Search for: hydraulics
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    Application of sensitivity analysis to the development of high performance adaptive hydraulic engine mounts

    , Article Vehicle System Dynamics ; Volume 39, Issue 4 , 2003 , Pages 257-278 ; 00423114 (ISSN) Foumani, M. S ; Khajepour, A ; Durali, M ; Sharif University of Technology
    In this paper, the sensitivity analysis is applied to the development of high performance adaptive hydraulic mounts. The analysis allows us to select the most effective design parameters for tuning an adaptive mount to different road and engine conditions. It is shown that in the low frequency road excitation, the upper chamber compliance and inertia of the fluid column in the inertia track are the most influential properties in changing the dynamic stiffness of the hydraulic mount. These properties for the high frequency engine excitations are the upper compliance and the inertia of the fluid column of the decoupler. For tuning the adaptive mount to different road and engine excitation, a... 

    Oblique rectangular sharp-crested weir

    , Article Proceedings of the Institution of Civil Engineers: Water and Maritime Engineering ; Volume 156, Issue 2 , 2003 , Pages 185-191 ; 14724561 (ISSN) Borghei, S. M ; Vatannia, Z ; Ghodsian, M ; Jalili, M. R ; Sharif University of Technology
    ICE Publishing  2003
    Among discharge flowmeters, the rectangular sharp-crested weir is one of the most popular and accurate, as well as being easy to work with. Using the standard weir, with the help of the conventional weir equation and Rehbock's or a similar standard formula for the discharge coefficient (Cd), the flow can be easily calculated. In order to increase the efficiency of the weir, it can be placed obliquely to the flow, increasing the effective weir length (L) and, hence, increasing the discharge for the same water head with the same channel width (B). The results of a comprehensive set of tests for oblique weirs (1·14 ≤ L/B ≤ 2·26 or oblique angles from 29° to 64°) show that for L/B less than 1·41... 

    Effect of water-cement ratio on abrasive strength, porosity and permeability of nano-silica concrete

    , Article World Applied Sciences Journal ; Volume 17, Issue 8 , 2012 , Pages 929-933 ; 18184952 (ISSN) Shamsai, A ; Peroti, S ; Rahmani, K ; Rahemi, L ; Sharif University of Technology
    Today, due to rapid development of construction of hydraulic structures like dams, the constituent material used in concrete and its durability in these kinds of structures has gained dominant interests and importance. One of the important factors of concrete durability in these structures is its resistance against abrasion due to crash of particles carried out as hydrated crystalline particulate matter. To enhance the abrasion resistance of concrete, different methods have been offered and investigated by many research3ers/ The aim of present article is to investigate the important parameter i.e. water-cement ratio on abrasive strength, porosity and the coefficient of hydraulic conductivity... 

    Hydraulic performance of labyrinth side weirs using vanes or piles

    , Article Proceedings of the Institution of Civil Engineers: Water Management ; Volume 164, Issue 5 , 2011 , Pages 229-241 ; 17417589 (ISSN) Kabiri Samani, A ; Borghei, S. M ; Esmaili, H ; Sharif University of Technology
    In the present study, methods for improving the hydraulic performance of labyrinth side weirs in a rectangular channel are reported based on model experimentation. For this purpose different arrangements and configurations of groups of guide vane plates and piles in the side weir flow field were tested. Experiments were conducted on labyrinth side weirs of different lengths and sill heights fitted in the test section of a rectangular glass-walled channel. Depths of flow were measured in both longitudinal and crosswise directions at regular intervals and their profiles were studied. It was found that the discharge coefficient of the labyrinth side weirs under these conditions gave... 

    Designing a LQR controller for an electro-hydraulic-actuated-clutch model

    , Article Proceedings of 2016 2nd International Conference on Control Science and Systems Engineering, ICCSSE 2016, 27 July 2016 through 29 July 2016 ; 2016 , Pages 82-87 ; 9781467398725 (ISBN) Pourebrahim, M ; Selk Ghafari, A ; Pourebrahim, M ; Sharif University of Technology
    Institute of Electrical and Electronics Engineers Inc  2016
    During the past decade, Electro-Hydraulic system has performed a significant role in industrial engineering as an actuator for high performance and precision positioning applications. In this case, many control methods have been developed for an electro-hydraulic actuated clutch. In this paper a Linear Quadratic Regulators (LQR) is proposed to trajectory control of a wet clutch actuated by a hydraulic servo valve mechanism. Simulation study was performed using linearized mathematical model of the system implemented in MATLAB software. Based on the simulation results performance of the proposed controller was evaluated and discussed  

