scholarly journals Coupling thermal evolution of planets and hydrodynamic atmospheric escape in mesa

2020 ◽  
Vol 499 (1) ◽  
pp. 77-88 ◽  
Author(s):  
Daria Kubyshkina ◽  
Aline A Vidotto ◽  
Luca Fossati ◽  
Eoin Farrell
Keyword(s):  
Mass Fraction ◽  
Thermal State ◽  
Thermal Evolution ◽  
Detailed Comparison ◽  
Planetary Atmospheres ◽  
Gravitational Energy ◽  
Atmospheric Escape ◽  
Mass Fractions ◽  
The Stability ◽  
Atmospheric Mass

ABSTRACT The long-term evolution of hydrogen-dominated atmospheres of sub-Neptune-like planets is mostly controlled to by two factors: a slow dissipation of the gravitational energy acquired at the formation (known as thermal evolution) and atmospheric mass-loss. Here, we use mesa to self-consistently couple the thermal evolution model of lower atmospheres with a realistic hydrodynamical atmospheric evaporation prescription. To outline the main features of such coupling, we simulate planets with a range of core masses (5–20 M⊕) and initial atmospheric mass fractions (0.5–30 per cent), orbiting a solar-like star at 0.1 au. In addition to our computed evolutionary tracks, we also study the stability of planetary atmospheres, showing that the atmospheres of light planets can be completely removed within 1 Gyr and that compact atmospheres have a better survival rate. From a detailed comparison between our results and the output of the previous-generation models, we show that coupling between thermal evolution and atmospheric evaporation considerably affects the thermal state of atmospheres for low-mass planets and, consequently, changes the relationship between atmospheric mass fraction and planetary parameters. We, therefore, conclude that self-consistent consideration of the thermal evolution and atmospheric evaporation is of crucial importance for evolutionary modelling and a better characterization of planetary atmospheres. From our simulations, we derive an analytical expression between planetary radius and atmospheric mass fraction at different ages. In particular, we find that, for a given observed planetary radius, the predicted atmospheric mass fraction changes as age0.11.

scholarly journals Effect of MF-Coated Epoxy Resin Microcapsules on Properties of Waterborne Wood Coating on Basswood

Coatings ◽  
2020 ◽  
Vol 10 (8) ◽  
pp. 785 ◽  
Author(s):  
Xiaoxing Yan ◽  
Yijuan Chang
Keyword(s):  
Epoxy Resin ◽  
Mass Fraction ◽  
High Performance ◽  
Impact Resistance ◽  
Color Difference ◽  
Core Material ◽  
Wall Material ◽  
The Core ◽  
Mass Fractions ◽  
The Stability

In this paper, melamine–formaldehyde (MF) was used as the wall material, and epoxy resin was used as the core material to prepare microcapsules. The optical properties, mechanical properties and ageing resistance of waterborne topcoat were investigated by adding different mass fractions of microcapsules into the waterborne topcoat. Through scanning electron microscopy and infrared spectroscopy analysis, the prepared microcapsules of core-wall ratio of 0.50 were more uniform. It was found that when the mass fraction of microcapsules is less than 10.0% and the core–wall ratio is 0.50, the original color difference of the coating can be maintained. With the increase in microcapsule mass fraction, the gloss of the topcoat film gradually decreases. The mass fraction of the microcapsule of 4.0% with the core–wall ratio of 0.50 can maintain the original gloss of 30.0 GU. The topcoat film with the MF-coated epoxy resin microcapsules of the core–wall ratio of 0.50 has high impact resistance, adhesion and hardness. The results showed that the gloss loss and color difference of the coating with the MF-coated epoxy microcapsules were the lowest when the mass fraction of microcapsules was 4.0%, indicating that microcapsules can improve the stability of coating. These results lay a technical foundation for the development and application of high-performance wood coatings.

