at low elevation in early genotypes exhibiting faster dehardening rate. However, early frost damages, although of lower value, may negatively affect fruit production the subsequent year (R 2  = 0.381, P = 0.057). These results highlight the interacting pattern between frost exposure and vulnerability at different scales and the necessity of intra-organ studies to understand the time course of frost vulnerability in flower buds along the winter. © 2017 John Wiley & Sons Ltd.

Frost heave in He

International Nuclear Information System (INIS)

Mizusaki, T.; Hiroi, M.

1995-01-01

Frost heave occurs in various phenomena in natural environment. It has been studied in helium on porous glasses under perfect ice-segregation condition. The maximum frost heave pressure was investigated for various conditions and was in good agreement with the thermodynamical prediction. The dynamical properties of frost heave are discussed and some of the preliminary results of the growth rate measurement are presented. (orig.)

QTL analysis of frost damage in pea suggests different mechanisms involved in frost tolerance.

Science.gov (United States)

Klein, Anthony; Houtin, Hervé; Rond, Céline; Marget, Pascal; Jacquin, Françoise; Boucherot, Karen; Huart, Myriam; Rivière, Nathalie; Boutet, Gilles; Lejeune-Hénaut, Isabelle; Burstin, Judith

2014-06-01

Avoidance mechanisms and intrinsic resistance are complementary strategies to improve winter frost tolerance and yield potential in field pea. The development of the winter pea crop represents a major challenge to expand plant protein production in temperate areas. Breeding winter cultivars requires the combination of freezing tolerance as well as high seed productivity and quality. In this context, we investigated the genetic determinism of winter frost tolerance and assessed its genetic relationship with yield and developmental traits. Using a newly identified source of frost resistance, we developed a population of recombinant inbred lines and evaluated it in six environments in Dijon and Clermont-Ferrand between 2005 and 2010. We developed a genetic map comprising 679 markers distributed over seven linkage groups and covering 947.1 cM. One hundred sixty-one quantitative trait loci (QTL) explaining 9-71 % of the phenotypic variation were detected across the six environments for all traits measured. Two clusters of QTL mapped on the linkage groups III and one cluster on LGVI reveal the genetic links between phenology, morphology, yield-related traits and frost tolerance in winter pea. QTL clusters on LGIII highlighted major developmental gene loci (Hr and Le) and the QTL cluster on LGVI explained up to 71 % of the winter frost damage variation. This suggests that a specific architecture and flowering ideotype defines frost tolerance in winter pea. However, two consistent frost tolerance QTL on LGV were independent of phenology and morphology traits, showing that different protective mechanisms are involved in frost tolerance. Finally, these results suggest that frost tolerance can be bred independently to seed productivity and quality.

Long term pavement performance computed parameter : frost penetration

Science.gov (United States)

2008-11-01

As the pavement design process moves toward mechanistic-empirical techniques, knowledge of seasonal changes in pavement structural characteristics becomes critical. Specifically, frost penetration information is necessary for determining the effect o...

Robert Frost: Teacher "Earner, Learner, Yearner."

Science.gov (United States)

Vogel, Nancy Sue

An account of Robert Frost's teaching, along with an assessment of it, are presented. Material consulted includes Frost's published letters, prose, and poetry; Lawrance Thompson's authorized biography; Lesley Frost's "New Hampshire's Child: The Derry Journals of Lesley Frost;" and additional sources such as films and periodicals,…

Frost resistance in alpine woody plants.

Science.gov (United States)

Neuner, Gilbert

2014-01-01

This report provides a brief review of key findings related to frost resistance in alpine woody plant species, summarizes data on their frost resistance, highlights the importance of freeze avoidance mechanisms, and indicates areas of future research. Freezing temperatures are possible throughout the whole growing period in the alpine life zone. Frost severity, comprised of both intensity and duration, becomes greater with increasing elevation and, there is also a greater probability, that small statured woody plants, may be insulated by snow cover. Several frost survival mechanisms have evolved in woody alpine plants in response to these environmental conditions. Examples of tolerance to extracellular freezing and freeze dehydration, life cycles that allow species to escape frost, and freeze avoidance mechanisms can all be found. Despite their specific adaption to the alpine environment, frost damage can occur in spring, while all alpine woody plants have a low risk of frost damage in winter. Experimental evidence indicates that premature deacclimation in Pinus cembra in the spring, and a limited ability of many species of alpine woody shrubs to rapidly reacclimate when they lose snow cover, resulting in reduced levels of frost resistance in the spring, may be particularly critical under the projected changes in climate. In this review, frost resistance and specific frost survival mechanisms of different organs (leaves, stems, vegetative and reproductive over-wintering buds, flowers, and fruits) and tissues are compared. The seasonal dynamics of frost resistance of leaves of trees, as opposed to woody shrubs, is also discussed. The ability of some tissues and organs to avoid freezing by supercooling, as visualized by high resolution infrared thermography, are also provided. Collectively, the report provides a review of the complex and diverse ways that woody plants survive in the frost dominated environment of the alpine life zone.

Frost resistance of alpine woody plants

Directory of Open Access Journals (Sweden)

Gilbert eNeuner

2014-12-01

Full Text Available This report provides a brief review of key findings related to frost resistance in alpine woody plant species, summarizes data on their frost resistance, highlights the importance of freeze avoidance mechanisms, and indicates areas of future research.Freezing temperatures are possible throughout the whole growing period in the alpine life zone. Frost severity, comprised of both intensity and duration, becomes greater with increasing elevation and, there is also a greater probability, that small statured woody plants, may be insulated by snow cover.Several frost survival mechanisms have evolved in woody alpine plants in response to these environmental conditions. Examples of tolerance to extracellular freezing and freeze dehydration, life cycles that allow species to escape frost, and freeze avoidance mechanisms can all be found. Despite their specific adaption to the alpine environment, frost damage can occur in spring, while all alpine woody plants have a low risk of frost damage in winter. Experimental evidence indicates that premature deacclimation in Pinus cembra in the spring, and a limited ability of many species of alpine woody shrubs to rapidly reacclimate when they lose snow cover, resulting in reduced levels of frost resistance in the spring, may be particularly critical under the projected changes in climate.In this review, frost resistance and specific frost survival mechanisms of different organs (leaves, stems, vegetative and reproductive over-wintering buds, flowers and fruits and tissues are compared. The seasonal dynamics of frost resistance of leaves of trees, as opposed to woody shrubs, is also discussed. The ability of some tissues and organs to avoid freezing by supercooling, as visualized by high resolution infrared thermography, are also provided. Collectively, the report provides a review of the complex and diverse ways that woody plants survive in the frost dominated environment of the alpine life zone.

Validation of myocardial blood flow estimation with nitrogen-13 ammonia PET by the argon inert gas technique in humans

International Nuclear Information System (INIS)

Kotzerke, J.; Glatting, G.; Neumaier, B.; Reske, S.N.; Hoff, J. van den; Hoeher, M.; Woehrle, J. n

2001-01-01

We simultaneously determined global myocardial blood flow (MBF) by the argon inert gas technique and by nitrogen-13 ammonia positron emission tomography (PET) to validate PET-derived MBF values in humans. A total of 19 patients were investigated at rest (n=19) and during adenosine-induced hyperaemia (n=16). Regional coronary artery stenoses were ruled out by angiography. The argon inert gas method uses the difference of arterial and coronary sinus argon concentrations during inhalation of a mixture of 75% argon and 25% oxygen to estimate global MBF. It can be considered as valid as the microspheres technique, which, however, cannot be applied in humans. Dynamic PET was performed after injection of 0.8±0.2 GBq 13 N-ammonia and MBF was calculated applying a two-tissue compartment model. MBF values derived from the argon method at rest and during the hyperaemic state were 1.03±0.24 ml min -1 g -1 and 2.64±1.02 ml min -1 g -1 , respectively. MBF values derived from ammonia PET at rest and during hyperaemia were 0.95±0.23 ml min -1 g -1 and 2.44±0.81 ml min -1 g -1 , respectively. The correlation between the two methods was close (y=0.92x+0.14, r=0.96; P 13 N-ammonia PET. (orig.)

Liquid argon TPC signal formation, signal processing and reconstruction techniques

Science.gov (United States)

Baller, B.

2017-07-01

This document describes a reconstruction chain that was developed for the ArgoNeuT and MicroBooNE experiments at Fermilab. These experiments study accelerator neutrino interactions that occur in a Liquid Argon Time Projection Chamber. Reconstructing the properties of particles produced in these interactions benefits from the knowledge of the micro-physics processes that affect the creation and transport of ionization electrons to the readout system. A wire signal deconvolution technique was developed to convert wire signals to a standard form for hit reconstruction, to remove artifacts in the electronics chain and to remove coherent noise. A unique clustering algorithm reconstructs line-like trajectories and vertices in two dimensions which are then matched to create of 3D objects. These techniques and algorithms are available to all experiments that use the LArSoft suite of software.

Infra-red thermography for detecting frost pockets on snow-covered clear-fellings

International Nuclear Information System (INIS)

Mattsson, J.O.; Odin, H.; Palenius, H.P.

1983-01-01

The purpose of the investigation was to find out if IR-thermography from aircraft could be a useful method for registration and studies of regional variation of frost exposition within an area and of distribution of frost risks within individual felling areas. The technique, which was successful, has up till now not been utilized in Sweden for such studies in woodland

Polygons in Martian Frost

Science.gov (United States)

2003-01-01

MGS MOC Release No. MOC2-428, 21 July 2003This June 2003 Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC) image shows a polygonal pattern developed in seasonal carbon dioxide frost in the martian southern hemisphere. The frost accumulated during the recent southern winter; it is now spring, and the carbon dioxide frost is subliming away. This image is located near 80.4oS, 200.2oW; it is illuminated by sunlight from the upper left, and covers an area 3 km (1.9 mi) across.

Polarization spectroscopy of the sodium dimer utilizing a triple-resonance technique in the presence of argon

Science.gov (United States)

Arndt, Phillip; Horton, Timothy; McFarland, Jacob; Bayram, Burcin; Miami University Spectroscopy Team

2015-05-01

The collisional dynamics of molecular sodium in the 61Σg electronic state is under investigation using a triple resonance technique in the presence of argon. A continuous wave ring dye laser is used to populate specific rovibrational levels of the A1Σu electronic state. A pump-probe technique is then employed where the pump laser populates the 61Σg state, and the probe laser dumps the population to the B1Σu state. From this level, fluorescence is detected as the system decays to the X1Σg state. We measure the polarization of this signal in the presence of various argon pressures. We will present our current work as well as the processes involved in the experiment. Financial support from the National Science Foundation (Grant No. NSF-PHY-1309571) is gratefully acknowledged.

The periglacial engine of mountain erosion – Part 1: Rates of frost cracking and frost creep

DEFF Research Database (Denmark)

Andersen, Jane Lund; Egholm, David Lundbek; Knudsen, Mads Faurschou

2015-01-01

present a new model that quantifies two key physical processes: frost cracking and frost creep, as a function of both temperature and sediment thickness. Our results yield new insights into how climate and sediment transport properties combine to scale the intensity of periglacial processes. The thickness...... of the soil mantle strongly modulates the relation between climate and the intensity of mechanical weathering and sediment flux. Our results also point to an offset between the conditions that promote frost cracking and those that promote frost creep, indicating that a stable climate can provide optimal...

Frost on Mars Rover Opportunity

Science.gov (United States)

2004-01-01

Frost can form on surfaces if enough water is present and the temperature is sufficiently low. On each of NASA's Mars Exploration Rovers, the calibration target for the panoramic camera provides a good place to look for such events. A thin frost was observed by Opportunity's panoramic camera on the rover's 257th sol (Oct. 13, 2004) 11 minutes after sunrise (left image). The presence of the frost is most clearly seen on the post in the center of the target, particularly when compared with the unsegmented outer ring of the target, which is white. The post is normally black. For comparison, note the difference in appearance in the image on the right, taken about three hours later, after the frost had dissipated. Frost has not been observed at Spirit, where the amount of atmospheric water vapor is observed to be appreciably lower. Both images were taken through a filter centered at a wavelength of 440 nanometers (blue).

Frost at the Viking Lander 2 Site

Science.gov (United States)

1977-01-01

Photo from Viking Lander 2 shows late-winter frost on the ground on Mars around the lander. The view is southeast over the top of Lander 2, and shows patches of frost around dark rocks. The surface is reddish-brown; the dark rocks vary in size from 10 centimeters (four inches) to 76 centimeters (30 inches) in diameter. This picture was obtained Sept. 25, 1977. The frost deposits were detected for the first time 12 Martian days (sols) earlier in a black-and-white image. Color differences between the white frost and the reddish soil confirm that we are observing frost. The Lander Imaging Team is trying to determine if frost deposits routinely form due to cold night temperatures, then disappear during the warmer daytime. Preliminary analysis, however, indicates the frost was on the ground for some time and is disappearing over many days. That suggests to scientists that the frost is not frozen carbon dioxide (dry ice) but is more likely a carbon dioxide clathrate (six parts water to one part carbon dioxide). Detailed studies of the frost formation and disappearance, in conjunction with temperature measurements from the lander's meteorology experiment, should be able to confirm or deny that hypothesis, scientists say.

Frosting characteristics and heating performance of a direct-expansion solar-assisted heat pump for space heating under frosting conditions

International Nuclear Information System (INIS)

Huang, Wenzhu; Ji, Jie; Xu, Ning; Li, Guiqiang

2016-01-01

Highlights: • Frosting and heating performance of DX-SAHP under frosting conditions is investigated. • The conditions when DX-SAHP frosts are studied. • The frosting process is observed during 360 min of operating. • The effect of ambient temperature, relative humidity and solar irradiation is analyzed. - Abstract: Direct expansion solar-assisted heat pump system (DX-SAHP) is promising in energy saving applications, but the performance of DX-SAHP under frosting conditions is rarely reported in the published literatures. In this paper, a DX-SAHP system with bare solar collectors for space heating is designed and experimentally investigated in the enthalpy difference lab with a solar simulator. The system is tested under a range of frosting conditions, with the ambient temperatures from 7 °C to −3 °C, the relative humidities of 50%, 70% and 90% and the solar irradiances of 0 W/m"2, 100 W/m"2, 200 W/m"2 and 300 W/m"2. The conditions when the DX-SAHP system frosts are studied. Results show that solar irradiance as low as 100 W/m"2 can totally prevent frosting when the ambient temperature is above −3 °C and the relative humidity is 70%. Besides, the frosting process is observed to be slower than that of fin-and-tube heat exchangers. The evaporator is not seriously frosted and the system performance is not significantly influenced after 360 min of continuous operating. Moreover the effects of ambient parameters, including the ambient temperature and the relative humidity, especially solar irradiation, on the system performance are studied and analyzed. Solar irradiation can effectively prevent or retard frosting, and also improve the heating performance of the DX-SAHP system. The DX-SAHP system is proved to be applicable under frosting conditions.

Liquid argon calorimetry for the SSC

International Nuclear Information System (INIS)

Gordon, H.A.

1990-01-01

Liquid argon calorimetry is a mature technique. However, adapting it to the challenging environment of the SSC requires a large amount of R ampersand D. The advantages of the liquid argon approach are summarized and the issues being addressed by the R ampersand D program are described. 18 refs

TSTA compound cryopump

International Nuclear Information System (INIS)

Batzer, T.H.; Patrick, R.E.; Call, W.R.

1980-01-01

The Tritium System Test Assembly (TSTA), at the Los Alamos Scientific Laboratory, is intended to demonstrate realistic fuel supply and cleanup scenarios for future fusion reactors. The vacuum pumps must be capable of handling large quantities of reactor exhaust gases consisting largely of mixtures of hydrogen and helium isotopes. Cryocondensing pumps will not pump helium at 4.2 K; while cryosorption pumps using molecular sieves or charcoal have good helium pumping speed, the adsorbent clogs with condensed hydrogen while pumping mixtures of both. A solution to this problem is a compound design whereby the first stage condenses the hydrogen and the second, or sorption, stage pumps the helium. The TSTA pump designed at Lawrence Livermore National Laboratory uses argon gas to cryotrap the helium in the helium-hydrogen mixture. The argon is sprayed directly onto the 4.2 K surface at a rate proportional to the helium flow rate, permitting continuous pumping of the helium-hydrogen mixtures in a single-stage pump. However, the possibility of differential desorption as a first stage in the TSTA gas separation cycle required the inclusion of a first-stage hydrogen isotope condenser. The design, performance, and operating characteristics are discussed

Prediction of Frost Occurrences Using Statistical Modeling Approaches

Directory of Open Access Journals (Sweden)

Hyojin Lee

2016-01-01

Full Text Available We developed the frost prediction models in spring in Korea using logistic regression and decision tree techniques. Hit Rate (HR, Probability of Detection (POD, and False Alarm Rate (FAR from both models were calculated and compared. Threshold values for the logistic regression models were selected to maximize HR and POD and minimize FAR for each station, and the split for the decision tree models was stopped when change in entropy was relatively small. Average HR values were 0.92 and 0.91 for logistic regression and decision tree techniques, respectively, average POD values were 0.78 and 0.80 for logistic regression and decision tree techniques, respectively, and average FAR values were 0.22 and 0.28 for logistic regression and decision tree techniques, respectively. The average numbers of selected explanatory variables were 5.7 and 2.3 for logistic regression and decision tree techniques, respectively. Fewer explanatory variables can be more appropriate for operational activities to provide a timely warning for the prevention of the frost damages to agricultural crops. We concluded that the decision tree model can be more useful for the timely warning system. It is recommended that the models should be improved to reflect local topological features.

[Comparison of red edge parameters of winter wheat canopy under late frost stress].

Science.gov (United States)

Wu, Yong-feng; Hu, Xin; Lü, Guo-hua; Ren, De-chao; Jiang, Wei-guo; Song, Ji-qing

2014-08-01

In the present study, late frost experiments were implemented under a range of subfreezing temperatures (-1 - -9 degrees C) by using a field movable climate chamber (FMCC) and a cold climate chamber, respectively. Based on the spectra of winter wheat canopy measured at noon on the first day after the frost experiments, red edge parameters REP, Dr, SDr, Dr(min), Dr/Dr(min) and Dr/SDr were extracted using maximum first derivative spectrum method (FD), linear four-point interpolation method (FPI), polynomial fitting method (POLY), inverted Gaussian fitting method (IG) and linear extrapolation technique (LE), respectively. The capacity of the red edge parameters to detect late frost stress was explicated from the aspects of the early, sensitivity and stability through correlation analysis, linear regression modeling and fluctuation analysis. The result indicates that except for REP calculated from FPI and IG method in Experiment 1, REP from the other methods was correlated with frost temperatures (P frost temperatures (P frost temperatures which indicated that LE method is the best for REP extraction. In Experiment 1 and 2, only Dr(min) and Dr/Dr(min), calculated by FD method simultaneously achieved the requirements for the early (their correlations with frost temperatures showed a significant level P frost temperatures al- ways keep a consistent direction). Dr/SDr calculated from FD and IG methods always had a low sensitivity in Experiment 2. In Experiment 1, the sensitivity of Dr/SDr from FD was moderate and IG was high. REP calculated from LE method had a lowest sensitivity in the two experiments. Totally, Dr(min) and Dr/Dr(min) calculated by FD method have the strongest detection capacity for frost temperature, which will be helpful to conducting the research on early diagnosis of late frost injury to winter wheat.

Argon analytical procedures for potassium-argon dating

International Nuclear Information System (INIS)

Gabites, J.E.; Adams, C.J.

1981-01-01

A manual for the argon analytical methods involved in potassium-argon geochronology, including: i) operating procedures for the ultra-high vacuum argon extraction/purification equipment for the analysis of nanolitre quantities of radiogenic argon in rocks, minerals and gases; ii) operating procedures for the AEI-MS10 gas source mass spectrometer

12,000 l/sec cryopump for hydrogen gas

International Nuclear Information System (INIS)

Shibata, Takemasa; Matsuda, Shinzaburo; Shirakata, Hirofumi; Saito, Masaki; Mizuno, Masayasu.

1978-08-01

In the neutral beam injector of JT-60, cryogenic pumps with pumping rate 10 6 l/sec for hydrogen will be installed in the beam lines. To develop the cryopumps a small-scale pump of 12,000 l/sec was made and its fundamental pumping characteristics were measured. The cryogenic pump consists of liquid helium cooled panel, liquid nitrogen cooled chevron and radiation shields. The cryopanel is cylindrical form and the chevron is arranged concentrically within it. The measured pumping rate agrees with the design one. The pumping rate is not lowered by 30 Torr.l/cm 2 on the cryopanel. Liquid helium consumption rate was also measured and the pressure rise in the vacuum chamber in reactivation of the cryopanel was observed. (auth.)

Frost Growth and Densification in Laminar Flow Over Flat Surfaces

Science.gov (United States)

Kandula, Max

2011-01-01

One-dimensional frost growth and densification in laminar flow over flat surfaces has been theoretically investigated. Improved representations of frost density and effective thermal conductivity applicable to a wide range of frost circumstances have been incorporated. The validity of the proposed model considering heat and mass diffusion in the frost layer is tested by a comparison of the predictions with data from various investigators for frost parameters including frost thickness, frost surface temperature, frost density and heat flux. The test conditions cover a range of wall temperature, air humidity ratio, air velocity, and air temperature, and the effect of these variables on the frost parameters has been exemplified. Satisfactory agreement is achieved between the model predictions and the various test data considered. The prevailing uncertainties concerning the role air velocity and air temperature on frost development have been elucidated. It is concluded that that for flat surfaces increases in air velocity have no appreciable effect on frost thickness but contribute to significant frost densification, while increase in air temperatures results in a slight increase the frost thickness and appreciable frost densification.

How endangered is sexual reproduction of high-mountain plants by summer frosts? Frost resistance, frequency of frost events and risk assessment

OpenAIRE

Ladinig, Ursula; Hacker, J?rgen; Neuner, Gilbert; Wagner, Johanna

2013-01-01

In temperate-zone mountains, summer frosts usually occur during unpredictable cold spells with snow-falls. Earlier studies have shown that vegetative aboveground organs of most high-mountain plants tolerate extracellular ice in the active state. However, little is known about the impact of frost on reproductive development and reproductive success. In common plant species from the European Alps (Cerastium uniflorum, Loiseleuria procumbens, Ranunculus glacialis, Rhododendron ferrugineum, Saxif...

Frost on Mars

Science.gov (United States)

2008-01-01

This image shows bluish-white frost seen on the Martian surface near NASA's Phoenix Mars Lander. The image was taken by the lander's Surface Stereo Imager on the 131st Martian day, or sol, of the mission (Oct. 7, 2008). Frost is expected to continue to appear in images as fall, then winter approach Mars' northern plains. The Phoenix Mission is led by the University of Arizona, Tucson, on behalf of NASA. Project management of the mission is by NASA's Jet Propulsion Laboratory, Pasadena, Calif. Spacecraft development is by Lockheed Martin Space Systems, Denver.

Characterising the light output from Argon bombs by two simultaneous diagnostic techniques

CSIR Research Space (South Africa)

Olivier, M

2013-01-01

Full Text Available The light output from Argon-bombs was investigated by means of ultra high speed photography (Cordin Model 550-32 camera) and locally developed photodiode sensors. Tubes of various sizes were inflated with Argon gas, and were detonated on one side...

Conducting field trials for frost tolerance breeding in cereals.

Science.gov (United States)

Cattivelli, Luigi

2014-01-01

Cereal species can be damaged by frost either during winter or at flowering stage. Frost tolerance per se is only a part of the mechanisms that allow the plants to survive during winter; winterhardiness also considers other biotic or physical stresses that challenge the plants during the winter season limiting their survival rate. While frost tolerance can also be tested in controlled environments, winterhardiness can be determined only with field evaluations. Post-heading frost damage occurs from radiation frost events in spring during the reproductive stages. A reliable evaluation of winterhardiness or of post-heading frost damage should be carried out with field trials replicated across years and locations to overcome the irregular occurrence of natural conditions which satisfactorily differentiate genotypes. The evaluation of post-heading frost damage requires a specific attention to plant phenology. The extent of frost damage is usually determined with a visual score at the end of the winter.

Frost heave modelling of buried pipelines using non-linear Fourier finite elements

International Nuclear Information System (INIS)

Wan, R. G.; You, R.

1998-01-01

Numerical analysis of the response of a three-dimensional soil-pipeline system in a freezing environment using non-linear Fourier finite elements was described as an illustration of the effectiveness of this technique in analyzing plasticity problems. Plastic deformations occur when buried pipeline is under the action of non-uniform frost heave. The three-dimensional frost heave which develops over time including elastoplastic deformations of the soil and pipe are computed. The soil heave profile obtained in the numerical analysis was consistent with experimental findings for similar configurations. 8 refs., 8 figs

A Gentle Frost: Poet Helen Frost Talks about the Healing Power of Poetry and Her Latest Novel

Science.gov (United States)

Margolis, Rick

2006-01-01

This article presents an interview with poet Helen Frost. Frost talked about how poetry can help at-risk children. She also related the challenges she faced when she wrote her latest book titled "The Braid."

Experimental confirmation of the ITER cryopump high temperature regeneration scheme

International Nuclear Information System (INIS)

Day, C.; Haas, H.

2007-01-01

Forschungszentrum Karlsruhe (FZK) is developing the ITER high vacuum pumping systems for evacuation and maintenance of the required pressure levels in the torus (during burn and dwell, conditioning and leak detection), the neutral beam injectors and the cryostat vessel. All ITER high vacuum systems share the same concept of accumulative cryosorption pumping. The pumping surfaces, forced-cooled by 4.5 K supercritical helium, are coated with activated charcoal so as to be able to adsorb helium and hydrogens. All other gases are cryopumped by cryogenic phase transition from gaseous into the liquid/solid state. For the hydrogen processing pumps in the torus and the NBI, the maximum pumping time is given by the limitation of the maximum hydrogen inventory such that the resulting pressure in case of a loss of vacuum event and a corresponding oxy-hydrogen explosion is compatible to the design criteria of the vacuum vessel. To limit the gas accumulation, a staggered regeneration philosophy has been adopted, which involves three different temperature levels in order to achieve high regeneration efficiencies at best availability of the pumping system. The regular regeneration step is performed at a charcoal temperature of 90 K to release all hydrogen isotopomers (and helium), which are subsequently pumped out by the forevacuum pumping system. The second step at ambient temperature leads to the release of all air-like species. It has to be performed less frequently, probably over-night. Any water-like species with strong sorption bonding forces need still higher temperatures for effective desorption from the charcoal. These species comprise not only water itself but also high molecular tracers added to the water circuits in case of leak localisation and any pumped higher hydrocarbons from the plasma exhaust or. The latter in their tritiated forms may contribute significantly to the semi-permanent tritium inventory; a good knowledge of their regeneration characteristics is

[Infrared spectroscopic analysis of Guilin watermelon frost products].

Science.gov (United States)

Huang, Dong-lan; Chen, Xiao-kang; Xu, Yong-qun; Sun, Su-qin; Zhou, Qun; Lu, Wen-guan

2012-08-01

The objective of the present study is to analyze different products of Guilin watermelon frost by Fourier transform infrared spectroscopy (FTIR), second derivative infrared spectroscopy and two-dimensional correlation spectroscopy (2D-IR) under thermal perturbation. The structural information of the samples indicates that samples from the same factory but of different brands had some dissimilarities in the IR spectra, and the type and content of accessories of them were different compared with conventional IR spectra of samples, peaks at 638 and 616 cm(-1) all arise from anhydrous sodium sulfate in watermelon frost spray and watermelon frost capsule; the characteristic absorption peaks of the sucrose, dextrin or other accessories can be seen clearly in the spectra of watermelon frost throat-clearing buccal tablets, watermelon frost throat tablets and watermelon frost lozenge. And the IR spectra of watermelon frost lozenge is very similar to the IR spectra of sucrose, so it can be easily proved that the content of sucrose in watermelon frost lozenge is high. In the 2D-IR correlation spectra, the samples presented the differences in the position, number and relative intensity of autopeaks and correlation peak clusters. Consequently, the macroscopical fingerprint characters of FTIR, second derivative infrared spectra and 2D-IR spectra can not only provide the information about main chemical constituents in medical materials, but also analyze and identify the type and content of accessories in Guilin watermelon frost. In conclusion, the multi-steps IR macro-fingerprint method is rapid, effective, visual and accurate for pharmaceutical research.

Visualization of frosting phenomena by using neutron radiography

International Nuclear Information System (INIS)

Yoshimura, Tomoya; Matsumoto, Ryosuke; Umekawa, Hisashi; Ami, Takeyuki; Saito, Yasushi

2012-01-01

This study focuses on the frost formation on the fin-tube heat exchanger using neutron radiography. The visualization of the frost formation was estimated by the attenuation of the neutron beam through the water. The visualization image of the neutron radiography shows clearly the frost formation phenomena on the fin-tube heat exchanger. The rapid frost formation was observed at the fin and tube edges. Local mass transfer coefficient can be calculated from the differential images of the neutron radiography. (author)

Frost risks in the Mantaro river basin

Directory of Open Access Journals (Sweden)

G. Trasmonte

2008-04-01

Full Text Available As part of the study on the Mantaro river basin's (central Andes of Perú current vulnerability to climate change, the temporal and spatial characteristics of frosts were analysed. These characteristics included intensity, frequency, duration, frost-free periods, area distribution and historical trends. Maps of frost risk were determined for the entire river basin, by means of mathematical algorithms and GIS (Geographic Information Systems tools, using minimum temperature – 1960 to 2002 period, geomorphology, slope, land-use, types of soils, vegetation and life zones, emphasizing the rainy season (September to April, when the impacts of frost on agriculture are most severe. We recognized four categories of frost risks: low, moderate, high and critical. The critical risks (with a very high probability of occurrence were related to high altitudes on the basin (altitudes higher than 3800 m a.s.l., while the low (or null probability of occurring risks were found in the lower zones (less than 2500 m a.s.l.. Because of the very intense agricultural activity and the high sensitivity of the main crops (Maize, potato, artichoke in the Mantaro valley (altitudes between 3100 and 3300 m a.s.l., moderate to high frost risks can be expected, with a low to moderate probability of occurrence. Another significant result was a positive trend of 8 days per decade in the number of frost days during the rainy season.

Frost evolution in tailings

International Nuclear Information System (INIS)

1991-04-01

A review was carried out on the physical and thermal mechanisms of permafrost evaluation in soils and uranium tailings. The primary mechanism controlling permafrost evolution is conductive heat transfer with the latent heat of fusion of water being liberated as phase change occurs. Depending on the soil properties and freezing rate, pore water can be expelled from the frost front or pore water can migrate towards the frost front. Solute redistribution may occur as the frost front penetrates into the soil. The rate of frost penetration is a function of the thermal properties of the tailings and the climatic conditions. Computer modelling programmes capable of modelling permafrost evolution were reviewed. The GEOTHERM programme was selected as being the most appropriate for this study. The GEOTHERM programme uses the finite element method of thermal analysis. The ground surface temperature is determined by solving the energy balance equations a the ground surface. The GEOTHERM programme was used to simulate the permafrost evolution in the Key Lake Mine tailings located in north central Saskatchewan. The analyses indicated that the existing frozen zones in the tailing pond will eventually thaw if an average snow depth covers the tailings. Hundreds of years are required to thaw the tailings. If minimal snow cover is present the extent of the frozen zone in the tailings will increase

Current and emerging screening methods to identify post-head-emergence frost adaptation in wheat and barley.

Science.gov (United States)

Frederiks, T M; Christopher, J T; Harvey, G L; Sutherland, M W; Borrell, A K

2012-09-01

Cereal crops can suffer substantial damage if frosts occur at heading. Identification of post-head-emergence frost (PHEF) resistance in cereals poses a number of unique and difficult challenges. Many decades of research have failed to identify genotypes with PHEF resistance that could offer economically significant benefit to growers. Research and breeding gains have been limited by the available screening systems. Using traditional frost screening systems, genotypes that escape frost injury in trials due to spatial temperature differences and/or small differences in phenology can be misidentified as resistant. We believe that by improving techniques to minimize frost escapes, such 'false-positive' results can be confidently identified and eliminated. Artificial freezing chambers or manipulated natural frost treatments offer many potential advantages but are not yet at the stage where they can be reliably used for frost screening in breeding programmes. Here we describe the development of a novel photoperiod gradient method (PGM) that facilitates screening of genotypes of different phenology under natural field frosts at matched developmental stages. By identifying frost escapes and increasing the efficiency of field screening, the PGM ensures that research effort can be focused on finding genotypes with improved PHEF resistance. To maximize the likelihood of identifying PHEF resistance, we propose that the PGM form part of an integrated strategy to (i) source germplasm;(ii) facilitate high throughput screening; and (iii) permit detailed validation. PGM may also be useful in other studies where either a range of developmental stages and/or synchronized development are desired.

The periglacial engine of mountain erosion – Part 1: Rates of frost cracking and frost creep

Directory of Open Access Journals (Sweden)

J. L. Andersen

2015-10-01

Full Text Available With accelerating climate cooling in the late Cenozoic, glacial and periglacial erosion became more widespread on the surface of the Earth. The resultant shift in erosion patterns significantly changed the large-scale morphology of many mountain ranges worldwide. Whereas the glacial fingerprint is easily distinguished by its characteristic fjords and U-shaped valleys, the periglacial fingerprint is more subtle but potentially prevails in some mid- to high-latitude landscapes. Previous models have advocated a frost-driven control on debris production at steep headwalls and glacial valley sides. Here we investigate the important role that periglacial processes also play in less steep parts of mountain landscapes. Understanding the influences of frost-driven processes in low-relief areas requires a focus on the consequences of an accreting soil mantle, which characterises such surfaces. We present a new model that quantifies two key physical processes: frost cracking and frost creep, as a function of both temperature and sediment thickness. Our results yield new insights into how climate and sediment transport properties combine to scale the intensity of periglacial processes. The thickness of the soil mantle strongly modulates the relation between climate and the intensity of mechanical weathering and sediment flux. Our results also point to an offset between the conditions that promote frost cracking and those that promote frost creep, indicating that a stable climate can provide optimal conditions for only one of those processes at a time. Finally, quantifying these relations also opens up the possibility of including periglacial processes in large-scale, long-term landscape evolution models, as demonstrated in a companion paper.

Application of divertor cryopumping to H-mode density control in DIII-D

International Nuclear Information System (INIS)

Mahdavi, M.A.; Ferron, J.R.; Hyatt, A.W.

1993-11-01

In this paper we describe the method and the results of experiments where a unique in-vessel cryopump-baffle system was used to control density of H-mode plasmas. We were able to independently regulate current and density of ELMing H-mode plasmas, each over a range of factor two, and measure the H-mode confinement scaling with plasma density and current. With a modest pumping speed of ∼40 kl/s, particle exhaust rates as high as 2 x 10 22 atom/s -1 have been observed

Exploring new alleles for frost tolerance in winter rye.

Science.gov (United States)

Erath, Wiltrud; Bauer, Eva; Fowler, D Brian; Gordillo, Andres; Korzun, Viktor; Ponomareva, Mira; Schmidt, Malthe; Schmiedchen, Brigitta; Wilde, Peer; Schön, Chris-Carolin

2017-10-01

Rye genetic resources provide a valuable source of new alleles for the improvement of frost tolerance in rye breeding programs. Frost tolerance is a must-have trait for winter cereal production in northern and continental cropping areas. Genetic resources should harbor promising alleles for the improvement of frost tolerance of winter rye elite lines. For frost tolerance breeding, the identification of quantitative trait loci (QTL) and the choice of optimum genome-based selection methods are essential. We identified genomic regions involved in frost tolerance of winter rye by QTL mapping in a biparental population derived from a highly frost tolerant selection from the Canadian cultivar Puma and the European elite line Lo157. Lines per se and their testcrosses were phenotyped in a controlled freeze test and in multi-location field trials in Russia and Canada. Three QTL on chromosomes 4R, 5R, and 7R were consistently detected across environments. The QTL on 5R is congruent with the genomic region harboring the Frost resistance locus 2 (Fr-2) in Triticeae. The Puma allele at the Fr-R2 locus was found to significantly increase frost tolerance. A comparison of predictive ability obtained from the QTL-based model with different whole-genome prediction models revealed that besides a few large, also small QTL effects contribute to the genomic variance of frost tolerance in rye. Genomic prediction models assigning a high weight to the Fr-R2 locus allow increasing the selection intensity for frost tolerance by genome-based pre-selection of promising candidates.

Liquid Argon Calorimetry with LHC-Performance Specifications

CERN Multimedia

2002-01-01

% RD-3 Liquid Argon Calorimetry with LHC-Performance Specifications \\\\ \\\\Good electromagnetic and hadronic calorimetry will play a central role in an LHC detector. Among the techniques used so far, or under development, the liquid argon sampling calorimetry offers high radiation resistence, good energy resolution (electromagnetic and hadronic), excellent calibration stability and response uniformity. Its rate capabilities, however, do not yet match the requirements for LHC. \\\\ \\\\The aim of this proposal is to improve the technique in such a way that high granularity, good hermiticity and adequate rate capabilities are obtained, without compromising the above mentioned properties. To reach this goal, we propose to use a novel structure, the $^{\\prime\\prime}$accordion$^{\\prime\\prime}$, coupled to fast preamplifiers working at liquid argon temperature. Converter and readout electrodes are no longer planar and perpendicular to particles, as usual, but instead they are wiggled around a plane containing particles. ...

Test facility TIMO for testing the ITER model cryopump

International Nuclear Information System (INIS)

Haas, H.; Day, C.; Mack, A.; Methe, S.; Boissin, J.C.; Schummer, P.; Murdoch, D.K.

2001-01-01

Within the framework of the European Fusion Technology Programme, FZK is involved in the research and development process for a vacuum pump system of a future fusion reactor. As a result of these activities, the concept and the necessary requirements for the primary vacuum system of the ITER fusion reactor were defined. Continuing that development process, FZK has been preparing the test facility TIMO (Test facility for ITER Model pump) since 1996. This test facility provides for testing a cryopump all needed infrastructure as for example a process gas supply including a metering system, a test vessel, the cryogenic supply for the different temperature levels and a gas analysing system. For manufacturing the ITER model pump an order was given to the company L' Air Liquide in the form of a NET contract. (author)

Test facility TIMO for testing the ITER model cryopump

International Nuclear Information System (INIS)

Haas, H.; Day, C.; Mack, A.; Methe, S.; Boissin, J.C.; Schummer, P.; Murdoch, D.K.

1999-01-01

Within the framework of the European Fusion Technology Programme, FZK is involved in the research and development process for a vacuum pump system of a future fusion reactor. As a result of these activities, the concept and the necessary requirements for the primary vacuum system of the ITER fusion reactor were defined. Continuing that development process, FZK has been preparing the test facility TIMO (Test facility for ITER Model pump) since 1996. This test facility provides for testing a cryopump all needed infrastructure as for example a process gas supply including a metering system, a test vessel, the cryogenic supply for the different temperature levels and a gas analysing system. For manufacturing the ITER model pump an order was given to the company L'Air Liquide in the form of a NET contract. (author)

Condensation and frost formation in heat exchangers

International Nuclear Information System (INIS)

Rostami, A.A.

1982-01-01

The occurence of condensation and of frost formation are considered for air to heat exchangers with emphasis on how such occurrences would affect the performance of such heat exchangers when they are used in ventilating applications. The formulations which predict performance are developed for parallel, counter flow and cross flow with either formation or condensation, and for condensation the consequences for evaporation of condensate and of the effect of longitudinal conduction in the walls of the exchanger are also considered. For the prediction of the exchanger performance with frost formation there must be specified the growth of the frost layer with time and existing theories for this growth are examined, a new method of calculation of the growth is presented and this is shown to give results for the growth that are in accord with available experimental evidence. This new theory for the growth of a frost layer is used to predict the performance of a parallel flow exchanger under conditions in which frost formation occurs, by successively applying the steady state performance calculation for time increments over which the frost layer build-up is calculated for these time increments. The calculation of counter flow exchanger performance by this method, while feasible, is so time consuming that only the general aspects of the calculation are considered

Novel manufacturing method by using stainless steel pipes expanded into aluminium profiles for the ITER Neutral Beam cryopumps

Energy Technology Data Exchange (ETDEWEB)

Dremel, Matthias, E-mail: matthias.dremel@iter.org; Boissin, Jean-Claude; Déléage, Vincent; Quinn, Eamonn; Pearce, Robert

2015-10-15

This paper describes the novel engineering and manufacturing solution of stainless steel pipe expansion into aluminium extrusion profiles for use at cryogenic temperatures up to 400 K. This fabrication method will be used for the thermal radiation shields and the cryopanels of the ITER Neutral Beam cryopumps. The use of stainless steel pipes expanded into aluminium extrusion profiles is a solution that combines standard stainless steel welding procedures for the manifolds of the cooling circuits with extended aluminium structures taking advantage of the high thermal conductivity of aluminium. The cryogenic cooling circuits of the pump are a first confinement barrier in the ITER vacuum vessel and the risk of a leakage needs to be minimized as far as possible. The expansion method avoids the need of joints of dissimilar materials in the primary confinement barrier. The fabrication method and results of the prototyping of full scaled components for the ITER Neutral Beam cryopumps are outlined in this paper.

Delayed frost growth on jumping-drop superhydrophobic surfaces.

Science.gov (United States)

Boreyko, Jonathan B; Collier, C Patrick

2013-02-26

Self-propelled jumping drops are continuously removed from a condensing superhydrophobic surface to enable a micrometric steady-state drop size. Here, we report that subcooled condensate on a chilled superhydrophobic surface are able to repeatedly jump off the surface before heterogeneous ice nucleation occurs. Frost still forms on the superhydrophobic surface due to ice nucleation at neighboring edge defects, which eventually spreads over the entire surface via an interdrop frost wave. The growth of this interdrop frost front is shown to be up to 3 times slower on the superhydrophobic surface compared to a control hydrophobic surface, due to the jumping-drop effect dynamically minimizing the average drop size and surface coverage of the condensate. A simple scaling model is developed to relate the success and speed of interdrop ice bridging to the drop size distribution. While other reports of condensation frosting on superhydrophobic surfaces have focused exclusively on liquid-solid ice nucleation for isolated drops, these findings reveal that the growth of frost is an interdrop phenomenon that is strongly coupled to the wettability and drop size distribution of the surface. A jumping-drop superhydrophobic condenser minimized frost formation relative to a conventional dropwise condenser in two respects: preventing heterogeneous ice nucleation by continuously removing subcooled condensate, and delaying frost growth by limiting the success of interdrop ice bridge formation.

Study of Liquid Argon Dopants for LHC Hadron Calorimetry

CERN Multimedia

2002-01-01

Hadron calorimetry based on the Liquid Argon Ionisation Chamber technique is one of the choice techniques for LHC-experimentation. A systematic study of the effect of selected dopants on Liquid Argon (LAr) will be carried out with the aim to achieve an improvement on: \\item (i)~``Fast Liquid Argon'' search and study of dopants to increase the drift velocity. It has been already shown that CH&sub4. added at a fraction of one percent increases the drift velocity by a factor of two or more. \\item (ii)~``Compensated Liquid Argon'' search and study of dopants to increase the response to densely ionising particles, resulting in improved compensation, such as photosensitive dopants. \\end{enumerate}\\\\ \\\\ Monitoring of the parameters involved in understanding the response of a calorimeter is essential. In case of doped LAr, the charge yield, the non-saturated drift velocity and the electron lifetime in the liquid should be precisely and simultaneously monitored as they all vary with the level of dopant concentrati...

Frosting and defrosting of air-coils - results from laboratory testing

Energy Technology Data Exchange (ETDEWEB)

Fahlen, P

1997-12-31

Frosting of air-coils is an important factor in the design and operation of air-source heat pumps, heat recovery ventilators, cooling and refrigeration equipment etc. This report presents results from laboratory testing of two brine-cooled air-coils under frosting conditions. The coils have the same number of plane, continuous fins, 4 tube rows with 12 tubes in each row, tube spacing of 50 mm and fin spacing of 3 and 6 mm respectively. The original purpose of the test program was to compare various possible indicators of coil frosting and to analyze the possible effects of different control strategies on coil capacity and the COP of the system (the analysis will be presented in a separate report). Tests involved inlet air temperatures of -7 and +2 degC, variation of humidity between 70 and 100% RH (including simulated rain), velocities in the range 1 to 4 m/s, and specific cooling loads from 50 to 150 W/m{sup 2}. Test results include variations due to frosting of e.g. cooling capacity, COP, air flow and pressure drop, fan power, air outlet temperature and humidity, coil temperature, frost mass, and frosting time. Results also include the subsequently required defrost time, defrost energy and collected mass of defrost water. The frosting process was interrupted when the air flow had decreased to 30% of the original value with a non-frosted coil. The results clearly show the advantage of demand controlled defrosting with variations in frosting time between 2 h with high humidity/high specific cooling load up to, for practical purposes, infinite frosting times with low humidity/low specific cooling load. The accumulated frost mass during one frosting cycle varied from less than 0.02 kg/m{sup 2} up to approximately 0.4 kg/m{sup 2}. 23 refs, 93 figs, 89 tabs

Frosting and defrosting of air-coils - results from laboratory testing

Energy Technology Data Exchange (ETDEWEB)

Fahlen, P.

1996-12-31

Frosting of air-coils is an important factor in the design and operation of air-source heat pumps, heat recovery ventilators, cooling and refrigeration equipment etc. This report presents results from laboratory testing of two brine-cooled air-coils under frosting conditions. The coils have the same number of plane, continuous fins, 4 tube rows with 12 tubes in each row, tube spacing of 50 mm and fin spacing of 3 and 6 mm respectively. The original purpose of the test program was to compare various possible indicators of coil frosting and to analyze the possible effects of different control strategies on coil capacity and the COP of the system (the analysis will be presented in a separate report). Tests involved inlet air temperatures of -7 and +2 degC, variation of humidity between 70 and 100% RH (including simulated rain), velocities in the range 1 to 4 m/s, and specific cooling loads from 50 to 150 W/m{sup 2}. Test results include variations due to frosting of e.g. cooling capacity, COP, air flow and pressure drop, fan power, air outlet temperature and humidity, coil temperature, frost mass, and frosting time. Results also include the subsequently required defrost time, defrost energy and collected mass of defrost water. The frosting process was interrupted when the air flow had decreased to 30% of the original value with a non-frosted coil. The results clearly show the advantage of demand controlled defrosting with variations in frosting time between 2 h with high humidity/high specific cooling load up to, for practical purposes, infinite frosting times with low humidity/low specific cooling load. The accumulated frost mass during one frosting cycle varied from less than 0.02 kg/m{sup 2} up to approximately 0.4 kg/m{sup 2}. 23 refs, 93 figs, 89 tabs

Effect of variations in air speed on cross-flow cylinder frosting

International Nuclear Information System (INIS)

Monaghan, P.F.; Cassidy, S.F.; Oosthuizen, P.H.

1990-01-01

In this paper the effect of fluctuating air speed on frost growth and heat transfer to a cylinder in cross-flow is discussed. Frost-growth of up to 20 hours is simulated using an experimentally validated finite difference computer model. Graphical results are presented for frost mass, frost depth, frost surface temperature and heat transfer versus time under both steady and fluctuating air speed conditions. In general, it is found that a thinner, more dense frost layer develops under fluctuating air speed conditions giving improved heat transfer. This phenomenon may be explained by the increased frequency of frost surface thaw/freeze cycles when fluctuating air speed conditions prevail

Effect of frost on phosphorescence for thermographic phosphor thermometry

Science.gov (United States)

Kim, Dong; Kim, Mirae; Kim, Kyung Chun

2017-12-01

In this study, we analyzed phosphorescence lifetime and its accuracy by growing frost for thermographic phosphor thermometry in a low-temperature environment. Mg4FGeO6:Mn particles were coated on an aluminum plate and excited with a UV-LED to obtain phosphorescence signals. The surface temperature was maintained at  -20, -15, -10 °C, and the phosphorescence signal was acquired as the frost grew for 3700 s. The lifetime was calculated and compared with the calibration curve under no-frost conditions. The error of the measured lifetime was within 0.7% of that in the no-frost conditions. A 2D surface temperature profile of the target plate was successfully obtained with the frost formation.

Self-jumping Mechanism of Melting Frost on Superhydrophobic Surfaces.

Science.gov (United States)

Liu, Xiaolin; Chen, Huawei; Zhao, Zehui; Wang, Yamei; Liu, Hong; Zhang, Deyuan

2017-11-07

Frost accretion on surfaces may cause severe problems and the high-efficiency defrosting methods are still urgently needed in many application fields like heat transfer, optical and electric power system, etc. In this study, a nano-needle superhydrophobic surface is prepared and the frosting/defrosting experiments are conducted on it. Three steps are found in the defrosting process: melting frost shrinking and splitting, instantaneous self-triggered deforming followed by deformation-induced movements (namely, in-situ shaking, rotating, rolling, and self-jumping). The self-jumping performance of the melting frost is extremely fascinating and worth studying due to its capability of evidently shortening the defrosting process and reducing (even avoiding) residual droplets after defrosting. The study on the melting frost self-jumping phenomena demonstrates that the kinetic energy transformed from instantaneous superficial area change in self-triggered deforming step is the intrinsic reason for various melting frost self-propelled movements, and when the transformed energy reaches a certain amount, the self-jumping phenomena occur. And some facilitating conditions for melting frost self-jumping phenomena are also discussed. This work will provide an efficient way for defrosting or an inspiration for further research on defrosting.

Frost monitoring of fruit tree with satellite data

Science.gov (United States)

Fan, Jinlong; Zhang, Mingwei; Cao, Guangzheng; Zhang, Xiaoyu; Liu, Chenchen; Niu, Xinzan; Xu, Wengbo

2012-09-01

The orchards are developing very fast in the northern China in recent years with the increasing demands on fruits in China. In most parts of the northern China, the risk of frost damage to fruit tree in early spring is potentially high under the background of global warming. The growing season comes earlier than it does in normal year due to the warm weather in earlier spring and the risk will be higher in this case. According to the reports, frost event in spring happens almost every year in Ningxia Region, China. In bad cases, late frosts in spring can be devastating all fruit. So lots of attention has been given to the study in monitoring, evaluating, preventing and mitigating frost. Two orchards in Ningxia, Taole and Jiaozishan orchards were selected as the study areas. MODIS data were used to monitor frost events in combination with minimum air temperature recorded at weather station. The paper presents the findings. The very good correlation was found between MODIS LST and minimum air temperature in Ningxia. Light, middle and severe frosts were captured in the study area by MODIS LST. The MODIS LST shows the spatial differences of temperature in the orchards. 10 frost events in April from 2000 to 2010 were captured by the satellite data. The monitoring information may be hours ahead circulated to the fruit farmers to prevent the damage and loss of fruit trees.

Steady-state exhaust of helium ash in the W-shaped divertor of JT-60U

International Nuclear Information System (INIS)

Sakasai, A.; Takenaga, H.; Hosogane, N.

2001-01-01

By injecting a neutral beam of 60 keV helium (He) atoms as central fueling of helium into the ELMy H-mode plasmas, helium exhaust has been studied in the W-shaped pumped divertor on JT-60U. Efficient He exhaust was realized by He pumping using argon frosted cryopumps in the JT-60U new divertor. In steady state, good He exhaust capability (τ He */τ E =4 and high enrichment factor, where τ He * is a global particle confinement time of helium and τ E is the energy confinement time) was successfully demonstrated in attached ELMy H-mode plasmas. Good He exhaust capability was also obtained in detached ELMy H-mode plasmas, which was comparable to one in attached plasmas. This result of the helium exhaust is sufficient to support a detached divertor operation on ITER. After the divertor modification, helium exhaust in reversed shear plasmas has been investigated using He gas puff. Helium removal inside the internal transport barrier (ITB) is about two times as difficult as that outside the ITB in reversed shear discharges. (author)

Research on curing behavior of concrete with anti-frost admixtures at subzero temperature

Science.gov (United States)

Ionov, Yulian; Kramar, Ludmila; Kirsanova, Alena; Kolegova, Irina

2017-01-01

The purpose of this paper is research on curing behavior of cold-weather concrete with anti-frost admixtures. During the study derivative thermal and X-ray phase analyses were performed and tests were carried out according to the standard GOST technique. The research results obtained reveal the peculiarities of cement hydration and concrete curing at subzero temperatures. The influence of subzero temperatures and anti-frost admixtures on hydrated phases of hardened cement paste and concrete strength formation was studied. It is found that cold-weather concrete does not cure at subzero temperatures, but when defrosting it attains 80 to 85% of its grade strength by the 28th day. Concrete achieves its grade strength when curing in normal conditions in 60 days only. Freezing concrete with anti-frost admixtures results in increase of calcium hydroxide content in hardened cement paste immediately when produced and has increased tendency of concrete to carbonation.

Systematic vacuum study of the ITER model cryopump by test particle Monte Carlo simulation

Energy Technology Data Exchange (ETDEWEB)

Luo, Xueli; Haas, Horst; Day, Christian [Institute for Technical Physics, Karlsruhe Institute of Technology, P.O. Box 3640, 76021 Karlsruhe (Germany)

2011-07-01

The primary pumping systems on the ITER torus are based on eight tailor-made cryogenic pumps because not any standard commercial vacuum pump can meet the ITER working criteria. This kind of cryopump can provide high pumping speed, especially for light gases, by the cryosorption on activated charcoal at 4.5 K. In this paper we will present the systematic Monte Carlo simulation results of the model pump in a reduced scale by ProVac3D, a new Test Particle Monte Carlo simulation program developed by KIT. The simulation model has included the most important mechanical structures such as sixteen cryogenic panels working at 4.5 K, the 80 K radiation shield envelope with baffles, the pump housing, inlet valve and the TIMO (Test facility for the ITER Model Pump) test facility. Three typical gas species, i.e., deuterium, protium and helium are simulated. The pumping characteristics have been obtained. The result is in good agreement with the experiment data up to the gas throughput of 1000 sccm, which marks the limit for free molecular flow. This means that ProVac3D is a useful tool in the design of the prototype cryopump of ITER. Meanwhile, the capture factors at different critical positions are calculated. They can be used as the important input parameters for a follow-up Direct Simulation Monte Carlo (DSMC) simulation for higher gas throughput.

Correlation of Water Frost Porosity in Laminar Flow over Flat Surfaces

Science.gov (United States)

Kandula, Max

2011-01-01

A dimensionless correlation has been proposed for water frost porosity expressing its dependence on frost surface temperature and Reynolds number for laminar forced flow over a flat surface. The correlation is presented in terms of a dimensionless frost surface temperature scaled with the cold plate temperature, and the freezing temperature. The flow Reynolds number is scaled with reference to the critical Reynolds number for laminar-turbulent transition. The proposed correlation agrees satisfactorily with the simultaneous measurements of frost density and frost surface temperature covering a range of plate temperature, ambient air velocity, humidity, and temperature. It is revealed that the frost porosity depends primarily on the frost surface and the plate temperatures and the flow Reynolds number, and is only weakly dependent on the relative humidity. The results also point out the general character of frost porosity displaying a decrease with an increase in flow Reynolds number.

Frost damage of concrete subject to confinement

DEFF Research Database (Denmark)

Hasholt, Marianne Tange

2016-01-01

When internal frost damage is observed in real concrete structures, the usual pattern is cracks with a preferred orientation parallel to the exposed surface. When exposing concrete with poor frost resistance to a standardised freeze/thaw test in the laboratory, the orientations of the resulting...

Frost hardiness of tree species is independent of phenology and macroclimatic niche.

Science.gov (United States)

Hofmann, M; Bruelheide, H

2015-03-01

The differences in timing in bud burst between species have been interpreted as an adaptation to late frost events in spring. Thus, it has been suggested that the degree of frost susceptibility of leaves is species-specific and depends on the species' phenology and geographic distribution range. To test for relationships between frost tolerance and phenology as well as between frost tolerance and distribution range across Central European tree species, we studied the frost hardiness of closed buds before bud burst and of freshly opened buds at the time of bud burst. We hypothesized that species with early bud burst and species distributed in eastern and northern areas were more frost tolerant than species with late bud burst and species distributed in western and southern areas. Frost hardiness was estimated by exposing twigs to 11 frost temperatures between -4 °C and -80 °C and by assessing tissue damage by the electrolyte leakage method. In contrast to our hypotheses, neither frost hardiness of closed buds nor frost hardiness of freshly opened buds were related to any variable describing species' macroclimatic niche. Furthermore, frost hardiness of freshly opened buds did not differ among species. Thus, the investigated species with early bud burst take higher risks of frost damage than the species with late bud bursts. These findings indicate that frost hardiness might not play the key role in limiting the geographic distribution ranges previously anticipated.

