scholarly journals A Semi-Theoretical Model for Water Condensation: Dew Used in Conservation of Earthen Heritage Sites

Water ◽  
2020 ◽  
Vol 13 (1) ◽  
pp. 52
Author(s):  
Xiang He ◽  
Sijia Wang ◽  
Bingjian Zhang
Keyword(s):  
Mass Transfer ◽  
Theoretical Model ◽  
Field Experiments ◽  
Environmental Control ◽  
Mass Transfer Process ◽  
Formation Processes ◽  
Heritage Sites ◽  
Dew Formation ◽  
The Difference ◽  
Two Parameter

Dew is a common but important phenomenon. Though water is previously considered to be a threat to earthen heritage sites, artificial dew is showing potential in relic preservation. A model of dew prediction on earthen sites will be essential for developing preventive protection methods, but studies of dew formation processes on relics are limited. In this study, a two parameter model is proposed. It makes approximations according to the features of earthen heritage sites, assuming that a thin and steady air layer exists close to the air–solid interface. This semi-theoretical model was based on calculations of the mass transfer process in the air layer, and was validated by simulations of laboratory experiments (R > 0.9) as well as field experiments. Additionally, a numerical simulation, performed by the commercial software COMSOL, confirmed that the difference between fitting parameter δ and the thickness of assumed mass transfer field was not significant. This model will be helpful in developing automatic environmental control systems for stabilizing water and soluble salts, thus enhancing preventive protection of earthen heritage sites.

scholarly journals Modeling of Catalytic Centers Formation Processes during Annealing of Multilayer Nanosized Metal Films for Carbon Nanotubes Growth

Nanomaterials ◽  
2020 ◽  
Vol 10 (3) ◽  
pp. 554
Author(s):  
Oleg Il’in ◽  
Nikolay Rudyk ◽  
Alexandr Fedotov ◽  
Marina Il’ina ◽  
Dmitriy Cherednichenko ◽  
...  
Keyword(s):  
Carbon Nanotubes ◽  
Mass Transfer ◽  
Chemical Potential ◽  
Stress Gradient ◽  
Metal Films ◽  
Film Structure ◽  
Formation Processes ◽  
Thermal Expansion Coefficients ◽  
Mass Transfer Processes ◽  
The Difference

The paper presents a theoretical model of the catalytic centers formation processes during annealing of multilayer nanosized metal films for carbon nanotubes growth. The approach to the description of the model is based on the mass transfer processes under the influence of mechanical thermoelastic stresses, which arise due to the difference in the thermal expansion coefficients of the substrate materials and nanosized metal layers. The thermal stress gradient resulting from annealing creates a drop in the chemical potential over the thickness of the film structure. This leads to the initiation of diffusion mass transfer between the inner and outer surfaces of the films. As a result, the outer surface begins to corrugate and fragment, creating separate islands, which serve as the basis for the catalytic centers formation. Experimental research on the formation of catalytic centers in the structure of Ni/Cr/Si was carried out. It is demonstrated that the proposed model allows to predict the geometric dimensions of the catalytic centers before growing carbon nanotubes. The results can be used to create micro- and nanoelectronics devices based on carbon nanotube arrays.

I Like Her, Because I Like Myself: Self-Evaluation as a Source of Interpersonal Attitudes

2003 ◽  
Vol 50 (4) ◽  
pp. 239-246 ◽  
Author(s):  
Eva Walther ◽  
Claudia Trasselli
Keyword(s):  
Opposite Effect ◽  
Learning Phase ◽  
The Self ◽  
Attitude Formation ◽  
Formation Processes ◽  
False Feedback ◽  
Self Evaluation ◽  
Evaluation Group ◽  
Group A ◽  
The Difference

Abstract. Two experiments tested the hypothesis that self-evaluation can serve as a source of interpersonal attitudes. In the first study, self-evaluation was manipulated by means of false feedback. A subsequent learning phase demonstrated that the co-occurrence of the self with another individual influenced the evaluation of this previously neutral target. Whereas evaluative self-target similarity increased under conditions of negative self-evaluation, an opposite effect emerged in the positive self-evaluation group. A second study replicated these findings and showed that the difference between positive and negative self-evaluation conditions disappeared when a load manipulation was applied. The implications of self-evaluation for attitude formation processes are discussed.