A technique for uranium and plutonium determination using coulometric potentiostatic facility UPK-19 for analysis of mixed-oxide fuel

2020 ◽  
Vol 86 (12) ◽  
pp. 15-22
Author(s):  
N. A. Bulayev ◽  
E. V. Chukhlantseva ◽  
O. V. Starovoytova ◽  
A. A. Tarasenko
Keyword(s):  
Acid Solution ◽  
Mass Fraction ◽  
Background Electrolyte ◽  
Stable State ◽  
Sulfamic Acid ◽  
Oxide Fuel ◽  
Oxidation Current ◽  
Mox Fuel ◽  
Mass Fractions ◽  
Uranium Plutonium

The content of uranium and plutonium is the main characteristic of mixed uranium-plutonium oxide fuel, which is strictly controlled and has a very narrow range of the permissible values. We focused on developing a technique for measuring mass fractions of uranium and plutonium by controlled potential coulometry using a coulometric unit UPK-19 in set with a R-40Kh potentiostat-galvanostat. Under conditions of sealed enclosures, a special design of the support stand which minimized the effect of fluctuations in ambient conditions on the signal stability was developed. Optimal conditions for coulometric determination of plutonium and uranium mass fractions were specified. The sulfuric acid solution with a molar concentration of 0.5 mol/dm3 was used as a medium. Lead ions were introduced into the background electrolyte to decrease the minimum voltage of hydrogen reduction to –190 mV. The addition of aluminum nitride reduced the effect of fluoride ions participating as a catalyst in dissolving MOX fuel samples, and the interfering effect of nitrite ions was eliminated by introducing a sulfamic acid solution into the cell. The total content of uranium and plutonium was determined by evaluation of the amount of electricity consumed at the stage of uranium and plutonium co-oxidation. Plutonium content was measured at the potentials, at which uranium remains in the stable state, which makes it possible to subtract the contribution of plutonium oxidation current from the total oxidation current. The error characteristics of the developed measurement technique were evaluated using the standard sample method and the real MOX fuel pellets. The error limits match the requirements set out in the specifications for MOX fuel. The technique for measuring mass fractions of uranium and plutonium in uranium-plutonium oxide nuclear fuel was certified. The relative measurement error of the mass fraction of plutonium and uranium was ±0.0070 and ±0.0095, respectively. The relative error of the ratio of the plutonium mass fraction to the sum of mass fractions of uranium and plutonium was ±0.0085.

scholarly journals Numerical Investigation of the Effect of Air Leaking into the Working Fluid on the Performance of a Steam Ejector

2021 ◽  
Vol 11 (13) ◽  
pp. 6111
Author(s):  
He Li ◽  
Xiaodong Wang ◽  
Jiuxin Ning ◽  
Pengfei Zhang ◽  
Hailong Huang
Keyword(s):  
Flow Structure ◽  
Mass Fraction ◽  
Internal Flow ◽  
Working Fluid ◽  
Physical Parameters ◽  
Entrainment Ratio ◽  
Air Mass ◽  
Steam Ejector ◽  
Primary Fluid ◽  
Mass Fractions

This paper investigated the effect of air leaking into the working fluid on the performance of a steam ejector. A simulation of the mixing of air into the primary and secondary fluids was performed using CFD. The effects of air with a 0, 0.1, 0.3 and 0.5 mass fraction on the entrainment ratio and internal flow structure of the steam ejector were studied, and the coefficient distortion rates for the entrainment ratios under these air mass fractions were calculated. The results demonstrated that the air modified the physical parameters of the working fluid, which is the main reason for changes in the entrainment ratio and internal flow structure. The calculation of the coefficient distortion rate of the entrainment ratio illustrated that the air in the primary fluid has a more significant impact on the change in the entrainment ratio than that in the secondary fluid under the same air mass fraction. Therefore, the air mass fraction in the working fluid must be minimized to acquire a precise entrainment ratio. Furthermore, this paper provided a method of inspecting air leakage in the experimental steam ejector refrigeration system.

