In order to achieve directional dispersing of metal particles, a detonation-driven model placing metal particles and explosives together inside a rigid pipe was developed in this study. The one-dimensional detonation wave theoretical analysis was conducted to explore the relationship between the dispersing velocity and the mass of particles and explosives. Moreover, the three-dimensionl finite element simulations were performed with mass ratio of explosive/ particle at 0.5:1, 1:1 and 2:1 respectively, while the particle diameter was 0.05cm. An empirical formula describing the relationship between the dispersing velocity and the mass ratio of explosive particle was obtained as the result of theoretical analysis. The simulation results demonstrated that the particles fly along the axissteadily, with little scattering and good directionality. The dispersing velocities derived from theoretical analysis were found to agree with the results of the numerical simulations, which suggested the availability of this investigation.
Keywords: Detonation-driven, particle, directional dispersing, theoretical analysis, numerical simulation
In order to improve the preparation level of acid aluminium super-hydrophobic film coating, in this paper, a simple and rapid method for the preparation of super-hydrophobic films was proposed. Aluminium substrate was used as the substrate, and the surface roughness structures were first etched with dilute hydrochloric acid, and then configure the n-dodecyl alcohol, fourteen acid ethanol soaking solution, the treated substrate is immersed in the soaking solution by a tapering machine, and finally, a superfine hydrophobic film having a special surface is obtained by heat treatment. The experimental results show that the surface morphology of the film is observed by scanning electron microscopy, and then measured its hydrophobic angle up to 160.9 degrees.
Keywords: Superhydrophobic, hydrochloric acid etching, fourteen aluminum acid
India’s emergence as a major economic hub has ensured steady growth across the nation’s mining industry. As a result of strong economic growth, the Indian mining industry increased at a compound annual growth rate (CAGR) of 25.8% during the 2008-13 period to a value of more than US$20bn in 2009. With relatively stable growth rates, resilient economic structure and future growth opportunities, India has always been an attractive destination for expansion of activities such as construction, infrastructure and power generation. These activities will always continue to drive the demand for investing on mineral industries. It is well known that a typical economic pie for a mining process indicates that drill and blast accounts for 20% while rest of the operations are seriously affected by it. Rock fragmentation by blasting is of critical economic importance to the mining industries worldwide. A blast can be designed to attempt the elimination of oversized particles or to minimize the amount of fine particles in the muckpile. To optimize the entire system, it is more prudent to attempt a blast design that provides optimum platform for rest of the operations. The authors discuss a case study of limestone and an aggregate stone quarry wherein the studies have been conducted on the blast performance in terms of degree of fragmentation using digital image processing technique.
Keywords: Blast design, fragmentation, geology, Fragalyst, productivity and ground vibration
With the development of metallurgical technology, a lot of large spanmetal beam structures appear in mining, machinery and construction. Structural damage identification is extremely important in engineering. The technology of structural damage identification based on dynamic characteristics has been one of the hot issues in current engineering research. Based on the absolute curvature difference modal analysis method and perturbation theory, the finite element model of a simply supported beam structure was established by ANSYS software, so as to study the damage localization and damage quantification. Under the condition of single damage and multiple damage of simple beam structure, reducing the elastic modulus of each element in the model by means of numerical simulation, and analyzing the change of curvature mode to enable study the damage localization. Then, based on the perturbation theory, the curvature difference mode method is used to analyze the damage quantitatively. The results are of great reference value for damage detection of large spanbeam structures.
Keywords: Metallurgical, damage identification, metal beam structure, absolute curvature difference, perturbation
Cutting temperature always highly reaches over to 1000oC during high speed machining with Al2O3 ceramic tools. Diffusion wear is the main wear mechanisms at such high temperature. In this paper, the rules of diffusion wear for Al2O3 ceramic tools are studied based on thermodynamics. Dissolution concentrations in typical normal workpiece materials of ceramic tool material at different temperature are then calculated. Diffusion reaction rules in high temperature are also analyzed using Gibbs free energy criterion, it was found that the theoretical results were uniform with the experimental data; and the diffusion solubility of Al2O3 ceramic tools is usually much smaller. The order of dissolution of Al2O3 ceramic tools in machining several typical normal workpieces is as follows: titanium> nickel> steel, At the same cutting condition, when machining cast iron and 35# steel, the wear performance of tools is very different and the wear mechanism should be researched more. The results will provide useful references for tool material design and selection.
