The flow of a thin film down an inclined surface over topography is considered for the case of liquids with Sisko’ s model viscosity. For the first time lubrication theory is used to reduce the governing equations to a non-linear evolution equation for a current of a Sisko’ s model non-Newtonian fluid on an inclined plane under the action of gravity and the viscous stresses. This model is solved numerically using an efficient Full Approximation Storage (FAS) multigrid algorithm. Free surface results are plotted and carefully examined near the topography for different values of power-law index np, viscosity parameter m, the aspect ratio A and for different inclination angle  of the plane with the horizontal. Number of complications and additional physical effects are discussed that enrich real situations. It is observed that the flows into narrow trenches develop a capillary ridge just in front of the upstream edge of a trench followed by a small trough. For relatively small width trenches, the free surface is almost everywhere flat as the dimensional width of the trench is much smaller than the capillary length scale. In this region, surface tension dominates the solution and acts so as to stretch a membrane across the trench leading to smaller height deviations. The ridge originates from the topographic forcing which works to force fluid upstream immediately prior to the trench before helping to accelerate it over. The upstream forcing slows down the fluid locally and increases the layer thickness.

Therefore, in this article our studies were focused on this problem. In order to correct these errors, an independent source of information was required such as imaging from another angle, topographic map or DEM. In this paper, a method for geometric calibration of SAR images is proposed. The method uses Range-Doppler (RD) equations and to implement the method used in this article, two SAR datasets are tested with RD modelling. These datasets are acquired by ALOS PALSAR spaceborne SAR sensor. Test areas covered by these datasets range from flat plains to mountainous areas, which the first dataset located in the border between United States and Mexico and the second one is in Iran. In this method, for the image georeferencing, the appropriate Digital Elevation Model (DEM) and also exact ephemeris data of the sensor is required. In the algorithm proposed in this paper, first digital elevation model transmit to range and azimuth direction. By applying this process, errors caused by topography such as foreshortening is removed in the transferred DEM. Then, the original image is registered to transfer DEM by transformation equations. The output is a georeferenced image without geometric distortions. The advantage of the method described in this article is in eliminating the requirement for any control point as well as the need for attitude and rotational parameters of the sensor. Furthermore, two experiments with different settings are designed and conducted to comprehensively evaluate the accuracy of the SAR georeferencing with RD model. Few experiments are done in this study for various purposes. The first one is to find the best transformation equation among the three types for registering images. In the first experiment the efficacy of three types of transformation equations on georeferencing of ALOS PALSAR images were evaluated with identified check points. To evaluate the accuracy of the georeferenced images, 25 check points in different parts of the image was selected. By comparing the obtained coordinates in georeferenced image and reference points in Google Earth, the RMSE was calculated for these points. In best situation, the planimetry accuracy were 20.11m for dataset A and 19.94m for dataset B and the altimetry accuracy were 30.28m for dataset A and 30.71m for dataset B. Since the ground resolution of multi-look image was 30 meters, the planimetry accuracy achieved in this research is acceptable. The other experiment is to compare the georeferenced SAR images generated from three DEMs to demonstrate the effectiveness of DEM spatial resolution on the accuracy of georeferencing SAR images. In addition we investigated the suitability of three typical DEM datasets for SAR georeferencing in RD model. The experimental results show that the best transferred DEM was obtained from the ASTER DEM of spatial resolution comparable to that of ALOS PALSAR images.

In this paper the effects of surface topographies on earthquake ground motion is considered using direct boundary element method in time domain. The presented method is effective for modeling of surface irregularities with arbitrary shape under complex incident wave form. A real topography with particular importance in Iran, Gisha Hill, which represents a complex surface irregularity, is considered as study case and its behavior is studied under several incidences. An area of about 1400 by 1200 meters is modeled with quadrilateral serendipity boundary elements and the problem is solved for synthetic earthquake time history with various azimuths and angles of incidences. The results show that the areas nearby the top of the hill experience more excitations in some cases while more amplifications occur in the edges in other cases. The amplification pattern shows to be completely dependent on wave type, azimuth and angle of incidence..