A Theoretical Model for Unsteady Coupled Heat and Mass Transfer Phenomena in Industrial Dryers

2011 ◽  
Vol 42 (5) ◽  
pp. 415-432
Author(s):  
Hossein Shokouhmand ◽  
Sajjad Bigham ◽  
Sajjad Yazdani
Keyword(s):  
Mass Transfer ◽  
Theoretical Model ◽  
Heat And Mass Transfer

THE INFLUENCE OF TILLAGE SYSTEMS ON THE GROWTH, DEVELOPMENT AND YIELD OF LONG-FLAX

2020 ◽  
Author(s):  
V. Dumych ◽  
Keyword(s):  
Growth And Development ◽  
Field Experiments ◽  
Conservation Tillage ◽  
Mineral Fertilizers ◽  
Tillage Systems ◽  
Yield And Quality ◽  
Tillage System ◽  
The Difference ◽  
Flax Seeds

The purpose of research: to improve the technology of growing flax in the Western region of Ukraine on the basis of the introduction of systems for minimizing tillage, which will increase the yield of trusts and seeds. Research methods: field, laboratory, visual and comparative calculation method. Research results: Field experiments included the study of three tillage systems (traditional, canning and mulching) and determining their impact on growth and development and yields of trusts and flax seeds. The traditional tillage system included the following operations: plowing with a reversible plow to a depth of 27 cm, cultivation with simultaneous harrowing and pre-sowing tillage. The conservation system is based on deep shelfless loosening of the soil and provided for chiseling to a depth of 40 cm, disking to a depth of 15 cm, cultivation with simultaneous harrowing, pre-sowing tillage. During the implementation of the mulching system, disking to a depth of 15 cm, cultivation with simultaneous harrowing and pre-sowing tillage with a combined unit was carried out. Tillage implements and machines were used to perform tillage operations: disc harrow BDVP-3,6, reversible plow PON-5/4, chisel PCh-3, cultivator KPSP-4, pre-sowing tillage unit LK-4. The SZ-3,6 ASTPA grain seeder was used for sowing long flax of the Kamenyar variety. Simultaneously with the sowing of flax seeds, local application of mineral fertilizers (nitroammophoska 2 c/ha) was carried out. The application of conservation tillage allows to obtain the yield of flax trust at the level of 3,5 t/ha, which is 0,4 t/ha (12.9 %) more than from the area of traditional tillage and 0,7 t/ha (25 %) in comparison with mulching. In the area with canning treatment, the seed yield was the highest and amounted to 0,64 t/ha. The difference between this option and traditional and mulching tillage reaches 0,06 t/ha (10,3 %) and 0.10 t/ha (18.5 %), respectively. Conclusions. Preservation tillage, which is based on shelf-free tillage to a depth of 40 cm and disking to a depth of 15 cm has a positive effect on plant growth and development, yield and quality of flax.

Analysis and calculation of the process of low-pressure reverse osmosis during recycling of hygienic water

2019 ◽  
pp. 28-36
Author(s):  
Leonid S. Bobe ◽  
Nikolay A. Salnikov
Keyword(s):  
Mass Transfer ◽  
Reverse Osmosis ◽  
Life Support ◽  
Space Station ◽  
Low Pressure ◽  
Operating Pressure ◽  
Life Support System ◽  
Cleaning Agent ◽  
The Difference ◽  
Pressure Channel

Analysis and calculation have been conducted of the process of low-pressure reverse osmosis in the membrane apparatus of the system for recycling hygiene water for the space station. The paper describes the physics of the reverse osmosis treatment and determines the motive force of the process, which is the difference of effective pressures (operating pressure minus osmotic pressure) in the solution near the surface of the membrane and in the purified water. It is demonstrated that the membrane scrubbing action is accompanied by diffusion outflow of the cleaning agent components away from the membrane. The mass transfer coefficient and the difference of concentrations (and, accordingly, the difference of osmotic pressures) in the boundary layer of the pressure channel can be determined using an extended analogy between mass transfer and heat transfer. A procedure has been proposed and proven in an experiment for calculating the throughput of a reverse osmosis apparatus purifying the hygiene water obtained through the use of a cleaning agent used in sanitation and housekeeping procedures on Earth. Key words: life support system, hygiene water, water processing, low-pressure reverse osmosis, space station.

