Air pollution in Serbia is characterized by pronounced seasonal variability, with the heating period representing the most critical phase in terms of fine particulate matter (PM2.5). Understanding both short-term dynamics and the spatial distribution of PM2.5 in urban environments remains a key challenge. This study focuses on the assessment of PM2.5 variability in Novi Sad, combining high-resolution sensor measurements with spatial modeling perspectives. A field campaign was conducted at 21 locations across urban, industrial, mixed-use, and background environments during heating and non-heating seasons. The use of low-cost sensors enabled detailed insight into short-term fluctuations and daily patterns of PM2.5 concentrations. Wind and pollution roses were employed to explore dominant dispersion patterns and to better understand the influence of prevailing meteorological conditions on pollutant transport. To support data reliability, sensor measurements were compared with reference measurements, demonstrating a satisfactory level of agreement and confirming their suitability for further analysis and spatial interpretation. As a key outcome, high-resolution seasonal prediction maps of PM2.5 are presented as an extension of previously developed Land Use Regression (LUR) models for Novi Sad, representing the first implementation of this approach in Serbia. These maps reveal spatial distribution patterns, pollution hotspots, and potential exposure gradients across the urban area. In addition, a preliminary assessment of chronic health impacts based on PM2.5 exposure at selected monitoring locations will be discussed. Particular attention will be given to the interpretation of prediction maps and their role in understanding spatial exposure patterns in urban environments.

Airborne particulate matter, particularly PM10 represents a significant environmental and occupational health concern on construction sites. The research explores how different construction materials effects PM10 generation during handling activities. In the absence of field measurements, a simulation-based approach was applied using emission factors defined by authoritative sources, including the EMEP/EEA Guidebook and USEPA AP-42 methodology. Seven widely used materials were selected to represent diverse physical properties and usage profiles: Portland cement, gypsum board, sand, aerated concrete blocks, clay bricks, polystyrene insulation, and gravel. For each material, multiple simulations were performed under controlled assumptions, incorporating realistic background PM10 levels to replicate urban construction site conditions. A PM10 Emission Index was defined to normalize emission potential per unit mass of material handled. Results indicate that fine, low-density materials such as Portland cement and gypsum board exhibit the highest emission intensities, while coarse, dense materials such as gravel and clay bricks contribute significantly less to airborne particulate concentrations. The findings highlight the substantial variability in emission potential across materials and emphasize the importance of material selection in sustainable construction planning. These insights can guide policymakers and construction professionals in adopting low-emission materials and better on-site dust control strategies.

This research is concerned with the development of a longitudinally excited metastructure, featuring periodically distributed external units, each equipped with internal oscillators functioning as vibration absorbers. Initially, the metastructure designed for vibration attenuation around the first structural resonance, is characterized by uniformity, with all absorbers being identical and consisting of cantilevers integrated into the external components, each cantilever terminating in a concentrated mass block. This study employs a machine learning approach to maximize vibration attenuation efficiency around the second resonance, as well as concurrently at the first and second resonant frequencies in two associated optimality criteria related to the width of the attenuation region and the amplitude reduction, respectively. The new metastructures redesigned based on these criteria are fabricated by 3D printing, and their enhanced vibration mitigation capabilities are verified experimentally.

Anthropogenic activities can lead to environmental contamination and violations of the quality of the working environment, which has a negative impact on human health. Increasing construction works create noise that can have a harmful effect on human health. Standard methods for measuring noise are generally accepted, but due to certain limitations, there is a need for the development of new alternative methods, such as sensor technologies. This study compares laboratory and field measurements with the sensor device (NoiSens), and based on the results of the independent t-test, it can be concluded that there is no significant difference (t=-1.747, p=0.081) in the measured noise level. The NoiSens device proved to be reliable and efficient for measuring noise levels at construction sites, demonstrating that it can replace standard methods for noise measurement.

In inductive power transfer (IPT) systems, the relative position between the primary and secondary side assemblies affects the self-inductance of the coils and their mutual inductance. In addition, the aging effect of capacitors influences the value of compensation capacitors. It is, therefore, necessary to determine a minimum set of key IPT system parameters when implementing a constant-current (CC)/constant-voltage (CV) battery charging algorithm without real-time communication. This article presents a method for implementing the CC/CV battery charging algorithm in an LCC-S IPT system without requiring real-time communication or all system parameters. Using only measurements from the primary side, the method is based on the phasor estimation of the primary-side electromotive force (EMF). Estimated parameters include the mutual inductance, the primary-side coil self-inductance and its parasitic resistance, and the secondary-side circuit resonant frequency. The first three parameters are estimated before the battery charging process starts, whereas the secondary-side circuit resonant frequency is identified during the charging process without influencing it. To verify the validity of the proposed method, an IPT prototype with 48-V charging voltage and 4-A charging current is implemented. The experimental results indicate that the estimated parameter set provides fast and accurate output voltage and current control.

