74 research outputs found
Flood wave propagation in steep mountain rivers
No full textMost of the recent developments concerning efficient numerical schemes to solve the shallow-water equations in view of real world flood modelling purposes concern the two-dimensional form of the equations or the one-dimensional form written for rectangular, unit-width channels. Extension of these efficient schemes to the one-dimensional cross-sectional averaged shallow-water equations is not straightforward, especially when complex natural topographies are considered. This paper presents different formulations of numerical schemes based on the HLL (Harten-Lax-van Leer) solver, and the adaptation of the topographical source term treatment when cross-sections of arbitrary shape are considered. Coupled and uncoupled formulations of the equations are considered, in combination with centred and lateralised source term treatment. These schemes are compared to a numerical solver of Lax Friedrichs type based on a staggered grid. The proposed schemes are first tested against two theoretical benchmark tests and then applied to the Brembo River, an Italian alpine river, firstly simulating a steady-state condition and secondly reproducing the 2002 flood wave propagation. © IWA Publishing 2013
Analysis of influential factors on the tensile strength of polyethylene using the factorial design
No full textExperimental results obtained by tensile test on specimens made of high-density polyethylene are
presented in this work. Specimens were tested at low temperatures at different tension speeds. Factorial
design and regression analysis were used for statistical analysis of the experimental results, more
specifically the two-factorial experiment with three levels. By applying factorial design it can be
determined which of observed factors have the greatest influence on the tensile strength of the tested specimens. The analysis of the results shows that the greatest impact on Rm has the temperature. There are also shown linear regression equations for the tensile strength parameters in the function of the effective parameters. Applying this method are reduced testing time and reduced costs required for carrying out of the experiment.Publishe
Optimization and prediction of safety coefficient for surface durability of planetary gearbox using Тaguchi design and Аrtificial Neural Network
No full textOptimization of parameters of planetary transmission by using Taguchi design was performed in this paper. Used values of safety coefficient for surface durability of internal gear of planetary gearbox were obtained by calculation. Considered parameters for optimizing are material, module and gear width. The influence of each parameter on the safety coefficient for surface durability of internal gear at 95% confidence interval was found by applying ANOVA analysis. The most influential parameter is gear module with a 74.034%, followed by the width of the gear with 16,858% and 8,874% material. Prediction of safety coefficient for surface durability of internal gear of planetary gearbox was performed by applying Artificial Neural Network (ANN)
Macroscopic modeling of urban flood by a porosity approach
No full textFloods are natural disasters that can have huge economical consequences and affect an increasing number of people throughout the world. In order to mitigate risks of flooding, it is necessary to have a good knowledge of the inundation extent and the main flow direction for an extreme event. This requires reliable numerical models that can predict the water depth and the water velocity. The presence of urban areas constitutes a challenge in the modeling of flood propagation because the street scale is an order of magnitude smaller than the scale of the undeveloped domain. To avoid expensive mesh refinement in such urban areas, a classical solution consists in adopting a simplified model in the urban areas.
