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The paper examines the causality between the costs of (re)designing the organizational structure of transport companies operating in the Republic of Serbia and their competitiveness. The research was conducted on the sample of 22 transport companies, applying the Granger model of causality. The research covers the period from 2006 to 2020. The primary goal of the paper is to determine whether there is a causal relationship between the costs that companies sacrifice in (re)designing the organizational structure and their competitiveness, which is in the paper expressed by the market share. The findings indicate that there is bidirectional (or feedback) causality.

As pressure equipment is most commonly used in various industrial fields, making manufacturing processes eco-friendlier (e.g., mass reduction of the final product, material and energy savings, etc.) and transitioning to sustainable production by developing eco-innovative products will have a positive effect on the environment. The aim of this paper is to analyze globe valve housing exposed to internal pressure using full-field experimental 3D digital image correlation (3D-DIC) method and numerical strain and stress data in order to propose improvements for more sustainable development, with respect to practical engineering application of EN standards. The highest von Mises strain values around 0.03% were measured on the point of highest geometrical discontinuity, sphere/cylinder intersection. Stresses of the examined globe valve using numerical and theoretical approach are significantly below material yield limit and allowable stress for internal pressure values of 30 bar, that is significantly higher than nominal operating pressure of 6 bar, proving that structure is over-dimensioned and can be optimized. New experimental procedure development and application in full-field strain analysis contributes to increased valve housing reliability, mass reduction and material and energy savings during manufacturing which directly affects its eco-friendliness, lowers manufacturing price and increases market competitiveness.

One of the important tasks of evaluating the integrity of mechanical process elements and structures is to determine the local mechanical properties. In this paper, experimental and numerical analyses of the mechanical behavior of an output inter-heater tube, made of 12H1MF heat-resistant steel, was performed after 200,000 h of exploitation. During exploitation, the tube was exposed to various mechanisms of damage including gas corrosion. The tube was cut from a pipe system during reparations of a thermal power plant, and then cold-deformed by bending to obtain a U-bend tube, which was then used in the experiment. For this purpose, a specimen holder made of structural steel S235 was specifically designed to test such a sample. The U-bend tube was then exposed to the external compressive load during the experiment. Experimental research was based on the application of the 3D digital image correlation (DIC), while a finite element method (FEM) was applied in numerical simulation performed by using the Abaqus software package. The 3D DIC is an optical and contactless experimental method that allows measurements of displacement fields and deformations of geometrically complex structures. The Aramis system was used for the experimental analysis as well as for verification of the numerical model. During the experiment, the von Mises strain field was measured at the top of the U-bend tube, in the tightening zone, as it represents a critical place for crack initiation and propagation during the work of an inter-heater. Based on the obtained results and a comparative analysis of experimental and numerical values of the von Mises strain field at the U-bend tube, deviation of the model predictions of about 18 % was determined. The FEM predicted smaller values of the von Mises strain field compared to the DIC method. This is the result of an incomplete geometry applied in the model due to deformation that occurred in the bend zone of the U-bend tube, loss of material and the tube surface damage due to the influence of gas corrosion during 200,000 h of exploitation. Experimental analysis has confirmed that the U-bend tube, after 200,000 h of exploitation, can remain in service even if it is damaged due to the effect of gas corrosion.

Introduction/Objective. The study was conducted to identify the maximum strain generated in the samples composed of poly-methyl-methacrylate, StraumannR implants, and three types of ceramic systems. Methods. Three types of experimental models were used, loaded by external load of 100 N, 300 N, and 500 N and analyzed using the digital image correlation method. The models were composed of yttriastabilized zirconia, e.max lithium disilicate, and Vita EnamicR hybrid ceramics, placed on the StraumannR cylindrical dental implant systems (4 × 10 mm) with straight abutments. Results. Significant differences in strain values between samples with different crown material groups were detected (p = 0.000). This suggests that strain values were dependent on the type of crown material. Strain values were also affected by the region of interest (p = 0.000). Application of two-way ANOVA enabled testing of the interaction effect between two independent variables, crown material and region of interest, where a significant difference was also found (p = 0.046). This indicates that strain values were also influenced by different combinations of material type and region of interest. The highest strain values were found for Z (0.383 ± 0.015) in the apical region, and the lowest for E (0.303 ± 0.015) in the middle region. Conclusion. The study shows maximum strain in the apical and marginal directions. When considered various all-ceramics, we noticed the minimum strain below Vita EnamicsR, while the maximum strain was found in samples with yttria-stabilized zirconia crown.

