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Surge is a form of dynamic instability created as an unstable pattern in the flow of fluid and can severely affect centrifugal compressor performance by causing fluctuations in flow and pressure parameters. Due to the heavy and costly damage that the surge may cause in various industrial processes such as petrochemical plants, it is necessary to design an appropriate control system to reduce the effect of this phenomenon. The problem of active surge control of a centrifugal compressor using the throttle control valve (TCV) in the presence of compressor parametric uncertainties as well as large demands on upstream and downstream loads is investigated in this work. The control objective was to design a robust control system that can stabilize the compressor over a wide operating range without knowing the upper bound for the uncertainties and load demand. The controller should also react quickly by generating a smooth control signal without saturating the control input. These objectives are achieved by designing a sliding mode controller along with a nonlinear disturbance observer. The performance of the proposed disturbance observer-based controller is evaluated under various operational and load conditions and the results are compared against fuzzy type 1, conventional sliding mode, and wavelet-based neural network robust adaptive controllers. The results show that the proposed method can tolerate large disturbances without any knowledge on the upper bound of the incident disturbance, both on the downstream pressure and upstream mass flow which is highly desirable in practice. The comparative study proves the efficacy of the proposed method using various performance measures. The study also confirms the superior robust performance and stability of the proposed method in front of matched and mismatched disturbances as well as model uncertainties especially close to the instability boundary. Although choosing a TCV actuator has made the control system design easier, the sensitivity of the control valve to flow coefficient and zero calibration under different operating ranges of the compression system is studied carefully and some recommendations for the users are provided. • Active surge control of a compressor in the presence of uncertainty as well as the external disturbances is investigated. • A disturbance observer-based sliding mode controller is proposed to stabilise the compressor system in the surge area. • The nonlinear feedforward disturbance observer is designed to estimate the abrupt changes taking place in the system. • The proposed disturbance observer-based technique is compared with other techniques under various operational conditions. • The robust performance and stability of the method especially close to the instability boundary is proven numerically. [ABSTRACT FROM AUTHOR]

This paper presents an observer for a class of nonlinear systems, suitably affine in the input and the delayed terms, with constant, known, and arbitrarily large time-delays in both internal and output variables. It is assumed that the system at hand is globally drift-observable and that the function describing the dynamics is globally Lipschitz. Moreover, it is assumed that the system at hand admits full uniform observation relative degree. A differential geometry-based approach is followed. The well-known chain procedure is employed in order to deal with arbitrarily large output delay. It is proved that, for any given delays at states and output, there exist a suitable gain matrix and a Hurwitz matrix, involved in the observer algorithm, such that, when a sufficiently large number of chain elements are employed, the observation error converges asymptotically to zero. The effectiveness of the proposed method is illustrated by numerical examples. [ABSTRACT FROM AUTHOR]

Attitude and vibration control of a general form of flexible satellites is addressed in this paper. Partial differential dynamic equations are derived considering new details such as multi sectioned solar panels and elastic connections between main hub and solar panels. Boundary control approach is adopted to eliminate simplification errors of discrete models, using just one actuator in the hub. Asymptotic stability of attitude dynamics is proved for a group of boundary controllers and necessary conditions for asymptotic stability of vibrations are discussed. Being independent of modeling accuracy and using easily measurable feedbacks are among advantages of the proposed class of controllers. Through simulations using FEM technique and a controller with the least number of boundary feedback parameters, good performance of the introduced method is illustrated. • A class of boundary controllers is proposed for attitude and vibration control of flexible satellites. • The least number of easily measurable feedback signals from the boundary can be used. • Asymptotic stability conditions are discussed and illustrated via simulations. • Modeling accuracy does not matter. • Multi-sectioned panels and elastic/viscous connections between panels and the hub are considered. [ABSTRACT FROM AUTHOR]