In this paper, three-dimensional scattering of plane harmonic SH, SV, P, and Rayleigh waves by surface topographies is investigated by using a boundary element method in frequency domain. It is shown that for exact evaluation of surface ground motions in topographies all efficient parameters such as geometry of the region, mechanical properties of the surrounding geological materials (density, Poisson's ratio, and shear modulus), wave type, azimuth and angle of incidence, as well as stimulation frequency must be taken into account altogether. Furthermore, the results emphasize the need for three-dimensional modeling of irregularities. Most of the topographies in the nature are composed from the simple shape. Based on this fact, four problems are considered in order to study the effects of the shape of the topography on the surface ground motion amplification. In order to assess the accuracy and efficiency of the proposed formulations for the computation of the surface displacement field amplification, several problems are considered. The investigated problems are hemispherical canyons, elliptical-shaped canyons, hemispherical hills and rectangular cube canyons.

To enhance the understanding of the impact of obstacle buildings on pollution transportation and dispersion in the atmospheric boundary layer, it is necessary to know the atmospheric flow characteristics over terrains. Wind flow characteristics in a boundary layer over a step-shaped cliff topography model with rough and smooth surfaces were studied numerically using Computational Fluid Dynamics models (CFD).The CFD models that were used for the simulation were based on the steady-state Reynolds-Average Navier- Stoke equations (RANS) with turbulence models; standard and RNG models. The rough surface was modeled using windbreak fence, which was set on the step-shaped cliff model surface. The results of the numerical model were validated against the wind tunnel results in order to optimize the turbulence model. Numerical predictions agreed reasonably with the wind tunnel results. The results indicated that rough surface has a great influence on the turbulent flow characteristics and vortex rotating. The wind velocity for rough surface near the ground level was observed to be lower than that for the smooth surface of the step-shaped cliff model. Large flow separations were formed by the windbreak fences. Distortion of the flow at the windward corner of the step created a steep gradient of velocity and large turbulent mixing.

Due to the increasing applicant of special polymers in industries, especially in the medical and aerospace industries, it is necessary to study and investigate the production and machining of these materials. Polyether ether ketone is a heat resistant polymer that is used in the medical industry nowadays. Grinding is one of the important machining processes of this material. Using conventional lubricants and cooling liquids is not optimal in machining of PEEK, because grinded workpiece must be cleaned several steps before use. In this paper, cryogenic cooling technology, as one of the newly emerging cooling systems in the field of machining that have a very high ability, does not have a negative environmental impact, and greatly reduces need to clean machining parts, has been used for cooling of the machining zone. One of the important issues of machining output parameters is surface integrity. Surface Integrity and roughness have a high importance in the performance of the finished product and is an important parameter for investigation the machinability. Comparison of the results of using compressed air and cryogenic cooling on surface roughness and surface conditions indicate the significant effect of cryogenic cooling on the output of this study.

Introduction: Several techniques have been used to modify the surface of commercially pure titanium (CPTi) implants to improve osseointegration using lasers, sandblasts, sandblasts with acid etching, and other modalities. For implant-osseointegration, surface features like the chemical composition of a surface, topography, and surface energy are essential. The present comparative study aimed to compare the impact of Er, Cr: YSGG laser, sandblasting, and acid etching implant surface modifications on the surface topography, roughness, and element chemical composition of the Ti dental implant. Methods: Thirty CPTi dental implants were divided into three groups according to the surface modification (n=10 for each group): Group A: Sandblasting with acid etching (SLActive), group B: Sandblasting, and Group C: Er, Cr: YSGG laser surface modifications. The modified surfaces were analyzed using scanning electron microscopy (SEM), profilometer, and energy dispersive x-ray spectrometry (EDS). Results: One-way analysis of variance (ANOVA) showed that there were significant differences in the mean values of average roughness (Ra) of the three groups (P<0. 05). Tukey’s post hoc test showed that the average roughness (Ra) of laser-surface modification (group C) of the implant had the highest mean value (2. 30 µm) among the different groups, while sandblasted surface modification (group B) of the implant had the lowest mean value (1. 39 µm). The SLActive (group A) sandblast with acid etching had a mean value of 1. 63 µm. SEM analysis showed that significantly modified surface topographies and different element concentrations were found within all modified groups. Conclusion: The Er, Cr: YSGG laser irradiation increased the implant surface roughness value after implant surface modification, compared to sandblasts and sandblasts with acid etching application. The observations for the SEM-EDS analysis revealed several elements with different concentrations, which were affected by the physical–chemical characteristics of the surface modification techniques. The SEM analysis showed a significant modification in implant surface topographies of the tested groups