Journal articles: 'Helium tank'

1

Popov, O. M., F. V. Ustenko, V. G. Tyles, and N. V. Markelova. "Improved 500-liter transport tank for liquid helium." Chemical and Petroleum Engineering 28, no. 9 (September 1992): 551–54. http://dx.doi.org/10.1007/bf01150577.

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Park, Youn Mi, Seh Wan In, and Sang Kwon Jeong. "The Size Optimization of the Liquid Helium Pressurant Tank for Liquid Propellant Rocket." Key Engineering Materials 277-279 (January 2005): 776–82. http://dx.doi.org/10.4028/www.scientific.net/kem.277-279.776.

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An efficient and reliable pressurization system for an oxidizer and fuel of a liquid propellant rocket is critical for a successful launch. A liquid helium pressurization system employing a heater can reduce its mass, and be made simpler and more reliable than conventional pressurization systems. The key issue to minimize the total mass of the system is the optimization of the size of the liquid helium tank. In this paper, we describe a method to determine the optimal size of a liquid helium tank, and present one set of results under a given set of requirements. In this pressurization system, the heater design is represented by the heater efficiency. To estimate the heater efficiency, the convection heat transfer coefficient should be known beforehand. The guideline how to estimate this convection heat transfer coefficient based on the preliminary experimental data is also presented in this paper.

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Fujiyoshi, Yoshinori. "High-Resolution Cryo-Electron Microscopy of Biological Macromolecules." Proceedings, annual meeting, Electron Microscopy Society of America 48, no. 1 (August 12, 1990): 126–27. http://dx.doi.org/10.1017/s0424820100179385.

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The resolution of direct images of biological macromolecules is normally restricted to far less than 0.3 nm. This is not due instrumental resolution, but irradiation damage. The damage to biological macromolecules may expect to be reduced when they are cooled to a very low temperature. We started to develop a new cryo-stage for a high resolution electron microscopy in 1983, and successfully constructed a superfluid helium stage for a 400 kV microscope by 1986, whereby chlorinated copper-phthalocyanine could be photographed to a resolution of 0.26 nm at a stage temperature of 1.5 K. We are continuing to develop the cryo-microscope and have developed a cryo-microscope equipped with a superfluid helium stage and new cryo-transfer device.The New cryo-microscope achieves not only improved resolution but also increased operational ease. The construction of the new super-fluid helium stage is shown in Fig. 1, where the cross sectional structure is shown parallel to an electron beam path. The capacities of LN2 tank, LHe tank and the pot are 1400 ml, 1200 ml and 3 ml, respectively. Their surfaces are placed with gold to minimize thermal radiation. Consumption rates of liquid nitrogen and liquid helium are 170 ml/hour and 140 ml/hour, respectively. The working time of this stage is more than 7 hours starting from full LN2 and LHe tanks. Instrumental resolution of our cryo-stage cooled to 4.2 K was confirmed to be 0.20 nm by an optical diffraction pattern from the image of a chlorinated copper-phthalocyanine crystal. The image and the optical diffraction pattern are shown in Fig. 2 a, b, respectively.

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Sudadiyo, Sri, and Geni Rina Sunaryo. "THERMODYNAMICS ANALYSES ON REGENERATIVE STEAM CYCLE WITH TWO TANKS FOR HTGR-10 CONCEPT." GANENDRA Majalah IPTEK Nuklir 20, no. 2 (September 15, 2017): 73. http://dx.doi.org/10.17146/gnd.2017.20.2.3302.

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THERMODYNAMICS ANALYSES ON REGENERATIVE STEAM CYCLE WITH TWO TANKS FOR HTGR-10 CONCEPT. In this work, steam cycle from a nuclear power plant is explored in order to increase electric power efficiency and output. A thermal source in the form of a HTGR-10 concept is considered. The power conversion unit of HTGR-10 consists of steam generators, turbines, condensers, pumps , and connecting pipes. Helium is used as the core coolant and the working fluid for power conversion unit is water/steam. The proposed thermodynamic process modification has been evaluated for regenerative steam power cycle of this reactor. The scope of study covered regenerative steam cycle with two tanks including feed water tank and intermediate feed water tank. The evaluation analyzes the effect of pressure, efficiencies of turbine and pumps, and tanks against thermal efficiency. The Cycle-Tempo software is used to simulate and optimize those effects on steam cycle based on HTGR-10. The results indicate improvements of as much as 2.65 % in thermal efficiency and 0.271 MWe in electric power.

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Wang, Lei, Shixuan Ye, Yuan Ma, Jiaojiao Wang, and Yanzhong Li. "CFD investigation on helium pressurization behaviors in liquid hydrogen tank." International Journal of Hydrogen Energy 42, no. 52 (December 2017): 30792–803. http://dx.doi.org/10.1016/j.ijhydene.2017.10.145.

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Kwon, Ohsung, Byunghun Kim, Gyoungsub Kil, Inhyun Cho, and Youngsung Ko. "Modeling the Prediction of Helium Mass Requirement for Propellant Tank Pressurization." Journal of Spacecraft and Rockets 49, no. 6 (November 2012): 1150–58. http://dx.doi.org/10.2514/1.a32073.

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7

Zhang, Caigong, Changjun Li, Wenlong Jia, and Yu Pang. "Thermodynamic study on thermal insulation schemes for liquid helium storage tank." Applied Thermal Engineering 195 (August 2021): 117185. http://dx.doi.org/10.1016/j.applthermaleng.2021.117185.

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8

Zhu, Ming, Gao Feng Xie, and Rong Shun Wang. "Experimental Investigation of the Influence of the Gas Type on the Heat Transfer in a High-Vacuum-Multilayer-Insulation Cryogenic Tank After Sudden, Catastrophic Loss of Insulating Vacuum." Advanced Materials Research 354-355 (October 2011): 294–303. http://dx.doi.org/10.4028/www.scientific.net/amr.354-355.294.

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One of the worst accidents that may occur in a high-vacuum-multilayer-insulation (HVMLI) cryogenic tank is a sudden, catastrophic loss of insulation vacuum (SCLIV). it is obvious that the different gas leaking into the insulation jacket have some influence on the heat transfer process. However, this problem has not been studied systematically so far. In this paper, a test rig was built up and experiments were conducted on a SCLIV cryogenic tank by using the nitrogen, helium, oxygen, carbon dioxide and air as the leaking medium, respectively. Some important phenomena and heat transfer characteristics in a vacuum-lost HVMLI cryogenic tank have been obtained. The effects of the insulation layer numbers and the type of gases on venting rate and heat flux into the cryogenic liquid have been measured, analyzed and discussed. It indicates that the heat transfer performance of the HVMLI cryogenic tank after SCLIV is strong related to the type of gases leaking into the insulation jacket.

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9

PUTCHA, CHANDRA S., PRINCE KALIA, FRANK PIZZANO, GORDON HOSKINS, COY NEWTON, and KUNAL J. KAMDAR. "A CASE STUDY ON FMEA APPLICATIONS TO SYSTEM RELIABILITY STUDIES." International Journal of Reliability, Quality and Safety Engineering 15, no. 02 (April 2008): 159–66. http://dx.doi.org/10.1142/s0218539308003003.

