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This paper considers a distributed observer design for a class of nonlinear systems with time delays in a network. Specifically, each distributed observer has access to partial output as it communicates with its neighboring observers through consensus protocols defined on the network. The network includes N local observers where adjacent observers transmit and receive information through a delayed telecommunication graph network. The design method is based on Lipschitz condition of nonlinear terms while having time-delay cases in view. Appropriate selection of Lyapunov functions is made and the Jensen inequality applied in delayed nonlinear systems in undirected, strongly connected, and directed networks containing spanning trees. Also, via the design algorithm, the necessary and sufficient conditions for the design of parameters are defined so as to stabilize the error dynamics. Finally, numerical simulations are provided to verify the effectiveness of the proposed method. [ABSTRACT FROM AUTHOR]

Sustainable Development (SD) has played an important role in all industries and mining activities. The Internet of Things (IoT), interacting with industrial machines or home appliances through an interconnected network, can assist in developing real-time platforms for monitoring and operating a complex production system with minimal intervention of humans, which made it possible to benefit from the data obtained to increase production rate, Net Present Value optimization, workforce and machine safety, and decreasing pollution. Ideal automated mining can be achieved by designing an IoT based framework and suitable SD assessment. This research aims to achieve a holistic understanding of the current IoT scenario by conducting a comparative analysis of the prevailing literature regarding IoT applications in the mining and SD area. The results showed that, in the economic index of sustainability, mining activity based on IoT can increase productivity, wealth, income, and GDP and decrease operating expenses, depreciation costs, and total cost. From environmental point of view, a significant reduction in emission and pollution can be obtained. Also, the increase in workforce safety and positive impact on culture and knowledge are the components of the social index of sustainability. These activities are followed by some significant challenges such as developing infrastructures, modern machinery, adequate security for data transmission, increase business in the area, creating new jobs for individuals, especially those who have lost their jobs. It's essential to devise new rules to protect local people, properly distribute the wealth gained from this development to improve the infrastructure of the mining area. [ABSTRACT FROM AUTHOR]

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]

Distribution networks are operated in different conditions and the traditional protection systems might not be proper for all available operation conditions by using directional overcurrent relaying. Besides, the presence of distributed generations makes the protection setting and coordination more complex, and may even make it impossible to access a reliable protection system. Therefore, a fully distributed adaptive protection scheme based on the multi‐agent systems is proposed to improve the reliability, selectivity and sensitivity of relays. It uses only numerical directional overcurrent relays with instantaneous characteristics as agents, so that only need to pick‐up settings and react quickly. All agents dynamically update their pickup value to increase the fault detection sensitivity, and make reliable and selective on‐board decisions for fault location and isolation. In addition, in order to achieve high sensitivity and mitigate miscoordination, using setting groups of relays, a novel adaptive backup protection scheme, which does not need complex computational coordination, is proposed. The proposed system is performed in the distributed manner to enhance efficiency and robustness against cyber‐attacks and one‐point failures. The proposed system is tested on the meshed IEEE 14‐bus system and radial IEEE 13‐bus system with distributed generations to evaluate its performance. [ABSTRACT FROM AUTHOR]

The complexity of the design of the protection system using directional over current relays, for modern power distribution systems has been increased due to the looped/meshed operation and the penetration of distributed generations. Finding a reliable and efficient protection scheme that can be easily implemented in these distribution systems is a major challenge. An efficient solution could be the use of artificial intelligent‐based multi‐agent systems. This paper proposes a novel distributed intelligent based multi‐agent protection scheme, which makes use of current‐only directional over current relays as agents for detecting and locating faults and isolating faulty areas (lines/busbars) in the distribution systems. All agents can make on‐board decisions by exchanging binary data, and do not need a control centre, so the safety of the protection system against one‐point failures and cyber‐attacks is increased. The proposed scheme does not need to exchange analogue data, and, therefore, it prevents the high bandwidth communication links. Moreover, it is free from the traditional coordination between relays. This scheme is implemented on the IEEE‐14 bus and IEEE‐30 bus test systems with the distributed generations and several scenarios have been simulated to evaluate its performance. [ABSTRACT FROM AUTHOR]

