Global ETD Search
Search theses and dissertations gathered from participating repositories worldwide. Every result links back to the library that holds it. No account is needed.
Results
Showing 1 to 20 of 34 for “"pressure head"”.
-
Water Content - Pressure Head Relationships of a Porous Medium
Made available in DSpace on 2014-12-10T17:12:33Z (GMT). No. of bitstreams: 1 6801852.pdf: 3332491 bytes, checksum: 524a34dd74b57294b3296d1f1d3439ec (MD5) Previous issue date: 1967
-
The Comparison of Pressure and Suction Apparatus for Soil Water Content-Pressure Head Determinations
Made available in DSpace on 2014-12-10T17:12:26Z (GMT). No. of bitstreams: 1 6604163.pdf: 1846533 bytes, checksum: 11008eec8de508a9d5ccee668a5963de (MD5) Previous issue date: 1965
-
An effective medium approximation and Monte Carlo simulation in subsurface flow modeling
… problem in a single run to generate the expected pressure head field. The proposed effective hydraulic conductivity expression for the effective medium is of the same form as the local Gardner’s equation and is easy to use. The refined Monte Carlo simulation procedure uses analytical means to …
-
End depth and flow relationships for smooth open trapezoidal and circular channels
… the momentum equation was used. The velocity and pressure head distributions at the end depth Y$\sb{\rm e}$ were determined to obtain the corresponding velocity and pressure coefficients, (alpha $\alpha$, beta $\beta$ and K). The pressure head readings were obtained through the use of a static …
-
The effect of die geometry on extruded paste flow for continuous production of pharmaceutical tablets
… The flow of the wet extrusion is driven by the pressure head generated by the torque of the screws; the minimum pressure head is dictated by the head loss across the exit die. Since the API powder blend and ethyl acetate solvent form a highly filled suspension paste, the liquid phase tends to …
-
Design for Low Power Irrigation Systems for Small Plot Farming in Eastern India
… achieved a performance point of 13 gal/min and a pressure head of 1 bar and surpassed the efficiency of every other pump of its kind currently on the market with an efficiency of 29%. The irrigation system is being tested in the field in two pilot studies (ongoing as of this writing since February …
-
Mathematical Evaluation of Steady, Laminar Flow by the use of Continuous-Wave (CW) Doppler and Pitot Tube System
… The hypothesis was that both hematocrit and pressure head influence the amplitude of the spectrum. Experiments were designed to: a) evaluate their roles on amplitude; b) derive the associated functional relationship.</p> <p>Preliminary experiments revealed that: a) the accuracy of our Doppler …
-
Parameter estimation for unsaturated flow models
… and temporally distributed water content and pressure head measurements. The inverse problem is formulated as a weighted least-squares problem. A simple but efficient Levenberg-Marquardt algorithm is developed for its solution. Sensitivity analysis is used to determine optimal sampling …
-
An experimental analysis of an impedance pump as a model for segmentation in the intestine
… geometries with impedance changes, a net pressure head was induced. With Reynolds numbers ranging from 13-1350, the viscous and inertial effects of the fluid response created interesting pressure responses. The system was found to have a natural frequency near 1.69 Hz and exhibited …
-
The continuous refill, short-burst, hand-powered water toy
… blast. This model also takes advantage of the pressure head between the channel and the reservoir, which is from a backpack, to have the water flow passively into the channel. The user then can pressurize the channel by hand with an air bulb and blast continuously. We implemented a prototype to …
-
Some flow properties of liquid helium II
The properties of pressure-induced flow of liquid helium II have been studied by the observation of the temperature and pressure dependence of the flow in narrow channels. The channels are in the form of an annular slit between two flat glass plates. Measurements of the flow rates have been made …
-
Simulação do fenômeno de infiltração em modelos chuva-vazão
… & Ampt's infiltration parameters - wetting-front pressure head Ψf’ and hydraulic conductivity at natural saturation K sat - were estimated from soil characteristic curves (matric potential x moisture retention). These curves can be obtained through Rawls, Brakensiek and Saxton's (1982) regression …
-
Modeling the flash gate board for water storage and flood control
… water storage area is wasted and the available pressure head for power generation will be less than maximum during normal conditions. Crest control gates alleviate this problem by providing a variable spillway height. The Flash Gate Board is a passive automatic crest control gate. Its purpose is …
-
The development of a multistage centrifugal pump for use in flow chemistry
… order to drive such flows, low flow rate, high pressure pumps are used. The standard pump in use is the displacement pump. However, it tends to be expensive and produces a discontinuous flow. The goal of this investigation is to prototype a miniature multistage centrifugal pump and assess …
-
Effective properties for flow in heterogeneous porous media
… distribution of conductivity and capillary pressure head being a stochastic process, the mean behavior model defined by effective properties was derived to predict the mean behavior of heterogeneous flows. Effective parameters were evaluated numerically and were parameterized in terms of …
-
Data-Driven and Process-Based Modeling Approaches for Advancing Irrigation Water and Nitrogen Management in Humid Cropping Systems
… PAW's upper limit is set with a fixed pressure head (e.g., −330 cm or −100 cm), while flux-based definitions use a drainage threshold (qFC) derived from internal drainage behavior. These choices affect how much water the model treats as available to roots during and after drainage and, …
-
Two-Dimensional Analysis of Four Types of Water-Filled Geomembrane Tubes as Temporary Flood-Fighting Devices
… outside of the tube is modeled as hydrostatic pressure and the pressures are continuously updated as the configuration of the tube is changed. The change of the internal water pressure head (IWPH) for maintaining a constant tube area during the deformation is simulated. The simulation is …
-
Realistic modelling of leakage in water distribution pipe networks
… are mostly not fixed but vary linearly with pressure. Introducing this linear relationship into the orifice equation, results in a two-part modified orifice equation for leakage modelling with pressure head exponents of 0.5 and 1.5 respectively. Current hydraulic network solvers apply the …
-
Experimental investigation on the dynamics of inflatable dams
… experimental variables are the dam's internal pressure and the stream's flow rate or the impounded water height. The existence of upstream water is shown to completely change the dynamic characteristics of the membrane-dam, now a structure-fluid system. Two aspect ratios are considered with the …
-
Numerical modelling of transport of pollutant through soils
… from a functional relationship between capillary pressure head and moisture saturation, and can be determined from laboratory tests on simple column samples of soils. A general expression is assumed to account for the effect of velocity dependence of the hydrodynamic dispersion coefficient in the …
Page 1 of 2