Search for: hydraulics
0.01 seconds
Total 319 records

    Numerical Modeling of Solid Transport in a Transparent Fracture

    , M.Sc. Thesis Sharif University of Technology Shad, Ehsan (Author) ; Shad, Saeed (Supervisor) ; Zivar, Davood (Co-Supervisor)
    Hydraulic fracturing, as an industry-leading technology, has proven to be very efficient in increasing the productivity of oil and gas wells. Therefore, this technology has been taken into attention in recent years and the number of hydraulic fracturing operations has been increasing. In order to enhance the efficiency of this technology, the final transmissibility of the fracture needs to be at the maximum possible value. To do so, proppant injection is the most common way to maintain a fracture open. To achieve a successful hydraulic fracture operation, detailed knowledge of the particle's transport and distribution inside the fracture is needed.In this study, a static fracture geometry... 

    Technical note Variable moderation high performance light water reactor (VMHWR)

    , Article Annals of Nuclear Energy ; Volume 58 , 2013 , Pages 1-5 ; 03064549 (ISSN) Jahanfarnia, G ; Tashakor, S ; Salehi, A. A ; Abbaspour Tehrani Fard, A ; Sharif University of Technology
    A new flow model of high performance light water reactor (HPLWR) is discussed in the present study. HPLWR involves a negative density reactivity coefficient with high time delay. This factor decreases the stability of such reactors when transient and abnormal accidents happen. A new design for enhancing safety and efficiency in such reactors is presented. In the new design, the fluid passing through the moderator channels and the assembly gaps (known as a moderator) flows in channels detached from coolants. It is possible to control the moderator mass flux. Increasing or decreasing the moderator mass flux will modify the moderation capacity, which results in a change in the reactor power.... 

    System and method for analysis of involving factors in the demisting cyclone efficiency

    , Article ASME International Mechanical Engineering Congress and Exposition, Proceedings (IMECE), San Diego, CA ; Volume 15 , November , 2013 ; 9780791856444 (ISBN) Najafabadi, M. M ; Ehteram, M. A ; Ahmadian, M. T ; Barari, A ; ASME ; Sharif University of Technology
    American Society of Mechanical Engineers (ASME)  2013
    In this study a system for real-time analysis of some involving factors in the efficiency of gas-liquid separators is developed based on the weighing method. An ultrasonic atomizer generates water drops in a size range of 1-10 μm with the same frequency during the test. A cyclone separator is selected and effect of the developing flow rate and shape of the mini-riser as a part of connecting assembly to the cyclone separator is investigated. Further an efficient electrostatic precipitator (ESP) with outcome of single-phase airflow is employed in the downstream of the cyclone to separate remaining droplets and produce the same pressure loss during the test. Circular, triangular, rectangular... 

    Neutronic analysis of HPLWR fuel assembly cluster

    , Article Annals of Nuclear Energy ; Volume 50 , December , 2012 , Pages 38-43 ; 03064549 (ISSN) Tashakor, S ; Salehi, A. A ; Jahanfarnia, G ; Abbaspour Tehrani Fard, A ; Sharif University of Technology
    In the present study the neutronic analysis of fuel assembly cluster of the HPLWR is discussed. Neutronic calculations are performed using WIMS-D4 and CITATION codes. Thermal-hydraulic code containing the properties and specifications of the fuel assembly of HPLWR is utilized. The calculated axial power in each selected control volume is used in the thermal-hydraulic code to get the properties of the fluid and fuel needed for further neutronic analysis. The process of coupling continues until convergence is achieved. Finally, the obtained neutronic results including axial power distribution, neutron flux, and power peaking factors are discussed in the present article  

    A new method to calculate efficiency of randomly-packed distillation columns and its comparison with the methods utilized in ASPEN Plus

    , Article Fuel Processing Technology ; Volume 96 , 2012 , Pages 65-73 ; 03783820 (ISSN) Sadeghifar, H ; Sadeghifar, A ; Sharif University of Technology
    In this paper, a unique and applicable method was developed for calculation of efficiency (and mass and heat transfer coefficients) of randomly-packed distillation columns. This method has potential advantages; e.g., unlike all the available methods, it can calculate efficiency without using any empirical mass transfer and hydraulic correlations, and without the need to estimate the operational and hydraulic parameters of an operating column. It, therefore, will be free of errors and limitations of such empirical items and can be used for efficiency calculation of any random packing including new ones. Along with an analysis of the proposed method, the paper also presents a thorough analysis... 

