bluuebunny/crossref_metadata_2025 huggingface dataset:
PROTECTING THE ENVIRONMENT AROUND POLISH QUARRIES FROM HARMFUL SEISMIC VIBRATIONS CAUSED BY ROCK BLASTING
Authors: Chrzan Tadeusz
Published: June 2023

The paper presents the legal and scientific conditions for Polish researchers to determine the vibration velocity and the radius of the safe zone of seismic vibrations generated during rock blasting. Until now, in Poland and worldwide, it has been assumed that seismic vibrations generated during rock blasting with explosives [BM] propagate circularly with equal energy in each direction. However, this is not always the case. A theoretical analysis of the variation of the tangential magnitude Vy of the vibration velocity as a function of the change of the direction angle was carried out for a circular distribution of the vibration velocity. It was shown that the value of the vibration velocity component at the same distance from the vibration source depends on the directional angle between the line of the blast holes and the line connecting the centre of the surface of the excavated BM block and the measuring point. New relationships have been given that take into account the directional angle in the calculation of the maximum values of vibration velocity necessary for the determination of the resulting damage in the building from the SWD. A dynamic impact scale [SWD] for the assessment of building damage as the vibration velocity acting on the building increases is given and discussed. Vibration velocity diagrams measured during the excavation of BM rock have been presented for circular distributions in accordance with theoretical predictions. A vibration velocity diagram for an elliptical distribution, inconsistent with a circular distribution, measured during the excavation of BM rock is presented. It is shown that the directionality of the horizontal tangential component of the vibration velocity exists for both circular and elliptical distribution of vibration velocity in rock excavation with explosive BM. The technical safety of the building in the area of seismic vibrations is determined by the vibration velocity included in zone II of the scale of dynamic influences [SWD] Fig.6A ,6B.
TEMPERATURE AND PRECIPITATION REGIME IMPACT ON SPRING BARLEY (HORDEUM VULGARE) GROWTH IN PRIEKUĻI CASE
Authors: Dzedule Līga , Kalvane Gunta , Kalvans Andis
Published: June 2023

In Latvia, the effects of drought and extreme temperatures on spring barley have so far been little studied due to the availability of data and the fact that meteorological conditions are only one of the multi-influencing factors that affect the agricultural sector.Barley usually flowers before or at the same time as ear emergence. During the flowering period high ambient temperatures are critical for yield formation. If the air temperature during flowering is above 22℃ the flowers of spring barley become sterile. From 2004 - 2022, a significant and positive correlation (R = 0,57) was observed between the average maximum daily temperature from sowing to ear emergence and the number of empty flowers in the main spike. A significant negative correlation (R = 0,55) was observed between plant height and the sum of precipitation from sowing to ear emergence and spike length and the sum of precipitation from ear emergence to maturity (R = −0,54), drought also negatively affects tillering rate and number of productive stems per plant.The combination of all the above-mentioned conditions significantly impacts the yield of barley. The following and relevant findings are very important for the agricultural sector, especially in the context of climate change.
DIGITAL TWIN: ORCHARD MANAGEMENT USING UAV
Authors: Zarembo Imants , Kodors Sergejs , Apeināns Ilmārs , Lācis Gunārs , Feldmane Daina , Rubauskis Edgars
Published: June 2023

Orchard management can benefit greatly from the use of modern technology to reach higher yields, decrease costs and achieve more sustainable farming. Implementation or such a smart farming approach into orchard management can be realised via application of unmanned aerial vehicles (UAV) for data collection and artificial intelligence (AI) for yield estimation and forecasting. On top of that, a digital twin of the orchard can be implemented to represent the physical system of the orchard in the digital format allowing implement modern data-driven decision-making based on fruit-growing automation.The aim of this study is to present a digital twin based on application of UAV and AI for orchard management that is being developed as part of a research project lzp-2021/1-0134. At this moment, we are developing a user-centred design which is oriented to satisfy horticulture specialists’ needs for an autonomous monitoring system and to help them in decision-making. Within the framework of this study an enterprise model of orchard management is designed, which supports the digital twin concept and provides autonomous orchard monitoring. The study is scoped with subjects: apples, pears and cherries, and yield management based on orchard monitoring using UAV.
DIGITAL SOLUTIONS FOR A CLIMATE NEUTRAL ECONOMY: INTERNATIONAL FRAMEWORK OF ECO-DIGITAL PROJECTS
Authors: Maksymova Irina , Mietule Iveta , Kulishov Volodymyr
Published: June 2023

