scholarly journals MECHANICAL STRENGTH OF COAL: METHODS OF DETERMINATION AND FACTORS OF INFLUENCE (REVIEW)

2021 ◽  
Vol 6 ◽  
pp. 4-17
Author(s):  
V.V Koval ◽  
D.V. Miroshnichenko ◽  
O.V. Bogoyavlenska
Keyword(s):  
Mechanical Strength ◽  
Physical Properties ◽  
Physical And Mechanical Properties ◽  
Mechanical Tests ◽  
Point Of View ◽  
Statistical Characteristics ◽  
Measuring Instruments ◽  
Industrial Processing ◽  
Average Value ◽  
Advantages And Disadvantages

The article substantiates the importance and problems of determining of such an indicator of the quality of solid fossil fuels, as mechanical strength. The strength of coal depends on a large number of factors (viscosity, brittleness, properties of structural bonds, etc.), the change of which is impossible to take into account. Therefore, the strength of coal in the sample, piece, pack and formation must be represented by some integral index, which inevitably fluctuates around a certain average value and can be determined only approximately. The evaluation of the strength properties of coal should be carried out on the basis of mass tests using statistical methods that allow to calculate the average value and coefficient of variation. Since the strength dispersion is mainly due to the natural inhomogeneity of the coal, the excessive accuracy of the measuring instruments has almost no effect on the statistical characteristics. Laboratory methods of mechanical tests of mine samples, in comparison with full-scale, as a rule, are very accessible and, at qualitative performance of tests, are highly reliable. The properties of coal as an object of enrichment and use are largely related to its physical properties. The physical properties of coal and mineral impurities significantly affect the formation of the main parameters that characterize the particle size distribution and fractional composition, it`s changes during the mining, transportation and enrichment processes. The basic physical and mechanical properties of solid fuels from the point of view of their industrial processing have been listed, the review has been made of the most widespread methods of study of coals mechanical durability and the equipment used for these purposes. The main advantages and disadvantages have been summarized of these methods, as well as their relationship. The factors have been Indicated tinfluencing the mechanical strength of coal. The expediency of using existing methods from the point of view of informativeness for thesphere of its application has been estimated. The methods common in the coal processing industry are considered in more detail. Keywords: coal, solid fuel mining, mechanical strength, determination methods, influencing factors, grinding strength, crushing index. Corresponding author V.V. Koval, e-mail: [email protected]

scholarly journals Behaviour of Autoclaved Aerated Concrete Blocks using Alkali-Resistant Glass Fibre as Additive

2020 ◽  
Vol 8 (6) ◽  
pp. 3508-3513
Keyword(s):  
Compressive Strength ◽  
Physical Properties ◽  
Glass Fibre ◽  
Physical And Mechanical Properties ◽  
Slight Variation ◽  
Average Value ◽  
Autoclaved Aerated Concrete ◽  
Concrete Blocks ◽  
Aerated Concrete ◽  
Masonry Units

Autoclaved aerated concrete (AAC) blocks are the lightweight and green concrete blocks that are composed of cement, fly ash, lime, gypsum and aluminium powder. Depending on its density AAC consists of up to 80% of air by volume. Due to their low density and lightweight Autoclaved aerated concrete blocks exhibit so many favourable physical properties that these have got attention from all around the globe. Due to these enhanced properties Autoclaved aerated concrete blocks are extensively used as masonry units in all types of construction. On one hand AAC blocks have no comparison with other types of masonry units in terms of physical properties but on other hand AAC blocks are found to have low compressive strength relatively. In this study an attempt has been made to study the influence of Alkali-Resistant Glass Fibre additive on the physical and mechanical properties of Autoclaved aerated concrete blocks. Four sets of samples were cast and named as A, B, C and D with the fibre additive contents as 0%, 0.1%, 0.2% and 0.3% respectively (by dry weight of all the ingredients).Each sample set consisted of three specimens and the average value of the three samples were taken. For example, the average value of the three specimens- A1 , A2 , and A3 was taken as A and so on. Fibre additive influenced the aeration process of Autoclaved aerated concrete by increasing the rising/aeration time by 8%. The investigated fibre additive increases the compressive strength by 0%, 10%, 24% and 13.8% respectively to the added fibre contents of 0%, 0.1%, 0.2%, and 0.3% respectively. The optimal content of Alkali-Resistant Glass Fibre additive to be added for obtaining the highest compressive strength is 0.2%. Further investigations have shown a slight variation in density (about 0.2%) between the normal and modified Autoclaved aerated concrete blocks.