Asymptotic stabilization of a class of nonlinear systems with known constant long input delay is addressed in the presence of external disturbance by applying sliding mode control method. Modified prediction variable scheme is employed to compensate long delays in the input, where conventional prediction variable approaches cannot be employed. This is mainly due to the fact that the external disturbance appears in the prediction variable, which renders the controller dependent on the external disturbance. In order to tackle this problem, the nonlinear disturbance observer based predictor is used. A suitable disturbance observer is designed to estimate the external disturbance that appears in the prediction variable. Respected to some existing results, the prediction-based control for more general class of the nonlinear systems in the presence of external disturbance is the main contribution of this paper. Actuator and sensor delays exist in the most common dynamic systems. So, the proposed control scheme can be employed in many conventional systems. The simulation results indicate the robustness and efficiency of the proposed controller. • Prediction-based sliding mode control is used for a class of the nonlinear systems. • Design of nonlinear disturbance observer for a class of input-delay nonlinear systems. • The asymptotic stability for prediction variable convergence is proved. • An analysis of the state error is performed for input delay nonlinear systems. • The asymptotic stability of a class of input delay nonlinear system is proved. [ABSTRACT FROM AUTHOR]

Abstract Coal burst is one of the hazardous events that mining engineers have been struggling with it since past decades. This phenomenon has sudden and violent nature and almost occurs without warning. In coal burst events, a high volume of coal pieces ejected violently into the working space. Consequently, coal burst can lead to casualties and severe damages. The interaction between causing factors of coal burst can lead to different triggering mechanisms. In this paper, coal burst was classified based its mechanisms into self-initiated and remotely triggered. Due to the sever coal burst consequences, its occurrence probability analysis is very essential. In this study, combination of fuzzy theory and fault tree analysis have been used for coal burst occurrence probability analysis. Therefore, occurrence of coal burst as a top event in fault tree has been analyzed using fuzzy fault tree analysis. According to the results, occurrence probability values of coal burst with self-initiated and remotely triggered mechanisms are 0.9% and 11.6%, respectively in coal mines. In addition, the critical paths that lead to coal burst are indicated in this study. These paths are composed of important causing factors that known as basic events in fault tree. Therefore, high mining depth along with local mine stiffness lower than coal stiffness make a more critical path for self-initiated coal burst; and the seismic energy release due to the slippage of discontinuities nearby the coal mines make also a more critical path for remotely triggered coal burst. The result can be inspiring for mining engineers which have conflicted with coal burst. [ABSTRACT FROM AUTHOR]

One of the serious environmental concern around the world is heavy metals contamination. They can enter to the environment through human activities such as mining, farming, and factory activities. Soil contamination by heavy metals can affect crops, enter the food chain and threat human health. Therefore, clearance of the soil from these heavy metals is one of the most important environmental issues. Up to now, different strategies are introduced for heavy metals remediation of soil and some of them were briefly reviewed, here. We were mainly focus on the soil remediation from heavy metals which has the highest percentage of abundance in the contaminated soil, namely arsenic, lead, cadmium, nickel, mercury, iron, copper, and zinc by plants (phytoremediation). On the other hand, different kinds of plants, including trees, flowers, grasses, vegetables, and ferns that can help clean these metals from the soil, are introduced. Growth conditions of these plants, such as light and water, were also studied, and it was found that 48% plants require partial sunlight, and 50% of plants grew in moist soil. They were also classified based on their biological ages, and it was found 68% of plants were perennials and had more than two years of lifespan. Among these plants, some of them are capable of capturing several heavy metals simultaneously, and they are called as Valuable Phytoremediation Plants and they are more useful for soil remediation from heavy metals. It seems that present study can help environmental officials and governments to find a sustainable solution to get rid of heavy metals hazardous on mines ecosystem. [Display omitted] • Soil contamination by heavy metals can affect crops, enter the food chain and threat human health. • Different strategies are introduced for heavy metals remediation of soil. • Phytoremediation is considered as an efficient approach to reduce the concentration of heavy metals in soil. • There are some plants capable of capturing several heavy metals simultaneously, and they are called as Valuable Phytoremediation Plants. [ABSTRACT FROM AUTHOR]

Besides intact rock properties, structural parameters of rock mass have strong effect on drilling rate. In this research, 11 different zones of an open pit iron mine were studied precisely to classify the area based on rock drillability point of view. Laboratory tests were conducted on the rock samples to determine strength parameters. Geological mapping of the rock facies was carried out and rock mass structural parameters as joint inclination, spacing, aperture and filling were recorded along with net drilling times of drill holes. Using these data, an empirical relation was developed to predict drilling rate ( DR ) using the rock mass drillability index ( RDi ) and also a relation that can predict uniaxial compressive strength ( UCS ) of rocks in terms of Schmidt hammer rebound values at this mine. In conclusion, all 66 zones of the mine area were classified according to the RDi . It was observed that RDi can reasonably predict drilling rate of rock masses. A new penetration rate model is defined based on the measured data and then compared with previous model of penetration rate from literature. Since the new model which involves not only intact rock mechanical properties but also structural properties of rock masses could attain better predictions in relation to the previous model. [ABSTRACT FROM AUTHOR]

