Simulation of nuclear-physical processes in the surface layer of a fuel kernel with a consumable absorber

In oceanic gyres, primary producers are numerically dominated by small (1-5 µm diameter) pro- and eukaryotic cells that primarily utilize recycled nutrients produced by rapid grazing turnover in a highly efficient microbial loop. Continuous losses of nitrogen to depth by sinking, either as single cells, aggregates or fecal pellets, are balanced by both nitrate inputs at the base of the euphotic zone and nitrogen-fixation. This input of N (new nitrogen) to balance export losses (the biological pump) is a fundamental aspect of nitrogen cycling and central to understanding carbon fluxes in the ocean. In the Pacific Ocean, detailed nitrogen budgets at the time-series station HOT require upward transport of nitrate from the nutricline (80-100 m) into the surface layer (~0-40 m) to balance productivity and export needs. However, concentration gradients are negligible and cannot support the fluxes. Physical processes can inject nitrate into the base of the euphotic zone, but the mechanisms for transporting this nitrate into the surface layer across many 10s of m in highly stratified systems are unknown. In these seas, vertical migration by the very largest 102-103 µm diameter) phytoplankton is common as a survival strategy to obtain nitrogen from sub-euphotic zone depths. This vertical migration is driven by buoyancy changes rather than by flagellated movement and can provide upward nitrogen transport as nitrate (mM concentrations) in the cells. However, the contribution of vertical migration to nitrate transport has been difficult to quantify over the required basin scales. In this study, we use towed optical systems and isotopic tracers to show that migrating diatom (Rhizosolenia) mats are widespread in the N. Pacific Ocean from 140°W to 175°E and together with other migrating phytoplankton (Ethmodiscus, Halosphaera, Pyrocystis, and solitary Rhizosolenia) can mediate time-averaged transport of N (235 µmol N m-2 d-1) equivalent to eddy nitrate injections (242 µmol NO3- m-2 d-1). This upward biotic transport can close nitrate budgets in the upper 250 m of the central Pacific Ocean and together with diazotrophy creates a surface zone where biological nutrient inputs rather than physical processes dominate the new N flux. In addition to these numerically rare large migrators, there is extensive evidence in the literature of ascending behavior in small phytoplankton that contributes to upward flux as well. Although passive downward movement has dominated models of phytoplankton flux, there is now sufficient evidence to require a rethinking of this paradigm. Quantifying these fluxes is a challenge for the future and requires a reexamination of individual phytoplankton sinking rates as well as methods for capturing and enumerating ascending phytoplankton in the sea.

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Coupling and decoupling processes in monsoonal surface layer using MONTBLEX-90 tower data

MAUSAM ◽

10.54302/mausam.v48i3.4266 ◽

2021 ◽

Vol 48 (3) ◽

pp. 375-384

Author(s):

T.N. JHA ◽

K. C. SINHA RAY ◽

H. N. SRIVASTAVA

Keyword(s):

Surface Layer ◽

Eddy Viscosity ◽

Surface Soil ◽

Turbulent Transfer ◽

Bulk Richardson Number ◽

Physical Processes ◽

Stable Case ◽

Class A ◽

Order Of Magnitude ◽

Surface Soil Temperature

ABSTRACT. MONI'BLEX-90 data of Varanasi and Jodhpur have been used to study the physical processes in the surface layer. The results show that turbulent transfer of heat, momentum and moisture commence at an average eddy viscosity of an order of magnitude 5.13 × 10-1 J -s kg-1 during rainy day. In absolutely stable case, eddy viscosity may be equal to 4.94 × 10-4 J-s kg-1 or less to decouple surface layer from rest of the planetary boundary layer for extinction of the turbulent transfer of fluxes. These results were based on 8m and 15m meteorological tower observations and surface soil temperature using analytical solution of Byun (1990) and K theory. It was found that the surface layer is decoupled only in case of stability of Class - A because bulk Richardson number is greater than zero and corresponding stability parameter is positive.

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NANOSTRUCTURES IN THE THIN LAYER OF COAL SUBSTANCE

Physical and Chemical Aspects of the Study of Clusters Nanostructures and Nanomaterials ◽

10.26456/pcascnn/2020.12.746 ◽

2020 ◽

pp. 746-757

Author(s):

Виктор Михайлович Юров ◽

Канат Мэтович Маханов ◽

Василий Сергеевич Портнов

Keyword(s):