Anti-icing/frosting and self-cleaning performance of superhydrophobic aluminum alloys

Science.gov (United States)

Feng, Libang; Yan, Zhongna; Shi, Xueting; Sultonzoda, Firdavs

2018-02-01

Ice formation and frost deposition on cryogenic equipment and systems can result in serious problems and huge economic loss. Hence, it is quite necessary to develop new materials to prevent icing and frosting on cold surfaces in engineering fields. Here, a superhydrophobic aluminum alloy with enhanced anti-frosting, anti-icing, and self-cleaning performance has been developed by a facile one-step method. The anti-frosting/icing performance of superhydrophobic aluminum alloys is confirmed by frosting/icing time delay, consolidating and freezing temperature reduction, and lower amount of frost/ice adhesion. Meanwhile, the excellent self-cleaning performance is authenticated by the fact that simulated pollution particles can be cleaned out by rolling water droplets completely. Finally, based on the classical nucleation theory, anti-icing and anti-frosting mechanisms of the superhydrophobic aluminum alloys are deduced. Results show that grounded on "air cushion" and "heat insulation" effect, a larger nucleation barrier and a lower crystal growth rate can be observed, which, hence, inhibit ice formation and frost deposition. It can be concluded that preparing superhydrophobic surfaces would be an effective strategy for improving anti-icing, anti-frosting, and self-cleaning performance of aluminum alloys.

Polygons in Seasonal Frost

Science.gov (United States)

2004-01-01

8 February 2004 This Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC) image shows a summertime scene in the south polar region of the red planet. A patch of bright frost--possibly water ice--is seen in the lower third of the image. Polygon patterns that have developed in the ice as it sublimes away can be seen; these are not evident in the defrosted surfaces, so they are thought to have formed in the frost. This image is located near 82.6oS, 352.5oW. Sunlight illuminates this scene from the upper left; the image covers an area 3 km (1.9 mi) wide.

Morphological and genetic perspectives of peach fruit responses to spring frost

Science.gov (United States)

Spring frost is one of the most unpredictable cropping factors in many peach production areas. A severe spring frost can wipe out an entire peach crop whereas a mild spring frost may naturally help thinning as is common practice in commercial peach production. The extent of frost damage depends on t...

Uremic frost: a harbinger of impending renal failure.

Science.gov (United States)

Saardi, Karl M; Schwartz, Robert A

2016-01-01

Uremic frost is a striking cutaneous finding seen in patients with severe kidney disease. Familiarity with this condition can be a life-saving signal to initiate urgent dialysis. Uremic frost generally occurs at blood urea nitrogen levels of approximately 200 mg/dl, although it may arise with less severe uremia. Recently confirmed urea transporters in the skin may play a role in the development of uremic frost. Alternatively, damage to the cutaneous microvasculature and pilosebaceous units, as seen in chronic kidney disease, could account for the high levels of urea deposited outside the skin. The treatment of uremic frost is largely aimed at correcting the underlying cause of uremia and the other life-threatening conditions associated with renal failure. © 2015 The International Society of Dermatology.

Frost trends and their estimated impact on yield in the Australian wheatbelt.

Science.gov (United States)

Zheng, Bangyou; Chapman, Scott C; Christopher, Jack T; Frederiks, Troy M; Chenu, Karine

2015-06-01

Radiant spring frosts occurring during reproductive developmental stages can result in catastrophic yield loss for wheat producers. To better understand the spatial and temporal variability of frost, the occurrence and impact of frost events on rain-fed wheat production was estimated across the Australian wheatbelt for 1957-2013 using a 0.05 ° gridded weather data set. Simulated yield outcomes at 60 key locations were compared with those for virtual genotypes with different levels of frost tolerance. Over the last six decades, more frost events, later last frost day, and a significant increase in frost impact on yield were found in certain regions of the Australian wheatbelt, in particular in the South-East and West. Increasing trends in frost-related yield losses were simulated in regions where no significant trend of frost occurrence was observed, due to higher mean temperatures accelerating crop development and causing sensitive post-heading stages to occur earlier, during the frost risk period. Simulations indicated that with frost-tolerant lines the mean national yield could be improved by up to 20% through (i) reduced frost damage (~10% improvement) and (ii) the ability to use earlier sowing dates (adding a further 10% improvement). In the simulations, genotypes with an improved frost tolerance to temperatures 1 °C lower than the current 0 °C reference provided substantial benefit in most cropping regions, while greater tolerance (to 3 °C lower temperatures) brought further benefits in the East. The results indicate that breeding for improved reproductive frost tolerance should remain a priority for the Australian wheat industry, despite warming climates. © The Author 2015. Published by Oxford University Press on behalf of the Society for Experimental Biology.

Coupling of THALES and FROST using MPI Method

International Nuclear Information System (INIS)

Park, Jin Woo; Ryu, Seok Hee; Jung, Chan Do; Jung, Jee Hoon; Um, Kil Sup; Lee, Jae Il

2013-01-01

This paper presents the coupling method between THALES and FROST and the simulation results with the coupled code system. In this study, subchannel analysis code THALES and transient fuel performance code FROST were coupled using MPI method as the first stage of the development of the multi-dimensional safety analysis methodology. As a part of the validation, the CEA ejection accident was simulated using the coupled THALES-FROST code and the results were compared with the ShinKori 3 and 4 FSAR. Comparison results revealed that CHASER using MPI method predicts fuel temperatures and heat flux quantitatively well. Thus it was confirmed that the THALES and FROST are properly coupled. In near future, ASTRA, multi-dimensional core neutron kinetics code, will be linked to THALESFROST code for the detailed three-dimensional CEA ejection analysis. The current safety analysis methodology for a CEA ejection accident based on numerous conservative assumptions with the point kinetics model results in quite adverse consequences. Thus, KNF is developing the multi-dimensional safety analysis methodology to enhance the consequences of the CEA ejection accident. For this purpose, three-dimensional core neutron kinetics code ASTRA, subchannel analysis code THALES, and transient fuel performance analysis code FROST are being coupled using message passing interface(MPI). For the first step, THALES and FROST are coupled and tested

SO2 frost - UV-visible reflectivity and Io surface coverage

Science.gov (United States)

Nash, D. B.; Fanale, F. P.; Nelson, R. M.

1980-01-01

The reflectance spectrum in the range 0.24-0.85 microns of SO2 frost is measured in light of the discovery of SO2 gas in the atmosphere of Io and the possible discovery of the frost on its surface. Frost deposits up to 1.5 mm thick were grown in vacuum at 130 K and bi-directional reflectance spectra were obtained. Typical SO2 frost is found to exhibit very low reflectivity (2-5%) at 0.30 microns, rising steeply at 0.32 microns to attain a maximum reflectivity (75-80%) at 4.0 microns and uniformly high reflectivity throughout the visible and near infrared. Comparison with the full disk spectrum of Io reveals that no more than 20% of the surface can be covered with optically thick SO2 frost. Combinations of surface materials including SO2 frost which can produce the observed spectrum are indicated.

Frost heave susceptibility of saturated soil under constant rate of freezing

Science.gov (United States)

Ryokai, K.; Iguro, M.; Yoneyama, K.

Introduced are the results of experiments carried out to quantitatively obtain the frost heave pressure and displacement of soil subjected to artificial freezing or freezing around in-ground liquefied natural gas storage tanks. This experiment is conducted to evaluate the frost heave susceptibility of saturated soil under overconsolidation. In other words, this experiment was carried out to obtain the relation of the over-burden pressure and freezing rate to the frost heave ratio by observing the frost heave displacement and freezing time of specimens by freezing the specimens at a constant freezing rate under a constant overburden pressure, while letting water freely flow in and out of the system. Introduced are the procedures for frost heave test required to quantitatively obtain the frost heave displacement and pressure of soil. Furthermore, the relation between the frost heave susceptibility and physical properties of soil obtained by this test is reported.

Argon activation analysis, application to dating by the potassium-argon method; Analyse par activation de l'argon. Application a la datation par la methode potassium-argon

Energy Technology Data Exchange (ETDEWEB)

Dumesnil, P [Commissariat a l' Energie Atomique, Saclay (France). Centre d' Etudes Nucleaires

1967-07-01

Activation analysis using radiogenic argon-40 has been applied to rock-dating by the K-Ar method. The argon is extracted from the sample, purified, activated to saturation in a flux of 2 X 10{sup 13} neutrons/cm{sup 2} sec{sup -1} and measured by gamma spectroscopy. The sensitivity obtained is such that it is possible to measure amounts of argon corresponding to age of a few thousand years only. However since it has not been possible to measure the amount of pollution of radiogenic argon by atmospheric argon with any accuracy, the measurable age limit is in fact of the order of MY. The method has been applied to basalts from the Mont-Dore region. The results obtained are in fairly good agreement with geological, stratigraphic and paleomagnetic data. (author) [French] L'analyse par activation de l'argon 40 radiogenique a ete appliquee a la datation des roches par la methode K-Ar. L'argon est extrait de l'echantillon, purifie, active a saturation dans un flux de 2.10{sup 13} neutrons.cm{sup -2}.s{sup -1} et mesure en spectrometrie gamma. La sensibilite obtenue est telle qu'il est possible de mesurer des quantites d'argon correspondant a des ages de quelques milliers d'annees seulement. Cependant la correction de pollution de l'argon radiogenique par l'argon atmospherique n'ayant pu etre etablie avec precision, la limite d'age mesurable pratique est de l'ordre de 1 Ma. La methode a ete appliquee aux basaltes de la region du Mont-Dore. Les ages obtenus sont en assez bon accord avec les donnees geologiques, stratigraphiques et paleomagnetiques. (auteur)

Frost resistance of fibre reinforced concrete structures

DEFF Research Database (Denmark)

Hansen, Ernst Jan De Place

1999-01-01

Frost resistance of fibre reinforced concrete with 2.5-4.2% air and 6-9% air (% by volume in fresh concrete) casted in the laboratory and in-situ is compared. Steel fibres with hooked ends (ZP, length 30 mm) and polypropylene fibres (PP, CS, length 12 mm) are applied. It is shown that· addition...... of 0.4-1% by volume of fibres cannot replace air entrainment in order to secure a frost resistant concrete; the minimum amount of air needed to make the concrete frost resistant is not changed when adding fibres· the amount of air entrainment must be increased when fibres are added to establish...

Spring frost vulnerability of sweet cherries under controlled conditions.

Science.gov (United States)

Matzneller, Philipp; Götz, Klaus-P; Chmielewski, Frank-M

2016-01-01

Spring frost is a significant production hazard in nearly all temperate fruit-growing regions. Sweet cherries are among the first fruit varieties starting their development in spring and therefore highly susceptible to late frost. Temperatures at which injuries are likely to occur are widely published, but their origin and determination methods are not well documented. In this study, a standardized method was used to investigate critical frost temperatures for the sweet cherry cultivar 'Summit' under controlled conditions. Twigs were sampled at four development stages ("side green," "green tip," "open cluster," "full bloom") and subjected to three frost temperatures (-2.5, -5.0, -10.0 °C). The main advantage of this method, compared to other approaches, was that the exposition period and the time interval required to reach the target temperature were always constant (2 h). Furthermore, then, the twigs were placed in a climate chamber until full bloom, before the examination of the flowers and not further developed buds started. For the first two sampling stages (side green, green tip), the number of buds found in open cluster, "first white," and full bloom at the evaluation date decreased with the strength of the frost treatment. The flower organs showed different levels of cold hardiness and became more vulnerable in more advanced development stages. In this paper, we developed four empirical functions which allow calculating possible frost damages on sweet cherry buds or flowers at the investigated development stages. These equations can help farmers to estimate possible frost damages on cherry buds due to frost events. However, it is necessary to validate the critical temperatures obtained in laboratory with some field observations.

Spring frost vulnerability of sweet cherries under controlled conditions

Science.gov (United States)

Matzneller, Philipp; Götz, Klaus-P.; Chmielewski, Frank-M.

2016-01-01

Spring frost is a significant production hazard in nearly all temperate fruit-growing regions. Sweet cherries are among the first fruit varieties starting their development in spring and therefore highly susceptible to late frost. Temperatures at which injuries are likely to occur are widely published, but their origin and determination methods are not well documented. In this study, a standardized method was used to investigate critical frost temperatures for the sweet cherry cultivar `Summit' under controlled conditions. Twigs were sampled at four development stages ("side green," "green tip," "open cluster," "full bloom") and subjected to three frost temperatures (-2.5, -5.0, -10.0 °C). The main advantage of this method, compared to other approaches, was that the exposition period and the time interval required to reach the target temperature were always constant (2 h). Furthermore, then, the twigs were placed in a climate chamber until full bloom, before the examination of the flowers and not further developed buds started. For the first two sampling stages (side green, green tip), the number of buds found in open cluster, "first white," and full bloom at the evaluation date decreased with the strength of the frost treatment. The flower organs showed different levels of cold hardiness and became more vulnerable in more advanced development stages. In this paper, we developed four empirical functions which allow calculating possible frost damages on sweet cherry buds or flowers at the investigated development stages. These equations can help farmers to estimate possible frost damages on cherry buds due to frost events. However, it is necessary to validate the critical temperatures obtained in laboratory with some field observations.

Frost-covered dunes

Science.gov (United States)

1999-01-01

MOC image of dunes in Chasma Boreale, a giant trough in the north polar cap. This September 1998 view shows dark sand emergent from beneath a veneer of bright frost left over from the northern winter that ended in July 1998.

Frost in Charitum Montes

Science.gov (United States)

2003-01-01

MGS MOC Release No. MOC2-387, 10 June 2003This is a Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC) wide angle view of the Charitum Montes, south of Argyre Planitia, in early June 2003. The seasonal south polar frost cap, composed of carbon dioxide, has been retreating southward through this area since spring began a month ago. The bright features toward the bottom of this picture are surfaces covered by frost. The picture is located near 57oS, 43oW. North is at the top, south is at the bottom. Sunlight illuminates the scene from the upper left. The area shown is about 217 km (135 miles) wide.

The ATLAS Liquid Argon Calorimeter: Construction, Integration, Commissioning

International Nuclear Information System (INIS)

Aleksa, Martin

2006-01-01

The ATLAS liquid argon (LAr) calorimeter system consists of an electromagnetic barrel calorimeter and two end caps with electromagnetic, hadronic and forward calorimeters. The liquid argon sampling technique, with an accordion geometry was chosen for the barrel electromagnetic calorimeter (EMB) and adapted to the end cap (EMEC). The hadronic end cap calorimeter (HEC) uses a copper-liquid argon sampling technique with flat plate geometry and is subdivided in depth in two wheels per end-cap. Finally, the forward calorimeter (FCAL) is composed of three modules employing cylindrical electrodes with thin liquid argon gaps.The construction of the full calorimeter system is complete since mid-2004. Production modules constructed in the home institutes were integrated into wheels at CERN in 2003-2004, and inserted into the three cryostats. They passed their first complete cold test before the lowering into the ATLAS cavern. Results of quality checks (e.g. electrical, mechanical, ...) performed on all the 190304 read-out channels after cool down will be reported. End 2004 the ATLAS barrel electromagnetic (EM) calorimeter was installed in the ATLAS cavern and since summer 2005 the front-end electronics are being connected and tested. Results of this first commissioning phase will be shown to demonstrate the high standards of quality control for our detectors

Forecast of Frost Days Based on Monthly Temperatures

Science.gov (United States)

Castellanos, M. T.; Tarquis, A. M.; Morató, M. C.; Saa-Requejo, A.

2009-04-01

Although frost can cause considerable crop damage and mitigation practices against forecasted frost exist, frost forecasting technologies have not changed for many years. The paper reports a new method to forecast the monthly number of frost days (FD) for several meteorological stations at Community of Madrid (Spain) based on successive application of two models. The first one is a stochastic model, autoregressive integrated moving average (ARIMA), that forecasts monthly minimum absolute temperature (tmin) and monthly average of minimum temperature (tminav) following Box-Jenkins methodology. The second model relates these monthly temperatures to minimum daily temperature distribution during one month. Three ARIMA models were identified for the time series analyzed with a stational period correspondent to one year. They present the same stational behavior (moving average differenced model) and different non-stational part: autoregressive model (Model 1), moving average differenced model (Model 2) and autoregressive and moving average model (Model 3). At the same time, the results point out that minimum daily temperature (tdmin), for the meteorological stations studied, followed a normal distribution each month with a very similar standard deviation through years. This standard deviation obtained for each station and each month could be used as a risk index for cold months. The application of Model 1 to predict minimum monthly temperatures showed the best FD forecast. This procedure provides a tool for crop managers and crop insurance companies to asses the risk of frost frequency and intensity, so that they can take steps to mitigate against frost damage and estimated the damage that frost would cost. This research was supported by Comunidad de Madrid Research Project 076/92. The cooperation of the Spanish National Meteorological Institute and the Spanish Ministerio de Agricultura, Pesca y Alimentation (MAPA) is gratefully acknowledged.

Passive anti-frosting surfaces using microscopic ice arrays

Science.gov (United States)

Ahmadi, Farzad; Nath, Saurabh; Iliff, Grady; Boreyko, Jonathan

2017-11-01

Despite exceptional advances in surface chemistry and micro/nanofabrication, no engineered surface has been able to passively suppress the in-plane growth of frost occurring in humid, subfreezing environments. Motivated by this, and inspired by the fact that ice itself can evaporate nearby liquid water droplets, we present a passive anti-frosting surface in which the majority of the surface remains dry indefinitely. We fabricated an aluminum surface exhibiting an array of small metallic fins, where a wicking micro-groove was laser-cut along the top of each fin to produce elevated water ``stripes'' that freeze into ice. As the saturation vapor pressure of ice is less than that of supercooled liquid water, the ice stripes serve as overlapping humidity sinks that siphon all nearby moisture from the air and prevent condensation and frost from forming anywhere else on the surface. Our experimental results show that regions between stripes remain dry even after 24 hours of operation under humid and supercooled conditions. We believe that the presented anti-frosting technology has the potential to help solve the world's multi-billion dollar frosting problem that adversely affects transportation, power generation, and HVAC systems.

Nitrogen frost migration on Triton: A historical model

International Nuclear Information System (INIS)

Spencer, J.R.

1990-01-01

The author presents the results of numerical simulations of the seasonal migration of nitrogen frost on Triton, constrained by Voyager observations of atmospheric pressure, temperature, and albedo distribution. Most of the exposed nitrogen is probably seasonal frost, whose migration can produce major variations in atmospheric pressure. For instance, models explored here predict a tenfold pressure drop in the coming decade. The observed albedo patterns can be understood if fresh nitrogen frost is relatively dark butt brightens with increasing insolation in a manner analogous to the Martian southern CO 2 cap

Heat transfer from a tube immersed in a fluidized bed with frosting

International Nuclear Information System (INIS)

Torikoshi, K.; Kawabata, K.; Yamashita, H.

1990-01-01

Heat-transfer and flow-visualization experiments were performed for a single cooled tube immersed horizontally in a fluidized bed under frosting conditions. Measurements were made from local and average heat-transfer coefficients around the cooled tube surface. Glass beads having nominal diameters of 0.43 mm, 0.89 mm, and 1.6 mm were employed as the bed material. The 30 mm diameter tube was located 100 mm above the distributor. All the results obtained under frosting conditions were for an air temperature of about 5 degrees C and an air relative humidity of about 80 percent. The heat-transfer coefficient with frosting evaluated in this investigation includes the heat-transfer coefficient from the frost surface to the bed and the thermal resistance of the frost layer. Comparisons are made to heat-transfer data without frosting. The heat transfer is found to be larger with frosting than without frosting under the fluidization state

Design of Frost Resistant Pavement Structure Based on Road Weather Stations (RWSs Data

Directory of Open Access Journals (Sweden)

Audrius Vaitkus

2016-12-01

Full Text Available Frost is a decisive factor influencing pavement performance in cold countries. In the EU, millions of euros are spent annually on winter maintenance. About one-third of the maintenance budget is allocated to rehabilitation due to the negative impact of frost. The negative effect of frost is restricted by using non-frost-susceptible materials within the frost zone and regulating water accumulation. However, experience shows that the thickness of constructed pavement structure is often inadequate and that frost penetrates into the subgrade of frost-susceptible materials. The aim of this paper is to introduce the thickness calculation approach of the frost resistant pavement structure using road weather station (RWS data. The subgrade susceptibility to frost and the number of equivalent single axle loads (ESALs are considered as factors too. The calculated thickness of the frost resistant pavement structure is corrected according to the specific local conditions. After performing a statistical analysis of 2012–2014 data pertaining to 26 RWSs, Lithuania was divided into four regions according to the maximum frost depths, where the maximum values depending on RWS location varied from 110.4 cm to 179.1 cm.

Optimization of thermal design for nitrogen shield of JET cryopump

International Nuclear Information System (INIS)

Baxi, C.B.; Obert, W.

1991-11-01

The reference design of JET cryopump nitrogen shield consists of an outer section made of copper chevrons fastened to two cooling tubes and an inner stainless steel section and backing plate with two cooling tubes. These tubes are fed in a parallel flow arrangement. The inlet flow is divided into two parallel paths so that both tubes on either section are always at the same temperature. This arrangement was selected due to concern about conduction between warm and cold parts of the shield during cooldown transients. If the heat loads are unequal, such a parallel flow arrangement can result in flow starvation in the path with higher heat load. This will cause large temperature differences and, ultimately, structural failure. Hence, an analysis was undertaken to investigate the conduction effects in the shield for other flow arrangements. 4 refs., 8 figs

Experimental measurements of the effects of frost formation on heat exchanger performance

International Nuclear Information System (INIS)

Emery, A.F.; Siegel, B.L.

1990-01-01

Frost formation on compact heat exchangers can lead to reductions in heat transfer of the order of 50 to 75% and to substantial increases in pressure drop. These effects are dependent upon the spatial pattern of the frost deposition, the growth history of the frost, and the thicknesses of the frost. This paper describes a series of experiments to measure the effects of frost when cold air (260 - 273 K) is passing through the exchanger. It is found that the thermal performance is a function of time and specific humidity levels while the pressure is function only of the frost thickness and surface roughness

Self-jumping Mechanism of Melting Frost on Superhydrophobic Surfaces

OpenAIRE

Liu, Xiaolin; Chen, Huawei; Zhao, Zehui; Wang, Yamei; Liu, Hong; Zhang, Deyuan

2017-01-01

Frost accretion on surfaces may cause severe problems and the high-efficiency defrosting methods are still urgently needed in many application fields like heat transfer, optical and electric power system, etc. In this study, a nano-needle superhydrophobic surface is prepared and the frosting/defrosting experiments are conducted on it. Three steps are found in the defrosting process: melting frost shrinking and splitting, instantaneous self-triggered deforming followed by deformation-induced m...

Effects of Surface Wettability on the Porosity and Wickability of Frost

Science.gov (United States)

Witt, Katherine; Ahmadi, Farzad; Boreyko, Jonathan

2017-11-01

The wicking of liquids through porous media has been studied for many materials, but never for frost, despite its implications for arctic oil spills and oil-infused surfaces. Here, we characterize silicone oils wicking up frost sheets. A layer of frost was grown on aluminum plates of varying surface wettability: superhydrophilic, hydrophilic, hydrophobic, and superhydrophobic. Once the desired frost thickness was grown, a humidity chamber was used to maintain the frost at the dew point and the bottom of the plate was dipped in a reservoir of fluorescent silicone oil. For all surfaces, the wicking rate of the oil increased with increasing wettability. For the wetting surfaces, this is manifested in the length vs. time data following the classical Washburn equation, exhibiting a power slope of about 1/2 and resulting in a larger effective pore radius with increasing wettability. However, we observed that on the non-wetting surfaces, the discrete distribution of the frosted dew droplets resulted in a new scaling law with a slope much less than 1/2, especially for the superhydrophobic surface which promoted jumping-droplet condensation. This research shows that the wicking of oil up a layer of frost can give insight into the morphology of frost. Conversely, if the underlying wettability of a frost sheet can be controlled, the spread of oil can be widely tuned. This work was supported by a Virginia Space Grant Consortium Undergraduate Research Scholarship (PMPTX7EP).

Argon activation analysis, application to dating by the potassium-argon method; Analyse par activation de l'argon. Application a la datation par la methode potassium-argon

Energy Technology Data Exchange (ETDEWEB)

Dumesnil, P. [Commissariat a l' Energie Atomique, Saclay (France). Centre d' Etudes Nucleaires

1967-07-01

Activation analysis using radiogenic argon-40 has been applied to rock-dating by the K-Ar method. The argon is extracted from the sample, purified, activated to saturation in a flux of 2 X 10{sup 13} neutrons/cm{sup 2} sec{sup -1} and measured by gamma spectroscopy. The sensitivity obtained is such that it is possible to measure amounts of argon corresponding to age of a few thousand years only. However since it has not been possible to measure the amount of pollution of radiogenic argon by atmospheric argon with any accuracy, the measurable age limit is in fact of the order of MY. The method has been applied to basalts from the Mont-Dore region. The results obtained are in fairly good agreement with geological, stratigraphic and paleomagnetic data. (author) [French] L'analyse par activation de l'argon 40 radiogenique a ete appliquee a la datation des roches par la methode K-Ar. L'argon est extrait de l'echantillon, purifie, active a saturation dans un flux de 2.10{sup 13} neutrons.cm{sup -2}.s{sup -1} et mesure en spectrometrie gamma. La sensibilite obtenue est telle qu'il est possible de mesurer des quantites d'argon correspondant a des ages de quelques milliers d'annees seulement. Cependant la correction de pollution de l'argon radiogenique par l'argon atmospherique n'ayant pu etre etablie avec precision, la limite d'age mesurable pratique est de l'ordre de 1 Ma. La methode a ete appliquee aux basaltes de la region du Mont-Dore. Les ages obtenus sont en assez bon accord avec les donnees geologiques, stratigraphiques et paleomagnetiques. (auteur)

On the Effective Thermal Conductivity of Frost Considering Mass Diffusion and Eddy Convection

Science.gov (United States)

Kandula, Max

2010-01-01

A physical model for the effective thermal conductivity of water frost is proposed for application to the full range of frost density. The proposed model builds on the Zehner-Schlunder one-dimensional formulation for porous media appropriate for solid-to-fluid thermal conductivity ratios less than about 1000. By superposing the effects of mass diffusion and eddy convection on stagnant conduction in the fluid, the total effective thermal conductivity of frost is shown to be satisfactorily described. It is shown that the effects of vapor diffusion and eddy convection on the frost conductivity are of the same order. The results also point out that idealization of the frost structure by cylindrical inclusions offers a better representation of the effective conductivity of frost as compared to spherical inclusions. Satisfactory agreement between the theory and the measurements for the effective thermal conductivity of frost is demonstrated for a wide range of frost density and frost temperature.

Broadband Ftmw Spectroscopy of the Urea-Argon and Thiourea-Argon Complexes

Science.gov (United States)

Medcraft, Chris; Bittner, Dror M.; Cooper, Graham A.; Mullaney, John C.; Walker, Nick

2017-06-01

The rotational spectra complexes of argon-urea, argon-thiourea and water-thiourea have been measured by chirped-pulse Fourier transform microwave spectroscopy from 2-18.5 GHz. The sample was produced via laser vaporisation of a rod containing copper and the organic sample as a stream of argon was passed over the surface and subsequently expanded into the vacuum chamber cooling the sample. Argon was found to bind to π system of the carbonyl bond for both the urea and thiourea complexes.

Frost Effects Research Facility

Data.gov (United States)

Federal Laboratory Consortium — Full-scale study in controlled conditionsThe Frost Effects Research Facility (FERF) is the largest refrigerated warehouse in the United States that can be used for a...

Frosted branch angiitis associated with rapidly progressive glomerulonephritis.

Directory of Open Access Journals (Sweden)

Gupta Amod

2002-01-01

Full Text Available Simultaneous occurrence of frosted branch angiitis and immune-mediated rapidly progressive glomerulonephritis is reported. The two diseases possibly share a common immune mechanism. Patients of frosted branch angiitis should undergo complete systemic evaluation including renal function tests even if the patient is systemically asymptomatic.

Numerical and experimental investigation on frosting of energy-recovery ventilator

Science.gov (United States)

Bilodeau, Stephane; Mercadier, Yves; Brousseau, Patrick

Frosting of energy-recovery ventilators results in two major problems: increase of pressure losses and reduction of heat transfer rates. Frost formation of heat and mass exchangers used in these ventilation systems is investigated both experimentally and numerically. A numerical model for the prediction of the thermal behavior of the exchanger is presented. The model is validated with experimental data and is then employed to conduct a parametric study. Results indicate that the absolute humidity is the prevailing parameter for characterizing the frosting phenomenon. A frost-mass-fraction chart is established in terms of the absolute humidity of the warm exhaust stream and of the temperature of the cold supply stream. The effect of time and mass flowrate is also evaluated. The transient three-dimensional model shows that the absolute humidity and the temperature of both air flows vary nonlinearly in the frosted zone.

Trapping cold ground state argon atoms for sympathetic cooling of molecules

OpenAIRE

Edmunds, P. D.; Barker, P. F.

2014-01-01

We trap cold, ground-state, argon atoms in a deep optical dipole trap produced by a build-up cavity. The atoms, which are a general source for the sympathetic cooling of molecules, are loaded in the trap by quenching them from a cloud of laser-cooled metastable argon atoms. Although the ground state atoms cannot be directly probed, we detect them by observing the collisional loss of co-trapped metastable argon atoms using a new type of parametric loss spectroscopy. Using this technique we als...

Frost behavior of a fin surface with temperature variation along heat exchanger fins

International Nuclear Information System (INIS)

Kim, Jung Soo; Kim, Min Soo; Lee, Kwan Soo; Kim, Ook Joong

2007-01-01

This paper presents a mathematical model for predicting the frost behavior formed on heat exchanger fins, considering fin heat conduction under frosting condition. The model is composed of air-side, the frost layer, and fin region, and they are coupled to the frost layer. The frost behavior is more accurately predicted with fin heat conduction considered (Case A) than with a constant fin surface temperature assumed (Case B). The results indicate that the frost thickness and heat transfer rate for Case B are over-predicted in most regions of the fin, as compared to those for Case A. Also, for Case A, the maximum frost thickness varies little with the fin length variations, and the extension of the fin length over 30 mm contributes insignificantly to heat transfer

Argon laser induced changes to the carbonate content of enamel

International Nuclear Information System (INIS)

Ziglo, M.J.; Nelson, A.E.; Heo, G.; Major, P.W.

2009-01-01

Argon laser irradiation can be used to cure orthodontic brackets onto teeth in significantly less time than conventional curing lights. In addition, it has been shown that the argon laser seems to impart a demineralization resistance to the enamel. The purpose of this study was to use surface science techniques to ascertain if this demineralization resistance is possibly a result of a decrease in the carbonate content of enamel. Eleven mandibular third molars previously scheduled for extraction were collected and used in the present study. The teeth were sectioned in two and randomly assigned to either the argon laser (457-502 nm; 250 mW cm -2 ) or the control (no treatment) group. The sections assigned to the argon laser group were cured for 10 s and analyzed. To exaggerate any potential changes the experimental sections were then exposed to a further 110 s of argon laser irradiation. Surface analysis was performed using X-ray photoelectron spectroscopy (XPS) and time-of-flight secondary ion mass spectrometry (ToF-SIMS). The results showed no statistically significant change in the carbonate content of enamel after argon laser irradiation (p > 0.05). Thus, it is suggested that any demineralization resistance imparted to the enamel surface by argon laser irradiation is not due to alterations in carbonate content.

Argon laser induced changes to the carbonate content of enamel

Energy Technology Data Exchange (ETDEWEB)

Ziglo, M.J. [Orthodontic Graduate Program, Faculty of Medicine and Dentistry, University of Alberta, Private Practice, Regina, Saskatchewan (Canada); Nelson, A.E., E-mail: aenelson@dow.com [Department of Chemical and Materials Engineering, Faculty of Engineering, University of Alberta (Canada); Heo, G.; Major, P.W. [Orthodontic Graduate Program, Faculty of Medicine and Dentistry, University of Alberta (Canada)

2009-05-15

Argon laser irradiation can be used to cure orthodontic brackets onto teeth in significantly less time than conventional curing lights. In addition, it has been shown that the argon laser seems to impart a demineralization resistance to the enamel. The purpose of this study was to use surface science techniques to ascertain if this demineralization resistance is possibly a result of a decrease in the carbonate content of enamel. Eleven mandibular third molars previously scheduled for extraction were collected and used in the present study. The teeth were sectioned in two and randomly assigned to either the argon laser (457-502 nm; 250 mW cm{sup -2}) or the control (no treatment) group. The sections assigned to the argon laser group were cured for 10 s and analyzed. To exaggerate any potential changes the experimental sections were then exposed to a further 110 s of argon laser irradiation. Surface analysis was performed using X-ray photoelectron spectroscopy (XPS) and time-of-flight secondary ion mass spectrometry (ToF-SIMS). The results showed no statistically significant change in the carbonate content of enamel after argon laser irradiation (p > 0.05). Thus, it is suggested that any demineralization resistance imparted to the enamel surface by argon laser irradiation is not due to alterations in carbonate content.

Argon laser induced changes to the carbonate content of enamel

Science.gov (United States)

Ziglo, M. J.; Nelson, A. E.; Heo, G.; Major, P. W.

2009-05-01

Argon laser irradiation can be used to cure orthodontic brackets onto teeth in significantly less time than conventional curing lights. In addition, it has been shown that the argon laser seems to impart a demineralization resistance to the enamel. The purpose of this study was to use surface science techniques to ascertain if this demineralization resistance is possibly a result of a decrease in the carbonate content of enamel. Eleven mandibular third molars previously scheduled for extraction were collected and used in the present study. The teeth were sectioned in two and randomly assigned to either the argon laser (457-502 nm; 250 mW cm -2) or the control (no treatment) group. The sections assigned to the argon laser group were cured for 10 s and analyzed. To exaggerate any potential changes the experimental sections were then exposed to a further 110 s of argon laser irradiation. Surface analysis was performed using X-ray photoelectron spectroscopy (XPS) and time-of-flight secondary ion mass spectrometry (ToF-SIMS). The results showed no statistically significant change in the carbonate content of enamel after argon laser irradiation ( p > 0.05). Thus, it is suggested that any demineralization resistance imparted to the enamel surface by argon laser irradiation is not due to alterations in carbonate content.

Frost heaving of planted tree seedlings in the boreal forest of northern Sweden

International Nuclear Information System (INIS)

Goulet, France

2000-01-01

Frost heaving can be a leading cause of tree seedling mortality in many places in the boreal forest of Northern Sweden. The aim of this investigation was to improve our understanding of frost heaving of planted tree seedlings as related to snow cover, scarification, planting methods and soil types. The thesis is based on a review paper, three field experiments and one laboratory experiment. The experiments focus on different methods to control frost heaving of forest tree seedlings and on a number of factors affecting the extent of frost heaving. The review paper identifies the many aspects of frost heaving of forest tree seedlings and agricultural crops based on an intensive review of the research contributions made during the last century. Even if many investigations have been carried out with the aim to decrease the extent of frost heaving, very little quantitative results are available for tree seedlings. In a field experiment, the choice of planting positions was effective in decreasing frost heaving of planted seedlings following mounding or disc-trenching. Seedlings planted in the depressions were largely affected by frost heaving with a maximal vertical displacement of 5.4 cm while frost heaving did not occur on the top of the mound. On the other hand, the planting time and planting depth had no influence on the extent of frost heaving. In another field experiment the size of the scarified patches was strongly correlated to frost heaving which reached between 7.6 and 11.5 cm in 4 and 8-dm patches compared to between 4.4 and 5.3 in non-scarified soil and in a 1-dm patch. Ground vegetation probably decreases the diurnal temperature variation and the number of freezing-thawing cycles. The duration and magnitude of frost temperatures, the frost hour sum, increased with patch size. The difference between the 8-dm and 1-dm patch increased to 2064 hour-degrees at the end of the winter. In larger patches, the planting depth seemed to be effective in reducing the

Frost heaving of planted tree seedlings in the boreal forest of northern Sweden

Energy Technology Data Exchange (ETDEWEB)

Goulet, France

2000-07-01

Frost heaving can be a leading cause of tree seedling mortality in many places in the boreal forest of Northern Sweden. The aim of this investigation was to improve our understanding of frost heaving of planted tree seedlings as related to snow cover, scarification, planting methods and soil types. The thesis is based on a review paper, three field experiments and one laboratory experiment. The experiments focus on different methods to control frost heaving of forest tree seedlings and on a number of factors affecting the extent of frost heaving. The review paper identifies the many aspects of frost heaving of forest tree seedlings and agricultural crops based on an intensive review of the research contributions made during the last century. Even if many investigations have been carried out with the aim to decrease the extent of frost heaving, very little quantitative results are available for tree seedlings. In a field experiment, the choice of planting positions was effective in decreasing frost heaving of planted seedlings following mounding or disc-trenching. Seedlings planted in the depressions were largely affected by frost heaving with a maximal vertical displacement of 5.4 cm while frost heaving did not occur on the top of the mound. On the other hand, the planting time and planting depth had no influence on the extent of frost heaving. In another field experiment the size of the scarified patches was strongly correlated to frost heaving which reached between 7.6 and 11.5 cm in 4 and 8-dm patches compared to between 4.4 and 5.3 in non-scarified soil and in a 1-dm patch. Ground vegetation probably decreases the diurnal temperature variation and the number of freezing-thawing cycles. The duration and magnitude of frost temperatures, the frost hour sum, increased with patch size. The difference between the 8-dm and 1-dm patch increased to 2064 hour-degrees at the end of the winter. In larger patches, the planting depth seemed to be effective in reducing the

Frost risk for overwintering crops in a changing climate

Science.gov (United States)

Vico, Giulia; Weih, Martin

2013-04-01

Climate change scenarios predict a general increase in daily temperatures and a decline in snow cover duration. On the one hand, higher temperature in fall and spring may facilitate the development of overwintering crops and allow the expansion of winter cropping in locations where the growing season is currently too short. On the other hand, higher temperatures prior to winter crop dormancy slow down frost hardening, enhancing crop vulnerability to temperature fluctuation. Such vulnerability may be exacerbated by reduced snow cover, with potential further negative impacts on yields in extremely low temperatures. We propose a parsimonious probabilistic model to quantify the winter frost damage risk for overwintering crops, based on a coupled model of air temperature, snow cover, and crop minimum tolerable temperature. The latter is determined by crop features, previous history of temperature, and snow cover. The temperature-snow cover model is tested against meteorological data collected over 50 years in Sweden and applied to winter wheat varieties differing in their ability to acquire frost resistance. Hence, exploiting experimental results assessing crop frost damage under limited temperature and snow cover realizations, this probabilistic framework allows the quantification of frost risk for different crop varieties, including in full temperature and precipitation unpredictability. Climate change scenarios are explored to quantify the effects of changes in temperature mean and variance and precipitation regime over crops differing in winter frost resistance and response to temperature.

Frost fatigue and spring recovery of xylem vessels in three diffuse-porous trees in situ.

Science.gov (United States)

Christensen-Dalsgaard, Karen K; Tyree, Melvin T

2014-05-01

Frost has been shown to cause frost fatigue (reduced cavitation resistance) in branch segments in the lab. Here, we studied the change in cavitation resistance and percent loss of conductivity (PLC) from fall to spring over 2 consecutive years in three diffuse-porous species in situ. We used the cavitron technique to measure P25 , P50 and P90 (the xylem pressure causing a 25, 50 and 90% conductivity loss) and PLC and stained functioning vessels. Cavitation resistance was reduced by 64-87% (in terms of P50 ), depending on the species and year. P25 was impacted the most and P90 the least, changing the vulnerability curves from s- to r-shaped over the winter in all three species. The branches suffered an almost complete loss of conductivity, but frost fatigue did not necessarily occur concurrently with increases in PLC. In two species, there was a trade-off between conduit size and vulnerability. Spring recovery occurred by growth of new vessels, and in two species by partial refilling of embolized conduits. Although newly grown and functioning conduits appeared more vulnerable to cavitation than year-old vessels, cavitation resistance generally improved in spring, suggesting other mechanisms for partial frost fatigue repair. © 2013 John Wiley & Sons Ltd.

Modeling the airside dynamic behavior of a heat exchanger under frosting conditions

International Nuclear Information System (INIS)

Gao, Tieyu; Gong, Jianying

2011-01-01

A general distributed model with a non-steady-state heat exchanger model coupled with a frost model was developed to study the dynamic behavior of an airside heat exchanger in an air-to-water heat pump heater/chiller unit. The effects of water vapor diffusion and uneven fin temperature distribution were considered. The model was found to agree well with reported experimental results. Compared with the routine model, the present model has higher precision of frost layer thickness especially on the fin surface. Results include the propagation of frost formation along the tube and its effect on the dynamic characteristics of refrigerant, air, and tube sides. According to the results, the temperature difference between air and tube surface temperature was proposed to be the main driving force of frosting. Tube surface temperature is the most important factor affecting frosting when there is little variation in air humidity. Frost at the fin base was found to be thicker than that at the fin tip due to the fact that the frost layer grows faster with lower tube surface temperature

Forecasting Frost Damage: Follow the Water

Science.gov (United States)

Rempel, A. W.

2015-12-01

Frost damage takes place when the pressure exerted against pore walls exceeds the cohesive strength of water-infiltrated rock and causes cracks to extend. Elegant theoretical treatments supported by meticulous field and laboratory observations have combined to unravel the basic mechanical and thermodynamic controls in idealized systems. Frost damage is most vigorous when conditions are cold enough that the net pressure exerted against the pore walls can cause crack extension, yet warm enough to enable the flow that supplies further ice growth in the newly opened space. This insight is applied here to develop practical geomorphic process laws for the effects of frost damage at the larger scales that are relevant for describing the evolution of landscapes. To this end, a direct connection is made between the intensity of frost damage and the porosity increase that results from gradients in water flux under conditions that are cold enough for ice-rock interactions to propagate cracks. This implies that the annual temperature variation at the ground surface can be combined with considerations of heat and mass transport to derive rigorous forecasts of the potential for frost damage that are tied to the increases in water mass that accompany solidification in porous rock. As an example, the image shows the depth-integrated porosity change λ promoted by crack growth at temperatures colder than -ΔTc over an annual cycle for different choices of mean annual temperature MAT and surface amplitude A (assuming a thermal diffusivity of 1 mm2/s and a power-law relationship between permeability and undercooling with exponent α=4, such that a base value of 10-14m2 is reached at a reference undercooling of 0.1 ºC). The abrupt onset in cracking once MAT decreases below a threshold is produced by the requirement that undercooling surpass ΔTc in order to generate sufficient pressures to propagate cracks. The eventual reduction and gradual tail in λ at colder MAT is produced by

Climate change and spring frost damages for sweet cherries in Germany

Science.gov (United States)

Chmielewski, Frank-M.; Götz, Klaus-P.; Weber, Katharina C.; Moryson, Susanne

2018-02-01

Spring frost can be a limiting factor in sweet cherry ( Prunus avium L.) production. Rising temperatures in spring force the development of buds, whereby their vulnerability to freezing temperatures continuously increases. With the beginning of blossom, flowers can resist only light frosts without any significant damage. In this study, we investigated the risk of spring frost damages during cherry blossom for historical and future climate conditions at two different sites in NE (Berlin) and SW Germany (Geisenheim). Two phenological models, developed on the basis of phenological observations at the experimental sweet cherry orchard in Berlin-Dahlem and validated for endodormancy release and for warmer climate conditions (already published), were used to calculate the beginning of cherry blossom in Geisenheim, 1951-2015 (external model validation). Afterwards, on the basis of a statistical regionalisation model WETTREG (RCP 8.5), the frequency of frost during cherry blossom was calculated at both sites for historical (1971-2000) and future climate conditions (2011-2100). From these data, we derived the final flower damage, defined as the percentage of frozen flowers due to single or multiple frost events during blossom. The results showed that rising temperatures in this century can premature the beginning of cherry blossom up to 17 days at both sites, independent of the used phenological model. The frequency and strength of frost was characterised by a high temporal and local variability. For both sites, no significant increase in frost frequency and frost damage during blossom was found. In Geisenheim, frost damages significantly decreased from the middle of the twenty-first century. This study additionally emphasises the importance of reliable phenological models which not only work for current but also for changed climate conditions and at different sites. The date of endodormancy release should always be a known parameter in chilling/forcing models.

The vulnerability of silver fir populations to damage from late frosts

Directory of Open Access Journals (Sweden)

Klisz Marcin

2016-03-01

Full Text Available The aim of the study was to determine the vulnerability of selected silver fir populations to damage from late frost in the climatic conditions of south-eastern Poland. To determine the vulnerability of apical and lateral shoots to damage caused by late frosts, we observed four test plots in 2009 and 2014, each containing progenies of selected seed stands. Our statistical analyses were based on a model incorporating the following variables: site, year, type of frost damage, population as well as the possible interaction between these variables. Significant differences between the populations were found in terms of their sensitivity to damage from low temperature occurring during the growth period. Furthermore, we indirectly demonstrated differences in the severity of late frost on the experimental plots, as well as the intensity and variability of late frost shoot damage. Based on these results, we divided the studied populations into two groups of low (EF, KRA1 and NAR and high (LES2 and BAL2 sensitivity to late frost damage.

Liquid-argon calorimetry

International Nuclear Information System (INIS)

Fabjan, C.W.

1989-01-01

In this paper the viability of liquid-argon calorimetric techniques in the experimental environment of the Superconducting Super Collider (SSC) is briefly analyzed. The authors compare the required and achievable energy resolution with benchmark figures obtained using practical instruments. Comments on the desirable (i.e. required) temporal performance are made and compared with the state of the art. Some of the major engineering challenges are listed, for which solutions will have to be developed if such instruments are to find a place in an SSC experimental area

Molecular polarizabilities and susceptibilities from Frost-model wavefunctions

International Nuclear Information System (INIS)

Amos, A.T.; Yoffe, J.A.

1975-01-01

Average polarizabilities and susceptibilities of a number of molecules are computed from Frost-model wavefunctions using a form of symmetry-adapted double perturbation theory. The anisotropy of α and chi is found for a few molecules using the elliptical Gaussian form of the Frost model. The results obtained are in reasonable agreement with experiment and other calculated values

Utility and Value of Satellite-Based Frost Forecasting for Kenya's Tea Farming Sector

Science.gov (United States)

Morrison, I.

2016-12-01

Frost damage regularly inflicts millions of dollars of crop losses in the tea-growing highlands of western Kenya, a problem that the USAID/NASA Regional Visualization and Monitoring System (SERVIR) program is working to mitigate through a frost monitoring and forecasting product that uses satellite-based temperature and soil moisture data to generate up to three days of advanced warning before frost events. This paper presents the findings of a value of information (VOI) study assessing the value of this product based on Kenyan tea farmers' experiences with frost and frost-damage mitigation. Value was calculated based on historic trends of frost frequency, severity, and extent; likelihood of warning receipt and response; and subsequent frost-related crop-loss aversion. Quantification of these factors was derived through inferential analysis of survey data from 400 tea-farming households across the tea-growing regions of Kericho and Nandi, supplemented with key informant interviews with decision-makers at large estate tea plantations, historical frost incident and crop-loss data from estate tea plantations and agricultural insurance companies, and publicly available demographic and economic data. At this time, the product provides a forecasting window of up to three days, and no other frost-prediction methods are used by the large or small-scale farmers of Kenya's tea sector. This represents a significant opportunity for preemptive loss-reduction via Earth observation data. However, the tea-growing community has only two realistic options for frost-damage mitigation: preemptive harvest of available tea leaves to minimize losses, or skiving (light pruning) to facilitate fast recovery from frost damage. Both options are labor-intensive and require a minimum of three days of warning to be viable. As a result, the frost forecasting system has a very narrow margin of usefulness, making its value highly dependent on rapid access to the warning messages and flexible access

The development of a cryopump for stripper gas pumping in a 30 MV tandem Van de Graaff

International Nuclear Information System (INIS)

Halliday, B.S.

1980-04-01

The development of a cryopump is described for a 30 MV tandem Van de Graaf accelerator to control the vacuum pressure in the beam tube at the centre terminal when a gas stripper is in use. The system has been fully assembled and has been mechanically tested, the cryo pumps have been cooled to 18 0 K and the insulation tested electrically to +- 20 kV between the pump elements and the biased stripper canal. (UK)

Frost on Dunes

Science.gov (United States)

2005-01-01

18 March 2005 This Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC) image shows dark dunes on a crater floor during the southern spring. Some of the dunes have frost on their south-facing slopes. Location near: 52.3oS, 326.7oW Image width: 3 km (1.9 mi) Illumination from: upper left Season: Southern Spring

[Research on quality changes in ginseng stems and leaves before and after frost].

Science.gov (United States)

Zhao, Yan; Ma, Shuang; Cai, En-Bo; Liu, Shuang-Li; Yang, He; Zhang, Lian-Xue; Wang, Shi-Jie

2014-08-01

The present study is to investigate the quality changes of ginseng stems and leaves before and after frost. The contents changes of ginsenoside, free amino acid, and total phenolic compounds, as well as DPPH radical scavenging effect before and after frost were measured. The content of 9 ginsenoside monomer in ginseng stems was decreased except for Rg, and Re after frost, but in ginseng leaves was all decreased. The total content of amino acids was decreased in ginseng stems after frost, while increased in ginseng leaves. The content of phenolic compounds in ginseng stems and leaves were both decreased after frost while the ability of DPPH radical scavenging was improved. The factor of frost has great impact on the quality of ginseng stems and leaves.

Status of the ATLAS Liquid Argon Calorimeter and its Performance

CERN Document Server

Barillari, T; The ATLAS collaboration

2011-01-01

The ATLAS experiment is designed to study the proton-proton collisions produced at the LHC with a centre-of-mass energy of 14 TeV. Liquid argon (LAr) sampling calorimeters are used in ATLAS for all electromagnetic calorimetry covering the pseudorapidity region |eta|<3.2, as well as for hadronic calorimetry from |eta|=1.4 to |eta|=4.8. The calorimeter system consists of an electromagnetic barrel calorimeter and two endcaps with electromagnetic (EMEC), hadronic (HEC) and forward (FCAL) calorimeters. The lead-liquid argon sampling technique with an accordion geometry was chosen for the barrel electromagnetic calorimeter (EMB) and adapted to the endcap (EMEC). This geometry allows a uniform acceptance over the whole azimuthal range without any gap. The hadronic endcap calorimeter (HEC) uses a copper-liquid argon sampling technique with plate geometry and is subdivided into two wheels in depth per end-cap. Finally, the forward calorimeter (FCAL) is composed of three modules featuring cylindrical electrodes ...

Characterization of the radiation field and evaluation of the nuclear responses in the ITER cryopump port cell

Energy Technology Data Exchange (ETDEWEB)

Moro, Fabio, E-mail: fabio.moro@enea.it [ENEA, Fusion Technical Unit, Nuclear Technologies Laboratory, 45th Enrico Fermi St., 00044 Frascati, Rome (Italy); Villari, Rosaria; Flammini, Davide; Podda, Salvatore [ENEA, Fusion Technical Unit, Nuclear Technologies Laboratory, 45th Enrico Fermi St., 00044 Frascati, Rome (Italy); Antipenkov, Alexander; Dremel, Matthias; Levesy, Bruno; Loughlin, Michael [ITER Organization, Route de Vinon sur Verdon, 13115 Saint Paul-lez-Durance (France); Cambi, Gilio; Cepraga, Dan Gabriel [Bologna University, Physics Department, 46th Irnerio St., I-401226 Bologna (Italy); Petrizzi, Luigino [European Commission, DG Research & Innovation G5, CDMA 00/030, B-1049 Brussels (Belgium)

2016-11-01

The ITER main vacuum system consists of six torus exhaust pumps integrated in the Cryostat through dedicated housings at the building B1 level. The Port Cell area outside the cryopump plug is affected by neutrons streaming through the housing structure and diagnostics penetrations. The aim of the study presented in this paper is to perform a complete assessment of the nuclear responses in the Cryopump Port Cell #12 by means of the MCNP-5 Monte Carlo code in a full 3-D geometry. The results of the neutronic analyses provide guidelines for the design and maintenance of the embedded components, ensuring their structural integrity and proper operation. Radiation transport calculations have been carried out to determine the radiation field inside the Port Cell through 3-D neutrons and gamma maps. Nuclear heating induced by neutrons and photons and the absorbed dose during the ITER lifetime on steel and silicon have been estimated in the Port Cell area, in order to assess the nuclear loads that the diagnostics and related electronic components have to withstand. Furthermore, the impact of the gamma-rays emitted by neutron-activated water circulating in the Primary Heat Transfer System have been evaluated on the Port Cell environment: 3-D maps of the gamma flux, nuclear loads on steel/silicon during plasma operation are provided.

Characterization of the radiation field and evaluation of the nuclear responses in the ITER cryopump port cell

International Nuclear Information System (INIS)

Moro, Fabio; Villari, Rosaria; Flammini, Davide; Podda, Salvatore; Antipenkov, Alexander; Dremel, Matthias; Levesy, Bruno; Loughlin, Michael; Cambi, Gilio; Cepraga, Dan Gabriel; Petrizzi, Luigino

2016-01-01

The ITER main vacuum system consists of six torus exhaust pumps integrated in the Cryostat through dedicated housings at the building B1 level. The Port Cell area outside the cryopump plug is affected by neutrons streaming through the housing structure and diagnostics penetrations. The aim of the study presented in this paper is to perform a complete assessment of the nuclear responses in the Cryopump Port Cell #12 by means of the MCNP-5 Monte Carlo code in a full 3-D geometry. The results of the neutronic analyses provide guidelines for the design and maintenance of the embedded components, ensuring their structural integrity and proper operation. Radiation transport calculations have been carried out to determine the radiation field inside the Port Cell through 3-D neutrons and gamma maps. Nuclear heating induced by neutrons and photons and the absorbed dose during the ITER lifetime on steel and silicon have been estimated in the Port Cell area, in order to assess the nuclear loads that the diagnostics and related electronic components have to withstand. Furthermore, the impact of the gamma-rays emitted by neutron-activated water circulating in the Primary Heat Transfer System have been evaluated on the Port Cell environment: 3-D maps of the gamma flux, nuclear loads on steel/silicon during plasma operation are provided.

Observed variations in U.S. frost timing linked to atmospheric circulation patterns.

Science.gov (United States)

Strong, Courtenay; McCabe, Gregory J

2017-05-23

Several studies document lengthening of the frost-free season within the conterminous United States (U.S.) over the past century, and report trends in spring and fall frost timing that could stem from hemispheric warming. In the absence of warming, theory and case studies link anomalous frost timing to atmospheric circulation anomalies. However, recent efforts to relate a century of observed changes in U.S. frost timing to various atmospheric circulations yielded only modest correlations, leaving the relative importance of circulation and warming unclear. Here, we objectively partition the U.S. into four regions and uncover atmospheric circulations that account for 25-48% of spring and fall-frost timing. These circulations appear responsive to historical warming, and they consistently account for more frost timing variability than hemispheric or regional temperature indices. Reliable projections of future variations in growing season length depend on the fidelity of these circulation patterns in global climate models.

Frost as a first wall for the ICF laboratory microfusion facility

International Nuclear Information System (INIS)

Orth, C.D.

1989-01-01

The authors introduce the concept of using frost as the first wall of the ICF Laboratory Microfusion Facility being designed to produce 200-1000 MJ of thermonuclear yield. They present one design incorporating 2cm of frost deposited at 0.1 g/cm/sup 3/ on an LN-cooled fiber-reinforced polymer substrate. They calculate that such a frost layer will protect the substrate from ablation by target x rays and debris, and from shock-induced spallation. Postshot washdown with water should permit low-activation operation, and should preserve the original wall properties. The authors expect the impact of the frost on laser optics to be minimal, and expect the preshot lifetime of thermally unprotected cryogenic targets to be extended by operating the wall at 100-150 K. Moreover, they believe that such a frost first wall involves little technical risk, and will be inexpensive to construct and operate

Frost as a first wall for the ICF Laboratory Microfusion Facility

International Nuclear Information System (INIS)

Orth, C.D.

1988-01-01

We introduce the concept of using frost as the first wall of the ICF Laboratory Microfusion Facility being designed to produce 200--1000 MJ of thermonuclear yield. We present one design incorporating 2 cm of frost deposited at 0.1 g/cm 3 on an LN-cooled fiber-reinforced polymer substrate. We calculate that such a frost layer will protect the substrate from ablation by target x rays and debris, and from shock-induced spallation. Postshot washdown with water should permit low-activation operation, and should preserve the original wall properties. We expect the impact of the frost on laser optics to be minimal, and expect the preshot lifetime of thermally unprotected cryogenic targets to be extended by operating the wall at 100-150 K. Moreover, we believe that such a frost first wall will involve little technical risk, and will be inexpensive to construct and operate. 4 refs., 1 fig

Experimental and numerical study on frost heave of saturated rock under uniform freezing conditions

Science.gov (United States)

Lv, Zhitao; Xia, Caichu; Li, Qiang

2018-04-01

A series of freezing experiments are conducted on saturated sandstone and mortar specimens to investigate the frost heave of saturated rock under uniform freezing conditions. The experimental results show that the frost heave of saturated rock is isotropic under uniform freezing conditions. During the freezing process, three stages are observed in the curves of variation of total frost heaving strain versus time: the thermal contraction stage, the frost heaving stage and the steady stage. Moreover, the amount of final stable frost heave first increases and then decreases with decrease in freezing temperature, and the maximum final stable frost heave occurs at different freezing temperature in saturated sandstone and mortar. Furthermore, a coupled thermal-mechanical (TM) model of frost heave of saturated rock is proposed in which a constraint coefficient \\zeta is used to consider the susceptibility of the internal rock grain structure to the expansion of pore ice. Then, numerical simulations are implemented with COMSOL to solve the governing equations of the TM model. Comparisons of the numerical results with the experimental results are performed to demonstrate the reliability of the model. The influences of elastic modulus and porosity on frost heave are also investigated, and the results show that the total frost heaving strain decreases non-linearly with increasing elastic modulus, and the decrease is significant when the elastic modulus is less than 3000 MPa, or approximately five times the elastic modulus of ice. In addition, the total frost heaving strain increases linearly with increasing porosity. Finally, an empirical equation between total frost heaving strain and freezing temperature is proposed and the equation well describes the variation of total frost heaving strain with freezing temperature.