scholarly journals PHYSICAL-MECHANICAL CHARACTERIZATION OF THE WOOD OF Plathymenia reticulata BENTH (VINEYARD-OF-FIELD) NATIVE SPECIES OF THE CERRADO OF THE STATE OF TOCANTINS

FLORESTA ◽  
2020 ◽  
Vol 51 (1) ◽  
pp. 247
Author(s):  
Raquel Marchesan ◽  
Lucas Alves Ferreira Souza ◽  
Rodrigo Araújo Fortes ◽  
Raydel Lorenzo Reinaldo ◽  
André Orathes do Rego Barros ◽  
...  
Keyword(s):  
Native Species ◽  
Mechanical Characterization ◽  
Basic Density ◽  
Physical And Mechanical Properties ◽  
Mechanical Tests ◽  
The State ◽  
Native Forest ◽  
Average Value ◽  
Heavy Construction

Physical-Mechanical Characterization of the Wood of Plathymenia reticulata Benth (Vinhático-do-campo) Species of the Cerrado Biome of the State of Tocantins. The objective of this work was to determine the physical and mechanical properties of Plathymenia reticulata Benth (vinhático-do-campo) wood to indicate its potential use. The wood used in the production of the specimens came from the municipality of Dueré – TO native forest. The basic density, wood retractability, and anisotropy coefficient were obtained from physical tests, and the values of axial compression and static flexion resistance from the mechanical tests. The values obtained showed that the Plathymenia reticulata Benth wood fits the C40 resistance classification for hardwoods, determined by the Brazilian Standard (NBR7190). The average value of the basic density found was 0.64 g cm-3, classified as a medium density wood and the values of tangential, radial and volumetric retractability were 6.11%, 3.06%, 9.39 %, respectively. As for its mechanical characteristics, it presented average values of compressive strength parallel to the fibers, resistance to static flexion, and elastic modulus equal to 58.8MPa, 128.2 MPa, and 12760.0MPa, respectively. The vinhático-do-campo wood can be classified as stable wood and its physical characteristics suggest a normal quality. The species can be applied in light and heavy construction.

PROSPECTS FOR THE USE OF SURFACE WAVE LINES IN LOCAL DATA NETWORKS

2020 ◽  
Author(s):  
Н.В. ЛЕМЕШКО ◽  
С.С. ЗАХАРОВА
Keyword(s):  
Surface Wave ◽  
Spatial Separation ◽  
Point Of View ◽  
Data Networks ◽  
Measuring Instruments ◽  
Electromagnetic Environment ◽  
Local Data ◽  
Transmission Networks ◽  
Advantages And Disadvantages ◽  
Physical Principles

Оценивается перспектива использования линий поверхностной волны в локальных сетях передачи данных. Кратко рассмотрена физика работы такихлиний, показаны их достоинства и недостатки с точки зрения указанного применения. На основе известного способа возбуждения поверхностной волны предложен подход к контролю ее наличия с применением типовых средств измерений, предусматривающий формирование отраженной поверхностной волны и использование циркулятора. Представлена информация о конструкции рупорного перехода с боковым питанием и подстройкой, обеспечивающими узкополосное согласование, необходимое при работе линий поверхностной волны в условиях сложной электромагнитной обстановки либо их массового применения при ограниченном пространственном разносе. The article assesses the prospect of using surface wave lines in local data transmission networks. The physical principles of operation of such lines are briefly considered, their advantages and disadvantages from the point of view of the indicated application are shown. Based on the known method of surface wave excitation, an approach is proposed to control its presence using standard measuring instruments, which involves the formation of a reflected surface wave and the use of a circulator. Information is presented on the design of a horn junction with lateral power supply and adjustment, providing nar-row-band matching required for the operation of surface wave lines in a difficult electromagnetic environment or their widespread use with a limited spatial separation.

scholarly journals The effect of the lenght of storage on the amount of lycopene in the fruits of tomato (Lycopersicon esculentum L.)