The design of a wireless power transfer system with double rectangular coils for 11 kW power transfer is considered. System modeling and numerical calculation of the system parameters are described. Coils are made from available Litz wire, which has a smaller than necessary diameter for the required power. Thus, a setup with double layer coils was developed, which resulted in a modified design. Starting from a system consisting of coupled coils, as suggested by the standard for wireless power transfer Level 3 in class Z1, different coil and ferrite shield layouts were tested in numerical simulations, and their parameters were calculated. The prototype was constructed based on the simulated model with the best results and properties. Numerical results were verified by laboratory measurements, and a successful power transfer at 11 kW was achieved.

In this paper, a low-cost, Raspberry Pi based imaging system is proposed as compact standalone interrogation unit for analysis of fiber specklegram sensors. Standard methods for specklegram analysis are based on image correlation. Proposed imaging system is used for both capturing specklegram images at the output of the standard telecommunication optical fiber and for correlation analysis. Experimental setup for controlled mechanical deformation of the optical fiber is designed and zero-normalized cross-correlation, structural similarity and normalized mutual information score correlation methods are implemented and compared in order to verify proposed Raspberry Pi based imaging system functionally. A statistical method for detection of region of interest is used for dynamic output range extension. Additionally, to further extend dynamic range and increase linearity, correlation output is provided as difference of correlation coefficient for two reference samples located at the ends of measurement range.

Negative temperature coefficient (NTC) chip thermistors were thermally coupled to form a novel device (TCCT) aimed for application in microelectronics. It consists of two NTC chip thermistors Th1 and Th2, which are small in size (0603) and power (1/10 W). They are in thermal junction, but concurrently they are electrically isolated. The first thermistor Th1 generates heat as a self-heating component at a constant supply voltage U (input thermistor), while the second thermistor Th2 receives heat as a passive component (output thermistor). The temperature dependence R(T) of NTC chip thermistors was measured in the climatic test chamber, and the exponential factor B10/30 of thermistor resistance was determined. After that, a self–heating current I1 of the input thermistor was measured vs. supply voltage U and ambient temperature Ta as a parameter. Input resistance R1 was determined as a ratio of U and I1 while output thermistor resistance R2 was measured by a multimeter concurrently with the current I1. Temperatures T1 and T2 of both thermistors were determined using the Steinhart–Hart equation. Heat transfer, thermal response, stability, and inaccuracy were analyzed. The application of thermally coupled NTC chip thermistors is expected in microelectronics for the input to output electrical decoupling/thermal coupling of slow changeable signals.

This paper presents a comprehensive analysis of the dead-time effects in wireless power transfer systems based on LCC-S topology. In these systems operating at high frequencies, the ratio of dead-time versus the operating period becomes critical, and the dead-time issue can cause certain problems regarding power quality, efficiency, and output voltage ripple. The impact of input quantities such as voltage and switching frequency on the efficiency and output power of the LCC-S-tuned WPT system was also investigated. The optimal combination of these parameters used to achieve the maximum efficiency for a target output power and to set the appropriate value of the dead time were determined by running multiple simulations using the MATLAB R2023b software platform. It was also shown that the output voltage remained unchanged with and without a load and up to 1200 ns of dead-time, which provides a simple implementation of the corresponding mathematical model. In the recommended interval of 600–1500 ns, the influence of the dead-time on the value of the output voltage amplitude is less than 10%. The validity of the proposed method was confirmed through the implementation of the experimental prototype, a 5 kW wireless power transmission system, and the obtained results were in accordance with the simulation results.

The focus of this research is on designing a longitudinally excited lightweight metastructure that consists of external units distributed periodically, each enhanced with internal oscillators to serve as vibration absorbers. The metastructure initially exhibits uniformity, with all absorbers being identical to each other, being comprised of a cantilever that is integrated into the external parts of the metastructure, with each cantilever containing a concentrated mass block at its tip. Despite its simplicity and suitability for 3D printing, the design of the absorbers could not be kept in the original form when previous theoretical attempts were made with a view to achieving maximal vibration attenuation efficiency around the second resonance. To overcome this shortcoming and keep the absorbers in the original shape, this study undertakes a machine learning methodology to mitigate vibrations near the second resonant frequencies itself, as well as around the first and second resonant frequencies simultaneously. The newly designed metastructure is manufactured, and its advantageous vibration mitigation capabilities are experimentally verified qualitatively. Additionally, physical insight into the configuration and arrangement of the redesigned absorbers in the newly designed metastructure is provided.

