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High demand for part customization shifts industries toward AM technologies. Part customization in high-volume manufacturing is developed to its limits, whereas low-volume production using AM is still economically unjustified. FDM technology is quite common in low-volume AM production, but the main issue is poor printing parameter optimization which may result in insufficient final part quality. The subject of this paper is the experimental determination of the optimal parameters for the PLA polymer FDM parts, focusing on nozzle temperature and printing speed. Part geometry and mechanical properties are evaluated for the temperature range of 170–210 °C and speeds of 40, 80, and 120 mm/min. Roughness measurements for part geometrical accuracy assessment and tensile tests for mechanical property estimation have shown the clear advantage of 190 °C and 40 mm/min over the other parameter combinations. However, for higher FDM process productivity 80 mm/min speed may also be considered with 190 °C.

In the scenario of a natural or human-induced disaster, traditional communication infrastructure is often disrupted or even completely unavailable, making the employment of emergency wireless networks highly important. In this paper, we consider an industrial Supervisory Control and Data Acquisition (SCADA) system assisted by an unmanned aerial vehicle (UAV) that restores connectivity from the master terminal unit (MTU) to the remote terminal unit (RTU). The UAV also provides power supply to the ground RTU, which transmits the signal to the end-user terminal (UT) using the harvested RF energy. The MTU-UAV and UAV-RTU channels are modeled through Nakagami-m fading, while the channel between the RTU and the UT is subject to Fisher–Snedecor composite fading. According to the channels’ characterization, the expression for evaluating the overall probability of outage events is derived. The impact of the UAV’s relative position to other terminals and the amount of harvested energy on the outage performance is investigated. In addition, the results obtained based on an independent simulation method are also provided to confirm the validity of the derived analytical results. The provided analysis shows that the position of the UAV that leads to the optimal outage system performance is highly dependent on the MTU’s output power.

Minimally invasive access cavities have been proposed in the last decade to reduce tooth tissue loss during endodontic treatment and mitigate compromised fracture resistance of endodontically treated teeth. Fracture resistance of molars with different types of access cavity design may be affected by restorative materials and aging. Insufficient literature data exist on the effect of cavity design and type of restorative materials on restorative aspects such as material adaptation or photo-polymerization in restricted access cavities. This study analyses quality of polymerization, material adaptation and fracture resistance of molars with different types of access cavities restored with glass-ionomer, high-viscosity fiber-reinforced bulk-fill and nanofilled resin composite. Plastic molar teeth with truss (TREC) and traditional endodontic access cavity (TEC) were restored with nanofilled composite (Filtek Supreme), glass-ionomer Fuji IX and Filtek or fiber-reinforced everX Posterior and Filtek. Porosity was determined using microcomputer tomography and the degree of conversion of resin-based materals using micro-Raman spectroscopy. Human molars prepared and restored in the same way were used for fracture resistance testing at baseline and after thermocycling. The results demonstrate that high-viscosity fiber-reinforced composite was difficult to adapt in TREC cavity leading to greater porosity than Filtek or Fuji. TREC design did not affect composite polymerization and led to higher fracture resistance of restored molars compared to TEC but also more unrestorable fractures.

The three-point bending test is a valuable method for evaluating the mechanical properties of 3D-printed biomaterials, which can be used in various applications. The use of 3D printing in specimen preparation enables precise control over material composition and microstructure, facilitating the investigation of different printing parameters and advanced materials. The traditional approach to analyzing the mechanical properties of a material using a three-point bending test has the disadvantage that it provides only global information about the material’s behavior. This means that it does not provide detailed insight into the local strain distribution within the material. However, the 2D Digital Image Correlation (DIC) method offers additional insight, especially in terms of strain localization. DIC is an optical technique that measures full-field displacements and strains on the surface of a sample. PLA and enhanced PLA-X material were utilized to create three-point bending samples. The aim of this paper was to analyze and compare the influence of aging on the mechanical properties of PLA and enhanced PLA-X materials using three-point bending coupled with the DIC method. The results showed statistically significant differences between the PLA and PLA-X, for both the new and aged materials. The aged PLA samples had the highest average value of maximal force around 68 N, which was an increase of 8.8% compared to the new PLA samples. On the other hand, the aged PLA-X material had an increase of 7.7% in the average maximal force compared to the new PLA-X samples. When comparing the two materials, the PLA samples had higher maximal force values, 6.2% for the new samples, and 7.3% for the aged samples. The DIC results showed that both the new PLA and PLA-X samples endured higher strain values at Points 1 and 2 than the aged ones, except for the aged PLA-X sample at Point 2, where the new sample had higher strain values. However, for the first 5 min of the experiment, both materials exhibited identical behavior, after which point significant differences started to occur for both materials, as well as at Points 1 and 2. A more profound comprehension of the biomechanical characteristics of both PLA and PLA-X material is essential to enhance the knowledge for potential biomedical applications. The DIC method was found to be a powerful tool for analyzing the deformation and failure behavior of samples and for complementing the traditional approach to material testing.

