Archives for Technical Sciences最新文献

The main and primary goal of the research in this paper is to analyze the actual current situation in domestic civil engineering, by determining the causes of missing deadlines and exceeding budgets of civil engineering projects. Since the results of this research also indicate the most likely problems that could arise during the construction of a project, the findings and conclusions could be used in risk assessment and drawing up dynamic plans for actual projects, which would improve the situation in domestic civil engineering and increase productivity of this important industry. 

The results obtained in this paper provide a modern approach to the problem of risk in construction, provide a realistic insight into risk factors on civil engineering projects in the Republic of Serbia and the surrounding area, and facilitate the establishment of a better correlation between theory and practice in project management and risk management.

On February 6th 2023 two major earthquakes struck southeast Turkey, M7.7 Kahramanmaras and M7.6 Elbistan, respectively. Unfortunately, due to the impact of these catastrophic events more than 50 000 casualties and 35 000 collapsed buildings have been reported since then. The aim of the study is to demonstrate preliminary site response analysis and assessment of re-liquefaction potential of sites which have been affected by the earthquakes – especially the cities of Iskenderun and Golbasi. Both site-specific areas have clear evidences of liquefaction and lateral spreading events which imply the focus of the presented paper. A series of geophysical MASW and microtremor tests have been performed in order to determine shear wave velocities up to depth of 30 m as well as the fundamental natural frequency of the soil deposits. 

Moreover, samples have been collected from sand and silt ejecta in order to evaluate some basic physical properties – grain-size curves, specific gravity and plasticity parameters. On the basis of the obtained data seismic classification of the investigated sites according to current design codes has been made and in-depth distance to relatively stiff layer has been assumed. For the sake of evaluating risk of re-liquefaction the widely-used simplified stress-based approach to triggering assessment has been adopted considering some rules of the thumb (e.g., sieve analysis and plasticity properties evaluation). Lastly, post-liquefaction reconsolidation settlement and lateral displacement have been determined in terms of future earthquakes

This research paper focuses on evaluating the log piling technique as a sustainable, cost-effective, and environmentally friendly solution for reducing soil liquefaction risks during earthquakes. Although this method has been used extensively in Japan, mainly aiming for complete soil layer penetration, its economic viability is questionable in cases requiring very deep soil improvements. The study highlights that shallow ground improvement can notably enhance the seismic behavior of the soil-improvement-structure system, as evidenced by the reduced total and penetration settlements caused by liquefaction. The paper presents a methodology for determining the optimal dimensions of the modified ground zone using both small and medium-scale 1-g shaking table tests. 

The small-scale tests involve a detailed parametric study, examining variables like improvement width, pile spacing, and the depth-to-thickness ratio of the improved layer. Medium-scale tests, on the other hand, are geared towards identifying the minimum effective pile length. This approach provides a practical guideline for engineers to implement log piling for small residential buildings. Additionally, the paper utilizes finite element method (FEM) effective stress analysis, incorporating a PLAXIS 2D-based constitutive model (PM4Sand) calibrated with laboratory undrained cyclic torsional tests. This model accounts for the changes in effective stress during seismic activities. Finally, the study correlates its numerical findings with the results from the 1-g shaking table experiments, offering a well-rounded perspective on the effectiveness of log piling in mitigating liquefaction risks during seismic events

The rim of the Sarajevo depression was exposed to a strong construction expansion, which was not followed by spatial planning documentation. This work presents models of modern geodynamic processes, which are mainly caused by technogenic effects. The characteristics of these processes mainly depend on the morphological properties of the terrain, geological structure, engineering geological and hydrogeological properties, as well as technogenic factors. The aim of this work is to clarify the specificities of modern geodynamic processes in the areas of different lithological formations, and also to show their classification and special treatment considering process’s dynamic, the development method of the moving rock mass, causes of its movement; all with the goal of preventing or reclaiming the negative effects of these processes. The key factors that affect modern geodynamic processes are: terrain morphology, lithological structure, groundwater level, rock mass structure, as well as the technogenic processes.

The construction of high-rise objects in solid rocks characterized by frequent changes in its vertical profile requires a more detailed study of lithological layers, tectonic characteristics and analysis of physical and mechanical parameters. Layers of different strength and characteristics in all elements make it possible to separate it by geological environments, in order to choose the most favorable one for the foundation of objects. As part of the construction of additional silos at the existing "Molaris" Mill complex in Kozluk near Zvornik, research was conducted at the central points of the future facilities and the immediate surroundings.

