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An influence of track stiffness discontinuity on pantograph base vibrations and catenary–pantograph dynamic interaction

Abstract

In this article, the computational methodology of the catenary–train–track system vibration analysis is presented and used to estimate the influence of vehicle body vibrations on the pantograph–catenary dynamic interaction. This issue is rarely referred in the literature, although any perturbations appearing at the pantograph–catenary interface are of great importance for high-speed railways. Vehicle body vibrations considered in this article are induced by the passage of train through the track stiffness discontinuity, being a frequent cause of significant dynamic effects. First, the most important assumptions of the computational model are presented, including the general idea of decomposing catenary–train–track dynamic system into two main subsystems and the concept of one-way coupling between them. Then, the pantograph base vibrations calculated for two train speeds (60 m/s, 100 m/s) and two cases of track discontinuity (a sudden increase and a sudden decrease in the stiffness of track substrate) are analyzed. Two cases of the railway vehicle suspension are considered – a typical two-stage suspension and a primary suspension alone. To evaluate catenary–pantograph dynamic interaction, the dynamic uplift of the contact wire at steady arm and the pantograph contact force is computed. It is demonstrated that an efficiency of the two-stage suspension grows with the train speed; hence, such vehicle suspension effectively suppresses strong sudden shocks of vehicle body, appearing while the train passes through the track stiffness discontinuity at a high speed. In a hypothetical case when the one-stage vehicle suspension is used, the pantograph base vibrations may increase the number of contact loss events at the catenary–pantograph interface.

Open access
Mapping Indicators of Cultural Ecosystem Services: Review and Relevance to Urban Context

Abstract

Over decades human well-being has recognized from ecosystems, not only through material goods but also through nonmaterial assets namely cultural ecosystem services (CES). Regardless of increasing Ecosystem Services (ES) research over the last decade, cultural services assessment still remains neglected and is mainly limited to marketable services such as recreation and ecotourism. Obvious challenges in standardizing definitions and measurement units have brought about numerous difficulties in accounting cultural services and specific related indicators in decision-making processes. In that regard, the current review intends to create a reference list of CES categories and related measurement units with commonly used indicators. To put it another way, we analysis 80 publications to identify the most common CES indicators using in mapping various categories of CES approaches. Results prove that there are various methods can be used in assessing CES categories, whereas we found 57 indicators can be used for that and most of these indicators can be utilized in urban planning context as spatial indicators. Moreover, it is obvious that almost the same indicators can be used in evaluating most CES categories. For instance, in case of recreation and tourism indicators almost 50 % of all collected indicators can be used for mapping it, on the contrary, in case of spiritual and religious values. In conclusion, while there are various mapping methods of CES and different indicators, most of CES categories have relatively ignored by the planner and decision-makers such as education and inspirational values. Therefore, we recommend the use of the collected indicators and relevant measurement units in assessing neglected values in future research.

Open access
Mapping Kabul’s Private Urban Green Spaces Using Geographic Information System-Supervised Classification
Open access
A New Regulation for Supporting a Circular Economy in the Plastic Industry: The Case of Peru (Short Communication)

Abstract

The present study shows the regulatory proposal related to plastic by the Peruvian government and also, the previous initiatives are described so that it can be taken as a reference for the successful implementation in other countries, taking into account the regulatory and business aspects at the same time.

Open access
The Role of Customary Law in the Forest Preservation in Bali

Abstract

The endeavors to preserve the forest in Bali cannot be isolated from the existence of local wisdom. Customary law, as a decision of Hindu religious leaders in Bali, is one of the local wisdoms which has been maintained by the society. This study examined the values of local wisdom held by indigenous people and reviewed the preservation of forests from a Hindu perspective. This research was conducted in three villages in Bali, namely Tenganan Village, Manggis Sari Village, and Sangeh Village. The residents of these villages believed that forest is a sacred area which must be maintained and preserved properly.

