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Pre-splitting is a controlled blasting technique with applications in open pit mines. The main objectives of pre-splitting in open pit mining are: preventing/controlling back-break; controlling excessive ground vibrations; and filtering the effects of explosive gases from production blasting. This technique is especially effective in back-break control through providing a separating surface between the main blasting pattern and open pit final walls. In this study, a large open pit mine was the case study for the goal of designing pre-splitting through implementation of direct and cost effective experiments. Three tests were designed and performed at the mine. Back-break was successfully controlled through proper design of pre-splitting based on the results of the experiments.

Fracture toughness and brittleness are of the most crucial rock features for underground excavation and drilling in rock mass. Developed standard tests to determine rock fracture toughness are very difficult as well as time consuming; furthermore, they require high-level accuracy during sample preparation and testing. An attempt has been made to propose simple relations to determine fracture toughness modes I and II based on brittleness indexes B 1 , B 2 and B 3 in this paper. The data for regression were gathered from the literature, including modes I and II fracture toughness, uniaxial compressive strength and tensile strength. It was obtained that both fracture toughness modes I and II of different rock types give reasonable correlations with brittleness index B 1 . No correlation was observed between fracture toughness modes and other brittleness indexes.

Multiple correspondence analysis and cluster analysis (MCACA) is developed in this paper, and then used to extract the main advantages of multiple correspondence analysis and hierarchical cluster analysis, and to unify the R- and Q-mode cluster analysis for a large data set. A systematic program to recognise the regional geochemical patterns is built up based on this method. With this program, the complex tasks for data interpretation could be achieved by simple processes, and important geochemical information could be displayed by a single diagram, i.e. the dendrogram. As a case study, the regional geochemical pattern recognition for the Ravar 1 : 100 000 sheet in the Kernam Province is discussed. The results show that many hidden geochemical patterns related to the lithologies, structures and prospecting targets are revealed by the geochemical map, and that the main geochemical patterns are related to certain geological patterns. By finding contrasts between geochemical patterns and geological patterns, the MCACA results assist the geological mapping in this area. Stream sediment geochemical data obtained in regional geochemical exploration in Iran provide useful information regarding geology and other factors, and the method described in this paper provides a new way to examine this type of resource.

Ground vibrations are unavoidable in each rock blasting projects. The prediction of ground vibration components has a great importance in the minimisation of the environmental complaints. Estimating the particle velocity and other components of ground vibration with reliable approaches will be very useful in blast design. Peak particle velocity is the most important criterion for analysing dangers resulting from ground vibration. Up to now, researchers have proposed many different formulae to calculate this parameter, but none of them are applicable for all areas and based upon regional conditions such as geological, technical, geotechnical, rock mechanical and so on. Karoun 3 Project is located in southwest of Iran. The aim of this study is to predict peak particle velocity in this project. For this purpose, vibrations from the Karoun 3 excavations were measured and the recorded data were statistically analysed and two empirical relationships with good correlation were established.

Abstract: In this paper, a chattering-free sliding mode controller design for uncertain chaotic systems is presented. Since the implementation of the sliding mode control may cause a significant problem of chattering, many modified methodologies have been developed to overcome this drawback. However, each of them has own problems such as lack of robustness against disturbance variations, steady-state error, large convergence time and effect on transient performance. This paper proposes an improved sliding mode control strategy in which a modified sliding condition in a continuous function in control signal is taken into account instead of discontinuous part and also it adds an auxiliary continuous control to the control input. Then, the stability of controlled system is proved by using Lyapunov’s direct method. The usefulness of this proposed method for eliminating the chattering phenomenon in transient and steady states, in the face of uncertain chaotic systems with disturbances, is well appeared. For this purpose, the Lorenz system is studied and its simulation results are presented to demonstrate the effectiveness of the proposed control scheme. [Copyright &y& Elsevier]

Abstract: In this paper, an adaptive control method for set-point tracking of the Lorenz chaotic system by using non-linear feedback is proposed. The design procedure of the proposed controller is accomplished in two steps. At the first step, using Lyapunov’s direct method, a non-linear state feedback is selected so that without any need to apply identification techniques, in despite of the uncertain parameters existence in the system state equations, the asymptotic stability of the general Lorenz system is guaranteed in a stochastic point of the manifold containing general system equilibrium points. At the second step, a linear state feedback with adaptive gain is added to the prior controller to eliminate the tracking error. In order to guarantee the system asymptotic stability at desired set-point, the indirect Lyapunov’s method is used. Finally, to show the effectiveness of the proposed methodology, the simulation results of different experiments including system parameters changes and set-point variation are provided. [Copyright &y& Elsevier]

One of the most critical and complicated steps in mining design is a suitable mining method selection, based on geological, geotechnical, geographical and economical parameters. There are many factors involved in mining method selection, which influence the decision making process. In this paper, technique for order preference by similarity to ideal solution (TOPSIS), with 13 criteria, is used to develop a suitable mining method for the Golbini No. 8 deposit in Jajarm, Iran. Six alternatives mining methods, i.e. conventional cut and fill, mechanised cut and fill, shrinkage stoping, sublevel stoping, bench mining and stull stoping, are evaluated. The studies show that the suitable mining method for this deposit with regard to the present situation is conventional cut and fill method.

In this paper, a method for estimating an attractor embedding dimension based on polynomial models and its application in investigating the dimension of Bremen climatic dynamics are presented. The attractor embedding dimension provides the primary knowledge for analyzing the invariant characteristics of the attractor and determines the number of necessary variables to model the dynamics. Therefore, the optimality of this dimension has an important role in computational efforts, analysis of the Lyapunov exponents, and efficiency of modeling and prediction. The smoothness property of the reconstructed map implies that, there is no self-intersection in the reconstructed attractor. The method of this paper relies on testing this property by locally fitting a general polynomial autoregressive model to the given data and evaluating the normalized one step ahead prediction error. The corresponding algorithms are developed in uni/multivariate form and some probable advantages of using information from other time series are discussed. The effectiveness of the proposed method is shown by simulation results of its application to some well-known chaotic benchmark systems. Finally, the proposed methodology is applied to two major dynamic components of the climate data of the Bremen city to estimate the related minimum attractor embedding dimension. [Copyright &y& Elsevier]

The problem of Lyapunov Exponents (LEs) estimation from chaotic data based on Jacobian approach by polynomial models is considered. The optimum embedding dimension of reconstructed attractor is interpreted as suitable order of model. Therefore, based on global polynomial mode ling of system, a novel criterion for selecting the embedding dimension is presented. By considering this dimension as the model order, the best nonlinearity degree of polynomial is estimated. The selected structure is used for local estimating of Jacobians to calculate the LEs. This suitable structure of polynomial model leads to better results and avoids of sporious LEs. Simulation results show the effectiveness of proposed methodology.

One of the most difficult problems in mining operation is how to determine optimum cutoff grades of ores at different periods over the lifespan of the mine that will maximize the net present value (NPV) of the mine. Maximizing the NPV of a mining operation, subject to different constraints is a non-linear programming problem. These problems can often be solved by the use of gradient methods, direct search methods or intelligent optimization methods. In this paper, a hybrid genetic algorithm combined with the grid search method is used to find the optimum cutoff grades of multiple metal deposits that will maximize the NPV. At first, the solution space is determined by using the grid search method, then the optimum cutoff grades are determined accurately by the use of genetic algorithm. The result of a sensitivity analysis of the problem shows that when crossover probability ranges between 55 to 70%, and mutation probability is between 8 to 11%, and population size greater than 35 individuals; the optimum cutoff grades can be determined with high accuracy while keeping the computational time relatively low.