ANALYSIS OF PUMPING TEST DATA WITH VARIABLE DISCHARGE IN CONFINED AQUIFERS

Οι αναλυτικές λύσεις σταθερής παροχής άντλησης χρησιμοποιούνται ευρέως για τον προσδιορισμό των υδραυλικών χαρακτηριστικών των υδροφορέων. Ωστόσο, η αντλούμενη παροχή σε φρεάτια που δεν διαθέτουν αυτορρυθμιζόμενο σύστημα ελέγχου, γενικώς μειώνεται με το χρόνο μέχρι την σταθεροποίησή της. Η αγνόηση αυτής της κατάστασης στις δοκιμαστικές αντλήσεις έχει ως συνέπεια την λανθασμένη εκτίμηση των υδρογεωλογικών παραμέτρων. Στην εργασία αυτή παρουσιάζεται μια προσεγγιστική αναλυτική λύση για τον υπολογισμό της πτώσης πιεζομετρικού φορτίου σε κλειστό υδροφορέα λόγω άντλησης με βαθμιαία μεταβαλλόμενη παροχή. Εφαρμογή της λύσης σε πραγματικά δεδομένα δοκιμαστικών αντλήσεων έδωσε πολύ ικανοποιητικά αποτελέσματα.Analytical solutions for constant-rate well pumping tests are widely used to evaluate the aquifer characteristics. However, the discharge of an uncontrolled pumping well generally decreases with time until stabilization. Ignoring this situation in pumping tests, leads to incorrect assessment of the hydrogeological parameters. This paper presents an approximate analytical solution for evaluating drawdown in confined aquifers due to gradually varied discharge. Application of the proposed solution to actual aquifer tests showed very satisfactory results

Wind Load Transfer Mechanisms on a Low Wood Building Using Full-scale Data

The wind-induced response of low-rise wood buildings has been evaluated by monitoring a specially instrumented test building exposed to real wind action. The field facilities included a state-of-the-art data acquisition system which collected wind, pressure and force data. In addition to the field monitoring, a 1:200 scaled model of the test building was tested in the wind tunnel and the envelope wind pressures were estimated for various terrain exposures. The wind-induced pressures obtained from both the full-scale and wind tunnel experiments were incorporated in the finite element model of the test building and its response was numerically derived. Vast amounts of experimental data were generated during the long-term monitoring of the test building. These data were used to successfully verify the simulation approaches in terms of both wind-induced pressures and structural forces. Some limited discrepancies were observed in the peak pressure coefficients for locations close to the roof ridge and corners. The field acquired force data revealed that the majority of the wind uplift force is supported by the two side walls. Moreover, it was experimentally verified that the wind-induced load was attenuated as it was transferred through the buildings' structural system. This attenuation was estimated to be at least 17%, as far as the total foundation uplift force is concerned, and reached the 28% for certain approaching wind directions

Wind-induced Pressures on Patio Covers

A wind tunnel study has been carried out to assess wind loads on patio covers attached to low-rise buildings. A 1:100 geometric scale building and patio cover model was constructed and tested for open exposure conditions. The patio cover model was instrumented with pressure taps on both top and bottom surfaces, allowing the simultaneous measurement of wind pressure/suction on each side of the patio cover. The effect of building/patio height was considered by testing three different model configurations. Local surface and net wind pressure and force coefficients are presented for each model configuration. Correlation analysis was carried out to demonstrate how wind flow on the top and bottom of the patio cover affects the total wind load. The findings are also compared to the limited design guidelines derived by current building codes. Finally, recommendations for design wind load standards and codes of practice are made

On the derivation of SPH schemes for shocks through inhomogeneous media

Smoothed Particle Hydrodynamics (SPH) is typically used for the simulation of shock propagation through solid media, commonly observed during hypervelocity impacts. Although schemes for impacts into monolithic structures have been studied using SPH, problems occur when multimaterial structures are considered. This study begins from a variational framework and builds schemes for multiphase compressible problems, coming from different density estimates. Algorithmic details are discussed and results are compared upon three one-dimensional Riemann problems of known behavior.</p