Keywords: Thermodynamics characteristics, Al2O3 ceramic tool, tool wear
The distribution of low rank coal in many geographies accounts for almost 50% of the coal deposits of the world. Presence of high moisture and high propensity for spontaneous combustion limits its use in industries. An attempt towards reducing the moisture and enhancing calorific value would make the low rank coal more usable for different industries. For this study Indonesian coal has been considered as there are large resources of lignite/low rank coal specifically in Sumatra. Low rank coal (LRC) is also known as lignite or brown coal which has moisture content up to 45%. Their applications are limited due to spontaneous heating property, high volatile matter (VM). LRC is difficult to handle and involves high transportation cost also. If coal is only dried, it turns brittle and breaks down into dust while handling. After extensive research on Indonesian coal at laboratory and pilot scale, briquetting technology appears to overcome these inherent difficulties of LRC and is ready for experimental production. With briquette technology, coal is dried into tailor made briquettes of adequate strength. There are various advantages of coal briquettes like lower moisture content, higher heating value, improved plant efficiency, enhance safety, low transportation cost, reduce fire hazard, reduce space requirement and reduce green house gas emissions etc. Briquette technology can help standardizing Hardgrove Grindability Index (HGI) of coal and can be maintained at a value as suitable to the end user. This paper deals with briquetting technology which can produce 2000 TPD of desired quality briquetted coal out of low rank coal on a commercial scale.
Keywords: Low rank coal, Briquette technology, volatile matter, Hardgrove grindability index
The mechanical properties of concrete bridge located in mining area are influenced by the mining area environment and thickness of pavement. The unreasonable design of pavement layer will easily lead to the concrete bridge deck cracking. Based on FEM (finite element method), Jiaozuo Bridge is taken as an example to study on mechanical influence of pavement on concrete bridge deck with different thicknesses. A three-dimensional finite element model is built to simulate the bridges with three kinds of thickness of concrete deck pavement respectively. The results show that the maximum longitudinal and lateral tensile stresses in girder increase with the thickness of deck pavement which will cause the girder cracking while the maximum lateral tensile stress in concrete deck pavement decreases. When the thickness of waterproofing layer of deck pavement is 11cm, the stresses in deck pavement are all the least ones among the three cases respectively. The possibility of being crack in deck pavement is the lowest. And the design scheme which the thickness of waterproof concrete pavement is 11cm will be the best.
Keywords: Concrete bridge, mining area, pavement thickness, finite element method
This paper mainly aimed at the risk factors such as rock cracking in the process of mining operations, the use of a visual warning function of inspection robot instead of manual inspection operations. The inspection robot body module and the three joint robot arm and the telescopic boom structure can be moved on the steel cord which is laid along the mine overhead line, and the dynamic model of the inspection robot is determined. The robot vision system to detect mine tunnel crack images collected through the camera inspection robot for visual processing using the improved Otsu algorithm for gray-scale image binarization can improve the effect of image processing.
Keywords: Robot; dynamics model; image binarization; improved Otsu algorithm
Abstract: Available soon.
Keywords: Available soon.
Highway traffic is the lifeline of the national economy, and the bridge is the throat of the road, so the well used status of bridge is an important determinant factor of highway traffic safety. With the development of metallurgical and welding technology, high performance steels have been widely used in large span concrete bridge structures. Based on the theory of finite element method and ANSYS software, Lianhuo highway prestressed concrete continuous beam bridge is taken as the research object, and a threedimensional finite element model of the bridge is established to analyse the stress characteristics, load effect, internal force of the structure in the ultimate limit state of bearing capacity and serviceability under different conditions. The results can provide a reliable basis for the design of the bridge.
Keywords: High performance, T-beam bridge, ultimate limit state, serviceability limit state, modal analysis