Time filter

Source Type

Mikaeil R.,Urmia University of Technology | Ataei M.,Shahroud University Of Technology | Ghadernejad S.,Urmia University of Technology | Sadegheslam G.,Urmia University of Technology
Archives of Mining Sciences | Year: 2014

The system vibration is a very significant measure of the sawing performance, because it indicates the amount of energy required to saw the rock. The maintenance cost of system is also dependant on system vibration. A few increases in system vibration cause a huge increase in the maintenance cost of the system. In this paper, the vibration of system in terms of RMSa was investigated and models for estimation of vibration by means of rock brittleness indexes and operational specifications were designed via statistical models and multiple curvilinear regression analysis. In this study, the relationships between rock brittleness indexes and operational specifications were investigated by regression analysis in statistical package for social science (SPSS) and the results of determination coefficients have been presented. In the second part, the diagrams show that a point lying on the line indicates an exact estimation. In the plot for model, the points are scattered uniformly about the diagonal line, suggesting that the models are good. It is very useful to evaluate the vibration of system and select the suitable operational characteristics by only some mechanical properties of rock.

Monjezi M.,Tarbiat Modares University | Rahmani B.N.,Islamic Azad University at Tehran | Torabi S.R.,Shahroud University of Technology | Singh T.N.,Indian Institute of Technology Bombay
Archives of Mining Sciences | Year: 2012

In this paper, an attempt has been made to use numerical modelling for simulating a long halt in construction process at a shallow depth metro tunnel and investigate the effects of soil nailing to increase the tunnel face strength. Finite difference software FLAC with high applicability in a continuum environment was adopted for this study. The tunnel is being excavated for Tehran metro project. Shield tunnelling with roadheader and back hoe cutting tools is applied in the excavation process. Mohr-Coulomb elasto-plastic constitutive law is considered to model the ground. After two months halting in excavation process, tunnel instability and ground subsidence were recorded in thirteen different monitoring points. Numerical simulation results showed a close approximation (11-16%) between measured and FLAC computed displacements of the tunnel crown in case of unsupported face, which is in close proximity and a proof indicates the reliability of simulation. Also, simulation results exhibit a significant reduction in the ground subsidence and tunnel instability in case of supported face by means of the soil nailing.

Fazeli M.,Amirkabir University of Technology | Osanloo M.,Amirkabir University of Technology | Naghne S.,Shahroud University of Technology
Legislation, Technology and Practice of Mine Land Reclamation - Proceedings of the Beijing International Symposium Land Reclamation and Ecological Restoration, LRER 2014 | Year: 2015

Mine Facility Location Selection (MFLS) is one of the most common encountered problems associated with sustainable development in open pit mine planning. This paper addresses a multistepprocedure to be applied for MFLS. In the first step, the potential areas for the mine facilities are identified through a preliminary screening process with application of the Geographical Information System (GIS). In the second step, a number of discrete candidate sites are identified resulting in finding three to five sites for each facility. In the third step, environmental impacts of each location for each facility are assessed by determining the effect of a comprehensive set of impacting factors on various environmental components. Then, the MFLS problem is formulated and solved by a hub location problem model to minimize the total transportation costs between facilities. The final solution of this procedure, to select the most appropriate locations for mine facilities, not only is technically feasible but also minimizes the cost of the mining project and diminishes the environmental issues of mining activities. This approach was applied to Sangan iron open pit mine of Iran to select primary crusher, processing plant and tailing pond locations and the results are discussed in the paper. © 2015 Taylor & Francis Group, London.

Soroush H.,Weatherford | Rasouli V.,Curtin University Australia | Tokhmechi B.,Shahroud University of Technology
International Journal of Rock Mechanics and Mining Sciences | Year: 2010

Petrophysical logs are usually acquired in most of the drilled wells and some of them have good correlations with mechanical properties of the rock. In this paper, a new multi-variable workflow is proposed in order to identify the location of borehole enlargements along the wellbore in correlation with some of the petrophysical logs acquired using wireline or logging while drilling tools in addition to mud weight and in-situ vertical stress data. This approach employs number of data processing techniques including Bayesian classification, wavelet de-noising, and data fusion to determine borehole intervals with maximum likelihood of enlargement. The application of the proposed method is to identify enlargement zones and does not provide information about stresses orientations and magnitudes. This paper explains the methodology and presents its results in five study wells in a carbonate field. The study confirms the applicability and the generalization capability of the method in carbonate formations with a significant accuracy. © 2010 Elsevier Ltd.

Soroush H.,Weatherford | Tokhmechi B.,Shahroud University of Technology
72nd European Association of Geoscientists and Engineers Conference and Exhibition 2010: A New Spring for Geoscience. Incorporating SPE EUROPEC 2010 | Year: 2010

The integrity of the wellbore plays an important role in petroleum operations including drilling, completion and production. Oil and gas industry has been always suffering from wellbore stability and sand production problems which have been costly and time consuming to tackle. Having a good knowledge of formation strength and earth's stresses is the key for evaluation of well integrity during both drilling and production. Formation strength is usually obtained throught either experimental tests or interpretation of petrophysical logs. However, on one side, in most cases the core strength databases are limited, discontinuous and are often biased towards stronger intervals; on the other side, petrophysical logs can be adversely affected by drilling fluid, pore fluid and borehole shape and require to be calibrated against laboratory measurements. It raised the idea of approximating rock strength from some physical or petrographical properties of rock, which are more convenient to measure, even on drilling cuttings. This paper aims to establish empirical relationships between sandstone petrographical features and the unconfined compressive strength (UCS). A comprehensive laboratory study was performed and reasonable correlations was established between the UCS values and a number of petrographical properties (including cementation degree, grain shape, median grain size. nature of grain-grain contacts, average numbers of grains in contact, quartz content, clay content, sorting, and visual porosity). Finally a multilayer perception neural network (MLPNN) model was designed to enable estimation of UCS using petrographical data. A workflow was presented for near real-time evaluation of formation by visual inspection and characterisation of drilling cuttings at rig-site with implication for controlling wellbore failure during drilling and production. © 2010, European Association of Geoscientists and Engineers.

