University of Tehran Journal of Algorithms and Computation 2476-2776 41 3 2013 05 13 روش تلفیقی تحلیل برگشتی گسیختگی شیب‏ها، در توده‏سنگ‎های با درز‏های نزدیک‏ به ‏هم 309 317 7849 10.22059/jac.2013.7849 EN Soda Dehkhoda Hoseein Memarian Abolfazl Mihan Rad Journal Article 2013 05 13 https://jac.ut.ac.ir/article_7849_4e778f3247e49851cefdd0c631518bf6.pdf

University of Tehran Journal of Algorithms and Computation 2476-2776 41 3 2013 05 13 طراحی محدودة بهینه نهایی در معادن روباز با روش‌های اصلاح شدة مخروط شناور دو 297 307 7850 10.22059/jac.2013.7850 EN Reza Khalou Kaka'i Journal Article 2013 05 13 With the advent and wide spread use of computers a number of algorithms have been developed to determine the optimum ultimate pit limits in open pit mining. The main objective of these algorithms is to find groups of blocks that should be removed to yield the maximum overall mining profit under specified economic conditions and technological constraints. The most common methods are: Lerchs and Grossmann algorithm based on graph theory, the Korobov algorithm, floating or moving cone method, moving cone II and dynamic programming. Among these, the Lerchs-Grossmann algorithm is the only method that always yields the true optimum pit. The disadvantages of the algorithm are complexity of the method and require more computing time than other methods to find out optimum pit outline. The floating cone approach which does not yield a true optimum pit in some cases is the most popular and simplest method and requires significantly less computing time than any other method to reach a solution. The moving cone II has been developed by Wright to overcome the shortfalls of the floating cone method. In this paper the moving cone II has been evaluated for being as a true optimum open pit design method and also two algorithms has been proposed for modification of this method. For this purpose C++ computer programs have been developed under Windows operating system for these algorithms and their results are compared with the Lerchs and Grossmann method, which is the true optimum open pit design algorithm. The outcomes show that these algorithms are able to produce good results. https://jac.ut.ac.ir/article_7850_96bf196faffea9bf3add6ff603fac1ad.pdf

University of Tehran Journal of Algorithms and Computation 2476-2776 41 3 2013 05 13 بهینه‏سازی تخصیص و گسیل کامیون در سامانه ترابری معدن مس سرچشمه 287 296 7851 10.22059/jac.2013.7851 EN Sajjad Haghir Chehreh Ghani Ali Asghar Khodayari Mohammad Farough Hosseini Journal Article 2013 05 13 https://jac.ut.ac.ir/article_7851_12d7dadd03e8c6a971720ef311353bbc.pdf

University of Tehran Journal of Algorithms and Computation 2476-2776 41 3 2013 05 13 بررسی تحلیل دینامیکی و تصحیح قیود تماس نقطه به وجه با استفاده از روش لاگرانژ 273 285 7852 10.22059/jac.2013.7852 EN Seyyed Amir Reza Beyabanaki Ahmad Jafari Journal Article 2013 05 13 In this paper, first the validity of 3-D DDA is examined by comparing its solution for dynamic block displacement with analytical solution. Displacement of a single block on an inclined plane subjected to a dynamic loading is studied for analytical solution with respect to the frictional resistance offered by the inclined slope. 3-D DDA predicts accurately the analytical displacements. The modification of point-to-face contact constraints is also studied too. In the original 3-D DDA method, block contact constraints are enforced using the penalty method. This approach is quite simple, but may lead to inaccuracies which may be large for small values of the penalty number. The penalty method also creates block contact overlap which violates the physical constraints of the problem. These two limitations are overcome by using the Augmented Lagrangian Method which has been programmed in VC++ and its implementation into the 3-D DDA is presented by an illustrative example. This method has been found to model block contact quite well. https://jac.ut.ac.ir/article_7852_0edb54b83fde8e8c1c1fcc2fad01e6c7.pdf