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Failure Mode and Effect Analysis (FMEA) has been used quite extensively in aerospace industry for several years to establish hardware criticality. Determination of software reliability is equally important. There are several methods for determining software reliability. One methods for performing software reliability is the software FMEA. This paper discusses the application of principles to FMEA. A typical Tank pressurant is considered as an illustrative example. The tank pressurant system consists of three sets of solenoid valves (each set consists of a pair of valves), three pressure transducers, a vent valve, a heat exchanger and helium cold pressure bottles. Each set of solenoid valves consist of two solenoid valves connected in series. For the system to function properly, certain conditions have to be met. These are discussed in detail later in this paper. Based on the information provided from NASA, it is concluded that FMEA has to be capable of determining the software failure modes, effects and criticality as well as the hardware failure modes effects and criticality which includes the pressure transducers, solenoid valves, vent valve, heat exchanger and helium cold pressure bottles. The paper will discuss both the hardware and software FMEA application in detail.

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10

Chorowski, M., M. Grabowski, A. Jędrusyna, and J. Wach. "Modelling and Experimental Verification of Pressure Wave Following Gaseous Helium Storage Tank Rupture." Physics Procedia 67 (2015): 1083–88. http://dx.doi.org/10.1016/j.phpro.2015.06.204.

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11

Zhang, Chuanjia, Qiyong Zhang, Zhigang Zhu, Damao Yao, Pengcheng Yang, Yiwen Zong, and Shixiong Chen. "Numerical simulation of thermal–structural behaviour of liquid helium tank during filling process." Fusion Engineering and Design 173 (December 2021): 112798. http://dx.doi.org/10.1016/j.fusengdes.2021.112798.

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12

Митиков, Юрий Алексеевич, Наталия Михайловна Соловьева, and Богдана Александровна Крысько. "АММИАЧНЫЕ СИСТЕМЫ НАДДУВА ТОПЛИВНЫХ БАКОВ ДВИГАТЕЛЬНЫХ УСТАНОВОК РАКЕТ-НОСИТЕЛЕЙ." Aerospace technic and technology, no. 1 (February 25, 2018): 37–42. http://dx.doi.org/10.32620/aktt.2018.1.03.

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Fuel tank pressurization systems are some of most science-intensive and expensive parts of rocket carriers. There is a lot of interest in usage of structurally simple pressurization systems, including those, which don't use working bodies from the start, such as gas-generating and chemical. The possibilities of using liquid ammonia in fuel-boost systems tanks as a working fluid had been researched. The analysis of earlier and modern systems of pressurization of tanks oxidant and hot carrier rockets whose propulsion systems use liquid oxygen and kerosene had been analysed with examination of advantages and drawbacks. The purpose of conducted research is finding effective modes and simplific design of fuel tank pressurization systems with kerosene while using as working pressure of liquid ammonia. It has long been successfully used in missile technology in stabilization systems of space vehicles. The operational characteristics of ammonia and thermal aspects of its decomposition into hydrogen and nitrogen. The rate of decomposition of ammonia satisfies requirements pressurization. The gas constant of ammonia decomposition products is 978, 2 kJ. The notable disadvantage of this working body of pressurization with respect to the pressurization systems is a large the amount of heat necessary for its decomposition. The positive role of catalysts (iron, tungsten, ruthenium). Audited thermal energy on board the launch vehicle. There are offered schemes, using the heat of the engine's torch and the heat of the solid-fuel gas generator. Recommended azide gas generators, which generate pure high-temperature nitrogen. Such a scheme increases the possibility of being pressurized with helium. The possibilities of using decomposition products ammonia to pressurize the tank with oxidizer. The high efficiency of ammonia pressurizing systems example of the first stage of the medium-sized launch vehicle

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13

Cao, Jianzhu, Liguo Zhang, Feng Xie, Bing Xia, and Stephen Tsz Tang Lam. "Source Term Study on Tritium in HTR-PM: Theoretical Calculations and Experimental Design." Science and Technology of Nuclear Installations 2017 (2017): 1–11. http://dx.doi.org/10.1155/2017/3586723.

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The high temperature gas-cooled reactor pebble-bed module (HTR-PM) in China received much attention for its inherent safety performance and high thermal efficiency. The generation mechanism, distribution, reduction route, and release type of tritium (H-3) in HTR-PM are presented with a complete theoretical model. The calculation results indicate the majority of H-3 in the core is generated by the activation reaction of B-10. The activity concentration of H-3 in the primary loop and the specific activity of H-3 in the secondary loop at the operating equilibrium are computed as 3.69 × 106 Bq/m3STPof helium and 4.22 × 104 Bq/kg of water, respectively. The H-3 sampling measurement in HTR-PM has been designed to collect data from the primary coolant, from the liquid waste storage tank, from the secondary coolant, and from the liquid and gaseous effluents, separately. In this paper, the design of H-3 sampling positions in the helium purification system is discussed. The H-3 sampling measurement from the primary helium in HTR-PM has been improved, which can provide reliable activity concentration data of H-3 in the primary loop and supply accurate evaluation for the efficiency of the helium purification system.

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14

Cho, Gyu-Sik, Young-Suk Jung, and Seung-Hyub Oh. "Helium Quantity Estimation for LOx Tank Pressurization of a Restartable Pressure-fed Propulsion System." Journal of the Korean Society of Propulsion Engineers 16, no. 3 (June 1, 2012): 77–81. http://dx.doi.org/10.6108/kspe.2012.16.3.077.

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15

Richardson, I. A., and J. W. Leachman. "Modeling the effects of dissolved helium pressurant on a liquid hydrogen rocket propellant tank." IOP Conference Series: Materials Science and Engineering 278 (December 2017): 012037. http://dx.doi.org/10.1088/1757-899x/278/1/012037.

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16

Lei, Wang, Li Yanzhong, Jin Yonghua, and Ma Yuan. "Experimental investigation on pressurization performance of cryogenic tank during high-temperature helium pressurization process." Cryogenics 66 (March 2015): 43–52. http://dx.doi.org/10.1016/j.cryogenics.2014.12.001.

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17

Liu, Zhan, Jie Cui, Jia Yan, Guoqing Zhou, and Yanzhong Li. "Effect of initial parameter on thermodynamic performance in a liquid oxygen tank with pressurized helium gas." Science and Technology for the Built Environment 26, no. 3 (July 15, 2019): 426–36. http://dx.doi.org/10.1080/23744731.2019.1624096.

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18

Wang, Lei, Yanzhong Li, Zhixiang Zhao, and Zhan Liu. "Transient thermal and pressurization performance of LO2 tank during helium pressurization combined with outside aerodynamic heating." International Journal of Heat and Mass Transfer 62 (July 2013): 263–71. http://dx.doi.org/10.1016/j.ijheatmasstransfer.2013.03.021.

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19

De Salve, M., D. Milani, B. Panella, and G. Roveta. "A Laboratory Plant for Gas Liquefaction." International Journal of Air-Conditioning and Refrigeration 23, no. 02 (May 27, 2015): 1550010. http://dx.doi.org/10.1142/s2010132515500108.

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A prototype gas liquefaction plant has been designed and manufactured for Politecnico di Torino cryogenic laboratory and has been used for cryogenic applications like superconducting cables and low temperature refrigeration devices. The plant is able to liquefy nitrogen and, by means of little changes, hydrogen and other cryogenic fluids too. The thermal energy is removed by four high speed (up to 360 000 revolutions per minute) helium turbines that are connected in series. The gas liquefaction is carried out by the cooling condensation process of the gas flow that feeds a 0.15 m3 super insulated tank that is cooled inside. The cryogenic system is based on the Claude and Collins cycles, fed with helium that provides the cold sink. The paper shows the characteristics of the plant main components, and the time history of the measured temperatures, pressures, and flow rates during the plant start-up, as well as the steady state liquefied gas production rate. From the energetic point of view, the plant performance is acceptable for a research laboratory and the plant efficiency is not far from that of commercial larger size plants.