A novel device called thermal coupling of NTC chip thermistors was made by combining two electrically isolated chip thermistors Th-1 and Th-2 having small dimensions (0603) and small power (1/10 W). The first thermistor Th1 (input thermistor) is self-heating at a constant supply voltage U - it generates heat while the second thermistor Th2 is passive (output thermistor) - it receives heat. Thermistors are electrically insulated, but thermally coupled. The temperature dependence of NTC chip thermistors R(T) was measured and exponential factor of thermistor resistance B was determined. After that, current I-1 of self-heating thermistor as a function of supply voltage U and using resistance R-1 of input thermistor was determined. The electrical resistance of output thermistor R-2 was measured by multimeter at the same time as the current of input thermistor. Using the Steinhart - Hart equation the temperature T-1 and T-2 of both thermistors were determined. The application of novel thermistor junction is expected in power microelectronics for electrical decoupling/thermal coupling of input to output slowly changeable signals.

A pair of small disk negative thermal coefficient (NTC) thermistors were joined together laterally using a thin layer of silicon resin between them to form a novel thermally coupled device (TCT). The epoxy coating on disk thermistors enables concurrent galvanic isolation and thermal coupling. Input thermistor Th1 in the coupled pair was self-heated at constant voltages and acts as heat transmitter while the output thermistor Th-2 acted as a heat receiver through the epoxy layer and silicon resin. Small NTC disk thermistors with different nominal resistances were produced out of nickel manganese and modified nickel manganese powder. The disk thermistor resistances and the thermistor exponential temperature factor B were measured in the climatic test chamber. The input power, resistance, and temperature of both disk thermistors were measured at different ambient temperatures as a function of input voltage and time. The temperature of thermistors Th1 and Th-2 (input and output) was determined using the Steinhart-Hart equation. The TCT device sensitivity, stability, and inaccuracy were also analyzed. The applications of disk TCT devices are based on the measuring of output temperature versus input power in automotive electronics, home appliances, and power convertors.

There is no one-size-fits-all solution for global energy sustainability. It is affected by a country's policies, resources, financing opportunities, the attention given to it, and the degree to which other pressing issues, such as poverty and access to power, are addressed in each country. This paper used 28 indicators to assess a country's energy sustainability. These indicators ranged from CO2 per capita emissions to the share of electricity production from wind. The indicators were adjusted so that the lower values were more sustainable. 31 countries were selected. Kohonen's self-organizing maps were used to present this 28-dimensional model in a 2D map. This algorithm is a type of artificial neural network trained by unsupervised learning. Eight clusters of countries were found through the analysis using the four-light traffic panel, where green is the most sustainable, followed by blue, yellow, and red. The closeness on the map does not guarantee that two countries will be in the same cluster. Three color matches and closeness were the criteria for the creation of clusters. The energy transition from the map's lower to upper sides is plainly visible. Red clusters make up the lower side, while green clusters make up the top. One blue cluster and two yellow clusters are located between them. The algorithm converged in the 133rd iteration; the quantization error reached 0 and the topological error reached a value of 25. This method can be used to visualize how far or close a country is to the best achievers. It shows which parameters can or should be improved and what the world trend is. If there is a trend, cost-effective solutions are frequently present.

U ovom radu, predstavljen je proces razvoja softvera i test okruženja čiji je cilj pronalaženje defekata i poboljšanje kako kvaliteta tako i robusnosti razvijenog softvera. Priliko testiranja korišćeno je više test nivoa kako bi se otkrili potencijalni defekti u svim fazama razvoja. Prilikom razvoja softvera korišćen je V model.

Noise, illumination, temperature, and pressure are the primary external factors influencing the working environment and employee productivity.Physical variables were investigated in this paper over three weeks to determine whether the printing laboratory is suitable for students' practical training and employees' productive work.The A-weighted Sound Pressure Levels in decibels of different types of machines were determined.The lowest measured Leq level was 63.902.45dB(A), while the highest was 80.503.90dB(A).Because the mean value of the noise levels obtained for all investigated machines exceeded the acceptable level for laboratories and classrooms, as stated in Serbian guidelines, a frequency analysis at the 1/3 octave band was performed.The frequency spectra of the machines operating daily are comparable to the spectrum of human speech, resulting in impaired communication, primarily between students and professors during laboratory classes.The horizontal illumination on worktables in the first room ranged from 206.5 to 393.75 lx.The values in the second room, where student desks are located, ranged from 141.8 to 297 lx, with a mean value of 201.810.1 lx, significantly lower than the range recommended for classrooms and laboratories.The findings of this research indicate that the measured values of the aforementioned parameters significantly vary from what is considered appropriate for educational settings.Although most students and professors do not perceive this ambient atmosphere as disturbing, it stimulates the organic system and negatively affects overall health.