The research reveals practical side of a twin green and digital transition in terms of a global path to climate neutral economy. Digitalization is considered as a driving force behind the transition towards a low-carbon economy. The article focuses on wide international experience of IT implementation for industrial decarbonization. Analytical database of the research covers more than 200 different eco-digital projects in various areas of climate regulations given by international organizations. This allows to outline international framework of eco-digital projects based on geolocation, regional features, IT decisions, level of technological support and climate influence. International differentiation of climate-digital projects was established by region. Comprehensive analysis of these data is provided to identify the gap in digital capabilities and climate targets. The rating of IT applied in climate-digital projects was built. As a result, the research proposes key project ways of the twin green and digital transition that are the most attractive for achieving climate neutrality on a global scale.
POLYELECTROLYTE COMPLEX NANOPARTICLES OF SOLUBLE LIGNIN AND CHITOSAN AS INTERFACIAL MODIFIER
Authors: Shulga Galia , Shakels Vadims , Vitolina Sanita , Neiberte Brigita , Verovkins Anrijs
Published: June 2023

A water-soluble non-stoichiometric polyelectrolyte complex (LCP) was obtained as a result of the interaction of oppositely charged kraft lignin and high molecular chitosan by mixing their dilute water solutions. The sizes of the LCP nanoparticles were characterized by a bimodal distribution at pH 6, and their values were essentially smaller than the sizes of the chitosan particles. It was found that the LCP nanoparticles were characterized by remarkably lower values of surface tension at the air-water and the water-organic liquid interface in comparison with the initial biopolymers. With decreasing pH and increasing concentration of the LCP nanoparticles in the water solution, their adsorption ability at the interfaces was enhanced. The interface tension at the water-heptane interface changed non-linearly with increasing the polyelectrolyte complex concentration that was associated with the “saturation” effect. The dependence of the ability of the LPC nanoparticles to stabilize oil-in-water emulsion on pH values of the water phase was found.
SIMULATED ANNEALING METHOD IN THE CLASSIC BOLTZMANN MACHINES
Authors: Grabusts Peter , Uzhga-Rebrov Oleg
Published: June 2023

The classical Boltzmann machine is understood as a neural network proposed by Hinton and his colleagues in 1985. They added noise interferences to the Hopfield model and called this network a Boltzmann machine drawing an analogy between its behaviour and physical systems with the presence of interferences. This study explains the definition of “simulated annealing” and “thermal equilibrium” using the example of a partial network. A technique for calculating the probabilities of transition states at different temperatures using Markov chains is described, an example of the application of the SA - travelling salesman problem is given. Boltzmann machine is used for pattern recognition and in classification problems. As a disadvantage, a slow learning algorithm is mentioned, but it makes it possible to get out of local minima. The main purpose of this article is to show the capabilities of the simulated annealing algorithm in solving practical tasks.
THE USE OF VIRTUAL REALITY SOLUTIONS TO IMPROVE EDUCATIONAL EXPERIENCE FOR IT STUDENTS
Authors: Zigunovs Makisms , Mamchur Dmytro , Kolodinskis Antons
Published: June 2023

