Stiffness Coefficient in the Transition Zone Between Ballasted and Ballastless Track and Its Influence on Formation Stressing

In this paper, a parametric investigation of the static and dynamic elasticity (stiffness coefficient) of the railway track and of the elastic pads of the fastenings is presented for the cases of Ballastless Track (Slab Track and Embedded Track), Transition Zone and Ballasted Track. Moreover, the influence of the variation of the static and dynamic elasticity on the acting forces on the track superstructure and substructure is investigated, a factor that is of decisive importance for the design of the Track layers and conclusions are drawn for the magnitude of the acting forces and of the mean pressure on formation in comparison to the permissible compressive stress. A methodology is also suggested for the calculation of the actions and stresses that strain the formation of the track structure

Experimental Studies in Learning Technology and Child–Computer Interaction

This book is about the ways in which experiments can be employed in the context of research on learning technologies and child–computer interaction (CCI). It is directed at researchers, supporting them to employ experimental studies while increasing their quality and rigor. The book provides a complete and comprehensive description on how to design, implement, and report experiments, with a focus on and examples from CCI and learning technology research. The topics covered include an introduction to CCI and learning technologies as interdisciplinary fields of research, how to design educational interfaces and visualizations that support experimental studies, the advantages and disadvantages of a variety of experiments, methodological decisions in designing and conducting experiments (e.g. devising hypotheses and selecting measures), and the reporting of results. As well, a brief introduction on how contemporary advances in data science, artificial intelligence, and sensor data have impacted learning technology and CCI research is presented. The book details three important issues that a learning technology and CCI researcher needs to be aware of: the importance of the context, ethical considerations, and working with children. The motivation behind and emphasis of this book is helping prospective CCI and learning technology researchers (a) to evaluate the circumstances that favor (or do not favor) the use of experiments, (b) to make the necessary methodological decisions about the type and features of the experiment, (c) to design the necessary “artifacts” (e.g., prototype systems, interfaces, materials, and procedures), (d) to operationalize and conduct experimental procedures to minimize potential bias, and (e) to report the results of their studies for successful dissemination in top-tier venues (such as journals and conferences). This book is an open access publication

Interaction Between Superstructure and Substructure in Railways

The railway track superstructure undertakes the forces that develop during train movement and distributes them towards its seating. The track panel (sleepers with their fastenings or slab with the fastenings) plays a key role in terms of load distribution, while at the same time it ensures the stability of the geometrical distance between the rails. Earthworks and ballast (if it exists) undergo residual deformations, settlements and lateral displacements, directly influencing the deterioration of the so-called geometry of the track, which can be nevertheless described much more specifically as quality of the track. In this paper, a parametric investigation of the stiffness of the substructure of the railway track and of the elastic pads of the fastenings is presented. Moreover, conclusions are drawn for the magnitude of the acting forces. A methodology is also suggested for the calculation of the actions and stresses that strain the layers of the track structure as well as for the mean pressure on the seating surface of the sleepers (or the slab) and the total settlement of the structure

Damage of Railway Sleepers under Dynamic Loads: A Case History from the Greek Railway Network

In Greece, during the 1980’s, 60% of the twin-block concrete ties designed for 200 km/h, which were laid on a track with maximum operational speed of 140 km/h, presented serious cracks. The existing theories could not justify the appearance of these cracks since the calculated actions on ties were much lower than the limit values. It was found that the geotechnical conditions of the track substructure played a key role in the damage of the sleepers. In this paper a model for the determination of the load acting on the track’s superstructure is presented properly taking into account the geotechnical conditions of the track substructure. The basic parameters of concrete tie design considering the most adverse conditions of a railway network are investigated, and a methodology for calculating the load undertaken by each tie is proposed. Finally, numerical applications on twin-block and monoblock ties are presented, including the use of high resilience fastenings. Moreover an application for the heavy-haul rail transport is presented, in case of a track equipped with W24 fastening and concrete sleepers