A pair of thick-film segmented thermistors with negative temperature coefficient (NTC) were joined together (back-to-back) to form thermally coupled device. The alumina substrate enables very high galvanic insulation of thermistors and thermal coupling at the same time. The input thermistor ${R}_{{1}}$ in the coupled pair was self-heated at constant voltages and the output thermistor ${R}_{{2}}$ was a heat receiver through the alumina substrate. Custom-designed NTC thick-film thermistor pastes were made out of nickel manganese and modified nickel manganese. Thermistor electrical resistances were measured in a climatic test chamber and the thermistor exponential temperature factor ${B}$ was determined for both pastes. The TCT device was electrically characterized at different ambient temperatures. The input power, heat transfer, resistance, and temperature of both thermistors were measured as a function of input voltage and time. The input and output thermistor temperatures ${T}_{{1}}$ and ${T}_{{2}}$ were obtained using the thermistor resistance and the Steinhart–Hart equation. The device sensitivity and measuring inaccuracy were analyzed. The main advantage of TCT is thermal coupling/electrical decoupling. The applications of TCT device are seen in automotive electronics, home appliances, and power converters to measure output temperature versus input power.

Ambient air pollution is a very considerable and complex physicochemical and environmental issue. Particulate matter (PM) is one of the fundamental pollutants constituted in ambient air. Rapidly expanding urban transformations in city of Novi Sad, Serbia, produces high concentrations of PM. The vast and growing number of construction sites as pollution emission hotspots induce constant nuisance for the people, build surrounding and environment in total. Serbian legislation has set PM pollution limit values for daily emissions, but the air pollutant registry still does not recognize construction sites as severe sources of PM emergence. Understanding the importance and the effects of PM emission from construction sites is crucial in environmental preservation. For the preparation and application of methods and techniques for prevention and mitigation, suitable environmental pollution modeling needs to be achieved. The aim of the research is to assess and determine the utility of Tier 1 prediction model designed by Environmental Protection Agency and environmental modeling software ADMS URBAN on observed construction sites in Novi Sad, Serbia. Assessing monitoring data confirms construction sites as significant PM10 and PM2.5 pollution sources. Two sets of correction coefficients were calculated for PM10 and PM2.5, using average and median values, 2.56-2.54 and 1.03-0.97 respectively. The research study was for the first time conducted in Novi Sad, Serbia in the case of construction sites.

The monitoring of air quality continues to be one of the most important tasks when ensuring the safety of our environment. This paper aims to look at correlations between different types of pollutants, so that robust air quality measurement systems can be deployed in remote, inaccessible areas, at a reduced cost. The first matter at hand was to design an affordable and portable system capable of measuring different air pollutants. A custom PCB was designed that could support the acquisition of readings of, among others, particulate and CO sensors. Then, correlations between the concentrations of different pollutants were analyzed to identify if measuring the concentration of one type of pollutant can allow the extrapolation of the concentration of another. This particular study focuses on the correlations between the concentrations of particulate matter and CO. Finally, after observing a moderate correlation, it was proposed to measure the concentrations of pollutants that require less expensive sensors, and to extrapolate the concentrations of pollutants that require a more expensive sensor to measure their concentration. The link between particulate pollution and CO concentrations was identified and discussed as the result of this study.

A longitudinally excited metastructure with periodically distributed internal oscillators is considered with a view to determining how the tuning condition between their frequency and the frequency of the metastructure as a whole affects vibration attenuation. First, the mechanical model is created, and the tuning condition related to the first resonance frequency of the metastructure with blocked internal oscillators and the first resonance frequency of internal oscillators themselves is obtained in an original analytical form. Then, this condition is used to design the stiffness of the internal oscillators and they are allowed to oscillate in the metastructure, yielding vibration attenuation around the first resonance. The influence of the number of internal oscillators as well as the mass ratio between the mass of one internal oscillator and external oscillator of the metastructure is investigated. Experimental validations, accompanied with numerical results, of these theoretical results are provided subsequently. In addition, the theoretical concept is extended to other resonances, demonstrating its adaptivity and generality, and these cases are then validated via numerical experiments in FEM simulations.