    The potential impact of Fully Ceramic Microencapsulated (FCM) fuel on thermal hydraulic performance of SMART reactor

    , Article Nuclear Engineering and Design ; Volume 339 , 2018 , Pages 39-52 ; 00295493 (ISSN) Kamalpour, S ; Salehi, A. A ; Khalafi, H ; Mataji Kojouri, N ; Jahanfarnia, G ; Sharif University of Technology
    Elsevier Ltd  2018
    One of emerging advanced fuel materials for the next generations of the nuclear reactors is Fully Ceramic Microencapsulated (FCM) fuel. FCM fuel structure is comprised of TRISO particles dispersed randomly in a SiC matrix. In the present study, the thermal hydraulic performance of a SMART reactor is investigated and the results are compared with the case that conventional UO2 fuel is loaded into the core. At the beginning of the cycle, the reactor is simulated in normal operational and transient conditions. MCNPX 2.6 stochastic code is utilised to calculate neutronic parameters. COMSOL and RELAP5 codes are used for thermal hydraulic analysis. The reactor dynamics is simulated based on... 

    On identification of nonlinear systems using volterra kernels expansion on Laguerre and wavelet function

    , Article 2010 Chinese Control and Decision Conference, CCDC 2010, 26 May 2010 through 28 May 2010, Xuzhou ; 2010 , Pages 1141-1145 ; 9781424451821 (ISBN) Moodi, H ; Bustan, D ; Sharif University of Technology
    Application of Volterra series to the modeling of static and dynamic nonlinear systems is investigated in this paper and compared to other methods. For nonlinear systems with memory, Volterra series serves as a generalization of convolution integral. To parameterize the Volterra kernels for limited dimension series, different methods are discussed. We use Laguerre functions and wavelet packets as orthonormal basis and we find the poles for the basis through a genetic algorithm search. Our test system is a hydraulic actuator with a highly nonlinear dynamics which is modeled with Volterra series. The results show that dynamic model with wavelet packets give a more accurate model with respect... 

    Discharge capacity of conventional side weirs in supercritical conditions

    , Article 4th European Congress of the International Association of Hydroenvironment engineering and Research, IAHR 2016, 27 July 2016 through 29 July 2016 ; 2016 , Pages 658-664 ; 9781138029774 (ISBN) Parvaneh, A ; Jalili Ghazizadeh, M. R ; Kabiri Samani, A ; Nekooie, M. A ; Sharif University of Technology
    CRC Press/Balkema  2016
    Side weirs are widely used for level control and flow regulation in hydraulic engineering applications such as irrigation, land drainage, and sewer systems. These hydraulic structures allow a part of the flow to spill laterally when the surface of the flow in the main channel rises above the weir crest. The supercritical flow over a side-weir is a typical case of spatially varied flow with decreasing discharge. This study is aimed at investigating the variations of specific energy along the side-weir using experimental results. Some diagrams have been presented in terms of dimensionless ratio of diverted discharge to total discharge. These diagrams which can be used in the design of side... 

    Discharge coefficient of oblique labyrinth side weir

    , Article 4th European Congress of the International Association of Hydroenvironment engineering and Research, 27 July 2016 through 29 July 2016 ; 2016 , Pages 665-670 ; 9781138029774 (ISBN) Kabiri Samani, A ; Parvaneh, A ; Nekooie, M. A ; Sharif University of Technology
    CRC Press/Balkema 
    Labyrinth side weir is one type of weirs, which can be used when the length of opening is limited. One of the advantages of labyrinth side weir is to increase the effective length of weir perpendicular to the flow and, therefore, diverting more discharge with the same flow depth and weir geometry (opening and height). Discharge coefficient should be determined to investigate the weir performance and estimate the discharge passing over the weir. In this paper, hydraulic performance of labyrinth side weir with asymmetric geometry has been experimentally studied. The change to the geometry of ordinary labyrinth side weirs causes an increase in the effectiveness of the length of weir as being... 

    Thermal-hydraulic analysis of HPLWR fuel assembly cluster

    , Article Journal of Supercritical Fluids ; Volume 77 , May , 2013 , Pages 91-99 ; 08968446 (ISSN) Tashakor, S ; Salehi, A. A ; Jahanfarnia, G ; Sharif University of Technology
    The High-Performance Light Water Reactor (HPLWR) is the European version of the Supercritical-pressure Water Cooled Reactor (SCWR). Light water reactors at supercritical pressure, being currently under design, are the new generation of nuclear reactors. The present article is a thermal-hydraulic analysis of the HPLWR fuel assembly cluster. The existing thermal hydraulic codes are not capable of analyzing and designing the HPLWR fuel assembly. It is necessary to introduce a new thermal-hydraulic code that can incorporate the parameters and specifications of the HPLWR fuel assembly. The governing equations include energy, mass and momentum equations beside thermal-hydraulic equations are... 