    Manifold coarse graining for online semi-supervised learning

    , Article Lecture Notes in Computer Science (including subseries Lecture Notes in Artificial Intelligence and Lecture Notes in Bioinformatics), 5 September 2011 through 9 September 2011 ; Volume 6911 LNAI, Issue PART 1 , September , 2011 , Pages 391-406 ; 03029743 (ISSN) ; 9783642237799 (ISBN) Farajtabar, M ; Shaban, A ; Rabiee, H. R ; Rohban, M. H ; Sharif University of Technology
    When the number of labeled data is not sufficient, Semi-Supervised Learning (SSL) methods utilize unlabeled data to enhance classification. Recently, many SSL methods have been developed based on the manifold assumption in a batch mode. However, when data arrive sequentially and in large quantities, both computation and storage limitations become a bottleneck. In this paper, we present a new semi-supervised coarse graining (CG) algorithm to reduce the required number of data points for preserving the manifold structure. First, an equivalent formulation of Label Propagation (LP) is derived. Then a novel spectral view of the Harmonic Solution (HS) is proposed. Finally an algorithm to reduce... 

    Hydraulic performance of drain pipe in a submerged tank

    , Article Urban Water Management: Challenges and Oppurtunities - 11th International Conference on Computing and Control for the Water Industry, CCWI 2011, 5 September 2011 through 7 September 2011, Exeter ; Volume 1 , 2011 ; 0953914089 (ISBN) ,9780953914081 (ISBN) Nabaei, M ; Mahmoud Borghei, S ; Sharif University of Technology
    The hydraulic performances of drain pipes are very important in drainage projects and systems. Usually these pipes are used in a saturated soil to decrease the water table to a favorable level or, drain the excess water. However, drain pipes can be used in a water or wastewater tank for different purposes such as selective withdrawal. There are not much published documents on the performance of drain pipes in submerged situations. Therefore, the aim of this study was to examine the performance of drain pipe in a submerged tank. For this, a horizontal pipe of 26.5 mm inner diameter, 5 meter long with 48 circular drain inlets of 10 mm diameter at equal distances along the pipe have been tested... 

    An applicable method for efficiency estimation of operating tray distillation columns and its comparison with the methods utilized in HYSYS and Aspen Plus

    , Article Heat and Mass Transfer/Waerme- und Stoffuebertragung ; Volume 51, Issue 10 , October , 2015 , Pages 1393-1402 ; 09477411 (ISSN) Sadeghifar, H ; Sharif University of Technology
    Springer Verlag  2015
    Developing general methods that rely on column data for the efficiency estimation of operating (existing) distillation columns has been overlooked in the literature. Most of the available methods are based on empirical mass transfer and hydraulic relations correlated to laboratory data. Therefore, these methods may not be sufficiently accurate when applied to industrial columns. In this paper, an applicable and accurate method was developed for the efficiency estimation of distillation columns filled with trays. This method can calculate efficiency as well as mass and heat transfer coefficients without using any empirical mass transfer or hydraulic correlations and without the need to... 

    Investigating the propagation noise in PWRs via closed-loop neutron-kinetic/thermal-hydraulic noise calculations

    , Article Annals of Nuclear Energy ; Volume 80 , 2015 , Pages 101-113 ; 03064549 (ISSN) Malmir, H ; Vosoughi, N ; Sharif University of Technology
    Elsevier Ltd  2015
    Neutron noise induced by propagating thermal-hydraulic disturbances (propagation noise for short) in pressurized water reactors is investigated in this paper. A closed-loop neutron-kinetic/thermal-hydraulic noise simulator (named NOISIM) has been developed, with the capability of modeling the propagation noise in both Western-type and VVER-type pressurized water reactors. The neutron-kinetic/thermal-hydraulic noise equations are on the basis of the first-order perturbation theory. The spatial discretization among the neutron-kinetic noise equations is based on the box-scheme finite difference method (BSFDM) for rectangular-z, triangular-z and hexagonal-z geometries. Furthermore, the finite... 