Frugivory and seed dispersal by carnivores in the Rhodopi mountains of northern Greece

The frugivory and seed dispersal by carnivores were studied using a combination of vegetation surveys, fruit production counts and analysis of faeces distribution and content. The study site is situated close to the Greek-Bulgarian border within a protected area. The habitat comprises of a mixed forest of beech, pine, oak and spruce which is occasionally interrupted by patches of fruiting trees. Faecal samples were collected on five permanent transects which were sampled monthly between May and October of 1993 and 1994.Fruiting plant density was found to be slightly higher in the forest than along forest roads, however the species diversity was much higher on the latter. In some cases, immature fruiting plants were found on transects with no mature plants in the vicinity. Availability of ripe fruit was found to increase steadily between May and September. There was a significant difference between the numbers of faeces deposited by the carnivores, with fox being the most numerous, followed by marten, bear and wolf. There was spatial and temporal variation in the number of faeces deposited. Nevertheless, there was no variation between different altitudinal zones. Martens were found to defecate more often on stones when compared with the other carnivores. The analysis of fruit consumption revealed that bears were the most frugivorous carnivores followed by foxes, wolves and martens on the basis of frequency of consumption. The temporal availability of each ripe fruit species coincided with their consumption by the carnivores in most of the cases. A number of seed species were deposited at altitudes where the plants do not normally grow. Foxes dispersed the highest numbers of seeds in the study area and bears were second as they deposited large-size faeces which contained many seeds. Of the dispersed seeds, those of Rubus sp., Rosa sp. and Fragaria vesca were deposited in the highest numbers. Only a small number fraction of seeds were damaged through handling by carnivores

Experimental Studies in Learning Technology and Child–Computer Interaction

This book is about the ways in which experiments can be employed in the context of research on learning technologies and child–computer interaction (CCI). It is directed at researchers, supporting them to employ experimental studies while increasing their quality and rigor. The book provides a complete and comprehensive description on how to design, implement, and report experiments, with a focus on and examples from CCI and learning technology research. The topics covered include an introduction to CCI and learning technologies as interdisciplinary fields of research, how to design educational interfaces and visualizations that support experimental studies, the advantages and disadvantages of a variety of experiments, methodological decisions in designing and conducting experiments (e.g. devising hypotheses and selecting measures), and the reporting of results. As well, a brief introduction on how contemporary advances in data science, artificial intelligence, and sensor data have impacted learning technology and CCI research is presented. The book details three important issues that a learning technology and CCI researcher needs to be aware of: the importance of the context, ethical considerations, and working with children. The motivation behind and emphasis of this book is helping prospective CCI and learning technology researchers (a) to evaluate the circumstances that favor (or do not favor) the use of experiments, (b) to make the necessary methodological decisions about the type and features of the experiment, (c) to design the necessary “artifacts” (e.g., prototype systems, interfaces, materials, and procedures), (d) to operationalize and conduct experimental procedures to minimize potential bias, and (e) to report the results of their studies for successful dissemination in top-tier venues (such as journals and conferences). This book is an open access publication

Concentração de antioxidantes nos sucos dos frutos de bananinha-do-mato e abacaxi

During February and June of 2017, in a cultivated area 10 fruits of bananinha-do-mato were 86 collected from 12 different plants and 12 pineapples were purchased from a street seller in October 87 of 2017, aiming to compare the antioxidant levels in the juice of these two bromeliads, the 88 unconventional food plant bananinha-do-mato and the famous worldwide consumed pineapple. 89 Compared with the pineapple juice, bananinha-do-mato presented significantly higher non-soluble 90 content, higher levels of the antioxidants Vitamin C and phenols, and higher total antioxidant 91 capacity, proteins and nitrites and nitrates. Vitamin E levels were similar in bananinha-do-mato and 92 pineapple juices. In conclusion, the fruit juice of bananinha-do-mato has higher antioxidant 93 capacity than the most cultivated and consumed Bromeliaceae in the world, the pineapple