The analysis of relaxed criteria for erosion-control filters

1994 ◽  
Vol 31 (6) ◽  
pp. 829-840 ◽  
Author(s):  
H. Den Adel ◽  
M.A. Koenders ◽  
K.J. Bakker
Keyword(s):  
Mathematical Model ◽  
Grain Size ◽  
Granular Material ◽  
Key Words ◽  
Experimental Work ◽  
Transport Model ◽  
Base Material ◽  
Erosion Control ◽  
Sand Surface ◽  
Moving Base

To optimize the design of erosion-control filters a transport model is presented for moving base material in horizontally loaded filters that are not geometrically stable. Supporting experimental work is used to obtain the parameters in a descriptive quantitative mathematical model. A set of three fixed parameters describes most experiments. Exceptions are where the filter to base grain-size ratio is so small that geometrical obstruction takes place and where this ratio is so large that the turbulences in the flow cause the sand surface under the filter to ripple. The latter case is described with a slightly amended parameter to allow for the amount of fluctuation in the problem. Key words : filtration, transport, experiments, theory, granular material, barriers.

Internal stability of granular filters

1985 ◽  
Vol 22 (2) ◽  
pp. 215-225 ◽  
Author(s):  
T. C. Kenney ◽  
D. Lau
Keyword(s):  
Particle Size ◽  
Grain Size ◽  
Particle Size Distribution ◽  
Granular Material ◽  
Key Words ◽  
Distribution Curve ◽  
Internal Stability ◽  
Small Particles ◽  
Particle Size Distribution Curve ◽  
Internal Instability

Internal stability of a granular material results from its ability to prevent loss of its own small particles due to disturbing forces such as seepage and vibration. Internal instability results from the inability of a soil to act as a filter to prevent loss of its own small particles.Within pores in the load-bearing fabric of a cohesionless, granular material there can exist loose particles, and whether or not these particles can be removed by seepage depends on (i) particle size distribution curve of the whole material, (ii) density of the compacted material, and (iii) severity of the disturbing forces.Results of seepage tests are presented for a variety of compacted, cohesionless materials, some of which experienced loss of small particles (unstable gradings) and others of which experienced no such loss (stable gradings). From a synthesis of these results a method is proposed for evaluating the potential for grading instability based on the shape of a material's grain size curve. However, the surest method of making such an evaluation is to perform seepage tests following the procedure described in the paper. Key words: internal stability, grading stability, suffosion, tests, filters.

Результаты опытно-экспериментальной работы по формированию коммуникативной компетентности преподавателей в процессе повышения квалификации

2019 ◽  
pp. 66-69
Author(s):  
Гульжан Назарматова
Keyword(s):  
Key Words ◽  
Research Methods ◽  
Experimental Work ◽  
Communicative Competence ◽  
Communication Competence ◽  
Diagnostic Tools ◽  
Advanced Training ◽  
Teacher Communication

Аннотация: В статье рассматриваются результаты опытно-экспериментальной работы по формированию коммуникативной компетентности преподавателей педагогических направлений в процессе повышения квалификации. Представлены основные этапы, направления, база и методы исследования опытной работы. Описывается диагностический инструментарий по определению уровня сформированности коммуникативной компетентности преподавателей. Проводится анализ данных констатирующего и формирующего экспериментов по формированию коммуникативной компетентности преподавателей в процессе повышения квалификации. Ключевые слова: преподаватель, коммуникативная компетентность, повышение квалификации, опытно - экспериментальная работа. Аннотация: Макалада квалификациясын жогорулатуу процессиндеги педагогикалык багытындагы мугалимдердин байланыш компетенттүүлүгүн калыптандыруу боюнча тажрыйба ишинин жыйынтыктары жөнүндө айтылат. Эксперименталдык иштин изилдөө ыкмалары, базасы, негизги этаптары, жана багыттары берилет. Мугалимдердин байланыш компетенттүүлүгүн калып- тандыруу көлөмүн аныктоо үчүн диагностикалык каражаттар айтылат. Квалификациясын жогорулатуу процессиндеги мугалимдердин байланыш компетенттүүлүгүн калыптандыруу боюнча аныктоо жана калыптандыруучу эксперименттериндеги алынган маалыматтардын анализи келтирилет. Түйүндүү сөздөр: окутуучу, байланыш компетенттүүлүк, квалификациясын жогорулатуу, эксперименталдык тажрыйба иш. Abstract: The article discusses the results of experimental work on the formation of communicative competence of teachers of pedagogical areas in the process of advanced training. The main stages, directions, base and research methods of experimental work are presented. The diagnostic tools for determining the level of formation of communicative competence of teachers are described. The data of ascertaining and formative experiments on the formation of communicative competence of teachers in the process of advanced training are analyzed. Key words: teacher, communication competence, qualification advancement, skilled - experimental work.