The potential of occurrence of coal self-heating is controlled by various properties, both intrinsic and extrinsic. In the intrinsic properties, the maceral content has an important role in influencing its occurrence. This parameter has not been discussed in a comprehensive study among the researchers. Thus, the study of the influence of this parameter on coal self-heating is required. In the present work, the coal self-heating potential was predicted based on the maceral content. A total of 51 coal samples from different underground coal fields in Iran with different percentages of maceral content were collected, and R70 test method was carried out on each coal sample. Then, the regression analysis technique was used for modeling and predicting the coal self-heating potential. For validation and testing, 11 coal samples were randomly gathered from coalfields, and R70 test method was carried on each coal sample and results obtained were compared through a regression analysis. By examining and comparing the results and values obtained from R70 test method and the regression analysis, it was found that increase in the vitrinite and liptinite contents and decrease in the inertinite content increased the coal self-heating potential. [ABSTRACT FROM AUTHOR]

Backbreak (BB) is a detrimental outcome of blasting activities in mineral extraction processes within mines. It involves the development of fractures and cracks at considerable distances behind the last row of blast pits, leading to reduced bench safety and increased operational costs. Given the multitude of factors influencing BB, various techniques have been developed to predict and optimize its occurrence. This particular study focused on analyzing 48 blasts in the tailings section of Gol Gohar Mine No. 1 to forecast BB using the whale optimization algorithm (WOA), multiverse optimizer (MVO), sine cosine algorithm (SCA), ant lion optimizer (ALO), and multivariate linear regression (MLR). Comparative analysis of the four BB prediction models revealed that the MVO algorithm yielded the most favorable outcomes, with the train data exhibiting parameter values of 0.9901, 0.2161, 0.1127, 98.8472, and 0.0180 for R2, RMSE, MSE, VAF, and MAPE, respectively, while the test data displayed values of 0.6357, 1.4955, 1.2003, 63.5472, and 0.1951 for the same parameters. In addition, the analysis specifically emphasized the substantial influence of spacing, burden, and GSI as the primary determinants of the backbreak phenomenon. In stark contrast, however, powder factor, delay time, and joint condition are identified as having negligible effects on backbreak. [ABSTRACT FROM AUTHOR]

This paper presents the computation of the non‐parametric uncertainty model for multi input multi output (MIMO) systems, which is described by normalized coprime factors (NCF) using the frequency response data of the system. This computation is accomplished by minimizing a υ‐gap metric criterion. For this purpose, the problem is formulated to a convex optimization context, such that a semidefinite programming (SDP) can be implemented. Minimization constraints and the normality constraints of coprime factors are converted to linear matrix inequalities (LMI). Thus, by convex optimization algorithms, the semidefinite programming will be optimized. The proposed method can also be used for non‐square multi input multi output systems in a conservative assumption. So, through the first process of optimization, the frequency responses of the normalized coprime factors are derived. Finally, to evaluate the performance of the proposed method in the computation of the normalized coprime factors of a system, the simulated results of this method are compared with those obtained by the other methods for two types of systems. [ABSTRACT FROM AUTHOR]

Spare-part management has a significant effect on the productivity of mining equipment. The required number of spare parts can be estimated using failure and repair data collected under the name of reliability data. In the mining industry, failure and repair times are decided by the operational environment, rock properties, and the technical and functional behavior of the system. These conditions are heterogeneous and may change significantly from time to time. Such heterogeneity can change equipment's reliability performance and, consequently, the required number of spare parts. Hence, it is necessary for effective spare-part planning to check the heterogeneity among the reliability data. After that, if needed, such heterogeneity should be modeled using an adequate statistical model. Heterogeneity can be categorized into observed and unobserved caused by risk factors. Most spare-part estimation studies ignore the effect of heterogeneity, which can lead to unrealistic estimations. In this study, we introduce the application of a frailty model for modeling the effect of observed and unobserved risk factors on the required number of spare parts for mining equipment. Studies indicate that ignoring the effect of unobservable risk factors can cause a significant bias in estimation. [ABSTRACT FROM AUTHOR]