Species ecology determines the role of nitrogen nutrition in the frost tolerance of pine seedlings.

Science.gov (United States)

Toca, Andrei; Oliet, Juan A; Villar-Salvador, Pedro; Maroto, Judit; Jacobs, Douglass F

2018-01-01

Frost determines the evolution and distribution of plants in temperate and cold regions. Several environmental factors can influence frost acclimation of woody plants but the magnitude and direction of the effect of nitrogen (N) availability is controversial. We studied the effect of N availability on root and shoot frost tolerance in mid-fall and in winter in seedlings of four pines of contrasting ecology: Pinus nigra J.F. Arnold, P. pinaster Ait., P. pinea L. and P. halepensis Mill.. Organ N and soluble sugar concentration, and timing of cessation of shoot elongation were measured to assess the physiological mechanisms underlying frost acclimation. Nitrogen was supplied at high and low rates only during the pre-hardening period and at a moderate N rate during hardening in the fall. Shoot frost tolerance increased over winter while root frost tolerance did not change in any species. Pre-hardening N availability affected the frost tolerance of both roots and shoots, although the effect was species-specific: high N reduced the overall root and shoot frost tolerance in P. pinea and P. halepensis, and increased the frost tolerance in P. nigra, but had no effect in P. pinaster. Nitrogen supply in the fall consistently increased frost tolerance in all species. Differences in frost tolerance among species and N treatments were not explained by variations in organ N or soluble carbohydrate concentration, nor by timing of cessation of shoot elongation; however, the most frost tolerant species ceased elongation earlier than the least frost tolerant species. Despite the close phylogenetic relatedness of the studied species, the effect of N availability on seedling frost tolerance differed among species, indicating that species ecology (especially frost acclimation physiology) and timing of N supply drives the effect of N availability on frost tolerance of pine species. © The Author(s) 2017. Published by Oxford University Press. All rights reserved. For Permissions, please

Analysis Of First Fall And Last Spring Advection and Radiation-Advection Frosts In Azerbaijan Provinces

International Nuclear Information System (INIS)

Noohi, K.; Pedram, M.; Sahraian, F.; Kamali, G. A.

2007-01-01

Atmospheric Science and Meteorological Research Center (ASMERC)Dates of first fall and last spring frosts on the basis of minimum shelter temperature equal or less than 0°C were determined for 12 synoptic stations for period 1986-2000 in Azerbaijan region. The advection frost was determined based on using of synoptic maps and studying of meteorological elements in different hours. In this work, we found that series of first fall and last spring advection and radiation-advection frosts are random and normally distributed. This study shows that on the average advection frosts start from 6 to 40 days later than radiation-advection frosts in fall and ends 2 to 25 days earlier in spring. Potential growing season that is interval between last spring and first fall advection frost is found to be from 5 to 65 days longer than the growing season defined by the interval from last spring to first fall occurrences of minimum temperature equal or less than 0°C. Crop protection against radiation frosts can bring about too much benefit. To assess whether practical protection of some special crops against radiation frosts is done or not, the number of radiation frosts before first advection frost in fall and after last advection frost in spring, were determined

Predictive modeling of freezing and thawing of frost-susceptible soils.

Science.gov (United States)

2015-09-01

Frost depth is an essential factor in design of various transportation infrastructures. In frost : susceptible soils, as soils freezes, water migrates through the soil voids below the freezing line : towards the freezing front and causes excessive he...

Frost formation under different gaseous atmospheres

International Nuclear Information System (INIS)

Fukada, Satoshi; Tsuru, Hisanori; Nishikawa, Masabumi

1995-01-01

Rates of water frost growth in a vessel with a cooled horizontal plate were experimentally determined under reduced pressure atmospheres of hydrogen, helium, methane and nitrogen. The mass deposited on the cooled surface under each of the atmospheres was almost in proportion to time. The Sherwood number under the condition of no mist formation, Sh 0 , in the atmospheres of methane and nitrogen was in good agreement with Catton's equation for natural convection between horizontal parallel plates. Sh 0 in a hydrogen atmosphere was unity, which corresponds to control by molecular diffusion in the stagnant gas. The tendency of the decrease in Sh due to mist formation could be evaluated well by multiplying Sh 0 by a factor ζ CSM . The ζ CSM value was calculated based on the critical supersaturation model as a function of the two interface temperatures and the total pressure. Frost growth rates under each atmosphere were in proportion to [(T S1 -T W1 )t/(1+1/A S1 )] 0.5 . The proportional constant for hydrogen was greater than that for any other tested gas. Agreement and disagreement of the frost effective thermal conductivity with previous models were discussed. (author)

Delayed frost formation on hybrid nanostructured surfaces with patterned high wetting contrast

Science.gov (United States)

Hou, Youmin; Zhou, Peng; Yao, Shuhuai

2014-11-01

Engineering icephobic surfaces that can retard the frost formation and accumulation are important to vehicles, wind turbines, power lines, and HVAC systems. For condensation frosting, superhydrophobic surfaces promote self-removal of condensed droplets before freezing and consequently delay the frost growth. However, a small thermal fluctuation may lead to a Cassie-to-Wenzel transition, and thus dramatically enhance the frost formation and adhesion. In this work, we investigated the heterogeneous ice nucleation on hybrid nanostructured surfaces with patterned high wetting contrast. By judiciously introducing hydrophilic micro-patches into superhydrophobic nanostructured surface, we demonstrated that such a novel hybrid structure can efficiently defer the ice nucleation as compared to a superhydrophobic surface with nanostructures only. We observed efficient droplet jumping and higher coverage of droplets with diameter smaller than 10 μm, both of which suppress frost formation. The hybrid surface avoids the formation of liquid-bridges for Cassie-to-Wenzel transition, therefore eliminating the `bottom-up' droplet freezing from the cold substrate. These findings provide new insights to improve anti-frosting and anti-icing by using heterogeneous wettability in multiscale structures.

Frost Heave in Colloidal Soils

KAUST Repository

Peppin, Stephen; Majumdar, Apala; Style, Robert; Sander, Graham

2011-01-01

We develop a mathematical model of frost heave in colloidal soils. The theory accountsfor heave and consolidation while not requiring a frozen fringe assumption. Two solidificationregimes occur: a compaction regime in which the soil consolidates

Negative corona current pulses in argon and in mixture argon with SF6

International Nuclear Information System (INIS)

Zahoranova, A.; Zahoran, M.; Bucek, A.; Cernak, M.; Bosko, J.

2004-01-01

Waveforms of the first negative current pulses in a short negative point-to plane gap in pure argon and argon with SF 6 admixture have been investigated with a nanosecond time resolution at a gas pressure 50 kPa as a function of applied gap voltage and content of SF 6 in the mixture. We have made an attempt to explain the differences in the discharge development in pure argon and in argon with admixture of SF 6 based on the observed changes of the pulse shape. The experimental results obtained will be discussed in context with existing computer simulation models (Authors)

Effects of environmental factors and management practices on microclimate, winter physiology, and frost resistance in trees.

Science.gov (United States)

Charrier, Guillaume; Ngao, Jérôme; Saudreau, Marc; Améglio, Thierry

2015-01-01

Freezing stress is one of the most important limiting factors determining the ecological distribution and production of tree species. Assessment of frost risk is, therefore, critical for forestry, fruit production, and horticulture. Frost risk is substantial when hazard (i.e., exposure to damaging freezing temperatures) intersects with vulnerability (i.e., frost sensitivity). Based on a large number of studies on frost resistance and frost occurrence, we highlight the complex interactive roles of environmental conditions, carbohydrates, and water status in frost risk development. To supersede the classical empirical relations used to model frost hardiness, we propose an integrated ecophysiologically-based framework of frost risk assessment. This framework details the individual or interactive roles of these factors, and how they are distributed in time and space at the individual-tree level (within-crown and across organs). Based on this general framework, we are able to highlight factors by which different environmental conditions (e.g., temperature, light, flood, and drought), and management practices (pruning, thinning, girdling, sheltering, water aspersion, irrigation, and fertilization) influence frost sensitivity and frost exposure of trees.

Optimum soil frost depth to alleviate climate change effects in cold region agriculture.

Science.gov (United States)

Yanai, Yosuke; Iwata, Yukiyoshi; Hirota, Tomoyoshi

2017-03-21

On-farm soil frost control has been used for the management of volunteer potatoes (Solanum tuberosum L.), a serious weed problem caused by climate change, in northern Japan. Deep soil frost penetration is necessary for the effective eradication of unharvested small potato tubers; however, this process can delay soil thaw and increase soil wetting in spring, thereby delaying agricultural activity initiation and increasing nitrous oxide emissions from soil. Conversely, shallow soil frost development helps over-wintering of unharvested potato tubers and nitrate leaching from surface soil owing to the periodic infiltration of snowmelt water. In this study, we synthesised on-farm snow cover manipulation experiments to determine the optimum soil frost depth that can eradicate unharvested potato tubers without affecting agricultural activity initiation while minimising N pollution from agricultural soil. The optimum soil frost depth was estimated to be 0.28-0.33 m on the basis of the annual maximum soil frost depth. Soil frost control is a promising practice to alleviate climate change effects on agriculture in cold regions, which was initiated by local farmers and further promoted by national and local research institutes.

Optimum soil frost depth to alleviate climate change effects in cold region agriculture

Science.gov (United States)

Yanai, Yosuke; Iwata, Yukiyoshi; Hirota, Tomoyoshi

2017-03-01

On-farm soil frost control has been used for the management of volunteer potatoes (Solanum tuberosum L.), a serious weed problem caused by climate change, in northern Japan. Deep soil frost penetration is necessary for the effective eradication of unharvested small potato tubers; however, this process can delay soil thaw and increase soil wetting in spring, thereby delaying agricultural activity initiation and increasing nitrous oxide emissions from soil. Conversely, shallow soil frost development helps over-wintering of unharvested potato tubers and nitrate leaching from surface soil owing to the periodic infiltration of snowmelt water. In this study, we synthesised on-farm snow cover manipulation experiments to determine the optimum soil frost depth that can eradicate unharvested potato tubers without affecting agricultural activity initiation while minimising N pollution from agricultural soil. The optimum soil frost depth was estimated to be 0.28-0.33 m on the basis of the annual maximum soil frost depth. Soil frost control is a promising practice to alleviate climate change effects on agriculture in cold regions, which was initiated by local farmers and further promoted by national and local research institutes.

Changes in phenology and frost risks of

Directory of Open Access Journals (Sweden)

Thomas Kartschall

2015-04-01

Full Text Available For a retrospective period of 110 years between 1901 and 2010 (observed data, and for the subsequent future period between 2011 and 2100 we calculated the phenological development (bud burst, harvest ripeness, and in particular the spring frost risk (frost after bud burst, as one important derived variable for grapevine (Vitis vinifera L. cv Riesling for the whole of Germany. For the future climate we included two different scenarios (RCP8.5, RCP2.6 each of them containing a triple set with minimum, medium and maximum temperature increase. The time period between 1981 and 2010 as the last three decades in the observed data was chosen as reference. In general we found an acceleration of the phenological development (all main phases mainly beginning in the late 1980s. For the three-decade period between 2031 and 2060 this acceleration will reach 11±3$11\\pm3$ days in the RCP8.5-scenario. The acceleration for the other stages behaved similarly and results in an earlier harvest ripeness of 13±1$13\\pm1$ days. Since a warmer spring in general leads to earlier bud burst, but does not reduce the risk of frost events during this period in the same manner, changes in the risk of spring frost damage were relatively small. For the coming decades this risk will not decrease for all traditional German viticultural regions in the RCP8.5-scenarios; on the contrary, our results suggest it is likely to increase. The results showed an increasing spring frost risk not only for the debated “upcoming” potential viticultural areas in eastern Germany, an effect which will partly also reach the southernmost viticultural areas. This effect in northern and eastern Germany is due to earlier bud burst together with the stronger continental influence, but for the southern and western regions of Germany is mainly due to the even earlier bud burst. This could modify the regionally nuanced character of German wines.

Dedicated Low Latitude Diurnal CO2 Frost Observation Campaigns by the Mars Climate Sounder

Science.gov (United States)

Piqueux, S.; Kass, D. M.; Kleinboehl, A.; Hayne, P. O.; Heavens, N. G.; McCleese, D. J.; Schofield, J. T.; Shirley, J. H.

2017-12-01

In December 2016 (Ls≈280, MY33) and July 2017 (Ls≈30, MY34), the Mars Climate Sounder (MCS) onboard the Mars Reconnaissance Orbiter (MRO) conducted two distinct observation campaigns. The first one aimed at 1) confirming the presence of low latitude diurnal CO2 frost on Mars, and 2) refining the estimated mass of carbon dioxide condensed at the surface, whereas the second campaign was designed to 3) search for temporally and spatially varying spectral characteristics indicative of frost properties (i.e., crystal size, contamination, etc.) and relationship to the regolith. To meet these goals, MCS acquired thermal infrared observations of the surface and atmosphere at variable local times (≈1.70-3.80 h Local True Solar Time) and in the 10°-50°N latitude band where very low thermal inertia material (frost distribution and spectral properties. In addition, pre-frost deposition surface cooling rates are found to be consistent with those predicted by numerical models (i.e., 1-2K per hour). Finally, we observe buffered surface temperatures near the local frost point, indicating a surface emissivity ≈1. (i.e., optically thin frost layers, or dust contaminated frost, or slab-like ice) and no discernable frost metamorphism. We will present a detailed analysis of these new and unique observations, and elaborate on the potential relationship between the regolith and this recurring frost cycle.

Frost resistance of reproductive tissues during various stages of development in high mountain plants.

Science.gov (United States)

Neuner, Gilbert; Erler, Agnes; Ladinig, Ursula; Hacker, Jürgen; Wagner, Johanna

2013-01-01

Frost resistance of reproductive vs aboveground vegetative structures was determined for six common European high alpine plant species that can be exposed to frosts throughout their whole reproductive cycle. Freezing tests were carried out in the bud, anthesis and fruit stage. Stigma and style, ovary, placenta, ovule, flower stalk/peduncle and, in Ranunculus glacialis, the receptacle were separately investigated. In all species, the vegetative organs tolerated on an average 2-5 K lower freezing temperatures than the most frost-susceptible reproductive structures that differed in their frost resistance. In almost all species, stigma, style and the flower stalk/peduncle were the most frost-susceptible reproductive structures. Initial frost damage (LT₁₀) to the most susceptible reproductive structure usually occurred between -2 and -4°C independent of the reproductive stage. The median LT₅₀ across species for stigma and style ranged between -3.4 and -3.7°C and matched the mean ice nucleation temperature (-3.7 ± 1.4°C). In R. glacialis, the flower stalk was the most frost-susceptible structure (-5.4°C), and was in contrast to the other species ice-tolerant. The ovule and the placenta were usually the most frost-resistant structures. During reproductive development, frost resistance (LT₅₀) of single reproductive structures mostly showed no significant change. However, significant increases or decreases were also observed (2.1 ± 1.2 K). Reproductive tissues of nival species generally tolerated lower temperatures than species occurring in the alpine zone. The low frost resistance of reproductive structures before, during and shortly after anthesis increases the probability of frost damage and thus, may restrict successful sexual plant reproduction with increasing altitude. Copyright © Physiologia Plantarum 2012.

Long-term water absorption tests for frost insulation materials taking into account frost attack

Directory of Open Access Journals (Sweden)

Toni A. Pakkala

2014-01-01

Full Text Available Water absorption of several different frost insulation materials was tested for four years. The test took into account both immersion and frost attack to materials. On the basis of the research the water absorption on XPS specimens is significantly minor compared to EPS specimens that were studied. The most significant result was that freezing of test specimens did not affect on water absorption of XPS specimens but had a major effect on water absorption of EPS specimens. With frozen EPS specimen the absorption continued increasing even after 48 months of immersion. Presumably the reason for such a behaviour is that the pore structure of EPS is not able to resist the tension caused by freezing water and therefore cracks are formed. Thus, more water absorbs inside the EPS through the cracks and it causes cracking deeper in the specimen which is why absorption increases after every freezing period.

The drift velocity of excess electrons in fluid methane, argon and mixtures of methane and argon

International Nuclear Information System (INIS)

Engels, J.M.L.

1979-01-01

A description is given of an experimental investigation of the drift velocity of excess electrons in fluid methane at temperatures between 91K and 215K, and at pressures up to 65X10 5 Pa. These measurements that have become possible especially due to the improved purification techniques of the liquids under investigation. The purification prevents the electron from being captured too soon by an electron-impurity. From the results of the measurements in methane it appeared that in some respects the behaviour of excess electrons in methane is qualitatively similar to that in argon. For this reason a number of measurements of the electron drift velocity have been carried out in argon and in mixtures of methane and argon as well. A detailed description of the experimental set-up is presented. The excess electrons are generated with a high-voltage electron gun, which produces a pulse of highly energetic electrons. A fraction of these electrons enters the liquid sample by passing through a thin metal foil which separates the liquid sample and the vacuum present in the electron gun. At the same time the foil is used as one of two plane-parallel electrodes of the measuring capacitor in which the drift velocity of the excess electrons is to be measured. (Auth.)

Potassium-argon technology

International Nuclear Information System (INIS)

Cassignol, Charles; Cornette, Yves; David, Benjamin; Gillot, P.-Y.

1978-04-01

The main features of the method of processing rocks and minerals and measuring the extracted argon, for the purpose of potassium-argon dating are described. It differs in several respects from the conventional one, as described, f.i., in Dalrymple and Lanphere's monography. Principally it was established that the continual purification of the gases in the mass spectrometer cell during the measurement, stops the peaks of current drift, and renders them representative of the introduced argon. This allows on the one hand to improve the reliability and accuracy of measurements, on the other hand to get rid of the isotopic dilution method, with 38 A as a spike. Moreover the reliability of the radiogenic argon is improved by taking into account the mislinearness of the M.S. response. All this results in a higher performance of the K/Ar dating method, especially in the recent ages range. The technological side of the problem was only dealt with [fr

Community impacts of mid-May frost event during an anomalously warm spring

Science.gov (United States)

Hufkens, K.; Sonnentag, O.; Keenan, T. F.; Richardson, A. D.; Melaas, E. K.; Bailey, A.; O'Keefe, J.; Friedl, M. A.

2011-12-01

Global land and ocean surface temperatures of 2010 have gone on record as one of the warmest of the last 131 years. In the northeastern US extraordinarily warm spring temperatures were recorded, averaging +3 °C above the long term mean, causing very early leaf development. However, the entire northeastern US region was hit by a severe frost event. Leveraging the coincidence of an anomalously warm spring and a late spring frost event we assess species specific responses of these combined extremes for three northern hardwood species(sugar maple, American beech, yellow birch) across an elevational gradient. We integrated ground observations with satellite and near-surface remote sensing data to address the following questions: 1) How did different species respond to a gradient in altitude / freezing temperatures? 2) How does phenological strategy influence this response? 3) To what extent were regional effects measurable? 4) How did the late spring frost event alter the carbon balance of a northern hardwood forest? 5) Finally, what changes do we foresee in community ecology? Our results show an early onset for all species, triggered by the anomalously warm spring. However, the three species responded differently to a late spring frost event. Where both yellow birch and American beech remained largely unaffected by frost, by comparison, sugar maple showed severe frost damage with increasing altitude resulting in leaf loss and delayed canopy development. Conservative estimates of gross carbon exchange losses due to the frost event ranged from 63 g C m-2 to 156 g C m-2, or ~5% to ~13 % of the annual gross carbon exchange of a northern hardwood forest. Our results suggest that the additional pressure on forest succession at high altitude range margins due to late spring frost events may provide a competitive advantage for yellow birch and American beech, at the expense of sugar maple. Consequently, a late spring frost does not only affect the short term carbon balance

Risk analysis of first and last frost occurrences in central Alborz region, Iran

NARCIS (Netherlands)

Rahimi, M.; Khalili, A.; Hajjam, S.; Kamali, G.A.; Stigter, C.J.

2007-01-01

Central Alborz is one of the important agricultural regions of Iran. Occurrence of the first frost in fall and the last frost in spring causes damage to the crops in this region every year. Information about the probable dates of frost occurrence helps farmers in preventing or reducing the damages

Impact of abiotic factors on frost resistance and cold acclimation in Salix species and clones

Energy Technology Data Exchange (ETDEWEB)

Fircks, H. von [Swedish Univ. of Agricultural Sciences, Uppsala (Sweden). Dept. of Short Rotation Forestry

1996-12-31

The effects of mineral nitrogen, photoperiod and day-night temperature on frost resistance and growth cessation in Salix species and clones are discussed. Increased nitrogen supply and imbalances between nitrogen and other elements might cause extensive frost damage in plants of Salix. Vegetation frosts below -3 deg C reduces the level of annual yield. Although Salix clones differ in resistance to freezing stress, the capacity to recover and grow after frosts are equal essential properties which affect the growth and biomass production of shoots after night frosts in June. Early autumn frosts causing freezing damage not only may delay the onset of growth cessation and cold acclimation, but also affect the winter survival of shoots. Increased nitrogen supply prior to cold acclimation postponed growth cessation and cold acclimation. Differences in nutrient status in plants cause also differences in retranslocation of mineral nutrients. Absence of damaging autumn frosts allow plants irrespective of nitrogen status to develop a frost resistance of at least - 80 deg C. 21 refs, 1 fig, 3 tabs

Low energy collisions of spin-polarized metastable argon atoms with ground state argon atoms

Science.gov (United States)

Taillandier-Loize, T.; Perales, F.; Baudon, J.; Hamamda, M.; Bocvarski, V.; Ducloy, M.; Correia, F.; Fabre, N.; Dutier, G.

2018-04-01

The collision between a spin-polarized metastable argon atom in Ar* (3p54s, 3P2, M = +2) state slightly decelerated by the Zeeman slower-laser technique and a co-propagating thermal ground state argon atom Ar (3p6, 1S0), both merged from the same supersonic beam, but coming through adjacent slots of a rotating disk, is investigated at the center of mass energies ranging from 1 to 10 meV. The duration of the laser pulse synchronised with the disk allows the tuning of the relative velocity and thus the collision energy. At these sub-thermal energies, the ‘resonant metastability transfer’ signal is too small to be evidenced. The explored energy range requires using indiscernibility amplitudes for identical isotopes to have a correct interpretation of the experimental results. Nevertheless, excitation transfers are expected to increase significantly at much lower energies as suggested by previous theoretical predictions of potentials 2g(3P2) and 2u(3P2). Limits at ultra-low collisional energies of the order of 1 mK (0.086 μeV) or less, where gigantic elastic cross sections are expected, will also be discussed. The experimental method is versatile and could be applied using different isotopes of Argon like 36Ar combined with 40Ar, as well as other rare gases among which Krypton should be of great interest thanks to the available numerous isotopes present in a natural gas mixture.

Opacity measurements in shock-generated argon plasmas

Energy Technology Data Exchange (ETDEWEB)

Erskine, D.

1993-07-01

Dense plasmas having uniform and constant density and temperature are generated by passage of a planar shock wave through gas. The opacity of the plasma is accurately measured versus wavelength by recording the risetime of emitted light. This technique is applicable to a wide variety of species and plasma conditions. Initial experiments in argon have produced plasmas with 2 eV temperatures, 0.004--0.04 g/cm{sup 3} densities, and coupling parameters {Gamma} {approximately}0.3--0.7. Measurements in visible light are compared with calculations using the HOPE code. An interesting peak in the capacity at 400 nm is observed for the first time and is identified with the 4s-5p transition in excited neutral argon atoms.

Experimental study on frosting control of mobile air conditioning system with microchannel evaporator

International Nuclear Information System (INIS)

Qu Xiaohua; Shi Junye; Qi Zhaogang; Chen Jiangping

2011-01-01

In this paper, a newly developed frost control system is proposed. System bench tests and vehicle test in wind tunnel have been carried out to explore the anti-frosting performance of automotive air conditioning system with microchannel evaporator. The experimental results are compared with the baseline conventional laminated evaporator system. The test results show that the installation position of temperature sensor can dramatically affect the anti-frosting performance. The clutch switching on/off temperature range of the microchannel evaporator is also experimentally studied. The test results show that, with a proper installation position and on/off temperature range, the system COP can be improved, and meanwhile the panel vents' air off temperature can be reduced, and temperature swing can be reduced. - Highlights: → The frost control systems were tested with microchannel and laminated evaporators separately. → The installation position of temperature sensor affects the anti-frosting performance. → Temperature control range affects the anti-frosting performance. → The panel vents' air off temperature and swing can be reduced by proper control parameters. → The system COP can be improved by proper control parameters.

Tints, Shades and Frost

Science.gov (United States)

Sterling, Joan

2009-01-01

This article describes a classroom art project inspired by the work of Robert Frost, one of the most acclaimed and beloved American poets of all time. Using tints and shades in a composition, this project demonstrates how quality literature may be incorporated into elementary art lessons in a very useful way, making art an important complement to…

CO2 Frost Phenomenon for Binary System of Methane-Carbon Dioxide Mixtures

Directory of Open Access Journals (Sweden)

Gede Wibawa

2015-12-01

Full Text Available In the present study, the CO2 frost phenomenon of CH4-CO2 mixtures has been observed for the rational design of CO2 removal from natural gas using a controlled freeze out area. The CO2 frost conditions were estimated using the ZNE method and process simulation software (Aspen HYSYS® v7.3. The experiment was carried out using a double pipe heat exchanger (DPHE with the concentration of CO2 in the gas mixture at 5 and 10% and pressure of the gas mixture from 1 to 20 bar. The equilibrium temperature predictions of the ZNE method and the process simulation software only had a slight difference, with a magnitude deviation of less than 1% for pressures below 20 bar and 3% for pressures in the range of 20-30 bar, respectively. In the experimental study, CO2 frost formation was detected at pressures of 1, 5, 10 and 20 bar. The locations of the initial CO2 frost formation were determined using a pressure drop indicator associated with the predicted frost temperatures obtained from the ZNE method and the process simulation software. For all studied variables, the locations of initial CO2 frost formation were found at 0.887-1.531 m from the inlet.

Dissecting the genetic architecture of frost tolerance in Central European winter wheat.

Science.gov (United States)

Zhao, Yusheng; Gowda, Manje; Würschum, Tobias; Longin, C Friedrich H; Korzun, Viktor; Kollers, Sonja; Schachschneider, Ralf; Zeng, Jian; Fernando, Rohan; Dubcovsky, Jorge; Reif, Jochen C

2013-11-01

Abiotic stress tolerance in plants is pivotal to increase yield stability, but its genetic basis is still poorly understood. To gain insight into the genetic architecture of frost tolerance, this work evaluated a large mapping population of 1739 wheat (Triticum aestivum L.) lines and hybrids adapted to Central Europe in field trials in Germany and fingerprinted the lines with a 9000 single-nucleotide polymorphism array. Additive effects prevailed over dominance effects. A two-dimensional genome scan revealed the presence of epistatic effects. Genome-wide association mapping in combination with a robust cross-validation strategy identified one frost tolerance locus with a major effect located on chromosome 5B. This locus was not in linkage disequilibrium with the known frost loci Fr-B1 and Fr-B2. The use of the detected diagnostic markers on chromosome 5B, however, does not allow prediction of frost tolerance with high accuracy. Application of genome-wide selection approaches that take into account also loci with small effect sizes considerably improved prediction of the genetic variation of frost tolerance in wheat. The developed prediction model is valuable for improving frost tolerance because this trait displays a wide variation in occurrence across years and is therefore a difficult target for conventional phenotypic selection.

Vulnerability assessment to frost disaster in dieng volcanic highland using spatial multi-criteria evaluation

Science.gov (United States)

Pradana, A.; Rahmanu, Y. A.; Prabaningrum, I.; Nurafifa, I.; Hizbaron, D. R.

2018-04-01

Dieng Volcanic Highland is one of frost disaster prone area which is very unique phenomenon in tropical region. Frost indicated by appearance of frozen dew or ice layer on the ground or vegetation surface due air inversion and cold temperatures during midnight in dry season. Appearance of frost significantly causes plant damage and losses on agricultural land, while the impacts were strongly influenced by level of vulnerability within agricultural communities. This study aims to analyze the impact of frost on agricultural land in Dieng, to identify characteristics of physical, social, economic vulnerability and coping capacity of agricultural communities to frost disaster in Dieng, and to estimate total vulnerability of frost disasters in Dieng through SMCE scenario. Research was conducted in Dieng Village, Wonosobo and Dieng Kulon Village, Banjarnegara. Method to assess vulnerability level is performed by Spatial Multi Criteria Evaluation (SMCE) method using ILWIS software through a combination of physical, social, and economic vulnerability regarding frost hazard, as well as coping capacity of farmers. Data collected by interview within different agricultural plots using questionnaire and in-depth interview method on frost affected agricultural land. Impact of frost mostly causes damage on potato agricultural land than any other types of commodities, such as carrot, leek or cabbage. Losses varies in range of 0 million to 55 million rupiah, at most events in range of 10 million to 15 million rupiah during frost season on July-August-September. Main factors determining vulnerability comes from crop losses, preparedness effort, and type of commodity. Agricultural land dominated by high level physical vulnerability (95.37 percent), high level social vulnerability (70.79 percent), moderate level economic vulnerability (79.23 percent) and moderate level coping capacity (73.18 percent). All five scenarios indicated that level of total vulnerability vary only from

Frost hardiness of tree species is independent of phenology and ...

Indian Academy of Sciences (India)

The differences in timing in bud burst between species have been interpreted as an adaptation to late frost events in spring. Thus, it has been suggested that the degree of frost susceptibility of leaves is species-specific and depends on the species' phenology and geographic distribution range. To test for relationships ...

[Occurrence and control of frost in Tilia amurensis and Fraxinus mandshurica young plantations].

Science.gov (United States)

Chen, X; Zhang, Y; Ma, H

2000-12-01

The changes of minimum temperature periodical biological phenomena and frost in yound Tilia amurensis and Fraxinus mandshurica plantation stands were systematically analyzed based on the vertical gradient observation and plot investigation. Meanwhile, the resistance of Tilia amurensis to late frost was also studied. The results showed that the phenophase of T. amurensis was later than that of F. mandshurica. Influenced by significant temperature inversions in this area, the phenophase of T. amurensis and F. mandshurica changed regularly in different aspects and slope positions. The sprouts on west slope started earlier than that on east slope. The higher they grew on the slope, the earlier they sprouted, with the earliest sprout at the top of slope. Late frost in this area only took place when the trees were sprouting, but air temperature decreased significantly at the same time. The degree of injury from the late frost could be controlled effectively by selecting suitable site. Sites down the slope, especially the east slope, were not suitable for T. amurensis and F. mandshurica plantation in this research area. Chemical treatment and biological shading could prevent late frost injury through putting off sprout. Mixed plantations could prevent F. mandshurica and T. anurensis from late frost injury significantly, and the frost injury index and the proportion of the tree number of different injury grades were lower than those in pure stands.

Argon in action

CERN Multimedia

Corinne Pralavorio

2015-01-01

Over the past few days, the SPS has been accelerating argon ions, which have started to be sent to the NA61/SHINE experiment. This operating mode, using a new type of ion, required a number of modifications to the accelerator.   Picture 1: a “super-cycle” of the SPS, featuring a proton cycle for the LHC, followed by an argon ion cycle for the North Area. Today, the accelerators are once again juggling particles and even performing completely new tricks. The SPS is supplying beams of argon ions for the first time, at energies never before achieved for this type of beam. They are destined for the NA61/SHINE experiment (see box) located in the North Area, which began receiving the beams on 11 February. Argon ions have a relatively large mass, as they consist of 40 nucleons, so they can be used in a similar way to lead ions. The main difficulty in accelerating them lies in the SPS, where the variation in acceleration frequency is limited. “The SPS was designed for a...

A method for assessing frost damage risk in sweet cherry orchards of South Patagonia

NARCIS (Netherlands)

Cittadini, E.D.; Ridder, de N.; Peri, P.L.; Keulen, van H.

2006-01-01

Quantification of frost damage risk is important in planning the development of new orchard areas and for decision-making on design and installation of frost control systems. The objective of this study was to develop a comprehensive method to quantify frost damage risk in different sweet cherry

Crushed aggregates for roads and their properties for frost protection

Science.gov (United States)

Kuznetsova, Elena; Willy Danielsen, Svein

2015-04-01

Crushed aggregates for roads and their properties for frost protection Elena Kuznetsova, NTNU and Svein Willy Danielsen, SINTEF With natural (fluvial, glaciofluvial) sand/gravel resources being rapidly depleted in many countries, the last decade has seen a significant trend towards using more alternative materials for construction purpose. In Norway the development and implementation of crushed aggregate technology has been the most important way to get around the problem with increased resource scarcity. Today Norway is one the European countries with the highest percentage of crushed/manufactured aggregates. A crushed product will reveal a different particle size distribution, a sharper, more angular particle shape, and not least - a significantly different mineral composition. The latter may often be characterised by more polymineral composition, and it will also much more depend on the local bedrock. When handled with care and knowledge, these differences can give the user a lot of new opportunities relating to materials design. Norwegian road construction practice has changed significantly during the last 40 years due to the replacement of gravel by crushed rock materials in the granular layers of the pavements. The use of non-processed rock materials from blasting was allowed in the subbase layer until 2012. This was a reason for a lot of problems with frost heaving due to inhomogeneity of this material, and in practice it was difficult to control the size of large stones. Since 2012 there is a requirement that rock materials for use in the subbase layer shall be crushed (Handbook N200, 2014). During the spring 2014 The Norwegian Public Roads Administration introduced a new handbook with requirements for roads construction in Norway, including new specifications for the frost protection layer. When pavements are constructed over moist and/or frost susceptible soils in cold and humid environments, the frost protection layer also becomes a very important part

Genetic architecture of winter hardiness and frost tolerance in triticale.

Directory of Open Access Journals (Sweden)

Wenxin Liu

Full Text Available Abiotic stress experienced by autumn-sown crops during winter is of great economic importance as it can have a severe negative impact on yield. In this study, we investigated the genetic architecture of winter hardiness and frost tolerance in triticale. To this end, we used a large mapping population of 647 DH lines phenotyped for both traits in combination with genome-wide marker data. Employing multiple-line cross QTL mapping, we identified nine main effect QTL for winter hardiness and frost tolerance of which six were overlapping between both traits. Three major QTL were identified on chromosomes 5A, 1B and 5R. In addition, an epistasis scan revealed the contribution of epistasis to the genetic architecture of winter hardiness and frost tolerance in triticale. Taken together, our results show that winter hardiness and frost tolerance are complex traits that can be improved by phenotypic selection, but also that genomic approaches hold potential for a knowledge-based improvement of these important traits in elite triticale germplasm.

The effects of design and operating factors on the frost growth and thermal performance of a flat plate fin-tube heat exchanger under the frosting condition

International Nuclear Information System (INIS)

Lee, Kwan Soo; Kim, Woo Seung

1999-01-01

An experimental study of the effects of various factors(fin pitch, fin arrangement, air temperature, air humidity, and air velocity) on the frost growth and thermal performance of a fin-tube heat exchanger has been conducted under the frosting condition. It is found that the thermal performance of a heat exchanger is closely related to the blockage ratio of the air flow passages due to the frost growth. The maximum allowable blockage ratio is used to determine the criteria for the optimal operating conditions of a fin-tube heat exchanger. It is also shown that heat transfer rate of heat exchanger with staggered fin arrangement increases about 17% and the time required for heat transfer rate to reach a maximum value becomes longer, compared with those of an inline fin-tube heat exchanger under the frosting condition. The energy transfer resistance between the air and coolant decreases with the increase of inlet air temperature and velocity and with decreasing inlet air humidity

A new model for predicting performance of fin-and-tube heat exchanger under frost condition

International Nuclear Information System (INIS)

Cui, J.; Li, W.Z.; Liu, Y.; Zhao, Y.S.

2011-01-01

Accurate prediction of frost characteristics has crucial influence on designing effective heat exchangers. In this paper, a new CFD (Computational Fluid Dynamics) model has been proposed to predict the frost behaviour. The initial period of frost formation can be predicted and the influence of surface structure can be considered. The numerical simulations have been carried out to investigate the performance of fin-and-tube heat exchanger under frost condition. The results have been validated by comparison of simulations with the data computed by empirical formulas. The transient local frost formation has been obtained. The average frost thickness, heat exchanger coefficient and pressure drop on air side has been analysed as well. In addition, the influence factors have also been discussed, such as fin pitch, relative humidity, air flow rate and evaporating temperature of refrigerant.

Vacuum exhaustion system for thermonuclear reactor and cryopump thereof

International Nuclear Information System (INIS)

Kobayashi, Shigetada.

1992-01-01

An impurity removing device is connected to a gas exhaust side of a plasma vacuum vessel by way of a gate valve, a cryopump is connected to the exit side of the device by way of an exit valve, a fuel transfer line is disposed for transferring fuels to a fuel purification system and a vacuum pump line is disposed to an exhaust gas line. Further, a tritium monitor is disposed to an exhaustion line and the line on the side of the exit of the monitor is branched into two ways, in which a tritium transfer pipe is disposed to one of them and an atmosphere release pipe is disposed on the other of them by way of an atmosphere releasing valve. Further, a condensation shebron is disposed for flowing in and out fuel isotope gases discharged from the plasma vacuum vessel, and a funnel discharge pipe is disposed for discharging a liquefied and condensed fluid. Since the gases to be exhausted are liquefied and condensed without coagulation or coagulation products are removed while operating the pump, the exhaust gases are processed continuously to reduce tritium inventory and make the regeneration step unnecessary and remarkably improve the heat efficiency. (N.H.)

Frost susceptibility of sub-base gravel used in Pearl-Chain Bridges: an experimental investigation

DEFF Research Database (Denmark)

Lund, Mia Schou Møller; Hansen, Kurt Kielsgaard; Andersen, Iben Brøndum

2016-01-01

This study investigates frost susceptibility of sub-base gravel determined by the ASTM D5918-13 standard as a conservative estimate of the frost heave risk of fill in overfilled arch bridges, particularly in Pearl-Chain Bridges. Frost heave of granular materials has been of great research interes...

Vacuum leak test technique of JT-60

International Nuclear Information System (INIS)

Kaminaga, Atsushi; Arai, Takashi; Kodama, Kozo; Sasaki, Noboru; Saidoh, Masahiro

1998-01-01

Since a vacuum vessel of JT-60 is very large (167 m 3 ) and is combined with many components, such as magnetic coils, neutral beam injection systems and RF heating systems, etc., the position of leak testing exceeds 700. The two kind of techniques for vacuum leak test used in JT-60 has been described. Firstly the probe helium gas can be fed remotely in the three-dimensionally sectioned 54 regions of the JT-60 torus. The leak test was very rapidly performed by using this method. Secondly the helium detector system has been modified by the additional installation of the cryopump, which reduced the background level of the deuterium gas. The sensitivity of vacuum leak test with the cryopump was two orders of magnitude larger than that of without it. The examples of the performed vacuum leak test are stated. The vacuum leaks during experiments were 9 times. They were caused by thermal strain and plasma discharge. The vacuum leaks just after maintenance are 36 times which mainly caused by mis-installation. (author)

Frost-free Dunes

Science.gov (United States)

2006-01-01

[figure removed for brevity, see original site] Context image for PIA03291 Frost-free Dunes These dark dunes are frost covered for most of the year. As southern summer draws to a close, the dunes have been completely defrosted. Image information: VIS instrument. Latitude -66.6N, Longitude 37.0E. 34 meter/pixel resolution. Note: this THEMIS visual image has not been radiometrically nor geometrically calibrated for this preliminary release. An empirical correction has been performed to remove instrumental effects. A linear shift has been applied in the cross-track and down-track direction to approximate spacecraft and planetary motion. Fully calibrated and geometrically projected images will be released through the Planetary Data System in accordance with Project policies at a later time. NASA's Jet Propulsion Laboratory manages the 2001 Mars Odyssey mission for NASA's Office of Space Science, Washington, D.C. The Thermal Emission Imaging System (THEMIS) was developed by Arizona State University, Tempe, in collaboration with Raytheon Santa Barbara Remote Sensing. The THEMIS investigation is led by Dr. Philip Christensen at Arizona State University. Lockheed Martin Astronautics, Denver, is the prime contractor for the Odyssey project, and developed and built the orbiter. Mission operations are conducted jointly from Lockheed Martin and from JPL, a division of the California Institute of Technology in Pasadena.

A comparison of Frost expression among species and life stages of Drosophila.

Science.gov (United States)

Bing, X; Zhang, J; Sinclair, Brent J

2012-02-01

Frost (Fst) is a gene associated with cold exposure in Drosophila melanogaster. We used real-time PCR to assess whether cold exposure induces expression of Fst in 10 different life stages of D. melanogaster, and adults of seven other Drosophila species. We exposed groups of individuals to 0 °C (2 h), followed by 1 h recovery (22 °C). Frost was significantly upregulated in response to cold in eggs, third instar larvae, and 2- and 5-day-old male and female adults in D. melanogaster. Life stages in which cold did not upregulate Fst had high constitutive expression. Frost is located on the opposite strand of an intron of Diuretic hormone (DH), but cold exposure did not upregulate DH. Frost orthologues were identified in six other species within the Melanogaster group (Drosophila sechellia, Drosophila simulans, Drosophila yakuba, Drosophila erecta, Drosophila ananassae and Drosophila mauritiana). Frost orthologues were upregulated in response to cold exposure in both sexes in adults of all of these species. The predicted structure of a putative Frost consensus protein shows highly conserved tandem repeats of motifs involved in cell signalling (PEST and TRAF2), suggesting that Fst might encode an adaptor protein involved in acute stress or apoptosis signalling in vivo. © 2011 The Authors. Insect Molecular Biology © 2011 The Royal Entomological Society.

Thermophysical properties of multi-shock compressed dense argon.

Science.gov (United States)

Chen, Q F; Zheng, J; Gu, Y J; Chen, Y L; Cai, L C; Shen, Z J

2014-02-21

In contrast to the single shock compression state that can be obtained directly via experimental measurements, the multi-shock compression states, however, have to be calculated with the aid of theoretical models. In order to determine experimentally the multiple shock states, a diagnostic approach with the Doppler pins system (DPS) and the pyrometer was used to probe multiple shocks in dense argon plasmas. Plasma was generated by a shock reverberation technique. The shock was produced using the flyer plate impact accelerated up to ∼6.1 km/s by a two-stage light gas gun and introduced into the plenum argon gas sample, which was pre-compressed from the environmental pressure to about 20 MPa. The time-resolved optical radiation histories were determined using a multi-wavelength channel optical transience radiance pyrometer. Simultaneously, the particle velocity profiles of the LiF window was measured with multi-DPS. The states of multi-shock compression argon plasma were determined from the measured shock velocities combining the particle velocity profiles. We performed the experiments on dense argon plasmas to determine the principal Hugonoit up to 21 GPa, the re-shock pressure up to 73 GPa, and the maximum measure pressure of the fourth shock up to 158 GPa. The results are used to validate the existing self-consistent variational theory model in the partial ionization region and create new theoretical models.

Increasing frost risk associated with advanced citrus flowering dates in Kerman and Shiraz, Iran: 1960-2010.

Science.gov (United States)

Fitchett, Jennifer M; Grab, Stefan W; Thompson, Dave I; Roshan, Gholamreza

2014-10-01

Flowering dates and the timing of late season frost are both driven by local ambient temperatures. However, under climatic warming observed over the past century, it remains uncertain how such impacts affect frost risk associated with plant phenophase shifts. Any increase in frost frequency or severity has the potential to damage flowers and their resultant yields and, in more extreme cases, the survival of the plant. An accurate assessment of the relationship between the timing of last frost events and phenological shifts associated with warmer climate is thus imperative. We investigate spring advances in citrus flowering dates (orange, tangerine, sweet lemon, sour lemon and sour orange) for Kerman and Shiraz, Iran from 1960 to 2010. These cities have experienced increases in both T max and T min, advances in peak flowering dates and changes in last frost dates over the study period. Based on daily instrumental climate records, the last frost dates for each year are compared with the peak flowering dates. For both cities, the rate of last frost advance lags behind the phenological advance, thus increasing frost risk. Increased frost risk will likely have considerable direct impacts on crop yields and on the associated capacity to adapt, given future climatic uncertainty.

Summary of theory and techniques, sample selection and project organization for potassium-argon, rubidium-strontium and fission track dating and strontium isotope studies

International Nuclear Information System (INIS)

Adams, C.J.; Graham, I.J.; Seward, D.

1987-02-01

A brief outline is given of the theory and techniques of the potassium-argon, rubidium-strontium and fission-track dating methods and related isotope studies which are currently in use at the Institute of Nuclear Sciences, DSIR. Some limitations of each technique are set out in terms of age range and materials for dating, and the appropriate choice of various mineral and rock types and subsequent age interpretations are discussed. The organisation of project proposals and categories is described and procedures for sample submission and documentation are given

Water frost on Charon

Science.gov (United States)

Buie, Marc W.; Cruikshank, Dale P.; Lebofsky, Larry A.; Tedesco, Edward F.

1987-01-01

New spectra of the Pluto-Charon system taken just before and during a total eclipse of the satellite are presented. The spectrum of Charon extracted from the data reveals the signature of water ice. There is no evidence for any methane or ammonia frost on the surface of Charon. The significance of these findings for the evolution of the Pluto-Charon system are discussed.

Frost Forecasting for Fruitgrowers

Science.gov (United States)

Martsolf, J. D.; Chen, E.

1983-01-01

Progress in forecasting from satellite data reviewed. University study found data from satellites displayed in color and used to predict frost are valuable aid to agriculture. Study evaluated scheme to use Earth-temperature data from Geostationary Operational Environmental Satellite in computer model that determines when and where freezing temperatures endanger developing fruit crops, such as apples, peaches and cherries in spring and citrus crops in winter.

Tests on fast heating for the regeneration process of ITER cryopumps

International Nuclear Information System (INIS)

Day, C.; Kammerer, B.; Mack, A.

1996-10-01

Within the framework of the European Fusion Technology Programme, a primary vacuum pump for the ITER reactor is being developed. As the tritium accumulated by the pumps must be limited, short pumping cycles are necessary and as a consequence to that regeneration times of about 4 min only are required by the intermittently working cryopumps; approximately 60 s are available for the heating process from LHe temperature (4.2 K) to LN 2 temperature (77 K). Methods for fast heating were tested in component tests. The heating tests were performed at the TITAN test facility. According to the basic planning, the LHe-cooled panel consisted of seven flow channels in quilted design (500 x 350 mm 2 ); the detailed planning meanwhile showed that a smaller number of channels per panel will be sufficient. The panel was mounted in a LN 2 -cooled rig, which worked as first pumping stage. After having worked out a screening study comprehensive test series with three different heating methods were performed. (orig.) [de

Managing potato biodiversity to cope with frost risk in the high Andes: a modeling perspective.

Science.gov (United States)

Condori, Bruno; Hijmans, Robert J; Ledent, Jean Francois; Quiroz, Roberto

2014-01-01

Austral summer frosts in the Andean highlands are ubiquitous throughout the crop cycle, causing yield losses. In spite of the existing warming trend, climate change models forecast high variability, including freezing temperatures. As the potato center of origin, the region has a rich biodiversity which includes a set of frost resistant genotypes. Four contrasting potato genotypes--representing genetic variability--were considered in the present study: two species of frost resistant native potatoes (the bitter Solanum juzepczukii, var. Luki, and the non-bitter Solanum ajanhuiri, var. Ajanhuiri) and two commercial frost susceptible genotypes (Solanum tuberosum ssp. tuberosum var. Alpha and Solanum tuberosum ssp. andigenum var. Gendarme). The objective of the study was to conduct a comparative growth analysis of four genotypes and modeling their agronomic response under frost events. It included assessing their performance under Andean contrasting agroecological conditions. Independent subsets of data from four field experiments were used to parameterize, calibrate and validate a potato growth model. The validated model was used to ascertain the importance of biodiversity, represented by the four genotypes tested, as constituents of germplasm mixtures in single plots used by local farmers, a coping strategy in the face of climate variability. Also scenarios with a frost routine incorporated in the model were constructed. Luki and Ajanhuiri were the most frost resistant varieties whereas Alpha was the most susceptible. Luki and Ajanhuiri, as monoculture, outperformed the yield obtained with the mixtures under severe frosts. These results highlight the role played by local frost tolerant varieties, and featured the management importance--e.g. clean seed, strategic watering--to attain the yields reported in our experiments. The mixtures of local and introduced potatoes can thus not only provide the products demanded by the markets but also reduce the impact of frosts

Managing potato biodiversity to cope with frost risk in the high Andes: a modeling perspective.

Directory of Open Access Journals (Sweden)

Bruno Condori

Full Text Available Austral summer frosts in the Andean highlands are ubiquitous throughout the crop cycle, causing yield losses. In spite of the existing warming trend, climate change models forecast high variability, including freezing temperatures. As the potato center of origin, the region has a rich biodiversity which includes a set of frost resistant genotypes. Four contrasting potato genotypes--representing genetic variability--were considered in the present study: two species of frost resistant native potatoes (the bitter Solanum juzepczukii, var. Luki, and the non-bitter Solanum ajanhuiri, var. Ajanhuiri and two commercial frost susceptible genotypes (Solanum tuberosum ssp. tuberosum var. Alpha and Solanum tuberosum ssp. andigenum var. Gendarme. The objective of the study was to conduct a comparative growth analysis of four genotypes and modeling their agronomic response under frost events. It included assessing their performance under Andean contrasting agroecological conditions. Independent subsets of data from four field experiments were used to parameterize, calibrate and validate a potato growth model. The validated model was used to ascertain the importance of biodiversity, represented by the four genotypes tested, as constituents of germplasm mixtures in single plots used by local farmers, a coping strategy in the face of climate variability. Also scenarios with a frost routine incorporated in the model were constructed. Luki and Ajanhuiri were the most frost resistant varieties whereas Alpha was the most susceptible. Luki and Ajanhuiri, as monoculture, outperformed the yield obtained with the mixtures under severe frosts. These results highlight the role played by local frost tolerant varieties, and featured the management importance--e.g. clean seed, strategic watering--to attain the yields reported in our experiments. The mixtures of local and introduced potatoes can thus not only provide the products demanded by the markets but also reduce the

The Argon Geochronology Experiment (AGE)

Science.gov (United States)

Swindle, T. D.; Bode, R.; Fennema, A.; Chutjian, A.; MacAskill, J. A.; Darrach, M. R.; Clegg, S. M.; Wiens, R. C.; Cremers, D.

2006-01-01

This viewgraph presentation reviews the Argon Geochronology Experiment (AGE). Potassium-Argon dating is shown along with cosmic ray dating exposure. The contents include a flow diagram of the Argon Geochronology Experiment, and schematic diagrams of the mass spectrometer vacuum system, sample manipulation mechanism, mineral heater oven, and the quadrupole ion trap mass spectrometer. The Laser-Induced Breakdown Spectroscopy (LIBS) Operation with elemental abundances is also described.

Reconstructing patterns of temperature, phenology, and frost damage over 124 years: spring damage risk is increasing.

Science.gov (United States)

Augspurger, Carol K

2013-01-01

Climate change, with both warmer spring temperatures and greater temperature fluctuations, has altered phenologies, possibly leading to greater risk of spring frost damage to temperate deciduous woody plants. Phenological observations of 20 woody species from 1993 to 2012 in Trelease Woods, Champaign County, Illinois, USA, were used to identify years with frost damage to vegetative and reproductive phases. Local temperature records were used in combination with the phenological observations to determine what combinations of the two were associated with damage. Finally, a long-term temperature record (1889-1992) was evaluated to determine if the frequency of frost damage has risen in recent decades. Frost Frost damage occurred in five years in the interior and in three additional years at only the forest edge. The degree of damage varied with species, life stage, tissue (vegetative or reproductive), and phenological phase. Common features associated with the occurrence of damage to interior plants were (1) a period of unusual warm temperatures in March, followed by (2) a frost event in April with a minimum temperature frost damage increased significantly, from 0.03 during 1889-1979 to 0.21 during 1980-2012. When the criteria were "softened" to frost damage events more common.

Void structure of concrete with superabsorbent polymers and its relation to frost resistance of concrete

DEFF Research Database (Denmark)

Hasholt, Marianne Tange; Jensen, Ole Mejlhede; Laustsen, Sara

2013-01-01

the difference between poor and satisfactory frost-resistance. Furthermore, the results indicate that voids created directly by SAP protect concrete against frost deterioration just like other air voids; if the concrete contains enough SAP voids, these alone can provide sufficient frost resistance. © 2013 RILEM....

Simulation of argon response and light detection in the DarkSide-50 dual phase TPC

Energy Technology Data Exchange (ETDEWEB)

Agnes, P.; et al.

2017-07-18

A Geant4-based Monte Carlo package named G4DS has been developed to simulate the response of DarkSide-50, an experiment operating since 2013 at LNGS, designed to detect WIMP interactions in liquid argon. In the process of WIMP searches, DarkSide-50 has achieved two fundamental milestones: the rejection of electron recoil background with a power of ~10^7, using the pulse shape discrimination technique, and the measurement of the residual 39Ar contamination in underground argon, ~3 orders of magnitude lower with respect to atmospheric argon. These results rely on the accurate simulation of the detector response to the liquid argon scintillation, its ionization, and electron-ion recombination processes. This work provides a complete overview of the DarkSide Monte Carlo and of its performance, with a particular focus on PARIS, the custom-made liquid argon response model.

Applying Fibre-Optic Distributed Temperature Sensing to Near-surface Temperature Dynamics of Broadacre Cereals During Radiant Frost Events.

Science.gov (United States)

Stutsel, B.; Callow, J. N.

2017-12-01

Radiant frost events, particularly those during the reproductive stage of winter cereal growth, cost growers millions of dollars in lost yield. Whilst synoptic drivers of frost and factors influencing temperature variation at the landscape scale are relatively well understood, there is a lack of knowledge surrounding small-scale temperature dynamics within paddocks and plot trials. Other work has also suggested a potential significant temperature gradient (several degrees) vertically from ground to canopy, but this is poorly constrained experimentally. Subtle changes in temperature are important as frost damage generally occurs in a very narrow temperature range (-2 to -5°C). Once a variety's damage threshold is reached, a 1°C difference in minimum temperature can increase damage from 10 to 90%. This study applies Distributed Temperature Sensing (DTS) using fibre optics to understand how minimum temperature evolves during a radiant frost. DTS assesses the difference in attenuation of Raman scattering of a light pulse travelling along a fibre optic cable to measure temperature. A bend insensitive multimode fibre was deployed in a double ended duplex configuration as a "fence" run through four times of sowing at a trial site in the Western Australian Wheatbelt. The fibre optic fence was 160m long and 800mm tall with the fibre optic cable spaced 100mm apart vertically, and calibrated in ambient water ( 10 to 15oC) and a chilled glycol ( -8 to-10 oC) baths. The temperature measurements had a spatial resolution of 0.65m and temporal resolution of 60s, providing 2,215 measurements every minute. The results of this study inform our understanding of the subtle temperature changes from the soil to canopy, providing new insight into how to place traditional temperature loggers to monitor frost damage. It also addresses questions of within-trial temperature variability, and provides an example of how novel techniques such as DTS can be used to improve the way temperature

On Localized Vapor Pressure Gradients Governing Condensation and Frost Phenomena.

Science.gov (United States)

Nath, Saurabh; Boreyko, Jonathan B

2016-08-23

Interdroplet vapor pressure gradients are the driving mechanism for several phase-change phenomena such as condensation dry zones, interdroplet ice bridging, dry zones around ice, and frost halos. Despite the fundamental nature of the underlying pressure gradients, the majority of studies on these emerging phenomena have been primarily empirical. Using classical nucleation theory and Becker-Döring embryo formation kinetics, here we calculate the pressure field for all possible modes of condensation and desublimation in order to gain fundamental insight into how pressure gradients govern the behavior of dry zones, condensation frosting, and frost halos. Our findings reveal that in a variety of phase-change systems the thermodynamically favorable mode of nucleation can switch between condensation and desublimation depending upon the temperature and wettability of the surface. The calculated pressure field is used to model the length of a dry zone around liquid or ice droplets over a broad parameter space. The long-standing question of whether the vapor pressure at the interface of growing frost is saturated or supersaturated is resolved by considering the kinetics of interdroplet ice bridging. Finally, on the basis of theoretical calculations, we propose that there exists a new mode of frost halo that is yet to be experimentally observed; a bimodal phase map is developed, demonstrating its dependence on the temperature and wettability of the underlying substrate. We hope that the model and predictions contained herein will assist future efforts to exploit localized vapor pressure gradients for the design of spatially controlled or antifrosting phase-change systems.

