rss_2.0Engineering FeedSciendo RSS Feed for Engineering Feed Structural Analysis Based on a Double Interpolation Element with Arbitrary Meshing<abstract> <title style='display:none'>Abstract</title> <p>This paper presents the plate structural analysis based on the finite element method (FEM) using a double interpolation element with arbitrary meshing. This element used in this research is related to the first-order shear deformation theory (FSDT) and the double interpolation procedure. The first stage of the procedure is the same with the standard FEM for the quadrilateral element, but the averaged nodal gradients must be computed for the second stage of this interpolation. Shape functions established by the double interpolation procedure exhibit more continuous nodal gradients and higher-order polynomial contrast compared to the standard FEM when analysing the same mesh. Note that the total degrees of freedom (DOFs) do not increase in this procedure, and the trial solution and its derivatives are continuous across inter-element boundaries. Besides, with controlling distortion factors, the interior nodes of a plate domain are derived from a set of regular nodes. Four practical examples with good results and small errors are considered in this study for showing excellent efficiency for this element. Last but not least, this element allows us to implement the procedure in an existing FEM computer code as well as can be used for nonlinear analysis in the near future.</p> </abstract>ARTICLE2021-06-30T00:00:00.000+00:00Birds Strike – Impact on the Safety of Civil Aircraft Operations in Poland in 2008–2018<abstract> <title style='display:none'>Abstract</title> <p>The authors assessed the real threat to civil aircraft traffic in Poland resulting from bird strikes. It was found that in the period 2013–2018, the probability of such events increased by four times. Data for this work were downloaded from the ECCAIRS database maintained by the Civil Aviation Authority. Air traffic events have been collected for several years in this database. An assessment of the energy of bird collision with the aircraft, resulting from the bird’s mass and relative speed of movement, was also presented. Ways to minimise the risk of collision were described by introducing crew warning systems and means to scare off birds from the airport grounds. The method of testing the resistance of turbine engines to the foreign body’s absorption was also shown, as well as design methods for increasing the engine resistance to bird strikes.</p> </abstract>ARTICLE2021-06-30T00:00:00.000+00:00The Practical Feedback Stabilization for Evolution Equations in Banach Spaces<abstract> <title style='display:none'>Abstract</title> <p>This paper investigates the notion of practical feedback stabilization of evolution equations satisfying some relaxed conditions in infinite-dimensional Banach spaces. Moreover, sufficient conditions are presented that guarantee practical stabilizability of uncertain systems based on Lyapunov functions. These results are applied to partial differential equations.</p> </abstract>ARTICLE2021-06-30T00:00:00.000+00:00Approximate Formulation of the Rigid Body Motions of an Elastic Rectangle Under Sliding Boundary Conditions<abstract> <title style='display:none'>Abstract</title> <p>Low-frequency analysis of in-plane motion of an elastic rectangle subject to end loadings together with sliding boundary conditions is considered. A perturbation scheme is employed to analyze the dynamic response of the elastic rectangle revealing nonhomogeneous boundary-value problems for harmonic and biharmonic equations corresponding to leading and next order expansions, respectively. The solution of the biharmonic equation obtained by the separation of variables, a consequence of sliding boundary conditions, gives an asymptotic correction to the rigid body motion of the rectangle. The derived explicit approximate formulae are tested for different kinds of end loadings together with numerical examples demonstrating the comparison against the exact solutions.</p> </abstract>ARTICLE2021-06-30T00:00:00.000+00:00Measurement and Evaluation of Functional and Operational Coefficients of Hydraulic Solenoid Valve Prototypes Used for Variable Valve Timing Control in Combustion Engines<abstract> <title style='display:none'>Abstract</title> <p>This paper describes the engineering structure and functions of a typical solenoid valve used in hydraulic mechanisms that are based on variable camshaft timing (VCT). The main operating parameters and functional utility coefficients of hydraulic solenoid valves have been defined. Tests of 10 reference and 10 prototype valves were run on a test stand for a comparative assessment of both engineering concepts based on Welch and Mann–Whitney statistical tests of the mean values of designated coefficients. The studies identified differences between both designs, and the obtained research material was used as an input to improve the performance of the engineered concept. To perform a final evaluation of the effects that arise as a result of changes introduced to some functional–operational coefficients, additional tests are required to be run on an engine testbed. The applied test methodology may then be used for control and verification tests of the valves, which can further be used in VCT technology.