    Experimental study of geotextile's drainage and filteration propertis under different hydraulic gradients and confining pressures

    , Article International Journal of Civil Engineering ; Volume 9, Issue 2 , 2011 , Pages 97-102 ; 17350522 (ISSN) Pak, A ; Zahmatkesh, Z ; Sharif University of Technology
    Geotextiles are one of the most widely used synthetic materials in filtration and drainage applications. Since in real applications, geotextiles are subjected to various hydraulic gradients and confining stresses, hydraulic behavior of geotextiles under different circumstances is of great practical importance. In this study filtration and drainage properties of several nonwoven needle-punched geotextiles with different properties and unit mass per area of 200g/m2, 400g/m2, 500g/m2 and 800g/m2, under various confining stresses and hydraulic gradients, were studied using standard permittivity and transmissivity equipments. Prepared samples were subjected to hydraulic heads in the range of 10cm... 

    Application of FFTBM with signal mirroring to improve accuracy assessment of MELCOR code

    , Article Nuclear Engineering and Design ; Volume 308 , 2016 , Pages 238-251 ; 00295493 (ISSN) Saghafi, M ; Ghofrani, M. B ; D'Auria, F ; Sharif University of Technology
    Elsevier Ltd  2016
    This paper deals with the application of Fast Fourier Transform Base Method (FFTBM) with signal mirroring (FFTBM-SM) to assess accuracy of MELCOR code. This provides deeper insights into how the accuracy of MELCOR code in predictions of thermal-hydraulic parameters varies during transients. The case studied was modeling of Station Black-Out (SBO) accident in PSB-VVER integral test facility by MELCOR code. The accuracy of this thermal-hydraulic modeling was previously quantified using original FFTBM in a few number of time-intervals, based on phenomenological windows of SBO accident. Accuracy indices calculated by original FFTBM in a series of time-intervals unreasonably fluctuate when the... 

    Design method and feasibility study of fully actively controlled frames

    , Article Scientia Iranica ; Volume 11, Issue 1-2 , 2004 , Pages 50-59 ; 10263098 (ISSN) Joghataie, A ; Asbmarz, M. M ; Sharif University of Technology
    Sharif University of Technology  2004
    In this paper, results of a preliminary study on the feasibility of using an Active Tendon Control (ATC) mechanism for frame structures subject to earthquakes is presented. So far, the ATC mechanism has mainly been considered as a means for installation on structures to mitigate their response under severe loading. In this study, it is desired to evaluate the possibility of using the ATC mechanism to serve as the main means for the stability of frames against earthquakes. Hence, a methodology is presented for the integrated design of frames with ATC mechanisms, which is tested numerically. A number of five-, ten-, fifteen- and twenty-story steel frames are used for this purpose. To this end,... 

    Effects of inlet position and baffle configuration on the hydraulic performance of primary settling tanks

    , Article 2005 ASME International Mechanical Engineering Congress and Exposition, IMECE 2005, Orlando, FL, 5 November 2005 through 11 November 2005 ; Volume 261 FED , 2005 , Pages 613-618 ; 08888116 (ISSN); 0791842193 (ISBN); 9780791842195 (ISBN) Firoozabadi, B ; Tamayol, A ; Ahmadi, G ; ASME Fluids Engineering Division ; Sharif University of Technology
    Circulation regions always exist in the settling tanks. These regions reduce the tank's performance and decrease effective volume of the tank. Recirculation zones would also result in short-circuiting and high flow mixing problems. Inlet position would also have effect on these, too. Using good baffle configuration may increase performance of settling tanks. One method for comparison of different tanks with each others is to use FTC. In this paper, by using FTC the effects of inlet position and baffle configuration on the hydraulic performance of primary settling tanks are studied. The best position of baffle is also determined. Copyright © 2005 by ASME  

    Pumping effect of bubble growth and collapse in microchannels: Thermo-hydraulic modeling

    , Article Scientia Iranica ; Volume 19, Issue 3 , June , 2012 , Pages 431-436 ; 10263098 (ISSN) Sajadi, B ; Saidi, M. H ; Sharif University of Technology
    In the past two decades, microfluidic systems have become more appealing due to their wide applications in many areas, such as electronics, biotechnology, medicine, etc. Recently, the advantages of using the bubble growth phenomenon as a robust actuator in microfluidic devices have directed research interests towards the investigation of various applications. In this research, a new transient thermo-hydraulic model has been developed for bubble growth in confined volumes. The present model has been used to describe the pumping effect produced by the bubble growth and collapse phenomenon in microchannels. The results show relatively good agreement with experimental data. This study is useful... 