Simulation of argon response and light detection in the DarkSide-50 dual phase TPC

Energy Technology Data Exchange (ETDEWEB)

Agnes, P.; Albuquerque, I. F. M.; Alexander, T.; Alton, A. K.; Asner, D. M.; Back, H. O.; Biery, K.; Bocci, V.; Bonfini, G.; Bonivento, W.; Bossa, M.; Bottino, B.; Budano, F.; Bussino, S.; Cadeddu, M.; Cadoni, M.; Calaprice, F.; Canci, N.; Candela, A.; Caravati, M.; Cariello, M.; Carlini, M.; Catalanotti, S.; Cataudella, V.; Cavalcante, P.; Chepurnov, A.; Cicalò, C.; Cocco, A. G.; Covone, G.; D' Angelo, D.; D' Incecco, M.; Davini, S.; de Candia, A.; Cecco, S. De; Deo, M. De; Filippis, G. De; Vincenzi, M. De; Derbin, A. V.; Rosa, G. De; Devoto, A.; Eusanio, F. Di; Pietro, G. Di; Dionisi, C.; Edkins, E.; Empl, A.; Fan, A.; Fiorillo, G.; Fomenko, K.; Franco, D.; Gabriele, F.; Galbiati, C.; Giagu, S.; Giganti, C.; Giovanetti, G. K.; Goretti, A. M.; Granato, F.; Gromov, M.; Guan, M.; Guardincerri, Y.; Hackett, B. R.; Herner, K.; Hughes, D.; Humble, P.; Hungerford, E. V.; Ianni, An.; James, I.; Johnson, T. N.; Keeter, K.; Kendziora, C. L.; Koh, G.; Korablev, D.; Korga, G.; Kubankin, A.; Li, X.; Lissia, M.; Loer, B.; Longo, G.; Ma, Y.; Machado, A. A.; Machulin, I. N.; Mandarano, A.; Mari, S. M.; Maricic, J.; Martoff, C. J.; Meyers, P. D.; Milincic, R.; Monte, A.; Mount, B. J.; Muratova, V. N.; Musico, P.; Napolitano, J.; Agasson, A. Navrer; Oleinik, A.; Orsini, M.; Ortica, F.; Pagani, L.; Pallavicini, M.; Pantic, E.; Pelczar, K.; Pelliccia, N.; Pocar, A.; Pordes, S.; Pugachev, D. A.; Qian, H.; Randle, K.; Razeti, M.; Razeto, A.; Reinhold, B.; Renshaw, A. L.; Rescigno, M.; Riffard, Q.; Romani, A.; Rossi, B.; Rossi, N.; Sablone, D.; Sands, W.; Sanfilippo, S.; Savarese, C.; Schlitzer, B.; Segreto, E.; Semenov, D. A.; Singh, P. N.; Skorokhvatov, M. D.; Smirnov, O.; Sotnikov, A.; Stanford, C.; Suvorov, Y.; Tartaglia, R.; Testera, G.; Tonazzo, A.; Trinchese, P.; Unzhakov, E. V.; Verducci, M.; Vishneva, A.; Vogelaar, B.; Wada, M.; Walker, S.; Wang, H.; Wang, Y.; Watson, A. W.; Westerdale, S.; Wilhelmi, J.; Wojcik, M. M.; Xiang, X.; Xiao, X.; Yang, C.; Ye, Z.; Zhu, C.; Zuzel, G.

2017-10-01

Geant4-based Monte Carlo package named G4DS has been developed to simulate the response of DarkSide-50, an experiment operating since 2013 at LNGS, designed to detect WIMP interactions in liquid argon. In the process of WIMP searches, DarkSide-50 has achieved two fundamental milestones: the rejection of electron recoil background with a power of ~10^7, using the pulse shape discrimination technique, and the measurement of the residual 39Ar contamination in underground argon, ~3 orders of magnitude lower with respect to atmospheric argon.

Emissive spectra of shock-heated argon

International Nuclear Information System (INIS)

Tang Jingyou; Gu Yan; Peng Qixian; Bai Yulin; Li Ping

2003-01-01

To study the radiant properties of argon under weak shock compression, an aluminum target filled with gaseous argon at ambient states was impacted by a tungsten alloy projectile which was launched from a two-stage light gun to 2.00 km/s. The radiant signals of single shock-compressed argon were recorded by a six-channel pyrometer and oscilloscopes, which varied with time linearly for the five channels from 405 nm to 700 nm and exponentially for the channel 800 nm, and the corresponding velocity of shock wave was determined to be 4.10 ± 0.09 km/s. By the present experiment, it has been shown that the absorbability of the shock-heated argon is low for visual light and the optical depths of argon gas turn from thin to thick as wavelengths gradually increase. The time-resolved spectra in the rising-front of the radiant signal in the re-shocked argon were recorded by means of an OMA, and strong emissive spectrum bands near 450 nm light-wave length but no linear spectrum were found. The emissive spectrum properties of shock-compression argon were qualitatively explained by the state parameters and ionization degree

NBS measurement system for natural argon-37

International Nuclear Information System (INIS)

Currie, L.A.; Lindstrom, R.M.

1973-01-01

A project to determine the cosmic-ray production rate and the natural levels of 35-day half-life 37 Ar in the atmosphere has been underway at the National Bureau of Standards for about the past year. The prime objective of this project is to determine the spatial dependence of 37 Ar production in the atmosphere, and the spatial distribution of the naturally-produced 37 Ar (observed concentrations). The results of this study are to be used, in cooperation with L. Machta (National Oceanographic and Atmospheric Administration), to derive information about atmospheric mixing. The purpose of this communication, however, is to present a general description of the various components of the measurement system. As the lowest concentrations of interest are but approximately equal to 10 -3 dpm ( 37 Ar)/l-Ar, very high sensitivity measurement techniques are required. Among the techniques which we have adopted are: quantitative separation of the noble gases from about 1 m 3 of air, using a CaC 2 reactor; gas chromatographic separation of the argon fraction; isotopic enrichment (by a factor of approximately equal to 100) of purified argon; use of specially selected low-level gas proportional counters together with massive shielding and anticoincidence meson cancellation; and the application of pulse discrimination based upon both amplitude (energy) and pulse shape. Finally, on-line computer techniques are being applied for data acquisition and system control

Restoring sedges and mosses into frost heaving iron fens, San Juan Mountains, Colorado

Directory of Open Access Journals (Sweden)

R.A. Chimner

2011-08-01

Full Text Available Rare iron fens in the San Juan Mountains of Colorado are frequently in poor condition due to mining, roads and ditches, which have left much of the fen completely bare of vegetation. Natural revegetation is slow to occur in the bare areas because of severe frost heave in the cold mountain climate. Therefore, experimental revegetation plots were conducted in a factorial design with mulching and no mulching, crossed with moss diaspores, sedge transplants, and moss and sedge combined. Mulching influenced surface soil temperatures by reducing the midday highs and increasing the night-time lows, which decreased the frequency and amount of frost heave. Peat moisture also modified frost heave, with the greatest frost heaving occurring near 75 % peat moisture content (water table 10–20 cm below the surface and the least when soils were either wetter or drier. Moss survival was dependent on mulch, with no moss surviving in plots without mulch. Mulching also increased sedge transplant survival. In summary, mulching significantly increased the success of vegetation restoration efforts for frost heave areas in mountain fens.

Micrometeorological and Thermal Control of Frost Flower Growth and Decay on Young Sea Ice

DEFF Research Database (Denmark)

Galley, Ryan J.; Else, Brent G. T.; Geilfus, Nicolas-Xavier

2015-01-01

-wave radiation balance at the surface. The observed crystal habits of the frost flowers were long needles, betraying their origin from the vapour phase at temperatures between -20°C and -30°C. After a night of growth, frost flowers decayed associated with increased solar radiation, a net surface radiation...... and the physical and thermal properties of the sea ice and atmosphere that form, decay and destroy frost flowers on young sea ice. Frost flower formation occurred during a high-pressure system that caused air temperatures to drop to -30°C, with relative humidity of 70% (an under saturated atmosphere), and very...

Frost heave in helium and other substances

International Nuclear Information System (INIS)

Dash, J.G.

1992-01-01

A thermomolecular pressure associated with a thermal gradient produces the phenomenon known as 'frost heave' in moisture-containing frozen ground. Thermomolecular pressures can occur in any material. As described here it is known that frost heave or thermomolecular pressures can be exhibited by any material undergoing 'premelting,' where liquid exists at temperatures below the normal solid-liquid phase boundary. Yet, the recent work on 4 He [Hiroi, et a., Phys. Rev.B 40, 6581 (1989)] is the first published study of thermomolecular pressure in nonaqueous material. The striking prominence of the effect presents advantages of further applications of thermomolecular pressure for fundamental research. This paper describes the phenomenon, outlines the theory and discusses some possible static and dynamic studies of quantum liquids

Marker-trait association analysis of frost tolerance of 672 worldwide pea (Pisum sativum L.) collections.

Science.gov (United States)

Liu, Rong; Fang, Li; Yang, Tao; Zhang, Xiaoyan; Hu, Jinguo; Zhang, Hongyan; Han, Wenliang; Hua, Zeke; Hao, Junjie; Zong, Xuxiao

2017-07-19

Frost stress is one of the major abiotic stresses causing seedling death and yield reduction in winter pea. To improve the frost tolerance of pea, field evaluation of frost tolerance was conducted on 672 diverse pea accessions at three locations in Northern China in three growing seasons from 2013 to 2016 and marker-trait association analysis of frost tolerance were performed with 267 informative SSR markers in this study. Sixteen accessions were identified as the most winter-hardy for their ability to survive in all nine field experiments with a mean survival rate of 0.57, ranging from 0.41 to 0.75. Population structure analysis revealed a structured population of two sub-populations plus some admixtures in the 672 accessions. Association analysis detected seven markers that repeatedly had associations with frost tolerance in at least two different environments with two different statistical models. One of the markers is the functional marker EST1109 on LG VI which was predicted to co-localize with a gene involved in the metabolism of glycoproteins in response to chilling stress and may provide a novel mechanism of frost tolerance in pea. These winter-hardy germplasms and frost tolerance associated markers will play a vital role in marker-assisted breeding for winter-hardy pea cultivar.

Preparing for climate change: Breeding frost tolerant potatoes adapted to Andean Highlands especially the Altiplano

Science.gov (United States)

Frost can have a devastating impact on potato production since most cultivated potatoes are very sensitive to frost and are severely damaged at air temperatures below -2 or -3 C. In the Altiplano of Peru and Bolivia over 60,000 hectares of potato production is impacted by frost. It has been estimate...

Measuring soil frost depth in forest ecosystems with ground penetrating radar

Science.gov (United States)

John R. Butnor; John L. Campbell; James B. Shanley; Stanley. Zarnoch

2014-01-01

Soil frost depth in forest ecosystems can be variable and depends largely on early winter air temperatures and the amount and timing of snowfall. A thorough evaluation of ecological responses to seasonally frozen ground is hampered by our inability to adequately characterize the frequency, depth, duration and intensity of soil frost events. We evaluated the use of...

Effect of snow cover on soil frost penetration

Science.gov (United States)

Rožnovský, Jaroslav; Brzezina, Jáchym

2017-12-01

Snow cover occurrence affects wintering and lives of organisms because it has a significant effect on soil frost penetration. An analysis of the dependence of soil frost penetration and snow depth between November and March was performed using data from 12 automated climatological stations located in Southern Moravia, with a minimum period of measurement of 5 years since 2001, which belong to the Czech Hydrometeorological institute. The soil temperatures at 5 cm depth fluctuate much less in the presence of snow cover. In contrast, the effect of snow cover on the air temperature at 2 m height is only very small. During clear sky conditions and no snow cover, soil can warm up substantially and the soil temperature range can be even higher than the range of air temperature at 2 m height. The actual height of snow is also important - increased snow depth means lower soil temperature range. However, even just 1 cm snow depth substantially lowers the soil temperature range and it can therefore be clearly seen that snow acts as an insulator and has a major effect on soil frost penetration and soil temperature range.

Ionization relaxation in shock-heated krypton-argon mixtures

International Nuclear Information System (INIS)

Ezumi, Hiromichi; Kawamura, Masahiko; Yokota, Toshiaki.

1977-01-01

The ionization relaxation processes behind shock waves in pure krypton and krypton-argon mixtures have been investigated using a Mach-Zehnder interferometer technique. The incident shock velocity was fixed in the neighborhood of Us=2800 m/sec, and the initial pressure was fixed at 0.95 Torr. The experimental results were compared with theoretical values based on the two-step collisional ionization model taking into account of the wall boundary-layer effect. The slope constants of excitation cross section against relative kinetic energy between krypton atom-atom collisions, krypton atom-electron collisions, and krypton-argon atom-atom collisions were determined to be 4.2 x 10 -19 cm 2 /eV, 1.2 x 10 -17 cm 2 /eV, and 4.2 x 10 -19 cm 2 /eV, respectively. (auth.)

Estimating winter survival of winter wheat by simulations of plant frost tolerance

NARCIS (Netherlands)

Bergjord Olsen, A.K.; Persson, T.; Wit, de A.; Nkurunziza, L.; Sindhøj, E.; Eckersten, H.

2018-01-01

Based on soil temperature, snow depth and the grown cultivar's maximum attainable level of frost tolerance (LT50c), the FROSTOL model simulates development of frost tolerance (LT50) and winter damage, thereby enabling risk calculations for winter wheat survival. To explore the accuracy of this

LArGe. A liquid argon scintillation veto for GERDA

International Nuclear Information System (INIS)

Heisel, Mark

2011-01-01

LArGe is a GERDA low-background test facility to study novel background suppression methods in a low-background environment, for possible applications in the GERDA experiment. GERDA searches for the neutrinoless double-beta decay in 76 Ge, by operating naked germanium detectors submersed into 65 m 3 of liquid argon. Similarly, LArGe runs Ge-detectors in 1 m 3 (1.4 tons) of liquid argon, which in addition is instrumented with photomultipliers to detect argon scintillation light. The light is used in anti-coincidence with the germanium detectors, to effectively suppress background events that deposit energy in the liquid argon. This work adresses the design, construction, and commissioning of LArGe. The background suppression efficiency has been studied in combination with a pulse shape discrimination (PSD) technique for various sources, which represent characteristic backgrounds to GERDA. Suppression factors of a few times 10 3 have been achieved. First background data of LArGe (without PSD) yield a background index of (0.12-4.6).10 -2 cts/(keV.kg.y) (90% c.l.), which is at the level of the Gerda phase I design goal. Furthermore, for the first time we measure the natural 42 Ar abundance (in parallel to Gerda), and have indication for the 2νββ-decay in natural germanium. (orig.)

LArGe. A liquid argon scintillation veto for GERDA

Energy Technology Data Exchange (ETDEWEB)

Heisel, Mark

2011-04-13

LArGe is a GERDA low-background test facility to study novel background suppression methods in a low-background environment, for possible applications in the GERDA experiment. GERDA searches for the neutrinoless double-beta decay in {sup 76}Ge, by operating naked germanium detectors submersed into 65 m{sup 3} of liquid argon. Similarly, LArGe runs Ge-detectors in 1 m{sup 3} (1.4 tons) of liquid argon, which in addition is instrumented with photomultipliers to detect argon scintillation light. The light is used in anti-coincidence with the germanium detectors, to effectively suppress background events that deposit energy in the liquid argon. This work adresses the design, construction, and commissioning of LArGe. The background suppression efficiency has been studied in combination with a pulse shape discrimination (PSD) technique for various sources, which represent characteristic backgrounds to GERDA. Suppression factors of a few times 10{sup 3} have been achieved. First background data of LArGe (without PSD) yield a background index of (0.12-4.6).10{sup -2} cts/(keV.kg.y) (90% c.l.), which is at the level of the Gerda phase I design goal. Furthermore, for the first time we measure the natural {sup 42}Ar abundance (in parallel to Gerda), and have indication for the 2{nu}{beta}{beta}-decay in natural germanium. (orig.)

Frost Multidimensional Perfectionism Scale: the portuguese version

Directory of Open Access Journals (Sweden)

Ana Paula Monteiro Amaral

2013-01-01

Full Text Available BACKGROUND: The Frost Multidimensional Perfectionism Scale is one of the most world widely used measures of perfectionism. OBJECTIVE: To analyze the psychometric properties of the Portuguese version of the Frost Multidimensional Perfectionism Scale. METHODS: Two hundred and seventeen (178 females students from two Portuguese Universities filled in the scale, and a subgroup (n = 166 completed a retest with a four weeks interval. RESULTS: The scale reliability was good (Cronbach alpha = .857. Corrected item-total correlations ranged from .019 to .548. The scale test-retest reliability suggested a good temporal stability with a test-retest correlation of .765. A principal component analysis with Varimax rotation was performed and based on the Scree plot, two robust factorial structures were found (four and six factors. The principal component analyses, using Monte Carlo PCA for parallel analyses confirmed the six factor solution. The concurrent validity with Hewitt and Flett MPS was high, as well as the discriminant validity of positive and negative affect (Profile of Mood Stats-POMS. DISCUSSION: The two factorial structures (of four and six dimensions of the Portuguese version of Frost Multidimensional Perfectionism Scale replicate the results from different authors, with different samples and cultures. This suggests this scale is a robust instrument to assess perfectionism, in several clinical and research settings as well as in transcultural studies.

Climate Change and Crop Exposure to Adverse Weather: Changes to Frost Risk and Grapevine Flowering Conditions.

Science.gov (United States)

Mosedale, Jonathan R; Wilson, Robert J; Maclean, Ilya M D

2015-01-01

The cultivation of grapevines in the UK and many other cool climate regions is expected to benefit from the higher growing season temperatures predicted under future climate scenarios. Yet the effects of climate change on the risk of adverse weather conditions or events at key stages of crop development are not always captured by aggregated measures of seasonal or yearly climates, or by downscaling techniques that assume climate variability will remain unchanged under future scenarios. Using fine resolution projections of future climate scenarios for south-west England and grapevine phenology models we explore how risks to cool-climate vineyard harvests vary under future climate conditions. Results indicate that the risk of adverse conditions during flowering declines under all future climate scenarios. In contrast, the risk of late spring frosts increases under many future climate projections due to advancement in the timing of budbreak. Estimates of frost risk, however, were highly sensitive to the choice of phenology model, and future frost exposure declined when budbreak was calculated using models that included a winter chill requirement for dormancy break. The lack of robust phenological models is a major source of uncertainty concerning the impacts of future climate change on the development of cool-climate viticulture in historically marginal climatic regions.

Transcriptome profiling of fully open flowers in a frost-tolerant almond genotype in response to freezing stress.

Science.gov (United States)

Hosseinpour, Batool; Sepahvand, Sadegh; Kamali Aliabad, Kazem; Bakhtiarizadeh, MohammadReza; Imani, Ali; Assareh, Reza; Salami, Seyed Alireza

2018-02-01

Spring frost is a major limiting abiotic stress for the cultivation of almonds [Prunus dulcis (Mill.)] in Mediterranean areas or the Middle East. Spring frost, in particular, damages almond fully open flowers, resulting to significant reduction in yield. Little is known about the genetic factors expressed after frost stress in Prunus spp. as well as in almond fully open flowers. Here, we provide the molecular signature of pistils of fully open flowers from a frost-tolerant almond genotype. The level of frost tolerance in this genotype was determined for all three flowering stages and was confirmed by comparing it to two other cultivars using several physiological analyses. Afterwards, comprehensive expression profiling of genes expressed in fully open flowers was performed after being exposed to frost temperatures (during post-thaw period). Clean reads, 27,104,070 and 32,730,772, were obtained for non-frost-treated and frost-treated (FT) libraries, respectively. A total of 62.24 Mb was assembled, generating 50,896 unigenes and 66,906 transcripts. Therefore, 863 upregulated genes and 555 downregulated genes were identified in the FT library. Functional annotation showed that most of the upregulated genes were related to various biological processes involved in responding to abiotic stress. For the first time, a highly expressed cold-shock protein was identified in the reproductive organ of fruit trees. The expression of six genes was validated by RT-PCR. As the first comprehensive analysis of open flowers in a frost-tolerant almond genotype, this study represents a key step toward the molecular breeding of fruit tree species for frost tolerance.

Temporal and spatial variability of frost-free seasons in the Great Lakes region of the United States

Science.gov (United States)

Lejiang Yu; Shiyuan Zhong; Xindi Bian; Warren E. Heilman; Jeffrey A. Andresen

2014-01-01

The frequency and timing of frost events and the length of the growing season are critical limiting factors in many human and natural ecosystems. This study investigates the temporal and spatial variability of the date of last spring frost (LSF), the date of first fall frost (FFF), and the length of the frost-free season (FFS) in the Great Lakes region of the United...

Evaluation of the impact of frost resistances on potential altitudinal limit of trees.

Science.gov (United States)

Charrier, Guillaume; Cochard, Hervé; Améglio, Thierry

2013-09-01

Winter physiology of woody plants is a key issue in temperate biomes. Here, we investigated different frost resistance mechanisms on 1-year-old branches of 11 European tree species from November until budburst: (i) frost hardiness of living cells (by electrolyte leakage method), (ii) winter embolism sensitivity (by percentage loss of conductivity: PLC) and (iii) phenological variation of budburst (by thermal time to budburst). These ecophysiological traits were analyzed according to the potential altitudinal limit, which is highly related to frost exposure. Seasonal frost hardiness and PLC changes are relatively different across species. Maximal PLC observed in winter (PLCMax) was the factor most closely related to potential altitudinal limit. Moreover, PLCMax was related to the mean hydraulic diameter of vessels (indicating embolism sensitivity) and to osmotic compounds (indicating ability of living cells to refill xylem conducting elements). Winter embolism formation seems to be counterbalanced by active refilling from living cells. These results enabled us to model potential altitudinal limit according to three of the physiological/anatomical parameters studied. Monitoring different frost resistance strategies brings new insights to our understanding of the altitudinal limits of trees.

Predicting forest dieback in Maine, USA: a simple model based on soil frost and drought

Science.gov (United States)

Allan N.D. Auclair; Warren E. Heilman; Blondel. Brinkman

2010-01-01

Tree roots of northern hardwoods are shallow rooted, winter active, and minimally frost hardened; dieback is a winter freezing injury to roots incited by frost penetration in the absence of adequate snow cover and exacerbated by drought in summer. High soil water content greatly increases conductivity of frost. We develop a model based on the sum of z-scores of soil...

Frost hardiness of mycorrhizal and non-mycorrhizal Scots pine under two fertilization treatments.

Science.gov (United States)

Korhonen, Anna; Lehto, Tarja; Repo, Tapani

2015-07-01

Survival and functioning of mycorrhizal associations at low temperatures are not known well. In an earlier study, ectomycorrhizas did not affect the frost hardiness of Scots pine (Pinus sylvestris L.) roots, but here we studied whether differential nutrient availability would change the result and additionally, alter frost hardiness aboveground. The aim in this experiment was to compare the frost hardiness of roots and needles of mycorrhizal (Hebeloma sp.) and non-mycorrhizal Scots pine seedlings raised using two fertilization treatments and two cold-hardening regimes. The fertilization treatments were low (LF) and high (HF) application of a complete nutrient solution. Three hundred mycorrhizal and non-mycorrhizal seedlings were cultivated in growth chambers in four blocks for 16 weeks. For the first 9 weeks, the seedlings grew in long-day and high-temperature (LDHT) with low fertilization and then they were raised for 3 weeks in LDHT with either low or high fertilization. After this, half of the plants in each treatment combination remained in LDHT, and half were transferred to short-day and low-temperature (SDLT) conditions to cold acclimatize. The frost hardiness of the roots and needles was assessed using controlled freezing tests followed by electrolyte leakage tests (REL). Mycorrhizal roots were slightly more frost hardy than non-mycorrhizal roots, but only in the growing-season conditions (LDHT) in low-nutrient treatment. In LDHT and LF, the frost hardiness of the non-mycorrhizal roots was about -9 °C, and that of the non-mycorrhizal HF roots and the mycorrhizal roots in both fertilization levels was about -11 °C. However, no difference was found in the roots within the SDLT regime, and in needles, there was no difference between mycorrhizal and fertilization treatments. The frost hardiness of needles increased by SDLT treatment, being -8.5 and -14.1 °C in LDHT and SDLT, respectively. The dry mass of roots, stems, and needles was lower in LF than in

Designing a Frost Forecasting Service for Small Scale Tea Farmers in East Africa

Science.gov (United States)

Adams, E. C.; Nyaga, J. W.; Ellenburg, W. L.; Limaye, A. S.; Mugo, R. M.; Flores Cordova, A. I.; Irwin, D.; Case, J.; Malaso, S.; Sedah, A.

2017-12-01

Kenya is the third largest tea exporter in the world, producing 10% of the world's black tea. Sixty percent of this production occurs largely by small scale tea holders, with an average farm size of 1.04 acres, and an annual net income of 1,075. According to a recent evaluation, a typical frost event in the tea growing region causes about 200 dollars in losses which can be catastrophic for a small holder farm. A 72-hour frost forecast would provide these small-scale tea farmers with enough notice to reduce losses by approximately $80 annually. With this knowledge, SERVIR, a joint NASA-USAID initiative that brings Earth observations for improved decision making in developing countries, sought to design a frost monitoring and forecasting service that would provide farmers with enough lead time to react to and protect against a forecasted frost occurrence on their farm. SERVIR Eastern and Southern Africa, through its implementing partner, the Regional Centre for Mapping of Resources for Development (RCMRD), designed a service that included multiple stakeholder engagement events whereby stakeholders from the tea industry value chain were invited to share their experiences so that the exact needs and flow of information could be identified. This unique event allowed enabled the design of a service that fit the specifications of the stakeholders. The monitoring service component uses the MODIS Land Surface Temperature product to identify frost occurrences in near-real time. The prediction component, currently under testing, uses the 2-m air temperature, relative humidity, and 10-m wind speed from a series of high-resolution Weather Research and Forecasting (WRF) numerical weather prediction model runs over eastern Kenya as inputs into a frost prediction algorithm. Accuracy and sensitivity of the algorithm is being assessed with observations collected from the farmers using a smart phone app developed specifically to report frost occurrences, and from data shared through

Charge transfer cross-sections of argon ions colliding on argon atoms

International Nuclear Information System (INIS)

Aubert, J.; Bliman, S.; Chan-Tung, N.; Geller, R.; Jacquot, B.; Van Houtte, D.

1980-04-01

A device has been built to measure charge changing cross-sections of Argon ions colliding on argon atoms. It consists of an E.C.R. ion source (Micromafios) that delivers argon ions up to charge + 13. The ion source potential may be varied from 1 up to 10 kVolts. A first magnet is used to charge analyze the extracted beam. For a given separated charge state, the ion beam is passed in a collision cell whose pressure may be varied. The ions undergoing collisions on the target are analyzed by a second magnet and collected. The pressure is varied in the collision cell in order to check that the single collision condition is satisfied. It is shown that the ions do two types of collisions: charge exchange and stripping whose cross-sections are measured. Interpretation of charge exchange is proposed along yet classic theoretical approaches. As to stripping no available theory allows interpretation

Effect of argon addition into oxygen atmosphere on YBCO thin films deposition

International Nuclear Information System (INIS)

Mozhaev, P. B.; Borisenko, I. V.; Ovsyannikov, G. A.; Kuehle, A.; Bindslev-Hansen, J.; Johannes, L.; Skov, J. L.

2002-01-01

Multicomponent nature of the YBa 2 Cu 3 O x (YBCO) high-temperature superconductor makes difficult fabrication of smooth thin films: every local deviation from stoichiometry can result in seeding of a non-superconducting oxide particle. High density of such particles on typical YBCO thin film surface, however, presumes overall non-stoichiometry of the film. Such an effect can result from (i) non-uniform material transport from target to substrate, and (ii) re-evaporation or re-sputtering from the growing film surface. The first reason is more usual for laser ablation deposition technique, the second is typical for long sputtering deposition processes. Substitution of oxygen with argon in the deposition atmosphere improves surface quality of YBCO thin films deposited both by laser ablation and DC-sputtering at high pressure techniques. In the first case, the ablated species are scattered different ways in the oxygen atmosphere. Addition of argon decreases the inelastic scattering of barium; the proper part of Ar in the deposition atmosphere makes scattering and, hence, transport of all atoms uniform. The YBCO films deposited by DC-sputtering at high pressure technique are Ba-deficient also, but the reason is re-sputtering of Ba from the growing film as a result of negative oxygen ions bombardment. Such bombardment can lead also to chemical interaction of the deposited material with the substrate, as in the case of deposition of YBCO thin film on the CeO 2 buffer layer on sapphire. Substitution of oxygen with argon not only suppresses ion bombardment of the film, but also increases discharge stability due to presence of positive Ar + ions. The limiting factor of argon substitution is sufficient oxygenation of the growing oxide film. When oxygen partial pressure is too small, the superconducting quality of the YBCO thin film decreases and such a decrease cannot be overcome by prolonged oxygenation after deposition. (Authors)

Frost Damage Detection in Sugarcane Crop Using Modis Images and Srtm Data

Science.gov (United States)

Rudorff, B.; Alves de Aguiar, D.; Adami, M.

2011-12-01

Brazil is the largest world producer of sugarcane which is used to produce almost equal proportions of either sugar (food) or ethanol (biofuel). In recent years sugarcane crop production has increased fast to meet the growing market demand for sugar and ethanol. This increase has been mainly due to expansion in crop area, but sugarcane production is also subjected to several factors that influence both the agricultural crop yield (tons of stalks/ha) and the industrial yield (kg of sugar/ton of stalks). Sugarcane is a semi-perennial crop that experiences major growth during spring and summer seasons with large demands for water and high temperatures to produce good stalk formation (crop yield). The harvest is performed mainly during fall and winter seasons when water availability and temperature should be low in order to accumulate sucrose in the stalks (industrial yield). These favorable climatic conditions for sugarcane crop are found in several regions in Brazil, particularly in São Paulo state, which is the major sugarcane producer in Brazil being responsible for almost 60% of its production. Despite the favorable climate in São Paulo state there is a certain probability of frost occurrence from time to time that has a negative impact on sugarcane crop, particularly on industrial yield, reducing the amount of sugar in the stalks; having consequences on price increase and product shortage. To evaluate the impact of frost on sugarcane crop, in the field, on a state level, is not a trivial task; however, this information is relevant due to its direct impact on the consumer market. Remote sensing images allow a synoptic view and present great potential to monitor large sugarcane plantations as has been done since 2003 in São Paulo state by the Canasat Project with Landsat type images (http://www.dsr.inpe.br/laf/canasat/en/). Images acquired from sensors with high temporal resolution such as MODIS (Moderate-Resolution Imaging Spectroradiometer) present the

Numerical Model on Frost Height of Round Plate Fin Used for Outdoor Heat Exchanger of Mobile Electric Heat Pumps

Directory of Open Access Journals (Sweden)

Moo-Yeon Lee

2012-01-01

Full Text Available The objective of this study is to provide the numerical model for prediction of the frost growth of the round plate fin for the purpose of using it as a round plate fin-tube heat exchanger (evaporator under frosting conditions. In this study, numerical model was considering the frost density change with time, and it showed better agreement with experimental data of Sahin (1994 than that of the Kim model (2004 and the Jonse and Parker model (1975. This is because the prediction on the frost height with time was improved by using the frost thermal conductivity reflecting the void fraction and density of ice crystal with frost growth. Therefore, the developed numerical model could be used for frosting performance prediction of the round plate fin-tube heat exchanger.

Effect of Latent Heat Released by Freezing Droplets during Frost Wave Propagation.

Science.gov (United States)

Chavan, Shreyas; Park, Deokgeun; Singla, Nitish; Sokalski, Peter; Boyina, Kalyan; Miljkovic, Nenad

2018-05-21

Frost spreads on nonwetting surfaces during condensation frosting via an interdroplet frost wave. When a supercooled condensate water droplet freezes on a hydrophobic or superhydrophobic surface, neighboring droplets still in the liquid phase begin to evaporate. Two possible mechanisms govern the evaporation of neighboring water droplets: (1) The difference in saturation pressure of the water vapor surrounding the liquid and frozen droplets induces a vapor pressure gradient, and (2) the latent heat released by freezing droplets locally heats the substrate, leading to evaporation of nearby droplets. The relative significance of these two mechanisms is still not understood. Here, we study the significance of the latent heat released into the substrate by freezing droplets, and its effect on adjacent droplet evaporation, by studying the dynamics of individual water droplet freezing on aluminum-, copper-, and glass-based hydrophobic and superhydrophobic surfaces. The latent heat flux released into the substrate was calculated from the measured droplet sizes and the respective freezing times ( t f ), defined as the time from initial ice nucleation within the droplet to complete droplet freezing. To probe the effect of latent heat release, we performed three-dimensional transient finite element simulations showing that the transfer of latent heat to neighboring droplets is insignificant and accounts for a negligible fraction of evaporation during microscale frost wave propagation. Furthermore, we studied the effect of substrate thermal conductivity on the transfer of latent heat transfer to neighboring droplets by investigating the velocity of ice bridge formation. The velocity of the ice bridge was independent of the substrate thermal conductivity, indicating that adjacent droplet evaporation during condensation frosting is governed solely by vapor pressure gradients. This study not only provides key insights into the individual droplet freezing process but also

Observations of Chemical Composition in Frost Flower Growth Process and Their Implication in Aerosol Production and Bromine Activation Chemistry

Science.gov (United States)

Alvarez-Aviles, L.; Simpson, W. R.; Douglas, T. A.; Sturm, M.; Perovich, D. K.

2006-12-01

Frost flowers are believed to be responsible for most of the salt aerosol and possibly the bromine in the gas phase during springtime in Polar Regions. Frost flowers are vapor deposited ice crystals that form on new forming sea ice and wick brine from the sea-ice surface resulting in high salinities. We propose a conceptual model of frost flower growth and chemical fractionation using chemical analysis to support this model. We also consider how the chemical composition of frost flowers can tell us about the role of frost flowers in bromine activation and aerosol production. Our conceptual model is centered in two important events that occur when sea ice grows and the ice surface temperature gets colder. Brine on the sea-ice surface is drawn up the frost flower by capillary forces, therefore the high salinity values found. Secondarily salt hydrates begin to precipitate at certain temperatures. These precipitation reactions modify the chemical composition of the frost flowers and residual brine, and are the main topic of this research. We found variability and generally depletion of sulfate as compared to sea-water composition in most of the mature frost flowers. This result is in agreement with the literature, which proposes the depletion in sulfate occurs because mirabilite (Na2SO4 · 10H2O) precipitates before the brine is wicked. The observation of some slightly sulfate-enhanced samples in addition to depleted samples indicates that the brine/frost flower environment is the location where mirabilite precipitation and separation from residual brine occurs. Frost flowers bromide enhancement factors are all, within analytical limits, identical to sea water, although nearby snow is depleted in bromide. Because of the high salt concentrations in frost flowers, significant bromine activation could occur from frost flowers without being detected by this measurement. However, if all bromide activation occurred on frost flowers, and frost flowers are not depleted in

Simplified fuel cycle tritium inventory model for systems studies -- An illustrative example with an optimized cryopump exhaust system

International Nuclear Information System (INIS)

Kuan, W.; Ho, S.K.

1995-01-01

It is desirable to incorporate safety constraints due to fuel cycle tritium inventories into tokamak reactor design optimization. An optimal scenario to minimize tritium inventories without much degradation of plasma performance can be defined for each tritium processing component. In this work, the computer code TRUFFLES is used exclusively to obtain numerical data for a simplified model to be used for systems studies. As an illustration, the cryopump plasma exhaust subsystem is examined in detail for optimization purposes. This optimization procedure will then be used to further reduce its window of operation and provide constraints on the data used for the simplified tritium inventory model

Exogenous application of molybdenum affects the expression of CBF14 and the development of frost tolerance in wheat.

Science.gov (United States)

Al-Issawi, Mohammed; Rihan, Hail Z; Woldie, Wondwossen Abate; Burchett, Stephen; Fuller, Michael P

2013-02-01

Wheat is able to cold acclimate in response to low temperatures and thereby increase its frost tolerance and the extent of this acclimation is greater in winter genotypes compared to spring genotypes. Such up-regulation of frost tolerance is controlled by Cbf transcription factors. Molybdenum (Mo) application has been shown to enhance frost tolerance of wheat and this study aimed to investigate the effect of Mo on the development of frost tolerance in winter and spring wheat. Results showed that Mo treatment increased the expression of Cbf14 in wheat under non-acclimating condition but did not alter frost tolerance. However, when Mo was applied in conjunction with exposure of plants to low temperature, Mo increased the expression of Cbf14 and enhanced frost tolerance in both spring and winter genotypes but the effect was more pronounced in the winter genotype. It was concluded that the application of Mo could be useful in situations where enhanced frost resistance is required. Further studies are proposed to elucidate the effect of exogenous of applications of Mo on frost resistance in spring and winter wheat at different growth stages. Crown Copyright © 2012. Published by Elsevier Masson SAS. All rights reserved.

Winter Frost and Fog

Science.gov (United States)

2005-01-01

This somewhat oblique blue wide angle Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC) image shows the 174 km (108 mi) diameter crater, Terby, and its vicinity in December 2004. Located north of Hellas, this region can be covered with seasonal frost and ground-hugging fog, even in the afternoon, despite being north of 30oS. The subtle, wavy pattern is a manifestation of fog. Location near: 28oS, 286oW Illumination from: upper left Season: Southern Winter

Sand Dunes with Frost

Science.gov (United States)

2004-01-01

9 May 2004 This Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC) image shows a suite of frost-covered sand dunes in the north polar region of Mars in early spring, 2004. The dunes indicate wind transport of sand from left to right (west to east). These landforms are located near 78.1oN, 220.8oW. This picture is illuminated by sunlight from the lower left and covers an area about 3 km (1.9 mi) across.

The Liquid Argon Purity Demonstrator

Energy Technology Data Exchange (ETDEWEB)

Adamowski, M.; Carls, B.; Dvorak, E.; Hahn, A.; Jaskierny, W.; Johnson, C.; Jostlein, H.; Kendziora, C.; Lockwitz, S.; Pahlka, B.; Plunkett, R.; Pordes, S.; Rebel, B.; Schmitt, R.; Stancari, M.; Tope, T.; Voirin, E.; Yang, T.

2014-07-01

The Liquid Argon Purity Demonstrator was an R&D test stand designed to determine if electron drift lifetimes adequate for large neutrino detectors could be achieved without first evacuating the cryostat. We describe here the cryogenic system, its operations, and the apparatus used to determine the contaminant levels in the argon and to measure the electron drift lifetime. The liquid purity obtained by this system was facilitated by a gaseous argon purge. Additionally, gaseous impurities from the ullage were prevented from entering the liquid at the gas-liquid interface by condensing the gas and filtering the resulting liquid before returning to the cryostat. The measured electron drift lifetime in this test was greater than 6 ms, sustained over several periods of many weeks. Measurements of the temperature profile in the argon, to assess convective flow and boiling, were also made and are compared to simulation.

Comparison of heat pump performance using fin-and-tube and microchannel heat exchangers under frost conditions

International Nuclear Information System (INIS)

Shao, Liang-Liang; Yang, Liang; Zhang, Chun-Lu

2010-01-01

Vapor compression heat pumps are drawing more attention in energy saving applications. Microchannel heat exchangers can provide higher performance via less core volume and reduce system refrigerant charge, but little is known about their performance in heat pump systems under frosting conditions. In this study, the system performance of a commercial heat pump using microchannel heat exchangers as evaporator is compared with that using conventional finned-tube heat exchangers numerically and experimentally. The microchannel and finned-tube heat pump system models used for comparison of the microchannel and finned-tube evaporator performance under frosting conditions were developed, considering the effect of maldistribution on both refrigerant and air sides. The quasi-steady-state modeling results are in reasonable agreement with the test data under frost conditions. The refrigerant-side maldistribution is found remarkable impact on the microchannel heat pump system performance under the frost conditions. Parametric study on the fan speed and the fin density under frost conditions are conducted as well to figure out the best trade-off in the design of frost tolerant evaporators. (author)

Frost flowers on young Arctic sea ice: The climatic, chemical, and microbial significance of an emerging ice type

Science.gov (United States)

Barber, D. G.; Ehn, J. K.; Pućko, M.; Rysgaard, S.; Deming, J. W.; Bowman, J. S.; Papakyriakou, T.; Galley, R. J.; Søgaard, D. H.

2014-10-01

Ongoing changes in Arctic sea ice are increasing the spatial and temporal range of young sea ice types over which frost flowers can occur, yet the significance of frost flowers to ocean-sea ice-atmosphere exchange processes remains poorly understood. Frost flowers form when moisture from seawater becomes available to a cold atmosphere and surface winds are low, allowing for supersaturation of the near-surface boundary layer. Ice grown in a pond cut in young ice at the mouth of Young Sound, NE Greenland, in March 2012, showed that expanding frost flower clusters began forming as soon as the ice formed. The new ice and frost flowers dramatically changed the radiative and thermal environment. The frost flowers were about 5°C colder than the brine surface, with an approximately linear temperature gradient from their base to their upper tips. Salinity and δ18O values indicated that frost flowers primarily originated from the surface brine skim. Ikaite crystals were observed to form within an hour in both frost flowers and the thin pond ice. Average ikaite concentrations were 1013 µmol kg-1 in frost flowers and 1061 µmol kg-1 in the surface slush layer. Chamber flux measurements confirmed an efflux of CO2 at the brine-wetted sea ice surface, in line with expectations from the brine chemistry. Bacteria concentrations generally increased with salinity in frost flowers and the surface slush layer. Bacterial densities and taxa indicated that a selective process occurred at the ice surface and confirmed the general pattern of primary oceanic origin versus negligible atmospheric deposition.

Energy resolution in liquid argon doped with allene

International Nuclear Information System (INIS)

Ichinose, H.; Doke, T.; Masuda, K.; Shibamura, E.

1989-01-01

Studies have been made on liquid argon as detection medium with large volume and good energy and position resolution. It is advantageous to dope liquid argon with molecules with an ionization potential lower than the energy of scintillation light. In the present work, the energy resolution for 5.305MeV alpha particles is examined, and the effect of allene added to liquid argon is investigated. Some preliminary results for 976 KeV electrons are also presented. Allene is purified by two methods: (a) small-quantity purification and (b) mass purification. Three methods are tried for mixing allene with argon. Results concerning the allene purification methods, effect of allene concentration, and allene-argon mixing methods are presented. Discussion is made of the collected charge and energy resolution. It is concluded that the addition of allene to liquid argon greatly improves the energy resolution of 5.305 MeV alpha particles. The best intrinsic resolution is 1.4 percent FWHM obtained for 4 ppm allene doped liquid argon. In the case of 976 KeV electron radiation, energy resolution is not improved by adding allene to liquid argon. The best resolution is 31 KeV FWHM obtaiend for 65ppm allene doped liquid argon. (N.K.)

Frost sensitivity and nutrient status in a fertilized Norway spruce stand in Denmark

DEFF Research Database (Denmark)

Jönsson, A. M.; Ingerslev, M.; Raulund-Rasmussen, K.

2004-01-01

by an index of injury, based on conductivity measurements of ion leakage from needles. Despite fertilization, all trees indicated N, P and K deficiency. The foliage, collected in late winter, was generally not very frost sensitive, but foliage from trees with the lowest K and P status were more sensitive......The aim of this study was to assess the effect of the N, P and K status on frost sensitivity of Norway spruce needles in a fertilization experiment situated in a nutrient poor 29-year-old Picea abies stand in western Denmark. The relative difference in frost sensitivity among trees was assessed...... to frost, and the current year needles were more sensitive than the second and third year needles. The advancement of bud burst was assessed in May. Trees with a relatively high N concentration in the current year needles had a more advanced bud burst than trees with a lower N concentration, increasing...

Morning Frost in Trench Dug by Phoenix, Sol 113 (False Color)

Science.gov (United States)

2008-01-01

This image from the Surface Stereo Imager on NASA's Phoenix Mars Lander shows morning frost inside the 'Snow White' trench dug by the lander, in addition to subsurface ice exposed by use of a rasp on the floor of the trench. The camera took this image at about 9 a.m. local solar time during the 113th Martian day of the mission (Sept. 18, 2008). Bright material near and below the four-by-four set of rasp holes in the upper half of the image is water-ice exposed by rasping and scraping in the trench earlier the same morning. Other bright material especially around the edges of the trench, is frost. Earlier in the mission, when the sun stayed above the horizon all night, morning frost was not evident in the trench. This image is presented in false color that enhances the visibility of the frost. The trench is 4 to 5 centimeters (about 2 inches) deep, about 23 centimeters (9 inches) wide. Phoenix landed on a Martian arctic plain on May 25, 2008. The mission is led by the University of Arizona, Tucson, on behalf of NASA. Project management of the mission is led by NASA's Jet Propulsion Laboratory, Pasadena, Calif. Spacecraft development was by Lockheed Martin Space Systems, Denver.

COMPARISON OF THE FROST RESISTANCE OF BARLEY ...

African Journals Online (AJOL)

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immediate recovery of the photosynthetic quantum yield after freezing. Landraces which showed the highest cold tolerance were found to acclimatize best. Key words/phrases: Barley, chlorophyll fluorescence, cold acclimation, Ethiopia, frost tolerance. INTRODUCTION. Barley (Hordeum vulgare L.) is a traditional crop.

Experimental investigation of the effect of air velocity on a unit cooler under frosting condition: a case study

Science.gov (United States)

Bayrak, Ergin; Çağlayan, Akın; Konukman, Alp Er S.

2017-10-01

Finned tube evaporators are used in a wide range of applications such as commercial and industrial cold/freezed storage rooms with high traffic loading under frosting conditions. In this case study, an evaporator with an integrated fan was manufactured and tested under frosting conditions by only changing the air flow rate in an ambient balanced type test laboratory compared to testing in a wind tunnel with a more uniform flow distribution in order to detect the effect of air flow rate on frosting. During the test, operation was performed separately based on three different air flow rates. The parameters concerning test operation such as the changes of air temperature, air relative humidity, surface temperature, air-side pressure drop and refrigerant side capacity etc. were followed in detail for each air flow rate. At the same time, digital images were captured in front of the evaporator; thus, frost thicknesses and blockage ratios at the course of fan stall were determined by using an image-processing technique. Consequently, the test and visual results showed that the trendline of air-side pressure drop increased slowly at the first stage of test operations, then increased linearly up to a top point and then the linearity was disrupted instantly. This point speculated the beginning of defrost operation for each case. In addition, despite detecting a velocity that needs to be avoided, a test applied at minimum air velocity is superior to providing minimum capacity in terms of loss of capacity during test operations.

Laser-induced fluorescence measurements of argon ion velocities near the sheath boundary of an argon-xenon plasma

International Nuclear Information System (INIS)

Lee, Dongsoo; Severn, Greg; Oksuz, Lutfi; Hershkowitz, Noah

2006-01-01

The Bohm sheath criterion in single- and two-ion species plasma is studied with laser-induced fluorescence using a diode laser. Xenon is added to a low pressure unmagnetized dc hot filament argon discharge confined by surface multidipole magnetic fields. The Ar II transition at 668.614 nm is adopted for optical pumping to detect the fluorescence from the plasma and to measure the argon ion velocity distribution functions with respect to positions relative to a negatively biased boundary plate. The structures of the plasma sheath and presheath are measured by an emissive probe. The ion concentrations of the two-species in the bulk plasma are calculated from ion acoustic wave experiments. Results are compared with previous experiments of Ar-He plasmas in which the argon ions were the heavier ion species. Unlike the previous results, the argon speed is slower than its own Bohm velocity near the sheath-presheath boundary in the Ar-Xe plasma where argon ions are the lighter ion species. We argue that this result is consistent with the behaviour of the helium ion required by the generalized Bohm criterion in the previous experiments with Ar-He plasmas. Further, our results suggest that the measured argon ion speed approaches the ion sound speed of the system

Possible future changes in South East Australian frost frequency: an inter-comparison of statistical downscaling approaches

Science.gov (United States)

Crimp, Steven; Jin, Huidong; Kokic, Philip; Bakar, Shuvo; Nicholls, Neville

2018-04-01

Anthropogenic climate change has already been shown to effect the frequency, intensity, spatial extent, duration and seasonality of extreme climate events. Understanding these changes is an important step in determining exposure, vulnerability and focus for adaptation. In an attempt to support adaptation decision-making we have examined statistical modelling techniques to improve the representation of global climate model (GCM) derived projections of minimum temperature extremes (frosts) in Australia. We examine the spatial changes in minimum temperature extreme metrics (e.g. monthly and seasonal frost frequency etc.), for a region exhibiting the strongest station trends in Australia, and compare these changes with minimum temperature extreme metrics derived from 10 GCMs, from the Coupled Model Inter-comparison Project Phase 5 (CMIP 5) datasets, and via statistical downscaling. We compare the observed trends with those derived from the "raw" GCM minimum temperature data as well as examine whether quantile matching (QM) or spatio-temporal (spTimerQM) modelling with Quantile Matching can be used to improve the correlation between observed and simulated extreme minimum temperatures. We demonstrate, that the spTimerQM modelling approach provides correlations with observed daily minimum temperatures for the period August to November of 0.22. This represents an almost fourfold improvement over either the "raw" GCM or QM results. The spTimerQM modelling approach also improves correlations with observed monthly frost frequency statistics to 0.84 as opposed to 0.37 and 0.81 for the "raw" GCM and QM results respectively. We apply the spatio-temporal model to examine future extreme minimum temperature projections for the period 2016 to 2048. The spTimerQM modelling results suggest the persistence of current levels of frost risk out to 2030, with the evidence of continuing decadal variation.

Numerical analysis on the frosting performance of a fin-tube evaporator for a refrigerator

International Nuclear Information System (INIS)

Lee, Moo Yeon; Jang, Yong Hee; Kim, Yong Chan; Lee, Ho Sung

2008-01-01

The objective of this study is to provide numerical and experimental data that can be used to investigate the performance characteristics of a flat plate fin-tube evaporator in household and commercial refrigerators under frosting conditions. Computer simulations with variations of operating conditions such as air inlet temperature, relative humidity, and geometries were performed to find out optimal design parameters of a fin-tube evaporator for household and commercial refrigerators. The tube-by-tube method was used in the simulation and the frost growth model was considered under frosting conditions. The developed analytical model predicted the decreasing rates of heat transfer capacity and air flow rate ratio within ± 10% compared to the experimental results for a refrigerator under real operating conditions. As a result, the frost thickness at 3 .deg. C and 80% is increased 40% than that of -3 .deg. C and 80%, and the frost thickness at 3 .deg. C and 90% is increased 30% than that of 3 .deg. C and 60%. Accordingly, the operating time of the evaporator in the refrigerator was reduced with the increase of the decreasing rate of air flow rate ratio at each condition

Argon solubility in liquid steel

NARCIS (Netherlands)

Boom, R; Dankert, O; Van Veen, A; Kamperman, AA

2000-01-01

Experiments have been performed to establish the solubility of argon in liquid interstitial-free steel. The solubility appears to be lower than 0.1 at ppb, The results are in line with argon solubilities reported in the literature on liquid iron. Semiempirical theories and calculations based on the

Influence of argon dilution on growth and properties of hydrogenated nanocrystalline silicon films

Energy Technology Data Exchange (ETDEWEB)

Parashar, A. [Plasma Processed Materials Group, National Physical Laboratory (CSIR), Dr. K.S. Krishnan Road, New Delhi 110012 (India); Department of Physics and Astro Physics, University of Delhi, Delhi 110007 (India); Kumar, Sushil; Gope, Jhuma; Rauthan, C.M.S.; Dixit, P.N. [Plasma Processed Materials Group, National Physical Laboratory (CSIR), Dr. K.S. Krishnan Road, New Delhi 110012 (India); Hashmi, S.A. [Department of Physics and Astro Physics, University of Delhi, Delhi 110007 (India)

2010-05-15

The effect of argon concentration (66-87%) in total gaseous mixture (SiH{sub 4}+H{sub 2}+Ar) on growth and properties of hydrogenated nanocrystalline silicon films deposited by RF (13.56 MHz) PECVD technique was investigated. Raman and XRD measurements revealed increasing argon fraction favored enhancement of crystallinity, enlargement of crystallites and relaxation of strained bonds. Photoluminescence spectra of nc-Si:H films exhibited two radiative transitions in the photon energy ranges of 2.8-3.1 eV and 1.6-2.1 eV. The high energy PL peaks are attributed to surface effect of the films whereas peaks in the range of 1.6-2.1 eV are due to nanocrystallinity in the films. Argon dilution also helped enhancement of deposition rate and conductivity of the films. A film deposited at 81% of argon fraction possesses high crystallinity (75%), conductivity in the order of 10{sup -5} ({omega} cm){sup -1}, size of the crystallite (Raman=12 nm, XRD=18 nm), and low residual stress (125 MPa). (author)

Frost susceptibility of granular subbase materials contaminated by deicing chemicals

DEFF Research Database (Denmark)

Jørgensen, Anders Stuhr; Orlander, Tobias; Doré, Guy

2013-01-01

The increase in urban population in arctic areas leads to an increased demand for transportation infrastructures (such as roads and airfields) in the regions. This challenges the road constructions in terms of condition, bearing capacity and maintenance. It is believed that deicing agents used...... on roads and airfields enter the granular subbase materials and thereby makes the soil more frost-susceptible. In this project a series of isothermal frost heave tests has been carried out on granular subbase material from the runway at Kuujjuaq Airport, Québec, Canada. The tests have been carried out...

Metal stress consequences on frost hardiness of plants at northern high latitudes: a review and hypothesis

International Nuclear Information System (INIS)

Taulavuori, Kari; Prasad, M.N.V.; Taulavuori, Erja; Laine, Kari

2005-01-01

This paper reviews the potential of trace/heavy metal-induced stress to reduce plant frost hardiness at northern high latitudes. The scientific questions are first outlined prior to a brief summary of heavy metal tolerance. The concepts of plant capacity and survival adaptation were used to formulate a hypothesis, according to which heavy metal stress may reduce plant frost hardiness for the following reasons: (1) Heavy metals change membrane properties through impaired resource acquisition and subsequent diminution of the cryoprotectant pool. (2) Heavy metals change membrane properties directly through oxidative stress, i.e. an increase of active oxygen species. (3) The involved co-stress may further increase oxidative stress. (4) The risk of frost injury increases due to membrane alterations. An opposite perspective was also discussed: could metal stress result in enhanced plant frost hardiness? This phenomenon could be based on the metabolism (i.e. glutathione, polyamines, proline, heat shock proteins) underlying a possible general adaptation syndrome of stress (GAS). As a result of the review it was suggested that metal-induced stress seems to reduce rather than increase plant frost hardiness. - Metal stress may reduce plant frost hardiness

Metal stress consequences on frost hardiness of plants at northern high latitudes: a review and hypothesis

Energy Technology Data Exchange (ETDEWEB)

Taulavuori, Kari [Department of Biology, University of Oulu, PO Box 3000, FIN-90014, Oulu (Finland)]. E-mail: kari.taulavuori@oulu.fi; Prasad, M.N.V. [Department of Plant Sciences, University of Hyderabad, Hyderabad 500 046, Andhra Pradesh (India); Taulavuori, Erja [Department of Biology, University of Oulu, PO Box 3000, FIN-90014, Oulu (Finland); Laine, Kari [Department of Biology, University of Oulu, PO Box 3000, FIN-90014, Oulu (Finland)

2005-05-01

This paper reviews the potential of trace/heavy metal-induced stress to reduce plant frost hardiness at northern high latitudes. The scientific questions are first outlined prior to a brief summary of heavy metal tolerance. The concepts of plant capacity and survival adaptation were used to formulate a hypothesis, according to which heavy metal stress may reduce plant frost hardiness for the following reasons: (1) Heavy metals change membrane properties through impaired resource acquisition and subsequent diminution of the cryoprotectant pool. (2) Heavy metals change membrane properties directly through oxidative stress, i.e. an increase of active oxygen species. (3) The involved co-stress may further increase oxidative stress. (4) The risk of frost injury increases due to membrane alterations. An opposite perspective was also discussed: could metal stress result in enhanced plant frost hardiness? This phenomenon could be based on the metabolism (i.e. glutathione, polyamines, proline, heat shock proteins) underlying a possible general adaptation syndrome of stress (GAS). As a result of the review it was suggested that metal-induced stress seems to reduce rather than increase plant frost hardiness. - Metal stress may reduce plant frost hardiness.

The Argon Dark Matter Experiment

CERN Document Server

AUTHOR|(CDS)2071720

2009-01-01

The ArDM experiment, a 1 ton liquid argon TPC/Calorimeter, is designed for the detection of dark matter particles which can scatter off the spinless argon nucleus, producing nuclear recoils. These events will be discerned by their light to charge ratio, as well as the time structure of the scintillation light. The experiment is presently under construction and commissioning on surface at CERN. Cryogenic operation and light detection performance was recently confirmed in a test run of the full 1 ton liquid argon target under purely calorimetric operation and with a prototype light readout system. This note describes the experimental concept, the main detector components and presents some first results.