2008 ◽  
Vol 56 (2) ◽  
pp. 245-250
Author(s):  
Anton Uher
Keyword(s):  
Lycopersicon Esculentum ◽  
Nutritional Value ◽  
Point Of View ◽  
Human Organism ◽  
Tomato Fruits ◽  
Processing Industry ◽  
Industrial Processing ◽  
Average Value ◽  
Nutritional Qualities ◽  
Lycopene Content

We focused on tomatoes for industrial processing due to its economical importance for its lycopene content. The objective of our research is to find the variation of lycopene content in tomato fruits depending upon the length of after harvest storage and thermic treatment, which is inevitable when being industrialy processed. From the point of view of nutritional qualities the most relevant contentual substance of tomatos are carotenoids, included lycopene.At average for tree following experimental years we learnt significant differences regarding the content of lycopene and the length of storage of tomato fruits. Immediately after the harvest and proccesing tomato fruits contained, at average for tree years, 103.24 mg of lycopene. After 14 days the content of lycopene declined to 46.76 mg . kg−1 of fresh mass. After 30 days the average value dropped to 29.26 mg . kg−1. This fact comfirms that boiling respectively thermic treatment increases the content of lycopene in tomato fruits, particulary in our experiment to the value 83.33 mg . kg−1. At varieties Ladislav, Peto 86, Prémium, Salus the content of lycopene has even risen in comparison with its content up to 48 hours after the harvest. Tomato (Lycopersicon esculentum L.) belongs to the most signifficant vegetable varieties either for its exploitation in processing industry as well as for its nutritional value with extraordinary beneficial effect for human organism.Although the content of lycopene is genetically stable attribute, its content in our experiment ranged from 45.39 mg . kg−1 (Prémium variety) to 77.98 mg . kg−1 (Zámčan variety), which are significant differences.

scholarly journals DETERMINATION OF THE CAUSES OF DESTRUCTION OF HIGH-STRENGTH FASTENING ELEMENTS

2021 ◽  
Vol 83 (2) ◽  
pp. 207-219
Author(s):  
O.B. Berdnik ◽  
I.N. Tsareva ◽  
L.A. Krivina ◽  
S.V. Kirikov ◽  
Yu.P. Tarasenko ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Phase Composition ◽  
Physical And Mechanical Properties ◽  
High Strength ◽  
Mechanical Tests ◽  
Modern Technology ◽  
Regulatory Requirements ◽  
Two Phase ◽  
Average Value ◽  
Elastic And Plastic Deformations

Intensively operated modern technology requires the use of high-strength fasteners. The article presents the results of studies of the structure and physical and mechanical properties of the material of fastening elements (threaded hardware) in order to determine the causes of their destruction during operation. The fractographic analysis of fractures of fractured bolts revealed pronounced centers of crack initiation with traces of delayed brittle fracture, which is typical for high-strength hardware that are under high load for a long time, close to the yield point. Mechanical tests of the studied fastening elements showed increased values of ultimate strength. The performed relaxation tests of the material of broken bolts also revealed an increased value of the microplasticity limit, which is responsible for the onset of plastic deformation processes in microvolumes of the material, and for the material of whole hardware, the value of the limit is included in the permissible interval. At the same time, the average hardness of the material of all products meets the regulatory requirements. The maximum spread of hardness 70 HB is fixed on the destroyed bolt. Using the experimental values of microhardness, theoretical estimates of the coefficient of plasticity, which characterize the ability of a material to perceive elastic and plastic deformations, were carried out. To ensure a sufficient level of ductility of a long-term working metal material, the ductility coefficient must be at least 0.8. The average value of the hardness of the material of the fastening elements satisfies this criterion for assessing ductility. According to the results of a step-by-step analysis of the microstructure of the samples, the inhomogeneity of the distribution of the carbide phase over the cross-section of the bolts was established. The two-phase composition (a-Fe + Fe3C) of steel was established by X-ray structural analysis, which confirms the results of microstructural studies. It should be noted that the phase composition of all studied samples is identical. Based on the results of the studies carried out, it was found that the destruction occurred due to the reduced strength and increased fragility of the material due to the presence of microdefects. The material of the whole bolts in terms of structure and mechanical properties comply with regulatory requirements.

scholarly journals SIFAT FISIKA DAN MEKANIKA PAPAN SEMEN DARI SERAT KULIT BATANG SAGU (Metroxylon Sp)