</p> </abstract>ARTICLE2021-06-30T00:00:00.000+00:00Comparative Study of the Parallel and Angular Electrical Gripper for Industrial Applications<abstract> <title style='display:none'>Abstract</title> <p>The aim of this paper is to study the position and power performances of an electrical lead screw-driven industrial gripper mechanism (LSDIGM). This work consists of designing and developing an electrical LSDIGM that has the potential to meet various demands in the automation industry and factories. The performances of both angular electrical gripper (AEG) and parallel electrical gripper (PEG) mechanisms were compared based on their position and power efficiency. The position efficiency of these electrical LSDIGM is computed from the position root mean square error (PRMSE) obtained from errors between the two measured positions (input incremental encoder and output linear encoder). In the experimental setup, a current sensor and a spring were employed to measure the current in the input of the system and the stiffness in the output of the system, respectively. The electrical power in the input of the electrical LSDIGM and the mechanical power in the output of the LSDIGMs were calculated using the current and the spring force, respectively. Finally, the power efficiency of these electrical LSDIGMs was examined and compared at different velocity circumstances.</p> </abstract>ARTICLE2021-06-30T00:00:00.000+00:00Experimental Evaluation of the Effects of Structural Changes on the Vibration Properties of CK35 Steel<abstract> <title style='display:none'>Abstract</title> <p>The microstructure of some components which operate in high-temperature conditions (e.g. boiler components, turbine blades used in gas power plants, jet engines and reactors) is subjected to changes in long run, which leads to a degradation in the mechanical properties of these components and consequently, reduces their lifecycle. Therefore, it is so useful to detect the changes in the microstructure of these parts during their operation, employing an easy, fast and non-destructive method to determine their remaining life. In this study, we evaluate the effects of the microstructural changes on natural frequencies and the damping coefficient of CK35 steel, employing the experimental modal test. We aim to use the method for power plant components, if it has significant effects. To do so, we applied spheroidization heat treatment on CK35 steel samples having a primary structure of ferrite-pearlite for 24 and 48 hours. Then, we carried out the experimental modal test on samples having different metallurgical structures, but with the same dimensions and weights. According to the findings, the spherical ferrite-carbide particles in the ferrite structure increase the natural frequencies and damping coefficient. These tests show that the structural changes in this type of steel result in slight changes in the values of natural frequencies; however, it significantly changes the damping frequencies.</p> </abstract>ARTICLE2021-06-30T00:00:00.000+00:00The Effects of Delays in Algerian Construction Projects: An Empirical Study<abstract> <title style='display:none'>Abstract</title> <p>This paper examines the effects of delays in the Algerian construction industry in order to identify the various critical aspects of the causes for improving the economy in the construction sector. A questionnaire survey was conducted to assess the perceptions of all players in the construction industry, which led to the identification of the most significant impacts of delays. The results show that ten main effects of delays in the construction sector are at the origin of many constraints that have a negative impact on the economy of the country. Further, the factor analysis technique was performed to categorize the identified effects into main groups, and it yielded 5 groups (factors). As an important contribution, the relationship between these groups was tested using the SMART-PLS, and a structural model has been developed. Also, a comparative study with other previous works on the most critical effect of delays in construction projects has been conducted and the results show that the main effects of delays in the construction industry are at the root of many constraints in reaching and achieving the objectives.</p> </abstract>ARTICLE2021-06-28T00:00:00.000+00:00The Evolution of Natural Gas Prices in EU Countries and their Impact on the Country’s Macroeconomic Indicators<abstract> <title style='display:none'>Abstract</title> <p>In the article, the authors characterize the current European market with natural gas, describing differences in prices for households and prices for companies from the point of view of individual components, where they focus more on taxes, levies and fees. The article further deals with the possible impact of the price of natural gas on the country’s economy, more specifically, the correlation with inflation, unemployment and interest rates. The main aim of the authors is to establish an appropriate econometric model, which describes the impact of the price of natural gas together with the unemployment rate and interest rates on the inflation of the country. The price of natural gas, of this strategic raw material, is one of the factors that can influence the processes for low-carbon technologies or more precisely, the process of EU decarbonisation and with it the associated amount of CO<sub>2</sub> emissions.