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Abstract

Light pollution is one of the types of environmental pollution. The sky illuminated by the excessive light emission is an inherent element of the modern world. This phenomenon has been known for over a century, but research has been carried out only for several decades. Analysis of the brightness of the sky was made for Toruń (Poland) and neighboring areas. The main aim of the study was to study the distribution of brightness of the sky over a medium-sized city. The basic research method was a direct measurement of brightness made with the SQM photometer. The conducted research was carried out throughout the calendar year on 24 measurement stations located in Toruń. Measurement stations represented various types of buildings occurring in every city. On the basis of the obtained data, a map was made showing the extent of light pollution and its intensity, as well as the spatial distribution of this phenomenon. The brightness of the sky was also examined in terms of astronomical and weather conditions. Each aspect is documented in tabular and visual form.

Abstract

The paper discusses the use of an artificial neural network to control the operation of wastewater treatment plants with activated sludge. The task of the neural network in this case is to calculate (predict) the readings of the probe measuring the concentration of nitrate nitrogen (V) in one of the biological reactor tanks. Neural networks are known for their ability to universal approximation of virtually any relationship, including the function of many variables, but the process of “training” the network requires the presentation of many sets of input data and corresponding expected results. This is a difficulty in the case of wastewater treatment plants, because some key process parameters are usually not measured online (samples are taken and measurements are taken in the laboratory), and even if they are, the time intervals are large. Bearing in mind the aforementioned difficulty, this work uses a set of input data consisting only of information that can be measured with measuring probes.

As a result of the conducted experiments a high compliance of the probe’s prediction with the expected values was obtained. The paper also presents data preparation and the network “training” process.

Abstract

Revitalisation of degraded downtown areas is a problem for many cities and towns in Europe. All spatial, economic and social changes result from the expectations of residents together with technical needs. The scope of revitalisation activities results from the diagnosis of the technical condition of the degraded part of the city. The article presents a sample assessment of the technical condition of a tenement house in Kożuchów located within a downtown complex covered by revitalisation plans.

Abstract

This paper discusses the effects of partial replacement of cement with fluidized bed bottom ash on the properties of mortars. The analyzed ash samples originating from four Polish power plants were separated by grain size selection into fine and coarse-grained fractions. This process leads to a creation of derivative samples of differing physical properties and, partially, phase compositions, as tested in XRD and TG analyses. Despite its high water demand, the obtained fine-grained fraction has the potential for application in cementbased composites as a reactive, pozzolanic additive. An acceptable activity index may be reached when the sulfate content is limited, implying benefits of combining the ash with low gypsum cements. The coarse-grained fraction is significantly less reactive, while a high silica and aluminate content is related to improved mechanical properties of the composite. It can, therefore, potentially be used as a quasi-inert additive or a substitute for sand.

Abstract

This study investigates the flexural strength of simply-supported steel–concrete composite beams under two-point loading. A total of four specimens were tested to failure for varying parameters including type of connectors (stud and channel) and number of connectors (two and four). ANSYS software was used to establish the finite element models that can simulate the flexural behaviour of the composite beam. The test results show that a beam with channel connectors performs better than a beam with stud connectors. The composite beam with two connectors between the beam and slab causes additional deflection due to slippage in the connectors, when compared to the beam with four connectors. The results from the analytical model are in good agreement with the experimental results.

Abstract

This paper examines the partial substitution of concrete components by grinded sea mussel shells collected from the coastal region of eastern Algeria. The study proposes the recycling of this waste to reduce the excessive and increasing accumulation of these shells to relieve the marine environment. The problem lies in establishing a perfect integration of the aggregates obtained from the grinded shells of sea mussels in the formulation of various types of concrete. These substitutions significantly affect the rheology of fresh cementitious materials, which is directly related to the development of strength, modulus of elasticity, and the durability of the hardened material. The objective is to partially replace the mineral sand used in the manufacture of ordinary concrete with shell sand from grinded sea mussels, with different substitution percentages of 20%, 25%, 35%, 40%, and 50% of sand volume. The results obtained indicate a marked improvement in the characteristics of fresh concrete with minimum loss in mechanical performance.

Abstract

The freeze/thaw phenomenon is of interest for the field of transport infrastructure through the degradations it produces in the structure of construction elements. The climatic specificity of Romania on the one hand and the exposure to aggressive environments of construction elements in transport on the other hand, determine the importance of studying this phenomenon, its mode of action/propagation and also prevention and maintenance to ensure the functionality of buildings in transport infrastructure.

Currently, in the Romanian regulations [*], the assurance of sustainability is done, as in most national annexes for the application of EN 206 [1] in Europe, by a descriptive approach (concrete “designed to last”) referring to (with mandatory status) a series of requirements of the concrete composition (water / cement ratio, minimum cement dosage, entrained air, freeze/thaw resistant aggregates, etc.) and to the compressive strength (concrete compressive strength class) in depending on the classification of the element in a certain exposure class “X”.

The support of this descriptive national approach was based on the analysis of a large number of results obtained in a complex experimental program carried out by Technical University of Civil Engineering Bucharest, by analyzing the results obtained by laboratory tests on “candidate” cements and cements “reference” (having a good behavior and traditional use) as well as “in situ” tests/determinations on construction elements made with both categories of cements and maintained in specific environments.

At European level, performance approaches to sustainability have made clear progress. The development of accelerated laboratory experimental methods, the establishment of performance criteria, classes of resistance to various environmental actions and the link between them and the classes of exposure to various environmental actions were the starting point for experimental research whose results will be presented in this article.

Thus, in conjunction with these modern approaches, an analysis will be presented on the experimental results obtained in research on freeze/thaw resistance to different types of cements, carried out in collaboration with the laboratory of the Reinforced Concrete Structures Department, Technical University of Civil Engineering Bucharest and proposals for classification in different classes of freeze/thaw resistance.

Abstract

The study presents an analysis of steel I-beam warping. The calculations were made for hot-rolled IPE200 hinged beams with different lengths. After determining load-bearing capacity using the GMNIA method, the beams were strengthened with bimoment restraints at each end. The changes in critical moment and load-bearing capacity were then evaluated. The study presents the manner in which the material and geometric imperfections have been determined. The GMNIA calculations were conducted using the Finite Element Method in Abaqus software. The results were then compared to results obtained with traditional methods and acquired from LT Beam software.

Abstract

The article discusses selected issues regarding the influence of cultural-historical determinants on functional-spatial development of rural areas. Ecological, economic and social processes taking place in the last decades are examined in the context of the development of local self-governments and the rise of free market economy after Poland’s socio-economic transformation. The process of intensive rural urbanization occurs especially in areas within the impact zone of big cities. It is caused by, i.a., human migration into rural areas and development of areas of business activation. The abovementioned tendencies that occur in the ecological, economic and social context have a significant impact on functional-spatial development. Expansion of housing developments and, in effect, expansion and development of necessary technical infrastructure gives rise to many problems concerning preservation of cultural heritage of the Polish countryside. The pursuit of sustainable development of rural areas is fundamental in regard to ruralist solutions as well as preservation of traditional rural architecture. Cultural-historical determinants play a considerable role in this pursuit, especially in the context of threats that stem from overurbanization of rural areas.