Analytic hierarchy process-based evaluation research on coal supply chain management collaborative system

Jun 2018 / by Bo Wen

In the dynamic market environment of economic globalization, the supply chain management (SCM) in Chinese coal industry is faced with serious problems such as lowered overall efficiency and yield rate, while the “horizontal integration” management to strength the supply chain management has obtained obvious advantages in the competition. Based on AHP, this paper analyses the network structure and collaborative network operation of 9 coal supply chains (SC), build the index system of coal supply chain management collaborative system (SCMCS), and makes dynamics simulation study for coal SCMCS by adopting the Vensim software. The results show that the index system of coal SCMCS is composed of three collaborative indexes in terms of strategy, business process and customer service, where the business process index is the core of index system. Also, the dynamics simulation modelling has been made for the system, to obtain the general level of CS, rebuild the sub-system flow chart and then promote the degree of order for the sub-systems in the adjusted plan.
Keywords: Analytic hierarchy process (AHP), supply chain management (SCM), collaborative system (CS), dynamics simulation modelling

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Specific surface area of construction minerals

Jun 2018 / by Peng Tian, Lei Nie and Gaofeng Zhan

Pore characteristics are the key index to characterize the surface characteristics of mineral materials. The surface pore characteristics of road of construction minerals are the key indexes to influence the adhesion and pavement performance of asphalt mixture. Adsorption and desorption experiments on limestone, andesite and basalt. Using nitrogen as adsorbent in the experiment. Through the calculation, the specific surface area and pore size distribution of multiple groups of mineral materials were obtained. The results show that the pore characteristics of the mineral surface are closely related to the composition and genesis. The average pore size and specific surface area of limestone are much higher than basalt and andesite. The average pore diameter of limestone is 5.6 times than that of basalt and 8 times than that of andesite. The BET specific surface area is 4.5 times than that of basalt and 7.8 times than that of andesite. Limestone is a sedimentary rock, the surface is rougher than that of basalt and andesite. There is a great difference in the texture of limestone from different quarries. The average pore size of basalt and andesite is similar, and the surface pore characteristics of them even produced by different quarries are close.
Keywords: Specific surface area, pore, composition, adsorption, characteristic model

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Deformation layer characteristics of ultrasonic deep rolling processing (UDRP), laser shot peening (LSP) and shot peening (SP) for Inconel718 super-alloy

Jun 2018 / by Liqiong Zhong, Yilong Liang and Hao Hu

This paper, by applying the ultrasonic deep rolling processing (UDRP), laser shot peening (LSP) and shot peening (SP) for Inconel718 super-alloy, adopts the laser confocal scanning microscope (LCSM) to observe surface topography and measure surface roughness, EBSD to observe the microscopic feature of surface hardened deformation layer, and x-ray stress analyzer and ultra-micro dynamic microhardness tester to measure residual stress and distribution of microhardness. The results show that, with the adopted surface hardening process parameters, the surface roughness presents in the order UDRPUDRP and the layer depth of residual compressive stress UDRP>SP>LSP; surface microhardness LSP>SP>UDRP, and hardening depth SP ≈ UDRP>LSP.
Keywords: Inconel718 super-alloy, ultrasonic deep rolling processing (UDRP), laser shot peening (LSP), shot peening (SP)

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Study on coal mine safety evaluation based on factor analysis

Jun 2018 / by Ya Wang and Tingting Wang

The safe production of coal mine is an important part of national safety production, which is related to the healthy and stable development of coal industry. It is very important to find a comprehensive and reasonable coal mine safety evaluation method for coal mine safety production. In this paper, a comprehensive evaluation index system of coal mine safety is systematically established, and a comprehensive evaluation model of coal mine safety based on factor analysis principle is proposed. Then, with three Shanxi coal mine enterprises as examples for case study, we use principal component analysis and SPSS software to analyse the main factors influencing coal mine safety and their mutual relations on the basis of the details of each factor. By calculating the scores of principal components and the comprehensive safety score, we undertake a comprehensive analysis and evaluation on coal mine safety.
Keywords: Coal mine safety; factor analysis; index system; evaluation method

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Prediction of coal bump with respect to local mine stiffness and post-failure stiffness using numerical modelling