University of Tehran Journal of Algorithms and Computation 2476-2776 41 3 2013 05 13 پیش‌بینی تولید ماسه با استفاده از مدلسازی عددی 263 271 7853 10.22059/jac.2013.7853 EN Sa'eed Badagh Abadai Mehdi Moosavi Jalal Moosavi Journal Article 2013 05 13 Mansuri oil field, which is located at the South-West of Iran, has sand production problem and primary analyses proved the existence of this phenomenon in this field. Generally, there are three methods to evaluate the sand production state which are empirical, numerical, mathematical, and physical. Considering the numerical capability to analyze complex geometries under high stresses condition, FLAC3D, which is a three-dimensional explicit finite-difference program for engineering mechanics computation, was employed to analyze sand production in this field. First, the numerical model was calibrated using designed physical model and then, producing intervals and their perforations were modeled by numeric software. Its results showed that not only end-perforation instability is not the sole dominant mechanism in sand production, but also the effect of adjacent perforations on each other is more important. In this respect, there is an optimum pressure that causes perforations failure and catastrophic sand production. Mansuri field analyses demonstrated that the downhole pressure at its wells is near predicted optimum pressure and producing intervals are going to catastrophically produce sand. https://jac.ut.ac.ir/article_7853_fa8f1e46ec5121bd3688785b1f2f15ae.pdf

University of Tehran Journal of Algorithms and Computation 2476-2776 41 3 2013 05 13 تعیین تیپ سنگی با استفاده از دسته‌بندی چندبعدی داده‌های لاگ 363 367 7854 10.22059/jac.2013.7854 EN Vahid Tavakkoli Abdolhossein Amini Journal Article 2013 05 13 Well logs are principal sources of subsurface geological information. They provide significant information on mineralogical composition, texture, sedimentary structures and petrophysical properties such as porosity and permeability. By compiling data from various well logs, one can discriminate sedimentary units with comparable log characteristics. Sedimentary units with similar fluid flow and capacity are named rock type. Rock type determination is the most important task in reservoir characterization of oil bearing formations. Rock type may be determined using different data sets but their definition on the basis of wire line logs is most common. Multivariate cluster analysis (as the best method of data grouping) is one of the most accurate and effective methods in oil bearing reservoir zonation. The method is applied on both detrital and carbonates rocks. This method gets more support by improvements in algorithms and statistics. Proper combination of logs and appropriate algorithm will increase the accuracy, reliability and effect of the method. Similar faces may have different log responses due to diverse factors that affect the logs. Since using statistical methods and procedures are mandatory, in clustering procedure data are grouped with minimum distance and maximum homogeneity. It is obvious that distinct geological parameters can be related to a group of data, which are to be used by geologists for further interpretation. For this calculation, all log readings are considered as "observations" and the used logs as the "values of the observations". There are several ways to compute the distance between objects. The "Standardized Euclidean" distance is used here in form the MATLAB software, because more accurate results are obtained with this procedure. By grouping log data in multidimensional space (equal dimensions with number of logs), each point (reading) can be related to a group of data (rock type). High resolution rock typing with reliable conclusions can be inferred with this procedure using pure mathematical formula in which there is no need to regression equations or trainings. In this method, any geological parameter described from other sources such as cores and thin sections can be related to wells with comparable rock types. The accuracy and reliability of defined rock types can be examined in wells from which suitable cores are available. Results from such a comparison provide a fundamental base for study of wells with poor core and cutting data. Using MATLAB software, this study testifies a new simple method for rock type determination of Asmari Formation in Marun Field. The reliability of the method is examined by correlation of the resultant rock types with those of inferred from cores. Result from such a correlation indicates the reliability of method in rock type determination. https://jac.ut.ac.ir/article_7854_53bd9d22bae827416b065add4231d14b.pdf

University of Tehran Journal of Algorithms and Computation 2476-2776 41 3 2013 05 13 ارائه روشی جدید برای طراحی الگوی چال های انفجار در معادن روباز 355 361 7855 10.22059/jac.2013.7855 EN Hassan Moomivand Journal Article 2013 05 13 A comprehensive investigation was carried out to minimize the cost price of the rock fragmentation process including: drilling, blasting, secondary blasting and separating the large boulders (oversize rocks) while loading, until the optimized fragmentation, powder factor and ratio of burden (B) to blasthole diameter (?h) were achieved by doing several stages of drilling and blasting practically in different mines. The complicated in situ factors control rock fragmentation by blasting, as development of an adequate method for design of drilling and blasting had been a difficult task. Rock mass parameters affecting the powder factor and ratio were investigated extensively in different mines and discontinuity plane aperture of rock mass as a new parameter affecting the powder factor and ratio was also applied. Parameters affecting the rock mass fragmentation were summarized to be discontinuity plane aperture, discontinuity plane spacing, discontinuity plane orientation, rock mass description and unconfined compressive strength of rock material. The quantitative effect of each parameter on ratio was indicated by a number (rating). The total values of numbers were named “rock fragmentation index” (RFI). The numbers were arranged in a way that RFI was equal to ratio. Parameters of RFI and their rating were proposed in a table to use as a new simple method of blasthole pattern design. https://jac.ut.ac.ir/article_7855_06534fa5b5deb32a8908c4f77fc88a4f.pdf