Open access
The determinants of economic resilience in rural regions. An examination of the Portuguese case

Abstract

This paper examines the factors that contributed to the economic resilience of rural regions in Portugal following the recent crisis. Portugal has for a long time faced the issue of regionalisation. However, rural regions in Portugal are not homogenous. Rural regions in Portugal are very diverse and experience very different economic realities. This paper adds to the growing body of literature on regional resilience by focusing exclusively on rural regions. Using an adaptation of Martin’s (2012) sensitivity index as a measure of resilience and bivariate analysis this paper examines the determinants of resilience in rural regions. In terms of economic structure, the paper interestingly finds that reliance on agriculture was beneficial while innovativeness hindered resilience. As for measures of social capital, the paper presents some contradictory findings. Higher rates of crime had a negative impact on resilience, however higher political participation also had a negative impact.

Open access
The conversion of heights of the benchmarks of the detailed vertical reference network into the PL-EVRF2007-NH frame

Abstract

The paper describes the problem of conversion of heights to the European Vertical Reference Frame 2007 for Poland (PL-EVRF2007-NH). The subject of the study is height data, and especially the detailed vertical reference network. The aim of the article is to present an alternative method of conversion to the one recommended by the Polish Head Office of Geodesy and Cartography. The proposed approach is characterised by a low implementation cost while maintaining the required accuracy.

The publication is illustrated by the case of Kętrzyn district (in the north-east part of Poland). The local reference network was converted from Kronstad’60 to PL-EVRF2007-NH in 2017.

Open access
Practical dimension of urban and regional resilience concepts: a proposal of resilience strategy model

Abstract

It is not only growth and development that is of value to local, regional and central governments, but also the ability to absorb negative phenomena and the ability to continuously transform socio-economic systems. Resilience strategies thus serve as a response to the more and more frequent and intense natural, social and economic challenges. In some approaches to urban resilience, special attention is paid to activities undertaken by cities to become inclusive, integrated, robust, resourceful, reflective, redundant and flexible. In regional strategies the emphasis is on diversity, dispersion, mutuality and modularity. The aim of the paper is to synthesise selected qualities of resilient cities and regions into a new model of resilience strategy. It assumes that goals at each level of strategy are formulated according to adaptive interpretation of the resilience concept. Development of such model would enable the use of the concept by practitioners responsible for creating development strategies.

Open access
The Consequences of Non-Uniform Founding of Concrete Tank in Weak Wet Subsoil

Abstract

The article presents problem of non-uniform foundation of structures in weak wet subsoil. The problem is illustrated with the case study of two-chamber-reinforced concrete water tank constructed in 1920s of 20th century, which cracked during construction. Under part of foundation, where the peat was found, the concrete piles were introduced.

The results of five-year measurement of crack widths with crack gauges and geodesic measurements of vertical displacement of tank were presented. These results indicate that the tank is not stable and part of broken tank supported on piles is movable.

On the basis of the presented data, the general conclusions concerning the non-uniform founding of tanks are formulated.

Open access
Construction and Monitoring of Cement/Bentonite Cutoff Walls: Case Study of Karkheh Dam, Iran

Abstract

Water seepage is one of the most important features of embankment dams. To prevent and reduce seepage, it is necessary to seal the dam. Plastic concrete cutoff walls are one of the most efficient methods in waterproofing the foundation of embankment dams on permeable alluvial substrates. Sufficient resistance to loads, low permeability to maintain dam sealing, high ductility compatible with the foundation and deformation under load without cracking are the main requirements in plastic concrete cutoff walls. In this paper, the construction and implementation of the cutoff wall of Karkheh Dam, which is one the world’s largest water sealing projects, was studied. In addition, a numerical model using Seep-3D software was developed to evaluate the efficiency of the cut-off wall to decrease the seepage over the dam’s foundation. The numerical results validated by instrumentation statistics resulted from 17-years dam operation. According to the results, after the drainage of the reservoir, the cutoff wall optimally reduced the hydraulic gradient by 0.08 from 2.35 and the water leakage by 3.1 m/s from 18.3 m/s.

Open access