</p> </abstract>ARTICLE2021-06-28T00:00:00.000+00:00Measuring Equivalent Cohesion C of the Frozen Soils by Compression Strength using Kriolab Equipment<abstract> <title style='display:none'>Abstract</title> <p>Current paper presents the results of the experimental analysis on permafrost uppermost soil samples with various physical properties (moisture, porosity) tested with varied external pressure and time. The aim of this work is to test properties of the soil samples intended for the construction of buildings, railways and objects of civil infrastructure by modeled external pressure, data visualization and analysis. Variations in the soil samples were studied by analysis of the equivalent soil cohesion (C<sub>eq</sub>) in frozen soil samples. Methods include integrated application of the laboratory experiments, methods of the statistical data analysis and 3D plotting performed by the selected LaTeX packages. Laboratory experiments were performed using KrioLab equipment ‘Sharikovy Stamp PSH-1’. The 15 series of experiments have been tested. Models of the soil strength are graphically presented and statistically analyzed showing the results of the experiment.</p> </abstract>ARTICLE2021-06-28T00:00:00.000+00:00Behavior of Glulam Beams Strengthened in bending with BFRP Fabrics<abstract> <title style='display:none'>Abstract</title> <p>The article presents results of an experimental studies on reinforcement of pine beams made from glued laminated timber with subsurface basalt fibers (BFRP). An experimental research program was presented, in which the bending strength of glued laminated timber of middle and lower quality class was increased after using BFRP basalt fabrics. Thanks to the use of BFRP reinforcement, an average load capacity increased by 47% and stiffness by 6% in comparison to non-reinforced elements. Based on the research, it was found that the use of BFRP basalt fabrics is an effective method for strengthening damaged wooden elements. Thus, it is an environmentally friendly method of improving the static work of structural elements by combining wood with other natural materials such as basalt fiber reinforced polymers.</p> </abstract>ARTICLE2021-06-28T00:00:00.000+00:00Assessment of Seismic Bearing Capacity of a Strip Footing Resting on Reinforced Earth Bed using Pseudo-Static Analysis<abstract> <title style='display:none'>Abstract</title> <p>The use of geosynthetic reinforcement to enhance the ultimate load-bearing capacity and reduce the anticipated settlement of the shallow foundation has gained sufficient attention in the geotechnical field. The improved performance of the shallow foundation is achieved by providing one or more layers of geosynthetics below the foundation. The full wraparound technique proved to be efficient for the confinement of soil mass and reduction in settlement of foundation however lacks the literature to ascertain the performances of such footing under dynamic loading. In view of the above, the present study examines the effect of geosynthetic layers having a finite length with full wraparound ends as a reinforcement layer, placed horizontally at a suitable depth below the foundation using the finite element modeling (FEM) and evaluates the ultimate load-bearing capacity of a strip footing resting on loose and dense coarse-grained earth beds under seismic loading and further compared to those of footing resting on unreinforced earth bed. Moreover, the effect of horizontal seismic acceleration coefficient (k<sub>h</sub>) on the ultimate load-bearing capacity has been investigated by varying k<sub>h</sub> from 0.1 to 0.6 at an interval of 0.1, for both reinforced and unreinforced earth bed having loose and dense soil strata. Furthermore, this study demonstrates that by adopting the new practice of using the geosynthetic reinforcement with the full wraparound ends in foundations, it is possible to support relatively heavier structures under static as well as dynamic loading without allowing large footing settlements. From the outcomes of the present study, it is noted that the ultimate load-bearing capacity of footing resting on loose and dense sand bed found to be improved by 60% and 18% for soils having friction angle of 25° and 40°, respectively compared to respective unreinforced earth beds under static condition.</p> </abstract>ARTICLE2021-06-28T00:00:00.000+00:00A Method to Reduce Air Heating Costs in Winter Period in the Królowa Luiza Mining Museum in Zabrze – Case Study<abstract> <title style='display:none'>Abstract</title> <p>The Królowa Luiza Mining Museum is one of the touristic objects of the Coal Mining Museum in Zabrze. In the study in concern, an assessment of ventilation of the facility was conducted. Following the assessment of the ventilation, the operating parameters of the fans were changed, inlets were sealed and a system of air ducts was designed and constructed. The ducts reintroduce the heated air from the facility to workings. The conducted activities aimed to decrease the amount of air has increased the temperature in the entire object by from 3 to 10°C, which translated into a profit of approximately 200 Euro a day. Before changing the heating system it was impossible to achieve a positive temperature in the entire object at an external temperature of −10°C. It was necessary to close the Museum for tourists. Trials conducted for the external temperature from −2 to −6°C have exhibited that it will be possible to achieve positive temperatures in the entire facility even in case of very low external temperatures. The costs borne for the change of the heating system may be estimated at a level of 25000 Euro. The return of the investment should occur in the first Winter period.