Argon cover gas purity control on LMFBR

Energy Technology Data Exchange (ETDEWEB)

Maeda, Hiroshi; Kobayashi, Takayoshi [PNC (Japan); Ishiyama, Satoshi [Toshiba (Japan); Motonaga, Tetsuji [Hitachi (Japan)

1987-07-01

Various control methods on chemical impurities and radioactive materials (fission products) in the primary argon gas of LMFBRs' have been studied based on experiences in Joyo and results of research and development. These results are reflected on MONJU design. On-line gas chromatographs are installed both in the Primary and in the Secondary Argon Gas Systems in JOYO. Also, chemical analysis has been done by batch sampling in JOYO. Though the rise of impurity concentration had been measured after periodical fuel exchange operation, impurity concentration has been controlled sufficiently under target control limits. In MONJU detailed design, the Rare Gas Removal and Recovery System which consisted of cryogenic distillation equipment had been eliminated and the capacity of Charcoal Beds in the Primary Argon Gas System has been improved to keep the concentration of radioactive materials sufficient low levels. The necessity to control the impurities in fresh argon gas which is supplied to the Primary Argon Gas System is now considered to keep the concentration of Kr and Xe isotopes in specified level, because their isotopes may make background rise for the Tagging Gas Failed Fuel Detection and Location System. Based on various investigations performed on sodium vapor trapping to obtain its detailed characteristics, design specifications and operating conditions of MONJU's Vapor Traps have been decided. To keep the level of radioactivity in gaseous effluents to the environment as low as reasonably achievable, the following means are now adopted in MONJU: the Primary Argon Gas System is composed of a closed recirculating path, but the exhaust gas discharged has different path after the Charcoal Beds; fresh argon gas is blown down to prevent Primary Argon Gas from releasing to the circumference during opening of the primary argon gas boundary, such as fuel exchange operations. (author)

Active background suppression with the liquid argon scintillation veto of GERDA Phase II

Science.gov (United States)

Agostini, M.; Allardt, M.; Bakalyarov, A. M.; Balata, M.; Barabanov, I.; Baudis, L.; Bauer, C.; Bellotti, E.; Belogurov, S.; Belyaev, S. T.; Benato, G.; Bettini, A.; Bezrukov, L.; Bode, T.; Borowicz, D.; Brudanin, V.; Brugnera, R.; Caldwell, A.; Cattadori, C.; Chernogorov, A.; D'Andrea, V.; Demidova, E. V.; Di Marco, N.; Domula, A.; Doroshkevich, E.; Egorov, V.; Falkenstein, R.; Frodyma, N.; Gangapshev, A.; Garfagnini, A.; Gooch, C.; Grabmayr, P.; Gurentsov, V.; Gusev, K.; Hakenmüller, J.; Hegai, A.; Heisel, M.; Hemmer, S.; Hofmann, W.; Hult, M.; Inzhechik, L. V.; Janicskó Csáthy, J.; Jochum, J.; Junker, M.; Kazalov, V.; Kihm, T.; Kirpichnikov, I. V.; Kirsch, A.; Kish, A.; Klimenko, A.; Kneißl, R.; Knöpfle, K. T.; Kochetov, O.; Kornoukhov, V. N.; Kuzminov, V. V.; Laubenstein, M.; Lazzaro, A.; Lebedev, V. I.; Lehnert, B.; Liao, H. Y.; Lindner, M.; Lippi, I.; Lubashevskiy, A.; Lubsandorzhiev, B.; Lutter, G.; Macolino, C.; Majorovits, B.; Maneschg, W.; Medinaceli, E.; Miloradovic, M.; Mingazheva, R.; Misiaszek, M.; Moseev, P.; Nemchenok, I.; Palioselitis, D.; Panas, K.; Pandola, L.; Pelczar, K.; Pullia, A.; Riboldi, S.; Rumyantseva, N.; Sada, C.; Salamida, F.; Salathe, M.; Schmitt, C.; Schneider, B.; Schönert, S.; Schreiner, J.; Schulz, O.; Schütz, A.-K.; Schwingenheuer, B.; Selivanenko, O.; Shevzik, E.; Shirchenko, M.; Simgen, H.; Smolnikov, A.; Stanco, L.; Vanhoefer, L.; Vasenko, A. A.; Veresnikova, A.; von Sturm, K.; Wagner, V.; Wegmann, A.; Wester, T.; Wiesinger, C.; Wojcik, M.; Yanovich, E.; Zhitnikov, I.; Zhukov, S. V.; Zinatulina, D.; Zuber, K.; Zuzel, G.

2017-09-01

The observation of neutrinoless double beta decay would allow to shed light onto the particle nature of neutrinos. Gerda is aiming to perform a background-free search for this process using high purity germanium detectors enriched in 76Ge operated in liquid argon. This goal relies on the application of active background suppression techniques. A low background light instrumentation has been installed for Phase II to detect events with coincident energy deposition in the nearby liquid argon. The intended background index of ˜10-3 cts/(keV·ky·yr) has been confirmed.

Potential sea salt aerosol sources from frost flowers in the pan-Arctic region

Energy Technology Data Exchange (ETDEWEB)

Xu, Li [Scripps Institution of Oceanography, University of California, San Diego, La Jolla California USA; Now at Department of Earth System Science, University of California, Irvine California USA; Russell, Lynn M. [Scripps Institution of Oceanography, University of California, San Diego, La Jolla California USA; Burrows, Susannah M. [Atmospheric Science and Global Change Division, Pacific Northwest National Laboratory, Richland Washington USA

2016-09-23

In order to better represent observed wintertime aerosol concentrations at Barrow, Alaska, we implemented an observationally-based parameterization for estimating sea salt production from frost flowers in the Community Earth System Model (CESM). In this work, we evaluate the potential influence of this sea salt source on the pan-Arctic (60ºN-90ºN) climate. Results show that frost flower salt emissions substantially increase the modeled surface sea salt aerosol concentration in the winter months when new sea ice and frost flowers are present. The parameterization reproduces both the magnitude and seasonal variation of the observed submicron sea salt aerosol concentration at surface in Barrow during winter much better than the standard CESM simulation without a frost-flower salt particle source. Adding these frost flower salt particle emissions increases aerosol optical depth by 10% and results in a small cooling at surface. The increase in salt particle mass concentrations of a factor of 8 provides nearly two times the cloud condensation nuclei concentration, as well as 10% increases in cloud droplet number and 40% increases in liquid water content near coastal regions adjacent to continents. These cloud changes reduce longwave cloud forcing by 3% and cause a small surface warming, increasing the downward longwave flux at the surface by 2 W m-2 in the pan-Arctic under the present-day climate.

New argon-argon (40Ar/39Ar) radiometric age dates from selected subsurface basalt flows at the Idaho National Laboratory, Idaho

Science.gov (United States)

Hodges, Mary K. V.; Turrin, Brent D.; Champion, Duane E.; Swisher, Carl C.

2015-01-01

In 2011, the U.S. Geological Survey, in cooperation with the U.S. Department of Energy, collected samples for 12 new argon-argon radiometric ages from eastern Snake River Plain olivine tholeiite basalt flows in the subsurface at the Idaho National Laboratory. The core samples were collected from flows that had previously published paleomagnetic data. Samples were sent to Rutgers University for argon-argon radiometric dating analyses.

Germination and seedling frost tolerance differ between the native and invasive range in common ragweed.

Science.gov (United States)

Leiblein-Wild, Marion Carmen; Kaviani, Rana; Tackenberg, Oliver

2014-03-01

Germination characteristics and frost tolerance of seedlings are crucial parameters for establishment and invasion success of plants. The characterization of differences between populations in native and invasive ranges may improve our understanding of range expansion and adaptation. Here, we investigated germination characteristics of Ambrosia artemisiifolia L., a successful invader in Europe, under a temperature gradient between 5 and 25 °C. Besides rate and speed of germination we determined optimal, minimal and maximal temperature for germination of ten North American and 17 European populations that were sampled along major latitudinal and longitudinal gradients. We furthermore investigated the frost tolerance of seedlings. Germination rate was highest at 15 °C and germination speed was highest at 25 °C. Germination rate, germination speed, frost tolerance of seedlings, and the temperature niche width for germination were significantly higher and broader, respectively, for European populations. This was partly due to a higher seed mass of these populations. Germination traits lacked evidence for adaptation to climatic variables at the point of origin for both provenances. Instead, in the native range, seedling frost tolerance was positively correlated with the risk of frosts which supports the assumption of local adaptation. The increased frost tolerance of European populations may allow germination earlier in the year which may subsequently lead to higher biomass allocation--due to a longer growing period--and result in higher pollen and seed production. The increase in germination rates, germination speed and seedling frost tolerance might result in a higher fitness of the European populations which may facilitate further successful invasion and enhance the existing public health problems associated with this species.

Modeling monthly meteorological and agronomic frost days, based on minimum air temperature, in Center-Southern Brazil

Science.gov (United States)

Alvares, Clayton Alcarde; Sentelhas, Paulo César; Stape, José Luiz

2017-09-01

Although Brazil is predominantly a tropical country, frosts are observed with relative high frequency in the Center-Southern states of the country, affecting mainly agriculture, forestry, and human activities. Therefore, information about the frost climatology is of high importance for planning of these activities. Based on that, the aims of the present study were to develop monthly meteorological (F MET) and agronomic (F AGR) frost day models, based on minimum shelter air temperature (T MN), in order to characterize the temporal and spatial frost days variability in Center-Southern Brazil. Daily minimum air temperature data from 244 weather stations distributed across the study area were used, being 195 for developing the models and 49 for validating them. Multivariate regression models were obtained to estimate the monthly T MN, once the frost day models were based on this variable. All T MN regression models were statistically significant (p Brazilian region are the first zoning of these variables for the country.

Influence of low temperature and frost duration on Phytophthora alni subsp. alni viability

Energy Technology Data Exchange (ETDEWEB)

Cerny, K.; Filipova, N.; Strnadova, V.

2012-11-01

Limits on the survival of P. alni subsp. alni (PAA) due to low temperature can be expected based on previously published laboratory and field studies. This study presents a laboratory experiment to test the influence of low temperature and frost duration on PAA viability. Ten PAA isolates were incubated at different temperatures (-0.1, -2.5, -5.0, -7.5, and -10.0 degree centigrade) and frost durations (0 - 7, 14, 21, and 28 days). A regression analysis confirmed the significant influence of both factors (low temperature and frost duration, and their interaction) on the survival of the pathogen under laboratory conditions. The survival and failure time analysis showed that the survival of the pathogen differs significantly after mild frost (all the isolates tested survived temperatures between -0.1 and -5.0 degree centigrade during the entire testing period) and heavy frost (the pathogen died after 21 days of incubation at -7.5 degree centigrade and after 2 days at -10.0 degree centigrade). Moreover, the viability of the pathogen decreased significantly if the temperature of -5.0 degree centigrade was maintained for at least 1 week and the temperature of -7.5 degree centigrade persisted in laboratory conditions for at least 4 days. The results of the study proved the pathogen to be very sensitive to heavy frost. The low-temperature limits for PAA occur regularly in Central Europe in January. It is probable that these temperatures can reduce PAA populations in diseased black alder stems. The climate change characterised by increases in the lowest minimum winter temperatures in Central Europe (as hypothesised by IPCC) may pose a significant risk for affected alder population in the area. (Author) 21 refs.

Cryopumping of deuterium hydrogen and helium mixtures on smooth 4.2 K surfaces

International Nuclear Information System (INIS)

Chou, T.S.; Halama, H.J.

1977-01-01

The large quantities of deuterium and hydrogen to be pumped in a fusion reactor and its subsystems favor cryopumping over other pumping methods. Cryogen consumption and the operating pressure will not only depend on the gas to be pumped, but also on the amount of helium gas present in the system. In fact, residual helium pressure between pulses will determine the power dissipation of the pump, and hence, influence the choice of cryocondensation or cryosorption. In this paper we will present the results of our studies on (1) cryotrapping of helium in thick D 2 and H 2 films and hydrogen in D 2 films at 4.2 K; (2) diffusion of He and H 2 from D 2 films; (3) steady-state liquid helium consumption; (4) liquid helium consumption as a function of D 2 and H 2 fluxes being pumped; (5) liquid helium consumption as a function of He partial pressure in the system. Finally, these measurements will suggest maximum permissible He to D 2 and He to H 2 ratios in a cryocondensation pump

Argon green-Nd: YAG dual laser posterior hyaloidotomy: An innovative approach toward treatment of premacular hemorrhage

Directory of Open Access Journals (Sweden)

Ashish Sharma

2013-01-01

Full Text Available Background: Neodymium: YAG (Nd: YAG laser and argon laser has been used to treat premacular hemorrhage either alone or rarely in combination. Materials and Methods: We describe a new technique of treating premacular hemorrhage by performing hyaloidotomy using a combination of argon green-Nd: YAG laser. We utilized subthreshold energy levels of Nd: YAG laser of 2.0 mJ as compared to the normal recommendation of 3.6-50 mJ. Results and Conclusions: This technique is easy, effective, and safe to manage premacular hemorrhage. The principle behind this combined laser treatment was to make the internal limiting membrane (ILM taut by initial exposure to argon green laser, which allowed us to employ the subthreshold energy levels of Nd: YAG laser. We would like to assess the role of this combined treatment modality in comparison to other modalities, including solitary laser therapy in the management of premacular hemorrhage by performing a prospective, randomized long-term study.

Status of the ATLAS Liquid Argon Calorimeter and its performance after one year of LHC operation

CERN Document Server

"Hoffman, J A; The ATLAS collaboration

2011-01-01

The ATLAS experiment is designed to study the proton-proton collisions produced at the LHC with a centre-of-mass energy of 14 TeV. Liquid argon (LAr) sampling calorimeters are used in ATLAS for all electromagnetic calorimetry covering the pseudorapidity region η<3.2, as well as for hadronic calorimetry from η=1.4 to η=4.8. The calorimeter system consists of an electromagnetic barrel calorimeter and two endcaps with electromagnetic (EMEC), hadronic (HEC) and forward (FCAL) calorimeters. The lead-liquid argon sampling technique with an accordion geometry was chosen for the barrel electromagnetic calorimeter (EMB) and adapted to the endcap (EMEC). This geometry allows a uniform acceptance over the whole azimuthal range without any gap. The hadronic endcap calorimeter (HEC) uses a copper-liquid argon sampling technique with plate geometry and is subdivided into two wheels in depth per end-cap. Finally, the forward calorimeter (FCAL) is composed of three modules featuring cylindrical electrodes with thin...

Dunes with Frost

Science.gov (United States)

2004-01-01

31 May 2004 Springtime for the martian northern hemisphere brings defrosting spots and patterns to the north polar dune fields. This Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC) image shows an example located near 76.7oN, 250.4oW. In summer, these dunes would be darker than their surroundings. However, while they are still covered by frost, they are not any darker than the substrate across which the sand is slowly traveling. Dune movement in this case is dominated by winds that blow from the southwest (lower left) toward the northeast (upper right). The picure covers an area about 3 km (1.9 mi) across and is illuminated by sunlight from the lower left.

The distribution of water frost on Charon

Science.gov (United States)

Buie, Marc W.; Shriver, Scott K.

1994-01-01

We present high-spatial-resolution imaging observations of the Pluto-Charon system taken with ProtoCAM on the Infrared Telescope Facility (IRTF). Our dataset consists of measurements from eight nights at widely separated rotational longitudes and covering five wavelengths -- standard J, H, and K, plus two special narrow band filters at 1.5 and 1.75 microns. The relative flux contributions of Pluto and Charon were extracted, when possible, by fitting a two-source Gaussian image model to the observed images. At K, we find the Charon-Pluto magnitude difference to be on average 1.8 mag, somewhat less than the value of 2.2 mag found by Bosh et al. (1992). The average differential magnitude at 1.5 and 1.75 microns is 2.0 and 1.6, respectively. The larger magnitude difference at 1.5 microns is due to a water-frost absorption band on the surface of Charon. Our observations are consistent with a surface of Charon dominated by water frost at all longitudes.

FROST: an ASIC for digital mammography with synchrotron radiation

International Nuclear Information System (INIS)

Bergamaschi, A.; Prest, M.; Vallazza, E.; Arfelli, F.; Dreossi, D.; Longo, R.; Olivo, A.; Pani, S.; Castelli, E.

2003-01-01

The FRONTier RADiography (FRONTRAD) collaboration is developing a digital system for mammography at the Elettra Synchrotron Light Source in Trieste. The system is based on a silicon microstrip detector array. The ASIC FROST (FRONTRAD Read Out sySTem) was developed as a collaboration between INFN Trieste and Aurelia Microelettronica and is designed to operate in single photon counting mode. FROST provides low-noise and high-gain performances and is able to work at incident photon rates higher than 100 kHz with almost 100% efficiency. The ASIC has been tested and the first images of mammographic test objects will be shown. The acquisition time per breast image should be of about 10 s

The Physics of Frost Heave and Ice-Lens Growth

KAUST Repository

Peppin, Stephen S. L.

2013-01-01

The principle cause of frost heave is the formation of segregated ice-ice lenses-in freezing soil columns. Despite much experimental and theoretical work, there remain many questions about the fundamental process by which this occurs. Frost-heave models fall into two main classes: capillary and frozen-fringe models. Which model is appropriate depends on whether there is a frozen fringe; these are difficult to observe but some experimental evidence does exist. Recent advances have revitalized the capillary model, such as the engulfment model and the concept of geometrical supercooling. Key experimental and theoretical challenges remain to be resolved. © Soil Science Society of America 5585 Guilford Rd., Madison, WI 53711 USA. All rights reserved.

Statistical-Synoptic Analysis of the Atmosphere Thickness Pattern of Iran’s Pervasive Frosts

Directory of Open Access Journals (Sweden)

Iman Rousta

2016-08-01

Full Text Available The present study aimed at analyzing the synoptic pattern of atmospheric thickness of winter pervasive frosts in Iran. To this end, the data related to the daily minimum temperature of a 50-year period (1961–2010 were gathered from 451 synoptic and climatology stations. Then, the instances in which the temperature was below 0 °C for at least two consecutive days and this phenomenon covered at least 50% of the entirety of Iran were selected. Subsequently, the atmosphere thickness pattern was extracted for these days, with the representative day being identified and analyzed through cluster analysis. The results showed that the Siberian high pressure plays a significant role in the occurrence of pervasive frosts in Iran. In some other cases, the northeast–southwest direction of this pattern leads to its combination with the East Europe high pressure, causing widespread frosts in Iran. Furthermore, the interaction between counter clockwise currents in this system and the clockwise currents in the Azores high pressure tongue directs cold weather from northern parts of Europe toward Iran. The formation of blocking systems leads to the stagnation of cold weather over Iran, a phenomenon that results in significant reduction of temperature and severe frosts in these areas. In addition, the omega pattern (the fifth pattern and Deep Eastern European trough and polar low pressure pattern (the fourth pattern were the most dominant and severe frost patterns in Iran respectively.

Morning Frost in Trench Dug by Phoenix, Sol 113

Science.gov (United States)

2008-01-01

This image from the Surface Stereo Imager on NASA's Phoenix Mars Lander shows morning frost inside the 'Snow White' trench dug by the lander, in addition to subsurface ice exposed by use of a rasp on the floor of the trench. The camera took this image at about 9 a.m. local solar time during the 113th Martian day of the mission (Sept. 18, 2008). Bright material near and below the four-by-four set of rasp holes in the upper half of the image is water-ice exposed by rasping and scraping in the trench earlier the same morning. Other bright material especially around the edges of the trench, is frost. Earlier in the mission, when the sun stayed above the horizon all night, morning frost was not evident in the trench. This image is presented in approximately true color. The trench is 4 to 5 centimeters (about 2 inches) deep, about 23 centimeters (9 inches) wide. Phoenix landed on a Martian arctic plain on May 25, 2008. The mission is led by the University of Arizona, Tucson, on behalf of NASA. Project management of the mission is led by NASA's Jet Propulsion Laboratory, Pasadena, Calif. Spacecraft development was by Lockheed Martin Space Systems, Denver.

Polydiagnostic calibration performed on a low pressure surface wave sustained argon plasma

NARCIS (Netherlands)

Vries, de N.; Palomares, J.M.; Iordanova, E.I.; Veldhuizen, van E.M.; Mullen, van der J.J.A.M.

2008-01-01

The electron density and electron temperature of a low pressure surface wave sustained argon plasma have been determined using passive and active (laser) spectroscopic methods simultaneously. In this way the validity of the various techniques is established while the plasma properties are determined

Identification and Verification of QTL Associated with Frost Tolerance Using Linkage Mapping and GWAS in Winter Faba Bean

Science.gov (United States)

Sallam, Ahmed; Arbaoui, Mustapha; El-Esawi, Mohamed; Abshire, Nathan; Martsch, Regina

2016-01-01

Frost stress is one of the abiotic stresses that causes a significant reduction in winter faba bean yield in Europe. The main objective of this work is to genetically improve frost tolerance in winter faba bean by identifying and validating QTL associated with frost tolerance to be used in marker-assisted selection (MAS). Two different genetic backgrounds were used: a biparental population (BPP) consisting of 101 inbred lines, and 189 genotypes from single seed descent (SSD) from the Gottingen Winter bean Population (GWBP). All experiments were conducted in a frost growth chamber under controlled conditions. Both populations were genotyped using the same set of 189 SNP markers. Visual scoring for frost stress symptoms was used to define frost tolerance in both populations. In addition, leaf fatty acid composition (FAC) and proline content were analyzed in BPP as physiological traits. QTL mapping (for BPP) and genome wide association studies (for GWBP) were performed to detect QTL associated with frost tolerance. High genetic variation between genotypes, and repeatability estimates, were found for all traits. QTL mapping and GWAS identified new putative QTL associated with promising frost tolerance and related traits. A set of 54 SNP markers common in both genetic backgrounds showed a high genetic diversity with polymorphic information content (PIC) ranging from 0.31 to 0.37 and gene diversity ranging from 0.39 to 0.50. This indicates that these markers may be polymorphic for many faba bean populations. Five SNP markers showed a significant marker-trait association with frost tolerance and related traits in both populations. Moreover, synteny analysis between Medicago truncatula (a model legume) and faba bean genomes was performed to identify candidate genes for these markers. Collinearity was evaluated between the faba bean genetic map constructed in this study and the faba bean consensus map, resulting in identifying possible genomic regions in faba bean which may

Identification and Verification of QTL Associated with Frost Tolerance Using Linkage Mapping and GWAS in Winter Faba Bean.

Science.gov (United States)

Sallam, Ahmed; Arbaoui, Mustapha; El-Esawi, Mohamed; Abshire, Nathan; Martsch, Regina

2016-01-01

Frost stress is one of the abiotic stresses that causes a significant reduction in winter faba bean yield in Europe. The main objective of this work is to genetically improve frost tolerance in winter faba bean by identifying and validating QTL associated with frost tolerance to be used in marker-assisted selection (MAS). Two different genetic backgrounds were used: a biparental population (BPP) consisting of 101 inbred lines, and 189 genotypes from single seed descent (SSD) from the Gottingen Winter bean Population (GWBP). All experiments were conducted in a frost growth chamber under controlled conditions. Both populations were genotyped using the same set of 189 SNP markers. Visual scoring for frost stress symptoms was used to define frost tolerance in both populations. In addition, leaf fatty acid composition (FAC) and proline content were analyzed in BPP as physiological traits. QTL mapping (for BPP) and genome wide association studies (for GWBP) were performed to detect QTL associated with frost tolerance. High genetic variation between genotypes, and repeatability estimates, were found for all traits. QTL mapping and GWAS identified new putative QTL associated with promising frost tolerance and related traits. A set of 54 SNP markers common in both genetic backgrounds showed a high genetic diversity with polymorphic information content (PIC) ranging from 0.31 to 0.37 and gene diversity ranging from 0.39 to 0.50. This indicates that these markers may be polymorphic for many faba bean populations. Five SNP markers showed a significant marker-trait association with frost tolerance and related traits in both populations. Moreover, synteny analysis between Medicago truncatula (a model legume) and faba bean genomes was performed to identify candidate genes for these markers. Collinearity was evaluated between the faba bean genetic map constructed in this study and the faba bean consensus map, resulting in identifying possible genomic regions in faba bean which may

Plant safety margin against frost damages has declined in Switzerland over the last four decades

Science.gov (United States)

Vitasse, Yann; Schneider, Léonard; Klein, Geoffrey; Rixen, Christian; Rebetez, Martine

2017-04-01

Winters and early springs have become warmer over the last decades which has in turn promoted earlier plant development in temperate regions. While temperatures will on average continue to increase in the coming decades due to the rise of greenhouse gases concentration in the atmosphere, there is no consensus about how the occurrence of late spring frosts will change. If the frequency and the severity of late spring frosts remain unchanged in the future or advance less than vegetation onset, vulnerable plant organs (young leaves, flowers or dehardened buds) may be more exposed to frost damage. Here we analyzed long-term series of temperature data during the period 1975-2016 at 50 locations in Switzerland. We used different thresholds of growing degree days (GDD) as a proxy for spring phenology of fruit trees based on long-term series of phenological observations. Finally, we tested whether the time lag between the date when the GDD is reached and the latest occurrence of frost has changed over the study period. Overall we found that the safety margin against potential frost damage to plants has slightly decreased during the study period, irrespective of elevation (from 203 to 2283 m). Our results suggest that the cost for preventing frost damages on fruit trees could increase in the coming decades and the introduction of new varieties of fruit trees adapted to warmer climate should be carefully considered as they generally exhibit earlier spring phenology.

Ice Segregation and Frost Heaving.

Science.gov (United States)

1984-01-01

to a buried chilled gas pipeline by continual frost ’. ’- heave during the service life or to a buried liquefied gas tank is a more _ recent concern...M). Lule en: Uiversity of Lulea. Pehner, E., 1982. Aspects of ice lens fornmation. P ing of the Third International Syvosium on Ground Freezi, Hanover...Soils. Lalea, Sweden: Uiversity ofLulea. . Berg, R. L., G. Guymon and J. Ingersoll, 1979. Conference on soil-water . problems in cold regions. Cold

Development and Sensitivity Analysis of a Frost Risk model based primarily on freely distributed Earth Observation data

Science.gov (United States)

Louka, Panagiota; Petropoulos, George; Papanikolaou, Ioannis

2015-04-01

The ability to map the spatiotemporal distribution of extreme climatic conditions, such as frost, is a significant tool in successful agricultural management and decision making. Nowadays, with the development of Earth Observation (EO) technology, it is possible to obtain accurately, timely and in a cost-effective way information on the spatiotemporal distribution of frost conditions, particularly over large and otherwise inaccessible areas. The present study aimed at developing and evaluating a frost risk prediction model, exploiting primarily EO data from MODIS and ASTER sensors and ancillary ground observation data. For the evaluation of our model, a region in north-western Greece was selected as test site and a detailed sensitivity analysis was implemented. The agreement between the model predictions and the observed (remotely sensed) frost frequency obtained by MODIS sensor was evaluated thoroughly. Also, detailed comparisons of the model predictions were performed against reference frost ground observations acquired from the Greek Agricultural Insurance Organization (ELGA) over a period of 10-years (2000-2010). Overall, results evidenced the ability of the model to produce reasonably well the frost conditions, following largely explainable patterns in respect to the study site and local weather conditions characteristics. Implementation of our proposed frost risk model is based primarily on satellite imagery analysis provided nowadays globally at no cost. It is also straightforward and computationally inexpensive, requiring much less effort in comparison for example to field surveying. Finally, the method is adjustable to be potentially integrated with other high resolution data available from both commercial and non-commercial vendors. Keywords: Sensitivity analysis, frost risk mapping, GIS, remote sensing, MODIS, Greece

Supersonic expansion of argon into vacuum

Energy Technology Data Exchange (ETDEWEB)

Habets, A H.M.

1977-01-21

A theoretical description of a free supersonic expansion process is given. Three distinct regions in the expansion are discussed, namely the continuum region, the gradual transition to the collisionless regime, and the free-molecular-flow stage. Important topics are the peaking-factor formalism, the thermal-conduction model, and the virtual-source formalism. The formation of the molecular beam from the expansion and condensation phenomena occurring in the expanding gas are discussed. The molecular beam machine used in the measurements is described and special attention is given to the cryopumps used in the supersonic sources as well as to the time-of-flight analysis of the molecular beam velocity distributions. Finally, the processing of experimental data is discussed, particularly the least-squares determination of best-fit representations of the measurements.

Supersonic expansion of argon into vacuum

International Nuclear Information System (INIS)

Habets, A.H.M.

1977-01-01

A theoretical description of a free supersonic expansion process is given. Three distinct regions in the expansion are discussed, namely the continuum region, the gradual transition to the collisionless regime, and the free-molecular-flow stage. Important topics are the peaking-factor formalism, the thermal-conduction model, and the virtual-source formalism. The formation of the molecular beam from the expansion and condensation phenomena occurring in the expanding gas are discussed. The molecular beam machine used in the measurements is described and special attention is given to the cryopumps used in the supersonic sources as well as to the time-of-flight analysis of the molecular beam velocity distributions. Finally, the processing of experimental data is discussed, particularly the least-squares determination of best-fit representations of the measurements

Delayed condensation and frost formation on superhydrophobic carbon soot coatings by controlling the presence of hydrophilic active sites

Science.gov (United States)

Esmeryan, Karekin D.; Castano, Carlos E.; Mohammadi, Reza; Lazarov, Yuliyan; Radeva, Ekaterina I.

2018-02-01

Condensation frosting is an undesired natural phenomenon that could be impeded efficiently using appropriate wettability and morphologically patterned surfaces. The icephobic properties of carbon soot and the fabrication scalability of its synthesis method are a good foundation for anti-frosting applications; however, the fundamentals of frost growth and spreading on sooted surfaces have not been examined yet. In this study, we investigate the anti-frosting performance of three groups of superhydrophobic soot coatings by means of 16 MHz quartz crystal microbalances (QCMs). The analysis of the real-time sensor signal of each soot coated QCM pattern shows that frost formation and its propagation velocity depend on the quantity of oxygen functionalities and structural defects in the material. In turn, the reduction of both parameters shifts the onset of frost growth to temperatures below  -20 °C, whereas the interdroplet ice bridging is slowed by a factor of four. Moreover, high-resolution scanning electron micrographs of the samples imply delamination upon defrosting of the soot with spherical-like morphology via polar interactions driven mechanism. These results reveal an opportunity for control of frost incipiency on sooted surfaces by adjusting the synthesis conditions and depositing soot coatings with as low as possible content of hydrophilic active sites.

A G/NARRLI Effort. Measuring the Ionization Yield of Low-Energy Nuclear Recoils in Liquid Argon

Energy Technology Data Exchange (ETDEWEB)

Joshi, Tenzing Henry Yatish [Univ. of California, Berkeley, CA (United States)

2014-01-01

Liquid argon has long been used for particle detection due to its attractive drift properties, ample abundance, and reasonable density. The response of liquid argon to lowenergy O(10² -10⁴4 eV) interactions is, however, largely unexplored. Weakly interacting massive particles such as neutrinos and hypothetical dark-matter particles (WIMPs) are predicted to coherently scatter on atomic nuclei, leaving only an isolated low-energy nuclear recoil as evidence. The response of liquid argon to low-energy nuclear recoils must be studied to determine the sensitivity of liquid argon based detectors to these unobserved interactions. Detectors sensitive to coherent neutrino-nucleus scattering may be used to monitor nuclear reactors from a distance, to detect neutrinos from supernova, and to test the predicted behavior of neutrinos. Additionally, direct detection of hypothetical weakly interacting dark matter would be a large step toward understanding the substance that accounts for nearly 27% of the universe. In this dissertation I discuss a small dual-phase (liquid-gas) argon proportional scintillation counter built to study the low-energy regime and several novel calibration and characterization techniques developed to study the response of liquid argon to low-energy O(10² -10⁴ eV) interactions.

Phenomenological modeling of argon Z-pinch implosions

International Nuclear Information System (INIS)

Whitney, K.G.; Thornhill, J.W.; Deeney, C.; LePell, P.D.; Coulter, M.C.

1992-01-01

The authors investigate some of the effects of plasma turbulence on the K-shell emission dynamics of argon gas puff Z-pinch implosions. The increases that turbulence produces in the plasma viscosity, heat conductivity, and electrical resistivity are modeled phenomenologically using multipliers for these quantities in the MHD calculations. The choice of multipliers was made by benchmarking a 1-D MHD simulation of a Physics International Inc. argon gas puff experiment against the inferred densities and temperatures achieved in the experiment. These multipliers were then used to study the parametric dependence of the K-shell emission on the energy input to the argon plasma for a fixed mass loading. Comparisons between turbulent and non-turbulent argon implosions are made

Coatings to prevent frost

DEFF Research Database (Denmark)

Lusada, Ricardo; Holberg, Stefan; Bennedsen, Jeanette Marianne Dalgaard

2016-01-01

The ability of hydrophobic, organic–inorganic hybrid coatings to decelerate frost propagation was investigated. Compared to a bare aluminum surface, the coatings do not significantly reduce the freezing probability of supercooled water drops. On both surfaces, the probability for ice nucleation...... at temperatures just below 0°C, for example at −4°C, is low. Freezing of a single drop on aluminum leads, however, to instant freezing of the complete surface. On hydrophobic coatings, such a freezing drop is isolated; the frozen area grows slowly. At −4°C surface temperature in a +12°C/90% relative humidity...

Metal stress consequences on frost hardiness of plants at northern high latitudes: a review and hypothesis.

Science.gov (United States)

Taulavuori, Kari; Prasad, M N V; Taulavuori, Erja; Laine, Kari

2005-05-01

This paper reviews the potential of trace/heavy metal-induced stress to reduce plant frost hardiness at northern high latitudes. The scientific questions are first outlined prior to a brief summary of heavy metal tolerance. The concepts of plant capacity and survival adaptation were used to formulate a hypothesis, according to which heavy metal stress may reduce plant frost hardiness for the following reasons: (1) Heavy metals change membrane properties through impaired resource acquisition and subsequent diminution of the cryoprotectant pool. (2) Heavy metals change membrane properties directly through oxidative stress, i.e. an increase of active oxygen species. (3) The involved co-stress may further increase oxidative stress. (4) The risk of frost injury increases due to membrane alterations. An opposite perspective was also discussed: could metal stress result in enhanced plant frost hardiness? This phenomenon could be based on the metabolism (i.e. glutathione, polyamines, proline, heat shock proteins) underlying a possible general adaptation syndrome of stress (GAS). As a result of the review it was suggested that metal-induced stress seems to reduce rather than increase plant frost hardiness.

Control of dew and frost formation on leaf by radiative cooling

International Nuclear Information System (INIS)

Matsui, T.; Eguchi, H.; Mori, K.

1981-01-01

A radiative cooling system was developed to control dew and frost formations and to examine the effect of the radiative cooling on the leaf temperature. The growth chamber was provided with a box which was constructed by using heat insulating materials to minimize the disturbances and to regulate the air current. A cooling coil (cooling surface of 300 cm was equipped at the bottom of the box and manipulated by a refrigerator of 1, 430 kcal hour -1 , and a concave mirror was attached to the ceiling of the box to facilitate the reflection of the radiation from the leaf to the cooling coil. The moisture in air was supplied by flowing the controlled air (0.2 m min -1 ) into the box. The distribution of dew point temperatures was almost uniform horizontally even under vertically slight conversion (downward velocity of 1.3 cm sec -1 ) of the air. The leaf temperature became about 1.0°C lower than the ambient air temperature under the radiative cooling. The dew and the frost were clearly observed on the leaf after the time when the leaf temperature had become lower than the dew point temperature. The dew increased in size in course of time, and the frost varied in shape and in size with the temperatures. Thus, artificial formations of the dew and the frost were made possible by the radiative cooling system developed in this experiment

Frosts during the growing season. Frequency of occurrence and effects on current energy forestry. Sommarfroster. Foerekomster och effekter paa befintliga energiskogsodlingar

Energy Technology Data Exchange (ETDEWEB)

Christersson, L; Fircks, H von; Perttu, K

1984-01-01

Frost during the summer is very common in Sweden. Two kinds of summer frosts exists; one is called advection frost which is caused by cold air coming down over the country from the north and the other is an inversion frost caused by long-wave radiation from the ground taking place during calm clear nights. In this way the air closest to the ground is cooled. Eleven experimental areas are described as regards prehistory, vegetation, frequency of summer frosts, and energy forestry tests in progress. The amount of frost injuries is reported. Differences in frost hardiness of fast growing Salix clones in the growing state have been demonstrated. The results support the idea that the formation of ice crystals inside the growing tissues always take place around -2 degree C and that this ice crystal formation damages the growing part of the shoot of all tested clones. A fast growing shoot of Salix species has a longer elongation zone and this explains why a fast-growing shoot is more severly damaged than a slowly growing one at the same frost temperature. If the different clones are in a growing state there are only small differences in the amount of frost damage. On the other hand, there are great differences between the clones in the capacity of the surviving lateral buds to sprout. This capacity is foremost seen in clones of the species Salix dasyclados. Two year older shoots of different Salix species have never been damaged by summer frost because summer frosts do not reach the elongating zone of these shoots. In conclusions measures are listed on how to prevent or decrease the injuries caused by summer frosts. With 21 refs.

Electrical and spectroscopic diagnostic of an atmospheric double arc argon plasma jet

International Nuclear Information System (INIS)

Tu, X; Cheron, B G; Yan, J H; Cen, K F

2007-01-01

An atmospheric argon plasma jet generated by an original dc double anode plasma torch has been investigated through its electrical and spectroscopic diagnostics. The arc instabilities and dynamic behavior of the argon plasma are analyzed using classical tools such as the statistical method, fast Fourier transform (FFT) and correlation function. The takeover mode is identified as the fluctuation characteristic of the double arc argon plasma jet in our experiment. The FFT and correlation analysis of electrical signals exhibit the only characteristic frequency of 150 Hz, which originates from the torch power and is independent of any change in the operating parameters. No high frequency fluctuations (1-15 kHz) are observed. This indicates that the nature of fluctuations in an argon plasma jet is induced mainly by the undulation of the tri-phase rectified power supply. It is found that each arc root attachment is diffused rather than located at a fixed position on the anode wall. Moreover, the emission spectroscopic technique is performed to determine the electron temperature and number density of the plasma jet inside and outside the arc chamber. Along the torch axis, the measured electron temperature and number density of the double arc argon plasma drop from 12 300 K and 7.6 x 10 22 m -3 at the divergent part of the first anode nozzle, to 10 500 K and 3.1 x 10 22 m -3 at the torch exit. In addition, the validity criteria of the local thermodynamic equilibrium (LTE) state in the plasma arc are examined. The results show that the measured electron densities are in good agreement with those calculated from the LTE model, which indicates that the double arc argon plasma at atmospheric pressure is close to the LTE state under our experimental conditions

Post-head-emergence frost in wheat and barley: defining the problem, assessing the damage, and identifying resistance.

Science.gov (United States)

Frederiks, T M; Christopher, J T; Sutherland, M W; Borrell, A K

2015-06-01

Radiant frost is a significant production constraint to wheat (Triticum aestivum) and barley (Hordeum vulgare), particularly in regions where spring-habit cereals are grown through winter, maturing in spring. However, damage to winter-habit cereals in reproductive stages is also reported. Crops are particularly susceptible to frost once awns or spikes emerge from the protection of the flag leaf sheath. Post-head-emergence frost (PHEF) is a problem distinct from other cold-mediated production constraints. To date, useful increased PHEF resistance in cereals has not been identified. Given the renewed interest in reproductive frost damage in cereals, it is timely to review the problem. Here we update the extent and impacts of PHEF and document current management options to combat this challenge. We clarify terminology useful for discussing PHEF in relation to chilling and other freezing stresses. We discuss problems characterizing radiant frost, the environmental conditions leading to PHEF damage, and the effects of frost at different growth stages. PHEF resistant cultivars would be highly desirable, to both reduce the incidence of direct frost damage and to allow the timing of crop maturity to be managed to maximize yield potential. A framework of potential adaptation mechanisms is outlined. Clarification of these critical issues will sharpen research focus, improving opportunities to identify genetic sources for improved PHEF resistance. © The Author 2015. Published by Oxford University Press on behalf of the Society for Experimental Biology. All rights reserved. For permissions, please email: journals.permissions@oup.com.

Prospects for photosensitive dopants in liquid argon

International Nuclear Information System (INIS)

Anderson, D.F.

1990-12-01

Evidence is presented that the addition of a few ppM of a photosensitive dopant to a U/liquid argon or Pb/liquid argon calorimeter will make a substantial reduction in the e/π ratio. Previous results indicating high voltage problems and no change in the e/π ratio in tests of photosensitive dopants with the Fermilab D0 experiment's U/liquid argon tests calorimeter are also explained. 13 refs., 3 figs

Ground level air convection produces frost damage patterns in turfgrass.

Science.gov (United States)

Ackerson, Bruce J; Beier, Richard A; Martin, Dennis L

2015-11-01

Frost injury patterns are commonly observed on the warm-season turfgrass species bermudagrass (Cynodon species Rich.), zoysiagrass (Zoysia species Willd.), and buffalograss [Bouteloua dactyloides (Nutt.) J.T. Columbus] in cool-temperate and subtropical zones. Qualitative observations of these injury patterns are presented and discussed. A model for the formation of such patterns based on thermal instability and convection of air is presented. The characteristic length scale of the observed frost pattern injury requires a temperature profile that decreases with height from the soil to the turfgrass canopy surface followed by an increase in temperature with height above the turfgrass canopy. This is justified by extending the earth temperature theory to include a turf layer with atmosphere above it. Then the theory for a thermally unstable layer beneath a stable region by Ogura and Kondo is adapted to a turf layer to include different parameter values for pure air, as well as for turf, which is treated as a porous medium. The earlier porous medium model of Thompson and Daniels proposed to explain frost injury patterns is modified to give reasonable agreement with observed patterns.

Ground level air convection produces frost damage patterns in turfgrass

Science.gov (United States)

Ackerson, Bruce J.; Beier, Richard A.; Martin, Dennis L.

2015-11-01

Frost injury patterns are commonly observed on the warm-season turfgrass species bermudagrass ( Cynodon species Rich.), zoysiagrass ( Zoysia species Willd.), and buffalograss [ Bouteloua dactyloides (Nutt.) J.T. Columbus] in cool-temperate and subtropical zones. Qualitative observations of these injury patterns are presented and discussed. A model for the formation of such patterns based on thermal instability and convection of air is presented. The characteristic length scale of the observed frost pattern injury requires a temperature profile that decreases with height from the soil to the turfgrass canopy surface followed by an increase in temperature with height above the turfgrass canopy. This is justified by extending the earth temperature theory to include a turf layer with atmosphere above it. Then the theory for a thermally unstable layer beneath a stable region by Ogura and Kondo is adapted to a turf layer to include different parameter values for pure air, as well as for turf, which is treated as a porous medium. The earlier porous medium model of Thompson and Daniels proposed to explain frost injury patterns is modified to give reasonable agreement with observed patterns.

Effect of Emergency Argon on FCF Operational Incidents

International Nuclear Information System (INIS)

Solbrig, Charles

2011-01-01

The following report presents analyses of operational incidents which are considered in the safety analysis of the FCF argon cell and the effect that the operability of the emergency argon system has on the course of these incidents. The purpose of this study is to determine if the emergency argon system makes a significant difference in ameliorating the course of these incidents. Six incidents were considered. The following three incidents were analyzed. These are: 1. Cooling failing on 2. Vacuum Pump Failing on 3. Argon Supplies Failing on. In the remaining three incidents, the emergency argon supply would have no effect on the course of these transients since it would not come on during these incidents. The transients are 1. Loss of Cooling 2. Loss of power (Differs from above by startup delay till the Diesel Generators come on.) 3. Cell rupture due to an earthquake or other cause. The analyses of the first three incidents are reported on in the next three sections. This report is issued realizing the control parameters used may not be optimum, and additional modeling must be done to model the inertia of refrigeration system, but the major conclusion concerning the need for the emergency argon system is still valid. The timing of some events may change with a more accurate model but the differences between the transients with and without emergency argon will remain the same. Some of the parameters assumed in the analyses are Makeup argon supply, 18 cfm, initiates when pressure is = -6 iwg., shuts off when pressure is = -3.1 iwg. 170,000 ft3 supply. Min 1/7th always available, can be cross connected to HFEF argon supply dewar. Emergency argon supply, 900 cfm, initiates when pressure is = -8 iwg. shuts off when pressure is =-4 iwg. reservoir 220 ft3, refilled when tank farm pressure reduces to 1050 psi which is about 110 ft3.

Effects of air flow maldistribution on refrigeration system dynamics of air source heat pump chiller under frosting conditions

International Nuclear Information System (INIS)

Gong Jianying; Gao Tieyu; Yuan Xiuling; Huang Dong

2008-01-01

The effects of air flow maldistribution on the performance of an air source heat pump chiller under frosting conditions were investigated experimentally. The results indicated that air flow maldistribution was the dominant factor leading to hunting of the thermostatic expansion valve for medium and/or large size finned tube evaporators. With air flow maldistribution degree (AMD) increasing, frost occurred earlier, and the frost layer grew faster. The operating characteristics became lower when AMD was increased. We found such phenomenon seemed to be related to both the difference of refrigerant outlet superheat and the frosting velocity. In the hunting stage, the frost block effect became the main factor degrading the refrigeration system performance. With AMD increasing, the heat pump system pertinent performance data (suction pressure, evaporation temperature, discharge pressure, refrigerant outlet temperature, etc.) were degraded more dramatically

Preferential site occupancy observed in coexpanded argon-krypton clusters

International Nuclear Information System (INIS)

Lundwall, M.; Bergersen, H.; Lindblad, A.; Oehrwall, G.; Svensson, S.; Bjoerneholm, O.; Tchaplyguine, M.

2006-01-01

Free heterogeneous argon-krypton clusters have been produced by coexpansion and investigated by means of x-ray photoelectron spectroscopy. By examining cluster surface and bulk binding energy shifts, relative intensities, and peak widths, we show that in the mixed argon-krypton clusters the krypton atoms favor the bulk and argon atoms are pushed to the surface. Furthermore, we show that krypton atoms in the surface layer occupy high-coordination sites and that heterogeneous argon-krypton clusters produced by coexpansion show the same surface structure as argon host clusters doped with krypton. These observations are supported by site-dependent calculations of chemical shifts

Nowcasting in the FROST-2014 Sochi Olympic project

Science.gov (United States)

Bica, Benedikt; Wang, Yong; Joe, Paul; Isaac, George; Kiktev, Dmitry; Bocharnikov, Nikolai

2013-04-01

FROST (Forecast and Research: the Olympic Sochi Testbed) 2014 is a WMO WWRP international project aimed at development, implementation, and demonstration of capabilities of short-range numerical weather prediction and nowcasting technologies for mountainous terrain in winter season. Sharp weather contrasts and high spatial and temporal variability are typical for the region of the Sochi-2014 Olympics. Steep mountainous terrain and an intricate mixture of maritime sub-tropical and Alpine environments make weather forecasting in this region extremely challenging. Goals of the FROST-2014 project: • To develop a comprehensive information resource of Alpine winter weather observations; • To improve and exploit: o Nowcasting systems of high impact weather phenomena (precipitation type and intensity, snow levels, visibility, wind speed, direction and gusts) in complex terrain; o High-resolution deterministic and ensemble mesoscale forecasts in winter complex terrain environment; • To improve the understanding of physics of high impact weather phenomena in the region; • To deliver forecasts (Nowcasts) to Olympic weather forecasters and decision makers and assess benefits of forecast improvement. 46 Automatic Meteorological Stations (AMS) were installed in the Olympic region by Roshydromet, by owners of sport venues and by the Megafon corporation, provider of mobile communication services. The time resolution of AMS observations does not exceed 10 minutes. For a subset of the stations it is even equal to 1 min. Data flow from the new dual polarization Doppler weather radar WRM200 in Sochi was organized at the end of 2012. Temperature/humidity and wind profilers and two Micro Rain Radars (MRR) will supplement the network. Nowcasting potential of NWP models participating in the project (COSMO, GEM, WRF, AROME, HARMONIE) is to be assessed for direct and post-processed (e.g. Kalman filter, 1-D model, MOS) model forecasts. Besides the meso-scale models, the specialized

Sterile searches with Liquid Argon at FNAL

CERN Document Server

Raselli, Gian Luca

2017-01-01

A new Short Baseline Neutrino (SBN) experiment is in preparation at FNAL to definitely prove or exclude the existence of non-standard neutrino oscillations into sterile states. The program foresees the deployment along the Booster Neutrino Beam (BNB) of three detectors, all based on the liquid-argon time projection chamber technique. This technology has been taken to full maturity with ICARUS T600, which will act as far detector after the completion of the overhauling at CERN and its transportation to FNAL. The program foresees the data taking for three years.

Frost Induces Respiration and Accelerates Carbon Depletion in Trees.

Science.gov (United States)

Sperling, Or; Earles, J Mason; Secchi, Francesca; Godfrey, Jessie; Zwieniecki, Maciej A

2015-01-01

Cellular respiration depletes stored carbohydrates during extended periods of limited photosynthesis, e.g. winter dormancy or drought. As respiration rate is largely a function of temperature, the thermal conditions during such periods may affect non-structural carbohydrate (NSC) availability and, ultimately, recovery. Here, we surveyed stem responses to temperature changes in 15 woody species. For two species with divergent respirational response to frost, P. integerrima and P. trichocarpa, we also examined corresponding changes in NSC levels. Finally, we simulated respiration-induced NSC depletion using historical temperature data for the western US. We report a novel finding that tree stems significantly increase respiration in response to near freezing temperatures. We observed this excess respiration in 13 of 15 species, deviating 10% to 170% over values predicted by the Arrhenius equation. Excess respiration persisted at temperatures above 0 °C during warming and reoccurred over multiple frost-warming cycles. A large adjustment of NSCs accompanied excess respiration in P. integerrima, whereas P. trichocarpa neither excessively respired nor adjusted NSCs. Over the course of the years included in our model, frost-induced respiration accelerated stem NSC consumption by 8.4 mg (glucose eq.) cm(-3) yr(-1) on average in the western US, a level of depletion that may continue to significantly affect spring NSC availability. This novel finding revises the current paradigm of low temperature respiration kinetics.

Frost Induces Respiration and Accelerates Carbon Depletion in Trees.

Directory of Open Access Journals (Sweden)

Or Sperling

Full Text Available Cellular respiration depletes stored carbohydrates during extended periods of limited photosynthesis, e.g. winter dormancy or drought. As respiration rate is largely a function of temperature, the thermal conditions during such periods may affect non-structural carbohydrate (NSC availability and, ultimately, recovery. Here, we surveyed stem responses to temperature changes in 15 woody species. For two species with divergent respirational response to frost, P. integerrima and P. trichocarpa, we also examined corresponding changes in NSC levels. Finally, we simulated respiration-induced NSC depletion using historical temperature data for the western US. We report a novel finding that tree stems significantly increase respiration in response to near freezing temperatures. We observed this excess respiration in 13 of 15 species, deviating 10% to 170% over values predicted by the Arrhenius equation. Excess respiration persisted at temperatures above 0 °C during warming and reoccurred over multiple frost-warming cycles. A large adjustment of NSCs accompanied excess respiration in P. integerrima, whereas P. trichocarpa neither excessively respired nor adjusted NSCs. Over the course of the years included in our model, frost-induced respiration accelerated stem NSC consumption by 8.4 mg (glucose eq. cm(-3 yr(-1 on average in the western US, a level of depletion that may continue to significantly affect spring NSC availability. This novel finding revises the current paradigm of low temperature respiration kinetics.

Frosting characteristics on hydrophobic and superhydrophobic surfaces: A review

International Nuclear Information System (INIS)

Kim, Min-Hwan; Kim, Hisuk; Lee, Kwan-Soo; Kim, Dong Rip

2017-01-01

Highlights: • Fabrication methods of hydrophobic metal surfaces were investigated. • Mechanisms of ice crystal formation were reviewed in terms of static contact angle. • Future researches for frost retardation on heat exchanger surfaces were discussed. - Abstract: Fabrication methods of the hydrophobic property on metal surfaces and frosting characteristics on hydrophobic surfaces were investigated. A hydrophobic surface with a static contact angle of less than 150° was implemented by surface coating or etching, and a superhydrophobic surface with a static contact angle of greater than 150° was realized by a hybrid method using both coating and etching. The changes in surface properties affected the behaviors of the early stage frosting from the dry surface to the formation of ice crystals. On the hydrophobic surfaces, ice crystals were formed by freezing after condensation. Isolated-droplet freezing and inter-droplet freezing are mechanisms by which the condensate undergoes a phase change into ice crystals. Through isolated-droplet freezing, a supercooled condensate changes phase into ice crystals by forming ice nuclei based on the classical nucleation theory. In addition, through inter-droplet freezing, ice crystals are propagated due to the difference in saturation vapor pressure between supercooled condensates and ice crystals. The formation and propagation of ice crystals are delayed as the static contact angle increases. Additionally, based on a review, future researches that is needed to improve hydrophobic technologies are discussed.

46 CFR 151.50-36 - Argon or nitrogen.

Science.gov (United States)

2010-10-01

... 46 Shipping 5 2010-10-01 2010-10-01 false Argon or nitrogen. 151.50-36 Section 151.50-36 Shipping... BULK LIQUID HAZARDOUS MATERIAL CARGOES Special Requirements § 151.50-36 Argon or nitrogen. (a) A cargo tank that contains argon or nitrogen and that has a maximum allowable working pressure of 172 kPa (25...

Virial Coefficients for the Liquid Argon

Science.gov (United States)

Korth, Micheal; Kim, Saesun

2014-03-01

We begin with a geometric model of hard colliding spheres and calculate probability densities in an iterative sequence of calculations that lead to the pair correlation function. The model is based on a kinetic theory approach developed by Shinomoto, to which we added an interatomic potential for argon based on the model from Aziz. From values of the pair correlation function at various values of density, we were able to find viral coefficients of liquid argon. The low order coefficients are in good agreement with theoretical hard sphere coefficients, but appropriate data for argon to which these results might be compared is difficult to find.

Winter frost resistance of Pinus cembra measured in situ at the alpine timberline as affected by temperature conditions.

Science.gov (United States)

Buchner, Othmar; Neuner, Gilbert

2011-11-01

Winter frost resistance (WFR), midwinter frost hardening and frost dehardening potential of Pinus cembra L. were determined in situ by means of a novel low-temperature freezing system at the alpine timberline ecotone (1950 m a.s.l., Mt Patscherkofel, Innsbruck, Austria). In situ liquid nitrogen (LN₂)-quenching experiments should check whether maximum WFR of P. cembra belonging to the frost hardiest conifer group, being classified in US Department of Agriculture climatic zone 1, suffices to survive dipping into LN₂ (-196 °C). Viability was assessed in a field re-growth test. Maximum in situ WFR (LT₅₀) of leaves was frost hardening treatment (12 days at -20 °C followed by 3 days at -50 °C) to induce maximum WFR. Temperature treatments applied in the field significantly affected the actual WFR. In January a frost hardening treatment (21 days at -20 °C) led to a significant increase of WFR (buds: -62 °C to frost dehardening (buds: -32.6 °C to -10.2 °C; leaves: -32.7 to -16.4 °C) followed by significantly earlier bud swelling and burst in late winter. Strikingly, both temperature treatments, either increased air temperature (+10.1 °C) or increased soil temperature (+6.5 °C), were similarly effective. This high readiness to frost harden and deharden in winter in the field must be considered to be of great significance for future winter survival of P. cembra. Determination of WFR in field re-growth tests appears to be a valuable tool for critically judging estimates of WFR obtained on detached twigs in an ecological context.

Genetic engineering: frost damage trial halted.

Science.gov (United States)

Budiansky, S

The University of California at Berkeley has announced the postponement of a planned experiment involving the field testing of bacteria genetically engineered to reduce frost damage to crops. The action came after Jeremy Rifkin, who had earlier filed suit against the National Institutes of Health after its Recombinant DNA Advisory Committee had approved the experiment, threatened to seek a temporary restraining order against the university to halt the experiment.

Heat transfer and pressure drop amidst frost layer presence for the full geometry of fin-tube heat exchanger

International Nuclear Information System (INIS)

Kim, Sung Jool; Choi, Ho Jin; Ha, Man Yeong; Kim, Seok Ro; Bang, Seon Wook

2010-01-01

The present study numerically solves the flow and thermal fields in the full geometry of heat exchanger modeling with frost layer presence on the heat exchanger surface. The effects of air inlet velocity, air inlet temperature, frost layer thickness, fin pitch, fin thickness, and heat exchanger shape on the thermo-hydraulic performance of a fin-tube heat exchanger are investigated. Heat transfer rate rises with increasing air inlet velocity and temperature, and decreasing frost layer thickness and fin pitch. Pressure drop rises with increasing air inlet velocity and frost layer thickness, and decreasing fin pitch. The effect of fin thickness on heat transfer and pressure drop is negligible. Based on the present results, we derived the correlations, which express pressure drop and temperature difference between air inlet and outlet as a function of air inlet velocity and temperature, as well as frost layer thickness

Calculation of partial enthalpies in argon-krypton mixtures by NPT molecular dynamics

NARCIS (Netherlands)

Sindzingre, P.; Massobrio, C.; Ciccotti, G.; Frenkel, D.