Numerical and Experimental Investigation Into the Effects of Nanoparticle Mass Fraction and Bubble Size on Boiling Heat Transfer of TiO2–Water Nanofluid

2016 ◽  
Vol 138 (8) ◽  
Author(s):  
Cong Qi ◽  
Yongliang Wan ◽  
Lin Liang ◽  
Zhonghao Rao ◽  
Yimin Li
Keyword(s):  
Heat Transfer ◽  
Bubble Size ◽  
Boiling Heat Transfer ◽  
Mass Fraction ◽  
Experimental Methods ◽  
Transfer Coefficients ◽  
Heat Transfer Coefficients ◽  
Mass Fractions ◽  
Boiling Heat Transfer Coefficient ◽  
Bubble Sizes

Considering mass transfer and energy transfer between liquid phase and vapor phase, a mixture model for boiling heat transfer of nanofluid is established. In addition, an experimental installation of boiling heat transfer is built. The boiling heat transfer of TiO2–water nanofluid is investigated by numerical and experimental methods, respectively. Thermal conductivity, viscosity, and boiling bubble size of TiO2–water nanofluid are experimentally investigated, and the effects of different nanoparticle mass fractions, bubble sizes and superheat on boiling heat transfer are also discussed. It is found that the boiling bubble size in TiO2–water nanofluid is only one-third of that in de-ionized water. It is also found that there is a critical nanoparticle mass fraction (wt.% = 2%) between enhancement and degradation for TiO2–water nanofluid. Compared with water, nanofluid enhances the boiling heat transfer coefficient by 77.7% when the nanoparticle mass fraction is lower than 2%, while it reduces the boiling heat transfer by 30.3% when the nanoparticle mass fraction is higher than 2%. The boiling heat transfer coefficients increase with the superheat for water and nanofluid. A mathematic correlation between heat flux and superheat is obtained in this paper.

Effect of CeO2 addition on microstructure and tribological characteristics of laser cladded Cu10Al–MoS2 coating under oil lubrication

2021 ◽  
pp. 146442072110309
Author(s):  
Shao Lifan ◽  
Ge Yuan ◽  
Kong Dejun
Keyword(s):  
Abrasive Wear ◽  
Wear Mechanism ◽  
Mass Fraction ◽  
Friction Reduction ◽  
Depth Of Field ◽  
Oil Lubrication ◽  
Wear Properties ◽  
Fatigue Wear ◽  
Wear Rates ◽  
Mass Fractions

In order to improve the friction and wear properties of Cu10Al–MoS2 coating, the addition of CeO2 is one of the present research hot spots. In this work, Cu10Al–MoS2 coatings with different CeO2 mass fractions were successfully fabricated on Q235 steel using a laser cladding. The microstructure and phase compositions of obtained coatings were analyzed using an ultra-depth of field microscope and X-ray diffraction, respectively. The friction-wear test was carried out under oil lubrication using a ball-on-disk wear tester, and the effects of CeO2 mass fraction on the microstructure, hardness, and friction-wear properties were studied, and the wear mechanism was also discussed. The results show that the laser cladded Cu10Al–MoS2 coatings with the different CeO2 mass fractions were mainly composed of Cu9Al4, Cu, AlFe3, Ni, MoS2, and CeO2 phases. The Vickers-hardness (HV) of Cu10Al–8MoS2–3CeO2, Cu10Al–8MoS2–6CeO2, and Cu10Al–8MoS2–9CeO2 coatings was 418, 445, and 457 HV0.3, respectively, which indicates an increase in hardness with the increase of CeO2 mass fraction. The average coefficients of friction (COF) and wear rates decrease with the increase of CeO2 mass fraction, presenting the outstanding friction reduction and wear resistance performances. The wear mechanism of Cu10Al–MoS2 coatings is changed from abrasive wear with slight fatigue wear to abrasive wear with the increase of CeO2 mass fraction.

scholarly journals Stellar wind effects on the atmospheres of close-in giants: a possible reduction in escape instead of increased erosion

2020 ◽  
Vol 494 (2) ◽  
pp. 2417-2428 ◽  
Author(s):  
A A Vidotto ◽  
A Cleary
Keyword(s):  
Parameter Space ◽  
Stellar Wind ◽  
Planetary Atmospheres ◽  
External Pressure ◽  
Stellar Winds ◽  
Wind Effects ◽  
Atmospheric Escape ◽  
Large Pressure ◽  
Ram Pressure ◽  
Host Stars

