Analele Universității ”Dunărea de Jos” din Galați. Fascicula II, Matematică, fizică, mecanică teoretică / Annals of the ”Dunarea de Jos” University of Galati. Fascicle II, Mathematics, Physics, Theoretical Mechanics

Summary

* * * — 2023-12-18

Cuprins

Direct Optical Particle Tracking - a technique for size distribution assessment

Dan Chicea — 2023-12-13

Nanotechnology, an emerging discipline within material science, has ushered in a new era of engineering by creating nanostructured materials with distinctive properties suitable for a wide range of bioengineering applications. The shape and size of these materials constitute critical variables, determined by the chosen synthesis method and chemical precursors. Silver nanoparticles, synthesized through chemical processes, exhibit antibacterial properties when their size falls within a specific range. However, measuring the size of such nanoparticles, typically in the nanometer to tens of nanometers range, necessitates specialized techniques like Dynamic Light Scattering and Transmission Electron Microscopy. These methods are often limited by assumptions, high costs and longer measurement times. This paper introduces a novel approach utilizing Direct Particle Tracking for assessing particle size distribution in the early stages of nanoparticle synthesis. The study used realistic computer simulations of nanoparticle diffusion, employing the CHODIN code and a specific code for Direct Particle Tracking written for this purpose. The Brownian motion of each particle is recorded, the mean square displacement is computed and the diffusion coefficient, as well. The diameter of each particle is assessed and here from the particle distribution. The results on simulated particle diffusion demonstrate the feasibility of using Direct Particle Tracking as an effective method for size distribution assessment in the initial phases of nanoparticle synthesis. This innovation opens the door to real-time monitoring and control of nanoparticle size in bioengineering applications, promising significant advancements in the field of nanotechnology.

Study of the hydrocarbon-oxidizing activity of bacterioplankton in the Moldavian section of the Prut River

Olga Jurminskaia — 2023-12-13

The paper presents the results of study of the Prut River heterotrophic bacterioplankton. The bi-disciplinary technique was used to assess its hydrocarbon-oxidizing activity, namely: microbiological research was carried out in parallel with hydrochemical investigation of the natural water samples and samples enriched with diesel fuel. The Moldovan-Romanian transboundary section of the Prut River includes various ecological zones, such as the Costești-Stanca Reservoir, the mouth of the Jijia River, the Prut floodplains with the relict Beleu Lake (where oil extraction is carried out despite the fact that it is a protected area of the scientific reserve "Prutul de Jos") and the Prut River mouth with the Giurgiulesti International Free Port. The microbial community of fluvial bacterioplankton corresponds to the specific conditions of each these biotopes, being the most reproducible and adaptable component of the biota. The results obtained in the study of the Prut River bacterioplankton demonstrate the presence of hydrocarbon-adapted microorganisms with a good potential to utilize petroleum products in their metabolic processes.

Heavy metal determination in agricultural soil collected from Brăila County

Alina Sion — 2023-12-13

This is a study conducted on agricultural soil collected from village of Dudescu, Zăvoaia Commune, Însurăței City, Brăila County. In this case soybeans, sunflowers, corn and wheat have been cultivated prior the soil sampling. The soil was analyzed using an ED-XRF and the results indicated, in general, elements concentrations within normal values, indicating a good soil quality. The exceptions in this study, which have exceeded the normal legal values, were: chromium (Cr), nickel (Ni) and arsenic (As). To assess the level of soil pollution, different types of indexes were calculated such as the migration index (MI) and the ecological risk potential (RI).

Study of urban soil collected from a future residential complex area from Galati, Romania

Alina Sion — 2023-12-13

In this paper, soil samples collected from an area where a real estate will develop were studied. The study presents a qualitative and quantitative XRF analysis of samples from an oil factory, Prutul S.A. and old industrial establishment, S.C. Intfor S.A. To assess the level of pollution there were calculated by using Microsoft Excel: total contamination index (HC), Saet summary index after the hazard index (ZC), total pollution index (ZCT) and ecological risk factor (ER). The conclusion for location Prutul S.A. is that the majority of the samples had concentrations below the limits proposed by legislation. In this case, the exceptions are the elements Cr, Ni, and As. Regarding S.C. Intfor S.A., due to the main area of activity, a significant amount of Zn was present, directly affecting the environmental health. Moreover, the presence of Hg, Pb, Cu, Cr, As, V, etc., makes from location F a highly polluted place.

Studies on physical properties of tin oxide films

Nicolae Tigau — 2023-12-13

This paper reports the study of some physical properties of thin films of tin oxide, such as the structural properties, surface morphology and optical transmission and reflection. The thin films of tin oxide were deposited by the method of thermal evaporation under vacuum. Transmission electron microscopy (TEM) was used to study the structural properties and the atomic force microscopy (AFM) method was used to study the surface morphology of thin films of tin oxide. The absorption and extinction coefficients of the investigated thin layers were determined from the transmittance and reflectance spectra recorded in the range of wavelengths between 190 and 1100 nm.