Relations between creativity, dimensions of emotional experience (valence and arousal), and familiarity of content were examined in an experiment with 92 students, grouped into two sub-samples: art and non-art students. For stimulation, 40 photos were selected from the Nencki Affective Picture System, so that the values of the dimensions were systematically varied. Students were exposed to the photos and asked to rate the familiarity of their content, and then to generate a creative title for each of them. Measuring creativity was based on the coefficients, specially constructed and derived from the assessment of titles' originality. The analysis shows that valence, arousal, and familiarity might be the predictors of creativity and that unpleasant and novel content induces more creative answers. Generative processes of art-students show certain peculiarities: they are more sensitive to the external clues, especially novel and disturbing, which might be explained by the action model of creativity.

Polypropylene (PP) is a relatively new material in fused deposition modeling (FDM) technology. The main feature of this material is its ability to significantly elongate under applied load, unlike any other thermoplastic material used in FDM technology. Not much research has been conducted on this FDM material so far, hence, the subject of this paper is the investigation of printing parameters’ influence on PP tensile properties. Targeted parameters are layer height, infill density, and the orientation of raster lines, resulting in four different manufacturing regimes. To have a better insight into the experimental results, the data are analysed using ANOVA statistical method with Tukey HSD post hoc test. Obtained statistical results have proven the printing parameter’s influence on tensile results, emphasizing the influence on elastic modulus. Here, Tukey test results show the maximal number of homogeneous subsets evidencing that all printing parameters have an influence on elastic modulus values.

The aim of this study was to examine statistical parameters and determine which had the greatest influence on the final score at the European and World Championships in the period of 2020-2024. The analysis included 24 water polo matches, featuring the top 8 placed teams from the last 3 European and World Championships. From the official statistical reports of the matches, 28 statistical parameters were analyzed, which were taken from the Total Waterpolo website. Based on the descriptive statistics, flaws and analysis of the variance of water polo parameters in the game, a total of 7 variables (Total goals, Total goal efficiency, Penalty goals efficiency, Fastbrake goals, Fastbrake shots, Powerplay goals efficiency, Saved shots efficiency) were identified as significant for winning the matches at the European and World Championships 2020-2024, and 6 variables (Total goals, Total shots, Penalty shots, Penalty saved, Penalty goals, Blocked shots) were found to be significantly different between the games at the European and World Championships, while the leading parameters were the number of shots on target and saved shots. In this research, we found that the outcome of a match can be predicted and scientifically explained with 95.8% accuracy, based on the statistical parameters and their analysis.

Data on the strain and stress status of the pipe in the circumferential direction are required for various pipe manufacturing procedures (e.g., in the oil business, the process of manufacturing seamless pipes with a conical shaft). The aim of this study is to develop a procedure to determine the strain and stress behavior of Pipe Ring Tensile Specimens (PRTSs) in the hoop direction, as there are a lack of official standardized methods for testing PRTS. This paper discusses the application of the Digital Image Correlation method for testing plastic PRTSs. PRTSs are tested using a specially designed steel tool with two D blocks. A 3D-printed PRTS is placed over two D-shaped mandrels, which are fixed on a tensile tool and tensile testing machine. The strain evolution in the gage length of the specimens is captured using the three-dimensional Digital Image Correlation (3D DIC) method. To check the geometry of the cross-section of the PRTS after fracture, all the specimens are 3D scanned. For the study, six groups of PRTS are analyzed, consisting of three filling percentages (60, 90, and 100%) and two geometry types (Single and Double PRTS). The results show that the type and percentage of filling, as well as the method of printing, affect the material behavior. However, the approach with the DIC system, 3D printer, and scanner shows that they are effective instruments for mapping complete strain fields in PRTS, and thus are effective in characterizing the mechanical properties of pipes.

This paper presents new methodology for determining the actual stress–strain diagram based on analytical equations, in combination with numerical and experimental data. The first step was to use the 3D digital image correlation (DIC) to estimate true stress–strain diagram by replacing common analytical expression for contraction with measured values. Next step was to estimate the stress concentration by using a new methodology, based on recently introduced analytical expressions and numerical verification by the finite element method (FEM), to obtain actual stress–strain diagrams, as named in this paper. The essence of new methodology is to introduce stress concentration factor into the procedure of actual stress evaluation. New methodology is then applied to determine actual stress–strain diagrams for two undermatched welded joints with different rectangular cross-section and groove shapes, made of martensitic steels X10 CrMoVNb 9-1 and Armox 500T. Results indicated that new methodology is a general one, since it is not dependent on welded joint material and geometry.

Selective laser sintering (SLS) is one of the additive manufacturing technologies dedicated to the production of high-quality parts with complex geometries. Here, polyamide 12 (PA12) is a commonly used material, for manufacturing parts with sufficient mechanical and thermal properties. In SLS, many manufacturing parameters have an effect on the mechanical properties of final parts. Even the decision regarding the orientation of a part in a powder bed may have a significant effect on the mechanical properties. In this research, the influence of horizontal (H) and vertical (V) printing orientations on the ultimate tensile strength (UTS) of fabricated PA12 specimens are examined. Our research findings show that H specimens exhibit larger deformations and smaller UTS value scatter in comparison with V specimens. Also, worth pointing out is the fact that V-oriented specimens have a higher elastic modulus. One can assume that the sintering process is more effective in V specimens, due to a more uniform laser beam trajectory than in the H specimens’ case.