2019 ◽  
Vol 7 (3) ◽  
Author(s):  
Peterson Peterson ◽  
M Dirhamsyah ◽  
Nurhaida Nurhaida
Keyword(s):  
Mechanical Properties ◽  
Physical Properties ◽  
Water Absorption ◽  
Fiber Length ◽  
Physical Property ◽  
Physical And Mechanical Properties ◽  
Modulus Of Rupture ◽  
Average Value ◽  
Wood Processing ◽  
Cement Board

The research aims to examine the physical and mechanical properties of cement board from sago fiber waste (Metroxylon Sp) based on cement size and composition and determine the best ratio of cement and sago fiber (Metroxylon sp) and meet the standards of JIS A 5417: 1992. The study was conducted at the Laboratorium WoodWorkshop, Wood Processing, Wood Technology and PT. Duta Pertiwi Nusantara Pontianak. The method used was an experimental method in a factorial Randomized Complete Design factorial experiment of 2 x 3 with 3 replications and a total of 18 experiments. The factors used in sago fiber length (Factor A) and fiber (Factor B).  The tests include physical properties and mechanical properties with a target density of 1 gr / cm³. The results showed that the average value of the physical properties of the cement board included density 0.9713 gr / cm³ - 1.2246 gr / cm³, moisture content 3.5054% - 3.9448%, water absorption 0.9746 % - 1.1318% and thick Development 0.8649% - 0.9892%. The mean mechanical properties of cement board include MOE 10,564,6646 kg / cm² - 35,475,7865 kg / cm² and MOR 7,5797 kg / cm² - 25,8554 kg / cm². The best research is in treatment (a1b2) with a ratio of cement and fiber (80:20) with a length of sago fiber 2 cm and meets the standards of JIS A 5417: 1992 with the of 23, with a physical property density value of 1.2198 gr / cm³, water content is 3.7401%, water absorption is 0.9944%, and thickness development is 0.9048%. The mechanical properties value of Modulus of Elasticity is 28439.1825 kg / cm² and Modulus of Rupture is 25.8554 kg / cm².Keyword:   Cement Comparison,  Fiber Length, Sago Fiber, Physical and Mechanical Propertie

Physical and mechanical properties of hemp seed

2012 ◽  
Vol 26 (2) ◽  
pp. 211-215 ◽  
Author(s):  
A. Taheri-Garavand ◽  
A. Nassiri ◽  
S. Gharibzahedi
Keyword(s):  
Mechanical Properties ◽  
Moisture Content ◽  
Physical Properties ◽  
Loading Rate ◽  
Physical And Mechanical Properties ◽  
Interaction Effects ◽  
Mechanical Tests ◽  
Rupture Force ◽  
Hemp Seed ◽  
Effect Of Moisture

Physical and mechanical properties of hemp seedThe current study was conducted to investigate the effect of moisture content on the post-harvest physical and mechanical properties of hemp seed in the range of 5.39 to 27.12% d.b. Results showed that the effect of moisture content on the most physical properties of the grain was significant (P<0.05). The results of mechanical tests demonstrated that the effect of loading rate on the mechanical properties of hemp seed was not significant. However, the moisture content effect on rupture force and energy was significant (P<0.01). The lowest value of rupture force was obtained at the highest loading rate (3mm min-1)and in the moisture content of 27.12% d.b. Moreover, the interaction effects of loading rate and moisture content on the rupture force and energy of hemp seed were significant (P<0.05).

scholarly journals DETERMINATION OF ACCEPTABLE SAMPLE WEIGHT OF MINERAL FERTILIZERS TO KEEP THOSE SAMPLES TO BE REPRESENTATIVE ONES IN TERMS OF PARTICLE SIZE DISTRIBUTION

2019 ◽  
Vol 62 (6) ◽  
pp. 106-111
Author(s):  
Dmitriy V. Yunovidov ◽  
Maksim N. Nadezhin ◽  
Konstantin V. Aksenchik ◽  
Elizaveta E. Sidorova ◽  
Irina V. Nadezhina
Keyword(s):  
Particle Size ◽  
Particle Size Distribution ◽  
Physical Properties ◽  
Size Distribution ◽  
Chemical Properties ◽  
Statistical Characteristics ◽  
Mineral Fertilizers ◽  
Sieve Analysis ◽  
Average Value ◽  
Level Of Significance