Analysis of the particulate matter long term emissions in Romania by sectors of activities

Simona Condurache-Bota — 2023-12-13

Particulate matter (PM) in the atmosphere is highly relevant due to its far-reaching implications. These tiny solid or liquid particles affect human health, causing respiratory and cardiovascular issues, and even premature death. PM also plays a role in climate change, as some particles contribute to warming, while others have cooling effects, impacting Earth's energy balance. Additionally, PM influences visibility, transportation safety, and ecosystems by depositing on land and water surfaces, altering soil and water quality. Recognizing and monitoring the emissions and sources of PMs by 4 subclasses, from PM2.5 to PM10, but also as TSP (total suspended particles) and individually as BC – black carbon is vital for effective air quality management and mitigating its multifaceted impacts on our environment and well-being. This paper presents an analysis of PMs emissions divided into the 4 classes presented above, for Romania, between 1990-2021, as given by the national report made according to the National Emission reduction Commitments Directive (NECD), which aims to reduce emissions of the main air pollutants. The emission data are presented by national emission sectors, from different industries to different transport types, and also from agricultural activities, and waste management. Relevant averages and trends are quantified and analysed as a reference for real-time data at city level, such that to assess the local pollution level and data accuracy as compared to the national reports.

The ambient noise level in the city of Galati and surroundings

Romana Maria Draşovean — 2023-12-13

The intense and sustained noise to which we are subjected can cause disorders of the auditory system. It affects especially those who suffer from heart problems, but it also has dramatic consequences on the nervous system. It can cause stress, depression, sleep disturbances, cognitive problems and reduced ability to concentrate. The city of Galati is located in the southeastern part of Romania, in the southeastern part of the county with the same name. Galati ranked fifth in terms of noise pollution and unfortunately the local authorities do not run any noise reduction or control program. Through this paper we want to join those who sound the alarm to the authorities to take concrete measures in order to manage and control noise pollution. Data were collected in different areas of the city of Galati and its surroundings. Equivalent noise level was determined with a professional digital acoustic sound level meter with two frequency filters: “A” and “C”. The device can record sound values between 30 dB-130 dB in the 31.3 Hz and 8 kHz range. In general, the sound level exceeded the maximum admissible limit or came close to this value.

Local graph cut in the Image Segmenter app for breast ultrasound images segmentation

Iulia-Nela Anghelache Nastase — 2023-12-13

Breast cancer is among the most common cancers diagnosed in women globally. To help the breast cancer diagnosis, an important step is to accurately segment the breast lesion. To support clinicians in this important step, we analyze the performance of a semi-automated segmentation method based on the Local Graph Cut technique in the Image Segmenter application. Local graph cuts algorithm has the ability to segment more complicated shape by converting the image into a graph representation. It employs seed points set by the user and a cost function. The user identifies certain pixels as foreground and background. The region properties are identified from these pixels and they allow to specify the probability of a pixel belonging to the background or foreground. The graph cut formulation assigns each pixel to a node in the graph and incorrectly segmented pixels are re-assigned until the desired segmentation is completed. To evaluate the segmentation results, the Dice similarity coefficient and Fréchet distance were calculated between the ground truth images and the segmented images. Results show a Dice score of 0.7754 for malignant lesions and 0.8842 for benign lesions. The average Fréchet distance values were 303.28 for malignant and 290.80 for benign lesions, respectively. The experimental results show that the method achieves the best performance and gets the higher Dice score and Fréchet distance for breast benign lesions against malignant lesions.

A review of map-matching algorithms

Corina Dima — 2023-12-13

The public transport system is a key factor for the development of cities and for the satisfaction of citizens. For this reason, public transport management systems based on IT solutions were created. One of the problems that arise in public transport planning is tracking vehicle routes when using GPS information with signal interruptions or erroneous data. In these cases, it is necessary to implement some map-matching algorithms to solve these problems and follow the correct route for good information of the citizens waiting in the stations and for tracking the routes. This work aims to present the main map-matching algorithms and compare them, highlighting their utility and efficiency.

Data processing for administrative systems

Ana Maria Chiriac — 2023-12-13

Digitization of public services is a necessity for the development of administration, especially in big cities. Many studies show that citizens need fast and transparent public services. The process of digilatization has different degrees of development in different countries. Although progress still need to be made, Romania's administrative digitization has developed in recent years. The concept of big data and artificial intelligence algorithms are part of Romanian digital administrative systems. This paper describes the stages of a taxpayer registration in an electronic administrative system in Romania. A case study is also presented in order to highlight the evolution of the state of digitization in Romania during the Covid-19 pandemic when it was necessary to avoid traveling to administrative offices.