Introduction/Objective. In an attempt to simplify dental procedures, a new group of resin cements, self-adhesive resin cements (SARCs), have been introduced. Performance of SARCs can widely vary. One of the main reasons of adhesion failure is polymerization shrinkage. The aim of this study was to determine, evaluate, and measure strain field of self-adhesive dual cure resin cement during polymerization in self-cure mode using 3D digital image correlation (DIC) method. Methods. The self-adhesive Maxcem Elite (Kerr, Orange, CA, USA) cement was tested in five cylindrical samples (5 mm in diameter and 2 mm in thickness) prepared by filling plastic ring-type molds. Digital images were recorded immediately after sample preparation. Results. Non-uniform strain distribution was found in resin cement with higher strain values along the periphery (up to 15%) and lower strain values in central parts (around 4%) of each sample. Conclusion. It can be concluded that DIC is a powerful tool for full-field strain measurements in material characterization. [Project of the Serbian Ministry of Education, Science and Technological Development, Grant no.TR35031 and Grant no. TR35040]

Deformations in the vicinity of dental implants are affected by their design and if threshold level of 0.3 % is surpassed, bone resorption could occur. The goal of this study is to present a novel experimental approch for the analysis of effect od dental implant geometry on the surrounding structure strain values. A bone block model, with dimensions of 68x25x9 mm, was made from polymethyl-methacrylate. 3D printed block mold also provided a fixture for vertically placed Strauman ø4.0x12 mm. The sample was loaded in a three-point bending setup. The axial force of 600 N was applied on the dental implant. The Digital Image Correlation method was used for strain and displacement measurement. The highest von Mises strain of 0.7 % is located in the area of implant neck. The maximum displacement value in loading direction was 0.466 mm. Surface strain and displacement are correlated with implant geometry. This experimental methodology can be utilized to estimate dental implant load transfer characteristics.

The primary attention in considering the fact that the percentage of hazardous chemicals consumption is inversely proportionate to the quality of ecological potential as one of the basic principles of rural development, which has direct implications for the development of agritourism, the research into the consumption of hazardous chemicals covering the period from 2011 to 2015 in the Republic of Serbia in comparison to EU 28 was conducted. The research was focused on the consumption of hazardous chemicals by divisions of Classification of activities, the consumption of hazardous chemicals by toxicity classes (A-E), and the analysis of the hazardous chemicals consumption by regions in the Republic of Serbia. The results obtained reveal the consumption of all hazardous chemicals classes per capita in Serbia is significantly lower than in the EU, and that the share of the most toxic classes is lower. Additionally, the trend of hazardous chemicals consumption is decreasing in Serbia, and stagnates in the EU. Particularly low consumption is registered in Southern and Eastern region as well as Sumadia and Western region, pointing out at the potential of these regions for development of agritourism based on this fact.

New optical stereometric methods are becoming commonplace in investigations of mechanical behaviour of biomaterials. An understanding of the mechanical behaviour of hard and soft tissues is of great importance in the design and investigation of biomaterials. The mechanical behaviour of biomaterials can be evaluated using a number of methods that are based on either contact or non-contact schemes for displacement measurement. The method for full-field measurement of strain is done by using the ARAMIS three-dimensional image correlation system. The system uses two digital cameras that provide a synchronized stereo view of the specimen and the results show the complete strain field during the tests. Several examples are presented that highlight the use of stereometric measuring system for modern biomaterials. It is shown that this measuring methodology can capture the trends of the experiments.