Surface Layer ◽

Thin Layer ◽

Supramolecular Structure ◽

Explosion Hazard ◽

Physical Processes ◽

Pure Metals ◽

Bulk Structure ◽

Structure Lead

В представленной работе рассмотрен поверхностный слой угольного вещества, структура и характеристики которого отличны от структуры объема. Этот слой имеет два уровня: d(I) равный 151,5 нм и d(II)≈10 ⋅ d равный 1515 нм для антрацита. Для чистых металлов d(I) равно 1 - 6 нм, что на 2 порядка меньше поверхностного слоя угольного вещества. Толщина этого слоя имеет порядок толщин высших фуллеренов С, равного 135 нм. Все эти особенности угольного вещества, имеющего углеродную основу и представляющего собой полимер с надмолекулярной структурой, приводят к тому, что именно поверхностный слой определяет физические процессы в нем, связанные с протеканием газов и жидкости, а также с явлениями взрывоопасности. In the present work, the surface layer of a coal substance is considered, the structure and characteristics of which are different from the bulk structure. This layer has two levels: d (I) equal to 151,5 nm and d(II) ≈ 10 ⋅ d equal to 1515 nm for anthracite. For pure metals d(I) is equal 1 - 6 nm, that is 2 orders of magnitude lesser than the surface layer of the coal substance. The thickness of this layer is of the order of 135 nm for the higher C fullerenes. All these features of a coal substance, which has a carbon base and is a polymer with a supramolecular structure, lead to the fact that it is the surface layer that determines the physical processes in it associated with the flow of gases and liquids, as well as with the phenomena of the explosion hazard.

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Contribution of extreme meteorological forcing to vertical mixing in a small, shallow subtropical lake

Journal of Limnology ◽

10.4081/jlimnol.2016.1477 ◽

2016 ◽

Cited By ~ 1

Author(s):

Nobuaki Kimura ◽

Wen-Cheng Liu ◽

Jeng-Wei Tsai ◽

Chih-Yu Chiu ◽

Timothy K. Kratz ◽

...

Keyword(s):

Surface Layer ◽

Heavy Rainfall ◽

Vertical Mixing ◽

Heat Content ◽

Extreme Weather Events ◽

Heavy Rainfall Event ◽

Physical Factors ◽

Physical Processes ◽

Meteorological Forcing ◽

Stratified Lake

Studying mixing processes in a stratified lake is important for understanding the biological, chemical and physical processes occurring there. Statistical analyses were performed of data from a small, shallow, stratified lake in a subtropical alpine region (Yuan-Yang Lake in Taiwan) to determine the predominant physical factors in heavy-rainfall-induced mixing. This study focused on both vertical mixing in the entire water column and surface-layer mixing extending to the upper thermocline. The effects of meteorological driving forces, such as wind, heating/cooling and inflow on vertical mixing and surface layer mixing, were evaluated using the relationships between each driving force and the change in thermal stability between the pre-mixing and mixing periods. For surface layer mixing, a comparison between penetrative convection related to heating/cooling and wind-related friction velocity was conducted for each heavy rainfall event. A heat content parameter measuring thermal potential energy was introduced to further investigate inflow effects (e.g. effects of changes in discharge volume and temperature) on vertical mixing during heavy rainfall events. Results show that wind input affected vertical mixing more significantly than did other meteorological forcing factors during storm-dominant events. Indeed, wind energy input in the surface layer was more pronounced than was energy of heating/cooling for surface layer mixing. Furthermore, inflow effect was shown to be crucial during large scale and extreme weather events (i.e. lower air pressure events) in the vertical mixing process. Forcing by heating/cooling likely contributes less to mixing because it is likely less dynamic than the wind and inflow inputs with respect to internal response of the lake. In addition, a principal component analysis (PCA) modified by partial correlation was performed to verify the results quantitatively. The first and second components, which accounted for more than 90% of the total variance in the PCA, showed that the intensity of vertical mixing was affected primarily by wind-induced turbulence and inflow intrusion and was only weakly associated with the effect of net heat balance. Considering the interactions between chemical and physical processes, inflow intrusion may have an effect on dissolved oxygen concentration in the lake.

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Refraction in bilateral trigonometric leveling. Defi nition of corrections

Geodesy and Cartography ◽

10.22389/0016-7126-2018-934-4-8-13 ◽

2018 ◽

Vol 934 (4) ◽

pp. 8-13 ◽

Cited By ~ 1

Author(s):

O.A. Mozzhukhin

Keyword(s):

Surface Layer ◽

Thermal Stratification ◽

Modeling Method ◽

The State ◽

Optical Beam ◽

Practical Application ◽

Physical Processes ◽

Atmospheric Refraction ◽

Geodetic Measurements

The practical application of bilateral trigonometric leveling in geodetic measurements is limited by the effect of atmospheric refraction. If this effect is eliminated, the accuracy of bilateral measurements can be comparable to the results of precise geometric leveling. By applying the similarity and modeling method to the problem of accounting for refraction in leveling and also taking into account the conditions of interaction of the optical beam with the physical processes taking place in the surface layer, these limitations can be minimized. The solution of the problem of determining corrections due to the influence of refraction in bilateral trigonometric leveling by simulation of the quantities participating in the process, obtained through joint geodetic and meteorological measurements, as well as the main provisions – in unilateral leveling, which are the basis for the method of bilateral measurements. Practical examples show the features of calculation of corrections, depending on the state of thermal stratification of the surface layer of the atmosphere.