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20

Ebuehi, Osaretin N. I., Kingsley Abhulimen, and Daniel O. Adebesin. "Modelling Production of Renewable Energy from Water Splitting High Thermal Electrolysis Processes." European Journal of Engineering and Technology Research 6, no. 3 (April 12, 2021): 14–21. http://dx.doi.org/10.24018/ejers.2021.6.3.2391.

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Recently, fuel gas from water has become the center of attention because it is a renewable source of energy and eco-friendly. In this study, the hydrogen gas simulated was obtained from the high-temperature water splitting electrolysis model, because it is more efficient than the low-temperature water splitting electrolysis process. It also releases oxygen as a byproduct. The high-temperature electrolysis model is made up of three loops: primary high-temperature helium loop, secondary helium loop, and high-temperature electrolysis loop. Hydrogen gave a temperature of 27.20C, a pressure of 49.5 bars, and a molar flow of 84.02MMSCFD. The hydrogen gas from a high-temperature electrolysis model is simulated with a CO2 gas stream to produce methane and water, also releasing unreacted carbon dioxide and hydrogen. Key parameters such as molar entropy, molar enthalpy, heat flow, and cost flow were evaluated by Aspen HYSYS V8.8. The simulation model used for this work is the Sabatier Process Model. In this model, Continuous stirred tank, Converter, Equilibrium, Gibbs, Plug flow reactors were used to generate methane. The Converter reactor gave the highest yield of methane gas with a mole fraction of 0.2390. Key benchmarks, including temperature, heat flow, cost flow, cost factor were varied to see how they can affect methane gas and other products.

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Andris, Andreas, Felix Fischer, Marion Herrmann, Wolfgang Lippmann, and Antonio Hurtado. "Investigations of Graphite Particle Interaction with Metallic Surfaces." Metals 10, no. 1 (January 16, 2020): 140. http://dx.doi.org/10.3390/met10010140.

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Previous studies on the safety of gas-cooled high-temperature reactors (HTR) have analyzed the corrosion and oxidation behavior of the primary circuit components under normal and accident conditions. Through the use of graphite components, graphite particles can be formed by mechanical and chemical means whose influence on the structural change of metal surfaces must be analyzed in a comprehensive manner. The dust resuspension and deposition in tank geometry (DRESDEN-TANK) test facility was set up to thermally anneal metallic samples (Alloy 800H, Inconel 617) loaded with graphite particles under typical HTR conditions (helium, 750 °C, 6 MPa) for the investigation of interactions over a long-term range. In addition to the carrying out of a description of the processes occurring on the material surface, the gaseous reaction products have been analyzed. The results show that the presence of graphite particles in the near-surface layer has a significant impact on corrosion processes due to thermally-induced interactions. In this case iron and chromium are degraded in the metallic alloys, which leads to a structural change in the near-surface layer. Furthermore, the graphite particles significantly influence the formation of the oxide layers on the alloys; for example, they influence the formation speed of the layer and the layer height. The originally deposited particles thus exhibit a chemically-altered composition and a different geometric shape.

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22

Lei, Wang, Li Yanzhong, Liu Zhan, and Zhu Kang. "Numerical Investigation of Thermal Distribution and Pressurization Behavior in Helium Pressurized Cryogenic Tank by Introducing a Multi-component Model." Physics Procedia 67 (2015): 392–97. http://dx.doi.org/10.1016/j.phpro.2015.06.047.

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23

Kim, K. H., H. J. Ko, K. Kim, Y. S. Jung, S. H. Oh, and K. J. Cho. "Transient thermal analysis of a cryogenic oxidizer tank in the liquid rocket propulsion system during the prelaunch helium gas pressurization." Journal of Engineering Thermophysics 21, no. 1 (February 25, 2012): 1–15. http://dx.doi.org/10.1134/s1810232812010018.

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24

Moses, G. A., G. L. Kulcinski, D. Bruggink, R. Engelstad, E. Lovell, J. Macfarlane, Z. Musicki, et al. "LIBRA–A light ion beam inertial confinement fusion reactor conceptual design." Laser and Particle Beams 7, no. 4 (November 1989): 721–31. http://dx.doi.org/10.1017/s0263034600006194.

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The LIBRA light ion beam fusion commerical reactor study is a self-consistent conceptual design of a 330 MWe power plant with an accompanying economic analysis. Fusion targets are imploded by 4 MJ shaped pulses of 30 MeV Li ions at a rate of 3 Hz. The target gain is 80, leading to a yield of 320 MJ. The high intensity part of the ion pulse is delivered by 16 diodes through 16 separate z-pinch plasma channels formed in lOO torr of helium with trace amounts of lithium. The blanket is an array of porous flexible silicon carbide tubes with Li17Pb83 flowing downward through them. These tubes (INPORT units) shield the target chamber wall from both neutron damage and the shock overpressure of the target explosion. The target chamber is a right circular cylinder, 8·7 meters in diameter. The target chamber is ‘self-pumped’ by the target explosion generated overpressure into a surge tank partially filled with liquid that surrounds the target chamber. This scheme refreshes the chamber at the desired 3 Hz frequency without excessive pumping demands. The blanket multiplication is 1·2 and the tritium breeding ratio is 1·4. The direct capital cost of LIBRA is estimated to be $2200/kWe.

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25

Levina, Zh L., Yu P. Zheleznov, V. N. Molochnikova, A. I. Vinnikov, and V. V. Gorokhov. "Design and tests of cryogenic SKG-630 helium tanks." Chemical and Petroleum Engineering 26, no. 7 (July 1990): 357–59. http://dx.doi.org/10.1007/bf01147361.

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26

Bildsten, Lars. "Explosions on a Variety of Scales." Proceedings of the International Astronomical Union 7, S285 (September 2011): 71. http://dx.doi.org/10.1017/s1743921312000257.

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SummaryThe theoretical community is beginning to appreciate (and predict) the potential diversity of explosive outcomes from stellar evolution, while the supernovæ surveys are finding new kinds of supernovæ. This talk described two such new supernovæ. The first are ultraluminous core collapse supernovæ with radiated energies approaching 1051 ergs. The talk went on to present our recent work that explains these events with late-time energy deposition from rapidly rotating, highly magnetized neutron stars: magnetars. It concluded with our theoretical work on helium shell detonations on accreting white dwarfs that predict a new class of supernovæ called “.Ia's”. The first such candidate may well have been found by the Palomar Transient Factory.

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27

Conti, Peter S. "Parameters of Wolf-Rayet Stars." Symposium - International Astronomical Union 116 (1986): 199–214. http://dx.doi.org/10.1017/s0074180900148879.

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Wolf-Rayet (W-R) stars are objects with strong emission lines in the optical region due to a substantial stellar wind. They are found among the extreme Population I stars which are the topic of this Symposium and also this talk, and as central stars of planetary nebulae which I will not discuss here. The mass loss rates, Ṁ, are typically several 10−5 solar masses per year. W-R stars come in two major subtypes, the WN, in which strong lines of helium and nitrogen are seen, and the WC, in which strong lines of carbon and oxygen are found, along with the helium ions. In a few WN stars hydrogen appears to be present but the spectra of W-R stars are notable for the absence of this element. Absorption lines are generally not found in W-R stars, except in some instances due to a binary companion, or a more distant companion, or as a P-Cygni profile associated with certain emission features. An absorption spectrum appears to be an intrinsic feature in a very few WN stars.

