Application of Visualization Technology in Professional Teaching LI Baofu, SONG Jiayong School of Energy Science and Engineering Henan Polytechnic University, P. R. China, 454000 libf@hpu.edu.cn Abstract: Mining engineering is a complicated and large systematic engineering. For example, students do not have clear understanding in space position of production systems for underground mining in coal mine. And students who do not have the intuition comprehend little in the process of disturbance and distortion induced by mining-related strata in coal seam. Lectures with viable combination of professional teaching and visualization technology with computer make the teaching lively and vivid. Besides, the integration enhances teaching quality more effectively. Therefore, it achieves the purpose for teaching and studying in the meantime. Key words: Visualization, Mining engineering, teaching, Computer aided design, CAD, Numerical simulation 1 Introduction Mining engineering is a complicated and large systematic engineering. So it is necessary that optimum design and scientific management with computer in mining engineering be executed. Presently, with rapid development in multimedia technology in computer, applications with computer in coal mine are more and more sensible. The depth and extent are larger and larger. The development of multimedia technology with computer provides a basis and guarantee for the transformation that from bald teaching process to visual teaching process in mining engineering teaching. Mining geology is complex in underground mining. Because space positions of entry system are interlaced, it is hard for undergraduates who have got little any practical experiences in mining engineering to understand. In order for students of mining engineering to understand entry systems well in underground mining, teachers can plot and design three-dimensional mine models with computer-aided visualization technology. With theoretic method, it is hard to directly calculate the stress status for coal faces or entries as well as the process of destroying and deformation in surrounding rock in underground mining. Neither are they able to be reappeared by means of physics experiment. But via computer numerical simulation, stress distribution can be described in these mechanics models, and process of strata behaviors can also be reappeared. In this way, visualization is achieved. Therefore, applications of visualization technique with computer ought to be reinforced in teaching special series of lectures in mining engineering. 2 Applications of Visualization Technique with CAD 2.1 Problems existed in teaching special series of lectures Underground coal mines are typical of working underground, many production systems and complex working procedure. Underground production systems consist of developing, hoisting, ventilation, drainage, power supply etc. <Mining Science> is an important course learned by undergraduates of mining engineering in our university. Students will meet with many problems when they study this course. And the main problem they are faced with is that they cannot comprehend exactly and completely entry space positions of production system in underground mining. At present, teaching materials and reference materials have hardly been found for students to study the course as reference in terms of models of entry in coal mine 547
which is three-dimensional. So students have no option but to understand on their own with teacher s explanation, and go to laboratory to pay a visit to the physical model. But these two methods cannot solve the problems and the students yet cannot comprehend the three-dimensional models correctly. < Mining Science > course is of great importance in many aspects, such as the students who study this lecture well will pass the course design and graduate design easily, and they can do well in their work. So, what can we do to make this course become an easy and applicable course? How can we make students comprehend space positions of entries easily for main production systems in underground mine? These two questions are worth the teachers thinking and improving. 2.2 Brief Introduction of Visualization Technology with CAD Visualization in scientific computing(visc) was brought forward in 1980s, and developed fast. It is a hot spot of new technology in computer application in 1980s. In 1990s, mining software developed fast. And its typical software is three-dimensional mineral model. Software referring to the above covers in many aspects, such as geological materials processing, mineral deposit modeling, serving design in mining etc [1]. Currently, CAD technology runs towards three-dimensional entity, visualization, and integration. However, CAD technology in mining develops relatively slow and still has much to go in terms of application in mining engineering [2]. AutoCAD is software of computer aided design which is developed by Autodesk Company in America, the most popular software in for engineering in China. Modeling technology of AutoCAD can be used for plotting three-dimensional system model of entry lay-out for underground mine. Thus, visualization is achieved, since it is effectively tackled and solved in the process of teaching < Mining Science >. 