    Distinguishing attack on bivium

    , Article Proceedings - 10th IEEE International Conference on Computer and Information Technology, CIT-2010, 7th IEEE International Conference on Embedded Software and Systems, ICESS-2010, ScalCom-2010, 29 June 2010 through 1 July 2010, Bradford ; 2010 , Pages 1075-1078 ; 9780769541082 (ISBN) Noferesti, Z ; Rohani, N ; Mohajeri, J ; Aref, M. R ; Sharif University of Technology
    Bivium is a simplified version of Trivium, a hardware profile finalist of eSTREAM project. Bivium has an internal state of size 177 bits and a key length of 80 bits. In this paper we introduce a distinguishing attack on this cipher. In this method we first find the best linear approximation for the updating function. Then by using this approximation, and optimizing the time delay, we find the distinguisher. The complexity of the attack is O(230.79), which is an improvement to the previous distinguishing attack with a complexity of order O(232)  

    High-throughput stream categorization and intrusion detection on GPU

    , Article 8th ACM/IEEE International Conference on Formal Methods and Models for Codesign, MEMOCODE 2010, 26 July 2010 through 28 July 2010 ; August , 2010 , Pages 81-84 ; 9781424478859 (ISBN) Khabbazian, M. H ; Eslamiy, H ; Totoniy, E ; Khademy, A ; Sharif University of Technology
    We present a design and implementation of a high-throughput deep packet inspection performing both stream categorization and intrusion detection on GPU platform using CUDA. This implementation is capable of matching 64 ethernet packet streams against 25 given regular expressions at 524 Mb/s rate on a computer system with GeForce GTX 295 graphic card  

    A steady-state saturation model to determine the subsurface travel time (STT) in complex hillslopes

    , Article Hydrology and Earth System Sciences ; Volume 14, Issue 6 , Jun , 2010 , Pages 891-900 ; 10275606 (ISSN) Sabzevari, T ; Talebi, A ; Ardakanian, R ; Shamsai, A ; Sharif University of Technology
    The travel time of subsurface flow in complex hillslopes (hillslopes with different plan shape and profile curvature) is an important parameter in predicting the subsurface flow in catchments. This time depends on the hillslopes geometry (plan shape and profile curvature), soil properties and climate conditions. The saturation capacity of hillslopes affect the travel time of subsurface flow. The saturation capacity, and subsurface travel time of compound hillslopes depend on parameters such as soil depth, porosity, soil hydraulic conductivity, plan shape (convergent, parallel or divergent), hillslope length, profile curvature (concave, straight or convex) and recharge rate to the groundwater... 

    Experimental investigation of clear-water local scour of compound piers

    , Article Journal of Hydraulic Engineering ; Volume 136, Issue 6 , June , 2010 , Pages 343-351 ; 07339429 (ISSN) Ataie Ashtiani, B ; Baratian Ghorghi, Z ; Beheshti, A. A ; Sharif University of Technology
    Local scour around complex piers under steady clear-water condition was studied experimentally for a variety of configuration, including different sizes and shapes of complex piers. A total of 70 experiments were carried out. Three sets of experiments were performed over the entire range of possible pile cap elevations for complex piers with different geometrical characteristics. The collected data are used to quantify the pile cap elevations that maximize or minimize the local scour depth. Some of the available methodologies to estimate the maximum local scour depth around such complex piers are evaluated. The predictions of the scour depths improved by using the revised methods of... 

    A practical distinguisher for the Shannon cipher

    , Article Journal of Systems and Software ; Volume 83, Issue 4 , 2010 , Pages 543-547 ; 01641212 (ISSN) Ahmadian, Z ; Mohajeri, J ; Salmasizadeh, M ; Hakala, R. M ; Nyberg, K ; Sharif University of Technology
    In this paper, we present a practical linear distinguisher on the Shannon stream cipher. Shannon is a synchronous stream cipher that uses at most 256-bit secret key. In the specification for Shannon, designers state that the intention of the design is to make sure that there are no distinguishing attacks on Shannon requiring less than 280 keystream words and less than 2128 computations. In this work we use the Crossword Puzzle attack technique to construct a distinguisher which requires a keystream of length about 231 words with workload about 231  

    An X-FEM implementation of hydro-fracture growth in naturally fractured saturated porous media

    , Article Poromechanics 2017 - Proceedings of the 6th Biot Conference on Poromechanics, 9 July 2017 through 13 July 2017 ; 2017 , Pages 2027-2034 ; 9780784480779 (ISBN) Vahab, M ; Khoei, A. R ; Khalili, N ; Sharif University of Technology
    In this paper, a coupled hydro-mechanical formulation is developed for the simulation of interaction between hydraulic fractures and natural discontinuities within saturated porous media. The momentum balance equation of the bulk together with the momentum balance and continuity equations of the fluid phase are employed to obtain the fully coupled set of governing equations. The hydro-fracture is modeled for fluid flow using the Darcy law. The natural discontinuity on the other hand is modeled for both opening and closing modes which induce fluid flow and/or contact behavior along the crack edges. The discontinuity in the displacement field is incorporated by using the Heaviside enrichment... 