    Experimental study of small and medium break LOCA in the TTL-2 thermo-hydraulic test loop and its modeling with RELAP5/MOD3.2 code

    , Article Scientia Iranica ; Volume 17, Issue 6 B , NOVEMBER-DECEMBER , 2010 , Pages 492-501 ; 10263098 (ISSN) Taherzadeh, M ; Jafari, J ; Vosoughi, N ; Arabnezhad, H ; Sharif University of Technology
    Small and medium break LOCA accidents at low pressure and under low velocity conditions have been studied in the TTL-2 Thermo-hydraulic Test Loop, experimentally. TTL-2 is a thermal hydraulic test facility which is designed and constructed in NSTRI to study thermal hydraulic parameters under normal operational and accident conditions of nuclear research reactors. A nodalization has been developed for the TTL-2 and experimental results have been compared with RELAP5/MOD3.2 results. The considered accidents are a 25% and 50% cold leg break without emergency core cooling systems. Results show good agreement between experiments and RELAP5/MOD3.2 results. This research provides experimental data... 

    Investigation of a nonlinear dynamic hydraulic system model through the energy analysis approach

    , Article Journal of Mechanical Science and Technology ; Volume 23, Issue 11 , 2010 , Pages 2973-2979 ; 1738494X (ISSN) Afshari, H. H ; Ehramianpour, M ; Mohammadi, M ; Sharif University of Technology
    The dynamics of a pressure regulator valve have been studied using the through Bondgraph simulation technique. This valve consists of several elements that can transmit, transform, store, and consume hydraulic energy. The governing equations of the system have been derived from the dynamic model. In solving system equations numerically, various pressure-flow characteristics across the regulator ports and orifices have been taken into consideration. This simulation study identifies some critical parameters that have significant effects on the transient response of the system. The results have been obtained using the MATLAB-SIMULINK environment. The main advantage of the proposed methodology... 

    Two-dimensional model for lateral intake flows

    , Article Proceedings of the Institution of Civil Engineers: Water Management ; Volume 158, Issue 4 , 2005 , Pages 141-150 ; 17417589 (ISSN) Kolahdoozan, M ; Taher Shamsi, A ; Sadeghi Bagheney, M ; Mohamadian, A ; Sharif University of Technology
    ICE Publishing  2005
    This paper gives details of the refinement and application of a two-dimensional horizontal model for rivers. An explicit finite-difference algorithm was used for solving the governing differential equations, which includes the conservation of mass and momentum to predict hydrodynamic parameters. The model includes different turbulence closure models - that is, constant eddy viscosity, Prandtl simple mixing length and Smagorinsky methods. An experimental programme was designed and carried out in a laboratory flume to measure the length of eddy produced at the entrance of the intake. Model predictions have been compared with experimental results for a lateral intake. The effect of different... 

    Modeling of cohesive crack growth in partially saturated porous media; A study on the permeability of cohesive fracture

    , Article International Journal of Fracture ; Volume 167, Issue 1 , Jan , 2011 , Pages 15-31 ; 03769429 (ISSN) Barani, O. R ; Khoei, A. R ; Mofid, M ; Sharif University of Technology
    Modeling the water flow in cohesive fracture is a fundamental issue in the crack growth simulation of cracked concrete gravity dams and hydraulic fracture problems. In this paper, a mathematical model is presented for the analysis of fracture propagation in the semi-saturated porous media. The solid behavior incorporates a discrete cohesive fracture model, coupled with the flow in porous media through the fracture network. The double-nodded zero-thickness cohesive interface element is employed for the mixed mode fracture behavior in tension and contact behavior in compression. The modified crack permeability is applied in fracture propagation based on the data obtained from experimental... 

    Hydraulic behaviour of flow over an oblique weir

    , Article Journal of Hydraulic Research ; Volume 48, Issue 5 , 2010 , Pages 669-673 ; 00221686 (ISSN) Kabiri Samani, A ; Ansari, A ; Borghei, S. M ; Sharif University of Technology
    A comprehensive set of experiments was performed on weirs placed obliquely in a rectangular open channel. The main objectives were to investigate the effect of the weir angle relative to the approach flow direction on the behaviour and the hydraulic flow characteristics and to examine methods such as using upstream guide vanes and inclined aprons to increase the effective oblique weir length. Results indicate that by increasing the oblique angle, the effective length of the oblique weir increases significantly. Relationships are provided for the threshold submergence and the effective length of the oblique weir. Design recommendations are also presented for the use of guide vanes and...