Kordnaeij A.,Tarbiat Modares University | Salmasi M.,Shahroud University of Technology | Fruzande S.,Business Administration M.Sc
European Journal of Scientific Research | Year: 2011

In today's turbulent economy, it is very important for managers to lead their business effectively and efficiently. Balanced Score Card is one of the most popular approaches for evaluating the firm's performance in implementing formulated strategies and achieving the organization's objectives. Additionally, it is used as a tool for all stages in strategic management process. Balanced Score Card assesses the firm's performance and its motion toward the objectives in four major perspectives: Financial perspective, Customer-Market perspective, Internal Processes perspective and Learning & Growth perspective. There are very limited researches examine the strategy implementation and its effectiveness in Iran. This study aims to examine the effectiveness of formulated strategies. The research is conducted in an Iranian insurance firm. After formulating strategies and implementing them, the data in all four major perspectives were gathered with the Balanced Score Card approach. According to the results of current study, the company was successful in achieving its objectives. It means that they implement the formulated strategies successfully. At the end of the article, there are some implications for managers and some suggestions for the future studies. © EuroJournals Publishing, Inc. 2011.

Monjezi M.,Tarbiat Modares University | Kashani M.R.,Tarbiat Modares University | Ataei M.,Shahroud University of Technology
Arabian Journal of Geosciences | Year: 2013

Grade estimation is very important in designing open pits. In the process of grade estimation, underestimation can result in loss of economic ore, whereas overestimation would unnecessarily increase stripping ratio. Normally, kriging method, which suffers from underestimation and/or overestimation due to smoothing effect, is used for grade estimation. To overcome drawbacks of the kriging method, more efficient techniques such as conditional simulation can be applied. In this paper, utilizing sequential Gaussian conditional simulation, grade models were constructed for Sungun copper deposit situated in the North West of Iran. According to the obtained results, it was observed that conditional simulation can effectively cope with the weakness of kriging method. Also, it was observed that as compared to the kriging method, grade distribution, resulted from the conditional simulation, is almost identical to that of the real exploration data. Accordingly, using conditional simulation, the amount of mineable ore was significantly increased, and also, average net present value as the mines' most important economic indicator was improved by 40%. © 2011 Saudi Society for Geosciences.

Shariati M.,Shahroud University of Technology | Sedighi M.,Shahroud University of Technology | Saemi J.,Shahroud University of Technology | Eipakchi H.R.,Shahroud University of Technology | Allahbakhsh H.R.,Shahroud University of Technology
Mechanika | Year: 2010

In this paper, experimental and numerical buck-ling analysis of steel cylindrical shells of various lengths and diameters with crack have been studied using the finite element method and the effect of crack position, crack ori-entation and the crack length-to-cylindrical shell perimeter (λ = a/2 π r) and shell length-to-diameter (L/D) ratios on the buckling and post-buckling behavior of cylindrical shells have been investigated. For several specimens, buck-ling test was performed using an INSTRON 8802 servo hydraulic machine and the results of experimental tests were compared to numerical results. A very good correla-tion was observed between numerical simulation and ex-perimental results.

Shariati M.,Shahroud University of Technology | Saemi J.,Shahroud University of Technology | Sedighi M.,Shahroud University of Technology | R. Eipakchi H.,Shahroud University of Technology
Strength of Materials | Year: 2011

The effects of the length, sector angle, and different boundary conditions on the buckling load and post buckling behavior of cylindrical panels have been investigated using experimental and numerical methods. The experimental tests have been performed using a servo-hydraulic machine, Instron 8808, and for numerical analysis, Abaqus finite element package has been used. The numerical results are in good agreement with the experimental tests.

Zamani I.,Shahroud University of Technology | Zarif M.H.,Shahroud University of Technology
International Journal of Innovative Computing, Information and Control | Year: 2010

This paper presents a new approach for the stability analysis of Takagi-Sugeno (T-S) fuzzy systems. An idea is investigated to use piecewise quadratic Lyapunov function with low amount of computations. This class of Lyapunov function candidates is much richer than the common quadratic Lyapunov function. By exploiting the piecewise continuous Lyapunov function, we derive stability conditions that can be verified via convex optimization over linear matrix inequalities (LMIs) or bilinear matrix inequalities (BMIs). This idea will be used to derive some sufficient stability conditions for output feedback controller, parallel distributed compensation (PDC) and dynamic parallel distributed compensation (DPDC). Independence of this method of finding only one positive definite matrix that makes this method highly applicable, has less computation. Also, idnependence of these fuzzy sets to be normalized and their shapes make this method more useful. A numerical example which is given illustrates the effectiveness of the proposed method. © 2010 ICIC INTERNATIONAL.

Loading Shahroud University of Technology collaborators
Loading Shahroud University of Technology collaborators