2.3 Establishing Teaching Model with Visualization Technology of CAD <Computer Drawing > is a lecture course designated for mining engineering by Henan Polytechnic University, and this main objective of lecture is to design drawings with Auto CAD software. Because this course is taken after < Mining Science > has been studied, training of professional knowledge should be intensified in the process of teaching the course. In this way, students can design more special drawings for their practice exercise. Students should be encouraged to design coal mine three-dimensional system model via the modeling technology of AutoCAD, and they are able to plot the various and hard-to-imagine three-dimensional system models covered in < Mining Science >. Taking this method, two evident teaching effects have been achieved: firstly, professional knowledge and the course can be combined, thus better triggering students enthusiasm; Secondly, students are able to understand the professional knowledge deeply; thirdly, the concept of three-dimensional mine system can established by students; Last but not the least, students are guided to plot different three dimension scale models of mine, and teachers gather up these models for the following teaching lectures. Thus, visualization of teaching models is achieved in the teaching process. Fig.1 and Fig.2 are three-dimensional models plotted with three-dimensional modeling technology. Both are preferable models in teaching < Mining Science >. With these three-dimensional models, visualization teaching has been achieved. 548
Figure 1 Room and pillar mining Figure 2 Three-dimensional model of pit bottom 3 Visualization Teaching Methods with Numerical Simulation 3.1 Visualization Meaning in Lecture Course < Rock Pressure and Strata Control > narrates dynamic three-dimensional space problems. So teacher can hardly explain the lecture clearly in class, thus students cannot establish the concept of three-dimensional dynamic space. The objective and aim for teaching and cultivation are not well achieved in this case. Even if students got to coal mines for intern practice, they can only see the static local phenomena, such as destruction or invalidation of support in entry, distinct distortion of entry, roof fall in mining face, sloughing of ribs etc. However, they cannot yet gain that direct cognition for rock pressure and the process of destruction or invalidation for underground rock [3]. Stress around entry and mining face is not be seen directly, since they are only considered with theoretical formulae derivation and image of teaching material. This method hinders students from understanding the theory of mining pressure and from teachers delivering students capacity for practical problems. Moreover, lecture session are limited, so complicated formulae are not completely interpolated in class. However, it is hard to gain the stress of one point around surrounding rock by observing mining process in mine. According to the above problems, numerical calculation method has been adopted preferably. The development of numerical calculation was highly regarded by mining field. It has been introduced into mining to calculate rock pressure in mine, thus increasingly playing an important role in rock pressure and strata control in coal mine [4]. 3.2 Brief Introduction of Numerical Simulation Software Strata movement overlying coal face is a very complex and dynamic process. In order to understand the mechanics and range of overlying strata movement, damage processing on roof strata deforming should be studied. At present, RFPA2D is numerical calculation software, which can simulate the whole process on rock crack initiating, expanding until fracturing for simulated rock. Based on the theory of continuum medium mechanics and damage medium mechanics, the software has two functions on stress and failure analyses [5]. So, with RFPA2D, the processing on rock mass rupture and strata movement under mining action can be simulated [6, 7, 8]. 3.3 Example of Visualization Teaching (1) Process Simulation in Distortion of Roof Stratum under Stress in Process of Coal Mining Model computation was executed along with mining in coal face. Top of model was free boundary, gravity stress was brought to be bear according to mining depth; Left and right boundary are continuous borders for binding horizontal displacement; Lower boundary of model is clamp. They are shown in Figure 3. Different advancing distance of coal face according to the transformation of vertical stress in roof of coal seam is calculated. 549
Figure 3 Mechanic model of numerical calculation (2) Transaction of Visualization in Analog Result They are gained through transaction of visualization in analog result that process of bed separation, falling and stress status in roof stratum with mining. This result can be used for explaining example in class teaching to achieve visualization teaching and supply useful data for theory in teaching materials. a. Vertical stress distribution of main roof first weighting 6.00E+01 5.00E+01 4.00E+01 M P a ) ( 3.00E+01 位单 2.00E+01 1.00E+01 0.00E+00 0 50 100 150 200 250 300 350 单位 (m) b. Vertical stress distribution curve of main roof first weighting 3.50E+01 3.00E+01 2.50E+01 2.00E+01 ( M P a ) 位 1.50E+01 单 1.00E+01 5.00E+00 0.00E+00 0 50 100 150 200 250 300 350 单位 (m) c. Vertical stress distribution of main roof periodic d. Vertical stress distribution curve of main roof weighting periodic weighting Figure 4 Relationship of vertical stress distribution with mining space 4 Tag At present, with new employment situations and cultivating models of qualified personnel, how to advance teaching quality lectures in mining engineering, how to advance students extent and depth of cognition of professional knowledge? These questions have been hot points of teaching investigation and innovation for teachers. With combination of computer visualization technology and special series of lectures, teaching quality are advanced. At the same time, they have advanced students computer skills and capacity of solving practical problems with special software. Successful application of computer visualization and innovation is important for advancing teaching quality and cultivating qualified personnel. 550
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