ABSTRACT The atmospheres of highly irradiated exoplanets are observed to undergo hydrodynamic escape. However, due to strong pressures, stellar winds can confine planetary atmospheres, reducing their escape. Here, we investigate under which conditions atmospheric escape of close-in giants could be confined by the large pressure of their host star’s winds. For that, we simulate escape in planets at a range of orbital distances ([0.04, 0.14] au), planetary gravities ([36, 87 per cent] of Jupiter’s gravity), and ages ([1, 6.9] Gyr). For each of these simulations, we calculate the ram pressure of these escaping atmospheres and compare them to the expected stellar wind external pressure to determine whether a given atmosphere is confined or not. We show that although younger close-in giants should experience higher levels of atmospheric escape, due to higher stellar irradiation, stellar winds are also stronger at young ages, potentially reducing escape of young exoplanets. Regardless of the age, we also find that there is always a region in our parameter space where atmospheric escape is confined, preferably occurring at higher planetary gravities and orbital distances. We investigate confinement of some known exoplanets and find that the atmosphere of several of them, including π Men c, should be confined by the winds of their host stars, thus potentially preventing escape in highly irradiated planets. Thus, the lack of hydrogen escape recently reported for π Men c could be caused by the stellar wind.

scholarly journals Effects of Plateau Environment on Combustion and Emission Characteristics of a Plateau High-Pressure Common-Rail Diesel Engine with Different Blending Ratios of Biodiesel

Energies ◽  
2022 ◽  
Vol 15 (2) ◽  
pp. 550
Author(s):  
Guohai Jia ◽  
Guoshuai Tian ◽  
Daming Zhang
Keyword(s):  
High Pressure ◽  
Diesel Engine ◽  
Heat Release ◽  
Mass Fraction ◽  
Combustion Temperature ◽  
Common Rail ◽  
Maximum Temperature ◽  
Emission Characteristics ◽  
Mass Fractions ◽  
Maximum Combustion Temperature

Taking a plateau high-pressure common-rail diesel engine as the research model, a model was established and simulated by AVL FIRE according to the structural parameters of a diesel engine. The combustion and emission characteristics of D, B20, and B50 diesel engines were simulated in the plateau atmospheric environment at 0 m, 1000 m, and 2000 m. The calculation results show that as the altitude increased, the peak in-cylinder pressure and the cumulative heat release of diesel decreased with different blending ratios. When the altitude increased by 1000 m, the cumulative heat release was reduced by about 5%. Furthermore, the emission trend of NO, soot, and CO was to first increase and then decrease. As the altitude increased, the mass fraction of NO emission decreased. As the altitude increased, the mass fractions of soot and CO increased. Additionally, when the altitude was 0 m and 1000 m, the maximum temperature, the mass fraction of OH, and the fuel–air ratio of B20 were higher and more uniform. When the altitude was 2000 m, the maximum temperature, the mass fraction of OH, and the fuel–air ratio of B50 were higher and more uniform. Lastly, as the altitude increased, the maximum combustion temperature of D and B20 decreased, and combustion became more uneven. As the altitude increased, the maximum combustion temperature of B50 increased, and the combustion became more uniform. As the altitude increased, the fuel–air ratio and the mass fractions of OH and NO decreased. When the altitude increased, the soot concentration increased, and the distribution area was larger.

scholarly journals Influence of VNIIMK 620 and Itil flax varieties on the rheological properties of wheat dough

2021 ◽  
pp. 33-36
Author(s):  
Tatyana Borisovna Kulevatova ◽  
Lyudmila Nikolaevna Zlobina ◽  
Svetlana Vitalyevna Lyascheva ◽  
Lyubov Vladimirovna Andreeva
Keyword(s):  
Wheat Flour ◽  
Mass Fraction ◽  
Absorption Capacity ◽  
Dispersed Phase ◽  
Rheological Characteristics ◽  
Water Absorption Capacity ◽  
Wheat Dough ◽  
Composite Mixture ◽  
The Stability ◽  
Torque Values

The influence of the mass fraction of flax in the composite mixture on the state of the carbohydrate – amylase complex of the studied system was studied. It was found out that the maximum viscosity of the suspension and the rate of starch gelation in a mixture of wheat flour with whole-ground flax is lower than in the suspension, where the dispersed phase was wheat flour, but higher than that, where the dispersed phase is flax. The influence of flax on the rheological characteristics of wheat dough in the Chopin+ Mixolaba protocol was revealed.  It is found out that with an increase in the mass fraction of flax in the composite mixture from 5 to 20%, the formation time of the test and its water absorption capacity increases, and the stability decreases. When the mass fraction of flax increases, the torque values at the extreme point of the function C2, which characterizes the dilution of the dough, increase; and at the point C5, which characterizes the retrogradation of starch, they decrease.  

