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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
1141

Cost Anaysis Of Sediment Removal Techniques From Reservoir

Aras, Tuce 01 May 2009 (has links) (PDF)
Siltation in reservoirs is becoming an important problem as the dams are getting older in the world. The general dam practice has been implemented in a sequence that / planning, design, construction, operation of dam until the accumulated sediment prevents its purpose function or functions. Unfortunately, effects of sedimentation and fate of the left over dams in the future are not figured. Indeed, these negative effects could be avoided, life of the reservoir can be prolonged and even the reservoir will last forever by minimizing the sedimentation. Therefore in this study, the methods that provide extension of reservoir life are discussed hydraulically, economically and applicability point of view. In addition, there is open source package program RESCON which examines and compares some sediment removal techniques economically and also hydraulically. RESCON is used in conjunction with several cases / namely &Ccedil / ubuk Dam-I, Bor&ccedil / ka Dam and Muratli Dam. Moreover, some sensitivity analyses are carried out in order to scrutiny of the program for Turkish economic conditions.
1142

Experimental Investigation On Sharp Crested Rectangular Weirs

Sisman, H. Cigdem 01 August 2009 (has links) (PDF)
Sharp crested rectangular weirs used for discharge measurement purposes in open channel hydraulics are investigated experimentally. A series of experiments were conducted by measuring discharge and head over the weir for different weir heights for full width weir. It is seen that after a certain weir height, head and discharge relation does not change. Hence a constant weir height is determined. For that height / discharge and head over the weir are measured for variable weir width, starting from the full width weir to slit weir. Description of the discharge coefficient valid for the full range of weir widths and an empirical expression involving dimensionless flow variables is aimed. Experimental data obtained for this purpose and the results of the regression analysis performed are represented.
1143

Acoustical Analysis Of Exhaust Mufflers For Earth-moving Machinery

Olgar, Tarik 01 September 2009 (has links) (PDF)
This study concerns with acoustical analysis of exhaust mufflers for earth-moving machinery. The study arises from the fact that there is a need for further noise reduction emitted by earth-moving machinery produced by Hidromek Inc. in order to be on the safe side of the limits stated in European Noise Directive 2000/14/EC. The acoustical performance of the muffler is investigated both experimental and numerical means. A three-dimensional finite element method is performed to calculate the transmission loss. An experimental setup is also developed to measure the transmission loss. Chung-Blaser, two-source and two-load methods are applied to measure the transmission loss of single expansion chamber with extended inlet/outlet. The experimental setup is verified by comparing the test results obtained by two-load method with one-dimensional analytical solution obtained by transfer matrix method. Transmission loss of the muffler of interest, calculated by finite element method is compared with the experimental results. Sound power level of earth-moving machinery and insertion loss of the muffler is measured to investigate the acoustical performance of the muffler. These results can then be served as guidance for the acoustical design of a muffler.
1144

Measurements Of Velocity Profiles By Using Particle Image Velocimeter

Kemalli, Onur 01 October 2009 (has links) (PDF)
Particle Image Velocimetry (PIV) is an optical technique used to display and evaluate the motion of fine particles in a flow. In this experimental study, velocity profiles are examined by PIV system and basic analysis methods are compared.
1145

Initiation Of Motion Of Coarse Solitary Particles On Rough Channel Beds

Kucuktepe, Omer Ilker 01 December 2009 (has links) (PDF)
In this study the incipient motion of coarse solitary particles on channel beds having different roughness heights was experimentally investigated. The experiments were conducted in a tilting flume of a rectangular cross-section having a working length of 12 m and a rough bed composed of at least 2 layers of coarse gravel of almost constant size. The roughness material of the channel bed was changed three times. The slope of the channel bed and the discharge are two main parameters that determine the initiation of motion of a given particle. The artificial particles tested in the experiments were obtained by mixing cement and iron dust at certain ratios. Dimensionless hydraulic parameters determined from theoretical analysis were related to each other. Flow depths, velocity profiles were measured and flow conditions that represent the critical conditions of initiation of motion were expressed in terms of critical velocities and shear velocities. The results were compared with the previous studies&rsquo / results.
1146

Solution Of One Dimensional Transient Flow In Composite Aquifers Using Stehfest Algorithm