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28

Kanne, W. R., D. A. Lohmeier, K. A. Dunn, and M. H. Tosten. "Metallographic analysis of helium-embrittlement cracking of repair welds in nuclear reactor tanks." Materials Characterization 30, no. 1 (January 1993): 23–34. http://dx.doi.org/10.1016/1044-5803(93)90005-g.

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29

Singh, Satish Kumar, Pravin Muneshwar, K. Naresh Kumar, Bhanu Pant, K. Sreekumar, and P. P. Sinha. "Development and Characterization of Ti5Al2.5Sn-ELI Alloy Hemispherical Domes for High-Pressure Cold Helium Tanks." Materials Science Forum 710 (January 2012): 113–18. http://dx.doi.org/10.4028/www.scientific.net/msf.710.113.

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Titanium alloys are used for high-pressure gas bottles / propellant tanks and structural applications owing to their high specific strength, good fabricability / weldability and compatibility with various working fluids. For these applications at ambient temperature, the workhorse Ti6Al4V alloy is extensively used. For the applications at low temperatures, two ELI grades of titanium alloys namely Ti6Al4V and Ti5Al2.5Sn are used as these retain toughness down to 77K and 4K respectively. Due to this inherent advantage, Ti5Al2.5Sn-ELI alloy has been selected as high pressure helium gas bottle submerged in liquid hydrogen (20K temperature). The gas bottle is spherical in shape and is made by electron beam welding of two machined hemispherical shells of 500 mm nominal diameter. The hemispherical shells for the difficult-to-forge Ti5Al2.5Sn-ELI alloy are developed through controlled closed-die forging operations. Shells are subsequently characterized for microstructures and mechanical properties at ambient temperature. Substantial increase in tensile strength with reasonably good ductility with respect to ambient temperature is achieved at 20K temperature. Multi point necking is observed at 20K. The present paper briefly outlines the process control devised for development of these domes and discusses the various characterization results obtained on forged hemispherical shells.

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30

Burbidge, G. "B2FH, the Cosmic Microwave Background and Cosmology." Publications of the Astronomical Society of Australia 25, no. 1 (2008): 30–35. http://dx.doi.org/10.1071/as07029.

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AbstractIn this talk I shall start by describing how we set about and carried out the work that led to the publication of Burbidge et al. (1957, hereafter B2FH). I then shall try and relate this work and the circumstances that surrounded it to the larger problem of the origin and formation of the universe. Here it is necessary to look back at the way that ideas developed and how, in many situations, astronomers went astray. Of course this is a personal view, though I very strongly believe that if he were still here, it is the approach that Fred Hoyle would take.I start by describing the problems originally encountered by Gamow and his associates in trying to decide where the helium was made. This leads me to a modern discussion of the origin of 2D, 3He, 4He and 7Li, originally described by B2FH as due to the x-process. While it is generally argued, following Gamow, Alpher, and Herman, that these isotopes were synthesised in a big bang I shall show that it is equally likely that these isotopes were made in active galactic nuclei, as was the cosmic microwave background (CMB), in a cyclic universe model. The key piece of observational evidence is that the amount of energy released in the conversion of hydrogen to helium in the universe is very close to the energy carried by the CMB, namely ∼4.5 × 10−13 erg cm−3.

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Birner, Benjamin, William Paplawsky, Jeffrey Severinghaus, and Ralph F. Keeling. "A method for resolving changes in atmospheric He ∕ N2 as an indicator of fossil fuel extraction and stratospheric circulation." Atmospheric Measurement Techniques 14, no. 3 (March 31, 2021): 2515–27. http://dx.doi.org/10.5194/amt-14-2515-2021.

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Abstract. The atmospheric He/N2 ratio is expected to increase due to the emission of He associated with fossil fuels and is expected to also vary in both space and time due to gravitational separation in the stratosphere. These signals may be useful indicators of fossil fuel exploitation and variability in stratospheric circulation, but direct measurements of He/N2 ratio are lacking on all timescales. Here we present a high-precision custom inlet system for mass spectrometers that continuously stabilizes the flow of gas during sample–standard comparison and removes all non-noble gases from the gas stream. This enables unprecedented accuracy in measurement of relative changes in the helium mole fraction, which can be directly related to the 4He/N2 ratio using supplementary measurements of O2/N2, Ar/N2 and CO2. Repeat measurements of the same combination of high-pressure tanks using our inlet system achieves a He/N2 reproducibility of ∼ 10 per meg (i.e., 0.001 %) in 6–8 h analyses. This compares to interannual changes of gravitational enrichment at ∼ 35 km in the midlatitude stratosphere of order 300–400 per meg and an annual tropospheric increase from human fossil fuel activity of less than ∼ 30 per meg yr−1 (bounded by previous work on helium isotopes). The gettering and flow-stabilizing inlet may also be used for the analysis of other noble-gas isotopes and could resolve previously unobserved seasonal cycles in Kr/N2 and Xe/N2.

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32

Richter, Svend. "Aldursgreiningar fylgdarlausra barna - hvers vegna og hvernig?" Tannlæknablaðið 38, no. 1 (2020): 22–34. http://dx.doi.org/10.33112/tann.38.1.3.

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UNICEF telur að fæðingar nærri þriðjungi (35%) barna undir fimm ára aldri hafa aldrei verið skráðar. Fæstar eru skráningarnar í Afríku sunnan Sahara (44%) og Suður Asíu (39%), þaðan sem flest fylgdarlaus börn koma og leita verndar í Evrópu. Mörg þeirra vita ekki um fæðingardag sinn og ferðast án viðeigandi persónuskilríkja. Vegna reglna um réttindi og skyldur einstaklinga sem sækja um alþjóðlega vernd, er lagalegur munur á hvort barn eða fullorðinn á í hlut. Því er yfirvöldum innflytjendamála mikilvægt að ganga úr skugga um hvort einstaklingur sé yngri eða eldri en 18 ára. Flest lönd Evrópu framkvæma réttarlæknisfræðilega aldursgreiningu ef ekki er hægt með hæfilegri vissu á grundvelli annarra tiltækra trúverðugra upplýsinga að meta aldur. Í aðeins tveimur löndum Evrópusambandsins, Bretlandi og Slóveníu, er aldursgreining byggð á viðtölum, án neinnar réttarlæknisfræðilegrar greiningar af neinu tagi. Langflest lönd Evrópu byggja aldursgreiningar á samþættingu tanna- og beinþroska. Öll Norðurlöndin nota þroska tanna til aldurgreininga og öll nota beinþroska. Þau lönd sem nota þroska beina til aldursgreininga nota öll hönd og úlnlið, nema Svíþjóð sem notar hné. Í Danmörku, eitt Norðurlanda, er notað mat á kynþroska við aldursákvörðun. Nokkur ágreiningur hefur verið um aldursgreiningar í Noregi, Svíþjóð og Íslandi. Nokkrar sérfræðigreinar hafa verið kallaðar til að sjá um breytingar til bóta í Noregi og Svíþjóð: tannlækningar, barnalækningar, röntgenfræði, en einnig hefur verið gerð tölfræðilíkön og myndgreining. Þeir sem helst hafa haft sig frammi um hvernig best sé staðið að aldursgreiningu hér á landi hafa ekki komið frá þessum sérfræðigreinum heldur alls óskyldum. Gerður var samningur milli Útlendingastofnunar og Háskóla Íslands sem ekki var endurnýjaður eftir eitt ár þar sem HÍ taldi að ÚTL hefði ekki uppfyllt samninginn.