Heat transfer enhancement in thermal systems has great importance in achieving better performances at decreased spaces. In the present work, by combining two passive enhancement methods of using miniaturized channels and utilizing nanofluid, the heat transfer from a heated surface is investigated. In this regard, the thermal performance of an Aluminum minichannel heat sink with rectangular cross-sections was experimentally investigated. The hydraulic diameter of the minichannels is 2 mm. Distilled water, TiO2–water nanofluid, Al2O3-water nanofluid and hybrid Al2O3/TiO2–water nanofluid were used with a volume fraction of 0.5% as coolants. Constant heat flux boundary condition was considered and maintained by a heater with the power of 36 W at the bottom of the heat sink. The effect of different Reynolds numbers ranged from 400 to 1000 on the thermal performance of the heat sink was evaluated. The experimental results indicated significant improvements in thermal characteristics by using nanofluids as a coolant instead of pure water. The convective heat transfer coefficient enhanced up to 16.97% compared to pure water. The wall temperature reduced up to 5 °C with using Al2O3/TiO2–water hybrid nanofluid instead of pure water. [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]

This paper aims to present the stabilization a two-axis gimbal system. The coupling effects and instances of mass unbalance have been considered in the proposed gimbal model; and a direct self-tuning regulator (STR) is utilized to improve the system performance. For this purpose, the parameters of controller polynomials have been calculated through the application of a recursive least square approach. Alternatively, a specific control signal is generated for both elevation and azimuth axes and applied to the gimbal system. The stabilization results of the targeted two-axis gimbal system confirm the effectiveness of the proposed controller for both elevation and azimuth axes. Moreover, an experimental study is implemented on the dynamics modeling and control of a two-DOF gimbal system. The controller algorithm is implemented through Arduino Uno because of its easy compatibility and portability. [ABSTRACT FROM AUTHOR]

Obstructive sleep apnea (OSA) is a common disorder which can cause periodic fluctuations in heart rate. To diagnose sleep apnea, some studies analyze electrocardiogram (ECG) signals by adopting chaos-based analysis. This research is going to specifically focus on whether it is possible to use chaos-based analysis of heart rate variability (HRV) signals rather than using chaotic analysis of ECG signals to diagnose OSA. While conventional studies mostly use chaos-based analysis of ECG signals to detect OSA, here, we apply correlation dimension (CD) as a chaotic index to analyze HRV data in OSA patients. For this purpose, 17 patients with OSA and 9 healthy individuals referred to a sleep clinic in Isfahan/Iran are studied, and their HRV time series were extracted from 1-h ECG signals recorded overnight. The preliminary step to calculate CD is phase-space reconstruction of the system based on HRV time series. Corresponding parameters, including embedding dimension and lag time, are estimated optimally using enhanced related methods, and then CD is calculated using Grassberger–Procaccia algorithm. Moreover, to evaluate our results, detrended fluctuation analysis (DFA), one of the well-known nonlinear methods in HRV analysis to detect OSA, is also applied to our data and the result is compared with those obtained from CD analysis of HRV. CD index with P < 0.005 indicates a significant difference in nonlinear dynamics of HRV signals detected from OSA patients and healthy individuals. [ABSTRACT FROM AUTHOR]

In this study, stabilisation of input‐delay non‐linear systems in the presence of disturbance based on prediction variable is studied. For both disturbance estimation and delay compensation, an extended prediction variable as well as adaptive sliding mode controller are proposed in which the open‐loop system is not required to be stable. In the proposed prediction variable one needs to estimate disturbance in the future. In order to solve this problem a new non‐linear disturbance observer (NDOB) is proposed. Considering the NDOB in the closed‐loop system, the stability analysis of error dynamic is performed. And the asymptotic stability of non‐linear system with input delay is guaranteed for some class of disturbance. Simulation results finally validate the good performance and robustness of the proposed controller based on disturbance observer. [ABSTRACT FROM AUTHOR]

One of the most prevalent and destructive types of cyber-attacks on power systems is the false data injection (FDI) attack. In a false data injection attack, the attacker inflicts large damages on the network by manipulating the measurements. The pivotal solution to opposing this type of cyber-attack is to use phasor measurement units (PMUs). In this paper, a new method is presented to confront the FDI attack by using the optimal placement of PMU instruments. In the proposed algorithm at the beginning, all PMUs placements that achieve network observability are determined using the tabu search (TS) algorithm. Then, from the observable placement vectors, the placements that minimize the possibility of a cyber-attack on the network is identified. For this purpose, a new attack criterion is presented, which is obtained from the adversary strategy in the attack scheme. Since the measurements obtained from the PMUs must be transferred to a phasor data concentrator (PDC) center, the PDC placement also must be determined. In this paper, the optimal placement of PDC is presented by considering the cost of communication infrastructure, because the cost of communication infrastructure between PMUs and PDC is significant. For this purpose, we have used the Kruskal algorithm. The simulations performed on the IEEE 30-bus and 118-bus test system confirm the effectiveness of the proposed method for opposing cyber-attacks and reducing the cost of communication infrastructure. [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]