Highlights: [•] We use fault tree analysis for modeling occurrence of undesired events (failures) in cement factory. [•] In this model, we focused on crushing and mixing bed hall department. [•] Analysis of case study extended to system and subsystem levels for each department. [Copyright &y& Elsevier]

Abstract: For the participation of the steam power plants in regulating the network frequency, boilers and turbines should be co-ordinately controlled in addition to the base load productions. Lack of coordinated control over boiler–turbine may lead to instability; oscillation in producing power and boiler parameters; reduction in the reliability of the unit; and inflicting thermodynamic tension on devices. This paper proposes a boiler–turbine coordinated multivariable control system based on improved sliding mode controller (ISMC). The system controls two main boiler–turbine parameters i.e., the turbine revolution and superheated steam pressure of the boiler output. For this purpose, a comprehensive model of the system including complete and exact description of the subsystems is extracted. The parameters of this model are determined according to our case study that is the 320MW unit of Islam-Abad power plant in Isfahan/Iran. The ISMC method is simulated on the power plant and its performance is compared with the related real PI (proportional-integral) controllers which have been used in this unit. The simulation results show the capability of the proposed controller system in controlling local network frequency and superheated steam pressure in the presence of load variations and disturbances of boiler. [Copyright &y& Elsevier]

Abstract: Various empirical procedures have been developed to determine pillar sizing based on back analysis of failed and successful case histories and statistical analysis techniques. Artificial intelligence techniques are now being used as an alternate to statistical techniques. In this study, the fuzzy logic was applied to predict safe pillar sizing in room and pillar coal mines. The model predicts pillar length and width using depth of cover, mining height, panel width, roof strength rating and loading conditions. The predictive fuzzy model was implemented on fuzzy logic toolbox of MATLAB using the Mamdani algorithm and was developed based on a database including 399 datasets from US room and pillar coal mines. Eighty datasets of this database were used to assess the performance of this fuzzy model. The coefficient of determination (R 2), the variance account for (VAF) and the root mean square error (RMSE) were calculated to check the prediction performance of the model. The R 2, VAF and RMSE values were obtained as 89.3%, 89.27 and 1.39 for the pillar width, and 86.6%, 86.4 and 2.77 for the pillar length. These indices revealed that the developed model is suitable for practical use at mines. In addition, the strength of the relationship between the pillar sizing and the five input parameters were evaluated by the cosine amplitude method and the results showed that the most effective parameter on pillar sizing is loading conditions. [Copyright &y& Elsevier]

Abstract: One of the most challenging safety problems in room and pillar coal mines is roof fall phenomena during retreat mining. Roof fall not only causes fatal and non-fatal injuries on miners, stoppages in mining operations and equipment breakdowns, but also results in inefficient recovery of ore reserves. As a result, development of a methodology for risk assessment of roof fall has a remarkable role on safety of retreat mining. In this paper, at first all effective parameters on roof fall during retreat mining are identified and then the role of each parameter on roof fall occurrence is explained. Afterwards, a practical methodology is developed for assessment and control of roof fall risk using semi-quantitative techniques. Finally, this methodology is applied in main panel of Tabas Central Mine, located in the mid-eastern of Iran, and various possible scenarios of retreat mining and corresponding risks are evaluated. [Copyright &y& Elsevier]

Abstract: A new classification system is presented to evaluate and ranking the sawability of carbonate rock. The sawability of carbonate rock is classified into five categories: excellent, good, fair, poor and very poor. The sawability is assumed to depend on the uniaxial compressive strength, Young’s modulus, Mohs hardness, and a new abrasivity index. The FAHP approach is used to determine the weights of the above-mentioned parameters by decision makers. Moreover, in this paper, a new classification system was developed to modify Schimazek’s F-abrasiveness factor. In this new abrasivity classification, each parameter has a different importance coefficient. The new abrasivity index of carbonate rocks can be obtained from this new abrasivity classification system. The calculated sawability index of developed classification is applied for Iranian carbonate rocks to evaluation the energy consumption in rock sawing process. A variety of two groups of carbonate rocks (seven types) were saw using a fully instrumented laboratory sawing rig at different feed rates, peripheral speeds, and depth of cut. Then, a new statistical model was obtained using multiple regression method based on operating parameters and rock sawability index. [Copyright &y& Elsevier]