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Karim, G. A., and V. Panlilio. "Flame Propagation and Lean-Limit Extinction Within Stratified Mixtures Involving a Diluent Gas." Journal of Energy Resources Technology 114, no. 3 (September 1, 1992): 216–20. http://dx.doi.org/10.1115/1.2905944.

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Flame propagation within confined, stratified gaseous environments were investigated experimentally. The diluents nitrogen and helium were used in turn to overlay initially combustible methane-air or hydrogen-air mixtures. Gas stratification was achieved by allowing the two initially homogeneous gases to interdiffuse for a certain period of time at constant temperature and pressure within a long, vertical, smooth, closed, circular tube. Upward flame propagation was examined following spark ignition while the tube was closed at the top but open at the bottom. Near-extinction flame speeds, lower than those predicted according to Davies and Taylor (1950), were obtained with helium dilution. Moreover, estimated reactant concentrations at the observed location of flame extinction indicated, in specific instances, that mixture stratification appears to slightly enhance locally the lean flammability limit. Nonuniform, stratified combustible gaseous mixtures and flame propagation within such mixtures are found in many situations, including in numerous technical applications, as well as in various potentially hazardous circumstances. The leakage of a fuel from storage tanks or pipelines, the formation of layered combustible mixtures within rooms, corridors, or elevator shafts of buildings, the formation of gas pockets in coal mine galleries, and the inerting of flammable mixtures through diluent gas addition are some examples. Some relevant information about the stratification process and the flame propagation characteristics in these specific circumstances has already been reported in the literature by Bakke and Leach (1962), James and Purdy (1962), Girard et al. (1979), Karim and Lam (1986) and Karim et al. (1987). This investigation considers some aspects of flame propagation and mass transfer within confined, stratified gaseous environment. The diluents nitrogen and helium were used in turn to overlay initially combustible methane-air or hydrogen-air mixtures. Mixture stratification was produced by permitting the two initially homogeneous gaseous systems to interdiffuse at constant temperature within a long, vertical, smooth, closed, circular tube. Only upward flame propagation was examined, as this mode is expected to involve the widest flammability limits and the fastest propagation for both homogeneous and stratified methane-air mixtures when confined in tubes (Liebman et al., 1971).

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Li, Ze, and Tao Song. "Study on Mixture Ratio Control of Bipropellant Propulsion System on Satellite Based on Bypass Control System." Applied Mechanics and Materials 390 (August 2013): 338–42. http://dx.doi.org/10.4028/www.scientific.net/amm.390.338.

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Bipropellant propulsion system (MON-1MMH) provides motivation for orbit transfer, attitude control and station keeping, is mainly applied for GEO satellite. Most bipropellant propulsion systems of satellite do not have the ability to control mixture ratio of oxidizer and fuel. The primary function of bypass control system, as an important part of bipropellant propulsion system, is to control helium pressure in the propellant tanks in order to control mixture ratio. This paper researches adjustment of mixture ratio for bipropellant propulsion system. Mathematical model for key components in bypass control system of bipropellant propulsion system and a reasonable model for system simulation combining the practical work of system is established. Through the dynamic simulation of Bang-Bang control with on-off solenoid valve for the adjustment of mixture ratio, structure parameters, working parameters and precision of feedback are all be considered for influence of system performance. The main factors affecting system performance are found out. The researches provide theoretical foundation for engineering implementation.

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Rangasamy, R. G., and Prabhat Kumar. "Quality Management during Manufacturing of High Tempertaure Thin Walled Austenitic Stainless Steel Sodium Tanks of Prototype Fast Breeder Reactor." Advanced Materials Research 794 (September 2013): 507–13. http://dx.doi.org/10.4028/www.scientific.net/amr.794.507.

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Austenitic stainless steels are the major material of construction for the fast breeder reactors in view of their adequate high temperature mechanical properties, compatibility with liquid sodium coolant, good weldability, availability of design data and above all the fairly vast and satisfactory experience in the use of these steels for high temperature service. All the Nuclear Steam Supply System (NSSS) components of FBR are thin walled structure and require manufacture to very close tolerances under nuclear clean conditions. As a result of high temperature operation and thin wall construction, the acceptance criteria are stringent as compared to ASME Section III. The material of construction is Austenitic stainless steel 316 LN and 304 LN with controlled Chemistry and calls for additional tests and requirements as compared to ASTM standards. Prototype Fast Breeder Reactor (PFBR) is sodium cooled, pool type, 500 MWe reactor which is at advanced stage of construction at Kalpakkam, Tamilnadu, India. In PFBR, the normal heat transport is mainly through two secondary loops and in their absence; the decay heat removal is through four passive and independent safety grade decay heat removal loops (SGDHR). The secondary sodium circuit and the SGHDR circuit consist of sodium tanks for various applications such as storage, transfer, pressure mitigation and to take care of volumetric expansion. The sodium tanks are thin walled cylindrical vertical vessels with predominantly torispherical dished heads at the top and bottom. These tanks are provided with pull-out nozzles which were successfully made by cold forming. Surface thermocouples and heaters, wire type leak detectors are provided on these tanks. These tanks are insulated with bonded mineral wool and with aluminum cladding. All the butt welds in pressure parts were subjected to 100% Radiographic examination. These tanks were subjected to hydrotest, pneumatic test and helium leak test under vacuum. The principal material of construction being stainless steel for the sodium tanks shall be handled with care following best engineering practices coupled with stringent QA requirements to avoid stress corrosion cracking in the highly brackish environment. Intergranular stress corrosion cracking and hot cracking are additional factors to be addressed for the welding of stainless steel components. Pickling and passivation, Testing with chemistry controlled demineralised water are salient steps in manufacturing. Corrosion protection and preservation during fabrication, erection and post erection is a mandatory stipulation in the QA programme. Enhanced reliability of welded components can be achieved mainly through quality control and quality assurance procedures in addition to design and metallurgy. The diverse and redundant inspections in terms of both operator and technique are required for components where zero failure is desired & claimed. This paper highlights the step by step quality management methodologies adopted during the manufacturing of high temperature thin walled austenitic stainless steel sodium tanks of PFBR.

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Soroka, A. I., and V. A. Lyakh. "Polygenic Inheritance of Bracts Number in Sunflower." Helia 42, no. 71 (November 18, 2019): 221–28. http://dx.doi.org/10.1515/helia-2019-0004.

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Abstract Two inbreds of mutant origin, differing in the number of bracts, were crossed to obtain the F1 hybrid. One mutant line had 24.5 ± 1.01 bracts, while the other, 78.6 ± 1.69 bracts. The F1 hybrid had an average value between parents, which practically did not differ from the mean value in the F2 population. The variability of the trait under study in the F2 population was continuous, varying from 20 to 84 bracts. This indicated the probable participation of several genes with an additive effect in the control of the number of bracts. Assuming that the differences between the parental lines are due to two pairs of genes, the F2 plant population, grown in 2016, was divided into 5 classes. In that population the observed classes ratio turned out to be close to the theoretically expected ratio of 1 : 4 : 6 : 4 : 1. Over the next two years F2 populations were tested in a similar way. In all the cases, the calculated chi-square value did not exceed the critical value for 4 degrees of freedom and 5 % significance level. This gave reason to talk about the two-loci control of a such quantitative trait as the number of bracts. The participation of two non-allelic genes in the control of this trait is also proved by matching the actual number of plants in the parental classes to the theoretically expected number of plants. Thus, the number of bracts depends on the number of dominant alleles of two different genes in the genotype.