Investigation works up to a depth of 12.0 m defined all the complexity of the terrain structure in a small area. Conducted research on rock samples from exploration works and from the open terrain profile showed differences in the physical and mechanical characteristics of softer rocks susceptible to solubility in water. Separated environments show that the foundation of objects cannot be done only in one environment, given the folds of the layers in a very small area.

Landfill leachate, due to its high total pollution, and above all due to their high organic pollution, represents a significant environmental problem. This study investigated the impacts of the Tilić ada landfill on ground and surface waters. The location of the landfill Tilić ada is extremely sensitive due to the fact that it is located right next to the Drina river bed on the border with the Republic of Serbia, and especially because the source of drinking water Tilić ada is located at a distance of approx. 500 meters. 

Therefore, analyses of impact of leachate from the landfill were carried out, which indicated that the groundwater is at risk even 5 years after the landfill was closed. At the same time, water analyses from the Drina River were also carried out, which showed that the water quality was not impaired in relation to the defined water class.

By designing protection measures, the occupational safety system should provide the best possible working conditions for all employees in every economic activity, including in mining production. The analysis of occupational injuries in a certain period of time should enable the collection of data on certain etiological specificities of injuries and in this way ensure the selection of adequate preventive measures of occupational safety. Monitoring the indicators of occupational injuries within the analysis, which is presented in this paper, provides information about the change in the state of working conditions and enables the determination of the general tendency of its decreasing or increasing change.

One-factor ANOVA analysis was applied to determine the variability of the results within the established groups of selected etiological factors and to determine the impact on the observed occurrence of the number of occupational injuries in the mining company. The application of Pareto analysis to determine the most dominant causes of occupational injuries is of crucial importance for determining the direction of action of preventive actions and corrective measures in the occupational safety system.

In recent years, there has been an increasing trend of entrusting the elderly to nursing homes, thus providing a suitable space that meets their physical, psychological, social, and spiritual needs has become necessary. The nursing homes is the first and simplest solution that can be considered for such individuals. However, considering the characteristics and temperament of this group, it is necessary to define a model that can meet the elderly's spiritual and physical needs, alongside maintaining their normal life, in the home of their hopes and memories. Therefore, there is a need for a model that defines a new space in accordance with the psychological and physical conditions of the elderly and can replace previous methods in order to improve the mood of the elderly.

The design of elderly homes, and certainly the creation of suitable decoration for them, should match the global standards. The concept of an elderly village is another model that has been introduced and implemented for the elderly in the West. In this model, housing units have been designed for the elderly to live alone or with their families. Basic and necessary services for the elderly are available in proximity and neighboring the housing units. These places will have a positive impact on creating a sense of usefulness, increasing hope in life, and uplifting the mood of the elderly.

The elderly have the autonomy to use these facilities and they fulfill their needs, such as suitable spaces for exercise and recreation, socializing with peers, preserving their dignity, and creating conditions for their independence during leisure time. They also provide counseling, teach necessary techniques for the elderly’s lives and more.

The aim of this study was to examine the effect of different fertilizers on the yield and antioxidant capacity of two lettuce genotypes “Santoro RZ” and “Kiribati RZ”.

Lettuce genotypes are fertilized with organic fertilizer (Slavol) and organic-inorganic NPK fertilizer (Fitofert hemisuper plus ) during the vegetation. The analyzed parameters were root length and head weight of lettuce, total phenols, and flavonoids, as well as antioxidant capacity. Lettuce genotypes “Santoro RZ” and “Kiribati RZ” fertilized with organic fertilization showed the highest content of total phenols (358.13 ± 1.30 mg RU/100 g of fresh sample), the total content of flavonoids (114.22 ± 0.3 mg RE/100 g of fresh sample) and antioxidant capacity (neutralization of DPHH radicals 58.72 ± 1.88%).

The results revealed that the yield and antioxidant capacity of lettuce can be improved by using organic fertilizers.

In the present paper we propose a new artificial neural network model for the estimation of coal cutting resistance and excavator performance as a nonlinear relationship between the examined input (excavator movement angle in the left and right direction, slice height and thickness, coal unit weight, compressive and shear strength) and output factors (excavator effective capacity, maximum current/power/force/energy consumption, linear and areal cutting resistance). We analyze the dataset collected from three open-pit coal mines in Serbia: Field D, Tamnava Eastern Field and Tamnava Western Field (all part of the Kolubara coal basin). The model is developed using a multilayer feed-forward neural network, with a Levenberg-Marquardt learning algorithm. Results of the preformed analysis indicate satisfying statistical accuracyof the developed model (R>0.9). Additionally, we analyze the individual effects of input factors on the properties of coal cutting resistance and performance of the excavator, by invokling the multiple linear regression. As a result, we single out the statististically significant and physically possible interactions between the individual controlling factors