</p> </abstract>ARTICLE2021-06-28T00:00:00.000+00:00Recent Tendencies in Waste-Based Aggregates in Concrete Production<abstract> <title style='display:none'>Abstract</title> <p>The development of construction and the growing popularity of concrete as a building material cause a continuous increase in the demand for non-renewable raw material such as aggregate. This paper aims to analyse the possibility of using various alternative aggregates for the production of concrete. In the first part of article a detailed analysis of the European aggregate production has thus been carried out and the requirements for concrete aggregates according to European Standards have been also presented. One of the goals of sustainable waste management is to reduce landfills by finding new ways to reuse and disposing waste. Therefore in the second part of article the waste-based aggregates have been analysed. Moreover, various types of alternative aggregates such as recycled and manufactured aggregates are discussed in detail. The article presents also the properties of selected alternative aggregates with a proposal of pre-treatment. Based on the presented analyses it can be concluded that each new waste that is sourced as aggregate in concrete should undergo detailed testing because of the different chemical and mechanical properties of various waste aggregates. Hence, specific research for each waste should be undertaken.</p> </abstract>ARTICLE2021-06-28T00:00:00.000+00:00Calculating the Dynamic Impedances of Foundations and their Effect on the Seismic Response of Structures: Analytical and Numerical Study<abstract> <title style='display:none'>Abstract</title> <p>This study evaluates the movement of a frame built on soft soil under seismic excitation taking into account soil-structure interaction. First, the study was evaluated using the finite element method, then, by using a substructure method which modelled the soil using springs and dampers in a linear and nonlinear study. Rheological models were determined using impedance functions, calculated using a numerical program CONAN. These dynamic impedances are shown in the displacement vector of a three-degrees-of-freedom frame, which was calculated on the basis of lateral forces distributed over the structure height using the equivalent static method. In this regard, two different calculation norms were chosen; RPA2003 and UBC97. Finally, a parametric study was carried out, based on the effects of soil densification and the foundation geometry on the response of the RC frame.</p> </abstract>ARTICLE2021-06-28T00:00:00.000+00:00Protection of Steel Structures with Paint Coatings in the Context of Environmental Pollution<abstract> <title style='display:none'>Abstract</title> <p>The article presents important problems occurring in the operation of large-size steel structures protected by paint coatings. In our atmospheric conditions, corrosion of steel structures cannot be avoided, even with the use of protective coatings. The problem of environmental pollution with corrosion products and exfoliated paint then appears. When designing corrosion protection, durability of protection is assumed based on environmental corrosivity categories, but in practice degradation of paint coatings can occur much faster. The problem of premature peeling of paint results, among other things, from its faulty application and use. Steel structure repairs are usually carried out comprehensively, and new protection requires the removal of damaged coatings, mainly by sanding. As a result of the mechanical action of the abrasive material, old paints and corrosion products are removed, which results in a very large amount of waste that settles on the adjacent area. Due to the age of paint removed, this waste often contains compounds such as lead, chromium or zinc, which pose a real threat to the natural environment around the renovated buildings. In the article, based on the observations carried out directly on the exemplary structures in renovation, the actual scope of the waste emission was determined. This is a contribution to further spectrometric studies to determine the exact area of contamination and to identify heavy metals in the waste arising from the renovation of steel structures with paint coatings.