1989-01-01

In an earlier paper, we have indicated how, by using a particle-insertion technique, partial molar enthalpies and related quantities can be evaluated from simulations on a single state point. In the present paper we apply this method to a Lennard-Jones argon-krypton mixture. For this particular

Short communication. Harvest time in hedgerow Arbequina olive orchards in areas with early frosts

Energy Technology Data Exchange (ETDEWEB)

Gracia, P.; Sanchez-Gimeno, A. C.; Benito, M.; Oria, R.; Lasa, J. M.

2012-11-01

The shortening of harvest time attained in hedgerow olive (Olea europaea L.) orchards represents an advantage for the adoption of this cropping system in areas that are prone to suffer frost during the harvest period. To establish an optimal harvesting window, we carried out a study of the fruit ripening process on a hedgerow orchard of Arbequina olive trees, located in Zaragoza (Spain). From 2007 to 2009, oil accumulation on the fruit (% of dry weight) and oil yield (grams of oil per 100 fruits) were monitored, from early September to late November. Over the three years both variables peaked around November 15th, indicating that Arbequina reached full ripening earlier than has been reported previously for this variety. In two of the three seasons the orchard suffered several frosts during November. Long term climatic data from this area indicated that the risk of early frosts (< -2 degree centigrade) increases as November progresses with a high risk after November 20{sup t}h. In conclusion, the optimal harvesting period for Arbequina in this area should not extend beyond November 20{sup t}h. A rapid harvesting before this date is advisable to avoid the risk of damage caused by early frost in Zaragoza. Hedgerow planting provides an additional advantage in frost-prone areas, because mechanization of operations permits a short harvest period, easier to fit into the optimal harvesting window. (Author) 20 refs.

The frost peat production; Routapalaturpeen tuotantoketjun tekniikka, talous ja ympaeristoevaikutukset

Energy Technology Data Exchange (ETDEWEB)

Nyroenen, T. [Vapo Oy, Jyvaeskylae (Finland); Leiviskae, V. [Oulu Univ. (Finland). Thule Inst.

1997-12-01

The frost peat production means the cutting of frozen peat in the winter time. The aim of this study is to test the possibilities to prolong the peat production season and to produce peat pieces for the horticultural peat industry. In the frost peat production method the frozen peat field is sawed throughout the length and breadth of by a circle saw. The sawed peat pieces are loosened from the field by a so-called `splitter`. The circle saw is equipped with the five circle saw blades (diameter 90 cm). The distance of the blades is adjustable. The splitter is equipped with a horizontal position blade (width 35 cm). The dimensions of the peat pieces are changeable, but from the point of drying the upper limit of the side of the peat cube can be 15-20 cm. The frost peat production method is technically suitable for production of slightly decomposed (H1-5) energy and horticultural peat. The energy peat pieces are allowed to dry up 70-75 % moisture content on the cutting field and then the pieces can be ridged by the screening ridger. If necessary, the ridges can be turned over. In the frost peat production, the conventional sod peat winning machines can be used in the following stages of the working tasks: harrowing, ridging, loading, turning of ridges and stockpiling. The measured output of the circle saw was about 45-50 m{sup 3}/h of energy peat and 58-63 m{sup 3}/h of horticultural peat. The output of the splitter was 120-150 m{sup 3}/h. Theoretically, the output of circle saw and the splitter can easily be doubled. Thereafter the production costs will be about 19 FIM/MWh of energy peat and 18,6 FIM/m{sup 3} of horticultural peat

Developing a phenological model for grapevine to assess future frost risk in Luxembourg

Science.gov (United States)

Caffarra, A.; Molitor, D.; Pertot, I.; Sinigoy, P.; Junk, J.

2012-04-01

Late frost damage represents a significant hazard to grape production in cool climate viticulture regions such as Luxembourg. The main aim of our study is to analyze the frequency of these events for the Luxembourg's winegrowing region in the future. Spring frost injuries on grape may occur when young green parts are exposed to air temperature below 0°C. The potential risk is determined by: (i) minimum air temperature conditions and the (ii) the timing of bud burst. Therefore, we developed and validated a model for budburst of the grapevine (*Vitis vinifera)* cultivar Rivaner, the most grown local variety, based on multi-annual data from 7 different sites across Europe and the US. An advantage of this approach is, that it could be applied to a wide range of climate conditions. Higher spring temperatures were projected for the future and could lead to earlier dates of budburst as well as earlier dates of last frost events in the season. However, so far it is unknown if this will increase or decrease the risk of severe late frost damages for Luxembourg's winegrowing region. To address this question results of 10 regional climate change projections from the FP6 ENSEMBLES project (spatial resolution = 25km; A1B emission scenario) were combined with the new bud burst model. The use of a multi model ensemble of climate change projections allows for a better quantification of the uncertainties. A bias corrections scheme, based on local observations, was applied to the model output. Projected daily minimum air temperatures, up to 2098, were compared to the projected date of bud burst in order to quantify the future frost risk for Luxembourg.

Air-side performance of a parallel-flow parallel-fin (PF{sup 2}) heat exchanger in sequential frosting

Energy Technology Data Exchange (ETDEWEB)

Zhang, Ping [Zhejiang Vocational College of Commerce, Hangzhou, Binwen Road 470 (China); Department of Mechanical Science and Engineering, University of Illinois at Urbana-Champaign, 1206 West Green Street, Urbana, IL 61801 (United States); Hrnjak, P.S. [Department of Mechanical Science and Engineering, University of Illinois at Urbana-Champaign, 1206 West Green Street, Urbana, IL 61801 (United States)

2010-09-15

The thermal-hydraulic performance in periodic frosting conditions is experimentally studied for the parallel-flow parallel-fin heat exchanger, henceforth referred to as a PF{sup 2} heat exchanger, a new style of heat exchanger that uses louvered bent fins on flat tubes to enhance water drainage when the flat tubes are horizontal. Typically, it takes a few frosting/defrosting cycles to come to repeatable conditions. The criterion for the initiation of defrost and a sufficiently long defrost period are determined for the test PF{sup 2} heat exchanger and test condition. The effects of blower operation on the pressure drop, frost accumulation, water retention, and capacity in time are compared under the conditions of 15 sequential frosting cycles. Pressure drop across the heat exchanger and overall heat transfer coefficient are quantified under frost conditions as functions of the air humidity and air face velocity. The performances of two types of flat-tube heat exchangers, PF{sup 2} heat exchanger and conventional parallel-flow serpentine-fin (PFSF) heat exchanger, are compared and the results obtained are presented. (author)

THE EFFECT OF CULTIVAR AND BEARING TREE ON BUD DIFFERENTIATION, FROST DAMAGE AND FRUIT SET IN APPLE

Directory of Open Access Journals (Sweden)

Nikola Pavičić

2004-06-01

Full Text Available After severe winter frost, an examination was initiated of frost damage suffered by Idared and Golden Delicious clone B. The cultivars differed significantly in the differentiation intensity, the hare of damaged differentiated buds, but not in share of damaged undifferentiated buds. In both cultivars the bud damage was more intensive on long bearing wood than on spur, regardless differentiation grade. The interaction between the cultivar and the bearing wood was insignificant. The flower bud differentiation was better in Idared, but it also suffered more frost damage than the Golden Delicious clone B with differentiated buds, but not than that with undifferentiated buds. In both cultivars frost damage increases with increase of differentiated flower buds (R2=0.759; P≤0.001. The fruit set was within the limits of expectation only on the spurs of the Golden Delicious clone B, which showed strong tendency towards fruit set on long bearing shoots. In 2000, the yield of the cultivars was almost equal, as the result of thinning due to the frost damage on Idared.

Development of a low-cost inductively coupled argon plasma

International Nuclear Information System (INIS)

Ripson, P.A.M.

1983-01-01

The aim of this investigation is to drastically reduce running costs of an inductively coupled plasma. This is done by reducing the argon consumption from 20 l/min to about 1 l/min. First, a sample introduction system operating on 0.1 l/min of carrier argon is described. This system ensures a high ratio of plasma argon and carrier argon even at the low total argon consumptions intended. Next, the developed low consumption plasma is presented. In the proposed design, air is blown perpendicularly against the outside of the torch. A different coil has been developed to make air-cooling efficient. Preliminary data on coupling efficiency for the air-cooled plasma are presented. A similarly low argon consumption has been achieved with water as an external coolant medium. It is concluded that a cheaper alternative to the current ICP has become available. (Auth.)

Argon Diffusion Measured in Rhyolite Melt at 100 MPa

Science.gov (United States)

Weldon, N.; Edwards, P. M.; Watkins, J. M.; Lesher, C. E.

2016-12-01

Argon diffusivity (D_{Ar} ) controls the rate and length scale of argon exchange between melt and gas phases and is used as a parameter to model noble gas fractionation during magma degassing. D_{Ar} may also be useful in geochronology to estimate the distribution of excess (non-radiogenic) atmospheric argon in lavas. Our measurements of D_{Ar} in molten anhydrous rhyolite near 1000 °C and 100 MPa add to the existing dataset. Using a rapid-quench cold seal pressure apparatus we exposed cylindrical charges drilled from a Miocene rhyolite flow near Buck Mtn., CA to a pure argon atmosphere resulting in a gradually lengthening argon concentration gradient between the saturated surface and the argon poor interior. Argon concentration was measured by electron microprobe along radial transects from the center to the surface of bisected samples. D_{Ar} was calculated for each transect by fitting relative argon concentration (as a function of distance from the surface) to Green's function (given each experiment's specific temperature, pressure and runtime). Variability (σ = 1.202{μm }^{2} /s) was smaller than in previous studies, but still greater than what is likely due to analytical or experimental uncertainty. We observed a symmetric geometric bias in the distribution of argon in our samples, possibly related to advective redistribution of argon accompanying the deformation of cylindrical charges into spheroids driven by surface tension. Average diffusivity, D_{Ar} = 4.791{μm }^{2} /s, is close to the predicted value, D_{Ar} = {μm }^{2} /s ( σ_{ \\bar{x} } = 1.576 {μm }^{2} /s), suggesting that Behrens and Zhang's (2001) empirical model is valid for anhydrous rhyolite melts to relatively higher temperatures and lower pressures. Behrens, H. and Y. Zhang (2001). "Ar diffusion in hydrous silicic melts: implications for volatile diffusion mechanisms and fractionation." Earth and Planetary Science Letters 192: 363-376.

Reduced-molecular-weight derivatives of frost grape polysaccharide

Science.gov (United States)

A new Type II arabinogalactan was recently described as an abundant gum exudate from stems of wildfrost grape (Vitus riparia Michx.). The purpose of the current study is to more thoroughly characterize the physical properties of this frost grape polysaccharide (FGP), and develop methods to modify th...

Role of metastable atoms in argon-diluted silane Rf plasmas

International Nuclear Information System (INIS)

Sansonnens, L.; Howling, A.A.; Hollenstein, C.; Dorier, J.L.; Kroll, U.

1994-01-01

The evolution of the argon metastable density has been studied by absorption spectroscopy in power-modulated plasmas of argon and a mixture of 4% silane in argon. A small concentration of silane suppresses the argon metastable density by molecular quenching. This molecular quenching adds to the electronic collisional dissociation to increase the silane dissociation rate as compared with pure silane plasmas. Using time-resolved emission spectroscopy, the role of metastables in excitation to the argon 2P 2 state has been determined in comparison with production from the ground state. In silane plasmas, emission from SiH* is due essentially to electron impact dissociation of silane, whereas in 4% silane-in-argon plasmas, emission from SiH* seems to be due to electron impact excitation of the SiH ground state. These studies demonstrate that argon is not simply a buffer gas but has an influence on the dissociation rate in the plasma-assisted deposition of amorphous silicon using argon-diluted silane plasmas. (author) 7 figs., 30 refs

Seasonality of cavitation and frost fatigue in Acer mono Maxim.

Science.gov (United States)

Zhang, Wen; Feng, Feng; Tyree, Melvin T

2017-12-08

Although cavitation is common in plants, it is unknown whether the cavitation resistance of xylem is seasonally constant or variable. We tested the changes in cavitation resistance of Acer mono before and after a controlled cavitation-refilling and freeze-thaw cycles for a whole year. Cavitation resistance was determined from 'vulnerability curves' showing the percent loss of conductivity versus xylem tension. Cavitation fatigue was defined as a reduction of cavitation resistance following a cavitation-refilling cycle, whereas frost fatigue was caused by a freeze-thaw cycle. A. mono developed seasonal changes in native embolisms; values were relatively high during winter but relatively low and constant throughout the growing season. Cavitation fatigue occurred and changed seasonally during the 12-month cycle; the greatest fatigue response occurred during summer and the weakest during winter, and the transitions occurred during spring and autumn. A. mono was highly resistant to frost damage during the relatively mild winter months; however, a quite different situation occurred during the growing season, as the seasonal trend of frost fatigue was strikingly similar to that of cavitation fatigue. Seasonality changes in cavitation resistance may be caused by seasonal changes in the mechanical properties of the pit membranes. © 2017 John Wiley & Sons Ltd.

CRYOLINK: Monitoring of permafrost and seasonal frost in southern Norway

Science.gov (United States)

Farbrot, Herman; Hipp, Tobias; Etzelmüller, Bernd; Humlum, Ole; Isaksen, Ketil; Strand Ødegârd, Rune

2010-05-01

The modern southern boundary for Scandinavian permafrost is located in the mountains of Southern Norway. Permafrost and seasonal frost are considered key components of the cryosphere, and the climate-permafrost relation has acquired added importance with the increasing awareness and concern of rising air temperatures. The three-year research project CRYOLINK ("Permafrost and seasonal frost in southern Norway") aims at improving knowledge on past and present ground temperatures, seasonal frost, and distribution of mountain permafrost in Southern Norway by addressing the fundamental problem of heat transfer between the atmosphere and the ground surface. Hence, several shallow boreholes have been drilled in August 2008 in three areas (Juvvass, Jetta and Tron) situated along a west-east transect. On most borehole sites air and ground temperatures are measured. Further, vertical arrays of Miniature Temperature Dataloggers (MTDs; Thermochron iBottons®) at fixed heights above the ground surface have been installed to roughly determine the snow depths at the sites, which is also indicated by digital cameras providing daily pictures of snow and weather conditions. In addition individual MTDs have been placed out to measure ground surface temperature at different aspects and snow settings. This presentation will focus on the field set up and give examples of data obtained from the sites.

Frost resistance of building materials

DEFF Research Database (Denmark)

Hansen, Ernst Jan De Place

materials, has been developed.The importance of the pore structure on the development of stresses in the material during freezing is emphasized. To verify the model, experimental investigations are made on various concretes without air-entrainment and brick tiles with different porosities.Calculations......In this thesis it is shown that the critical degree of saturation is suitable as parameter for the frost resistance of porous building materials. A numerical model for prediction of critical degrees of saturation based on fracture mechanics and phase geometry of two-phase materials, e.g. porous...

Measurement of argon concentrations in a TRIGA Mark-III pool

Energy Technology Data Exchange (ETDEWEB)

Simms, R [California State University, Northridge, CA (United States)

1974-07-01

Argon-41, the principal radioactive effluent from a pool type reactor during normal operation, is produced by the {sup 40}A (n,{gamma}) reaction. The reactant, {sup 40}A, is introduced into the pool water by contact with the air. Reduction in radioactive argon release can be accomplished by reducing the concentration of dissolved {sup 40}A and retaining the {sup 41}A within the pool. However, little data were available concerning the mechanisms of argon introduction, production, retention, and release from a reactor pool. Experiments have therefore been performed at the Torrey Pines TRIGA Mark-III Reactor to develop techniques to sample dissolved argon and to provide data on argon concentrations in the pool for release modeling studies. Significant results for argon dissolved at different pool depths can only be obtained if the water samples are sealed at the point of collection. A special handling tool was developed to perform this remote operation. Pool samples were counted for {sup 41}A soon after collection with a NaI spectrometer. After allowing one day for decay of {sup 41}A, the concentration of {sup 40}A in the water sample was determined by neutron activation analysis. In each case, the 1.29 MeV gamma-ray peak of {sup 41}A was used. Interference from the 1.37 MeV {sup 24}Na peak was considered and its effect subtracted after determining {sup 24}Na content from the 2.75 MeV {sup 24}Na peak and a sodium standard. A Ge(Li) detector was tried and found to eliminate the problem, but it introduced an unacceptable geometrical effect dependent on bubble size within the sample bottles. Samples were taken from the 27 ft deep TRIGA pool at various locations. Results were obtained for samples taken on several different days along the same vertical line about 3-1/2 ft from the reactor centerline. Temperature measurements along this vertical traverse indicated a sharp temperature gradient at about 15 ft below the surface ({approx}6 ft above the top of the reactor). The

Limited mobility of argon in a metamorphic terrain

Energy Technology Data Exchange (ETDEWEB)

Foland, K A [Pennsylvania Univ., Philadelphia (USA). Dept. of Geology

1979-06-01

Excess /sup 40/Ar in biotite from some relatively anhydrous charnockitic rocks in the Appalachian Piedmont indicates limited mobility or argon. Biotite from the Arden pluton of the granulite-facies Wilmington Complex apparently formed as a retrograde product at the expense of pyroxene and K-feldspar Rb-Sr ages of biotite from all rocks are approximately 365 Myr. The same micas have apparent K-Ar ages which range from about 365-590 Mye, six of which clearly exceed the Sr isotope whole-rock date of 500 Myr. They contain variable amounts of excess /sup 40/Ar incorporated during crystallization or recrystallization of biotite at about 365 Myr ago. None of the other minerals appears to contain significant amounts of excess argon. The K-Ar apparent ages show strong, positive correlation with whole-rock K concentrations. These relations yield a correlation between excess argon in the biotite phase and rock potassium. This suggests that excess /sup 40/Ar in biotite is of local derivation and is due to an imprint of the local argon activity. If the amount incorporated is roughly proportional to the prevailing argon partial pressure then substantial differences in psub(Ar) existed. Argon did not have a uniform chemical potential over large rock volumes. Analysis of closely spaced samples suggests different argon activity over the scale of less than 10 m. This implies restricted transport of Ar and is probably due to very low effective permeability of the anhydrous assemblages.

Making a case for breeding frost tolerant potatoes adapted to Andean Highlands especially the Altiplano

Science.gov (United States)

Although cultivated potatoes are sensitive to mild frost (severely damaged at air temperatures below -2 or -3 C) limited progress has been made in developing frost hardy cultivars. This may be due to the fact that most potato crop grown in North America and Europe has minimal risk to be subjected to...

Past and future changes in frost day indices on Catskill Mountain Region of New York

Science.gov (United States)

Changes in frost indices in the New York’s Catskill Mountains region, the location of water supply reservoirs for New York City, have potentially important implications. Frost day is defined as a day with Tmin < 0ºC. The objective of this study was to investigate past and predicted changes in minimu...

Pressure regulation in the dry-boxes. Argon purification; Regulation de pression dans les boites a gants. Purification d'argon

Energy Technology Data Exchange (ETDEWEB)

Pascard, R; Fabre, R [Commissariat a l' Energie Atomique, Saclay (France). Centre d' Etudes Nucleaires

1958-07-01

Each dry-box is equipped with an autonomous installation for circulation and purification of argon and for pressure regulation. This installation consists essentially of a ballast tank, a compressor and two valves electromagnetically controlled by a contact manometer. The compressor and the valves are enclosed in the tank to form a system as compact as possible. The argon is purified by passing it over a furnace filled with titanium-zirconium turnings brought to about 800 deg. C, branching off the main system. With this set-up as well as the automatic maintenance of a constant depression in the box, a quality of argon is obtained whose oxygen contact is undetectable by the manganous hydroxide method. (author) [French] Chaque boite a gants est munie d'une installation autonome de circulation purification d'argon et de regulation de pression. Cette installation comprend essentiellement un reservoir tampon, un compresseur et deux vannes electromagnetiques commandees par un manometre a contact. Le compresseur et les vannes sont enfermes dans le reservoir de maniere a realiser un ensemble aussi compact que possible. L'argon est purifie par passage dans un four en derivation charge de tournure de titane-zirconium, porte a environ 800 deg. C. Avec ce dispositif, on obtient, outre le maintien automatique d'une depression constante dans la boite, un argon dont la teneur en oxygene est indecelable par la methode a l'hydrate manganeux. (auteur)

Severe soil frost reduced losses of carbon and nitrogen from the forest floor during simulated snowmelt: A laboratory experiment

Science.gov (United States)

Andrew B. Reinmann; Pamela H. Templer; John L. Campbell

2012-01-01

Considerable progress has been made in understanding the impacts of soil frost on carbon (C) and nitrogen (N) cycling, but the effects of soil frost on C and N fluxes during snowmelt remain poorly understood. We conducted a laboratory experiment to determine the effects of soil frost on C and N fluxes from forest floor soils during snowmelt. Soil cores were collected...

Development of a Frost Risk Assessment Tool in Agriculture for a Mediterranean ecosystem Utilizing MODIS satellite observations Geomatics and Surface Data

Science.gov (United States)

Louka, Panagiota; Papanikolaou, Ioannis; Petropoulos, George; Migiros, George; Tsiros, Ioannis

2014-05-01

Frost risk in Mediterranean countries is a critical factor in agricultural planning and management. Nowadays, the rapid technological developments in Earth Observation (EO) technology have improved dramatically our ability to map the spatiotemporal distribution of frost conditions over a given area and evaluate its impacts on the environment and society. In this study, a frost risk model for agricultural crops cultivated in a Mediterranean environment has been developed, based primarily on Earth Observation (EO) data from MODIS sensor and ancillary spatial and point data. The ability of the model to predict frost conditions has been validated for selected days on which frost conditions had been observed for a region in Northwestern Greece according to ground observations obtained by the Agricultural Insurance Organization (ELGA). An extensive evaluation of the frost risk model predictions has been performed herein to evaluate objectively its ability to predict the spatio-temporal distribution of frost risk in the studied region, including comparisons against physiographical factors of the study area. The topographical characteristics that were taken under consideration were latitude, altitude, slope steepness, topographic convergence and the extend of the areas influenced by water bodies (such as lake and sea) existing in the study area. Additional data were also used concerning land use data and vegetation classification (type and density). Our results showed that the model was able to produce reasonably the spatio-temporal distribution of the frost conditions in our study area, following largely explainable patterns in respect to the study site and local weather conditions characteristics. All in all, the methodology implemented herein proved capable in obtaining rapidly and cost-effectively cartography of the frost risk in a Mediterranean environment, making it potentially a very useful tool for agricultural management and planning. The model presented here has

SLD liquid argon calorimeter

International Nuclear Information System (INIS)

Vella, E.

1992-10-01

The liquid argon calorimeter (LAC) of the SLD detector is a parallel plate -- liquid argon sampling calorimeter, used to measure particle energies in Z 0 decays at the Stanford Linear Collider. The LAC module design is based on a unique projective tower structure, in which lead plates and segmented lead tiles serve both as absorbers and electrodes. The LAC front end electronics incorporates several novel features, including extensive multiplexing and optical fiber readout, which take advantage of the low SLC beam crossing frequency. The operational performance of the LAC during the recently completed SLD physics run (which recorded over 10,000 Z 0 events) is discussed

Analysis of heat transfer and frost layer formation on a cryogenic tank wall exposed to the humid atmospheric air

International Nuclear Information System (INIS)

Kim, Kyoung-Hoon; Ko, Hyung-Jong; Kim, Kyoungjin; Kim, Yong-Wook; Cho, Kie-Joo

2009-01-01

In this paper heat transfer characteristics and frost layer formation are investigated numerically on the surface of a cryogenic oxidizer tank for a liquid propulsion rocket, where a frost layer could be a significant factor in maintaining oxidizer temperature within a required range. Frost formation is modeled by considering mass diffusion of water vapor in the air into the frost layer and various heat transfer modes such as natural and forced convection, latent heat, solar radiation of short wavelength, and ambient radiation of long wavelength. Computational results are first compared with the available measurements and show favorable agreement on thickness and effective thermal conductivity of the frost layer. In the case of the cryogenic tank, a series of parametric studies is presented in order to examine the effects of important parameters such as temperature and wind speed of ambient air, air humidity, and tank wall temperature on the frost layer formation and the amount of heat transfer into the tank. It is found that the heat transfer by solar radiation is significant and also that heat transfer strongly depends on air humidity, ambient air temperature, and wind speed but not tank wall temperature.

Use of LST images from MODIS/AQUA sensor as an indication of frost occurrence in RS

Directory of Open Access Journals (Sweden)

Débora de S. Simões

2015-10-01

Full Text Available ABSTRACTAlthough frost occurrence causes severe losses in agriculture, especially in the south of Brazil, the data of minimum air temperature (Tmin currently available for monitoring and predicting frosts show insufficient spatial distribution. This study aimed to evaluate the MDY11A1 (LST – Land Surface Temperature product, from the MODIS sensor on board the AQUA satellite as an estimator of frost occurrence in the southeast of the state of Rio Grande do Sul, Brazil. LST images from the nighttime overpass of the MODIS/AQUA sensor for the months of June, July and August from 2006 to 2012, and data from three conventional weather stations of the National Institute of Meteorology (INMET were used. Consistency was observed between Tmin data measured in weather stations and LST data obtained from the MODIS sensor. According to the results, LSTs below 3 ºC recorded by the MODIS/AQUA sensor are an indication of a favorable scenario to frost occurrence.

Assessing Wheat Frost Risk with the Support of GIS: An Approach Coupling a Growing Season Meteorological Index and a Hybrid Fuzzy Neural Network Model

Directory of Open Access Journals (Sweden)

Yaojie Yue

2016-12-01

Full Text Available Crop frost, one kind of agro-meteorological disaster, often causes significant loss to agriculture. Thus, evaluating the risk of wheat frost aids scientific response to such disasters, which will ultimately promote food security. Therefore, this paper aims to propose an integrated risk assessment model of wheat frost, based on meteorological data and a hybrid fuzzy neural network model, taking China as an example. With the support of a geographic information system (GIS, a comprehensive method was put forward. Firstly, threshold temperatures of wheat frost at three growth stages were proposed, referring to phenology in different wheat growing areas and the meteorological standard of Degree of Crop Frost Damage (QX/T 88-2008. Secondly, a vulnerability curve illustrating the relationship between frost hazard intensity and wheat yield loss was worked out using hybrid fuzzy neural network model. Finally, the wheat frost risk was assessed in China. Results show that our proposed threshold temperatures are more suitable than using 0 °C in revealing the spatial pattern of frost occurrence, and hybrid fuzzy neural network model can further improve the accuracy of the vulnerability curve of wheat subject to frost with limited historical hazard records. Both these advantages ensure the precision of wheat frost risk assessment. In China, frost widely distributes in 85.00% of the total winter wheat planting area, but mainly to the north of 35°N; the southern boundary of wheat frost has moved northward, potentially because of the warming climate. There is a significant trend that suggests high risk areas will enlarge and gradually expand to the south, with the risk levels increasing from a return period of 2 years to 20 years. Among all wheat frost risk levels, the regions with loss rate ranges from 35.00% to 45.00% account for the largest area proportion, ranging from 58.60% to 63.27%. We argue that for wheat and other frost-affected crops, it is

Hygro thermal simulation to predict the risk of frost damage in masonry : effects of climate change

NARCIS (Netherlands)

van Aarle, M.A.P.; Schellen, H.L.; van Schijndel, A.W.M.

2015-01-01

According to the Royal Netherlands Meteorological Institute (KNMI) climate change will result in an increase of air temperature and rainfall intensities for the Netherlands in winter in future. In this paper we investigate the effect of the risk of frost damage to masonry. The risk of frost damage

Modelling electroluminescence in liquid argon

International Nuclear Information System (INIS)

Stewart, D Y; Barker, G J; Bennieston, A J; Harrison, P F; McConkey, N; Morgan, B; Ramachers, Y A; Lightfoot, P K; Robinson, M; Spooner, N J C; Thompson, L

2010-01-01

We present Monte-Carlo simulations of electron transport through liquid argon motivated by our recent observation of electroluminescence light emanating from a thick gaseous electron multiplier (THGEM) in a liquid argon volume. All known elastic and inelastic reaction cross-sections have been accounted for, providing electroluminescence light yield predictions for arbitrary electrostatic fields. This study concludes that the large field gradients needed to produce electroluminescence cannot be accounted for by straightforward electrostatic field calculations based on ideal THGEM holes, suggesting that further experimental investigations are required.

Two-photon excitation of argon

International Nuclear Information System (INIS)

Pindzola, P.S.; Payne, M.C.

1982-01-01

The authors calculate two photon excitation parameters for various excited states of argon assuming the absorption of near resonance broad-bandwidth laser radiation. Results are given for the case of two photons absorbed for the same laser beam as well as the case of absorbing photons of different frequency from each of two laser beams. The authors use multiconfiguration Hartree-Fock wave functions to evaluate the second-order sums over matrix elements. Various experimental laser schemes are suggested for the efficient excitation and subsequent ionization of argon

ArgonCube: a Modular Approach for Liquid Argon TPC Neutrino Detectors for Near Detector Environments

CERN Document Server

Auger, M; Sinclair, JR

2017-01-01

Liquid Argon Time Projection Chambers (LAr TPCs) are an ideal detector candidate for future neutrino oscillation physics experiments, underground neutrino observatories and proton decay searches. A large international project based on this technology is currently under consideration at the future LBNF/DUNE facility in the United States. That particular endeavor would be on the very large mass scale of 40~kt. Following diverse and long standing R\\&D work conducted over several years, with contributions from international collaborators, we propose a novel LAr TPC based on a fully-modular, innovative design, ArgonCube. ArgonCube will demonstrate that LAr TPCs are a viable detector technology for high-energy and high-multiplicity environments, such as the DUNE near detector. Necessary R\\&D work is proceeding along two main pathways; the first, aimed at the demonstration of modular detector design and the second, at the exploration of new signal readout methods. This two-pronged approach has provided a hig...

Presidential Green Chemistry Challenge: 1998 Academic Award (Draths and Frost)

Science.gov (United States)

Presidential Green Chemistry Challenge 1998 award winners, Dr. Karen M. Draths and Professor John W. Frost, used benign, genetically engineered microbes and sugars (instead of benzene) to synthesize adipic acid and catechol.

Aging tests of ethylene contaminated argon/ethane

International Nuclear Information System (INIS)

Atac, M.; Bauer, G.

1994-01-01

We report on aging tests of argon/ethane gas with a minor (1800 ppM) component of ethylene. The measurements were first conducted with the addition of alcohol to test the suppression of aging by this additive, with exposure up to ∼1.5 C/cm. Tests have included: a proportional tube with ethanol, another with isopropyl alcohol, and for comparison a tube has also been run with ethanol and argon/ethane from CDF's old (ethylene-free) ethane supply. The aging test with ethanol showed no difference between the ethylene-free and the ethylene tube. Furthermore, raw aging rates of argon/ethane and argon/ethane/ethylene were measured by exposing tubes without the addition of alcohol to about 0.1 C/cm. Again, no significant difference was observed. In conclusion, we see no evidence that ethylene contamination up to 1800 ppM has any adverse effect on wire aging. However, this level of ethylene does seem to significantly suppress the gas gain

Contraction ionization waves in the argon contracted discharge

International Nuclear Information System (INIS)

Golubovskij, Yu.B.; Kulikov, V.V.; Nekutchaev, V.O.

1985-01-01

An investigation of ionization waves in the argon contracted discharge and a definition of their arising propagation mechanism accounting for the specificity of elementary pocesses characteristic of argon are presented. (author)

Development of a low frost-point generator operating at sub-atmospheric pressure

Science.gov (United States)

Cuccaro, R.; Rosso, L.; Smorgon, D.; Beltramino, G.; Tabandeh, S.; Fernicola, V.

2018-05-01

A low frost-point generator (INRIM 03) operating at sub-atmospheric pressure has been designed and constructed at the Istituto Nazionale di Ricerca Metrologica (INRIM) as part of a calibration facility for upper-air sounding instruments. This new humidity generator covers the frost-point temperature range between  ‑99 °C and  ‑20 °C and works at any controlled pressure between 200 hPa and 1100 hPa, achieving a complete saturation of the carrier gas (nitrogen) in a single passage through a stainless steel isothermal saturator. The generated humid gas contains a water vapour amount fraction between 14  ×  10‑9 mol mol‑1 and 5  ×  10‑3 mol mol‑1. In this work the design of the generator is reported together with characterisation and performance evaluation tests. A preliminary validation of the INRIM 03 against one of the INRIM humidity standards in the common region is also included. Based on experimental test results, an initial uncertainty evaluation of the generated frost-point temperature, T fp, and water vapour amount fraction, x w, in the limited range down to  ‑75 °C at atmospheric pressure is reported. For the frost-point temperature, the uncertainty budget yields a total expanded uncertainty (k  =  2) of less than 0.028 °C, while for the mole fraction the budget yields a total expanded uncertainty of less than 10‑6 mol mol‑1.

Frosted branch angiitis, neuroretinitis as initial ocular manifestation in Behçet disease

Directory of Open Access Journals (Sweden)

Abdullah Al-Mujaini

2011-01-01

Full Text Available Behçet disease is an idiopathic, multisystem disorder characterized by recurrent episodes of orogenital ulceration and vasculitis of the veins and arteries of all calibers. Ocular involvement may affect the conjunctiva, sclera, uveal tract, vitreous, blood vessels, and retina. Many theories have pointed toward an autoimmune response behind its pathogenesis, which may be triggered by exposure to an infectious agent. Frosted branch angiitis is characterized by vascular inflammation, sheathing, retinal edema, and retinal hemorrhages. The disease may be idiopathic in a majority of the cases or may be associated with ocular and systemic pathology. Association between Behηet disease, Frosted branch angiitis, and neuroretinitis is not reported in literature. This uncommon combination reflects the varied systemic and ocular manifestations in Behηet disease, especially in patients who are not diagnosed and treated in time. We hereby report a case of bilateral frosted branch angiitis and neuroretinitis in a young male from Middle-east, suffering from Behçet disease.

Frost Heave in Colloidal Soils

KAUST Repository

Peppin, Stephen

2011-01-01

We develop a mathematical model of frost heave in colloidal soils. The theory accountsfor heave and consolidation while not requiring a frozen fringe assumption. Two solidificationregimes occur: a compaction regime in which the soil consolidates to accommodate the ice lenses, and a heave regime during which liquid is sucked into the consolidated soil from an external reservoir, and the added volume causes the soil to heave. The ice fraction is found to vary inversely with thefreezing velocity V , while the rate of heave is independent of V , consistent with field and laboratoryobservations. © 2011 Society for Industrial and Applied Mathematics.

GC13I-0857: Designing a Frost Forecasting Service for Small Scale Tea Farmers in East Africa

Science.gov (United States)

Adams, Emily C.; Wanjohi, James Nyaga; Ellenburg, Walter Lee; Limaye, Ashutosh S.; Mugo, Robinson M.; Flores Cordova, Africa Ixmucane; Irwin, Daniel; Case, Jonathan; Malaso, Susan; Sedah, Absae

2017-01-01

Kenya is the third largest tea exporter in the world, producing 10% of the world's black tea. Sixty percent of this production occurs largely by small scale tea holders, with an average farm size of 1.04 acres, and an annual net income of $1,075. According to a recent evaluation, a typical frost event in the tea growing region causes about $200 dollars in losses which can be catastrophic for a small holder farm. A 72-hour frost forecast would provide these small-scale tea farmers with enough notice to reduce losses by approximately 80 USD annually. With this knowledge, SERVIR, a joint NASA-USAID initiative that brings Earth observations for improved decision making in developing countries, sought to design a frost monitoring and forecasting service that would provide farmers with enough lead time to react to and protect against a forecasted frost occurrence on their farm. SERVIR Eastern and Southern Africa, through its implementing partner, the Regional Centre for Mapping of Resources for Development (RCMRD), designed a service that included multiple stakeholder engagement events whereby stakeholders from the tea industry value chain were invited to share their experiences so that the exact needs and flow of information could be identified. This unique event allowed enabled the design of a service that fit the specifications of the stakeholders. The monitoring service component uses the MODIS Land Surface Temperature product to identify frost occurrences in near-real time. The prediction component, currently under testing, uses the 2-m air temperature, relative humidity, and 10-m wind speed from a series of high-resolution Weather Research and Forecasting (WRF) numerical weather prediction model runs over eastern Kenya as inputs into a frost prediction algorithm. Accuracy and sensitivity of the algorithm is being assessed with observations collected from the farmers using a smart phone app developed specifically to report frost occurrences, and from data shared

The risk of early and late frost behavior in central México under El Niño conditions

OpenAIRE

PERALTA-HERNÁNDEZ, A. R; BARBA-MARTÍNEZ, L. R

2009-01-01

The irregular occurrence of cold temperatures (frost) in central México (~19-23° N) produces high agricultural losses each year; the greatest effect is on cold-sensitive crops, which has important socio-economic implications for the region. There is a lack of information on frost-related studies regarding the onset and duration of frosts in central México, especially in response to the El Niño (EN) phenomenon. Due to the land's irregular topography, the weather stations were grouped into 300 ...

Isentropic Compression of Argon

International Nuclear Information System (INIS)

Oona, H.; Solem, J.C.; Veeser, L.R.; Ekdahl, C.A.; Rodriquez, P.J.; Younger, S.M.; Lewis, W.; Turley, W.D.

1997-01-01

We are studying the transition of argon from an insulator to a conductor by compressing the frozen gas isentropically to pressures at which neighboring atomic orbitals overlap sufficiently to allow some electron motion between atoms. Argon and the other rare gases have closed electron shells and therefore remain montomic, even when they solidify. Their simple structure makes it likely that any measured change in conductivity is due to changes in the atomic structure, not in molecular configuration. As the crystal is compressed the band gap closes, allowing increased conductivity. We have begun research to determine the conductivity at high pressures, and it is our intention to determine the compression at which the crystal becomes a metal

Chlorophyll fluorescence as a parameter for frost hardiness in winter wheat. A comparison with other hardiness parameters.

NARCIS (Netherlands)

Clement, JMAM; vanHasselt, PR

1996-01-01

Frost hardiness of winter wheat leaves (Triticum aestivum L. cv. Urban) was measured during an eight weeks hardening period using chlorophyll fluorescence. Determination of frost induced damage after freezing, measured as the decrease of photochemical capacity of photosystem II (F-V/F-M =

Influence of coffee pruning on the severity of frost damage

Directory of Open Access Journals (Sweden)

Armando Androcioli Filho

2000-01-01

Full Text Available Frost damages in a field experiment of pruning types and systems for the cultivars of Coffea arabica Catuaí and Mundo Novo, were evaluated at Londrina (23º22’S, 52º10´W, State of Parana, southern Brazil, during the winter of 1990 and 1994. Pruning types evaluated were ‘esqueletamento’ (cutting off all plagiotropic branches at 20-30 cm from the orthotropic branch, ‘decote’ (cutting off the orthotropic branch at 1.5 m and 2.0 m above ground and ‘recepa’ (cutting off the orthotropic branch at 0.8 m above ground, performed on all rows and on alternate rows, and on different sections of the plant. Results indicated that frost damage could increase according to the type and height of pruning. The pruning type ‘esqueletamento’ and prunings at higher levels were more suitable for regions with frost risk. Under severe frost condition, pruning type did not affect the damage in anyone of the treatments evaluated.Foram avaliados os danos causados pelas geadas ocorridas em 1990 e 1994 em cafeeiros de duas cultivares de Coffea arabica L., Catuaí e Mundo Novo, conduzidos em Londrina-PR. Os tipos e sistemas de podas aplicados foram o esqueletamento a 20-30 cm do tronco, decote a 1,5 m e 2,0 m de altura e recepa a 0,80 m de altura. As podas foram feitas em área total e em linhas alternadas e em diferentes partes da planta. Os dados obtidos indicaram que os danos por geada podem ser intensificados em função do tipo e altura da poda. A poda do tipo esqueletamento e as podas altas são mais indicadas para o manejo das lavouras nas regiões mais sujeitas ao fenômeno de geada. No caso de geada severa, todos os cafeeiros foram afetados, independente do tipo de poda.

Distribution of pines in the Iberian Peninsula agrees with species differences in foliage frost tolerance, not with vulnerability to freezing-induced xylem embolism.

Science.gov (United States)

Fernández-Pérez, Laura; Villar-Salvador, Pedro; Martínez-Vilalta, Jordi; Toca, Andrei; Zavala, Miguel A

2018-04-01

Drought and frosts are major determinants of plant functioning and distribution. Both stresses can cause xylem embolism and foliage damage. The objective of this study was to analyse if the distribution of six common pine species along latitudinal and altitudinal gradients in Europe is related to their interspecific differences in frost tolerance and to the physiological mechanisms underlying species-specific frost tolerance. We also evaluate if frost tolerance depends on plant water status. We studied survival to a range of freezing temperatures in 2-year-old plants and assessed the percentage loss of hydraulic conductivity (PLC) due xylem embolism formation and foliage damage determined by needle electrolyte leakage (EL) after a single frost cycle to -15 °C and over a range of predawn water potential (ψpd) values. Species experiencing cold winters in their range (Pinus nigra J.F. Arnold, Pinus sylvestris L. and Pinus uncinata Raymond ex A. DC.) had the highest frost survival rates and lowest needle EL and soluble sugar (SS) concentration. In contrast, the pines inhabiting mild or cool winter locations (especially Pinus halepensis Mill. and Pinus pinea L. and, to a lesser extent, Pinus pinaster Ait.) had the lowest frost survival and highest needle EL and SS values. Freezing-induced PLC was very low and differences among species were not related to frost damage. Reduction in ψpd decreased leaf frost damage in P. pinea and P. sylvestris, increased it in P. uncinata and had a neutral effect on the rest of the species. This study demonstrates that freezing temperatures are a major environmental driver for pine distribution and suggests that interspecific differences in leaf frost sensitivity rather than vulnerability to freezing-induced embolism or SS explain pine juvenile frost survival.

Argon isotopes as recorders of magmatic processes

Science.gov (United States)

Layer, P. W.; Gardner, J. E.; Mora Chaparro, J. C.; Arce, J. L.

2003-12-01

Argon isotopic ratios vary enough between different reservoirs (atmosphere, crust, mantle) and diffuse fast enough through most minerals at magmatic temperatures (700-1200 C) to make them ideal for looking at magma chamber dynamics. Indeed, diffusion is sufficiently fast to allow short time scales to be deciphered, setting argon apart from many other isotopic methods. A mineral's ability to retain "excess" argon (40Ar/36Ar ratios greater than the atmospheric value and apparent ages older than the known eruption age) during post-eruption cooling is key to Ar studies. Previous work shows that both phenocrysts (crystallizing in the magma chamber; e.g. Mt St. Helens; Layer and Gardner, 2001) and xenocrysts (introduced into the magma chamber; e.g Toba; Gardner et al., 2002) preserve excess argon, which enables magma chamber processes to be deciphered through the variable diffusion rates between crystal phases. Single crystal 40Ar/39Ar step-heating of biotite from the 10.5 ka eruption of Nevado de Toluca volcano, Mexico indicates that they are xenocrystic and resided for only a short (< 1 year) time in the magma before it erupted. The biotite has reaction rims of hornblende, orthopyroxene and plagioclase, and failed to grow experimentally at pressure-temperature conditions of the magma, confirming the xenocrystic nature of this phase. Single-step fusion of plagioclase phenocrysts from eruptions of El Chichon volcano, Mexico, shows evidence of excess (mantle) argon, whereas hornblende from the same eruptions contains little or none. In this case, faster diffusion of Ar in plagioclase than in hornblende allow plagioclase to incorporate excess argon during magma recharge; hornblende does not. Combining such results with other isotopic systems may in fact better determine magma chamber processes. At El Chichon, Sr isotopes suggest magma recharges ocurred (Tepley et al., 2000), whereas the argon isotopes suggest such pulses occurred just before each eruption. The fast and

The argon excimer laser

International Nuclear Information System (INIS)

Wrobel, W.G.

1981-02-01

The electron-beam-pumped argon eximer laser is investigated and tuned for the first time. The electron beam is generated by means of an improved coaxial field emmision diode in which argon gas is excited with power densities of 0.3 GW/cm 3 for 18 ns. The processes in the excited gas of 20 to 65 bar are described in the context of a kinetic model as a sequence of stationary states. Investigations of the amplified spontaneous emission (superfluorescence) confirm the predictions of this model. Only the absorption due to the excited Ar atoms is anomalously high. Reproducible operation of the argon eximer laser was achieved in a wide pressure range with various resonator arrangements. The wavelength of this shortest wavelength of this shortest wavelength excimer laser is 126 nm, the laser line width approx. 1.7 nm, the pulse length 7 to 13 ns, and the laser power 250 kW. The laser emission is tuned from 123.2 nm to 128.4 nm by two different methods (diffraction grating and prism). This tunable laser is thus the one with the shortest wavelength at present. Its line width is 0.25 to 0.4 nm, and the power ue 1.7 kW. (orig.)

Changing risk of spring frost damage in grapevines due to climate change? A case study in the Swiss Rhone Valley.

Science.gov (United States)

Meier, Michael; Fuhrer, Jürg; Holzkämper, Annelie

2018-06-01

Late spring frost is a severe risk during early plant development. It may cause important economic damage to grapevine production. In a warming climate, late frost risk either could decline due to the reduction in frost days and an advancement of the last day of frost or increase due to a more pronounced shift forward of the start of the active growing period of the plants. These possibilities were analyzed in a case study for two locations in the lower Swiss Rhone Valley (Sion, Aigle) where viticulture is an important part of agriculture. Twelve phenology models were calibrated for the developmental stage BBCH09 (bud burst) using measured or reconstructed temperature data for two vineyards in Changins (1958 to 2012) and Leytron (1977 to 2014) together with observed phenological data. The day of year (DOY) for BBCH09 was then modelled for the years 1951 to 2050 using the best performing phenology model in combination with ten downscaled and bias-corrected climate scenarios. A 100-day period starting with BBCH09 was defined, during which daily mean and minimum temperatures were used to calculate three frost risk indices in each year. These indices were compared between the periods 1961-1990 (reference) and 2021-2050 (climate change scenario). Based on the average of the ensemble of climate model chains, BBCH09 advanced by 9 (range 7-11) (Aigle) and 7 (range 5-8) (Sion) days between the two time periods, similar to the shift in the last day of frost. The separate results of the different model chains suggest that, in the near future, late spring frost risk may increase or decrease, depending on location and climate change projections. While for the reference, the risk is larger at the warmer site (Sion) compared to that at the cooler site (Aigle), for the period 2021-2050, small shifts in both phenology and occurrence of frost (i.e., days with daily minimum temperature below 0 °C) lead to a small decrease in frost risk at the warmer but an increase at the cooler

Changing risk of spring frost damage in grapevines due to climate change? A case study in the Swiss Rhone Valley

Science.gov (United States)

Meier, Michael; Fuhrer, Jürg; Holzkämper, Annelie

2018-01-01

Late spring frost is a severe risk during early plant development. It may cause important economic damage to grapevine production. In a warming climate, late frost risk either could decline due to the reduction in frost days and an advancement of the last day of frost or increase due to a more pronounced shift forward of the start of the active growing period of the plants. These possibilities were analyzed in a case study for two locations in the lower Swiss Rhone Valley (Sion, Aigle) where viticulture is an important part of agriculture. Twelve phenology models were calibrated for the developmental stage BBCH09 (bud burst) using measured or reconstructed temperature data for two vineyards in Changins (1958 to 2012) and Leytron (1977 to 2014) together with observed phenological data. The day of year (DOY) for BBCH09 was then modelled for the years 1951 to 2050 using the best performing phenology model in combination with ten downscaled and bias-corrected climate scenarios. A 100-day period starting with BBCH09 was defined, during which daily mean and minimum temperatures were used to calculate three frost risk indices in each year. These indices were compared between the periods 1961-1990 (reference) and 2021-2050 (climate change scenario). Based on the average of the ensemble of climate model chains, BBCH09 advanced by 9 (range 7-11) (Aigle) and 7 (range 5-8) (Sion) days between the two time periods, similar to the shift in the last day of frost. The separate results of the different model chains suggest that, in the near future, late spring frost risk may increase or decrease, depending on location and climate change projections. While for the reference, the risk is larger at the warmer site (Sion) compared to that at the cooler site (Aigle), for the period 2021-2050, small shifts in both phenology and occurrence of frost (i.e., days with daily minimum temperature below 0 °C) lead to a small decrease in frost risk at the warmer but an increase at the cooler

Behavior of Excited Argon Atoms in Inductively Driven Plasmas

International Nuclear Information System (INIS)

HEBNER, GREGORY A.; MILLER, PAUL A.

1999-01-01

Laser induced fluorescence has been used to measure the spatial distribution of the two lowest energy argon excited states, 1s 5 and 1s 4 , in inductively driven plasmas containing argon, chlorine and boron trichloride. The behavior of the two energy levels with plasma conditions was significantly different, probably because the 1s 5 level is metastable and the 1s 4 level is radiatively coupled to the ground state but is radiation trapped. The argon data is compared with a global model to identify the relative importance of processes such as electron collisional mixing and radiation trapping. The trends in the data suggest that both processes play a major role in determining the excited state density. At lower rfpower and pressure, excited state spatial distributions in pure argon were peaked in the center of the discharge, with an approximately Gaussian profile. However, for the highest rfpowers and pressures investigated, the spatial distributions tended to flatten in the center of the discharge while the density at the edge of the discharge was unaffected. The spatially resolved excited state density measurements were combined with previous line integrated measurements in the same discharge geometry to derive spatially resolved, absolute densities of the 1s 5 and 1s 4 argon excited states and gas temperature spatial distributions. Fluorescence lifetime was a strong fi.mction of the rf power, pressure, argon fraction and spatial location. Increasing the power or pressure resulted in a factor of two decrease in the fluorescence lifetime while adding Cl 2 or BCl 3 increased the fluorescence lifetime. Excited state quenching rates are derived from the data. When Cl 2 or BCl 3 was added to the plasma, the maximum argon metastable density depended on the gas and ratio. When chlorine was added to the argon plasma, the spatial density profiles were independent of chlorine fraction. While it is energetically possible for argon excited states to dissociate some of the

A liquid argon scintillation veto for the GERDA experiment

Energy Technology Data Exchange (ETDEWEB)

Wegmann, Anne [Max-Planck-Institut fuer Kernphysik, Saupfercheckweg 1, 69117 Heidelberg (Germany); Collaboration: GERDA-Collaboration

2014-07-01

Gerda is an experiment to search for the neutrinoless double beta decay of {sup 76}Ge. Results of Phase I have been published in summer 2013. Currently Gerda is being upgraded to a second phase. To reach the aspired background index of ≤ 10{sup -3} cts/(keV . kg . yr) for Phase II active background-suppression techniques will be applied, including an active liquid argon veto (LAr veto). It has been demonstrated by the LArGe test facility that the detection of argon scintillation light can be used to effectively suppress background events in the germanium, which simultaneously deposit energy in LAr. This talk focusses on the light instrumentation which is being installed in GERDA. Photomultiplier tubes (PMT) and wavelength-shifting fibers connected to silicon photomultipliers (SiPM) are combined to maximize the photoelectron-yield with respect to various background sources. Monte Carlo simulations have been performed to optimize the design for background suppression and low self-induced background. First results of the prototypes and the progress of installation are reported.

Liquid Argon Barrel Cryostat Arrived

CERN Multimedia

Pailler, P

Last week the first of three cryostats for the ATLAS liquid argon calorimeter arrived at CERN. It had travelled for 46 days over several thousand kilometers from Japan to CERN. During three years it has been fabricated by Kawasaki Heavy Industries Ltd. at Harima, close to Kobe, under contract from Brookhaven National Laboratory (BNL) of the U.S.. This cryostat consists of two concentric cylinders made of aluminium: the outer vacuum vessel with a diameter of 5.5 m and a length of 7 m, and the inner cold vessel which will contain the electromagnetic barrel calorimeter immersed in liquid argon. The total weight will be 270 tons including the detectors and the liquid argon. The cryostat is now located in building 180 where it will be equipped with 64 feed-throughs which serve for the passage of 122,880 electrical lines which will carry the signals of the calorimeter. After integration of the calorimeter, the solenoidal magnet of ATLAS will be integrated in the vacuum vessel. A final cold test of the cryostat inc...

Peach fruit set and buttoning after spring frost

Science.gov (United States)

A spring frost occurred on 29 Mar. 2015 at the USDA-ARS Byron station after three weeks of blooming when most fruitlets were forming. Due to severe fruitlet drop, the overall fruit set on a scale of 0-9 was substantially reduced, from 5.61 averaged in 2014 to 2.61 in 2015. In addition, buttons (abno...

LArGe: active background suppression using argon scintillation for the GERDA 0νββ-experiment

International Nuclear Information System (INIS)

Agostini, M.; Budjas, D.; Schoenert, S.; Barnabe-Heider, M.; Cattadori, C.; Gangapshev, A.; Gusev, K.; Heisel, M.; Smolnikov, A.; Junker, M.; Klimenko, A.; Lubashevskiy, A.; Pelczar, K.; Zuzel, G.

2015-01-01

LArGe is a GERDA low-background test facility to study novel background suppression methods in a low-background environment, for future application in the GERDA experiment. Similar to GERDA, LArGe operates bare germanium detectors submersed into liquid argon (1 m 3 , 1.4tons), which in addition is instrumented with photomultipliers to detect argon scintillation light. The scintillation signals are used in anti-coincidence with the germanium detectors to effectively suppress background events that deposit energy in the liquid argon. The background suppression efficiency was studied in combination with a pulse shape discrimination (PSD) technique using a BEGe detector for various sources, which represent characteristic backgrounds to GERDA. Suppression factors of a few times 10 3 have been achieved. First background data of LArGe with a coaxial HPGe detector (without PSD) yield a background index of (0.12 - 4.6) x 10 -2 cts/(keV kg year) (90 % C.L.), which is at the level of GERDA Phase I. Furthermore, for the first time we monitor the natural 42 Ar abundance (parallel to GERDA), and have indication for the 2νββ-decay in natural germanium. These results show the effectivity of an active liquid argon veto in an ultra-low background environment. As a consequence, the implementation of a liquid argon veto in GERDA Phase II is pursued. (orig.)

LArGe: active background suppression using argon scintillation for the Gerda 0ν β β -experiment

Science.gov (United States)

Agostini, M.; Barnabé-Heider, M.; Budjáš, D.; Cattadori, C.; Gangapshev, A.; Gusev, K.; Heisel, M.; Junker, M.; Klimenko, A.; Lubashevskiy, A.; Pelczar, K.; Schönert, S.; Smolnikov, A.; Zuzel, G.

2015-10-01

LArGe is a Gerda low-background test facility to study novel background suppression methods in a low-background environment, for future application in the Gerda experiment. Similar to Gerda, LArGe operates bare germanium detectors submersed into liquid argon (1 m^3, 1.4 tons), which in addition is instrumented with photomultipliers to detect argon scintillation light. The scintillation signals are used in anti-coincidence with the germanium detectors to effectively suppress background events that deposit energy in the liquid argon. The background suppression efficiency was studied in combination with a pulse shape discrimination (PSD) technique using a BEGe detector for various sources, which represent characteristic backgrounds to Gerda. Suppression factors of a few times 10^3 have been achieved. First background data of LArGe with a coaxial HPGe detector (without PSD) yield a background index of (0.12-4.6)× 10^{-2} cts/(keV kg year) (90 % C.L.), which is at the level of Gerda Phase I. Furthermore, for the first time we monitor the natural ^{42}Ar abundance (parallel to Gerda), and have indication for the 2ν β β -decay in natural germanium. These results show the effectivity of an active liquid argon veto in an ultra-low background environment. As a consequence, the implementation of a liquid argon veto in Gerda Phase II is pursued.

