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Abstract

The article presents the current state of knowledge in the field of estimating preliminary values of storm water subcatchment calibration parameters in the case of using the Storm Water Management Model (SWMM) for building a model of storm water drainage system. The key issue is estimating the runoff width in the case of reducing the network structure and storm water catchments due to the shortening of calculation time and simplification of the model calibration process. Correction of one of the recommended literature methods has been proposed. The assessment was based on the real catchment model with single and multi-family housing. It was found possible to apply the proposed method in the case of reducing systems connected in series.

Abstract

Citizen science is a relatively new phenomenon in the Czech Republic and currently a general overview of existing citizen science projects is not available. This presents the challenge to uncover the ‘hidden’ citizen science landscapes. The main objective of this paper is to explore the (public) representation of citizen science (CS) projects and to describe their heterogeneity. The study aims to answer the question of what type of projects in the Czech Republic meet the definition of citizen science. Based on a specific methodological data-base search approach, we compiled a set of CS projects (N = 73). During the classification process, two general citizen science categories were identified. The first group (N = 46) consists of “pure” CS projects with a prevalence towards the natural sciences, principally ornithology, and thus corresponding to general European trends. Citizens usually participate in such research in the form of data collection and basic interpretation, and a high level of cooperation between academia and NGOs was detected. The second group of “potential” CS projects (N = 27) entails various forms of public participation in general, frequently coordinated by NGOs. Based on these results, we discuss the position of citizen science in the Czech Republic, including socially-oriented citizen science. Further research is strongly encouraged to achieve a more in-depth insight into this social phenomenon.

Abstract

The variety of post-socialist agricultural transitions in four different rural regions located in South Bohemia (Czech Republic), with respect to the utilisation of the older premises, is subject to analysis in this article. A complete database was constructed, containing the identification of agricultural premises in 1989 and their use in 2004 and 2017. From 1989 to 2004, a number of agricultural brownfields emerged, and many sites had been utilised for non-agricultural purposes. After 2004, the acreage of agricultural brownfields was reduced and new land-use utilisation for housing and, especially other non-agricultural activities, significantly increased. The transition in the utilisation of pre-1989 agricultural premises is strongly influenced by the social and economic contexts in which particular sites are located. Proximity to an upper-level regional centre is of crucial importance for decisions with respect to how (and if) the site will be reused. The peripheral location of the site also affects the level and the selection of options for the ways in which particular pre-1989 agricultural premises are used. In the case studies reported here, the marginality of particular regions is increased by their location in the border regions of outer peripheries, where the probability of the presence of agricultural brownfields and the probability of long-term abandonment of agricultural premises is higher. For the traditional developed countryside, we found a typical low level of the share of long-term agricultural brownfields. After 2004, the re-use of pre-1989 agricultural brownfields for agriculture was ascertained, which is complemented by their use for housing.

Abstract

The present study was conducted to investigating interaction of three types of mixing water (tap water, briny groundwater and a mixture of their equal ratio), four levels of cement substitution with zeolite in the concrete mix design (0 %, 10 %, 20 % and 30 %), two levels of cement content (250 and 350 kg·m−3) and seven curing ages (3, 7, 28, 56, 90, 180 and 365 days) on compressive strength of concrete. In order to statistical analysis of data - a means that was not employed in the similar studies - the study was designed as a factorial experiment based on the completely randomized design with 168 treatments and three replications (totally 504 concrete specimens). The results of the analysis of variance (ANOVA) showed that neither of the two-, three- and four-way interactions of curing age with other factors were not statistically significant. This means that the gain rate of compressive strength of concrete by time was significantly similar in each possible combination of cement content, water type, and zeolite percentage. However, regarding the significant two- and three-way interactions of other studied factors, more attention should be paid to the results of these interactions than the simple effects of factors. Accordingly, based on the means comparison test (least significant difference: LSD), simultaneous use of unconventional waters with zeolite up to 20 % in the cement content 350 kg·m−3 can be recommended in terms of compressive strength of concrete.

Abstract

Currently, organic halogen compounds (halogen derivatives) are often identified in water. The paper presents the problem of the presence of these newly formed compounds during water treatment processes and their occurrence in sewage. The general indicator determining the content of these compounds in aqueous solutions is the concentration of halogen derivatives of organic compounds adsorbed on activated carbon AOX, which is converted to the concentration of chlorides. The groups of derivatives of halogenated organic compounds containing chlorine and/or bromine in a molecule were characterized, and the precursors and potential for the formation of these compounds in water were described. Moreover, technological methods to prevent and remove them were described.

