International Scientific Journals
of Scientific Technical Union of Mechanical Engineering "Industry 4.0"

Cable-Stayed-Bridges are an important part of today’s constructions in the traffic infrastructure. New materials and computational technology have led to the construction of longer and slender Cable-Stayed-Bridges are under the effect of dynamic loads as wind, traffic or earthquakes. Besides comfort restrictions, the vibrations of large amplitudes effects also the lifetime of the entire structure. Oscillations of Cable-Stayed-Bridges can be reduced significantly by active damping systems. In this paper is represented shortly an electro-hydraulic actuator concept for the active damping of Cable-Stayed-Bridges. This type of control is very efficient even in large bridges (up to 900 m span). Also, the tests on a large-scale bridge show the efficiency of active damping in Cable-Stayed-Bridges using electro-hydraulic actuators. The damping of deck and cables, has become crucial in the design of cable-supported structures. Because of the effectiveness of passive damping systems is limited, this new electro-hydraulic actuator concept is developed.

The definition of plane stress and strain states plays a crucial role in engineering, as recognizing these states within a structure enables the optimization of its design. This article introduces a novel hybrid wave method for analysing a circular disc geometry, with potential extensions to other geometric configurations. The method involves applying wave forces corresponding to the external loads, which then propagate through the structure and reflect back at the contours to satisfy static equilibrium conditions. The process is conceptualized in two phases while the first phase involves the application of forces where the second phase accounts for the arrival and reflection of waves at the contour boundaries. In each case, the static equilibrium at the contours is maintained by considering the reflection of the stress waves, or return waves. By incorporating these return waves and ensuring the boundary conditions are met, this approach facilitates the determination of stress at any given point within the structure.

The development of solar cell technologies is critical for advancing sustainable energy solutions. One of the significant challenges faced by solar cells is the accumulation of dust and debris on their surfaces, which can significantly reduce their efficiency. Our research work will be focused on new development composite material which are designed to repel dirt, dust, and other contaminants, ensuring that the solar cells maintain optimal performance. The optimum WO3-B composition was utilized in this research work to prepare the SiO2/WO3- B5/ZnO film sample. The composite film sample resulted the highest photocatalytic dye degradation efficiency (92%) with the SiO2/WO3- B5/ZnO/70/30) film sample after 240 min of the UVA light irradiation.

Solar energy is a cornerstone in the transition towards sustainable and renewable energy sources. Enhancing the efficiency of solar cells is critical to maximizing energy capture and utilization. One promising approach to improve solar cell performance is the application of self-cleaning coatings. This research work explores the enhancement of the energy efficiency of solar cells through the application of a SiO2/WO3-B5 self-cleaning coated film. These coatings not only help in maintaining the cleanliness of the solar cell surfaces but also contribute to better light absorption and reduced reflection losses, ultimately leading to higher energy output.

Application of different retrofitting technologies can play a significant role in reducing energy consumption of existing buildings. This research work analyses a building in Cork (Ireland) where underfloor heating system, and natural ventilation are used to maintain comfort conditions. Underfloor heating system is the main electricity consumer of this building. Different energy efficient technologies were implemented and analyzed in terms of reducing electricity consumption through an energy software. These technologies include replacing illumination with high efficiency light; replacement of electric motos with high efficiency; introducing underfloor heating time scheduling turning on and off based on predicted weather condition; installation of presence sensors to switch ON/OFF lighting. Finally, it was decided to implement underfloor heating time scheduling as energy efficient technology to be analyzed because of limited budget available and high return on investments provided by applying this method. Result analysis shows that electricity saving on bills was about 20% on monthly basis compared to previous consumption.

This research will analyse the utilization of photovoltaic plant in a fruit storage facility to produce electricity for running the refrigerators to keep cool the fruit preservation in the Storage Facility. The building has two sets of refrigerators with a power of 18.2 kW each. Firstly, the work analysis deals with the convenience of installing a Photovoltaic Plant to produce electricity for supplying the refrigerators. Secondly, implementing energy efficiency measures such as adding a new layer of insulation to the walls has been analysed. Result analysis shows that the return of investment by the installation of Photovoltaic plant is less convenient compared to that of a thermal insulation layer on the interior sites. In conclusion, it has been decided to implement only thermal insulation as energy efficiency measures to this facility where the saving is about 15% of electricity consumption per year. Given that the saving in one year is 3069kWh and the cost of electricity is 0.09 EUR/kWh, the savings in monetary value is 276 EUR /year.

Recently, Albania as a developing country is focusing on the energy efficiency in residential and industry sector. Residential sector has very high contribution energy consumption in Albania due to many construction buildings without energy efficiency standards implementation. Most of the contribute city is Tirana where energy consumption in residential sector is very high in comparison to the other cities in Albania. Our research work will be focused on analysis of the energy audit on a private residence apartment which is located in the area of Tirana. The purpose of this paper is based on the relevant standards and norms to give appropriate recommendations for the implementation of energy efficiency which would increase the energy performance of this building.