This paper proposes a cascade high-gain observer for a class of triangular nonlinear systems with large and diverse time delays at states and output equation. Compared with some existing results in the literature, the main contribution is to consider the simultaneous and diverse delays in both states and output and further, to propose a cascade observer in dealing with arbitrarily large delayed measurements. By choosing a suitable Lyapunov-Krasovskii functional, the sufficient condition is presented that guarantees the exponential convergence of observation error to the origin. Simulation results on a numerical example and a practical case study involving inverted pendulum are finally given to illustrate the effectiveness of the proposed approach. [ABSTRACT FROM AUTHOR]

Once the performance characteristics of a system have been determined, engineers are often faced with the task of identifying the critical components. The objective of this identification is to prioritise improvements in the systems and the efforts to bring these about in the areas that will have the most effect on the system's performance. Availability is an important metric, used to assess the performance of complex systems. Having the availability importance measure (AIM), which determines the importance of items regarding the availability of the system, can help designers and managers to improve performance and minimise the life cost of the system. This paper has developed an AIM for complex systems. Thereafter, the application of the developed importance measure is illustrated by a case study. [ABSTRACT FROM AUTHOR]

The stability problem of nonlinear time-delay systems is addressed. A quadratic constraint is employed to exploit the structure of nonlinearity in dynamical systems via a set of multiplier matrices. This yields less conservative results concerning stability analysis. By employing a Wirtinger-based inequality, a delay-dependent stability criterion is derived in terms of linear matrix inequalities for the nominal and uncertain systems. A numerical example is used to demonstrate the effectiveness of the proposed stability conditions in dealing with some larger class of nonlinearities. [ABSTRACT FROM AUTHOR]

Controlling peak side-lobe level (PSL) is of great importance in high-resolution applications of multiple input multiple output (MIMO) radars. In this paper, designing sequences with good autocorrelation properties are studied. The PSL of the autocorrelation is regarded as the main merit and is optimized through newly introduced cyclic algorithms, namely, PSL minimization quadratic approach, PSL minimization algorithm where the smallest rectangular, and PSL optimization cyclic algorithm. It is revealed that minimizing PSL results in better sequences in terms of autocorrelation side lobes when compared with traditional integrated side-lobe level minimization. In order to improve the performance of these algorithms, fast-randomized singular value decomposition is utilized. To achieve waveform design for MIMO radars, this algorithm is applied to the waveform generated from a modified Bernoulli chaotic system. The numerical experiments confirm the superiority of the newly developed algorithms compared to high-performance algorithms in monostatic and MIMO radars. [ABSTRACT FROM AUTHOR]

An improvement for rock engineering system (RES) coding method is done in this paper by using fuzzy systems. A fuzzy expert semi-quantitative coding methodology is designed to assess the cavability of rock mass within the RES framework. The proposed fuzzy method has the advantage of allowing consideration of uncertainties in the RES analysis by using membership functions in comparison with classic expert semi-quantitative coding method that only unique codes are used to quantify the interaction matrix. Since the cavability of the rock mass is one of the fundamental issues for the caving mining method, the presented improved coding method is creatively used to assess the influencing parameters on cavability of rock mass in block caving mines. Fifteen parameters are considered as the main factors modeling the cavability of the rock mass, and the interactions between these parameters are calculated by proposed fuzzy system. Finally in this paper, the parameters, which are dominant or subordinant, and also the parameters, which are interactive, are introduced. The proposed approach could be a simple but efficient tool in evaluation of the parameters affecting the cavability of rock mass in block caving mines and hence be useful in decision making under uncertainties. [ABSTRACT FROM AUTHOR]

A new method is proposed in this article in order to determine a guaranteed interval of time delay in input signal for a class of non-linear control systems with state feedback. This method is based on the stability sufficient condition of a non-linear control system using the Lyapunov direct approach. For this purpose, the dynamic equations of the non-linear input-delayed system are reformulated as a non-linear system without delay, but with delay-dependent coefficients in the state-space description. The control strategy is considered a linear state feedback. Then, by introducing an appropriately related Lyapunov candidate, the stability sufficient condition of the closed-loop system is satisfied, leading to a guaranteed interval of delay according to the state feedback gain. The main results are gathered and proved as a lemma. The effectiveness of this proposed method is investigated by simulating the state feedback control of a non-linear synchronous generator with a delay in input. [ABSTRACT FROM AUTHOR]