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Upward nitrate transport by phytoplankton in oceanic waters: balancing nutrient budgets in oligotrophic seas

10.7287/peerj.preprints.189 ◽

2014 ◽

Author(s):

Tracy A Villareal ◽

Cynthia H. Pilskaln ◽

Joseph P. Montoya ◽

Mark Dennett

Keyword(s):

Surface Layer ◽

Pacific Ocean ◽

Vertical Migration ◽

Euphotic Zone ◽

Optical Systems ◽

Fundamental Aspect ◽

Sufficient Evidence ◽

Nitrate Transport ◽

Physical Processes ◽

Isotopic Tracers

In oceanic gyres, primary producers are numerically dominated by small (1-5 µm diameter) pro- and eukaryotic cells that primarily utilize recycled nutrients produced by rapid grazing turnover in a highly efficient microbial loop. Continuous losses of nitrogen to depth by sinking, either as single cells, aggregates or fecal pellets, are balanced by both nitrate inputs at the base of the euphotic zone and nitrogen-fixation. This input of N (new nitrogen) to balance export losses (the biological pump) is a fundamental aspect of nitrogen cycling and central to understanding carbon fluxes in the ocean. In the Pacific Ocean, detailed nitrogen budgets at the time-series station HOT require upward transport of nitrate from the nutricline (80-100 m) into the surface layer (~0-40 m) to balance productivity and export needs. However, concentration gradients are negligible and cannot support the fluxes. Physical processes can inject nitrate into the base of the euphotic zone, but the mechanisms for transporting this nitrate into the surface layer across many 10s of m in highly stratified systems are unknown. In these seas, vertical migration by the very largest 102-103 µm diameter) phytoplankton is common as a survival strategy to obtain nitrogen from sub-euphotic zone depths. This vertical migration is driven by buoyancy changes rather than by flagellated movement and can provide upward nitrogen transport as nitrate (mM concentrations) in the cells. However, the contribution of vertical migration to nitrate transport has been difficult to quantify over the required basin scales. In this study, we use towed optical systems and isotopic tracers to show that migrating diatom (Rhizosolenia) mats are widespread in the N. Pacific Ocean from 140°W to 175°E and together with other migrating phytoplankton (Ethmodiscus, Halosphaera, Pyrocystis, and solitary Rhizosolenia) can mediate time-averaged transport of N (235 µmol N m-2 d-1) equivalent to eddy nitrate injections (242 µmol NO3- m-2 d-1). This upward biotic transport can close nitrate budgets in the upper 250 m of the central Pacific Ocean and together with diazotrophy creates a surface zone where biological nutrient inputs rather than physical processes dominate the new N flux. In addition to these numerically rare large migrators, there is extensive evidence in the literature of ascending behavior in small phytoplankton that contributes to upward flux as well. Although passive downward movement has dominated models of phytoplankton flux, there is now sufficient evidence to require a rethinking of this paradigm. Quantifying these fluxes is a challenge for the future and requires a reexamination of individual phytoplankton sinking rates as well as methods for capturing and enumerating ascending phytoplankton in the sea.

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Numerical Simulation of Thermal Physical Processes During Surface Layer Modification in Metal Subjected to Induction Heating

Herald of the Bauman Moscow State Technical University Series Mechanical Engineering ◽

10.18698/0236-3941-2018-2-114-125 ◽

2018 ◽

Author(s):

В.Н. Попов ◽

◽

В.Г. Щукин ◽

О.А. Бойко ◽

◽

...

Keyword(s):

Numerical Simulation ◽

Surface Layer ◽

Induction Heating ◽

Physical Processes

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ESTIMATION OF THE CHANGE FROME HEIGHT OF THE VERTICAL AIR FLOW IN THE SURFACE LAYER OF THE ATMOSPHERE FOR A REGIME CLOSE TO THE ‘PURE CONVECTION’ REGIME

National Association of Scientists ◽

10.31618/nas.2413-5291.2020.2.59.292 ◽

2020 ◽

Vol 2 (32(59)) ◽

pp. 13-17

Author(s):

B. Kantsyrev

Keyword(s):

Surface Layer ◽

Water Vapor ◽

Air Temperature ◽

Mass Fraction ◽

Continuity Equation ◽

Asymptotic Form ◽

Universal Functions ◽

Physical Processes ◽

Convection Regime ◽

One Dimensional

The purpose of this work is to analyze and concretize the asymptotic form of writing the continuity equation [3] for modeling thermo-physical processes in the surface layer of the atmosphere. In this case, the solution of the system of spatially one-dimensional equations of conservation laws for vertical dependences of air temperature and mass fraction of water vapor can be obtained in the future by using the calculated empirical dependences for the coefficient of turbulent exchange, based on the Monin-Obukhov “universal functions” approach.

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