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García-Lario, Pedro. "Early Herschel results on evolved stars and planetary nebulae." Proceedings of the International Astronomical Union 7, S283 (July 2011): 33–40. http://dx.doi.org/10.1017/s1743921312010654.

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AbstractHerschel, an ESA space observatory equipped with science instruments provided by European-led Principal Investigator consortia with important participation from NASA, was launched on 14 May 2009. With its 3.5m diameter primary mirror, Herschel is the largest space telescope ever launched into space, and carries onboard three science instruments, whose focal plane units are cryogenically cooled inside a superfluid helium cryostat. The PACS and SPIRE instruments provide broadband imaging photometry in six bands centred at 75, 100, 160, 250, 350, and 500 microns and imaging spectroscopy over the range 55–672 microns. The HIFI instrument provides very high-resolution heterodyne spectroscopy over the ranges 157–212 and 240–625 microns. The results obtained already in the first year and a half of routine science operations demonstrate that Herschel will have strong impact on all research fields, from Solar System studies to the area of Cosmology, from the analysis of star formation to the mysteries of galaxy formation. In this talk I will review the Herschel highlights in the area of evolved stars in general and of planetary nebulae more in particular, resulting from observations performed with the three instruments onboard Herschel since launch. This will be exemplified by a few observational results, just the tip of the iceberg of what is yet to come in the remaining year and a half of science operations.

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Hensel, Friedrich, Daniel R. Slocombe, and Peter P. Edwards. "On the occurrence of metallic character in the periodic table of the chemical elements." Philosophical Transactions of the Royal Society A: Mathematical, Physical and Engineering Sciences 373, no. 2037 (March 13, 2015): 20140477. http://dx.doi.org/10.1098/rsta.2014.0477.

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The classification of a chemical element as either ‘metal’ or ‘non-metal’ continues to form the basis of an instantly recognizable, universal representation of the periodic table (Mendeleeff D. 1905 The principles of chemistry , vol. II, p. 23; Poliakoff M. & Tang S. 2015 Phil. Trans. R. Soc. A 373 , 20140211). Here, we review major, pre-quantum-mechanical innovations (Goldhammer DA. 1913 Dispersion und Absorption des Lichtes ; Herzfeld KF. 1927 Phys. Rev. 29 , 701–705) that allow an understanding of the metallic or non-metallic status of the chemical elements under both ambient and extreme conditions. A special emphasis will be placed on recent experimental advances that investigate how the electronic properties of chemical elements vary with temperature and density, and how this invariably relates to a changing status of the chemical elements. Thus, the prototypical non-metals, hydrogen and helium, becomes metallic at high densities; and the acknowledged metals, mercury, rubidium and caesium, transform into their non-metallic forms at low elemental densities. This reflects the fundamental fact that, at temperatures above the absolute zero of temperature, there is therefore no clear dividing line between metals and non-metals. Our conventional demarcation of chemical elements as metals or non-metals within the periodic table is of course governed by our experience of the nature of the elements under ambient conditions. Examination of these other situations helps us to examine the exact divisions of the chemical elements into metals and non-metals (Mendeleeff D. 1905 The principles of chemistry , vol. II, p. 23).

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Skårup, Povl. "Dicuil um Føroyar / Dicuil about the Faroe Islands." Fróðskaparrit - Faroese Scientific Journal 57 (February 26, 2017): 5. http://dx.doi.org/10.18602/fsj.v57i0.68.

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Úrtak: Liber de Mensura Orbis Terrae (825 e. Kr.) eftir Dicuil er tann elsti kendi teksturin, har ið Føroyar helst verða umrøddar. Niðanfyri verður henda umrøða endurgivin í tí latínska upprunatekstinum saman við einari enskari týðing, bæði eftir útgávuni frá 1967 og við mínum viðmerkingum. Dentur verður serliga lagdur á at granska ein ávísan setning í tekstinum. Hesin setningur hevur verið støðið undir tí tilgiting, at ein partur av tí, sum hevur verið hildið at snúgva seg um Føroyar, heldur er um Hetland. At enda verður ein onnur tilgiting umrødd. Henda tilgiting setur fram, at einki í umrødda tekstinum snýr seg um Føroyar. Tilgitingarnar verða báðar frávístar. Summary: Dicuil’s Liber de Mensura Orbis Terrae (A.D. 825) is the oldest known text to contain a probable reference to the Faroe Islands. The excerpt in question is provided below in the Latin original and in English translation, both from the 1967 edition, followed by my com- ments. One sentence in the excerpt in particular is discussed. The sentence has been used to support a hypothesis that a part of what is traditionally thought to refer to the Faroe Islands, may instead refer to the Shetlands. Finally a second hypothesis is discussed. This hypothesis proposes that nothing in the text in question refers to the Faroe Islands. Both hypotheses are rejected.

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Brix, Kirsten. "Menningarástøði og hugmyndafrøði - Brotmynd í 4 pørtum um vald og kyn við støði í bókmentaligari viðgerð / The Theory of Evolution and Ideology - A Mosaic in Four Parts on Power and Gender Based on a Reading of Three Literary Texts." Fróðskaparrit - Faroese Scientific Journal 57 (February 26, 2017): 77. http://dx.doi.org/10.18602/fsj.v57i0.73.

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Úrtak: Menningarástøðið eftir Charles Darwin elvdi frá fyrsta degi til mótstøðu bæði frá vísindaligari og átrúnaðarligari síðu. Seinni hava rannsóknir innan fyri ymiskar vísindagreinir við nýggjari tøkni prógvað hansara niðurstøður, og menningarástøðið er viðurkent sum vísindaligt ástøði. Men hugmyndafrøðiliga heldur stríðið fram. Tann nýggjasta royndin at útihýsa menningarástøðinum frá undirvísingini í skúlum og øðrum lærustovnum er at fáa tað, sum verður nevnt intelligent design, viðurkent sum vísindaligt ástøði. Greinin viðger við støði í trimum bókmentaligum tekstum ymisk brigdi í tí hugmyndafrøðiliga stríðnum og vísir á, at stríðið ikki snýr seg um vitan og sannleikar, men um tamarhald og vald.Abstract: From the beginning, Darwin´s theory of evolution led to opposition from science and religion alike. Later, research carried out within diﬀerent branches of science and using the most advanced technology has proved the validity of his conclusions and the theory of evolution has been established as a scientiﬁc theory. However, the ideological battle has far from ended. The most recent attempt to have the theory of evolution excluded from schools and other institutions of learning is having what is called intelligent design established as a scientiﬁc theory. Using three literary texts as points of departure, the writer deals with diﬀerent aspects of this ideological battle and concludes that this is not, indeed, a controversy about knowledge and truth, but about control and power.

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Weyhe, Eivind. "Ein táttur eftir Sjóvarbóndan – ella tveir? / A Faroese jocular ballad by Sjóvarbóndin – or two?" Fróðskaparrit - Faroese Scientific Journal 58 (February 26, 2017): 41. http://dx.doi.org/10.18602/fsj.v58i0.60.

