This numerical research is devoted to introducing the concept of helical cone coils and comparing the performance of helical cone coils as heat exchangers to the ordinary helical coils. Helical and spiral coils are known to have better heat and mass transfer than straight tubes, which is attributed to the generation of a vortex at the helical coil. This vortex, known as the Dean Vortex, is a secondary flow superimposed on the primary flow. The Dean number, which is a dimensionless number used in describing the Dean Vortex, is a function of Reynolds Number and the square root of the curvature ratio, so varying the curvature ratio for the same coil would vary the Dean Number. Numerical investigation based on the commercial CFD software fluent is used to study the effect of changing the structural parameters (taper angle of the helical coil, pitch and the base radius of curvature changes while the height is kept constant) on the Nusselt Number, heat transfer coefficient and coil outlet temperature. Six main coils having pipe diameters of 10 and 12.5 mm and base radius of curvature of 70, 80 and 90 mm were used in the investigation. It was found that, as the taper angle increases, both Nusselt Number and the heat transfer coefficient increase, also the pitch at the various taper angles was found to have an influence on Nusselt Number and the heat transfer coefficient. A MATLAB code was built to calculate the Nusselt Number at each coil turn, then to calculate the average Nusselt number for all of the coil turns. The MATLAB code was based on empirical correlation of Manlapaz and Churchill for ordinary helical coils. The CFD simulation results were found acceptable when compared with the MATLAB results.

The considerations presented in this paper include a computer analysis of slide bearing wear prognosis using the solutions of recurrence equations complemented with the experimental data values. On the ground of the results obtained from analytical and computational numerical calculations, and taking into account the experimental parameters of bearing material and operation boundary conditions, the control problems of slide bearing wear surfaces have been presented. The obtained results allow us to see a connection between roughness, material properties, the amplitude of vibrations, the kind of the friction forces, the hardness of materials, the sliding speed in one side and the wear increments in succeeding time units of the exploitation process in other side.

Computational gait analysis constitutes a useful tool for quantitative assessment of gait disturbances, improving functional diag nosis, assessment of treatment planning, and monitoring of disease progress. There is little research on use of computational gait analysis in neurorehabilitation of post-stroke survivors, but current evidence on its clinical application supports a favorable cost-benefit ratio. The research was conducted among 50 adult people: 25 of them after ischemic stroke constituted the study group, and 25 healthy volunteers constituted the reference group. Study group members were treated for 2 weeks (10 neurorehabilitation sessions). Spatio-temporal gait parameters were assessed before and after therapy and compared using a novel fuzzy-based assessment tool, fractal dimension measurement and gait classification based on artificial neural networks. Measured results of rehabilitation (changes of gait parameters) were statistically relevant and reflected recovery. There is good evidence to extend its use to patients with various gait diseases undergoing neurorehabilitation. However, methodology for properly conducting and interpreting the proposed assessment and analysis procedures, providing validity and reliability of their results remains a key issue. More objective clinical reasoning, based on proposed novel tools, requires further research.