scholarly journals Performance evaluation of recycled granular material as sustainable sub-base material

2020 ◽  
Author(s):  
Venkatesh Noolu ◽  
B. Murali Krishna ◽  
Yeswanth Paluri ◽  
Sudhakar Mogili
Keyword(s):  
Performance Evaluation ◽  
Granular Material ◽  
Base Material

Culvert inlet efficiency

1995 ◽  
Vol 22 (3) ◽  
pp. 611-616 ◽  
Author(s):  
C. D. Smith ◽  
A. G. Oak
Keyword(s):  
Key Words ◽  
Experimental Work ◽  
Control Efficiency ◽  
Head Losses ◽  
Coefficient Of Discharge ◽  
The University

The results of experimental work carried out on culvert inlet efficiency at the University of Saskatchewan are reported in this paper. Efficiency is reported in terms of coefficient of discharge when the culvert operates with inlet control, and in terms of the coefficient of entrance loss when the culvert operates with outlet control. A larger coefficient of discharge or a smaller coefficient of entrance loss represents a higher efficiency. Seven different culvert inlets were tested for both inlet and outlet control, and for the headwater level both above and below the elevation of the crown of the pipe at the inlet. The results are reported in nondimensional charts. Key words: culvert flow, inlet control, outlet control, efficiency, head losses, capacity.

scholarly journals Reduction of technogenic load from sludge collectors due to separation and dehydration of the stored material

2019 ◽  
Vol 109 ◽  
pp. 00010
Author(s):  
Olena Bubnova ◽  
Oleksandr Shevchenko
Keyword(s):  
Mathematical Model ◽  
Grain Size ◽  
Economic Efficiency ◽  
Mining Industry ◽  
Initial Distribution ◽  
Power Industry ◽  
Material Layer ◽  
Use Of Technology ◽  
Mineral Stock ◽  
Mining Industry Wastes

Purpose: the identification of geomechanical problems of mining industry wastes accumulation and substantiation of the ways for their solution with the possibility of processing the watery technogenic feedstock. It has been shown that in order to reduce the technogenic load, it is necessary to reduce the area of land under the waste ponds and the accumulated volumes themselves of mining and enrichment wastes. It has been revealed that the mineral stock, formed from wide grain-size classes with a high content of particles less than 0.2 mm, is dewatered up to 18 – 22 % by traditional methods and is practically not classified. A mathematical model has been proposed of screening and dewatering kinetics, which takes into account comprehensively the initial distribution of particles and liquid throughout the height of the screened material layer, segregation, mixing, sifting, vibrational transportation features and change in the height of the layer. The use of technology will allow: increase the economic efficiency of enterprises; to expand the feedstock base for construction, coke and chemical industries and power industry; to solve the problems of creating additional containers for storing the wastes; to improve significantly the environmental situation in the mining and processing regions.

The Effect of Curing Time on the Properties of Fly Ash-Based Geopolymer Bricks

2012 ◽  
Vol 626 ◽  
pp. 937-941 ◽  
Author(s):  
W.I. Wan Mastura ◽  
H. Kamarudin ◽  
I. Khairul Nizar ◽  
Mohd Mustafa Al Bakri Abdullah ◽  
H. Mohammed
Keyword(s):  
Compressive Strength ◽  
Fly Ash ◽  
Water Absorption ◽  
Sodium Hydroxide ◽  
Sodium Silicate ◽  
Experimental Work ◽  
Base Material ◽  
Curing Time ◽  
Curing Conditions ◽  
Alkaline Activator

This paper reports the results of an experimental work conducted to investigate the effect of curing conditions on the properties of fly ash-based geopolymer bricks prepared by using fly ash as base material and combination of sodium hydroxide and sodium silicate as alkaline activator. The experiments were conducted by varying the curing time in the range of 1-24 hours respectively. The specimens cured for a period of 24 hours have presented the highest compressive strength for all ratio of fly ash to sand. For increasing curing time improve compressive strength and decreasing water absorption.