Abstract: This research is based on the application of stream sediments to mineral exploration. Identifying the geochemical anomalies from background is a fundamental task in exploration geochemistry. This paper applied the element concentration–area (C–A) model, to separating the geochemical anomalies from background based on a fractal approach and for the compilation of geochemical mapping from stream sediment samples (n =620) of the Ahar region (Iran), where some Cu mineralization occurs. Comparisons of the known copper occurrences against the anomalous area created using thresholds from C–A method illustrate these hits. All of known Cu mineralizations and moreover defines two extra Cu anomaly districts. Additional sampling (n =186) around new Cu anomaly confirms this anomaly within the district. [Copyright &y& Elsevier]

In longwall mining method, the stability of the maingate and tailgate gateroads is of great importance because these excavations are used for essential services such as ventilation and transportation. The aim of this paper is to develop a numerical model to investigate the stability of a maingate gateroad named P8-maingate during caving and extraction of P7 and P8 coal panels of Tabas Parvadeh underground mine. Stability analysis is carried out by critical shear strain criterion, zone plasticity conditions, support system efficiency and strength-stress ratio conditions using FLAC3D, a software based on finite difference numerical methods. In the critical shear strain criterion method, the stability analysis is conducted by comparing the shear strain increments of the element in the model and Sakurai critical shear strain. In the second stability analysis method based on zone plasticity, the zones indicating shear plastic failures are the potential instability-causing regions. In the support system efficiency method, the applied load and pressure are compared to the yielding strength of the support systems to check their stability. In the Strength-Stress Ratio (SSR) method, a safety factor is determined for the gates, and the strength versus stress plots of the gates are assessed to control the stability condition. The results of numerical modeling indicate the stability of the P8-maingate using these methods. The modeling results are then compared to the instrumentation data to investigate the consistency where a good agreement was observed. [ABSTRACT FROM AUTHOR]

In this paper, a finite time control method for an uncertain nonlinear system is proposed. An adaptive sliding mode disturbance observer is designed to estimate the disturbance in finite time. The assumptions on the disturbance are relaxed in the sense that, its first derivative upper bound is considered to be unknown and only the order of its second derivative upper bound is known. Based on the output of proposed disturbance observer, a terminal sliding mode control scheme for the uncertain nonlinear system is presented. The designed control law is continuous and nonsingular. Furthermore, compared with some existing sliding mode controllers, the conditions on the controller parameters bounds are relaxed. It is proved that the disturbance observer error as well as the system states converges to the origin in finite time. Finally, the effectiveness of the proposed method is shown by numerical simulations. [ABSTRACT FROM AUTHOR]

Mining industry is closely linked with sustainable development, which leads to positive and negative impacts of this industry on three key principles of sustainable development, including society, economy, and environment. For ideal implementation and integration of sustainable development in the industry, the three principles of sustainability should be simultaneously applied and not sequentially at different stages of the mining life cycle to maximize the opportunities in the mining industry to contribute to comprehensive development. A suitable framework for sustainable development will be created through the interaction of these principles with activities carried out in different stages of mining life cycle and their implementation in the mining projects can be economically profitable, environmentally clean, and socially responsible. In this study, the researchers' comments about the sustainability or unsustainability of the mining industry have been presented, as well as the necessity of integrating sustainable development considerations in mining life cycle, expression of sustainability conditions, necessary measures, and appropriate solutions for each stage. Also, the review of the studies will be discussed. Image 1040513 [ABSTRACT FROM AUTHOR]