Bakar, Urun 01 September 2010 (has links) (PDF)
In this study, piezometric heads in a composite aquifer composed of an alluvial deposit having a width adjacent to a semi-infinite fractured rock are determined. One dimensional transient flow induced by a constant discharge pumping rate from a stream intersecting alluvial part of the aquifer is considered. Parts of the aquifer are homogeneous andisotropic. Equations of flow, initial and boundary conditions are converted to dimensionless forms for graphical presentation and the interpretation of results independent of discharge and head inputs specific to the problem. Equations are solved first in Laplace domain and Laplace domain solutions are inverted numerically to real time domain by utilizing Stehfest algorithm.For this purpose, a set of subroutines in VBA Excel are developed. This procedure is verified by application of code to flow in semi-infinite homogeneous aquifer under constant discharge for which analytical solution is available in literature. VBA codes are also developed for two special cases of finite aquifer with impervious and with recharge boundary on the right hand side. Results of composite aquifer solutions with extreme tranmissivity values are compared with these two cases for verification of methodology and sensivity of results.
1147

Scrutinization Of Flow Characteristics Through Orifices

Yildirim, Tugce 01 September 2010 (has links) (PDF)
Orifices are essential devices for measurement and control of flow. It is important to define the flow field and understand the flow characteristics behind an orifice for the sake of reliability measures in many hydraulic engineering applications. Since analytical and experimental solutions are restricted, a numerical solution is obtained using volume of fluid (VOF) method with the CFD solver, FLUENT, for sharp crested orifices, orifice tubes and slots. The results are compared to the available data in the literature / also a large spectrum of data collection has been achieved.
1148

Utilization Of Cfd Tools In The Design Process Of A Francis Turbine

Okyay, Gizem 01 September 2010 (has links) (PDF)
Francis type turbines are commonly used in hydropower generation. Main components of the turbine are spiral case, stay vanes, guide vanes, turbine runner and the draft tube. The dimensions of these parts are dependent mainly on the design discharge, head and the speed of the rotor of the generators. In this study, a methodology is developed for parametric optimization by incorporating Matlab codes developed and commercial Computational Fluid Dynamics (CFD) codes into the design process. The design process starts with the selection of initial dimensions from experience curves, iterates to improve the overall hydraulic efficiency and obtain the detailed description of the final geometry for manufacturing with complete visualization of the computed flow field. A Francis turbine designed by the procedure developed has been manufactured and installed for energy production.
1149

Design Considerations And Performance Evaluation Of A Surge Tank For Diaphragm Pump Operation

Ozdemir, Sahika 01 September 2010 (has links) (PDF)
This thesis is performed to evaluate the design consideration and performance characteristics of a surge tank for a diaphragm pump operation and to evaluate the proper volume and inlet area of surge tank in order to reduce the pulsations of the discharge pressure. An experimental set up is constructed for a three diaphragm positive displacement pump and the experiments are conducted afterwards. The surge tanks having different volumes and the surge tank inlet area configurations are tested in order to achieve the minimum peak to peak pulsations. Experiments showed that among the different sizes of the surge tanks, the minimum peak to peak pulsations are achieved with the largest volume which is the original surge tank of the test pump used by the pump manufacturer. This result is supported by the literature which states that with greater surge tank size the magnitude of pulsations can be diminished more. Regarding the surge tank inlet area design / among the eight different adaptors a proper inlet area value is concluded having the minimum peak to peak pulsations also smaller than the original configuration.
1150

Optimal Management Of Coastal Aquifers Using Heuristic Algorithms

Demirbas, Korkut 01 April 2011 (has links) (PDF)
Excessive pumping in coastal aquifers results in seawater intrusion where optimal and efficient planning is essential. In this study, numerical solution of single potential solution by Strack is combined with genetic algorithm (GA) to find the maximum extraction amount in a coastal aquifer. Seawater intrusion is tracked with the potential value at the extraction well locations. A code is developed by combining GA and a subroutine repeatedly calling MODFLOW as a numerical solver to calculate the potential distribution for different configurations of solution (trial solutions). Potential distributions are used to evaluate the fitness values for GA. The developed model is applied to a previous work by Mantoglou. Another heuristic method, simulated annealing (SA) is utilized to compare the results of GA. Different seawater prevention methods (i.e. injection wells, canals) and decision variables related to those methods (i.e. location of the injection wells or canals) are added to model to further prevent the seawater intrusion and improve the coastal aquifer benefit. A method called &ldquo / Alternating Constraints Method&rdquo / is introduced to improve the solution for the cases with variable location. The results show that both proposed method and the regular solution with GA or SA prove to be successful methods for the optimal management of coastal aquifers.

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