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• Surface Quality of Carbide Metal After Electrical Discharge Machining

  31-38

  Ľuboslav Straka

  Patrik Kuchta

  Views:

  88

  Recently, the requirements for machining shape-complex products made of hard-to-machine materials, including carbide, have been increasing significantly. However, their machining is rather problematic. Additionally, a high-quality standard of the machined surface is generally required, not only in terms of roughness but also in terms of the geometric accuracy of the machined surface. All this while maintaining a high level of economy in the machining process. However, meeting these demanding requirements in real technical practice is not always an easy task. Moreover, in combination with modern machining processes, only a limited number of production technologies can meet this requirement. Therefore, due to the high demands placed on today's modern production and the required high standard of the machined surface, progressive EDM technology is increasingly finding its application. And it is through this progressive technology that it is possible to achieve relatively good success in carbide machining. The aim of this paper was therefore to describe in detail the results of an experimental investigation aimed at identifying the quality of the machined surface achieved in terms of the roughness parameters of the machined surface in the electrical discharge machining of selected types of carbides using a wire tool electrode.

• Analysis of Differences Between Levelling Networks in the County of Hajdú-Bihar

  84-92

  Zsolt Varga

  Csaba Kézi

  Herta Czédli

  Views:

  35

  The height determination of control and detail points is essential during the process of planning and manufacturing in the practice of civil engineering. Planning maps are drawn for the former, while the intended plan is set out on the ground during manufacturing, and after the manufacturing the completed installation is mapped. Using the same reference system in all three steps, both horizontally and vertically, is recommended even though in some cases it is unavoidable to change from one reference level to another. Regardless of the fact that both refer to the mean sea level of the Baltic Sea, this can create difficulties, since the difference between the EOMA and Bendefy networks used in Hungary shows varying values depending on the geographical location. The aim of the analysis is to determine a constant difference regarding the analysed settlements based on the common points of the networks.

• Estimation of the Potential Runoff Quality Improvement as a Result of Applied Green Infrastructure Measures in a Hungarian Town

  34-41

  Gabriella Hancz

  János Biró

  Views:

  161

  Green infrastructure measures improves the quality of surface and subsurface waters along with increasing the water balance on the town level. The aim of the study is to estimate the potential runoff quality improvement by applying stormwater BMP-s along traffic roads in the town. This is of high priority in the aquifer protection area where runoff water may infiltrate into the aquifer carrying pollutants from the surface. Estimations are applied: first we determine the surface of traffic roads, then estimate the quantity of different kinds of pollutants accumulated on the surface and thirdly we estimate the expected performance of the applied green infrastructure elements based on findings in the literature. We determine the impervious urban surface area associated with transport-related functions within the protected drinking water recharge area using GIS technic using orthophotos. We estimate the expected reduction of runoff pollution assuming that stormwater BMP-s are applied in the area. The overall goal is to make the significance of diffuse pollution more obvious and enhance drinking water protection through taking diffuse pollution into consideration.

• Evaluating the Efficiency of Polyhedral Mesh Elements in Solving the Problem of the Flow around Ship’s Rudder

  241-256

  Amjd Ibraheem

  Views:

  184

  Meshing is one of the crucial key features to the success of CFD based simulations, this study is evaluating the efficiency of polyhedral elements in solving the problem of the flow around ship rudder, using a Reynolds-averaged Navier-Stokes turbulence model (SST k-ω), and compares it to a tetrahedral based mesh, considering that polyhedral elements were neglected in the past due to difficulties in implementing them, this was solved by introducing a tool by ANSYS that converges tetrahedral elements to polyhedral element, and integrating it into FLUENT software, the model was validated by comparing it with previously validated model which used the full version of ANSYS, this study was concluded using the academic version, but still it was able to produce satisfying results in predicting the lift and the drag coefficient, the pressure around the rudder surface, the velocity and the turbulent kinetic energy, finally the mesh quality was evaluated using the orthogonal quality criteria, the results showed the supremacy of the polyhedral elements in saving time and computational resources and improving mesh quality, and keeping high level of accuracy in predicting the results.