In underground excavations and tunneling, several methods used for excavating process. Drilling and blasting is one of these methods, which are globally used for rock excavation due to low investment and high flexibility against ground condition variations. However, negative effects of blasting to the peripheral rock mass around the excavation are inevitable. One of these blasting damages known as overbreak phenomenon and must be predicted and controlled. Many of prediction problems can solve by using multiple regression analysis, but in some issues like mining and tunneling engineering, there are many uncertainties in nature of problems, which engineers cannot overcome these difficulties only using statistical methods. Then, soft computing methods can be curing this difficulty. In this study, 270 datasets were used with adaptive neuro-fuzzy inference system (ANFIS) and ANFIS-particle swarm optimization (PSO) to develop the predictor models. Input variables for models construction were considered tunnel section area; perimeter holes powder factor, specific drilling and spacing to burden ratio of contour holes. Determination coefficient and root mean square values of ANFIS and ANFIS-PSO models were obtained 0.945, 0.077 and 0.961, 0.064 respectively. The results indicate that ANFIS-PSO model showed better performance for overbreak prediction than ANFIS model. [ABSTRACT FROM AUTHOR]

High performance grid-tied inverters have stringent control requirements both under steady-state and under transient conditions. Many different control systems have been applied to grid-tied inverters. However, there are few publications reviewing the literature on these control systems and their classification, particularly with regard to recent developments in this area. In this paper, a review of solutions for the control of grid-tied inverters is carried out. These control systems are compared and classified as implementation platform, reference frame, output filter of inverter, control strategy, modulation method, and controller. The major advantages and disadvantages of these parameters are highlighted and compared. Then, the most important characteristics of these parameters have been presented in a table to show which parameters can be used in various control systems for grid-tied inverters. [ABSTRACT FROM AUTHOR]

In this paper an importance sampling (IS)-based technique is proposed to achieve the blind equalizer and detector for chaotic communication systems. Chaotic signals are generated using nonlinear dynamical systems. These signals have wide applications in communication as a result of their appropriate properties such as pseudo-randomness, large bandwidth, and unpredictability for long time. Based on the different chaotic signal properties, different communication methods such as chaotic modulation, masking, and spread spectrum have been proposed before. In this paper, chaos masking is adopted for transmitting modulated message symbols over an unknown channel, in which the joint demodulation and equalization is a nonlinear problem. Several methods such as extended Kalman filter (EKF), particle filter (PF), minimum nonlinear prediction error (MNPE), have been previously presented for this problem. Here, a new approach, based on Monte Carlo sampling, is proposed to joint channel equalization and demodulation. At the receiver end, importance sampling is used to detect binary symbols according to maximum likelihood (ML) criterion. Simulation results show that the proposed method has better performance, compared to existing methods, especially at low SNR. [ABSTRACT FROM AUTHOR]

Many variables make foundation conditions unpredicted and uncertain in tunnel and underground constructions which could endanger the safety and adversely impact economy of a project. Evaluating and risk assessment of projects such as mechanized tunneling is necessary to manage and respond to the associated risks, hence, identification of risk factors would be required. In this study by contribution of experienced technicians and use of geological study eight (category) levels of risks are considered. Probability and impact factors are used in the ideal risk analysis. Additionally, in this study ideal and some supplementary factors such as uncertainty of estimates and risk manageability are also addressed. Ranking of risks are determined by Multi-Criteria Decision Making (MCDM) techniques like Fuzzy Analytical Hierarchy Process (FAHP). The present research in Golab tunnel is located in the northwest of Esfahan (Iran), shows that squeezing and face tunnel instability have highest level and gas emissions and clogging of clay have the lowest level of risks. [ABSTRACT FROM AUTHOR]

Abstract: Principal Component Analysis (PCA) is used to determine the most effective parameters on the rock mass penetrability by considering their variance ratio in the first principal component. A model is developed for the prediction of rotary drills penetration rate using non-linear multiple regression analysis. Distribution functions for the effective parameters are calculated using measured data from two case studies. Applying the developed penetration rate model, a stochastic analysis is carried out using the Monte Carlo simulation. The proposed method provides a simple and effective assessment of the variability of the penetration rate model and its dependent parameters. Results showed that the PCA and Monte Carlo are suitable techniques for modeling and assessing the variability of rock mass penetrability parameters. According to the developed distribution model, with 90% of confidence level the penetration rate values range 0.2–2.5m/min, which shows the wide possible range of penetration rates for rotary drilling especially in sedimentary (limestone and sandstone bearing magnetite mineral of Golgohar mine) and Sarcheshmeh igneous porphyry rock masses. [Copyright &y& Elsevier]