Mining methods such as block caving or sublevel caving rely on the characteristics of the rock mass to cave efficiently to fulfill an economical production. The identification of influencing parameters and cavability assessment are, thus, a prime geotechnical focus for all potential caving projects. In the caving operation, many factors, such as natural and induced factors, affect the caving performance. In this study, after discussing the caving process and identifying all effective parameters, the interaction matrix based on the rock engineering system (RES) is introduced to study the influencing parameters in rock mass cavability. The interaction matrix analyzes the interrelationship between the parameters affecting rock engineering activities. As the interaction matrix codes are not unique, probabilistic coding can be performed non-deterministically, allowing consideration of uncertainties in the RES analysis. As a result, the parameters with the highest probability of being dominant or subordinate, and also the parameters with the highest probability of being interactive, are introduced. The proposed approach could be a simple but efficient tool in the evaluation of the parameters affecting the cavability of rock mass in block caving mines and, hence, useful in decision-making under uncertainties. [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]

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]

Roof fall is one of the serious hazards associated with underground coal mining. Roof fall can cause fatal and non-fatal injuries on miners, stoppages in mining operations and equipment breakdowns. Therefore, accurate prediction of roof fall rate is very important in controlling and eliminating of related problems. In this study, the fuzzy logic was applied to predict roof fall rate in coal mines. The predictive fuzzy model was implemented on fuzzy logic toolbox of MATLAB using Mamdani algorithm and was developed based on experts' knowledge and also a database including 109 datasets of roof performance from US coal mines. 22 datasets of this database were used to assess the performance of this fuzzy model. The comparison between obtained results from model and actual roof fall rate showed that the fuzzy model can predict roof fall rate very well. [ABSTRACT FROM AUTHOR]

Ground vibration is an integral part of the rock blasting process in surface mines, which may cause severe damages to structures and plants in the nearby environment. Therefore, its prediction plays an important role in the minimization of environmental impacts. The peak particle velocity (PPV) is an important predictor for ground vibration. In this paper, first a fuzzy logic model was developed to predict PPV based on collected data from blasting events in Sarcheshmeh copper mine, located in the southwest of Iran. The predictive fuzzy model was implemented on the fuzzy logic toolbox of MATLAB using the Mamdani algorithm. Then, the PPV was predicted by conventional empirical predictors used in blasting practice and also by multiple regression analysis. Finally, a comparative analysis between the results obtained by the fuzzy model and common vibration predictors was carried out. The results indicated the high predictive capacity of fuzzy model, which can be used as a reliable predictor of ground vibration for the studied mine. [ABSTRACT FROM AUTHOR]

In this article, the reliability of the cable system of a drum shearer machine was studied and analysed using operation and maintenance data from an Iranian mine for a period of two years. The tests for trend and serial correlation show that the times between successive failures for the cable system are not independent and identically distributed. A goodness-of-fit test shows that the power law process model provides a good fit to the failure data of this system. After parameter estimation for the power law model, reliability and failure rate plots were obtained. Based on analysis and results, a period of 125 h was defined as the reliability-based maintenance interval for the cable system of the shearer. The analysis shows that, by using this strategy, the reliability of the system will improve by at least 50%. [ABSTRACT FROM AUTHOR]

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]

This paper aims to design an attitude controller for a flexible spacecraft under external disturbance and uncertainty. The spacecraft's attitude is controlled by a super twisting controller based on a disturbance observer. This paper's spacecraft system is non-minimum phase since mode-shapes are included in the output; thus, the following four methods are designed to compensate for the constraint: (1) The output redefinition method, where outputs are redefined as a combination of mode-shapes and quaternions. (2) The flexible spacecraft is controlled without measuring the mode-shapes, and only the quaternion parameters are selected as the output. (3) An advanced sliding surface is proposed, in which the mode-shapes are considered in the sliding surface. (4) The difference between flexible and rigid spacecraft dynamics is considered as disturbance, and its effect on the system is compensated. The finite-time stability of the closed-loop system is proved by leveraging the Lyapunov theory. The numerical simulation illustrates the closed-loop system's effectiveness in terms of robustness compared to the existing controller and the four mentioned methods. [ABSTRACT FROM AUTHOR]