Noise Reduction Using Finite-Length Flexible Segments

1999 ◽  
Vol 122 (2) ◽  
pp. 94-108 ◽  
Author(s):  
Brian Chapnik ◽  
I. G. Currie
Keyword(s):  
Mathematical Model ◽  
Finite Length ◽  
Experimental Work ◽  
Acoustic Noise ◽  
Characteristic Impedance ◽  
Fluid Loading ◽  
Piping Systems ◽  
And Performance ◽  
Insertion Losses ◽  
Acoustical Energy

In this work, the reduction of acoustic noise in piping systems through the installation of finite flexible segments is explored. A mathematical model describing the relevant parameters is developed. To verify the model, experimental work is undertaken using rubber hoses as flexible segments and air as the contained fluid. The effect of the segment on propagating acoustical energy is studied in terms of its insertion loss. Both theoretical and experimental results indicate that, for light fluid loading, the flexibility of the segment is only important when significant axial shell resonances exist, or when one or both acoustical termination impedances at the ends of the segment are much larger or smaller than the characteristic impedance of the medium. Further, the model indicates that for heavier fluid loading (i.e., when the compressibility of the flexible section is significant in relation to the bulk compliance of the fluid), in addition to higher associated insertion losses, the finite length resonances become more pronounced, and performance is less sensitive to small variations in the termination impedances. [S0739-3717(00)00402-5]

scholarly journals Evaluation of Cryogenic Mechanical Properties of Resistance Seam-Welded Invar Alloy Sheet by Instrumented Indentation Test

2020 ◽  
Vol 8 (12) ◽  
pp. 1009
Author(s):  
Seunghun Choi ◽  
Jongho Won ◽  
Jung-Jun Lee ◽  
Hee-Keun Lee ◽  
Seong-Min Kim ◽  
...  
Keyword(s):  
Grain Size ◽  
Plastic Zone ◽  
Base Material ◽  
Indentation Test ◽  
Welding Current ◽  
Optical Microscope ◽  
Alloy Sheet ◽  
Invar Alloy ◽  
Instrumented Indentation ◽  
Average Grain Size

Invar alloy sheet was welded by resistance seam welding (RSW) with a constant electrode force and three different welding currents. Tensile properties were evaluated using instrumented indentation testing (IIT) with a spherical indenter and microstructure observations were obtained under an optical microscope. IIT performed on the base material at room temperature (RT) and −163 °C, a cryogenic temperature (CT), gave results in good agreement with those of tensile testing. The strength of each zone was higher in the order of heat-affected zone (HAZ) < weld nugget (WN) < base material (BM) because the amount of cold working was least in the BM, heavy metal elements and carbon vaporized during melting, and the WN was formed more tightly than the HAZ, effectively constraining the plastic zone generated by the indentation. As for the welding current, the nugget, which becomes larger and tighter as the current increases, more effectively constrained the plastic zone in the indentation, and this soon increased the strength. Generally, Invar is known to consist of single-phase austenite, and microstructure observations have confirmed that the average grain size is ordered as BM < HAZ < WN. Fan-like columnar grains developed in the direction of the temperature gradient, and equiaxed grains were observed near the BM. It was confirmed that the grain size in the WN also increases as the current is increased. Interestingly, the constraint effect with increasing nugget size was more important for strength than the grain size.

scholarly journals Microstructural Evolution and Mechanical Properties of Friction Stir Welded Butt Joints of 5A06 Alloy Ultra-Thin Sheets

Materials ◽  
2019 ◽  
Vol 12 (23) ◽  
pp. 3906 ◽  
Author(s):  
Yang Han ◽  
Xiaoqing Jiang ◽  
Tao Yuan ◽  
Shujun Chen ◽  
Dongxiao Li ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Grain Size ◽  
Grain Boundaries ◽  
Microstructural Evolution ◽  
Welding Speed ◽  
Base Material ◽  
Thin Plates ◽  
Al Alloy ◽  
Minimum Thickness ◽  
Friction Stir

Ultra-thin plates have great potential for applications in aircraft skin, the packaging industry, and packaging of electronic products. Herein, 1 mm-thick 5A06 Al alloy was welded with friction stir welding. The microstructural evolution of the welds was investigated in detail with optical microscopy, scanning electron microscopy, and electron backscatter diffraction. The results showed that the friction stir welds of 1 mm-thick 5A06 Al alloy were well formed without obvious defect and with a minimum thickness reduction of 0.025 mm. Further, the grain size and the proportion of low-angle grain boundaries decreased with decreasing welding speed, because of the increasing degree of dynamic recrystallization. Among all of the welded joints, the welding speed of 100 mm/min yielded the smallest grain size and the highest proportion of high-angle grain boundaries, and thus the best mechanical properties. Specifically, the tensile strength of the joint was greater than that of the base material, while the elongation reached 80.83% of the base material.

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