LArGe: active background suppression using argon scintillation for the GERDA 0νββ-experiment

Energy Technology Data Exchange (ETDEWEB)

Agostini, M.; Budjas, D.; Schoenert, S. [Technische Universitaet Muenchen, Munich (Germany); Barnabe-Heider, M. [Technische Universitaet Muenchen, Munich (Germany); Max-Planck-Institut fuer Kernphysik, Heidelberg (Germany); Cattadori, C. [Universita degli Studi di Milano, Milan (Italy); INFN, Milan (Italy); Gangapshev, A. [Max-Planck-Institut fuer Kernphysik, Heidelberg (Germany); Institut for Nuclear Research, Moscow (Russian Federation); Gusev, K. [Technische Universitaet Muenchen, Munich (Germany); Joint Institut for Nuclear Research, Dubna (Russian Federation); National Research Center Kurchatov Institut, Moscow (Russian Federation); Heisel, M.; Smolnikov, A. [Max-Planck-Institut fuer Kernphysik, Heidelberg (Germany); Junker, M. [Laboratori Nazionali del Gran Sasso, Assergi (Italy); Klimenko, A.; Lubashevskiy, A. [Max-Planck-Institut fuer Kernphysik, Heidelberg (Germany); Joint Institut for Nuclear Research, Dubna (Russian Federation); Pelczar, K. [Jagellonian University, Cracow (Poland); Zuzel, G. [Max-Planck-Institut fuer Kernphysik, Heidelberg (Germany); Jagellonian University, Cracow (Poland)

2015-10-15

LArGe is a GERDA low-background test facility to study novel background suppression methods in a low-background environment, for future application in the GERDA experiment. Similar to GERDA, LArGe operates bare germanium detectors submersed into liquid argon (1 m{sup 3}, 1.4tons), which in addition is instrumented with photomultipliers to detect argon scintillation light. The scintillation signals are used in anti-coincidence with the germanium detectors to effectively suppress background events that deposit energy in the liquid argon. The background suppression efficiency was studied in combination with a pulse shape discrimination (PSD) technique using a BEGe detector for various sources, which represent characteristic backgrounds to GERDA. Suppression factors of a few times 10{sup 3} have been achieved. First background data of LArGe with a coaxial HPGe detector (without PSD) yield a background index of (0.12 - 4.6) x 10{sup -2} cts/(keV kg year) (90 % C.L.), which is at the level of GERDA Phase I. Furthermore, for the first time we monitor the natural {sup 42}Ar abundance (parallel to GERDA), and have indication for the 2νββ-decay in natural germanium. These results show the effectivity of an active liquid argon veto in an ultra-low background environment. As a consequence, the implementation of a liquid argon veto in GERDA Phase II is pursued. (orig.)

The effect of watermelon frost on prostaglandin E2 (PGE2 in inflamed pulp tissue (in vitro study

Directory of Open Access Journals (Sweden)

Dennis Dennis

2009-06-01

Full Text Available Background: Pulp inflammation can be marked by the increase of prostaglandin E2(PGE2 level compared to normal pulp. The increase of PGE2 may lead to vasodilatation, increase of vascular permeability, pain and bone resorption. Watermelon frost has been well known in Chinese society for pain relief and inflammation in oral cavity and teeth. Purpose: The aim of this study was to investigate that watermelon frost can be used to decrease the PGE2 level. Method: 27 samples of pulp tissues used in this in-vitro study, were extirpated from the patients’ teeth with symptomatic irreversible pulpitis referred to clinic of Conservative Dentistry, RSPGM Faculty of Dentistry, USU. Trial materials were applied to 27 samples i.e. watermelon frost as a trial material and commercial watermelon frost and eugenol to observe their effect on PGE2. PGE2 level of each material was detected through ELISA method by measuring and comparing the absorbance reading of the wells of the samples against standards with a micro plate reader at W1 = 650 nm and W2 = 490 nm. Result: The result showed the biggest effect was found in the third group (eugenol, mean 4.6933, followed by the first group (watermelon frost as a trial material, mean 18,1578 then the second group (commercial watermelon frost, mean 82,2689. OneWay ANOVA revealed that there were significant differences among all trial materials (p < 0.001 on PGE2 level. Conclusion: This study demonstrated that watermelon frost can be used to decrease the PGE2 level in inflamed pulp tissue and led to the acceptance of traditional medicine and natural products as an alternative form of dental care.

Effect of sodium monofluorophosphate treatment on microstructure and frost salt scaling durability of slag cement paste

International Nuclear Information System (INIS)

Copuroglu, O.; Fraaij, A.L.A.; Bijen, J.M.J.M.

2006-01-01

Sodium-monofluorophosphate (Na-MFP) is currently in use as a surface applied corrosion inhibitor in the concrete industry. Its basic mechanism is to protect the passive layer of the reinforcement steel against disruption due to carbonation. Carbonation is known as the most detrimental environmental effect on blast furnace slag cement (BFSC) concrete with respect to frost salt scaling. In this paper the effect of Na-MFP on the microstructure and frost salt scaling resistance of carbonated BFSC paste is presented. The results of electron microscopy, mercury intrusion porosimetry (MIP) and X-ray diffraction (XRD) are discussed. It is found that the treatment modifies the microstructure and improves the resistance of carbonated BFSC paste against frost salt attack

Shear viscosity of liquid argon and liquid rubidium

International Nuclear Information System (INIS)

Chiakwelu, O.

1978-01-01

A direct evaluation of the shear viscosity coefficient for models of liquid rubidium and liquid argon is presented by neglecting the cross-terms in the autocorrelation function of the transverse component of the momentum stress tensor. The time dependence of the shear viscosity for liquid argon is found to display a long decaying tail in qualitative agreement with a computer calculation of Levesque et al. However, the numerical values of the shear viscosity coefficients are smaller than the experimentally determined values of about 45% for liquid rubidium and 35% for liquid argon

Enhanced Field Emission from Argon Plasma-Treated Ultra-sharp α-Fe2O3Nanoflakes

Directory of Open Access Journals (Sweden)

Zhang JX

2009-01-01

Full Text Available Abstract Hematite nanoflakes have been synthesized by a simple heat oxide method and further treated by Argon plasmas. The effects of Argon plasma on the morphology and crystal structures of nanoflakes were investigated. Significant enhancement of field-induced electron emission from the plasma-treated nanoflakes was observed. The transmission electron microscopy investigation shows that the plasma treatment effectively removes amorphous coating and creates plenty of sub-tips at the surface of the nanoflakes, which are believed to contribute the enhancement of emission. This work suggests that plasma treatment technique could be a direct means to improve field-emission properties of nanostructures.

Future bloom and blossom frost risk for Malus domestica considering climate model and impact model uncertainties.

Science.gov (United States)

Hoffmann, Holger; Rath, Thomas

2013-01-01

The future bloom and risk of blossom frosts for Malus domestica were projected using regional climate realizations and phenological ( = impact) models. As climate impact projections are susceptible to uncertainties of climate and impact models and model concatenation, the significant horizon of the climate impact signal was analyzed by applying 7 impact models, including two new developments, on 13 climate realizations of the IPCC emission scenario A1B. Advancement of phenophases and a decrease in blossom frost risk for Lower Saxony (Germany) for early and late ripeners was determined by six out of seven phenological models. Single model/single grid point time series of bloom showed significant trends by 2021-2050 compared to 1971-2000, whereas the joint signal of all climate and impact models did not stabilize until 2043. Regarding blossom frost risk, joint projection variability exceeded the projected signal. Thus, blossom frost risk cannot be stated to be lower by the end of the 21st century despite a negative trend. As a consequence it is however unlikely to increase. Uncertainty of temperature, blooming date and blossom frost risk projection reached a minimum at 2078-2087. The projected phenophases advanced by 5.5 d K(-1), showing partial compensation of delayed fulfillment of the winter chill requirement and faster completion of the following forcing phase in spring. Finally, phenological model performance was improved by considering the length of day.

Siim Nestor soovitab : Ben Frost ja Alexander Robotnik Eclectical / Siim Nestor

Index Scriptorium Estoniae

Nestor, Siim, 1974-

2007-01-01

Austraalia muusik ja helilooja Ben Frost projektiga "6 guitars" esinemas festivali Eclectica raames 6. sept. Tartu klubis Rock ja Roll ja itaalia diskor Alexander Robotnik 7. sept. klubis Trehv, esinejatest

Performance and emission characteristics of the thermal barrier coated SI engine by adding argon inert gas to intake mixture

Directory of Open Access Journals (Sweden)

T. Karthikeya Sharma

2015-11-01

Full Text Available Dilution of the intake air of the SI engine with the inert gases is one of the emission control techniques like exhaust gas recirculation, water injection into combustion chamber and cyclic variability, without scarifying power output and/or thermal efficiency (TE. This paper investigates the effects of using argon (Ar gas to mitigate the spark ignition engine intake air to enhance the performance and cut down the emissions mainly nitrogen oxides. The input variables of this study include the compression ratio, stroke length, and engine speed and argon concentration. Output parameters like TE, volumetric efficiency, heat release rates, brake power, exhaust gas temperature and emissions of NOx, CO2 and CO were studied in a thermal barrier coated SI engine, under variable argon concentrations. Results of this study showed that the inclusion of Argon to the input air of the thermal barrier coated SI engine has significantly improved the emission characteristics and engine’s performance within the range studied.

Performance and emission characteristics of the thermal barrier coated SI engine by adding argon inert gas to intake mixture.

Science.gov (United States)

Karthikeya Sharma, T

2015-11-01

Dilution of the intake air of the SI engine with the inert gases is one of the emission control techniques like exhaust gas recirculation, water injection into combustion chamber and cyclic variability, without scarifying power output and/or thermal efficiency (TE). This paper investigates the effects of using argon (Ar) gas to mitigate the spark ignition engine intake air to enhance the performance and cut down the emissions mainly nitrogen oxides. The input variables of this study include the compression ratio, stroke length, and engine speed and argon concentration. Output parameters like TE, volumetric efficiency, heat release rates, brake power, exhaust gas temperature and emissions of NOx, CO2 and CO were studied in a thermal barrier coated SI engine, under variable argon concentrations. Results of this study showed that the inclusion of Argon to the input air of the thermal barrier coated SI engine has significantly improved the emission characteristics and engine's performance within the range studied.

Performance investigation of a novel frost-free air-source heat pump water heater combined with energy storage and dehumidification

International Nuclear Information System (INIS)

Wang, Fenghao; Wang, Zhihua; Zheng, Yuxin; Lin, Zhang; Hao, Pengfei; Huan, Chao; Wang, Tian

2015-01-01

Highlights: • Experiments are carried out to investigate a novel frost-free ASHPWH system. • Dynamic characteristics of the system are studied at different ambient conditions. • Test results confirm the expected potential to control the frost-free process. • The COP increased 17.9% and 3.4% respectively in comparison with RCD at −3 °C and 3 °C. - Abstract: Air-source heat pump (ASHP) often operates with substantial frost formation on the outdoor heat exchanger at low ambient temperature in winter, it insulates the finned surface and also reduces heat transfer rate, leading to performance degradation or even shutdown of ASHP systems. Although several defrosting methods have been reported, the frosting and defrosting processes reduced energy efficiency and resulted in, in some cases, heat pump breakdown. To solve this problem, a novel frost-free air-source heat pump water heater (ASHPWH) system has been developed, which coupled with an extra heat exchanger coated by a solid desiccant (EHECSD) with an energy storage device (ESD). Based on the previous studies, a further analysis and comprehensive research on the novel frost-free ASHPWH system is presented in this paper. The dynamic characteristics of the novel system are investigated experimentally in different ambient conditions. An experimental setup and experimental procedures are described in detail. Thereafter, the dehumidification efficiency and regeneration efficiency of EHECSD, suction and discharge pressures of the compressor, the temperature of PCM are evaluated during the heating and regeneration modes respectively. Results indicate that the system can keep the evaporator frost-free for 32, 34, 36 min during heating mode at the ambient temperatures of −3 °C, 0 °C and 3 °C and 85% RH. Compared with the reverse-cycle defrosting (RCD), COP of the frost-free ASHPWH are 17.9% and 3.4% higher at the ambient temperature of −3 °C and 3 °C respectively. With this innovative technology, it has

Trapping cold ground state argon atoms.

Science.gov (United States)

Edmunds, P D; Barker, P F

2014-10-31

We trap cold, ground state argon atoms in a deep optical dipole trap produced by a buildup cavity. The atoms, which are a general source for the sympathetic cooling of molecules, are loaded in the trap by quenching them from a cloud of laser-cooled metastable argon atoms. Although the ground state atoms cannot be directly probed, we detect them by observing the collisional loss of cotrapped metastable argon atoms and determine an elastic cross section. Using a type of parametric loss spectroscopy we also determine the polarizability of the metastable 4s[3/2](2) state to be (7.3±1.1)×10(-39)  C m(2)/V. Finally, Penning and associative losses of metastable atoms in the absence of light assisted collisions, are determined to be (3.3±0.8)×10(-10)  cm(3) s(-1).

Observations of acoustic-wave-induced superluminescence in an argon plasma

International Nuclear Information System (INIS)

Aramyan, A.R.

2003-01-01

It is shown that in an argon discharge plasma it is possible to obtain overpopulation of certain electronic levels of atomic argon under the influence of acoustic waves. When the specified threshold is exceeded, then a superluminescence (in the form of light flashes) from the overpopulated electronic levels of atomic argon is observed

Modeling of Liquid Steel/Slag/Argon Gas Multiphase Flow During Tundish Open Eye Formation in a Two-Strand Tundish

Science.gov (United States)

Chatterjee, Saikat; Li, Donghui; Chattopadhyay, Kinnor

2018-04-01

Multiphase flows are frequently encountered in metallurgical operations. One of the most effective ways to understand these processes is by flow modeling. The process of tundish open eye (TOE) formation involves three-phase interaction between liquid steel, slag, and argon gas. The two-phase interaction involving argon gas bubbles and liquid steel can be modeled relatively easily using the discrete phase modeling technique. However, the effect of an upper slag layer cannot be captured using this approach. The presence of an upper buoyant phase can have a major effect on the behavior of TOEs. Hence, a multiphase model, including three phases, viz. liquid steel, slag, and argon gas, in a two-strand slab caster tundish, was developed to study the formation and evolution of TOEs. The volume of fluid model was used to track the interphase between liquid steel and slag phases, while the discrete phase model was used to trace the movement of the argon gas bubbles in liquid steel. The variation in the TOE areas with different amounts of aspirated argon gas was examined in the presence of an overlying slag phase. The mathematical model predictions were compared against steel plant measurements.

Fast sampling calorimetry with solid argon ionization chambers

International Nuclear Information System (INIS)

Clark, E.; Linn, S.; Piekarz, H.; Wahl, H.; Womersley, J.; Hansen, S.; Hurh, P.; Rivetta, C.; Sanders, R.; Schmitt, R.; Stanek, R.; Stefanik, A.

1992-01-01

A proposal for the fast sampling calorimetry with solid argon as active medium and the preliminary results from the solid argon test cell are presented. The proposed test calorimeter module structure, the signal routing and the mechanical and cryogenic arrangements are also discussed

Cleaning of diffusion bonding surface by argon ion bombardment treatment

International Nuclear Information System (INIS)

Wang, Airu; Ohashi, Osamu; Yamaguchi, Norio; Aoki, Masanori; Higashi, Yasuo; Hitomi, Nobuteru

2003-01-01

The specimens of oxygen-free high conductivity copper, SUS304L stainless steel and pure iron were treated by argon ion bombardment and then were bonded by diffusion bonding method. The effects of argon ion bombardment treatment on faying surface morphology, tensile strength of bonding joints and inclusions at the fracture surface were investigated. The results showed that argon ion bombardment treatment was effective to remove the oxide film and contamination at the faying surface and improve the quality of joints. The tensile strength of the bonded joints was improved, and minimum bonding temperature to make the metallic bonding at the interface was lowered by argon ion bombardment treatment. At the joints with argon ion bombardment treatment, ductile fractured surface was seen and the amount of inclusions was obviously decreased

Recent changes in frost days events characteristics in Uruguay-Southeastern South America.

Science.gov (United States)

Renom, Madeleine; De Mello, Santiago

2015-04-01

There are few studies about extreme temperature events in Southeastern South America as is it mentioned in the SREX report (2009), although these events generate human health impacts and big economical looses. Southeastern South America is one of the major agricultural production regions worldwide. Particularly in Uruguay, agricultural production represents a high percentage of the GDP and, in the last 15 years there has been a significant increase in the area used for that economic activity. Although frost is not always is considered as an extreme event it causes, in the case of Uruguay, an impact on society, energy consumption and agricultural losses. Previous studies have shown a negative trend in the occurrence of cold nights (TN10) during winter (June-July-August) and autumn (March-April-May) in Uruguay. This work try to determine if these trends affects the occurrences and characteristics of frost days (Tmin< 0°C). Based on a high-quality daily minimum temperature for 11 meteorological stations that cover the period 1950-2009, we analyzed different features of frost days. Long term trends do not present a clear spatial behaviour suggesting that there is a not clear relationship between the percentile based index (TN10) and a fixed index (FD). At monthly scale, May and September show a negative trend, although these months present a low number of cases that difficult the statistical treatment. It is noticeable that from a decadal point of view the last decade (2000-2009) was the decade with fewer occurrences comparing with the rest, while the 90's is the decade that presents more cases. We also analyzed changes in frost period (FP) which commonly extends from May to September. In general all the stations present a decrease in the FP in accordance with the negative trend detected at monthly scale, suggesting a warming in autumn and spring time. Although we detected different behaviour in two stations, one located inner land and the other located on the

Simulating the Probability of Grain Sorghum Maturity before the First Frost in Northeastern Colorado

Directory of Open Access Journals (Sweden)

Gregory S. McMaster

2016-09-01

Full Text Available Expanding grain sorghum [Sorghum bicolor (L. Moench] production northward from southeastern Colorado is thought to be limited by shorter growing seasons due to lower temperatures and earlier frost dates. This study used a simulation model for predicting crop phenology (PhenologyMMS to estimate the probability of reaching physiological maturity before the first fall frost for a variety of agronomic practices in northeastern Colorado. Physiological maturity for seven planting dates (1 May to 12 June, four seedbed moisture conditions affecting seedling emergence (from Optimum to Planted in Dust, and three maturity classes (Early, Medium, and Late were simulated using historical weather data from nine locations for both irrigated and dryland phenological parameters. The probability of reaching maturity before the first frost was slightly higher under dryland conditions, decreased as latitude, longitude, and elevation increased, planting date was delayed, and for later maturity classes. The results provide producers with estimates of the reliability of growing grain sorghum in northeastern Colorado.

The effects of frost thickness on the heat transfer of finned tube heat exchanger subject to the combined influence of fan types

Energy Technology Data Exchange (ETDEWEB)

Huang, Jeng-Min; Hsieh, Wen-Chien; Ke, Xin-Ji [Department of Refrigeration, Air Conditioning National Chin-Yi University of Technology, Taichung County, Taiping City 411 (China); Wang, Chi-Chuan [Energy and Environment Research Laboratories, Industrial Technology Research Institute, Hsinchu 310 (China)

2008-05-15

This study conducts a numerical study concerning the effect of frost thickness on the heat transfer performance of a four rows plate finned tube heat exchanger. Calculations are made under constant air volume and variable air volume conditions. It is found that the initial surge of heat transfer rate in the frosted finned tube heat exchanger is mainly associated with the critical radius effect rather than the surface roughness. The frost thermal conductivity plays an important role in the surge phenomenon. There is hardly any initial surge when frost thermal conductivity is below 0.1 W m{sup -1} K{sup -1}. It is also recommended that a refrigerator should defrost when half of a single flow channel area is blocked by frost. The calculations also reveal that a centrifugal fan is recommended with a small fin-pitch heat exchanger. However, if a long term operation at a thick frost situation is unavoidable, an axial fan should be selected. There is no great difference between selection of an axial fan or centrifugal fan for a larger fin pitch heat exchanger. (author)

Changes of Frost Damage and Treeline Advance for Swiss Stone Pine in the Calimani Mts. (Eastern Carpathians, Romania

Directory of Open Access Journals (Sweden)

KERN, Zoltán

2008-01-01

Full Text Available Checking the tree-ring structure of 39 living and 9 crossdated dead samples of Swissstone pine (Pinus cembra L. collected from the upper timberline of the CalimaniMts. we haveidentified 59 frost rings over the past 250 years. We found concentrated occurrence of frost events inthree decades: in the 1790s, 1810s and 1910s. No frost ring was observed in two bidecadal periods:1750-1770 and 1850-1870. Out of the analysed interval 1963-2004 is the longest period without frostring occurrence. After 1920 both frequency and severity of frost events seem to decrease compared tothe prior 170 years. We determined the altitude of highest growing stone pine individuals in theBradului Ciont–Pietrosu region in June, 2006. Individuals were sorted into tree-form or bush-likemorphological groups. Mean elevation data of the groups were corrected by an estimated constant biasof GPS measurements (-30 m. Comparing the corrected values to early 20th century inventory data65 m and 95 m upward migration was determined for treeline and boundary of bush-like occurence,respectively. The parallel results suggest that the 20th century advance of the upper forest limit wasdue to the decrease of frost stress at the zone of timberline.

Cryoprotectants are metabolic fuels during long term frost exposure in the earthworm Dendrobaena octaedra.

DEFF Research Database (Denmark)

C. Jørgensen, Sofia; Overgaard, Johannes; Holmstrup, Martin

2008-01-01

Ectothermic animals that live in the subarctic and temperate regions must have strategies to deal with periods of frost during winter. The earthworm Dendrobaena octaedra is a freeze tolerant species that accumulates large concentrations of the cryoprotectant glucose upon ice formation in the extr......Ectothermic animals that live in the subarctic and temperate regions must have strategies to deal with periods of frost during winter. The earthworm Dendrobaena octaedra is a freeze tolerant species that accumulates large concentrations of the cryoprotectant glucose upon ice formation...

Frost flowers and sea-salt aerosols over seasonal sea-ice areas in northwestern Greenland during winter–spring

Directory of Open Access Journals (Sweden)

K. Hara

2017-07-01

Full Text Available Sea salts and halogens in aerosols, frost flowers, and brine play an important role in atmospheric chemistry in polar regions. Simultaneous sampling and observations of frost flowers, brine, and aerosol particles were conducted around Siorapaluk in northwestern Greenland during December 2013 to March 2014. Results show that water-soluble frost flower and brine components are sea-salt components (e.g., Na+, Cl−, Mg2+, K+, Ca2+, Br−, and iodine. Concentration factors of sea-salt components of frost flowers and brine relative to seawater were 1.14–3.67. Sea-salt enrichment of Mg2+, K+, Ca2+, and halogens (Cl−, Br−, and iodine in frost flowers is associated with sea-salt fractionation by precipitation of mirabilite and hydrohalite. High aerosol number concentrations correspond to the occurrence of higher abundance of sea-salt particles in both coarse and fine modes, and blowing snow and strong winds. Aerosol number concentrations, particularly in coarse mode, are increased considerably by release from the sea-ice surface under strong wind conditions. Sulfate depletion by sea-salt fractionation was found to be limited in sea-salt aerosols because of the presence of non-sea-salt (NSS SO42−. However, coarse and fine sea-salt particles were found to be rich in Mg. Strong Mg enrichment might be more likely to proceed in fine sea-salt particles. Magnesium-rich sea-salt particles might be released from the surface of snow and slush layer (brine on sea ice and frost flowers. Mirabilite-like and ikaite-like particles were identified only in aerosol samples collected near new sea-ice areas. From the field evidence and results from earlier studies, we propose and describe sea-salt cycles in seasonal sea-ice areas.

Frost flowers and sea-salt aerosols over seasonal sea-ice areas in northwestern Greenland during winter-spring

Science.gov (United States)

Hara, Keiichiro; Matoba, Sumito; Hirabayashi, Motohiro; Yamasaki, Tetsuhide

2017-07-01

Sea salts and halogens in aerosols, frost flowers, and brine play an important role in atmospheric chemistry in polar regions. Simultaneous sampling and observations of frost flowers, brine, and aerosol particles were conducted around Siorapaluk in northwestern Greenland during December 2013 to March 2014. Results show that water-soluble frost flower and brine components are sea-salt components (e.g., Na+, Cl-, Mg2+, K+, Ca2+, Br-, and iodine). Concentration factors of sea-salt components of frost flowers and brine relative to seawater were 1.14-3.67. Sea-salt enrichment of Mg2+, K+, Ca2+, and halogens (Cl-, Br-, and iodine) in frost flowers is associated with sea-salt fractionation by precipitation of mirabilite and hydrohalite. High aerosol number concentrations correspond to the occurrence of higher abundance of sea-salt particles in both coarse and fine modes, and blowing snow and strong winds. Aerosol number concentrations, particularly in coarse mode, are increased considerably by release from the sea-ice surface under strong wind conditions. Sulfate depletion by sea-salt fractionation was found to be limited in sea-salt aerosols because of the presence of non-sea-salt (NSS) SO42-. However, coarse and fine sea-salt particles were found to be rich in Mg. Strong Mg enrichment might be more likely to proceed in fine sea-salt particles. Magnesium-rich sea-salt particles might be released from the surface of snow and slush layer (brine) on sea ice and frost flowers. Mirabilite-like and ikaite-like particles were identified only in aerosol samples collected near new sea-ice areas. From the field evidence and results from earlier studies, we propose and describe sea-salt cycles in seasonal sea-ice areas.

ATLAS endcap liquid argon calorimeters. Description and construction of the cryostats

Energy Technology Data Exchange (ETDEWEB)

Mace, Guy; Prat, Serge; Veillet, Jean-Jacques [Laboratoire de l' Accelerateur Lineaire IN2P3-CNRS et Universite de Paris-Sud 11, BP 34, F-91898 Orsay Cedex (France)

2006-05-15

All forward calorimeters of the ATLAS detector use the same detection technique, energy loss in passive plates, followed by ionisation and charge detection in liquid argon. They are therefore all grouped in the same vessel which must basically support and keep in place the heavy plates and the detection electrodes and maintain liquid argon at cold and stable temperature. Taking into account all the constraints as detailed below, and the overall detector size, 5 meter diameter by 3 meter length this was quite a challenge. The design, construction and tests of these two cryostats, up to their delivery at CERN, are described in this document. These two cryostats are a joint 'in kind' contribution to the Atlas experiment of LAL (Orsay), Max Planck Institute (Muenchen) and Wuppertal University (Wuppertal) and have been designed and built under the responsibility of LAL (Orsay) with contributions of the technical groups of the above institutions and of ATLAS-CERN. (authors)

ATLAS endcap liquid argon calorimeters. Description and construction of the cryostats

International Nuclear Information System (INIS)

Mace, Guy; Prat, Serge; Veillet, Jean-Jacques

2006-05-01

All forward calorimeters of the ATLAS detector use the same detection technique, energy loss in passive plates, followed by ionisation and charge detection in liquid argon. They are therefore all grouped in the same vessel which must basically support and keep in place the heavy plates and the detection electrodes and maintain liquid argon at cold and stable temperature. Taking into account all the constraints as detailed below, and the overall detector size, 5 meter diameter by 3 meter length this was quite a challenge. The design, construction and tests of these two cryostats, up to their delivery at CERN, are described in this document. These two cryostats are a joint 'in kind' contribution to the Atlas experiment of LAL (Orsay), Max Planck Institute (Muenchen) and Wuppertal University (Wuppertal) and have been designed and built under the responsibility of LAL (Orsay) with contributions of the technical groups of the above institutions and of ATLAS-CERN. (authors)

Argon spill in the hall of the ATLAS experiment

CERN Document Server

Peón-Hernández, G

1998-01-01

A hazard analysis is in progress to determine the operation mode of the ventilation system in the ATLAS hall in case of an Argon spill. Two risk scenarios have been investigated so far. In the first, the behaviour of an Argon gas pool is calculated for different ventilation strategies. In the second, the behaviour of Argon gas leaking from the bottom part of the detector is studied for different flows. The description of the study, results and conclusions are presented.

Comparison between argon/methane and argon/ethane gas mixtures in cylindrical drift chambers operating in a high transverse magnetic field

International Nuclear Information System (INIS)

Binder, U.; Boer, W. de; Grindhammer, G.; Kotthaus, R.; Lierl, H.; Sack, B.

1983-03-01

We compare the behaviour of two commonly used gas mixtures argon/methane (90:10) and argon/ethane (50:50) in large cylindrical drift chambers operating in a transverse magnetic field of 1.3 T. The cooler gas argon/ethane was found to exhibit considerably smaller deflection angles, which in our case leads to an improved performance of the chambers. The deflection angles have been determined from a comparison of the experimental non-linear space time relation with the one calculated from a computer simulation of the drift process. For the simulation we use a simple model with only two free parameters. These two parameters are sufficient to obtain an accurate parametrization of the non-linear space time relation. (orig.)

Comparison between argon/methane and argon/ethane gas mixtures in cylindrical drift chambers operating in a high transverse magnetic field

International Nuclear Information System (INIS)

Binder, U.; De Boer, W.; Grindhammer, G.; Kotthaus, R.; Lierl, H.; Sack, B.

1983-01-01

We compare the behaviour of two commonly used gas mixture argon/methane (90:10) and argon/ethane (50:50) in large cylindrical drift chambers operating in a transverse magnetic field of 1.3 T. The cooler gas argon/ethane was found to exhibit considerably smaller deflection angles, which in our case leads to an improved performance of the chambers. The deflection angles have been determined from a comparison of the experimental non-linear space-time relation with the one calculated from a computer simulation of the drift process. For the simulation we use a simple model with only two free parameters. These two parameters are sufficient to obtain an accurate parametrization of the non-linear space-time relation. (orig.)

Automated cycled sprinkler irrigation for spring frost protection of cranberries

Science.gov (United States)

Sprinkler irrigation is essential for preventing spring frost bud damage in cranberry (Vaccinium macrocarpon Ait). Risk-averse growers have been reluctant to adopt the intermittent cycling of irrigation pumps as a standard management practice. In the spring of 2013 and 2014, an experiment was conduc...

Frost flowers on young Arctic sea ice: The climatic, chemical, and microbial significance of an emerging ice type

DEFF Research Database (Denmark)

Barber, D. G.; Ehn, J. K.; Pucko, M.

2014-01-01

flowers primarily originated from the surface brine skim. Ikaite crystals were observed to form within an hour in both frost flowers and the thin pond ice. Average ikaite concentrations were 1013 mu molkg(-1) in frost flowers and 1061 mu molkg(-1) in the surface slush layer. Chamber flux measurements...

Interactions between near-ground temperature and radiation, silvicultural treatments and frost damage to Norway spruce seedlings

OpenAIRE

Langvall, Ola

2000-01-01

Several different silvicultural treatments were studied in two experiments. In the first, mechanical scarification, slash removal, vegetation control, clear-cut age and seedling types were investigated with respect to frost injury to Norway spruce (Picea abies (L.) Karst.) seedlings. Frost damage was also related to near-ground minimum temperature. In the other experiment, the effects of Scots pine (Pinus sylvestris (L.)) shelterwood density gradients, ranging from dense, uncut forest to comp...

Cryodeposition of nitrogen gas on a surface cooled by helium II

International Nuclear Information System (INIS)

Dhuley, R. C.; Bosque, E. S.; Van Sciver, S. W.

2014-01-01

Catastrophic loss of beam tube vacuum in a superconducting particle accelerator can be simulated by sudden venting of a long high vacuum channel cooled on its outer surface by He II. The rapid rush of atmospheric air in such an event shows an interesting propagation effect, which is much slower than the shock wave that occurs with vacuum loss at ambient conditions. This is due to flash frosting/deposition of air on the cold walls of the channel. Hence to characterize the propagation as well as the associated heat transfer, it is first necessary to understand the deposition process. Here we attempt to model the growth of nitrogen frost layer on a cold plate in order to estimate its thickness with time. The deposition process can be divided into two regimes- free molecular and continuum. It is shown that in free molecular regime, the frost growth can be modeled reasonably well using cryopump theory and general heat transfer relations. The continuum regime is more complex to model, given the higher rate of gas incident on cryosurface causing a large heat load on helium bath and changing cryosurface temperature. Results from the continuum regime are discussed in the context of recent experiments performed in our laboratory

Cryodeposition of nitrogen gas on a surface cooled by helium II

Energy Technology Data Exchange (ETDEWEB)

Dhuley, R. C.; Bosque, E. S.; Van Sciver, S. W. [Cryogenics Group, National High Magnetic Field Laboratory, Tallahassee, FL 32310 USA and Mechanical Engineering Department, FAMU-FSU College of Engineering, Tallahassee, FL 32310 (United States)

2014-01-29

Catastrophic loss of beam tube vacuum in a superconducting particle accelerator can be simulated by sudden venting of a long high vacuum channel cooled on its outer surface by He II. The rapid rush of atmospheric air in such an event shows an interesting propagation effect, which is much slower than the shock wave that occurs with vacuum loss at ambient conditions. This is due to flash frosting/deposition of air on the cold walls of the channel. Hence to characterize the propagation as well as the associated heat transfer, it is first necessary to understand the deposition process. Here we attempt to model the growth of nitrogen frost layer on a cold plate in order to estimate its thickness with time. The deposition process can be divided into two regimes- free molecular and continuum. It is shown that in free molecular regime, the frost growth can be modeled reasonably well using cryopump theory and general heat transfer relations. The continuum regime is more complex to model, given the higher rate of gas incident on cryosurface causing a large heat load on helium bath and changing cryosurface temperature. Results from the continuum regime are discussed in the context of recent experiments performed in our laboratory.

Stopping Power of Solid Argon for Helium Ions

DEFF Research Database (Denmark)

Besenbacher, F.; Bøttiger, Jørgen; Grauersen, O.

1981-01-01

By means of the Rutherford-backscattering method, the stopping cross section of solid argon has been measured for 0.5–3 MeV helium ions to an accuracy of not, vert, similar3%. The results agree within the experimental accuracies with our earlier measurements for gaseous argon over the energy region...

Evaluations on power ramp data of PWR fuels by FROST and THERMOST codes

International Nuclear Information System (INIS)

Murai, K.; Ogawa, S.; Nuno, H.; Kondo, Y.

1987-01-01

An evaluation is presented of power ramp data of Mitsubishi's PWR fuel rods tested in R-2, Studsvik, which was analysed by FROST and THERMOST codes. The analyses give good predictions for measured diameter changes and on-power rod elongations. The work indicates that FROST is capable of analysing both radial and axial pellet-cladding mechanism interaction (PCMI) appropriately, and that predicted states of PCMI (i.e. stress and strain which cannot be measured directly) are considered to be reliable. The ramp data used in the present analyses were obtained in two joint programmes with five Japanese PWR utilities (KEPCO, KYEPCO, SEPCO, HEPCO, and JAPCO). (UK)

Delineation of frost characteristics on cold walls by using a new formula for psychrometrics demarcation boundary

International Nuclear Information System (INIS)

Ali, Ahmed Hamza H.

2009-01-01

In this study, a direct formula that predicts either the frost formation on cold walls is correspondence to psychrometric-subsaturated or supersaturated regions is presented. The developed formula uses the data of the entering air dry-bulb temperature and absolute humidity, and the absolute humidity of the air at saturation corresponding to the coil surface temperature. Cases studies of demarcation criteria for frost formation on evaporator coil using experimental measured data, and on walls of cold storage freezer using measured data from literature are used to validate the formula and it is found that results are completely matches to the graphic plot of the data on the psychrometric chart. In case of cold storage freezers, the result clearly shows that a greater demarcation criteria value indicates frost formation under sever condition that is characterized as snow-like with low density and thermal conductivity.

Purafil-filtration prevents the development of ozone-induced frost injury: A potential role for nitric oxide

Science.gov (United States)

Neighbour, E. A.; Pearson, M.; Mehlhorn, H.

The relationship between exposure to ozone in the summer and the subsequent development of frost hardiness in the autumn was evaluated in recent experiments with red spruce ( Picea rubens Sarg. Syn. P. rubra). When O 3 was added to air filtered only through charcoal (contaminated with nitric oxide (NO)), frost sensitivity in late autumn was increased as measured by conductivity from electrocyte leakage. However, when O 3 was added to air filtered through charcoal and Purafil (no NO), no enhancement of frost sensitivity was found. A possible explanation of this difference, involving the chain-propagating property of NO in the O 3-initiated oxidation of unsaturated hydrocarbons (HCs), is proposed and discussed. N 2O 5, which was found to be generated at approximately 0.02 moles per mole of O 3 in the first year's experiment, only marginally modified O 3 toxicity.

Pressure regulation in the dry-boxes. Argon purification

International Nuclear Information System (INIS)

Pascard, R.; Fabre, R.

1958-01-01

Each dry-box is equipped with an autonomous installation for circulation and purification of argon and for pressure regulation. This installation consists essentially of a ballast tank, a compressor and two valves electromagnetically controlled by a contact manometer. The compressor and the valves are enclosed in the tank to form a system as compact as possible. The argon is purified by passing it over a furnace filled with titanium-zirconium turnings brought to about 800 deg. C, branching off the main system. With this set-up as well as the automatic maintenance of a constant depression in the box, a quality of argon is obtained whose oxygen contact is undetectable by the manganous hydroxide method. (author) [fr

Polydiagnostic calibration performed on a low pressure surface wave sustained argon plasma

International Nuclear Information System (INIS)

Vries, N de; Iordanova, E I; Van Veldhuizen, E M; Mullen, J J A M van der; Palomares, J M

2008-01-01

The electron density and electron temperature of a low pressure surface wave sustained argon plasma have been determined using passive and active (laser) spectroscopic methods simultaneously. In this way the validity of the various techniques is established while the plasma properties are determined more precisely. The electron density, n e , is determined with Thomson scattering (TS), absolute continuum measurements, Stark broadening and an extrapolation of the atomic state distribution function (ASDF). The electron temperature, T e , is obtained using TS and absolute line intensity (ALI) measurements combined with a collisional-radiative (CR) model for argon. At an argon pressure of 15 mbar, the n e values obtained with TS and Stark broadening agree with each other within the error bars and are equal to (4 ± 0.5) x 10 19 m -3 , whereas the n e value (2 ± 0.5) x 10 19 m -3 obtained from the continuum is about 30% lower. This suggests that the used formula and cross-section values for the continuum method have to be reconsidered. The electron density determined by means of extrapolation of the ASDF to the continuum is too high (∼10 20 m -3 ). This is most probably related to the fact that the plasma is strongly ionizing so that the extrapolation method is not justified. At 15 mbar, the T e values obtained with TS are equal to 13 400 ± 1100 K while the ALI/CR-model yields an electron temperature that is about 10% lower. It can be concluded that the passive results are in good or fair agreement with the active results. Therefore, the calibrated passive methods can be applied to other plasmas in a similar regime for which active diagnostic techniques cannot be used.

Polydiagnostic calibration performed on a low pressure surface wave sustained argon plasma

Energy Technology Data Exchange (ETDEWEB)

Vries, N de; Iordanova, E I; Van Veldhuizen, E M; Mullen, J J A M van der [Department of Applied Physics, Eindhoven University of Technology, PO Box 513, 5600 MB Eindhoven (Netherlands); Palomares, J M [Departamento de Fisica, Universidad de Cordoba, Campus de Rabanales, ed. C-2, 14071 Cordoba (Spain)], E-mail: j.j.a.m.v.d.Mullen@tue.nl

2008-10-21

The electron density and electron temperature of a low pressure surface wave sustained argon plasma have been determined using passive and active (laser) spectroscopic methods simultaneously. In this way the validity of the various techniques is established while the plasma properties are determined more precisely. The electron density, n{sub e}, is determined with Thomson scattering (TS), absolute continuum measurements, Stark broadening and an extrapolation of the atomic state distribution function (ASDF). The electron temperature, T{sub e}, is obtained using TS and absolute line intensity (ALI) measurements combined with a collisional-radiative (CR) model for argon. At an argon pressure of 15 mbar, the n{sub e} values obtained with TS and Stark broadening agree with each other within the error bars and are equal to (4 {+-} 0.5) x 10{sup 19} m{sup -3}, whereas the n{sub e} value (2 {+-} 0.5) x 10{sup 19} m{sup -3} obtained from the continuum is about 30% lower. This suggests that the used formula and cross-section values for the continuum method have to be reconsidered. The electron density determined by means of extrapolation of the ASDF to the continuum is too high ({approx}10{sup 20} m{sup -3}). This is most probably related to the fact that the plasma is strongly ionizing so that the extrapolation method is not justified. At 15 mbar, the T{sub e} values obtained with TS are equal to 13 400 {+-} 1100 K while the ALI/CR-model yields an electron temperature that is about 10% lower. It can be concluded that the passive results are in good or fair agreement with the active results. Therefore, the calibrated passive methods can be applied to other plasmas in a similar regime for which active diagnostic techniques cannot be used.

The optimization of a tubular condensation cryopump for pressures below 10/sup -13/ Torr (for intersecting storage rings for protons)

CERN Document Server

Benvenuti, C

1974-01-01

A cryopump design of tubular geometry is presented, which incorporates in its vacuum system only a very small fraction of ambient temperature walls. Furthermore, the total amount of the 300K radiation reaching the cold baffles is reduced by about two orders of magnitude. This has the double advantage that the baffles can be cooled at lower temperatures and can be allowed to be more 'transparent' to radiation and hence to molecules. The new model has been entirely optimised both for molecular and radiation transmission by a Monte Carlo method. It is designed to have a pumping speed of 3000 ls/sup -1/ for H/sub 2/ at the two entrances, an axial conductance providing a pressure drop across the pump of a factor of ten and a limit pressure in the 10/sup -14/ Torr range. (6 refs).

Modeling of inhomogeneous mixing of plasma species in argon-steam arc discharge

Science.gov (United States)

Jeništa, J.; Takana, H.; Uehara, S.; Nishiyama, H.; Bartlová, M.; Aubrecht, V.; Murphy, A. B.

2018-01-01

This paper presents numerical simulation of mixing of argon- and water-plasma species in an argon-steam arc discharge generated in a thermal plasma generator with the combined stabilization of arc by axial gas flow (argon) and water vortex. The diffusion of plasma species itself is described by the combined diffusion coefficients method in which the coefficients describe the diffusion of argon ‘gas,’ with respect to water vapor ‘gas.’ Diffusion processes due to the gradients of mass density, temperature, pressure, and an electric field have been considered in the model. Calculations for currents 150-400 A with 15-22.5 standard liters per minute (slm) of argon reveal inhomogeneous mixing of argon and oxygen-hydrogen species with the argon species prevailing near the arc axis. All the combined diffusion coefficients exhibit highly nonlinear distribution of their values within the discharge, depending on the temperature, pressure, and argon mass fraction of the plasma. The argon diffusion mass flux is driven mainly by the concentration and temperature space gradients. Diffusions due to pressure gradients and due to the electric field are of about 1 order lower. Comparison with our former calculations based on the homogeneous mixing assumption shows differences in temperature, enthalpy, radiation losses, arc efficiency, and velocity at 400 A. Comparison with available experiments exhibits very good qualitative and quantitative agreement for the radial temperature and velocity profiles 2 mm downstream of the exit nozzle.

Impact of Argon gas on optical and electrical properties of Carbon thin films

Energy Technology Data Exchange (ETDEWEB)

Usman, Arslan, E-mail: arslan.usman@gmail.com [Department of Physics, COMSATS Institute of Information Technology, Lahore (Pakistan); Rafique, M.S. [Department of Physics, University of Engineering & Technology, Lahore 54890 (Pakistan); Shaukat, S.F. [Department of Physics, COMSATS Institute of Information Technology, Lahore (Pakistan); Siraj, Khurram [Department of Physics, University of Engineering & Technology, Lahore 54890 (Pakistan); Ashfaq, Afshan [Institute of Nuclear Medicine and Oncology Lahore (INMOL), 54000 Pakistan (Pakistan); Anjum, Safia [Department of Physics, Lahore College for Women University (Pakistan); Imran, Muhammad; Sattar, Abdul [Department of Physics, COMSATS Institute of Information Technology, Lahore (Pakistan)

2016-12-15

Nanostructured thin films of carbon were synthesized and investigated for their electrical, optical, structural and surface properties. Pulsed Laser Deposition (PLD) technique was used for the preparation of these films under Argon gas environment. A KrF Laser (λ=248 nm) was used as source of ablation and plasma formation. It was observed that the carbon ions and the background gas environment has deep impact on the morphology as well as on the microstructure of the films. Time of Flight (TOF) method was used to determine the energies of the ablated carbon ions. The morphology of film surfaces deposited at various argon pressure was analysed using an atomic force microscope. The Raman spectroscopic measurement reveal that there is shift in phase from sp{sup 3} to sp{sup 2} and a decrease in FWHM of G band, which is a clear indication of enhanced graphitic clusters. The electrical resistivity was also reduced from 85.3×10{sup −1} to 2.57×10{sup −1} Ω-cm. There is an exponential decrease in band gap E{sub g} of the deposited films from 1.99 to 1.37 eV as a function of argon gas pressure.

ArgonCube: a novel, fully-modular approach for the realization of large-mass liquid argon TPC neutrino detectors

CERN Document Server

Amsler, C; Asaadi, J; Auger, M; Barbato, F; Bay, F; Bishai, M; Bleiner, D; Borgschulte, A; Bremer, J; Cavus, E; Chen, H; De Geronimo, G; Ereditato, A; Fleming, B; Goldi, D; Hanni, R; Kose, U; Kreslo, I; La Mattina, F; Lanni, F; Lissauer, D; Luthi, M; Lutz, P; Marchionni, A; Mladenov, D; Nessi, M; Noto, F; Palamara, O; Raaf, J L; Radeka, V; Rudolph Von Rohr, Ch; Smargianaki, D; Soderberg, M; Strauss, Th; Weber, M; Yu, B; Zeller, G P; Zeyrek, M; CERN. Geneva. SPS and PS Experiments Committee; SPSC

2015-01-01

The Liquid Argon Time Projection Chamber is a prime candidate detector for future neutrino oscillation physics experiments, underground neutrino observatories and proton decay searches. A large international project based on this technology is currently being considered at the future LBNF facility in the United States on the very large mass scale of 40 kton. In this document, following the long standing R&D work conducted over the last years in several laboratories in Europe and in the United States, we intend to propose a novel Liquid Argon TPC approach based on a fully-modular, innovative design, the ArgonCube. The related R&D work will proceed along two main directions; one aimed at on the assessment of the proposed modular detector design, the other on the exploitation of new signal readout methods. Such a strategy will provide high performance while being cost-effective and robust at the same time. According to our plans, we will firstly realize a detector prototype hosted in a cryostat that is a...

The ATLAS liquid argon calorimeter--status and expected performance

International Nuclear Information System (INIS)

Schacht, Peter

2004-01-01

For the ATLAS detector at the LHC, the liquid argon technique is exploited for the electromagnetic calorimetry in the central part and for the electromagnetic and hadronic calorimetry in the forward and backward regions. The construction of the calorimeter is well advanced with full cold tests of the barrel calorimeter and first endcap calorimeter only months away. The status of the project is discussed as well as the related results from beam test studies of the various calorimeter subdetectors. The results show that the expected performance meets the ATLAS requirements as specified in the ATLAS Technical Design Report

Effect of defoliation prior to a frost on postharvest respiration rate, extractable sucrose, and invert sugar concentration of sugarbeet

Science.gov (United States)

This study investigated the effect of defoliation prior to a frost on postharvest storage properties of sugarbeet (Beta vulgaris L.). Roots of plants with canopies intact until harvest were compared to roots of plants that had been defoliated prior to a frost on multiple harvest dates following a da...

Aclimatação ao frio e dano por geada em canola Acclimatization to cold and frost-injury in canola

Directory of Open Access Journals (Sweden)

Genei Antonio Dalmago

2010-09-01

Full Text Available O objetivo deste trabalho foi avaliar a influência da aclimatação ao frio sobre o dano causado pela geada em diferentes estádios fenológicos de genótipos de canola. Foram realizados cinco experimentos em ambiente controlado, em 2006, 2007 e 2008. Os fatores avaliados foram: genótipos, aclimatação (com; sem, intensidades de geada, estádios de desenvolvimento de plantas, regimes de aclimatação e regimes de geada. As variáveis avaliadas foram: queima de folhas, massa de matéria seca, estatura de plantas, duração de subperíodo, componentes de rendimento e rendimento de grãos. A aclimatação ao frio, antes da geada, resultou em menor queima de folhas e maior massa de matéria seca, em comparação a plantas não aclimatadas. As geadas foram prejudiciais a partir de -6°C no início do ciclo de desenvolvimento, principalmente em plantas não aclimatadas, e a partir de -4ºC na floração, com redução do número de síliquas e do número de grãos por síliqua. A aclimatação após as geadas não contribuiu para a tolerância da canola a esse evento. Geadas consecutivas não acarretaram maior prejuízo à canola. A aclimatação de plantas de canola antes da geada reduz os danos, principalmente quando a geada ocorre no início do desenvolvimento das plantas.The objective of this work was to evaluate the influence of cold acclimatization on frost damage at different phenological stages of canola genotypes. Five experiments were carried out under controlled conditions, in 2006, 2007, and 2008. The evaluated factors were: genotypes, acclimatization (with; without, frost gradient, plant developmental stages, acclimatization regimes and frost regimes. The evaluated variables were: leaf scorching symptoms, dry weight, plant height, length of subperiod, yield components and grain yield. The acclimatization before frost resulted in lesser leaf scorching symptoms and higher dry matter in comparison to plants not acclimated. Frosts were

Sodium evaporation into a forced argon flow

International Nuclear Information System (INIS)

Kumada, Toshiaki; Kasahara, Fumio; Ishiguro, Ryoji

1975-01-01

Evaporation from a rectangular sodium free surface into an argon flow was measured. Tests were carried out with varying sodium temperature, argon velocity and argon temperature respectively under conditions of fog formation being possible. In order to clarify the enhancement of evaporation by fog formation, convection heat transfer from a plate of the same geometry into an air flow was also measured. The evaporation rate and Sherwood number were compared with those predicted by both the heat transfer experiment and the theory proposed by Hill and Szekely, and also a comparison was run with the previously reported experimental results of sodium evaporation. As a result it was shown that the sodium evaporation rate in this experiment is at least four times as large as that predicted by the heat transfer experiment and varies almost linearly with the heat transfer rate and the sodium vapour pressure. (auth.)

Argon-41 production and evolution at the Oregon State University TRIGA Reactor (OSTR)

International Nuclear Information System (INIS)

Anellis, L.G.; Johnson, A.G.; Higginbotham, J.F.

1988-01-01

In this study, argon-41 concentrations were measured at various locations within the reactor facility to assess the accuracy of models used to predict argon-41 evolution from the reactor tank, and to determine the relationship between argon gas evolution from the tank and subsequent argon-41 concentrations throughout the reactor room. In particular, argon-41 was measured directly above the reactor tank with the reactor tank lids closed, at other accessible locations on the reactor top with the tank lids both closed and open, and at several locations on the first floor of the reactor room. These measured concentrations were then compared to values calculated using a modified argon-41 production and evolution model for TRIGA reactor tanks and ventilation values applicable to the OSTR facility. The modified model was based in part on earlier TRIGA models for argon-41 production and release, but added features which improved the agreement between predicted and measured values. The approximate dose equivalent rate due to the presence of argon-41 in reactor room air was calculated for several different locations inside the OSTR facility. These dose rates were determined using the argon-41 concentration measured at each specific location, and were subsequently converted to a predicted quarterly dose equivalent for each location based on the reactor's operating history. The predicted quarterly dose equivalent values were then compared to quarterly doses measured by film badges deployed as dose-integrating area radiation monitors at the locations of interest. The results indicate that the modified production and evolution model is able to predict argon-41 concentrations to within a factor of ten when compared to the measured data. Quarterly dose equivalents calculated from the measured argon-41 concentrations and the reactor's operating history seemed consistent with results obtained from the integrating area radiation monitors. Given the argon-41 concentrations measured

Improvement of helium characteristics using argon in cylindrical ion source

International Nuclear Information System (INIS)

Abdel salam, F.W.; El-Khabeary, H.; Abdel reheem, A.M.; Kassem, N.E.; Ahmed, M.M.

2004-01-01

the discharge characteristics of pure helium gas were measured at different pressures in the range of 10 -4 torr. in order o improve its characteristics, argon gas was added . different percentages of argon gas ,1%,2%,3%,4%,5%,10% and 20% were used at constant values of pressures . Measurements of the efficiency of the cylindrical ion source in case of adding different percentages of argon gas to pure helium gas were made . an optimum value of the output ion beam current was obtained when 2% argon gas was added to pure helium gas . an output ion beam current of 105 μA was obtained at a pressure of 7X10 -4 torr inside the vacuum chamber and discharge current of 0.6 m A

Characterisation of GERDA Phase-I detectors in liquid argon

Energy Technology Data Exchange (ETDEWEB)

Barnabe Heider, Marik; Schoenert, Stefan [Max-Planck-Institut fuer Kernphysik (Germany); Gusev, Konstantin [Russian Research Center, Kurchatov Institute (Russian Federation); Joint Institute for Nuclear Research (Russian Federation)

2009-07-01

GERDA will search for neutrinoless double beta decay in {sup 76}Ge by submerging bare enriched HPGe detectors in liquid argon. In GERDA Phase-I, reprocessed enriched-Ge detectors, which were previously operated by the Heidelberg-Moscow and IGEX collaborations, and reprocessed natural-Ge detectors from Genius-TF, will be redeployed. We have tested the operation and performance of bare HPGe detectors in liquid nitrogen and in liquid argon over more than three years with three non-enriched p-type prototype detectors. The detector handling and mounting procedures have been defined and the Phase-I detector technology, the low-mass assembly and the long-term stability in liquid argon have been tested successfully. The Phase-I detectors were reprocessed by Canberra Semiconductor NV, Olen, according to their standard technology but without the evaporation of a passivation layer. After their reprocessing, the detectors have been mounted in their low-mass holders and their characterisation in liquid argon performed. The leakage current, the counting characteristics and the efficiency of the detectors have been measured. The testing of the detectors was carried out in the liquid argon test stand of the GERDA underground Detector Laboratory (GDL) at LNGS. The detectors are now stored underground under vacuum until their operation in GERDA.

Potassium-argon dating in archaeology

Energy Technology Data Exchange (ETDEWEB)

McDougall, I. (Australian National Univ., Canberra (Australia). Research School of Earth Sciences)

1990-01-01

The potassium-argon (K-Ar) isotopic dating method can provide precise and accurate numerical ages on suitable rocks, especially igneous rocks, over a wide range of age from less than 100,000 years old, with no older limit. Together with its variants, the {sup 40}Ar/{sup 39}Ar technique, the K-Ar method is very useful for the numerical age calibration of stratigraphic sequences, including those containing archaeological or fossil material, in cases where appropriate rocks for dating are present. This brief review of the basis of the K-Ar dating method and the underlying assumptions, concludes with an example of its application to the Plio-Pleistocene stratigraphic sequence in the Turkana Basin, northern Kenya. By dating alkali feldspars separated from pumice blocks in tuffaceous beds, excellent age control has been obtained for the wealth of vertebrate fossils, including hominids, as well as archaeological materials that has been found in the sequence. (author).

Frost Monitoring and Forecasting Using MODIS Land Surface Temperature Data and a Numerical Weather Prediction Model Forecasts for Eastern Africa

Science.gov (United States)

Kabuchanga, Eric; Flores, Africa; Malaso, Susan; Mungai, John; Sakwa, Vincent; Shaka, Ayub; Limaye, Ashutosh

2014-01-01

Frost is a major challenge across Eastern Africa, severely impacting agricultural farms. Frost damages have wide ranging economic implications on tea and coffee farms, which represent a major economic sector. Early monitoring and forecasting will enable farmers to take preventive actions to minimize the losses. Although clearly important, timely information on when to protect crops from freezing is relatively limited. MODIS Land Surface Temperature (LST) data, derived from NASA's Terra and Aqua satellites, and 72-hr weather forecasts from the Kenya Meteorological Service's operational Weather Research Forecast model are enabling the Regional Center for Mapping of Resources for Development (RCMRD) and the Tea Research Foundation of Kenya to provide timely information to farmers in the region. This presentation will highlight an ongoing collaboration among the Kenya Meteorological Service, RCMRD, and the Tea Research Foundation of Kenya to identify frost events and provide farmers with potential frost forecasts in Eastern Africa.

Using the Pairs of Lines Broadened by Collisions with Neutral and Charged Particles for Gas Temperature Determination of Argon Non-Thermal Plasmas at Atmospheric Pressure

Directory of Open Access Journals (Sweden)

Cristina Yubero

2017-10-01

Full Text Available The spectroscopic method for gas temperature determination in argon non-thermal plasmas sustained at atmospheric pressure proposed recently by Spectrochimica Acta Part B 129 14 (2017—based on collisional broadening measurements of selected pairs of argon atomic lines, has been applied to other pairs of argon atomic lines, and the discrepancies found in some of these results have been analyzed. For validation purposes, the values of the gas temperature obtained using the different pairs of lines have been compared with the rotational temperatures derived from the OH ro-vibrational bands, using the Boltzmann-plot technique.

Behavior of Excited Argon Atoms in Inductively Driven Plasmas

CERN Document Server

Hebner, G A

1999-01-01

Laser induced fluorescence has been used to measure the spatial distribution of the two lowest energy argon excited states, 1s sub 5 and 1s sub 4 , in inductively driven plasmas containing argon, chlorine and boron trichloride. The behavior of the two energy levels with plasma conditions was significantly different, probably because the 1s sub 5 level is metastable and the 1s sub 4 level is radiatively coupled to the ground state but is radiation trapped. The argon data is compared with a global model to identify the relative importance of processes such as electron collisional mixing and radiation trapping. The trends in the data suggest that both processes play a major role in determining the excited state density. At lower rfpower and pressure, excited state spatial distributions in pure argon were peaked in the center of the discharge, with an approximately Gaussian profile. However, for the highest rfpowers and pressures investigated, the spatial distributions tended to flatten in the center of the disch...