Abstract: In this article, by using TOPSIS technique we propose a new method for mineral potential mapping that commonly used to exploration mineral deposits. TOPSIS is a practical and useful technique for ranking and selection of a number of externally determined alternatives through distance measures. We used TOPSIS and GIS to providing prospectivity maps for porphyry copper mineralization on the basis of criteria derived from geological, geochemical, and geophysical controls, and remote sensing data including alteration and faults in Ahar-Arasbaran area in North West Iran. This Method allowed a mixture of quantitative and qualitative information with group decision. The results demonstrate the acceptable outcomes for copper porphyry exploration. [Copyright &y& Elsevier]

Abstract: Prediction of flyrock distance has a remarkable role in reduction and control of blasting accident in surface mines. In this paper, at first a new empirical equation for predicting flyrock distance was developed using dimensional analysis. The equation extended based on controllable blasting parameters that compiled from 150 blasting events in Sungun copper mine, Iran. Then, flyrock phenomenon is simulated using this equation and Monte Carlo (MC) method. Results showed that MC is a good means for modeling and assessing the variability of blasting parameters. Finally, sensitivity analysis was conducted to analyze the effects of the controllable blasting parameters on flyrock distance. Based on correlation sensitivity, the most effective parameters were powder factor, stemming and burden. Finally, it should be noted that the proposed flyrock equation and obtained results are site-specific; it should be used only in the Sungun copper mine, and it should not be used directly in other surface mines. [Copyright &y& Elsevier]

Abstract: Underground mining method selection is one of the most crucial decisions that should be made by mining engineers. Choosing a suitable underground mining method to carry out extraction from a mineral deposit is very important in terms of the economics, safety and the productivity of mining operations. The aim of this study is developing a fuzzy model to selection the optimum mining method by using effective and major criteria and at the same time, taking subjective judgments of decision makers into consideration. Proposed approach is based on the combination of fuzzy analytic hierarchy process (FAHP) method with an advanced type of conventional AHP. FAHP is used in determining of the weights of the criteria by decision makers and then rankings of the methods are determined by AHP. The proposed method is applied for Jajarm Bauxite Mine in Iran and finally the most appropriate mining methods for this mine are ranked. [Copyright &y& Elsevier]

• It develops a methodology for critical infrastructure resilience assessment. • Both technical and organizational influencing factors on resilience are considered. • Expert judgment is used to deal with data unavailability. • Fuzzy sets theory is used to capture uncertainty and bias of expert judgment. • The application of the methodology is illustrated by a real case study. Resilience is an emerging concept whose application has increased significantly in managing engineering systems. In order to have an effective resilience management, first, an estimation of the system resilience should be undertaken. However, a lack of historical data and limited information are major challenges for system resilience estimation. The main reason is that most data collection systems are not designed for resilience assessment. Moreover, the available study dealing with resilience assessment have been used different indices to quantify the resilience of critical infrastructures including, robustness, recoverability, etc. These indices can be affected in a complex way by different factors such as operational conditions, protective practices, the recovery process, logistic process, etc. However, the available resilience studies are not so detailed regarding identifying and quantifying these influencing factors. Therefore, this paper aims to develop and apply a practical methodology to estimate resilience based on the combination of expert judgment and fuzzy set theory. By adopting this methodology, factors influencing resilience can be modeled effectively. Finally, the application of the proposed methodology is illustrated for the main fan system of an underground coal mine. [ABSTRACT FROM AUTHOR]

Economic dispatch seeks for the most economical combination of generation units in power system while satisfying bunch of physical and operational constraints. Finding the most economical generation strategy in power markets with several generation zones is crucial for power system operation. Conventional economic dispatch models cannot find the most economical generation schedule in power system with different generation zones. Moreover, the most economical schedule of generation cannot satisfy the environmental expectations. Therefore, compromising between generation cost and environmental issues is unavoidable. In this connection, total emission produces by generation units is taken into consideration as an objective function in concert with generation cost function. Furthermore, different operational constraints including valve-point effect, prohibited operating zones and multi-fuel operation are considered to make the proposed approach more realistic. Considering all these restrictions necessitate solving the proposed problem, i.e. multi-objective multi-area economic dispatch problem, by a reliable and strong optimization algorithm. In this regard, a hybrid evolutionary algorithm based on the shuffle frog leaping algorithm and the particle swarm optimization is proposed to solve the proposed problem. Effectiveness of the proposed hybrid algorithm is verified on different test systems. [ABSTRACT FROM AUTHOR]