The paper is focused on the research on virtual reality solutions which could be used to improve educational experience focusing on IT students. Current state of the art in the field of VR use for educational purposes was analysed. Pros and cons for VR implementation in education were considered. As the solution to enhance educational experience was proposed to integrate VR environment with learning management system in order to automate assessment for mass-learning courses. An example of such integration, a system based on Unity engine for VR laboratory environment development, and Moodle for learning management system, was presented. Experimental results obtained during testing of developed system proved possibility of proposed integration approach and possible benefits from its practical implementation for mass learning courses.
NEED AND EXPECTATIONS FOR LEARNING IN A STEM ENVIRONMENT
Authors: Karaivanova-Dolchinkova Bonka Encheva
Published: June 2023

In the last decade, the need for specialists in the field of engineering and exact sciences emerged in Bulgaria and around the world. This led to the launch of a National Program for the construction of stem centers in schools. From the Veliko Tarnovo region, 16 schools joined the program at different stages, where STEM centers are being built or are already functioning in various subjects, which significantly support the preparation of quality personnel for the Bulgarian economy. A review and analysis of the expectations of teachers and students from work in centers with an engineering focus and training in natural sciences was made. At the next stage, an analysis and evaluation of the effect of the implementation of these innovative centers will be done.
ORGANIZATION OF STUDENT-ORIENTED PEDAGOGICAL STUDIES: ANALYSIS OF STUDENTS LEARNING EXPERIENCES
Authors: Kondratavičienė Renata , Bertašienė Inga
Published: June 2023

With the development of technology, the organization of pedagogical studies is increasingly taking place in a mixed way, when studies in a real classroom are combined with learning in a virtual learning environment. However, regardless of the tools or resources used in the virtual learning environment, for the organisation of student-centred studies the pedagogical aspect remains essential. This need is highlighted in the Lithuanian and European Union documents. The research aim is to analyse the learning experience of pedagogical students. Methods of research: analysis of scientific literature, survey, descriptive statistics, and inference statistics. The article reveals Primary Pedagogy and Early Childhood Pedagogy students' learning experiences in the following aspects: relevance of learning, reflective thinking, interpretation the study process, interacting with the tutor and with peers. The results of a quantitative study (survey) showed that the relevance of learning, reflection and interpretation of the study process depends on the study methods used, the support provided by the tutors and peers.
VIDEO PROJECTS AS A COMPONENT OF INCLUSIVE COMPETENCE OF FUTURE TEACHERS
Authors: Khilya Anna
Published: June 2023

In our paper, we propose to focus on the use of video products in the educational process of teacher education in Ukraine.First of all, it is important for us to present a justification of the features and importance of using video projects as part of theoretical material / educational content / online and offline courses. After all, the use of video projects allows to deepen the knowledge of future teachers, including audiovisual involvement in the perception of terminology, complex elements of teacher organization, legislation or other theoretical aspects.Secondly, we believe that it is worth noting and presenting the experience of Ukrainian students of pedagogical specialties' involvement in video projects (in particular, the creation of a social video, etc.). After all, such work allows you to reassess your own skills in using technology, acquire new knowledge, formulate a strategy for implementing project-based learning in secondary school practice, and build strong cause-and-effect relationships between the knowledge and experience of using it through technology and social media.All of this together allows us to observe the formation of a future teacher who is not separated from the challenges of the technology world, but who uses the opportunities of our time in a harmonious and high-quality way.
INTERNET TRAFFIC ZONE IDENTIFICATION BY BACKPROPAGATION AND PROBABILISTIC NEURAL NETWORKS
Authors: Balabanova Ivelina , Zhorova Teodora , Georgiev Georgi
Published: June 2023

