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Specific Energy of Hard Coal Under Load

Abstract

The article presents results of experimental tests of energy parameters of hard coals under loading, collected from research sites located within five main geologic structures of Upper Silesian Coal Basin (GZW) - Main Trough, Main Anticline, Bytom Trough, Rybnik Trough and Chwałowice Trough. Coals from12 mines were analysed, starting with seams of group 200, through groups 400, 500, 600 and, finally, seams of group 700. Coal of each of the groups of seams underwent uniaxial compression stress of the energy parameters, in a servo-controlled testing machine MTS-810NEW, for the full range of strain of the tested coal samples. Based on the tests the dependence of different types of specific energy of longitudinal strain of coals on the value of uniaxial compression strength was determined. The dependence of the value of dissipated energy and kinetic energy of coals on the uniaxial compression strength was described with a linear function, both for coals which due to their age belong to various bed sand for various lithotypes of coal. An increase in the value of dissipated energy and in kinetic energy was observed, which was correlated with an increase in uniaxial compression strength of coal. The share of dissipated energy is dominant in the total energy of strain. Share of recoverable energy in the total energy of strain is small, independent of the compression strength of coals and is at most a few per cent high. In coals of low strength and dominant share of dissipated energy, share of recoverable energy is the biggest among the tested coals. It was shown that following an increase in compression strength the share of recoverable energy decreases, while the share of dissipated energy in the total energy increases. Further studies of specific energy of longitudinal strain of rocks in the full-range strain will be the next step inperfecting methodology of research into natural rock burst susceptibility of Carboniferous rock mass and changes in the susceptibility resulting from mining activity.

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Calculation of critical flow depth using method of algebraic inequality

Abstract

To calculate the critical depth and the least specific energy of steady non-uniform flows in open channels, one has to solve the polynomial equations. Sometimes, the polynomial equations are too difficult to get them solved. In this study, the theory of algebraic inequality has been used to derive formulas for determining the critical depth and the least specific energy of a steady non-uniform flow in open channel. The proposed method has been assessed using examples. Results using this new method have been compared to those using other conventional methods by engineers and scientists. It is found that the proposed method based on algebraic inequality theory not only makes the calculation process to be easy, but also gives the best calculation results of the critical depth and the least specific energy of a steady nonuniform flow.

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The Production Efficiency and Specific Energy Consumption During Processing of Corn Extrudates with Fresh Vegetables Addition

Abstract

The aim of the work was to determine the influence of screw speed and variable amounts of fresh vegetable additives on selected aspects of extrusion-cooking of corn-vegetable blends. Corn grit as a basic component was supplemented with a fresh pulp of beetroot, carrot, leek and onion in amounts of 2.5-10% in the recipe. The extrusion-cooking was carried out using a single-screw extruder in the temperature range 120-145°C and extrudates were formed into directly expanded snacks. Two indicators were measured: the production efficiency (Q) and the specific mechanical energy (SME) consumption. As a result of the findings it was noted that the rotational speed of the extruder’s screw showed a greater impact on both production efficiency and SME as compared to the variable amounts of applied additives. A tendency to increased efficiency and specific mechanical energy consumption was observed along with the increase of screw speed during processing. The highest production efficiency was observed if fresh leek and onion were used as additives and the highest extrusion speed screw was applied. The largest specific energy consumption was noted during the extrusion-cooking of blends containing fresh carrot and onion addition at high screw speed.

Open access
An Investigation Concerning the Effect of Canal width Contraction that May be Needed in the Location of Constructing Some Irrigation Works

Abstract

The compatibility between the needed structural designed dimensions of the irrigation works and the dimensions of the water stream or the canal in which the irrigation work will be located has a great importance from more than one point of view. As it is well known, the main aim of the designer of such works is to reach the optimum design for maximum performance efficiency with economical cost, and minimize negative technical impacts that may be harmful to the safety of the whole work. Since the complete suitability between the obtained designed dimensions of the different construction elements of the work, and the original properties and dimensions of the canal in which the work will be constructed, is rarely occurring. The designer always has to make some changes in the original engineering properties and dimensions of canals, such as bed width, bed level, and/or inside side slope, to reach the needed suitable compatibility between the structural design and the natural original canal cross section. For the economical purposes, the design always needs less width of the work, than the width of the bed of the original stream cross section, so a contraction may be needed where the work will be constructed; the literature indicated that, such a contraction must not be less than 0.6 of the original bed width. That contraction, of course, has a direct impact on the different hydraulic parameters, such as water depth, velocity, and flow regime in the location of the work. Changes of such hydraulic parameters may exceed their safe permissible values, and so the whole structure may face some dangerous situations, which must be overcome. In this paper, we present a technical survey of the previous research concerning canal width contraction, with the needed technical comments, and comparisons as a logical approach for a master-thesis under the same title.