Abstract: The main purpose of this study is to compare the many different rock properties in the rock sawability. The comparison was realized with the combination of the analytic hierarchy process (AHP) and Fuzzy Delphi method and also TOPSIS method. The analysis is one of the multi-criteria techniques providing useful support in selecting among several alternatives with different objectives and criteria. FDAHP method was used in determining the weights of the criteria by decision makers and then ranking the sawability of the rocks was determined by TOPSIS method. The study was supported by the results obtained from a questionnaire carried out to know the opinions of the experts in this subject. During the research process, the rock sawability was evaluated in terms of production rate of sawn rock. Prediction of production rate is important in the cost estimation and the planning of the stone plants. The new developed ranking method may be used for evaluating production rate of ornamental stone at any stone factory with different stone. Some factors such as uniaxial compressive strength, Schmiazek F-abrasivity, mohs hardness and Young’s modulus must be obtained for the best production rate ranking. [Copyright &y& Elsevier]

• The noise level can be an indicator to evaluate the performance of drilling tools. • By increasing the hardness of the drilling bits, the produced noise level is less. • By increasing the rock mechanical parameters, the produced noise level is greater. • Multivariate statistical models have good accuracy in predicting the noise level. Rock drilling systems have extensive use in many industries including mining, construction, and oil and water extraction. The process of drilling inevitably creates some noise at the drill-rock collision surface. Loud noises cause serious safety issues in the workplace. Noise level can also be a good indicator of the performance of the drilling tool. This study measured and compared the noise levels created in the drilling environment during the drilling of three types of hard rock, namely Khoshtinat, white Natanz and Nehbandan granites with three types of drill bit with tungsten carbide, Diamond-DLC, and Titanium-Aluminum-Silicon coatings. The software SPSS was used to develop several multivariate linear and nonlinear statistical models for predicting noise level. The results showed that as the mechanical parameters of the drilled rock increased, so did the noise level. Also, in all specimens, as the hardness of the drill bit increased, the noise level generated by drilling decreased. The results of statistical tests showed, at above 90% confidence level, that the developed models can provide reasonably accurate predictions of the noise level to be generated in drilling environments based on the mechanical properties of the drilled rock, the hardness of the drill bit, and operating specifications. [ABSTRACT FROM AUTHOR]

Drilling is an important engineering operation with extensive application in many fields of industry including mining engineering, oil and gas exploration and exploitation, civil engineering, groundwater management, etc. Drill bits must be able to endure enormous stresses that gradually wear them down during the drilling operation. In rock drilling, wear resistance is a key determinant of the drill bit lifetime and hence the drilling cost, thus basically affecting the choice of drilling method for any given rock type. With the advent of new wear-resistant materials, they can be used to improve the resistance of drill bits against wear and erosion. This study investigated the wear resistance of drill bits with tungsten carbide (WC) coating, DLC-Diamond coating, and titanium-silica‑aluminum (TiAlSi) coating when drilling in three types of hard rock, namely Khoshtinat Granite (A 1), White Natanz Granite (A 2) and Nehbandan Granite (A 3). The drilling tests were performed on cuboid specimens using a drilling machine at rotation speeds of 850, 900 and 950 rpm and penetration rates of 12, 18 and 24 mm/min. The results showed that for any fixed drilling conditions, the wear rates of the TiAlSi drill bit in A 1 , A 2 , and A 3 were respectively 48%, 52%, and 60% lower than those of the WC drill bit. In the same rocks, the Diamond-DLC drill bit also showed 42%, 44.25%, and 55% lower wear rates than the WC drill bit. in addition to the observed changes in wear rate of the drill bits, the surface roughness created by these drills represents the optimum performance of the TiAlSi drill bit. It was observed that, as the mechanical properties of the rock (uniaxial compressive strength, Mohs hardness, Schimazek's abrasivity index and Young's Modulus) increased, the tested drill bits showed wider differences in terms of wear resistance. As the TiAlSi drill bit had the lowest wear rate (27%) and after that, the Diamond-DLC drill bit showed a better wear (30%) performance than the WC drill bit (60%). • Making a laboratory-scale device with the ability to change the parameters of operation for drilling tests. • Coating the drill-bit with three layers. • The effect of coating type on wear rate. • The relationship between the mechanical parameters of the rock and the rate of wear of the drill bits. [ABSTRACT FROM AUTHOR]