Eutectic solder alloys are widely used in the microelectronics industry. The phenomenon of creep and its mechanisms are important aspects that influence the performance of solder alloys. During the last two decades, a Pb – solder alloys is fast becoming a reality in lead free electronic products due to harmful caused as toxic material to environment and health, international legislative pressure and marketing. The replacement of Sn – Pb alloys with Sn-Ag-Cu (SAC) alloys needs reliable results for assuring the usage of this solder joints material in electronic industry. In this paper has been studied the creep behaviour of a group of alloy in the system Sn-Ag-Cu (SAC) near the eutectic point. In this research work we have used three different alloy samples which are 95, 5Sn-3, 8Ag-0,7Cu, 96, 5Sn-3, 0Ag-0,5Cu and 95, 46Sn-3, 58Ag-0,96Cu. Indentation technique has been conducted to study the creep behaviour of these three SAC alloys by determining the creep parameters at different temperatures. The temperature used was at room temperature 30oC until 100oC and the stress used was 64MPa-178MPa for the indentation diameter 1 mm and 0.5 mm. The experimental method and results of the creep parameters like activation enthalpy Q, the stress exponent n of the power law model and the parameter of the material A were briefly described in this paper. From the creep curves, constructed for alloys and considered loads, the values of creep stress exponent n were determined for the stud ied alloys.

Tires are complex objects that consist of many different parts, each with a specific formulation, and include natural or synthetic polymers, carbon black, steel, dispersed oils, dispersed oils, sulfur for the vulcanization or bonding process, organic addit ives and inorganic, and even glass fibers. Their investigation poses a difficulty in identifying them, due to their complex structure. In the Tire
Recycling Industry we encounter the problem of quality control, which is difficult due to the lack of solubil ity of rubber particles, as well as the limited technical means of these industries. The study aimed to investigate the structure and composition of recycled tires, used in artificial turf / grass as fillers.
The study focused on the development of standard investigation methods using three instrumental and analytical techniques, as well as the study of morphological changes they have undergone during the recycling process and the impact of additives on them. The aim of this scientific search is studying the structure rubber these materials are recycled, that is one of the most important issues, especially in Albani. Through FT-IR with ATR Analysis, is a analysis technique that provides information about the chemical bonding or molecular structure of materials, Differential Calorimetry DSC and Scanning Electronic microscope (SEM) equipped with the system of
dispersive of energy spectroscopy (EDS).

The purpose of this study was to investigate the structure of recycled tires which are used in artificial turf/ grass as infi ll materials. One of the most important issues, especially in Albania is proving that these materials are recycled. In this paper it is presented the FTR with ATR system methods analyses. That will provide info regarding the combining material in rubber granules, for the investigation of their structure, it was used the spectroscopy method, with vibration infrared and Fourier FTIR transformation equipped with ATR system, a method which enables analysis of samples of thick surface, without any prior preparation. The scanning of samples was done with wavelength from 4000-400 cm-1. At the same time was possible to see the changes in the micro-structure of the tires by using the Differential scanning calorimetry (DSC) analyses.

The chromium-molybdenum steel pipe P91 is widely used in the power plants construction, because they can withstand higher temperatures and operating pressures, in order to increase operating efficiency and output. This material has a complex microstructure which is extremely vulnerable to convert into Austenite form near the temperature for heat treatment. During the welding procedure should be very carefully, because otherwise the residual stress installed post welding will reach high values. A series of experimental studies was carried out, which has shown the development in the magnitude of transverse and longitudinal residual stresses and the values in both directions were determined. For but welded joints the residual stresses in the three direction were measured and the results are reported here. For measuring was used the hole drilling method through “measuring balls” or electrical strain gauge. Except the experiments the finite element method was used to determinate the value and the distribution of the residual stresses. The experimental and FEM results were compared between them and no discrepancy was found.

The aim of this research it was the installation of a discharge sea water pipeline DN 1600 of GRP (glass-reinforced plastic) material in Vlore Bay. The analysis of the sinking of the pipe string has been carried out by using CAESAR II software and considering different load cases. The calculation was carried out for static condition (sustained load) and transient condition (occasional load). In consideration were taken the allowable stress due to bending for pipe and allowable stress for joint subjected to freezing. From the calculation it was evident that the most critical effect on the GRP pipe has done by the position of Concentrated Force due to the presence of sledge (approx.. 2 tons), not disassembled from the string after moving in the position from the shore. In these cases, where the central crane has been maintained fixed or moved downward, the maximum bending stress on the pipe was 12.03 MPa. According to the verification carried out for pipe wall in the transient condition (occasional load) the stability was good and for the joint, was shown, in the worst scenario, a bending stress 158% of the allowable one. In this case it is possible to have the crack of the resin used for the freezing of the joint but not the failure of the system joint + pipe that can withstand without, failure, a stress 3 times greater than the allowable stress for pipe according to EN1796.