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Úrtak: Í greinini vísir høvundurin á at tann tátturin sum í Føroya kvæðum ber heitið „Mikkjals táttur“ (CCF 201), í roynd og veru er yrktur av Jens Chr. Djurhuus, Sjóvarbóndanum eldra (1773-1853). Víst verður eisini á at samband má vera millum henda táttin og ein annan tátt, „Abba Nouva“, sum í illa bronglaðum líki stendur í kvæðahandritinum Fugloyarbók (frá fyri 1854). Høvundurin heldur góð sannlíkindir vera til at báðir tættirnir hava sama høvuðspersón, og hann gevur eitt boð upp á hvør hesin hevur verið. Eisini setur høvundurin fram ta tilgiting at Sjóvarbóndin kann hava yrkt báðar tættirnar. Abstract: The article shows that the jocular ballad entitled Mikkjals táttur in Føroya kvæði (CCF 201), was in fact composed by Jens Chr. Djurhuus, popularly known as Sjóvarbóndin eldri (‘Sjóvarbóndin the older’, 1773-1853) after his farm, Sjógv, in Kollafjørður. A case is also made for there being a connection between Mikkjals táttur and another ballad, Abba Nouva, which appears in extremely garbled form in the ballad manuscript Fugloyarbók (from before 1854). The author considers there is a strong likelihood both ballads portray one and the same person, and he hazards a guess about who this person might have been. It is also suggested that Djurhuus may be behind both ballads.

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Skuhravá, Marcela, and Václav Skuhravý. "Plant galls and gall midges (Diptera: Cecidomyiidae) of the Faroe Islands in the Atlantic Ocean / Plantuvølir og vølamíggj (Diptera: Cecidomyiidae) í Føroyum." Fróðskaparrit - Faroese Scientific Journal 57 (February 26, 2017): 115. http://dx.doi.org/10.18602/fsj.v57i0.77.

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Úrtak: Tíggju vølelvandi og vølatknýttar lívverur, ið komu fyri á sjey vertsplantusløgum, ið hoyrdu til sjey plantuættir, vórðu funnar nærindis Tórshavn í august 2005. Av teimum eru fimm sløg vølamíggj (Cecidomyiidae, Diptera), tvey eru eriophyid-mottur (Eriophyioidea, Acarina) og trý hoyra til ymsar soppaættir. Allir finningar eru nýggjar skrásetingar í Føroyum. Sjey sløg elva til vølir á ymsum vertsplantum, nevniliga Cecidomyiidae, Oligotrophus juniperinus, ið elvir til knubbavølir á vanligum baraldi, Juniperus communis, og Contarinia floriperda, ið elvir til blómuknubbavølir á einum slag av royniviði, Sorbus aria; Eriophyoidea, Aceria pseudoplatani, á bløð á einum slag av ahorn, Acer pseudoplatanus, og Aculus anthobius á stelk og blómur á einum slag av steinbrá, Galium anisophyllum; og soppurin Cronartium ribicola, ið elvir til vølir á bløð á sólberjarunni, Ribes nigrum, og Melampsora caprearum á bløð á pálmapíli, Salix phylicifolia, og Puccinia violae á bløð á dimmari blákollu, Viola riviniana. Trý vølamíggj, ið ikki elva til vølir, eru knýtt at vølelvandi lívverum, nevniliga Mycodiplosis melampsorae og Clinodiplosis cilicrus, bæði planturotátin (phytosaprophagous) sløg, ið eru knýtt at rotnum plantutilfari, og Feltiella acarisuga, eitt djóraátið (zoophagous) slag, ið gagnnýtir tetranychid-mottur. Oligotrophus juniperinus, Contarinia floriperda og Puccinia violae eru upprunalig í Føroyum í sambandi við upprunan at vertsplantuni; og tey sløg, ið eru eftir, eru fremmand og eru vorðin innslødd til Føroya við fólki. Frá einum lívfrøði- landafrøðiligum sjónarmiði eru Oligotrophus juniperinus, Contarinia floriperda, Aceria pseudoplatani og Aculus anthobius evropisk sløg, Mycodiplosis melampsorae og Clinodiplosis cilicrus eru evro-sibirisk sløg og Feltiella acarisuga er eitt alheimsslag. Finningurin av C. floriperda í Føroyum er tann norðasta fyrikomingin í Evropa. Tað lága talið á sløgum av vølelvandi lívverum í Føroyum kemst av landafrøðiligari avbyrging og natúrligum umstøðum í landinum, t.e. heldur lítil gróður og trot á trøum og runnum, sum kundu verið møguligar vertsplantur hjá vølelvandi lívverum.Abstract :Ten gall-causing and gall-associated organisms occurring on seven host plant species belonging to seven plant families were found near Tórshavn on the island of Streymoy, one of the Faroe Islands, in August 2005. Of these, ﬁve species are gall midges (Cecidomyiidae, Diptera), two are eriophyid mites (Eriophyioidea, Acarina) and three belong to various families of fungi. All ﬁndings are new records for the Faroe Islands. Seven species cause galls on various host plants, namely the Cecidomyiidae, Oligotrophus juniperinus causing bud galls on Juniperus communis and Contarinia ﬂoriperda inducing ﬂower bud galls on Sorbus aria; the Eriophyoidea, Aceria pseudoplatani on leaves of Acer pseudoplatanus and Aculus anthobius on stems and ﬂowers of Galium anisophyllum; and the fungi Cronartium ribicola galling leaves of Ribes nigrum, Melampsora caprearum on leaves of Salix phylicifolia and Puccinia violae on leaves of Viola riviniana. Three non-galling gall midges were associated with gall-causing organisms, viz. Mycodiplosis melampsorae and Clinodiplosis cilicrus, both phytosaprophagous species associated with decaying plant matter, and Feltiella acarisuga, a zoophagous species preying on tetranychid mites. Oligotrophus juniperinus, Contarinia ﬂoriperda and Puccinia violae are native to the Faroe Islands with regard to the origin of their host plants; and the remaining species are alien and were introduced to the Faroe Islands by man. From the biogeographical point of view Oligotrophus juniperinus, Contarinia ﬂoriperda, Aceria pseudoplatani and Aculus anthobius are European species, Mycodiplosis melampsorae and Clinodiplosis cilicrus are Euro-Siberian species and Feltiella acarisuga is a cosmopolitan species. The ﬁnding of C. ﬂoriperda in the Faroe Islands is the most northern occurrence in Europe. The low species number of gall-causing organisms in the Faroe Islands is the result of geographical isolation and natural conditions of these islands with relatively poor vegetation and lack of trees and shrubs, which may be potential host plants of gall-causing organisms.

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43

"Helium Beer, From Prank To Tank." Chemical & Engineering News Archive 93, no. 43 (November 2, 2015): 56. http://dx.doi.org/10.1021/cen-09343-newscripts.

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"SpaceX traces Falcon 9 explosion to helium tank breach." Physics Today, 2016. http://dx.doi.org/10.1063/pt.5.0210126.

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Mitikov, Yurii A., and Serhii A. Kuda. "Influence of hot helium input speed on parameters of pressurization system of prolongated fuel tank." Collection of Scientific Publications NUS, no. 3 (November 8, 2016). http://dx.doi.org/10.15589/jnn20150310.

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46

Nayebzadeh, Arash, Hanieh Tabkhi, and Yoav Peles. "Hydrodynamic Cavitation Downstream a Micropillar Entrained Inside a Microchannel—A Parametric Study." Journal of Fluids Engineering 141, no. 1 (June 27, 2018). http://dx.doi.org/10.1115/1.4040374.