The article proposes an approach based on the concept of Artificial Intelligence for the categorization of urban areas of Internet content by corporate customers. The applicability of different neural apparatus was analyzed as well as three-layer Backpropagation Neural Networks (BPN) and four-layer Probabilistic Neural Networks (PNN) as the most suitable for the purpose of the study were selected. The synthesis of BPN architectures for Internet traffic identification was carried out according to a different number of computing units in the hidden layers with hyperbolic tangent sigmoid, log-sigmoid and linear transfer functions. The variations of a set of specific criteria were examined as Accuracy, Mean-Squared Error, Mean Absolute Error, Correlation coefficients, etc. The selection of PNNs against the defined quality indicators was based on a stepwise increase of the spread indicator of the Kernel functions in a Radial-Basis (RB) structural layer by analogy similar to that applied to BPNs. In the research processes, high levels of neural recognition indicators were established in processing with the Incoming flows of Internet Packages in an Accuracy of over 90.00%.
DEVELOPING COMPUTER ENGINEERING AND INFORMATION TECHNOLOGY UNDERGRADUATES’ LEARNER AUTONOMY: INDIVIDUALISED INSTRUCTION IN ENGLISH CLASSROOM
Authors: Malykhin Oleksandr , Aristova Nataliia , Melikova Susanna
Published: June 2023

The rapid development of information science and technology encourages lifelong learning and requires university graduates to be able to learn throughout their lives and have special abilities which help them search for continuous education and training opportunities. For students who associate their professional lives with computer sciences, learner autonomy is of immense importance since it helps them take full responsibility for success in professional life and career and contributes to the sustainable development of the current fast-moving digital society. As autonomous learners Computer Engineering and Information Technology undergraduates are able to define their goals clearly, to identify the most optimal learning strategies for achieving these goals and for acquiring new knowledge and skills necessary for their further professional development. The present study is aimed at finding out Computer Engineering and Information Technology undergraduates’ viewpoints on effectiveness of individualised instruction for developing their learner autonomy in English classroom. With this in mind, the team of researchers applied a questionnaire to a sample of Computer Engineering and Information Technology undergraduates who study at three higher education institutions of Ukraine. Data collection lasted for three months and took place in September-December 2022. The obtained results clearly demonstrate that individualised instruction delivered through online teaching tools and apps in English classroom enables university teachers to develop Computer Engineering and Information Technology Undergraduates’ learner autonomy effectively.
ANOMALY DETECTION - REVIEW OF METHODS, TOOLS AND ALGORITHMS
Authors: Volkovičs Roberts
Published: June 2023

This paper contains review of algorithms, methods and tools nowadays used for anomaly detection.Anomaly detection is used in many domains of science and industry, some authors classify anomaly detection as data mining and data science tool, others state it is decision support tool under artificial intelligence domain and indeed the use cases of anomaly detection are very different.The article describes the main algorithms used for anomaly detection from perspective of theory of computer science and practical use cases of anomaly detection in different domains of industry. Several paragraphs are dedicated to the frameworks used by one of the most popular and powerful anomaly detection tools available in the market - Microsoft Anomaly detector.
TECHNOLOGICAL ASPECTS OF ACCOUNTING AUTOMATION SYSTEM AS A DECISION SUPPORT SYSTEM
Authors: Chipriyanova Galina , Krasteva-Hristova Radosveta
Published: June 2023

Nowadays all businesses need access to an extensive pool of information. Reporting, financial and accounting analysis, financial planning and budgeting are key factors for market-oriented corporate management and successful business. In the digital economy, strong competition, responsible entrepreneurship and corporate social responsibility the business feels a need for revolution and new decision sciences for complex systems that collect big data, analyze it and create reports that can be used by managers for decision-making. The present study aims to prove that the accounting automation system is an important tool for managing the economic activity of companies, because it mediates the interrelationships between managers/decision-makers, or subjects of management, economic activity and its results, or object of management, in support of Business intelligence, or BI, Data and Analysis, Power Platform, etc. The following research tasks have to be settled for reaching the above-mentioned goal: 1. to analyze the components of decision support systems; 2. to research the types of decision support systems; 3. to demonstrate the impact of the accounting automation system as a decision support system on the optimization and improvement of the working processes and making adequate timely management decisions; 4. to analyze the technological aspects of accounting automation system as a decision support system; 5. to research the challenges and solutions regarding ERP systems and SAP. In the course of the study shall be justified the thesis that the successful business is based on true, accurate and reliable information which is mostly generated by automated accounting system as a decision support system and contemporary information technologies. The results of the research are expressed in establishing the way to ensure and guarantee the unification, acceleration and optimization of the input-processing-output process, analysis, financial modelling, financial planning, etc. about decision support and respectively wealth management.
DESIGN AND PRODUCTION OF A DEVICE FOR BASING AND FIXING CONIC DETAILS IN SINE BAR MEASUREMENTS
Authors: Katsarova Pavlinka , Georgiev Kliment , Vasileva Adelina , Dimitrov Marin
Published: June 2023