Characterization of DC argon plasma jet at atmospheric pressure

International Nuclear Information System (INIS)

Yan Jianhua; Ma Zengyi; Pan Xinchao; Cen Kefa; Bruno, C

2006-01-01

An original DC double anode plasma torch operating with argon at atmospheric pressure which provides a long time and highly stable plasma jet is analyzed through its electrical and optical signals. Effects of gas flow rate and current intensity on the arc dynamics behaviour are studied using standard diagnostic tools such as FFT and correlation function. An increasing current-voltage characteristic is reported for different argon flow rates. It is noted that the takeover mode is characteristic for argon plasma jet and arc fluctuations in our case are mainly induced by the undulation of torch power supply. Furthermore, the excitation temperatures and electron densities of the plasma jet inside and outside the arc chamber have been determined by means of optical emission spectroscopy (OES). The criteria for the existence of local thermodynamic equilibrium (LTE) in plasma is then discussed. The results show that argon plasma jet at atmospheric pressure under our experimental conditions is close to LTE. (authors)

Development and Validation of the Frost Multidimensional Perfectionism Scale--Brief

Science.gov (United States)

Burgess, Alexandra M.; Frost, Randy O.; DiBartolo, Patricia Marten

2016-01-01

Twenty-five years ago, one of the first empirically validated measures of perfectionism, the Frost et al. Multidimensional Perfectionism Scale (F-MPS) was published. Since that time, psychometric studies of the original F-MPS have provided a plethora of evidence to support the potential development of a shorter yet still psychometrically robust…

Effects of fin pitch and array of the frost layer growth on extended surface of a heat exchanger

International Nuclear Information System (INIS)

Yang, Dong Keun; Lee, Kwan Soo

2003-01-01

This paper presents the effects of the fin array and pitch on the frost layer growth of a heat exchanger. The numerical results are compared with experimental data of a cold plate to validate the present model, and agree well with experimental data within a maximum error of 8%. The characteristics of the frost formation on staggered fin array are somewhat different from those of in-line array. For fin pitch below 10 mm, the frost layer growth of second fin in the staggered array is affected by that of first fin. The heat transfer of single fin deteriorate with decreasing fin pitch regardless of fin array, however, the thermal performance of a heat exchanger, considering increase of heat surface area, becomes better

Nitrogen split dose fertilization, plant age and frost effects on phytochemical content and sensory properties of curly kale (Brassica oleracea L. var. sabellica).

Science.gov (United States)

Groenbaek, Marie; Jensen, Sidsel; Neugart, Susanne; Schreiner, Monika; Kidmose, Ulla; Kristensen, Hanne L

2016-04-15

We investigated how concentrations of sensory relevant compounds: glucosinolates (GLSs), flavonoid glycosides, hydroxycinnamic acid derivatives and sugars in kale responded to split dose and reduced nitrogen (N) fertilization, plant age and controlled frost exposure. In addition, frost effects on sensory properties combined with N supply were assessed. Seventeen week old kale plants showed decreased aliphatic GLSs at split dose N fertilization; whereas reduced N increased aliphatic and total GLSs. Ontogenetic effects were demonstrated for all compounds: sugars, aliphatic and total GLSs increased throughout plant development, whereas kaempferol and total flavonoid glycosides showed higher concentrations in 13 week old plants. Controlled frost exposure altered sugar composition slightly, but not GLSs or flavonoid glycosides. Reduced N supply resulted in less bitterness, astringency and pungent aroma, whereas frost exposure mainly influenced aroma and texture. N treatment explained most of the sensory variation. Producers should not rely on frost only to obtain altered sensory properties. Copyright © 2015 Elsevier Ltd. All rights reserved.

Research on frost formation in air source heat pump at cold-moist conditions in central-south China

International Nuclear Information System (INIS)

Gong, Guangcai; Tang, Jinchen; Lv, Dongyan; Wang, Hongjin

2013-01-01

Highlights: ►A dynamic evaporator model is built up. ► The model involves the ratio of the latent heat to sensible heat of wet air. ►A correlation considering d eq is shown below to predict frost accumulation: (M fr v 3 )/(Ψd eq 2 ) =((T a )/(T w ) ) 0.1 ((vτ)/(d eq ) ) 0.7 (l/(d eq ) ) 1.378 X a 1.228 . ►The changing ratio can characterize the early development of system performance. ►The changing ratio can characterize the early development of frost accumulation. -- Abstract: A dynamic evaporator model of air source heat pump (ASHP), considering the ratio of the latent heat to sensible heat of wet air, is presented to analyze the performance of ASHP under frosting. The performance parameters, such as the heating capacity, COP and the outlet temperature of compressor, are simulated with CYCLEPAD. Then a semi-empirical correlation that predicts frost accumulation on the air-side of fin-tube heat exchanger is developed with dimensionless analysis and also modified by a test conducted under cold-moist conditions in winter. In addition, eight influence factors are considered involving the ambient conditions and structures of heat exchanger, whose effects are analyzed as well. Among them, the equivalent diameter of air flow cross-section in fin-tube d eq is especially proposed. Lastly, the relationships between the ratio, the performance parameters and the frost accumulation are discussed in this paper, followed by an evaluation of an optimal defrosting time interval to improve the ASHP’s energy efficiency and operational reliability at cold-moist conditions in central-south China.

The neutral beam test facility cryopumping operation: preliminary analysis and design of the cryogenic system

International Nuclear Information System (INIS)

Gravil, B.; Henry, D.; Cordier, J.J.; Hemsworth, R.; Van Houtte, D.

2004-01-01

The ITER neutral beam heating and current drive system is to be equipped with a cryosorption cryopump made up of 12 panels connected in parallel, refrigerated by 4.5 K 0.4 MPa supercritical helium. The pump is submitted to a non homogeneous flux of H 2 or D 2 molecules, and the absorbed flux varies from 3 Pa.m -3 .s -1 to 35 Pa.m -3 .s -1 . In the frame of the 'ITER first injector and test facility CSU-EFDA task' (TW3-THHN-IITF1), the ITER reference cryo-system and cryo-plant designs have been assessed and compared to optimised designs devoted to the Neutral Beam Test Facility (NBTF). The 4.5 K cryo-panel, which has a mass of about 1000 kg, must be periodically regenerated up to 90 K and occasionally to 470 K. The cool-down time after regeneration depends strongly on the refrigeration capacity. Fast regeneration and cool-down of the cryo-panels are not considered a priority for the test facility operation, and an analysis of the consequences of a limited cold power refrigerator on the cooling down time has been carried out and will be discussed. This paper presents a preliminary evaluation of the NBTF cryo-plant and the associated process flow diagram. (authors)

First measurement of the ionization yield of nuclear recoils in liquid argon

Energy Technology Data Exchange (ETDEWEB)

Joshi, T. [Univ. of California, Berkeley, CA (United States). Dept. of Nuclear Engineering; Lawrence Livermore National Laboratory (LLNL), Livermore, CA (United States); Sangiorgio, Samuele [Lawrence Livermore National Laboratory (LLNL), Livermore, CA (United States); Bernstein, A. [Lawrence Livermore National Laboratory (LLNL), Livermore, CA (United States); Foxe, Michael P. [Lawrence Livermore National Laboratory (LLNL), Livermore, CA (United States); Pennsylvania State Univ., University Park, PA (United States). Dept. of Mechanical and Nuclear Engineering; Hagmann, Chris [Lawrence Livermore National Laboratory (LLNL), Livermore, CA (United States); Jovanovic, Igor [Pennsylvania State Univ., University Park, PA (United States). Dept. of Mechanical and Nuclear Engineering; Kazkaz, K. [Lawrence Livermore National Laboratory (LLNL), Livermore, CA (United States); Mozin, Vladimir V. [Lawrence Livermore National Laboratory (LLNL), Livermore, CA (United States); Norman, E. B. [Univ. of California, Berkeley, CA (United States). Dept. of Nuclear Engineering; Lawrence Livermore National Laboratory (LLNL), Livermore, CA (United States); Pereverzev, S. V. [Lawrence Livermore National Laboratory (LLNL), Livermore, CA (United States); Rebassoo, Finn O. [Lawrence Livermore National Laboratory (LLNL), Livermore, CA (United States); Sorensen, Peter F. [Lawrence Livermore National Laboratory (LLNL), Livermore, CA (United States)

2014-05-01

Liquid phase argon has long been used as a target medium for particle detection via scintillation light. Recently there has been considerable interest in direct detection of both hypothetical darkmatter particles and coherent elastic neutrino nucleus scattering. These as-yet unobserved neutral particle interactions are expected to result in a recoiling argon atom O(keV), generally referred to in the literature as a nuclear recoil. This prompts the question of the available electromagnetic signal in a liquid argon detector. In this Letter we report the first measurement of the ionization yield (Qy), detected electrons per unit energy, resulting from nuclear recoils in liquid argon, measured at 6.7 keV. This is also the lowest energy measurement of nuclear recoils in liquid argon.

There is no direct relationship between N-status and frost hardiness in needles of NH3-exposed Scots pine seedlings

NARCIS (Netherlands)

Clement, JMAM; Venema, JH; Van Hasselt, PR

2000-01-01

The effect of short-term atmospheric ammonia deposition on frost hardening of needles of three-month-old seedlings of Scots pine (Pinus sylvestris L.) was studied. Plants were frost hardened under short day and moderate temperature conditions in the laboratory during exposure to gaseous NH3

An unusual case of frost bite autoamputation of toes.

Science.gov (United States)

Wani, Adil Hafeez; Mohsin, Mir; Darzi, Mohammed Ashraf; Zaroo, Mohammed Inam; Bashir, Sheikh Adil; Zargar, Haroon Rashid; Rasool, Altaf; Bijli, Mohammed Akram; Dar, Hameedullah; Farooq, Peerzada Omar; Ahmed, Sheikh Tariq

2008-12-16

We report a case of a 15 year old young female who suffered autoamputation of left mid foot and four digits of right foot following repeated application of snow to relieve the pain in her frost bitten feet. The sociodemographic background, cause, resulting injury and subsequent management are discussed. Such injuries are relatively rare but awareness of the risk of this type of injury is important.

Thermal conductivity in an argon arc at atmospheric pressure

NARCIS (Netherlands)

Bol, L.; Timmermans, C.J.; Schram, D.C.

1984-01-01

The thermal conductivity of an argon plasma has been determined in a phi 5 mm wall stabilized atmospheric argon arc in the temperature range from 10000 to 16000 K. The calculations are based on the energy balance, and include non-LTE effects like ambipolar diffusion and overpopulation of the ground

The potential importance of frost flowers, recycling on snow, and open leads for ozone depletion events

Directory of Open Access Journals (Sweden)

M. Piot

2008-05-01

Full Text Available We present model studies with the one-dimensional model MISTRA to investigate the potential role of frost flowers, recycling on snow, and open leads in the depletion of tropospheric ozone in the Arctic spring. In our model, we assumed frost flower aerosols to be the major source of bromine. We show that a major ozone depletion event can be satisfactorily reproduced only if the recycling on snow of deposited bromine into gas phase bromine is assumed. In the model, this cycling is more efficient than the bromine explosion process and maintains sufficiently high levels of bromine to deplete ozone down to few nmol mol⁻¹ within four days. We assessed the influence of different surface combinations (open lead/frost flowers on the chemistry in the model. Results showed noticeable modifications affecting the composition of aerosols and the deposition velocities. A model run with a series of coupled frost flower fields and open leads, separated by large areas of snow, showed results comparable with field observations. In addition, we studied the effects of modified temperature of either the frost flower field or the ambient airmass. A warmer frost flower field increases the relative humidity and the aerosol deposition rate. The deposition/re-emission process gains in importance, inducing more reactive bromine in the gas phase, and a stronger ozone depletion. A decrease of 1K in airmass temperature shows in our model that the aerosol uptake capacities of all gas phase species substantially increases, leading to enhanced uptake of acids from the gas phase. Consequently, the so-called bromine explosion accelerated and O₃ mixing ratios decreased. In our model representation, variations in wind speed affected the aerosol source function and influenced the amount of bromine in the atmosphere and thus the ozone depletion strength. Recent studies have suggested the important role of the precipitation of calcium carbonate (CaCO₃

Studies on EOS of shock-generated argon plasmas

International Nuclear Information System (INIS)

Wang Fanhou; Jing Fuqian

2001-01-01

The equation of state for argon plasma, covering the thermodynamic states of 10000-30000 K in temperature and 0.0133-0.166 GPa in pressure, is computed using the Saha model and Debye-Huckel correction. Comparisons of the measured EOS with the calculated ones demonstrate the Saha model and Debye-Huckel correction can be used to well describe the essential behavior of argon plasma under the thermodynamic condition above-mentioned

Neutrino-argon interactions in the T2K near detector

Energy Technology Data Exchange (ETDEWEB)

Koch, Lukas; Radermacher, Thomas; Roth, Stefan; Steinmann, Jochen [III. Physikalisches Institut B, RWTH Aachen (Germany)

2016-07-01

The T2K near detector employs three large, argon-filled TPCs with a total fiducial volume of about 10 m{sup 3} at ambient pressure. These TPCs have been exposed to the intense T2K muon-neutrino beam since the start of the experiment. The beam has a mean neutrino energy of 600 MeV and so far, data corresponding to over 6 . 10{sup 20}(4 . 10{sup 20}) protons on target was recorded in neutrino (anti-neutrino) mode. We expect about 600 charged current neutrino-argon interactions in the data. That enables us to do the world's first neutrino-Argon cross section measurement in gaseous argon, thus making an important contribution to constraining nuclear interaction models for future neutrino oscillation measurements. This talk describes the physics goals and present the current status of the analysis.

Cross-Cultural Validity of the Frost Multidimensional Perfectionism Scale in Korea

Science.gov (United States)

Lee, Dong-gwi; Park, Hyun-joo

2011-01-01

This study with 213 South Korean college students (113 men) examined the cross-cultural generalizability of (a) the factor structure of the Frost Multidimensional Perfectionism Scale (F-MPS) and (b) the existence of adaptive perfectionists, maladaptive perfectionists, and nonperfectionists. A confirmatory factor analysis did not support the…

Thermal information regarding the cooldown and operation of liquid argon calorimeters

International Nuclear Information System (INIS)

Rucinski, R.A.; Cooper, W.E.; Dixon, K.D.; Krempetz, K.J.; Mulholland, G.T.; Primdahl, K.; Urbin, J.B.

1993-07-01

Three liquid argon calorimeters were cooled down and operated as part of the D-Zero detector at Fermi National Accelerator laboratory. The largest vessel contains 248 metric tons of uranium and copper plates and 19 kL (5000 gal.) of liquid argon. The other two vessels are mirror images, each containing 185 metric tons of uranium and stainless steel plates and 12.1 kL (3200 gal.) of liquid argon. The cool down was accomplished by convection heat transfer between boiling liquid nitrogen filled finned heat exchangers and argon gas inside the vessels. Information regarding the general internal geometry of the calorimeters, cool down, operation, and steady state heat loads will be presented

Two-dimensional model of coupled heat and moisture transport in frost-heaving soils

International Nuclear Information System (INIS)

Guymon, G.L.; Berg, R.L.; Hromadka, T.V.

1984-01-01

A two-dimensional model of coupled heat and moisture flow in frost-heaving soils is developed based upon well known equations of heat and moisture flow in soils. Numerical solution is by the nodal domain integration method which includes the integrated finite difference and the Galerkin finite element methods. Solution of the phase change process is approximated by an isothermal approach and phenomenological equations are assumed for processes occurring in freezing or thawing zones. The model has been verified against experimental one-dimensional freezing soil column data and experimental two-dimensional soil thawing tank data as well as two-dimensional soil seepage data. The model has been applied to several simple but useful field problems such as roadway embankment freezing and frost heaving

Clinton, Peck and Frost -- The dawn of North American boletology

Science.gov (United States)

Ernst E. Both; Beatriz. Ortiz-Santana

2010-01-01

George W. Clinton (a founder and first president of the Buffalo Society of Natural Sciences) launched the mycological career of Peck by obtaining for him the position of botanist of the New York State Cabinet of Natural History and he was responsible for the publication of Frost's "Boleti of New England." This paper discusses the interaction between Peck...

WARP: a double phase argon programme for dark matter detection

International Nuclear Information System (INIS)

Ferrari, N

2006-01-01

WARP (Wimp ARgon Programme) is a double phase Argon detector for Dark Matter search under construction at Laboratori Nazionali del Gran Sasso. We present recent results obtained operating a prototype with a sensitive mass of 2.3 litres deep underground

Mathematical identification of homogenisation processes in argon stirred ladle

Directory of Open Access Journals (Sweden)

K. Michalek

2009-10-01

Full Text Available Mathematical models processed results of experimental investigation obtained during ladle gas argon bubbling realized by stir elements situated in the ladle bottom. Exact theoretical description of processes occurring at argon bubbling into steel would be very complex and it would lead to a system of non-linear partial differential equations describing transfer of momentum, heat, components, and with excitation function in the form of equation of so called deterministic chaos (argon bubbling. On the basis of pouring ladle model diagram and concentrations courses, the simplified linear physically adequate model was proposed, which described behavior of steel concentration in pouring ladle during its bubbling. The analysed process was understood in the form of a cybernetic model.

Features of copper etching in chlorine-argon plasma

International Nuclear Information System (INIS)

Efremov, A.M.; Svettsov, V.I.

1995-01-01

Chlorine mixtures with inert gases including argon exhibit promise as plasma feed gases for etching metals and semiconductors in the microelectronics industry. It was shown that even strong dilution of reactive gas with an inert gas (up to 80-90% of the latter) has virtually no effect in decreasing the rate of plasma etching of materials such as silicon and gallium arsenide, compared to etching in pure chlorine. The principal reactive species responsible for etching these substrates are chlorine atoms therefore, a possible explanation of the effect is an increase in the rate of bulk generation of chlorine atoms in the presence of argon. In this work the authors studied the influence of argon on the rate of copper etching in chlorine, because copper, unlike the above substrates, reacts effectively not only with the atoms but with the ground-state molecules of chlorine

EVALUATION OF FROST HEAVE ON WASTE TRANSFER LINES WITH SHALLOW DEPTHS IN DST (DOUBLE SHELL TANK) FARMS

Energy Technology Data Exchange (ETDEWEB)

HAQ MA

2009-05-12

The purpose of this document is to evaluate the effect of frost heave on waste transfer lines with shallow depths in DST farms. Because of the insulation, well compacted sandy material around waste transfer lines, the type of sandy and gravel soil, and relatively low precipitation at Hanford site, it is concluded that waste transfer lines with one foot of soil covers (sandy cushion material and insulation) are not expected to undergo frost heave damaging effects.

Mapping of QTLs for frost tolerance and heading time using SSR ...

African Journals Online (AJOL)

STORAGESEVER

2008-10-19

Oct 19, 2008 ... using SSR markers in bread wheat. Omid Sofalian1*, Seyyed A. ... Key words: Bread wheat, frost tolerance, heading time, QTL mapping, single marker analysis, SSR. INTRODUCTION. Abiotic stresses are crucial ... cultivars are divided into two types (winter and spring growth habit) depending on their need ...

Diffusion of lithium ions in argon

International Nuclear Information System (INIS)

Stefansson, T.

1983-01-01

Published measurements of transport coefficients for Li + ions in argon seem to be limited to the mobility and the longitudinal diffusion coefficient in the field-to-density ratio range at and below 200 Td 1-5 . In this paper results are presented from measurements of the transverse diffusion coefficient to mobility ratio (Dsub(T)/μ) for Li + ions in argon in the field-to-density ratio range 10 < E/n < 800 Td. The measurements were made with a drift tube mass spectrometer at a gas temperature of 295 +- 1 K using the modified Townsend method of Skullerud. The experimental curve is compared to a calculation by H.R. Skullerud in the same proceedings. (G.Q.)

Liquid Argon TPC Signal Formation, Signal Processing and Hit Reconstruction

Energy Technology Data Exchange (ETDEWEB)

Baller, Bruce [Fermilab

2017-03-11

This document describes the early stage of the reconstruction chain that was developed for the ArgoNeuT and MicroBooNE experiments at Fermilab. These experiments study accelerator neutrino interactions that occur in a Liquid Argon Time Projection Chamber. Reconstructing the properties of particles produced in these interactions requires knowledge of the micro-physics processes that affect the creation and transport of ionization electrons to the readout system. A wire signal deconvolution technique was developed to convert wire signals to a standard form for hit reconstruction, to remove artifacts in the electronics chain and to remove coherent noise.

The radiolytic formation of nitric acid in argon/air/water systems

International Nuclear Information System (INIS)

May, R.; Stinchcombe, D.; White, H.P.

1992-01-01

The extent of nitric acid formation in the γ-radiolysis of argon/air/water mixtures has been assessed. The yields of nitric acid are found to increase as water vapour pressure is increased but are lower in the presence of a discrete water phase. G values for the formation of nitric acid from argon/air mixtures based on energy absorbed in the air are increased in the presence of argon but the yields in an atmosphere of argon containing small amounts of moist air are smaller than from an atmosphere of moist air alone. The G value for nitric acid formation from pure air in the presence of a distinct water phase is 2, based on energy absorbed in the air. (author)

Prospects for obtaining a superconducting filter to purify oxygen from argon

International Nuclear Information System (INIS)

Sawai, Yuichi; Ishizaki, Kozo; Yayashi, Shigeki; Jain, R.

1993-01-01

A possible superconducting filter, through which argon can pass and oxygen can not pass, is discussed theoretically. Oxygen and argon are paramagnetic and diamagnetic materials, respectively. The mixture of oxygen and argon can be separated in a magnetic field higher than 4 T 2 /m of BdB/dx, where B is the magnetic flux density and dB/dx is its gradient. Such a magnetic field can be obtained by a superconducting filter. Because magnetic flux does not pass through a superconducting body of the filter, and instead does along the penetrating pores, B in the penetrating pores and dB/dx on the surface of the filter are very high, which allows separation of argon from oxygen. 3 refs., 3 figs

Frost Resistance and Permeability of Cement Stabilized Gravel used as Filling Material for Pearl-Chain Bridges

DEFF Research Database (Denmark)

Lund, Mia Schou Møller; Hansen, Kurt Kielsgaard; Hertz, Kristian Dahl

2014-01-01

several requirements on its moisture properties. In this paper the frost resistance, the liquid water permeability and the water vapour permeability of cement stabilized gravel are examined for two different cement contents. It is found that a small increase in cement content from 4% to 5% increases...... the 28-days compressive strength from 6.2 MPa to 12.3 MPa. The frost resistance of cement stabilized gravel with 5% cement content is better than for cement stabilized gravel with 4% cement content. The liquid water permeability coefficient and the water vapour permeability coefficient are significantly...

Mapping of QTLs for frost tolerance and heading time using SSR ...

African Journals Online (AJOL)

Selection for complex genetic traits, such as frost tolerance, can be simplified in plant breeding programs when linked markers were detected. The use of microsatellite markers for tagging and mapping important genes or QTLs is a goal in wheat genetic projects. In this study, 200 microsatellite markers were studied and ...

Suppression of Frost Nucleation Achieved Using the Nanoengineered Integral Humidity Sink Effect.

Science.gov (United States)

Sun, Xiaoda; Rykaczewski, Konrad

2017-01-24

Inhibition of frost formation is important for increasing efficiency of refrigeration systems and heat exchangers, as well as for preventing the rapid icing over of water-repellant coatings that are designed to prevent accumulation of rime and glaze. From a thermodynamic point of view, this task can be achieved by either increasing hydrophobicity of the surface or decreasing the concentration of water vapor above it. The first approach has been studied in depth, but so far has not yielded a robust solution to the problem of frost formation. In this work, we systematically explore how frost growth can be inhibited by controlling water vapor concentration using bilayer coatings with a porous exterior covering a hygroscopic liquid-infused layer. We lay the theoretical foundation and provide experimental validation of the mass transport mechanism that governs the integral humidity sink effect based on this coating platform as well as reveal intriguing sizing effects about this system. We show that the concentration profile above periodically spaced pores is governed by the sink and source concentrations and two geometrical parameters: the nondimensional pore size and the ratio of the pore spacing to the boundary layer thickness. We demonstrate that when the ratio of the pore spacing to the boundary layer thickness vanishes, as for the nanoporous bilayer coatings, the entire surface concentration becomes uniform and equal to the concentration set by the hygroscopic liquid. In other words, the surface concentration becomes completely independent of the nanopore size. We identified the threshold geometrical parameters for this condition and show that it can lead to a 65 K decrease in the nucleation onset surface temperature below the dew point. With this fundamental insight, we use bilayer coatings to nanoengineer the integral humidity sink effect to provide extreme antifrosting performance with up to a 2 h delay in nucleation onset at 263 K. The nanoporous bilayer

Spatio-temporal dynamics of a pulsed microwave argon plasma: ignition and afterglow

International Nuclear Information System (INIS)

Carbone, Emile; Sadeghi, Nader; Vos, Erik; Hübner, Simon; Van Veldhuizen, Eddie; Van Dijk, Jan; Nijdam, Sander; Kroesen, Gerrit

2015-01-01

In this paper, a detailed investigation of the spatio-temporal dynamics of a pulsed microwave plasma is presented. The plasma is ignited inside a dielectric tube in a repetitively pulsed regime at pressures ranging from 1 up to 100 mbar with pulse repetition frequencies from 200 Hz up to 500 kHz. Various diagnostic techniques are employed to obtain the main plasma parameters both spatially and with high temporal resolution. Thomson scattering is used to obtain the electron density and mean electron energy at fixed positions in the dielectric tube. The temporal evolution of the two resonant and two metastable argon 4s states are measured by laser diode absorption spectroscopy. Nanosecond time-resolved imaging of the discharge allows us to follow the spatio-temporal evolution of the discharge with high temporal and spatial resolution. Finally, the temporal evolution of argon 4p and higher states is measured by optical emission spectroscopy. The combination of these various diagnostics techniques gives deeper insight on the plasma dynamics during pulsed microwave plasma operation from low to high pressure regimes. The effects of the pulse repetition frequency on the plasma ignition dynamics are discussed and the plasma-off time is found to be the relevant parameter for the observed ignition modes. Depending on the delay between two plasma pulses, the dynamics of the ionization front are found to be changing dramatically. This is also reflected in the dynamics of the electron density and temperature and argon line emission from the plasma. On the other hand, the (quasi) steady state properties of the plasma are found to depend only weakly on the pulse repetition frequency and the afterglow kinetics present an uniform spatio-temporal behavior. However, compared to continuous operation, the time-averaged metastable and resonant state 4s densities are found to be significantly larger around a few kHz pulsing frequency. (paper)

A new argon gas-based device for the treatment of keloid scars with the use of intralesional cryotherapy

NARCIS (Netherlands)

van Leeuwen, M.C.E.; Bulstra, A.E.J.; van Leeuwen, P.A.M.; Niessen, F.B.

2014-01-01

Background: Intralesional (IL) cryotherapy is a new promising technique for the treatment of keloid scars, in which the scar is frozen from inside. Multiple devices are available, mostly based on a simple liquid nitrogen Dewar system, which have a limited freezing capacity. Argon gas-based systems

Snow and frost measurements in a watershed-management research program

Science.gov (United States)

Richard S. Sartz

1957-01-01

I am going to tell you about our snow and frost work on the Hubbard Brook Experimental Forest in the White Mountains of New Hampshire. Hubbard Brook is one of several experimental areas scattered throughout the country on which personnel of the United States Forest Service are seeking to learn how different kinds of forests and methods of managing them affect...

Luminescence decay in condensed argon under high energy excitation

International Nuclear Information System (INIS)

Carvalho, M.J.; Klein, G.

1978-01-01

α and β particles were used to study the luminescence of condensed argon. The scintillation decay has always two components independently of the phase and the kind of the exciting particles. Decay time constants are given for solid, liquid and also gaseous argon. Changes in the relative intensity values of the two components are discussed in terms of track effects

A preliminary report on methods of measuring and reducing Argon-41 production by a TRIGA reactor

International Nuclear Information System (INIS)

Smith, W.L.

1972-01-01

Methods to accurately determine and techniques to reduce the Argon-41 released from the one-megawatt Geological Survey TRIGA Reactor facility have been developed. Knowledge of the composition of the exhaust-gas effluent is of prime importance to the U.S. Geological Survey in minimizing all radioactive releases to the environment. The counting systems and control measures have enabled the Geological Survey TRIGA Reactor staff to reduce the amount of Argon-41 released from the facility by a factor of two, with no reduction in operation level of the reactor. The counting system has also enabled the staff to categorize the principal sources of Argon-41. Under normal conditions, a fully-loaded rotating-specimen rack is by far the largest contributor. With the current counting system, 10 -7 microcuries per cubic centimeter can be detected in the exhaust stack. It is intended to further improve this system to increase both the sensitivity and the reliability. The sensitivity is expected to be increased by utilizing a larger counting volume. To improve the reliability, it is planned to fabricate a loop parallel to the exhaust system, eliminating the need for a separate pump. (author)

On the dependence of structural and sensing properties of sputtered MoO{sub 3} thin films on argon gas flow

Energy Technology Data Exchange (ETDEWEB)

Khojier, K., E-mail: k_khojier@yahoo.com [Department of Physics, Chalous Branch, Islamic Azad University, Chalous (Iran, Islamic Republic of); Savaloni, H. [Department of Physics, University of Tehran, North Kargar Street, Tehran (Iran, Islamic Republic of); Zolghadr, S. [Department of Physics, Faculty of Science, Central Tehran Branch, Islamic Azad University, Tehran (Iran, Islamic Republic of)

2014-11-30

Highlights: • MoO{sub 3} thin films are sputter coated and their structure are analyzed. • Effect of argon gas flow on the structural and some properties is studied. • CO sensing ability of MoO{sub 3} increases with argon gas flow. • MoO{sub 3} nano-strain decreases with argon gas flow. - Abstract: Nitrogen and carbon oxides (CO, NO and NO{sub 2}), released from combustion facilities and automobiles, are known to be extremely harmful to the human body and also are the main cause of air pollution. Therefore, effective methods to monitor and suppress the carbon and nitrogen oxides have been highly demanded for atmospheric environmental measurements and controls. It is known that molybdenum oxide (MoO{sub 3}) can be a good semiconductor material for use as a gas sensor in monitoring CO, NO and NO{sub 2}. In this paper we report the structural characteristics and sensing properties of the sputtered MoO{sub 3} thin films as a function of argon gas flow. MoO{sub 3} thin films were deposited by DC reactive magnetron sputtering technique on glass substrates at different argon gas flows in the range of 5–20 sccm. X-ray diffraction (XRD) analysis was used for studying crystallographic structure. XRD results showed that all of our films were of polycrystalline structure and of α-MoO{sub 3} stable orthorhombic phase. Results also showed that crystallite size increases while compressive nano-strain in the structure of the films decreases with increasing the argon gas flow. Atomic force microscope and the field emission scanning electron microscope studies showed granular structures for all samples, which increased in size consistent with the XRD results, with argon gas flow, while the surface roughness of the films also increased with argon gas flow. Chemical composition study showed optimum reaction between oxygen and molybdenum atoms for films produced at 15 sccm flow of argon gas. The electrical response of samples was measured in the vacuum and the CO

Urbanization may reduce the risk of frost damage to spring flowers: A case study of two shrub species in South Korea.

Science.gov (United States)

Gim, Hyeon-Ju; Ho, Chang-Hoi; Kim, Jinwon; Lee, Eun Ju

2018-01-01

Regional warming, owing to urbanization, leads to earlier spring phenological events and may expose plants to hard freeze damage. This study examined the influence of urbanization on the risk of frost damage to spring flowers in South Korea from 1973 to 2015. For the analysis period, we categorized 25 cities into two groups: those showing rapid population growth (rPG) ≥ 200,000, including 13 cities, and those showing no or decreased population growth (nPG), including 12 cities. We then investigated the time from the last frost dates (LFDs) in spring to the first flowering dates (FFDs) for each group. The rPG group experienced significant spring warming of 0.47°C per decade, resulting in earlier LFDs and FFDs. For this group, the advancement of LFD was more rapid than that of FFD, and the days between these two dates increased from 0.42 to 0.47 days per decade, implying a reduced risk of frost damage. Spring warming and the advancement of FFDs and LFDs were relatively small for the nPG group, and the LFDs were rather delayed. Consequently, the days between LFDs and FFDs were reduced from -1.05 to -1.67 days per decade, indicating an increased risk of frost damage. The contrasting changes in the frost-damage risk between the two city groups can be attributed to distinct urban warming at night, which makes the LFDs substantially earlier in the rPG group. Therefore, this study suggests that the warming associated with urbanization may lessen the risk of spring frost damage to plants in rapidly growing urban areas.

Drought and frost tolerance in rhododendron collection of the Mlyňany Arboretum (Slovakia: a screening for future climate

Directory of Open Access Journals (Sweden)

Ferus Peter

2017-12-01

Full Text Available Rhododendrons are jewels of the Mlyňany Arboretum, Institute of Forest Ecology of the Slovak Academy of Sciences (IFE SAS. Blossoming in May, they attract thousands of visitors. But recently these woody plants have much suffered from climatic extremes such as summer droughts and winter frosts, associated with the advancing climate change. To assess the rhododendron collection’s stability, its drought and frost injury level were tested in field, in summer 2015 and winter 2017, respectively. The tested parameters were: leaf wilting and electrolyte leakage combined with shrub leaf area, insolation level and overall health state. We found that the drought effect was strong or very strong in only ca. 30% rhododendron species and ca. 10% rhododendron cultivars, and that around 60% shrubs showed no or only moderate symptoms of water deficit. The drought injury level was only associated with the genotype. The most tolerant / sensitive genotypes, commonly occurring in the park, were: R. catawbiense, R. ponticum, R. smirnowii, cv. ‘Boursault’, cv. ‘Cunningham’s White’ and cv. ‘Purpureum Elegans’ / R. fortunei and cv. ‘Tamarindos’. On the other hand, the most frequent response to frost in the observed rhododendron genotypes was moderate injury (28 and 37% for species and cultivars, respectively, nevertheless more than 18% species and almost 6% cultivars exhibited strong frost damage. Despite absence of significant differences in the factor-response between the species, we may suggest this decreasing sequence of the genotypes ordered according to their frost resistance: genotypes: cv. ‘Cunningham’s White’ > R. decorum > R. fortunei and cv. ‘Duke of York’ > R. smirnowii > cvs. ‘Purpureum Elegans’ and ‘Tamarindos’ > R. macrophyllum and cv. ‘Nova Zembla’ > R. catawbiense > R. ponticum. These results have been compared with similar works in rhododendron species/cultivars as well as suggested species drought/frost

Formation of carbon nanostructures using acetylene, argon-acetylene and argon-hydrogen-acetylene plasmas

International Nuclear Information System (INIS)

Marcinauskas, L.; Grigonis, A.; Minialga, V.; Marcinauskas, L.; Valincius, V.

2013-01-01

The films prepared in argon-acetylene plasma are attributed to graphite-like carbon films. Addition of the hydrogen decreases growth rate and the surface roughness of the films and lead to the formation of nanocrystalline graphite. The carbon nanotubes were formed at low (≤ 450°C; p = 40 Pa) temperature in pure acetylene plasma. (authors)

Man, Nature, and Art in Robert Frost's Poetry | Elimimian | Lwati: A ...

African Journals Online (AJOL)

... and it is along these three aesthetic trajectories that this essay will be divided and addressed. In discussing these areas, an attempt will be made to examine the diversity of Frost's lyricism, the poet's sense of Romanticism, and the particular rhetorical and poetic devices which he employs to elucidate or illuminate his work.

Metabolite profiling during cold acclimation of Lolium perenne genotypes distinct in the level of frost tolerance.

Science.gov (United States)

Bocian, Aleksandra; Zwierzykowski, Zbigniew; Rapacz, Marcin; Koczyk, Grzegorz; Ciesiołka, Danuta; Kosmala, Arkadiusz

2015-11-01

Abiotic stresses, including low temperature, can significantly reduce plant yielding. The knowledge on the molecular basis of stress tolerance could help to improve its level in species of relatively high importance to agriculture. Unfortunately, the complex research performed so far mainly on model species and also, to some extent, on cereals does not fully cover the demands of other agricultural plants of temperate climate, including forage grasses. Two Lolium perenne (perennial ryegrass) genotypes with contrasting levels of frost tolerance, the high frost tolerant (HFT) and the low frost tolerant (LFT) genotypes, were selected for comparative metabolomic research. The work focused on the analysis of leaf metabolite accumulation before and after seven separate time points of cold acclimation. Gas chromatography-mass spectrometry (GC/MS) was used to identify amino acids (alanine, proline, glycine, glutamic and aspartic acid, serine, lysine and asparagine), carbohydrates (fructose, glucose, sucrose, raffinose and trehalose) and their derivatives (mannitol, sorbitol and inositol) accumulated in leaves in low temperature. The observed differences in the level of frost tolerance between the analysed genotypes could be partially due to the time point of cold acclimation at which the accumulation level of crucial metabolite started to increase. In the HFT genotype, earlier accumulation was observed for proline and asparagine. The increased amounts of alanine, glutamic and aspartic acids, and asparagine during cold acclimation could be involved in the regulation of photosynthesis intensity in L. perenne. Among the analysed carbohydrates, only raffinose revealed a significant association with the acclimation process in this species.

Experimental studies of the argon-puff Z-pinch implosion process

International Nuclear Information System (INIS)

Huang Xianbin; Yang Libing; Gu Yuanchao; Deng Jianjun; Zhou Rongguo; Zou Jie; Zhou Shaotong; Zhang Siqun; Chen Guanghua; Chang Lihua; Li Fengping; Ouyang Kai; Li Jun; Yang Liang; Wang Xiong; Zhang Zhaohui

2006-01-01

A preliminary experiment for studying the argon-puff Z-pinch implosion process has been performed on the Yang accelerator. The ten-frame nanosecond temporal and spatial gated camera, visible high-speed scanning camera, differential laser interferometer, X-ray time integration pinhole camera and X-ray power system have been used to investigated the evolution of the argon-puff Z-pinch. Some typical results of argon-puff Z-pinch during implosion and pinch phase, including the 'zipper' effect, necking phenomenon, sausage instability, temperature changes and the effect of load current rise time, are given and analyzed as examples, and some relevant conclusions are drawn. (authors)

An Experimental Investigation On Minimum Compressive Strength Of Early Age Concrete To Prevent Frost Damage For Nuclear Power Plant Structures In Cold Climates

International Nuclear Information System (INIS)

Koh, Kyungtaek; Kim, Dogyeum; Park, Chunjin; Ryu, Gumsung; Park, Jungjun; Lee, Janghwa

2013-01-01

Concrete undergoing early frost damage in cold weather will experience significant loss of not only strength, but also of permeability and durability. Accordingly, concrete codes like ACI-306R prescribe a minimum compressive strength and duration of curing to prevent frost damage at an early age and secure the quality of concrete. Such minimum compressive strength and duration of curing are mostly defined based on the strength development of concrete. However, concrete subjected to frost damage at early age may not show a consistent relationship between its strength and durability. Especially, since durability of concrete is of utmost importance in nuclear power plant structures, this relationship should be imperatively clarified. Therefore, this study verifies the feasibility of the minimum compressive strength specified in the codes like ACI-306R by evaluating the strength development and the durability preventing the frost damage of early age concrete for nuclear power plant. The results indicate that the value of 5 MPa specified by the concrete standards like ACI-306R as the minimum compressive strength to prevent the early frost damage is reasonable in terms of the strength development, but seems to be inappropriate in the viewpoint of the resistance to chloride ion penetration and freeze-thaw. Consequently, it is recommended to propose a minimum compressive strength preventing early frost damage in terms of not only the strength development, but also in terms of the durability to secure the quality of concrete for nuclear power plants in cold climates

An Experimental Investigation On Minimum Compressive Strength Of Early Age Concrete To Prevent Frost Damage For Nuclear Power Plant Structures In Cold Climates

Energy Technology Data Exchange (ETDEWEB)

Koh, Kyungtaek; Kim, Dogyeum; Park, Chunjin; Ryu, Gumsung; Park, Jungjun; Lee, Janghwa [Korea Institute Construction Technology, Goyang (Korea, Republic of)

2013-06-15

Concrete undergoing early frost damage in cold weather will experience significant loss of not only strength, but also of permeability and durability. Accordingly, concrete codes like ACI-306R prescribe a minimum compressive strength and duration of curing to prevent frost damage at an early age and secure the quality of concrete. Such minimum compressive strength and duration of curing are mostly defined based on the strength development of concrete. However, concrete subjected to frost damage at early age may not show a consistent relationship between its strength and durability. Especially, since durability of concrete is of utmost importance in nuclear power plant structures, this relationship should be imperatively clarified. Therefore, this study verifies the feasibility of the minimum compressive strength specified in the codes like ACI-306R by evaluating the strength development and the durability preventing the frost damage of early age concrete for nuclear power plant. The results indicate that the value of 5 MPa specified by the concrete standards like ACI-306R as the minimum compressive strength to prevent the early frost damage is reasonable in terms of the strength development, but seems to be inappropriate in the viewpoint of the resistance to chloride ion penetration and freeze-thaw. Consequently, it is recommended to propose a minimum compressive strength preventing early frost damage in terms of not only the strength development, but also in terms of the durability to secure the quality of concrete for nuclear power plants in cold climates.

Argon laser phototherapy of human malignancies using rhodamine-123 as a new laser dye: The intracellular role of oxygen

International Nuclear Information System (INIS)

Castro, D.J.; Saxton, R.E.; Markley, J.; Foote, C.S.; Fetterman, H.R.; Castro, D.J.; Ward, P.H.

1990-01-01

Recent studies demonstrated that the cationic, mitochondrial-specific dye Rhodamine-123 (Rh-123), is an efficient tumor photosensitizer for Argon laser treatment of human cancer cells both in vitro and in tumors grown as xenografts in athymic mice. To demonstrate the photodynamic mechanism of action of this reaction, the intracellular role of oxygen and temperature changes in treated cells have to be defined. In the current study, a large panel of human tumor cell lines of diverse histologic origin were tested for in vitro sensitivity to Rh-123 and the Argon laser (514.5 nm) in oxygen, deuterium oxide (D2O), and nitrogen (N2) environment. Tumor cells in suspension were first sensitized to Rh-123 (1 or 20 micrograms/ml for 1 hour), cooled on ice to 4 degrees C, and then exposed to the Argon laser (delta T = 14 +/- 1 degree C). Cell proliferation measured by [3H]-thymidine uptake 24 hours after sensitization with Rh-123 and laser treatment was significantly decreased in tumor cells kept in oxygen and D2O atmospheres. No decrease in DNA synthesis was seen in Rh-123 and laser treated cells kept in an N2 environment. Control tumor cells treated with Rh-123 or the Argon laser separately did not show any decreased [3H]-thymidine uptake in oxygen, D2O or N2 environment. These results provide evidence of a photodynamic process since Rh-123 sensitization and Argon laser activation occur at nonthermal levels of energy and are oxygen dependent. The high effectiveness of this technique of photodynamic therapy with the Argon laser, and low toxicity of Rh-123 could make its clinical use very attractive for the treatment of superficial malignancies

Ionizing Shocks in Argon. Part 2: Transient and Multi-Dimensional Effects (Preprint)

Science.gov (United States)

2010-09-09

stability in ionizing monatomic gases. Part 1. Argon ,” J. Fluid Mech., 84, 55 (1978). 2M. P. F. Bristow and I. I. Glass, “ Polarizability of singly...Article 3. DATES COVERED (From - To) 4. TITLE AND SUBTITLE 5a. CONTRACT NUMBER Ionizing Shocks in Argon . Part 2: Transient...Physics. 14. ABSTRACT We extend the computations of ionizing shocks in argon to unsteady and multi-dimensional, using a collisional-radiative

Sodium evaporation into a forced argon flow, (1)

International Nuclear Information System (INIS)

Kumada, Toshiaki; Kasahara, Fumio; Ishiguro, Ryoji

1976-01-01

Measurements were made on the rate of evaporation from a rectangular-shaped free surface of liquid sodium into argon flow. Tests were carried out at various levels of sodium temperature, of argon velocity and of argon temperature, under conditions where fog formation could be expected. To gain information on the enhancement of evaporation occasioned by fog formation, a supplementary experiment was performed on convection heat transfer into flowing air from a heated plate of the same geometry as the free surface of the sodium in the preceding measurements. The values obtained for the rate of evaporation and Sherwood number were compared with those predicted by the heat transfer experiment and by the theory by Hill and Szekely. The overall results revealed that the rate of sodium evaporation can amount to as much as three times that predicted by the heat transfer experiment, and that it varies roughly linearly with the heat transfer rate and with the sodium vapor pressure prevailing at the free surface. (auth.)

Frosted Branch Angiitis Diagnosed as Neuro-Behçet: A Diagnostic and Etiologic Dilemma

Directory of Open Access Journals (Sweden)

Alejandro Portero

2011-05-01

Full Text Available Purpose: To report a case of frosted branch angiitis (FBA secondary to neuro-Behçet. Methods: Description, diagnosis, angiogram imaging and follow-up of a 28-year-old female with FBA. Results: ‘Frosted branch angiitis’ is a clinical term applied to three conditions: infiltration of vessels by malignant cells, and sheathing of vessels either secondary to an active disorder or subsequently to a previous inflammatory disease. Our patient’s history of two optic neuropathies and the lack of demyelinating signs in neuroimaging made us consider FBA in the context of neuro-Behçet. Conclusion: Recognition of the category of FBA from the clinical signs is essential to establish the correct diagnosis and prescribe the appropriate treatment.

Bacterial stem blight of alfalfa: A disease that increases frost damage

Science.gov (United States)

Alfalfa producers count on the first harvest in late spring to deliver the highest tonnage and best quality of forage of the year. A late frost can significantly reduce both yield and quality. Losses are due not only to the physical damage from freezing of the alfalfa stem and leaves but also from d...

Inter population variability of frost-resistance in provenances of scot pines (Pinusylvestris L.R. hamata Steven in Turkey

Directory of Open Access Journals (Sweden)

Özel Halil Barış

2016-01-01

Full Text Available Frost-resistance variability of Scotch pine (Pinus sylvestris L. var. hamata Steven seedlings grown in nurseries conditions, originated from 10 provenances, have been analyzed. The provenances from Black Sea region, Central Anatolian region and Eastern Anatolian region in Turkey have been used in selection of seed zones. The results of frost-resistance tests indicated a strong relationship of implemented freezing degrees with injury degrees of Scotch pine needles and photosynthetic productivities. On the other hand, another significant relationship has been determined between chlorophyll fluorescence and ion leakage methods (r=-0.801. This result shows that those two methods can be safely used in determining the damages due to low temperatures. In frost resistance tests, Scotch pine seedlings from different provenances have been frozen at -10, -20, -30 and -40°C. According to the Duncan test results, it has been determined that damage increased as temperature decreased. The damage level at -10°C implementation is 3.5% which can be tolerated by plants. But when the temperature has been decreased to -20°C, the level of damage has increased to 51.25%. As a result of photosynthetic analyses in this phase, it has been determined that there is a statistically significant relationship between provenances and temperature levels. Under the light of those findings, they have determined that the photosynthetic productivity has significantly decreased at temperatures between -20°C and -40°C. This situation conforms to injury index values determined in this study. As a result of injury index and photosynthetic productivity tests used for determining the damage after frost-resistance tests, it has been determined that the provenances of Amasya-Kunduz, Bolu-Aladağ, Düzce-Yığılca, Samsun-Vezirköprü and Eskişehir-Çatacık are more sensitive to frost than other provenances.

Copy number and haplotype variation at the VRN-A1 and central FR-A2 loci are associated with frost tolerance in hexaploid wheat.

Science.gov (United States)

Zhu, Jie; Pearce, Stephen; Burke, Adrienne; See, Deven Robert; Skinner, Daniel Z; Dubcovsky, Jorge; Garland-Campbell, Kimberly

2014-05-01

The interaction between VRN - A1 and FR - A2 largely affect the frost tolerance of hexaploid wheat. Frost tolerance is critical for wheat survival during cold winters. Natural variation for this trait is mainly associated with allelic differences at the VERNALIZATION 1 (VRN1) and FROST RESISTANCE 2 (FR2) loci. VRN1 regulates the transition between vegetative and reproductive stages and FR2, a locus including several tandemly duplicated C-REPEAT BINDING FACTOR (CBF) transcription factors, regulates the expression of Cold-regulated genes. We identified sequence and copy number variation at these two loci among winter and spring wheat varieties and characterized their association with frost tolerance. We identified two FR-A2 haplotypes-'FR-A2-S' and 'FR-A2-T'-distinguished by two insertion/deletions and ten single nucleotide polymorphisms within the CBF-A12 and CBF-A15 genes. Increased copy number of CBF-A14 was frequently associated with the FR-A2-T haplotype and with higher CBF14 transcript levels in response to cold. Factorial ANOVAs revealed significant interactions between VRN1 and FR-A2 for frost tolerance in both winter and spring panels suggesting a crosstalk between vernalization and cold acclimation pathways. The model including these two loci and their interaction explained 32.0 and 20.7 % of the variation in frost tolerance in the winter and spring panels, respectively. The interaction was validated in a winter wheat F 4:5 population segregating for both genes. Increased VRN-A1 copy number was associated with improved frost tolerance among varieties carrying the FR-A2-T allele but not among those carrying the FR-A2-S allele. These results suggest that selection of varieties carrying the FR-A2-T allele and three copies of the recessive vrn-A1 allele would be a good strategy to improve frost tolerance in wheat.

Addition of photosensitive dopants to the D0 liquid argon calorimeter

International Nuclear Information System (INIS)

Amos, N.A.; Anderson, D.F.

1992-10-01

The addition of photosensitive dopants to liquid argon greatly enhances the signal from heavily ionizing particles. Since binding energy losses we correlated with the heavily ionizing component in hadronic showers, the addition of photosensitive dopants has been suggested as a mechanism to tune the e/π ratio in liquid argon calorimeters. A measurement was performed at the FNAL test beam, adding 4 ppM tetramethylgermanium to the Dφ uranium-liquid argon calorimeter. An increase in response for electromagnetic and hadronic showers was observed, with no net change in the e/π ratio

Commissioning and Charge Readout Calibration of a 5 Ton Dual Phase Liquid Argon TPC

CERN Document Server

AUTHOR|(CDS)2098555

Dual phase time projection chambers with amplification of ionization electrons provide a novel technique for measuring and analyzing rare events with excellent spatial resolution and great calorimetric properties. This thesis describes the commissioning of the WA105 3 x 1 x 1 m3 dual phase liquid argon detector, built to demonstrate the performance of this kind of detector on large scales in order to determine the viability of giant dual phase time projection chambers in long baseline neutrino oscillation experiments. The properties of the insulation and the main tank vessel are described and analyzed, such as the pressure, temperature and argon purity requirements during operation in order to guarantee stable conditions and good event tracking. As signals are induced due to electrons from ionizing radiation, crosstalk is caused by capacitive couplings between strips of the charge readout plane and in the electronics of the data acquisition. These induced signals are studied and compared to capacitance and pu...

The ICARUS Front-end Preamplifier Working at Liquid Argon Temperature

CERN Document Server

Baibussinov, B; Casagrande, F; Cennini, P; Centro, S; Curioni, A; Meng, G; Picchi, P; Pietropaolo, F; Rubbia, C; Sergiampietri, F; Ventura, S

2011-01-01

We describe characteristics and performance of the low-noise front-end preamplifier used in the ICARUS 50-litre liquid Argon Time Projection Chamber installed in the CERN West Area Neutrino Facility during the 1997-98 neutrino runs. The preamplifiers were designed to work immersed in ultra-pure liquid Argon at a temperature of 87K.

Comparison study of nitrogen and argon processing in a plasma arc centrifugal treatment system

International Nuclear Information System (INIS)

Shuey, M.; Tsuji, Y.

2000-01-01

Recent testing performed at the plasma research center of Retech Services, Inc. compared nitrogen with argon as plasma gas in the processing of simulated wastes. The testing took place in a full-scale production PACT system under a cooperative research and development study between Retech Services Inc. and Toyo Engineering Corporation. This study shows that simulated waste can be processed by both nitrogen and argon plasmas. Heat losses to the torch nozzle were significantly lower with argon and should be studied further. Both argon and nitrogen plasma were able to process feeds containing both metals and oxides. Some of the drawbacks to using argon plasma are cost, higher volume flow rates, and dual mode torch nozzle erosion. (authors)

Evolution of subsurface nanocavities in copper under argon bombardment and annealing

NARCIS (Netherlands)

Kulikov, D.V.; Kurnosikov, O.; Kharlamov, V.S.; Trushin, Yu.V.

2013-01-01

The experimental and theoretical studies of evolution of nanocavities in argon-irradiated copper under annealing are presented. The subsurface argon-filled nanocavities are formed during a short annealing at a temperature around 1000 K by migration and interaction of complexes of the simplest

Alphas and surface backgrounds in liquid argon dark matter detectors

Science.gov (United States)

Stanford, Christopher J.

Current observations from astrophysics indicate the presence of dark matter, an invisible form of matter that makes up a large part of the mass of the universe. One of the leading theories for dark matter is that it is made up of Weakly Interacting Massive Particles (WIMPs). One of the ways we try to discover WIMPs is by directly detecting their interaction with regular matter. This can be done using a scintillator such as liquid argon, which gives off light when a particle interacts with it. Liquid argon (LAr) is a favorable means of detecting WIMPs because it has an inherent property that enables a technique called pulse-shape discrimination (PSD). PSD can distinguish a WIMP signal from the constant background of electromagnetic signals from other sources, like gamma rays. However, there are other background signals that PSD is not as capable of rejecting, such as those caused by alpha decays on the interior surfaces of the detector. Radioactive elements that undergo alpha decay are introduced to detector surfaces during construction by radon gas that is naturally present in the air, as well as other means. When these surface isotopes undergo alpha decay, they can produce WIMP-like signals in the detector. We present here two LAr experiments. The first (RaDOSE) discovered a property of an organic compound that led to a technique for rejecting surface alpha decays in LAr detectors with high efficiency. The second (DarkSide-50) is a dark matter experiment operated at LNGS in Italy and is the work of an international collaboration. A detailed look is given into alpha decays and surface backgrounds present in the detector, and projections are made of alpha-related backgrounds for 500 live days of data. The technique developed with RaDOSE is applied to DarkSide-50 to determine its effectiveness in practice. It is projected to suppress the surface background in DarkSide-50 by more than a factor of 1000.

Frost for the trees: Did climate increase erosion in unglaciated landscapes during the late Pleistocene?

Science.gov (United States)

Marshall, Jill A; Roering, Joshua J; Bartlein, Patrick J; Gavin, Daniel G; Granger, Darryl E; Rempel, Alan W; Praskievicz, Sarah J; Hales, Tristram C

2015-11-01

Understanding climatic influences on the rates and mechanisms of landscape erosion is an unresolved problem in Earth science that is important for quantifying soil formation rates, sediment and solute fluxes to oceans, and atmospheric CO2 regulation by silicate weathering. Glaciated landscapes record the erosional legacy of glacial intervals through moraine deposits and U-shaped valleys, whereas more widespread unglaciated hillslopes and rivers lack obvious climate signatures, hampering mechanistic theory for how climate sets fluxes and form. Today, periglacial processes in high-elevation settings promote vigorous bedrock-to-regolith conversion and regolith transport, but the extent to which frost processes shaped vast swaths of low- to moderate-elevation terrain during past climate regimes is not well established. By combining a mechanistic frost weathering model with a regional Last Glacial Maximum (LGM) climate reconstruction derived from a paleo-Earth System Model, paleovegetation data, and a paleoerosion archive, we propose that frost-driven sediment production was pervasive during the LGM in our unglaciated Pacific Northwest study site, coincident with a 2.5 times increase in erosion relative to modern rates. Our findings provide a novel framework to quantify how climate modulates sediment production over glacial-interglacial cycles in mid-latitude unglaciated terrain.

Effects of introduction of argon on structural and transparent conducting properties of ZnO-In2O3 thin films prepared by pulsed laser deposition

International Nuclear Information System (INIS)

Moriga, Toshihiro; Mikawa, Michio; Sakakibara, Yuji; Misaki, Yukinori; Murai, Kei-ichiro; Nakabayashi, Ichiro; Tominaga, Kikuo; Metson, James B.

2005-01-01

Indium-zinc oxide thin films were deposited on a glass substrate from a ZnO and In 2 O 3 mixed target by a pulsed laser deposition technique. The effects on surface texture, structure and transparent conducting properties of the introduction of argon into the chamber during the depositions of amorphous and homologous ZnO-In 2 O 3 thin films were examined. The compositional range where amorphous films formed was widened by the introduction of argon. Resistivity in the region where the amorphous phase appeared increased slightly, with an increase of zinc content, due to the counteractions of decreased Hall mobility and increased carrier concentration. Introduction of argon improved surface roughness of the films and reduced and regulated particle and/or crystallite sizes of the films

Agricultural losses related to frost events: use of the 850 hPa level temperature as an explanatory variable of the damage cost