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Hydrodynamic cavitation downstream a range of micropillar geometries entrenched in a microchannel were studied experimentally. Pressurized helium gas at the inlet tank and vacuum pressure at the outlet propelled distilled water through the device and trigger cavitation. The entire process from cavitation inception to the development of elongated attached cavity was recorded. Three modes of cavitation inception were observed and key parameters of cavitation processes, such as cavity length and angle of attachment, were compared among various micropillar geometries. Cavitation downstream of a triangular micropillar was found to have a distinct inception mode with relatively high cavitation inception numbers. After reaching its full elongated form, it prevailed through a larger system pressures and possessed the longest attached cavity. Cavity angle of attachments was predominantly related to the shape of the micropillar. Micropillars with sharp vertex led to lower cavity attachment angles close to the flow separation point, while circular micropillars resulted in higher angles. Twin circular micropillars have a unique cavitation pattern that was affected by vortex shedding. Fast Fourier transformation (FFT) analysis of the cavity image intensity revealed transverse cavity shedding frequencies in various geometries and provided an estimation for vortex shedding frequencies.

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47

Gad-Briggs, A., P. Pilidis, and T. Nikolaidis. "Analyses of the Load Following Capabilities of Brayton Helium Gas Turbine Cycles for Generation IV Nuclear Power Plants." Journal of Nuclear Engineering and Radiation Science 3, no. 4 (July 31, 2017). http://dx.doi.org/10.1115/1.4036983.

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The control system for generation IV nuclear power plant (NPP) design must ensure load variation when changes to critical parameters affect grid demand, plant efficiency, and component integrity. The objective of this study is to assess the load following capabilities of cycles when inventory pressure control is utilized. Cycles of interest are simple cycle recuperated (SCR), intercooled cycle recuperated (ICR), and intercooled cycle without recuperation (IC). First, part power performance of the IC is compared to results of the SCR and ICR. Subsequently, the load following capabilities are assessed when the cycle inlet temperatures are varied. This was carried out using a tool designed for this study. Results show that the IC takes ∼2.7% longer than the ICR to reduce the power output to 50% when operating in design point (DP) for similar valve flows, which correlates to the volumetric increase for the IC inventory storage tank. However, the ability of the IC to match the ICR's load following capabilities is severely hindered because the IC is most susceptible to temperature variation. Furthermore, the IC takes longer than the SCR and ICR to regulate the reactor power by a factor of 51 but this is severely reduced, when regulating NPP power output. However, the IC is the only cycle that does not compromise reactor integrity and cycle efficiency when regulating the power. The analyses intend to aid the development of cycles specifically gas-cooled fast reactors (GFRs) and very high temperature reactors (VHTRs), where helium is the coolant.

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Gad-Briggs, A., P. Pilidis, and T. Nikolaidis. "Analyses of the Control System Strategies and Methodology for Part Power Control of the Simple and Intercooled Recuperated Brayton Helium Gas Turbine Cycles for Generation IV Nuclear Power Plants." Journal of Nuclear Engineering and Radiation Science 3, no. 4 (July 31, 2017). http://dx.doi.org/10.1115/1.4036737.

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An important requirement for Generation IV Nuclear Power Plant (NPP) design is the control system, which enables part power operability. The choices of control system methods must ensure variation of load without severe drawbacks on cycle performance. The objective of this study is to assess the control of the NPP under part power operations. The cycles of interest are the simple cycle recuperated (SCR) and the intercooled cycle recuperated (ICR). Control strategies are proposed for NPPs but the focus is on the strategies that result in part power operation using the inventory control method. First, results explaining the performance and load limiting factors of the inventory control method are documented; subsequently, the transient part power performances are also documented. The load versus efficiency curves were also derived from varying the load to understand the efficiency penalties. This is carried out using a modeling and performance simulation tool designed for this study. Results show that the ICR takes ∼102% longer than the SCR to reduce the load to 50% in design point (DP) performance conditions for similar valve flows, which correlates with the volumetric increase for the ICR inventory tank. The efficiency penalties are comparable for both cycles at 50% part power, whereby a 22% drop in cycle efficiency was observed and indicates limiting time at very low part power. The analyses intend to aid the development of cycles for Generation IV NPPs specifically gas cooled fast reactors (GFRs) and very high-temperature reactors (VHTRs), where helium is the coolant.

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49

"Helium Porosity Development During Annealing of Helium-Implanted 18Cr10NiTi Steel." East European Journal of Physics, no. 4 (2018). http://dx.doi.org/10.26565/2312-4334-2018-4-08.

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The kinetics of helium porosity development during annealing of 18Cr10NiTi stainless steel irradiated with 20 keV helium ions at room temperature for simultaneous creation of displacement damage at a level of 0.5–5 dpa and a helium concentration of 1–12 at.%, have been investigated by electron microscopy and thermal desorption spectrometry. The temperature ranges of helium release from steel and their dependence on the irradiation dose are determined. The evolution of 18Cr10NiTi steel microstructure was investigated during post-implantation annealing in the temperature range from Troom to 1420 K. At a dose of 1·1020 m-2, helium bubbles were detected only after annealing to a temperature of 890 K, while at a dose of 1·1021 m-2, bubbles were observed immediately after radiation at Troom. During annealing, the average diameters of the bubbles vary from ~1 nm at Troom to 10–20 nm at Tann 1420 K. The mechanisms of bubbles growth either by migration and coalescence, or by Ostwald ripening – dissolution and re-trapping are considered. Since each of these mechanisms corresponds to a certain trend of bubbles size and density dependence on the annealing temperature, the temperature dependences of average diameters and densities of helium bubbles for a dose of 1·1021 m-2 have been constructed and analyzed. Experimental data are characterized by three temperature ranges: 1 – from 300 to 760 K, 2 – from 760 to 1030 K, and 3 – from 1030 to 1350 K with clearly differing trends. In the low-temperature region the diameter and density of the bubbles virtually does not change. Their size increases and the density decreases at annealing in the temperature range 760-1030 K. This tendency intensifies in the temperature range of 1030-1420 K. An estimation of activation energy of the processes controlling the mechanism of bubble growth in the temperature range of 1000-1420 K has been done. An obtained value of ~3.7 eV correlates well with the theoretically calculated value of the activation energy of the dissociation process (EHediss) of the Ostwald ripening mechanism.

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Ghazaryan, S., G. Alecian, and A. A. Hakobyan. "Statistical analysis of the new catalogue of CP stars." Communications of the Byurakan Astrophysical Observatory, 2018, 223–27. http://dx.doi.org/10.52526/25792776-2018.2.2-223.

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This talk is devoted to the statistical analysis of the new catalogue of Chemically Peculiar stars compiled from papers, where chemical abundances of those stars were given. The catalogue contains chemical abundances and physical parameters of 428 stars based on high-resolution spectroscopy data. Spearman's rank correlation test was applied for 416 CP (108 HgMn, 188 ApBp and 120 AmFm) stars and the correlation between chemical abundances and different physical parameters (effective temperature, surface gravity and rotational velocity) was checked. From dozens interesting cases we secluded four cases: the Mn peculiarities in HgMn stars, the Ca correlation with respect to effective temperature in AmFm stars, the case of helium and iron in ApBp stars. We applied also Anderson-Darling (AD) test on ApBp stars to check if multiplicity is a determinant parameter for abundance peculiarities.

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Journal articles on the topic 'Helium tank'

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