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]

These days, the application of electronic power transformers (EPTs) is expanding in place of ordinary power transformers. These transformers can transmit power via three or four wire converters. Their dynamic performance is extremely important, due to their complex structure. In this paper, a new method is proposed for improving the dynamic performance of distribution electronic power transformers (DEPT) by using sliding mode control (SMC). Hence, to express the dynamic characteristics of a system, different factors such as the voltage unbalance, voltage sag, voltage harmonics and voltage flicker in the system primary side are considered. The four controlling aims of the improvement in dynaniic performance include: 1) maintaining the input currents so that they are in sinusoidal form and in phase with the input voltages so they have a unity power factor, 2) keeping the dc-link voltage within the reference amount, 3) keeping the output voltages at a fixed amount and 4) keeping the output voltages in sinusoidal and symmetrical forms. Simulation results indicate the potential and capability of the proposed method in improving DEPT behavior. [ABSTRACT FROM AUTHOR]

In this article, an improved method for eigenvalue assignment via state feedback in the linear time-invariant multivariable systems is proposed. This method is based on elementary similarity operations, and involves mainly utilisation of vector companion forms, and thus is very simple and easy to implement on a digital computer. In addition to the controllable systems, the proposed method can be applied for the stabilisable ones and also systems with linearly dependent inputs. Moreover, two types of state-feedback gain matrices can be achieved by this method: (1) the numerical one, which is unique, and (2) the parametric one, in which its parameters are determined in order to achieve a gain matrix with minimum Frobenius norm. The numerical examples are presented to demonstrate the advantages of the proposed method. [ABSTRACT FROM AUTHOR]

This paper presents a chaos synchronization method for a class of uncertain chaotic systems using the combination of an optimal control theory and an adaptive strategy. A quadratic optimal regulator and an adaptive control are used to represent the controller's structure. The asymptotic stability of the corresponding error dynamical system is guaranteed through Lyapunov stability analysis. The proposed controller is employed in two uncertain chaotic Lu systems, and their promising performances are illustrated. [ABSTRACT FROM AUTHOR]

Abstract: Permanent Magnet Synchronous Motor (PMSM) experiences chaotic behavior for a certain range of its parameters. In this case, since the performance of the PMSM degrades, the chaos should be eliminated. In this Letter, the control of the undesirable chaos in PMSM using Lyapunov exponents (LEs) placement is proposed that is also improved by choosing optimal locations of the LEs in the sense of predefined cost function. Moreover, in order to provide the physical realization of the method, nonlinear parameter estimator for the system is suggested. Finally, to show the effectiveness of the proposed methodology, the simulation results for applying this control strategy are provided. [ABSTRACT FROM AUTHOR]

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]

Among the fossil fuels, coal is the most widely used one all over the world for different purposes and is a stable source of energy. Coal mining has serious hazards such as spontaneous combustion. Many factors can influence the tendency for occurrence of this phenomenon in coal mines and coal storages, one of which is the petrographic characteristics (maceral and pyrite contents). The petrographic characteristics are directly affected by the growth of coalification and origin of coal forming. In this research work, firstly, the maceral and pyrite contents in coal samples were identified in two various mines in Iran (Tabas Parvadeh and Eastern Alborz coal mines). Then the spontaneous coal combustion propensity of each sample was measured using the Crossing Point Temperature (CPT) test method. The aim for carrying out this research work was to measure the effect of the maceral and pyrite contents on the grade of spontaneous coal combustion propensity. It was found that the pyrite contents and the vitrinite, liptinite, and inertinite mean levels in the Tabas Parvadeh and Eastern Alborz coal mines were (2.08%, 53.30%, 9.91%, 34.71%) and (1.14%, 53.06%, 6.39%, 39.41%), respectively. The mean CPT value was 148.43ºC in the Tabas Parvadeh coal mines and 175.86ºC in the Eastern Alborz coal mines. By examining the results of the experiments and comparing the CPT values, it was found that with an increase in the liptinite and pyrite contents and a decrease in the inertinite content, the Tabas Parvadeh coal mines tend to have more tendency for spontaneous coal combustion in comparison with the Eastern Alborz coal mines. [ABSTRACT FROM AUTHOR]

