scholarly journals DYNAMICS OF THE OCCUPATION OF THE NIGERRIVERBED IN NIAMEY

2021 ◽  
Vol 9 (11) ◽  
pp. 649-655
Author(s):  
Tahirou Hassane Yaou ◽  
◽  
Abdoulkader Moussa Issaka ◽  
Bouba Hassane ◽  
Amadou Abdourhamane Toure ◽  
...  
Keyword(s):  
Surface Area ◽  
Satellite Images ◽  
Area Increase ◽  
Irrigated Crops ◽  
Surface Area Increase

The objective of this study is to analyze the dynamics of the Niger riverbed occupationin Niamey. The methodology used is based on the processing of satellite images and their interpretation. The results showed, between 1973 and 2018, a reduction of the free riverbed (from 2415.28 ha in 1973 to 1952.88 ha in 2018 i.e. a regression of 29.91 ha) following its progressive occupation by irrigated crops, dwellings and islands, of about 10.27 ha/year. The islands surface area increase reflects the silting of the river. This silting up causes the river to overflow and worsens flooding.

scholarly journals Pre-Treatment Methods for Regeneration of Spent Activated Carbon

Molecules ◽  
2020 ◽  
Vol 25 (19) ◽  
pp. 4561
Author(s):  
Sang Youp Hwang ◽  
Gi Bbum Lee ◽  
Ji Hyun Kim ◽  
Bum Ui Hong ◽  
Jung Eun Park
Keyword(s):  
Activated Carbon ◽  
Surface Area ◽  
Acid Treatment ◽  
Chemical Activation ◽  
Fixed Carbon ◽  
Treatment Methods ◽  
Positive Effects ◽  
Area Increase ◽  
Pre Treatment ◽  
Surface Area Increase

Spent activated carbon (SAC) usually exhibits a low specific surface area due to its high ash contents. In this study, pre-treatments, such as heat and acid treatments, were optimized to improve this feature. The heat pre-treatment did not reduce the ash content, nor did it increase the surface area. Because metallic ions adsorbed in SACs turn into ash upon the heat treatment. In the acid pre-treatment, the volatiles and fixed carbon were increased with decreasing ash contents. In this study, it was found that the surface area increase was correlated with the ratio between fixed carbon and ash. Among the pre-treatment methods, the combined heat and acid pre-treatment method highly increased the ratio, and therefore led to the surface area increase. Additionally, the acid pre-treatment was carried out using different types of acid (organic and inorganic acids) solutions to further improve the surface areas. The organic acid treatment caused a significant structural collapse compared to the inorganic acid treatment, decreasing the surface area. In particular, H3PO4 effectively removed ashes adsorbed on the activated carbon surface and regenerated the exhausted activated carbon. Both the heat and acid pre-treatments before chemical activation resulted in the positive effects such as strong desorption of pollutants and ashes within the internal structure of the activated carbon. Therefore, the regeneration introduced in this study is methodically the best method to regenerate SAC and maintain a stable structure.

scholarly journals Secondary Atomization of a Biodiesel Micro-Emulsion Fuel Droplet Colliding with a Heated Wall

2020 ◽  
Vol 10 (2) ◽  
pp. 685 ◽  
Author(s):  
Alexander E. Ashikhmin ◽  
Nikita A. Khomutov ◽  
Maxim V. Piskunov ◽  
Vyacheslav A. Yanovsky
Keyword(s):  
Surface Area ◽  
High Speed ◽  
Heating Temperature ◽  
Video Recording ◽  
Heated Wall ◽  
Fuel Droplet ◽  
Area Increase ◽  
Micro Emulsion ◽  
2D And 3D ◽  
Surface Area Increase

Using high-speed video recording, we establish the following regimes of hydrodynamic interaction of a biodiesel micro-emulsion fuel droplet with a heated wall: deposition (including drop spreading and receding), drop hydrodynamic breakup, and rebound. Collision regime maps are plotted using a set of dimensionless criteria: Weber number We = 470–1260, Ohnesorge number Oh = 0.146–0.192, and Reynolds number Re = 25–198. The scenarios of droplet hydrodynamic disintegration are studied for transient and film boiling. We also estimate the disintegration characteristics of a biodiesel micro-emulsion droplet (mean diameter of child droplets, their number, and evaporation surface area increase due to breakup). The study establishes the effect of water proportion on the micro-emulsion composition (8–16 vol.%), heating temperature (300–500 °C), droplet size (1.8–2.8 mm), droplet velocity (3–4 m/s), rheological properties of the examined compositions, and emulsifier concentration (10.45 vol.% and 20 vol.%) on the recorded characteristics. The results show that the initial liquid surface area can be increased 2–19 times. The paper analyzes ways to control the process. The hydrodynamic disintegration characteristics of a biodiesel micro-emulsion fuel droplet are compared using 2D and 3D recording.