University of Tehran Journal of Algorithms and Computation 2476-2776 41 3 2013 05 13 فروشویی شیمیایی آلومینا از گل قرمز با بررسی اثر مجزا و ترکیبی اسیدهای آلی و معدنی 343 353 7856 10.22059/jac.2013.7856 EN Yousef Ghorbani Manouchehr Oliazadeh Ahmad Reza Shahverdi Atena Pirayegar Journal Article 2013 05 13 https://jac.ut.ac.ir/article_7856_8b3f32bd739248886502bb97ac568f4f.pdf

University of Tehran Journal of Algorithms and Computation 2476-2776 41 3 2013 05 13 چگونگی تاثیر ابعاد نمونه بر ویژگی های الاستیک دینامیک سنگ 333 342 7857 10.22059/jac.2013.7857 EN Mohammad Farough Hosseini Soroush Fouladchi Mojtaba Ganji Journal Article 2013 05 13 Wave propagation is used as an advanced tool of determining elastic properties of rocks. In spite of being cheap and non destructive tests of rock mechanics, due to its modernity method is not yet replacing the traditional dear and destructive tests. In order to pave ways of replacing this test and making best use of it all effective factors of such method are to be assessed. One fundamental factor affecting the test result is the shape of the specimen tested. The existing standards do not seriously take the sample shape into consideration. It was pointed out elsewhere that in spite of popular taught elastic dynamic properties do vary seriously due to variation of sample shape (height to diameter ratio). As this fact was revealed for limestone in our previous investigation this assessment was extended to other types of rocks for the possibility of true judgment. Therefore, ultrasonic wave propagation tests were conducted on four various rock types with height to diameter ratio of 0.5 to 3. Analyzing of the test results showed that shear wave velocity and elastic dynamic constants are noticeably dependent on sample height/diameter ratio. The variation of height/diameter ratio from 0.5 to 3 caused the variation of shear wave velocity and Poisson’s ratio up to 70%, Elasticity modulus up to 160% and shear modulus up to 200% as follows in details: Variation in shear wave velocity: Limestone, 24%; Siltstone, 70%; Green Tuff, 17% and Granodiorite, 20%. Variation in dynamic elastic modulus: Limestone, 26%; Siltstone, 65%; Green Tuff, 73% and Granodiorite, 33%. Variation in Poisson’s ratio: Limestone, 45%; Siltstone, 160%; Green Tuff, 20% and Granodiorite, 35%. Variation in shear modulus: Limestone, 53%; Siltstone, 200; Green Tuff, 38% and Granodiorite, 45%. It was also observed that the longitudinal wave velocity was not following the height/diameter ratio and showed no specific trend of variation. As seen from the above details, the variation of modulai is much grater for siltstone in compares to the 3 other rocks. It is most likely that this obvious difference is due to inhomogenity of the siltstone texture which causes different behavior in this particular rock. https://jac.ut.ac.ir/article_7857_202345ca6f60393ff5cdb9ff198c9bc4.pdf

University of Tehran Journal of Algorithms and Computation 2476-2776 41 3 2013 05 13 بلوغ حرارتی، کیفیت و نوع ماده آلی در رسوبات شیلی سازند سیلیسی- آواری شمشک، البرز شرقی و مرکزی، شمال ایران 319 332 7858 10.22059/jac.2013.7858 EN Ali Shekari Fard Kazem Seyyed Emami Fransua Boden Journal Article 2013 05 13 https://jac.ut.ac.ir/article_7858_2b8ae6bb6b24470626936680ae89ca4c.pdf