On the derivation of SPH schemes for shocks through inhomogeneous media

Smoothed Particle Hydrodynamics (SPH) is typically used for the simulation of shock propagation through solid media, commonly observed during hypervelocity impacts. Although schemes for impacts into monolithic structures have been studied using SPH, problems occur when multimaterial structures are considered. This study begins from a variational framework and builds schemes for multiphase compressible problems, coming from different density estimates. Algorithmic details are discussed and results are compared upon three one-dimensional Riemann problems of known behavior.</p

On the derivation of SPH schemes for shocks through inhomogeneous media

Smoothed Particle Hydrodynamics (SPH) is typically used for the simulation of shock propagation through solid media, commonly observed during hypervelocity impacts. Although schemes for impacts into monolithic structures have been studied using SPH, problems occur when multimaterial structures are considered. This study begins from a variational framework and builds schemes for multiphase compressible problems, coming from different density estimates. Algorithmic details are discussed and results are compared upon three one-dimensional Riemann problems of known behavior

Starting currents of modes in cylindrical cavities with mode-converting corrugations for second-harmonic gyrotrons

A self-consistent system of equations (known as single-mode gyrotron equations) is extended to describe the beam-wave interaction in a cylindrical gyrotron cavity with mode-converting longitudinal corrugations, which produce coupling of azimuthal basis modes. The system of equations is applied to investigate the effect of corrugations on starting currents of the cavity modes. For these modes, eigenvalues, ohmic losses, field structure, and beam-wave coupling coefficients are investigated with respect to the corrugation parameters. It is shown that properly sized mode-converting corrugations are capable of improving the selectivity properties of cylindrical cavities for second-harmonic gyrotrons

Local and Overall Wind Pressure and Force Coefficients for Solar Panels

This paper reports on an experimental study carried out to better understand the wind pressure distribution on stand-alone panel surfaces and panels attached to flat building roofs. A complex model capable to incorporate solar panels at different locations and various inclinations was constructed at a 1:200 geometric scale. Three model panels equipped with pressure taps on both surfaces (36 in total) for point and area-averaged pressure measurements were used. Pressure and force coefficients were computed for every pressure tap and for all the panels. Different configurations were tested under similar conditions in order to examine the effect of various parameters on the experimental results. A minimal gap occurred between the solar panels and the roof of the model. The study found that the net values of pressure coefficients corresponding to different configurations are affected by the panel inclination for the critical 135° wind direction, for which panels on the back location undergo higher suctions in comparison to those in the front. The effect of building height on the solar collector total load is minimal, whereas corner panels are subjected to higher net loads for critical azimuths. Simplified net pressure coefficients for the design of solar panels are provided

Cladding Pressures and Primary Structural System Forces of a Wood Building Exposed to Strong Winds.

Several studies have been carried out on the evaluation of wind-induced pressures on building envelopes. However, there is very limited research on wind-induced forces on the main structural elements of a building including its foundation. Thus, a full-scale monitoring research project was initiated to examine the wind-induced structural forces for a low-rise wood building. The field facilities include two weather stations and a test house equipped with load and pressure sensors. The house is resting on top of twenty-seven 3-axis load cells and is structurally isolated, i.e., the only points of contact between the foundation wall and the superstructure are the load cells. Simultaneously to the load monitoring, 40 pressure taps are recording the envelope pressures both on the roof and the wall surfaces. In addition to the field monitoring, a scaled model of the house was tested in a boundary layer wind tunnel using three different upstream terrain configurations that provided varying levels of turbulence characteristics suitable for comparisons with full-scale values. The analysis of the wind speed and direction field data confirmed the non-uniform variation of the basic terrain properties over the wind direction and this was also verified in the comparison of the field with the wind tunnel results. These comparisons were made in the form of both envelope pressures and total uplift forces at the foundation level and provided useful insight regarding the wind load path inside the structural elements of the building. Experimental findings were also compared to the Canadian Code and American Standard wind provisions and indicated an underestimation of the total uplift force when using the code and standard provisions in some cases