A Comparison of Methods for Determining Surface Areas of Carbon Black

1973 ◽  
Vol 46 (1) ◽  
pp. 192-203 ◽  
Author(s):  
R. A. Klyne ◽  
B. D. Simpson ◽  
M. L. Studebaker
Keyword(s):  
Carbon Black ◽  
Specific Surface ◽  
Surface Area ◽  
Specific Surface Area ◽  
Surface Areas ◽  
Furnace Black ◽  
Area Increase ◽  
Experimental Errors ◽  
Specific Surface Areas ◽  
Surface Area Increase

Abstract 1. The various tint tests correlate with each other—it does not make much difference which of the three procedures is used. The discrimination between similar blacks is comparable. Specific surface areas obtained by the three methods are comparable and differences appear to be due to experimental errors. (Compare Figures 5–7). 2. Surface areas larger than some 90 to 100 m2/g cannot be reliably determined from tint strength measurements alone. 3. Structure exerts a pronounced effect on tint strength of furnace blacks, especially above 90 to 100 m2/g. Porosity and/or composition are apparently also variables which affect tinting strength. 4. Densichron reflectance on the dry carbon black can be used to estimate specific surface areas up to about 140 m2/g; but, since theabsoluteerrorincreases as the specific surface area increases, this method loses some of its reliability at values above about 110 m2/g. The relative error in reflectance determinations does not vary greatly over the furnace-black range. Densichron reflectance is influenced by composition, evidently due to composition-related differences in optical properties of the carbons. 5. In CTAB adsorption measurements, titration errors and handling errors tend to be rather constant for blacks of different surface area. Hence, CTAB permits better discrimination among blacks of small particle size. 6. The errors in Densichron reflectance surface area increase with specific surface area. Hence, the deviations between CTAB and reflectance surface area which are due to experimental error increase with the surface area of the sample.

scholarly journals Studying coefficient of increase of the support surface after deployment of a mobile hoist

2021 ◽  
pp. 26
Author(s):  
Igor Kyrychenko ◽  
Oleksandr Rieznikov ◽  
Yuri Rukavishnikov ◽  
Anton Knyshenko
Keyword(s):  
Surface Area ◽  
Computer Technology ◽  
Design Stage ◽  
Geometrical Parameters ◽  
Support Surface ◽  
Area Increase ◽  
Different Types ◽  
Support Device ◽  
Surface Area Increase ◽  
Support Devices

Currently, there are about 150 manufacturers of mobile elevating work platforms (MEWP), which are constantly designing and implementing new machines with advanced capabilities. Along with the improvement of hoisting equipment, the support devices of the MEWP are also improved. Therefore, there is a need to investigate the coefficient of increase of the support surface area after the deployment of a mobile hoist for different types of support devices. Goal. The aim of this work is to study how the coefficient of increase of the support surface area after the deployment of the support device depends on the length of the support projecting for different designs of support devices used in MEWP. Methodology. Analytical methods of studying the designs with variable geometrical parameters were used in the work. To obtain the dependences of the coefficient of increase of the support surface area after the deployment of the support device on the length of the support projecting, the methods of mathematical modeling employing computer technology were used. Results. The analysis of the dependences of the coefficient of the support surface area increase after the deployment of the support device on the length of the support projecting showed that the use of the considered support devices enlarges the coefficient of increase of the support surface area from 1.9 with angular supports to 3.4 for Spider type support devices. Originality. It is proposed to consider the coefficient of increase of the support surface area, which enables to take into account the lengths and angles of the supports when determining the support surface area. Practical value. With the results of the study it is possible to choose the type of support device and its geometric parameters at the design stage which will