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Effect of canal width contraction on the hydraulic parameters and scour downstream water structures

Abstract

The dimensions of many water streams, which satisfy proper hydraulic conditions, may not be compatible with the designed dimensions of an irrigation work that needs to be constructed in some locations. The design requirements of such irrigation works may involve a contraction in the channel width in the required location. This contraction, of course, affects different flow properties and the scour hole formed downstream of these structures. Therefore, the present experimental study aims to investigate the effect of the transition angle and the contraction on the flow properties and on the scour phenomenon downstream water structures. Through 460 experimental runs, carried out on 20 experimental models, the study proved that, for an efficient hydraulic performance and economic design, the best transition angle (θ) for the approaches of water structures is 30° with a relative contracted width ratio (r = b/B) not less than 0.6.

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Modeling Some Drying Characteristics of Cantaloupe Slices

and Food Science, 19, 127-135. Behbahani M., 2005 - Genetic diversity among Iranian melons ( Cucumis melo L.) via SSR markers. MS Thesis, Boualisina University, Hamedan, Iran. Chayjan R. A., Parian J. A., Esna-Ashari M., 2011a - Modeling of moisture diffusivity, activation energy and specific energy consumption of high moisture corn in a fixed and fluidized bed convective dryer. Spanish Journal of Agricultural Research, 9(1), 28-40. Chayjan R. A., Peyman M. H., Esna- Ashari M., Salari K

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Electrooxidation of phenol on carbon fibre-based anodes through continuous electrolysis of synthetic wastewater

phenol using graphite anodes. Sep. Sci. Technol . 34(4), 699–708. 15. Mu’azu, N.D., Al-Yahya, M., Al-Haj-Ali, A.M. & Abdel- Magid, I.M. (2016). Specific energy consumption reduction during pulsed electrochemical oxidation of phenol using graphite electrodes. J. Environ. Chem. Eng . 4, 2477–2486. DOI: 10.1016/j.jece.2016.04.026. 16. Hussain, S.N., Roberts, E.P.L., Asghar, H.M.A., Campen, A.K. & Brown, N.W. (2013). Oxidation of phenol and the adsorption of breakdown products using a graphite adsorbent with electrochemical regeneration. Electrochim. Acta

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On the Cutting Performance of Coated HSS Taps When Machining of Austenitic Steel

Abstract

The paper deals with a quality of the PVD coated HSS taps when cutting the stainless austenitic chromiumnickel non-stabilized steel DIN 1.4301 (X5CrNi 18-10). The main attention is focused on the analysis of loading (cutting moment, specific energy) of the HSS taps by means of pieso-electrical dynamometer Kistler 9272 and the relation between the quality of duplex and triplex PVD coatings and their effects on the quality of machined thread surfaces and tool life of the taps. The results showed a safe and stabilized cutting with acceptable quality of threads for HSSE with the TiN+TiCN+DLC coating.

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Coke and coal as reductants in manganese ore smelting: An experiment

Abstract

The effect of coke and bituminous coal on the reduction of medium-grade manganese ore in ferromanganese production was investigated. Charges of 30 kg medium grade manganese ore, 12 kg limestone and varied amounts of coke and coal were smelted in a Submerged Electric Arc Furnace (SAF) at temperatures of 1300°C to 1500°C. The composition of the ferromanganese and the slag were determined by X-Ray Fluorescence. It was found that using coke as a single reductant resulted in a 96% yield of ferromanganese which was higher than by using coal either as a single reductant or in a mixture of coal and coke. It was also found that using coke as a single reductant resulted in the lowest specific energy consumption. Using coal as reductant produced ferromanganese containing high sulfur and phosphorus.

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Handling and Curing Characteristics of Cut-Strip Tobacco. Part 1: Effect of Strip-Size, Packing Density and Mode of Orientation

Abstract

Previous work has demonstrated potential handling and curing efficiencies in the use of cut-strip tobacco. The present work considers further the effect of cut-strip size, packing density and mode of orientation on cured leaf chemistry (starch, reducing sugars, and total alkaloids) and leaf quality. Results showed that cured leaf chemistry of 15.2 × 22.9 cm cut-strip more closely matched properties of whole leaf than pieces 15.2 × 15.2 cm or smaller. Starch contents were significantly higher for the smaller cut-strip sizes, perhaps due to edge drying effects, while alkaloids were significantly lower. Within the range of 194 to 292 kg/m, packing density had little effect on leaf chemistry, with the exception that reducing sugars were slightly lower for the higher packing densities. This could be due to a longer time for the drying front to move through the more tightly packed tobacco, and hence more respiratory loss of sugars. Government grades and average market prices of cured strips were essentially unaffected over the range of strip sizes or packing densities tested. Based on airflow resistance measurements and observed drying characteristics, vertical orientation of strips was far superior to horizontal orientation, both with vertical airflow through the tobacco. The higher packing density reduced specific energy use (kWh/kg green tobacco) by as much as 22%, indicating potential energy savings for cut-strip over whole leaf curing.

Open access