scholarly journals The study of the properties of sweet cream butter with flavoring components

2018 ◽  
Vol 80 (3) ◽  
pp. 220-223
Author(s):  
O. I. Dolmatova ◽  
A. S. Sharshov
Keyword(s):  
Shelf Life ◽  
Mass Fraction ◽  
Maple Syrup ◽  
Warranty Period ◽  
Fatty Oil ◽  
Organoleptic Characteristics ◽  
Good Consistency ◽  
Microbiological Parameters ◽  
The Stability ◽  
Time Reserve

The technology of sweet-sour dessert oil with maple syrup has been developed. It is of scientific interest to study its quality indices when stored. The organoleptic characteristics of the butter of the sweetener with flavor components were determined in the scores. The score of the ball was 20 points. The chemical parameters of sweet dessert oil with maple syrup are found: mass fraction of fat, not less than – 62%, mass fraction of dry substances, not less – 9,5%, mass fraction of moisture, not more than – 28,5%. The conformity of oil indicators with the norms specified in TP TS 033/2013 for cream butter with the components is established: mass fraction of fat – 50 to 69%, mass fraction of moisture – 16 to 45%. The thermostability of butter of sweet-dessert dessert oil with maple syrup has been determined – 0,7, i.e. the indicator is characterized as satisfactory. A good consistency of sweet dessert oil with maple syrup is found on the slice – the plate has a dense, even surface and edges, with slight pressure bending. The shelf life of sweet dessert oil with maple syrup is 15 days. Acidity of the fat phase was determined over a period of 21 days (taking into account the time reserve). The index of acidity of the analyzed sample for 15 days was – 2.7 °C, which corresponds to the norm. Estimation of the acidity of the fatty phase and the acidity of the plasma of the oil showed an insignificant increase during the warranty period of shelf life. The stability of fatty oil of sweet-dessert dessert with maple syrup has been determined. During the experiment, the color became yellow, the smell is sweet, creamy, pleasant, the aroma of maple syrup is pronounced. The specimen withstood the test for 8 hours, no damage to the fat is noted. The microbiological parameters of the oil have been determined. The conformity of oil with the requirements of State standard 32899–2014 and TP TS 033/2013 during storage is established.

scholarly journals TOXIC ELEMENTS IN LENTIL, THYME AND JUNIPER IN THE COMPOSITION OF SEMI-SMOKED SAUSAGES USING THE METHOD OF ATOMIC-ABSORPTION SPECTROMETRY WITH ATOMIZATION IN FLAME

2017 ◽  
Vol 4 ◽  
pp. 35-42 ◽  
Author(s):  
Maria Paska ◽  
Iryna Simonova ◽  
Bogdan Galuch ◽  
Iryna Basarab ◽  
Olga Masliichuk
Keyword(s):  
Mass Fraction ◽  
Toxic Elements ◽  
Raw Materials ◽  
Absorption Spectrometry ◽  
Resonance Absorption ◽  
Selective Absorption ◽  
Analytical Wavelength ◽  
Mass Fractions ◽  
Calibration Dependence ◽  
Vegetable Raw Materials

Studies have been conducted into the content of toxic elements in sprouted and unsprouted lentils, juniper fruits and thyme herb, manufactured samples of semi-smoked sausages whose formulation contained the specified ingredients. The samples were prepared for conducting the study. Measuring the mass fraction of heavy metals is based on the selective absorption of electromagnetic radiation of a certain frequency by atoms of substance in a free state. Metal mass fraction in the mineralizate of a sample of food products was calculated by the calibration dependence of absorption magnitude on mass concentration of the metal. Measurement of copper and zinc mass fractions involved an atomization technique in the air-acetylene flame, with a burner heated to a temperature of around 3000 °C; their content was determined by the magnitude of radiation resonance absorption at analytical wavelength corresponding to the examined metal. It was determined that the investigated vegetable raw materials and semi-smoked sausages did not contain toxic elements that exceeded the standard.

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