Simulation of volumetric heating of a moist medium with allowance for fluid mobility

2012 ◽  
Vol 9 (1) ◽  
pp. 91-93
Author(s):  
U.R. Ilyasov ◽  
A.V. Dolgushev
Keyword(s):  
Mass Transfer ◽  
Porous Medium ◽  
Numerical Solution ◽  
Heat And Mass Transfer ◽  
Transfer Process ◽  
Thermal Action ◽  
Mass Transfer Process ◽  
Low Permeability ◽  
Volumetric Heating ◽  
Drying Regime

The problem of volumetric thermal action on a moist porous medium is considered. Numerical solution, the influence of fluid mobility on the dynamics of the heat and mass transfer process is analyzed. It is established that fluid mobility leads to a softer drying regime. It is shown that in low-permeability media, the fluid can be assumed to be stationary.

Possible application of approximate models for calculation of selectivity of consecutive reactions under the effect of mass transfer

1982 ◽  
Vol 47 (5) ◽  
pp. 1301-1309 ◽  
Author(s):  
František Kaštánek ◽  
Marie Fialová
Keyword(s):  
Mass Transfer ◽  
Numerical Method ◽  
Analytical Method ◽  
Approximate Analytical Method ◽  
Approximate Models ◽  
Consecutive Reactions ◽  
The Difference

The possibility of use of approximate models for calculation of selectivity of consecutive reactions is critically analysed. Simple empirical criteria are proposed which enable safer application of approximate analytical reactions. A more universal modification has been formulated by use of which the difference of selectivity calculated by the exact numerical method and by the approximate analytical method is at maximum 12%.

Free Convective Mass Transfer at Isosceles Triangular Surfaces of Varying Inclination

2003 ◽  
Vol 68 (11) ◽  
pp. 2080-2092 ◽  
Author(s):  
Martin Keppert ◽  
Josef Krýsa ◽  
Anthony A. Wragg
Keyword(s):  
Mass Transfer ◽  
Transfer Rate ◽  
Mass Transfer Rate ◽  
Mass Transfer Process ◽  
Sulfate Solution ◽  
Convective Mass Transfer ◽  
Varying Length ◽  
Inclined Surface ◽  
Vertical Case ◽  
Limiting Diffusion Current

The limiting diffusion current technique was used for investigation of free convective mass transfer at down-pointing up-facing isosceles triangular surfaces of varying length and inclination. As the mass transfer process, copper deposition from acidified copper(II) sulfate solution was used. It was found that the mass transfer rate increases with inclination from the vertical to the horizontal position and decreases with length of inclined surface. Correlation equations for 7 angles from 0 to 90° were found. The exponent in the ShL-RaL correlation ranged from 0.247 for the vertical case, indicating laminar flow, to 0.32 for inclinations of 60 to 90°, indicating mixed or turbulent flow. The general correlation ShL = 0.358(RaL sin θ)0.30 for the RaL sin θ range from 7 × 106 to 2 × 1011 and inclination range from 15 to 90° was obtained.

Multilevel cross flow rotating packed bed to enhance gas film control mass transfer process

2021 ◽  
Vol 161 ◽  
pp. 108321
Author(s):  
Qing-Qing Duan ◽  
Zhi-Guo Yuan ◽  
You-Zhi Liu ◽  
Shan-Shan Duan ◽  
Xi-Fan Duan
Keyword(s):  
Mass Transfer ◽  
Transfer Process ◽  
Cross Flow ◽  
Mass Transfer Process ◽  
Packed Bed ◽  
Rotating Packed Bed
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