Influence of high pressure on texture of carbonaceous substances

1983 ◽  
Vol 48 (1) ◽  
pp. 26-33 ◽  
Author(s):  
Jiří Medek ◽  
Ivan Mohyla
Keyword(s):  
Electron Microscopy ◽  
High Pressure ◽  
Surface Area ◽  
Lamellar Structures ◽  
Area Increase ◽  
Surface Area Increase ◽  
Surface Increase

The texture changes of carbonaceous substances caused by high pressure (1 500 Mpa) have been studied by sorption of N2 (at 78 K) and CO2 (at 298 K) and by electron microscopy. The surface increase of cokes is observed in the region of micropores as well as meso- and macropores, whereas that of semicoke is only limited to the region of meso- and macropores. No effect is observed with formed coke and charcoal. Microscopically it has been found that cokes form a layer texture, whereas semicokes show a disconnection of microbreccia character. The surface area increase is ascribed to formation of new surfaces produced by shift and/or deformation of lamellar structures.

Surface-Area Increase in Tissue Expansion

1988 ◽  
Vol 82 (5) ◽  
pp. 838-839 ◽  
Author(s):  
Julien H. A. van Rappard ◽  
J. Molenaar ◽  
K. van Doom ◽  
G. J. Sonneveld ◽  
J. M. H. M. Borghouts ◽  
...  
Keyword(s):  
Surface Area ◽  
Tissue Expansion ◽  
Area Increase ◽  
Surface Area Increase

Enhanced oxygen evolution catalysis by aluminium-doped cobalt phosphide through in situ surface area increase

2020 ◽  
Vol 10 (8) ◽  
pp. 2398-2406 ◽  
Author(s):  
Timothy E. Rosser ◽  
Juliana P. S. Sousa ◽  
Yasmine Ziouani ◽  
Oleksandr Bondarchuk ◽  
Dmitri Y. Petrovykh ◽  
...  
Keyword(s):  
Surface Area ◽  
Oxygen Evolution ◽  
Oxidation Behaviour ◽  
Al Doping ◽  
Cobalt Phosphide ◽  
Area Increase ◽  
Surface Area Increase

Al-doping of cobalt phosphide oxygen evolution catalysts results in enhanced performance which, based on in situ and operando analysis, is shown to result from a surface area increase associated with modified oxidation behaviour.

INTERPRETATION OF THE BASAL METABOLIC RATE OF CHILDREN OF UNUSUAL BODY BUILD

PEDIATRICS ◽  
1951 ◽  
Vol 8 (5) ◽  
pp. 616-627
Author(s):  
ALBERTA ILIFF ◽  
VIRGINIA A. LEE ◽  
ROBERT C. LEWIS
Keyword(s):  
Surface Area ◽  
Research Council ◽  
Basal Metabolism ◽  
Healthy Children ◽  
Clinical Use ◽  
Small Children ◽  
Body Build ◽  
Child Research ◽  
Area Increase ◽  
Surface Area Increase

The relative predictive value of six methods of reference frequently used to determine the BMR of children of unusual body build has been studied. The methods of reference based on the Child Research Council standards which were employed for this purpose were those for cal./hr./sq. m., cal./hr./kg. and cal./hr./cm., each referred to age, and cal./hr. referred to surface area, weight and height, respectively. An analysis was made of 558 determinations of basal metabolism obtained on 86 healthy children of the Child Research Council, of 946 basal metabolism tests on 793 children described in the literature and of 80 basal metabolism tests on 74 children observed by Gordon. The study included children between 2 and 16 years of age whose weight or height or both weight and height fell above the 90th percentile or below the 10th percentile of all the children of similar age on whom the Council standards had been established. The results of this analysis show that the methods of reference of cal./hr. referred to surface area and of cal./hr. referred to weight are reliable for the interpretation of BMR determinations on children of all six types of body build. This is also true of cal./hr./sq. m. referred to age except in the case of very small children or dwarfs for whom high BMR are found. These observations might well have been anticipated since height and weight and surface area increase with age in children, but weight and surface area give a better evaluation of body mass than does height. The methods of reference of cal./hr./kg. referred to age, cal./hr./cm. referred to age and cal/hr. referred to height are not so reliable, either individually or collectively, for routine clinical use as are the other three methods of reference. Nevertheless, the deviations in the BMR obtained by these less satisfactory methods of reference may be of considerable importance in understanding the problems of a child of unusual body build. The use of the proper methods of reference based on reliable standards will result in trustworthy BMR for children of unusual body build.

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