Abstract

Nowadays, the utilization of locally accessible materials is a crucial stage for sustainable, economical building material on the earth’s surface. Within them, brick is one of the commonly used construction materials around Jimma town due to the availability of clayed soil. Nevertheless, brick produced by small micros unskilled enterprises rather than by traditional methods, its quantity was small, and its quality was unsatisfactory because it can easily break, and it has high water-absorbing conduct. The purpose of the investigation was to improve the properties of clayed soil properties by using laterite soil for the manufacturing of bricks for masonry units. In order to achieve this, research used non-probability sampling techniques to collect samples in Jimma area. Then, the collected samples prepared for different laboratory tests and by partially replacing literate soil by 5 %, 10 %, 15 % and 20 % on a clayed soil in order to get optimum property by different mix ratio for different laboratory tests results indicated showed that the lightweight bricks could be made from the approach of this study without any deterioration in the quality of bricks.

Additionally, the compressive strength of the blocks optimum at 15 % lateritic soil replaces in clayed soil contents. The optimum firing temperature furnace at a duration burning of brick was at 1000 °C for 5hrs. It has shown that bricks prepared of clay-laterite earth capable of high resisting capacity rather than for beauty.

Abstract

The article analyses the method of enhancing a steel beam by adding additional steel members like ribs. They are rigidly connected with both flanges in a plane parallel to the web. That plates reduces warping during in-plane bending of steel beam under lateral-torsional bucking. Different thicknesses of steel plates used as ribs and different cross-sections were taken into account. Calculations were conducted using FEM and ABAQUS CAE environment. The outcomes were compared with ones from previous studies which concerned an influence of endplates on load-bearing capacity of an I-beam.

Abstract

In ballasted track, the wheel load is transmitted to the subgrade via sleepers commonly made of impregnated wood, prestressed concrete, steel or recently developed polymer sleepers. Mentioned material types of sleepers are characterized by different elastic moduli being a key parameter in any numerical model. Hence, this paper aims to determine the elastic modulus of sleepers subjected to a laboratory four-point bending test. Traffic resembling load level of 60 kN adopted from a typical axle load distributed by the rails to the sleeper was applied in a quasistatic and cyclic loading. The samples included sleepers made of polymers complemented with wood and pre-stressed concrete. The results of this paper are based on the elastic modulus investigation. Main conclusions are focused on the sleeper’s elastic modulus under changing loading frequencies. Wood and prestressed concrete sleepers indicated mainly elastic behaviour resulting in a constant elastic modulus. However, polymer sleepers showed a loading frequency dependent elastic modulus as a result of their viscous elastic behaviour. Moreover, the conclusions of this paper involve E-modulus measurements of impregnated beech sleepers in order to describe their piece by piece elasticity variation due to their natural origin.

Abstract

Walkable access is recognised as one of the most important factors for deciding to walk instead of using other modes of transport. Distance has been less accurately taken into consideration in previous walking accessibility measures, however, as they are often based on an isotropic approach or on a fixed distance threshold. The objective of this paper is to present a method of modelling continuous walking accessibility to different amenities in a city, with an integrated network-based and distance-decay approach, applied to a case study of the city of Ljubljana, Slovenia. The approach is based on a web survey to obtain data on acceptable walking distances to different types of amenities. Several distance decay functions were analysed for each type of amenity from the cumulative frequency of responses. The best fitting functions were used to model the walking accessibility surfaces for individual amenities in the network, representing five domains (retail, services, recreation, education and transportation) and an overall walking accessibility index. Despite certain limitations and a further need to assess the validity of the methods, our distance-decay network-based approach is more accurate than the isotropic or even network-based modelling of walking distances in continuous or threshold approaches, as it enables the researcher to take into account the differences in propensities to walk to different amenities. The results can be used by city authorities and planners for implementing actions to improve walking accessibility in the most problematic areas.

Abstract

The deterioration common crossing elements increase the need for the maintenance of crossings and significantly reduce the reliability, availability and safety of railway traffic. The present paper introduces the results of experimental investigation of common crossing monitoring while its deterioration during the lifecycle of crossing. The conventional methods of common crossing condition estimation with time-based features like maximal accelerations, etc. are low appropriate as statistically significant condition indicators. The proposed multifractal analysis enables to extract the significant features from acceleration measurements. The extracted features are fused together with information about the train velocities and longitudinal position of wheels impact with the Lasso regularisation and multivariate linear regression. A ranking of feature importance is done and the redundant features are identified. The developed condition indicator has good correlation to the crossing lifetime and is simple for interpretation.