The article discusses the relationship between the mass of the laboratory sample and the homogeneity of its particle size distribution. The aim of the work is to estimate the limits of the sample mass reduction, at which it remains representative in particle size distribution. A relation was pointed out between the chemical and physical properties and the particle size distribution of fertilizers. The use of this parameter as one of the basic physical properties of industrially produced mineral fertilizers was justified. At the same time, using a smaller sample will reduce the time for analysis in industrial laboratories. An experiment was proposed and implemented to assess the representativeness of sample of fertilizers with different masses. Samples of several brands of industrially produced granulated mineral fertilizers were studied. A sieve analysis of samples was carried out in accordance with accepted standards (for < 1 mm, 1-2 mm, 2-3.15 mm, 3.15-4 mm, 4-5 mm, 5-6.3 mm, > 6.3 mm fractions). A comparison between the obtained results and industry-specific technique for determining the particle size distribution on the woven sieve was given. According to the obtained data, the main statistical characteristics of the analysis were calculated: mathematical expectation (average value), standard deviation and confidence interval. The homogeneity of the average values and variances of the obtained samples for the 50 and 150 g of fertilizers was investigated using Student's and Fisher's tests for a 0.05% level of significance. To confirm the test results, a graphic distribution of sample with different mass and the fraction < 2 mm was built. Conclusion about the allowable mass of a representative sample of granular mineral fertilizers for analyzing the particle size distribution and the associated with physical and chemical properties of fertilizers was made.

PEMANFAATAN KAYU AKASIA MANGIUM (Acacia mangium Willd) UNTUK MEBEL

2012 ◽  
Vol 4 (1) ◽  
pp. 1
Author(s):  
Djoko Purwanto
Keyword(s):  
Mechanical Properties ◽  
Compressive Strength ◽  
Physical Properties ◽  
Treatment Process ◽  
Acacia Mangium ◽  
Physical And Mechanical Properties ◽  
Wood Fibers ◽  
Test Parameters ◽  
Mechanical And Physical Properties ◽  
Scale Scores

Timber Acacia mangium (Acacia mangium, Willd) for Furniture. The study aims to determine the mechanical and physical properties and the decorative value (color and fiber) wood of acacia mangium with using finishing materials. This type of finishing material used is ultran lasur natural dof ,ultran lasur classic teak, aqua politur clear dof, aqua politur akasia dan aqua politur cherry. After finishing the wood is stored for 3 months. Test parameters were observed, namely, physical and mechanical properties of wood, adhesion of finishing materials, color and appearance of the fiber, and timber dimensions expansion. The results showed that the mechanical physical properties of acacia wood qualified SNI. 01-0608-89 about the physical and mechanical properties of wood for furniture, air dry the moisture content from 13.78 to 14.89%, flexural strength from 509.25 to 680.50 kg/cm2, and compressive strength parallel to fiber 342.1 - 412.9 kg/cm2. Finishing the treatment process using five types of finishing materials can increase the decorative value (color and fiber) wood. Before finishing the process of acacia mangium wood has the appearance of colors and fibers and less attractive (scale scores 2-3), after finishing acacia wood fibers have the appearance of colors and interesting and very interesting (scale 4-5).Keywords: mangium wood, mechanical properties, decorative value, finishing, furniture.

BRUSH ALLOY 3

Alloy Digest ◽  
1983 ◽  
Vol 32 (3) ◽  
Keyword(s):  
Mechanical Properties ◽  
Thermal Conductivity ◽  
Corrosion Resistance ◽  
Physical Properties ◽  
Copper Alloy ◽  
Elevated Temperatures ◽  
Physical And Mechanical Properties ◽  
Heat Treating ◽  
Good Resistance ◽  
Good Corrosion Resistance

Abstract BRUSH Alloy 3 offers the highest electrical and thermal conductivity of any beryllium-copper alloy. It possesses an excellent combination of moderate strength, good corrosion resistance and good resistance to moderately elevated temperatures. Because of its unique physical and mechanical properties, Brush Alloy 3 finds widespread use in welding applications (RWMA Class 3), current-carrying springs, switch and instrument parts and similar components. This datasheet provides information on composition, physical properties, hardness, elasticity, and tensile properties as well as fatigue. It also includes information on corrosion resistance as well as casting, forming, heat treating, machining, joining, and surface treatment. Filing Code: Cu-454. Producer or source: Brush Wellman Inc..

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