This dissertation is devoted to the development of a simplified modeling approach consisting in representing an urban area as a porous medium in which the pores would be the streets and the solid matrix the buildings. The governing equations are developed following the volume averaging technique. The energy losses in the urban medium and the directional effects due to the alignment of the buildings are accounted for in the closure model by drag and dispersion terms. Numerical experiments in periodic media show that the water flows preferentially in the street direction and that wider streets oppose less resistance to the flow. Finally, the new model is validated against laboratory experiments of steady flow and dam break-like flows through an idealized urban district made of 5 × 5 blocks representing the buildings.(FSA 3) -- UCL, 201
Problems discontinuity on the first level of the school system
No full textIn this paper, the author points out the problems that arise as a consequence of the discontinuity between kindergarten and school discusses, some aspects of discontinuity with which the children often face the transition from one level of education to another and provide guidelines to overcome them
Eastern Europeans in Contemporary Literature and Culture: Imagining New Europe
No full textThis timely volume provides the first comprehensive study of the way in which contemporary writers, filmmakers and the media have represented the recent phenomenon of Eastern European migration to the UK and Western Europe following the enlargement of the EU in the 21st century, the social and political changes after the fall of communism, and the Brexit vote. Exploring the recurring figures of Eastern Europeans as a new reservoir of cheap labour, the author engages with a wide range of both mainstream and neglected authors, films and programmes, including Rose Tremain, John Lanchester, Marina Lewycka, Polly Courtney, Dubravka Ugresic, Kapka Kassabova, Kwame Kwei-Armah, It's a Free World, Gypo, Britain's Hardest Workers, The Poles are Coming and Czech Dream. Analyzing the treatment of Eastern Europeans as builders, fruit pickers, nannies and victims of sex trafficking, and ways of resisting the stereotypes, this is an important intervention into debates about Europe, migration, and post-communist transition to capitalism, as represented in multiple contemporary cultural texts
тhe influence of parents on preparing a child for school
No full text: Starting school is an important developmental step / task not only for the child but also for their parents and family in which to grow up. The accomplishment of this task expands the boundaries of family / parent and the child's functioning in social, emotional and cognitive sense. The aim of this paper is to highlight the need to educate the parents of the child going to school, which would contribute to parents with awareness and sensitivity to the nature of long-term process of entering the child's entry into school, to a child's socialization process related to school and proceeded in a favorable direction. The author emphasizes the importance of having a separate program prepares parents for the child starting school, as part of the annual program of preschools / schools that educators / teachers should realize and thus improve their educational work with one hand, while on the other hand its value will be reported in a balanced relation between child-school-family, but also to avert the potential emotional difficulties, or, the child's dysfunctional behavior. Participation of professional services and school teachers / teachers in the implementation of such programs can enhance compliance of educational values that are placed in front of the child in the family and in the school environment
Application of Taguchi methods with optimization of fibre orientation angle of laminated Al/aramid/epoxy composite cardan shaft
No full textOptimization of fibre orientation angle of the laminated Al /aramid /epoxy composite cardan
shaft using Taguchi methods was carried out in this paper. The aim of the study is to obtain values of
fibre orientation angle at which the lowest value of angle of twist of shaft is obtained. The analysis of the
fibre orientation angle of the laminated composite shaft has been carried out using ANOVA analysis. The
laminated composite shaft consists of a layer of aluminum and eight layers of aramid /epoxy composite
whose fibre orientation angle taken into consideration is -45°, 0°, 45° and 90°.
To model the cardan shaft, programmes like FEMAP and NeNASTRAN were used, and they helped
obtain angles of twist of Al /aramid /epoxy composite cardan shaft at appropriate factor levels. Predicted
value of the angle of twist deviated from the experimental one by 1.805%, whereas the value obtained by
confirmation test deviated by 1.491% from the experimental value of the angle of twist.Publishe
Steady-flow experiments in urban areas and anisotropic porosity model
No full textModelling flow through an urban area is challenging because of the significant difference between the scale of individual streets and the whole district scale. This paper presents idealized experiments where buildings are represented by square blocks. The experiments were designed to highlight the effect of the street width and orientation to the main flow direction. In addition, a porosity model is developed for representing the urban district as a whole without considering the detailed geometry of the streets, but accounting for the main effects on the flow. The model introduces a tensor of drag coefficients aimed at representing directional effects. The drag coefficients are calibrated and validated using the experimental results. © 2016 International Association for Hydro-Environment Engineering and Research
APPLICATION OF TAGUCHI METHOD FOR THE SELECTION OF OPTIMAL PARAMETERS OF PLANETARY DRIVING GEAR
No full textAn experimental research is performed in this study in order to optimize the parameters of planetary driving gear. An orthogonal array and analysis of variance (ANOVA) are employed to investigate the factors: material, module and gear width on the safety coefficient for surface durability. Statistical methods of signal to noise ratio and ANOVA with 95% confidence were applied to quantify the effects of considered factors as well as to obtain the minimum value of the safety coefficient for surface durability. The results of this analysis have shown that the gear module with 80.953% has the greatest influence on the safety coefficient for surface durability of the gear. The second influential factor is a gear width with 18.392%. And the material with 0.615% has the least influence on the safety coefficient for surface durability of the gear. The regression analysis is also shown in the study.Publishe
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