Jun 2018 / by Raja S., Prabhat Kumar Mandal, P. S. Paul and Arka Jyoti Das

In India, coal deposits under the shallow depth of cover amenable by opencast and underground mining are fast exhausting and the focus is being shifted towards the deepseated coal deposits. But, due to the complex geo-mining conditions, techno-economic indices and non-availability of suitable technological solutions, the mining industry is facing tremendous difficulties to exploit the deep-seated coal deposits. Deep-seated coal deposits require immediate attention for its successful exploitation. Underground exploitation of the deep-seated deposits faces a number of geotechnical problems like coal bumps, pillar squeezes, sudden collapse, floor heaving etc. Coal bump is the most difficult, hazardous, long-standing engineering problem associated with the underground coal mining nearly from past three centuries. Coal bump induces the catastrophic failure of mine structures resulting in loss of life and damage to the machinery. If anyone could identify the burstproneness before the commencement of the mining operation, a suitable method of mining can be suggested for efficient extraction of coal and can avoid the major strata control problems. In this paper, a brief review of causes, occurrence and prediction of coal bumps has been described. A case study mine has also been considered for prediction of coal bump using numerical modelling.

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Techno-economic analysis for development of a drive in view of geo-mining conditions – a case study

Jun 2018 / by K. K. Rao, B. S. Choudhary, Ajay Ghade and A. Amjath Ali

This paper presents all the rock mechanics studies carried out at an underground metal mine in Kadapa, Andhra Pradesh. The rock mechanics investigations in this mine include optimization of pillar dimensions by numerical modelling, the feasibility of hangwall lode mining at shallow depth, support design for deeper levels, instrumentation to monitor the strata for an experimental hangwall stope. The main aim is to improve extraction ratio and the mine safety levels from these rock mechanics studies to develop a mine. The effect on the linear advance in both footwall lode and hangwall lode is studied, monitored and found that there is almost 25% increase in total cost per round of blast due to difficult geo-mining conditions and affecting total cost per tonne of ore extracted from hangwall in contrast to footwall lode development and safety aspects. A critical case study with techno-economic cost analysis in view of their geo-mining conditions has been discussed.
Keywords: Metal mine; rock mechanics; development; supports; linear progress; blasting

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Assessment of auto-oxidation potential of some Indian coals by differential thermal analysis (DTA) technique

Jun 2018 / by B. Behera and H. B. Sahu

It is a well-known fact that coal when exposed to air, undergoes oxidation, even at ambient temperature conditions.The process is exothermic in nature. If the amount of heat liberated during the process is not dissipated, it leads to an increase in temperature, which in turn enhances the rate of reaction, ultimately culminating in open fire. These fires are the major causes of accidents resulting in loss of lives and property across the globe. Apart from loss of valuable coal reserves, blockage of resources and capital, reduction of heating values and coking properties; it also causes serious environmental pollution. However, all coals are not susceptible to auto-oxidation to the same extent. Therefore, accurate assessment of the oxidative tendency is essential to plan the production and storage capabilities in mines.There are different innovations and technologies available in various parts of world to assess and control spontaneous heating tendency, till date there is no unanimity to adopt single method for its assessment. In this study, an attempt has been made to study the auto-oxidative tendency of Indian coal seams by using different thermal technique (DTA). For this purpose 48 coal samples were collected from all major coalfields of the country.The intrinsic properties of these samples were determined using proximate analysis and bomb calorimeter. Correlation study between the intrinsic parameters and susceptibility indices indicate that DTA can be a better method for assessment of the auto-oxidation potential of coal.
Keywords: Auto-oxidation, spontaneous heating, differential thermal analysis, intrinsic properties, coal

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Effect on microstructure of TMT welded bar under different cooling media

Jun 2018 / by R. P. Singh, Md. Anis Raza, Mousumi Mallick and M. K. Verma

Arc welding is widely used for domestic as well as industrial purposes as it is very convenient to use. Mechanical properties such as tensile strength and hardness depend on microstructure. This paper presents the results of metallography examination of weld zone and heat affected zone (HAZ) in the welded rod which are welded and cooled in air, transformer oil, kerosene oil and water. The rate of cooling differs from each media thus there is microstructure change in weld zone as well as HAZ. In the weld zone, hardness is found to be more in case of transformer oil cooled sample in comparison with others cooling method applied here. The toughness of water cooled sample is found to, be more because of its presence of large amount of ferrite region along with pearlite and martensite. In the heat affected zone, water cooled sample is found to possess mare hardness due to formation of martensite. The arc welded transformer oil cooled sample seems to be best among all with regard to its structure, hardness and toughness.
Keywords: TMT, microstructure, welding, quenching, heat affected zone

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