    Model-based fuzzy control of a gas turbine coupled with a dynamometer

    , Article Journal of Propulsion and Power ; Volume 34, Issue 5 , 2018 , Pages 1178-1188 ; 07484658 (ISSN) Banazadeh, A ; Abdollahi Gol, H ; Sharif University of Technology
    American Institute of Aeronautics and Astronautics Inc  2018
    This paper discusses a novel and detailed approach for dynamic modeling and control design of a coupled hydraulic dynamometer/turbine-engine system. This study presents a comprehensive model to reveal the coupling effects and an adaptive multiobjective controller to ensure a safe and reliable operation. A fuzzy-based strategy is employed to dynamically adjust the controller gains to keep the state variables and power loading within the desirable operational limits. This approach uses the dynamometer inlet, outlet, and trim valves as well as the turbine fuel flow rate and bleed valve in order to control the system performance during the engine testing process. The proposed fuzzy control... 

    A correlated fracture network: modeling and percolation properties

    , Article Water Resources Research ; Volume 43, Issue 7 , 2007 ; 00431397 (ISSN) Masihi, M ; King, P. R ; Sharif University of Technology
    We present a model of fractures based on the idea that the elastic free energy due to the fracture density follows a Boltzmann distribution. The resulting expression for the spatial correlation in the displacement of fractures is used as an objective function in a simulated annealing algorithm to generate realizations of correlated fracture networks. This approach determines the appropriate statistical distribution for the fractures (e.g., length distribution) rather than imposing them as is done conventionally. The model consists of two families of parallel fractures which are perpendicular under isotropic conditions. There also exists a positive correlation between the position of... 

    Assessment of desulfurization of natural gas by chemoautotrophic bacteria in an anaerobic baffled reactor (ABR)

    , Article Chemical Engineering and Processing: Process Intensification ; Volume 45, Issue 3 , 2006 , Pages 232-237 ; 02552701 (ISSN) Amirfakhri, J ; Vossoughi, M ; Soltanieh, M ; Sharif University of Technology
    The purpose of this study is to evaluate an anaerobic system (ABR) cultured by chemoautotrophic bacteria for biodesulfurization of natural gas. In this study anaerobic baffled reactor with five compartments and active volume of 10 l was used. For increasing solid retention time, reactor was packed by pumice with 0.5-2 cm diameter which active volume decreased to 9 l. Inoculation was performed by activated sludge from municipal sewage treatment, which was kept in anaerobic condition for 1 year. The synthetic wastewater which contains S2O32- ion was used in start-up and S -2 for running of ABR. Performance of the reactor was evaluated at three equivalent hydraulic retention times (HRT) of 50,... 

    Numerical modeling of flow over a dam spillway

    , Article 2006 ASME Joint U.S.- European Fluids Engineering Division Summer Meeting, FEDSM2006, Miami, FL, 17 July 2006 through 20 July 2006 ; Volume 1 SYMPOSIA , 2006 , Pages 343-349 ; 0791847500 (ISBN); 9780791847503 (ISBN) Saeedpanah, I ; Shayanfar, M ; Jabbari, E ; Mohammadi, M. H ; Sharif University of Technology
    American Society of Mechanical Engineers  2006
    Free surface flows are frequently encountered in hydraulic engineering problems including water jets, weirs and around gates. An iterative solution to the incompressible two-dimensional vertical steady Navier-Stokes equations, comprising momentum and continuity equations, is used to solve for the priori unknown free surface, the velocity and the pressure fields. The entire water body is covered by a unstructured finite element grid which is locally refined. The dynamic boundary condition is imposed for the free surface where the pressure vanishes. This procedure is done continuously until the normal velocities components vanish. To overcome numerical errors and oscillations encountering in... 

    Parameters affecting turbulent film cooling reynolds-averaged navier-stokes computational simulation

    , Article Journal of Thermophysics and Heat Transfer ; Volume 20, Issue 1 , 2006 , Pages 92-100 ; 08878722 (ISSN) Mahjoob, S ; Taeibi Rahni, M ; Sharif University of Technology
    American Institute of Aeronautics and Astronautics Inc  2006
    Film cooling of surfaces appears in many applications. For instance, it is one of the most effective methods to improve the efficiency of gas turbines. As a fundamental study, two different types of film cooling (slot and discrete holes injections) are numerically simulated here. A flat surface is used to model a small portion of a gas turbine blade. Incompressible, stationary, viscous, turbulent flow is assumed using the STAR-CD software with the standard k-ε model and a cell-centered finite volume method on a nonuniform structured grid. The jet flow Reynolds number, based on the jet's hydraulic diameter, is 4.7 × 103. The study of the injection angle and the velocity ratio shows that the...