</p> </abstract>ARTICLE2021-06-28T00:00:00.000+00:00Application of Terrestrial Laser Scanning for the Inventory of Historical Buildings on the Example of Measuring the Elevations of the Buildings in the Old Market Square in Jarosław<abstract> <title style='display:none'>Abstract</title> <p>Terrestrial laser scanning (TLS) technology is increasingly used in surveying, construction and architecture. The potential of the data obtained by this method creates the possibility of its versatile application also in conservation and revitalization of monuments, archaeology or history. The use of this technology during the creation of architectural documentation of a historic building greatly facilitates the acquisition of comprehensive information about its actual condition in a fast, non-invasive and very precise manner. Thanks to digital technology, it also creates the possibility to accurately interpret the condition of an object and present its model in a virtual space. This technology provides the ability to transfer acquired image elements with high accuracy of their mapping to plans and designs prepared by architects and contractors. It is also possible to maintain high technical standards in the processes aimed at the preparation of the required graphical studies, thanks to the use of the point cloud obtained in TLS. One of the most important advantages of using this measurement method is the possibility of combining it with data from e. g. from photogrammetric tools, which gives the possibility to fill in the missing elements creating a more complete picture of the needed data. This paper presents the implementation of terrestrial laser scanning technology as a non-invasive method for the modelling of walls and buildings of the so-called “greenfield”. Revers BIM on the example of the measurement of the facades of the buildings of the old market in Jarosław. This technology allows for preparation of precise architectural documentation including: projections, sections, elevation views, 3D models or multimedia visualizations. The use of TLS for cultural heritage research also enables the preparation of fully complete documentation for conservation and restoration works aimed at maintaining the current state of monuments or even at reconstructing their damaged architectural elements.</p> </abstract>ARTICLE2021-06-28T00:00:00.000+00:00Performance Analysis Based on Experimental Data of Backpressure Steam Turbine for Cogeneration in Saturated Steam Applications<abstract> <title style='display:none'>Abstract</title> <p>This paper aims to validate the performance capabilities of a Pressure Reducing Turbine (PRT) with respect to initial predictions based on analytic calculations. The designed equipment was installed in a beverage facility, located in Brazil. The validation procedure consists of analyzing the data collected in several periods of PRT’s operation, accessed remotely via an online server. The analysis of empirical data identifies the behavior of two key variables: generated power and effective efficiency. However, the observed boundary conditions differed significantly from expected values, forcing the turbine to operate in off-design conditions. The turbine model was hence refined and used to predict the PRT’s performance in such conditions. Results showed satisfactory accuracy for both power and efficiency predictions.</p> </abstract>ARTICLE2021-06-28T00:00:00.000+00:00Key Financial Indicators by the Size of the Construction Company - Czech Study<abstract> <title style='display:none'>Abstract</title> <p>Statistical data on the values of financial indicators in individual fields in the Czech Republic are provided by the Ministry of Industry and Trade. Updated values are issued quarterly. However, within the statistical samples, there are on average 34 companies focusing on construction. Moreover, no document specifies the size of the companies. Although the scientific literature provides basic financial rules, this research has confirmed that companies of different sizes show different values of financial indicators. For this reason, one of the aims of the research described in the article was to verify the hypothesis that companies of different sizes have different approaches to financial management and the other aims was to focus on correlating data on key financial indicators of individual sizes of companies with statistics provided by the Ministry of Industry and Trade. Basic methods of financial analysis (vertical analysis), selected ratios and basic statistical methods, which include correlation analysis, were used. The analysis was performed on 30 samples of construction companies, which were divided by size into small, medium and large. The outputs of the research will be further used for the follow-up research.</p> </abstract>ARTICLE2021-06-28T00:00:00.000+00:00Maintenance Strategies, Periodic Renovations and Building Modernisation in the Aspect of the Criterion of the Whole Life Costs<abstract> <title style='display:none'>Abstract</title> <p>The article deals with the issues of building exploitation and maintenance and focuses on the characteristics of the maintenance strategies mentioned in the ISO 15686-5:2017 Buildings and constructed assets - Service life planning - Part 5: Life-cycle costing. The article describes all three strategies recommended by the ISO standard (preventive, corrective and deferred maintenance). The purpose of the article is to conduct whole life costs analysis of three variants of modernisations, renovations and maintenance strategies for a selected building. The methods of economic efficiency assessment were used, such as net present value (NPV) method and internal rate of return (IRR) method.</p> </abstract>ARTICLE2021-06-26T00:00:00.000+00:00en-us-1