In recent years, the application of the resilience concept has increased in various domains. Resilience depicts the ability of a system to return to its normal operational status after failure events or disruptions. According to the literature survey, there are various studies, which have been done in the field of engineering and non-engineering systems, and there is no study about applying the resilience concept in the field of the mining industry. In this paper, first, the resilience concept is introduced, and the resilience of the mining fleet of Sungun copper mine is estimated later on. For this aim, performance indicators of the system (i.e., reliability, maintainability, and supportability) are used. The results showed that the resilience of the entire system for one hour of its function is equal to 83.1%, and this value decreases to 37.1% after 10 hours. It means if there is a failure in the system, it will have 83.1% and 37.1% probabilities to be resilient against the failure event after 1 hour and 10 hours of system function. [ABSTRACT FROM AUTHOR]

It is an essential task to estimate the remaining useful life (RUL) of machinery in the mining sector aimed at ensuring the production and the customer's satisfaction. In this study, a conceptual framework was used to determine the RUL under the reliability analysis in a frailty model. The proposed framework was implemented on a Komatsu PC-1250 excavator from the Sungun copper mine. Also, the Weibull-frailty model was selected to describe the failure behavior and compare it with the classical-exponential model. The frailty model was also used to evaluate the impact of unobserved environmental conditions on the RUL values. Both applied models were fitted to the obtained data from 80 operational hours of the Komatsu PC-1250 excavator. Plotting the results from the reliability analysis of two models demonstrated that the mine system with the frailty model performs better than the classical model before reaching the reliability of 80%. Besides, the frailty model shows a coherent with the operational time of the excavator, while the classical model demonstrates a sinusoid variation. The obtained results may be used for the development of maintenance, preventive repairs planning, and the spare parts replacement intervals. [ABSTRACT FROM AUTHOR]

The main objective of this paper is observer design for a class of non-linear switched systems, satisfying one-sided Lipschitz condition. The underlying systems may include a larger class of non-linearities with less conservativeness, compared with Lipschitz systems. By the assumption of synchronous switching, a Luenberger-like observer is first designed for state estimation, based on the average dwell time strategy. Then, under asynchronous switching, an observer is proposed with asymptotic convergence property. In addition to theoretical analysis and stability proof, the effectiveness of the proposed observers is presented and discussed via illustrative examples. [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]

Maintenance cost is a significant part of production costs. Hence, logistics and spare part management should be considered early in the design and operational phase. The reliability characteristic of the item can be used effectively to spare part prediction (SPP). In mining industries, the reliability characteristic can be affected significantly by the operational conditions. In this study, to have an accurate SPP, covariate-based reliability models have been used to estimate the required number of tire spare parts for a dump truck fleet. The outputs represent a significant difference in the required spare parts' management, when considering and ignoring covariates. [ABSTRACT FROM AUTHOR]

Many real-world dynamics can be modeled as nonlinear time-delay systems. In order to capture a more realistic model for system dynamics, the exact values of time-delay should be taken into account. For nonlinear time-delay systems, the estimation of delays in both state and output equations is discussed. A cost function is defined based on least-square error between actual and estimated values of the output measurement. The value of time-delays in the nonlinear system are then derived using a gradient-based optimization method. Because of the implicit description of the cost function with respect to the delay value, its gradients cannot be obtained by standard analytical differentiation rules. In this case, the optimal computational methods are utilized to derive two formulas for computing the gradient. An optimization scheme is then formulated to estimate both state and output delays. The effectiveness of the proposed estimation method is finally demonstrated using the simulation results on a benchmark chemical process. [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]

When a system's performance is inadequate, the concept of availability importance can be used to improve it. The availability of an item depends on the combined aspects of its reliability and maintainability. In a system consisting of many subsystems, the availability of some subsystems is more important to system performance than others. The availability measure determines the priority of availability across subsystems. Most researchers only consider operation time and ignore the influence of the operating environment; therefore, their estimations are not accurate enough. In contrast to previous research, we focus on the influence of the operating environment on the system/subsystem's characteristics with a view to prioritizing them based on the importance of availability. The paper considers part of the mining fleet system of Sungun copper mine, including the wagon drill, loader, bulldozer, and dump truck subsystems. We identify an ordered list of possibilities for availability improvement and suggest changes or remedial actions for each item to either reduce its failure rate or reduce the time required to repair it. [ABSTRACT FROM AUTHOR]