The geometric features of the conical parts measured by a sine bar requires special devices for basing and fastening. Basing and fixing conical parts on a sine bar is a problem that can lead to deviations in measurements. In the presented study, a fixture for fixing and basing conical details when measuring with a sine bar is designed and manufactured. The device is designed to facilitate the work of the operator in fixing the workpiece during the measurement, which increases the accuracy of the measurements. The developed structure is designed using SolidWorks. After the completion of the 3D model, a choice of material and technology for 3D printing is made. After that, a 3D printer is used for its production. The manufactured device is tested in laboratory studies. The designed device is installed on the sine bar without changing the measurement methodology. The conducted experiments prove its workability and applicability.
MODELLING AND SIMULATION OF ELECTROPNEUMATIC POSITIONING SYSTEM INCLUDING THE LENGTH OF PNEUMATIC LINES
Authors: Iliev Georgi , Hristov Hristo
Published: June 2023

This paper presents a mathematical model of electropneumatic positioning system including the length of pneumatic lines for the determination of flow and pressure in unsteady operating modes. A simulation model is developed to study the dynamic processes in an electropneumatic positioning system. Simulation of the mathematical models of the screw compressor, proportional directional valve, pneumatic lines, pneumatic cylinder and PID controller were designed in “MatLab Simulink”. The simulation models of the transients in the electropneumatic positioning system at different line lengths from 1m and 10m with stepwise variation of the input setpoint are simulated developed. Graphical comparison is made of the obtained experimental results and simulation model influence of the pneumatic line length on the dynamics of the electropneumatic positioning system are made.
MODELLING AND SIMULATION OF DYNAMIC PROCESSES OF PNEUMATIC LINES
Authors: Iliev Georgi , Hristov Hristo
Published: June 2023

The paper presents the simulation of dynamic processes of pneumatic lines using the program "SIMULINK" from the product " MatLab". Simulation is a process of forming, preparing and entering a mathematical model in a computational environment and obtaining the results of the calculations performed in this environment. The mathematical model of the pneumatic line to be simulated is according to previously presented equations. For the simulation of the dynamic processes, various real parameters of the dimensions and lengths of the pneumatic lines with the corresponding coefficients are introduced into the model. The simulation of the transient responses was carried out with stepwise variation and sinusoidal input signal supplied by the set point device and pneumatic line lengths of 1 m, 5 m and 10 m. The simulation output data were output to the interface in the form of graphs showing the dependence of the observed quantities, the input and output pressure through the pneumatic line, and the input and output flow rates. From the mathematical model and the experiments performed, it can be concluded that the transient responses in the simulations correspond to the dynamic processes of pneumatic lines of different lengths.
MATHEMATICAL MODELING OF THE SEQUENCE OF MACHINING SECTIONS OF COMPLEX SURFACES WHEN MILLING ON A TRIAXIAL CNC MACHINE TOOL
Authors: Salapateva Silviya , Stafanov Bano
Published: June 2023

The idle running times of the working units of a machine tool are the sum of the idle running times for the tool change and for changing the area uder treatment. The paper presents mathematical models, establishing the relationship between the additional time for performing the technological operations with the parameters of both the technological equipment and the object under treatment. The mathematical models for minimizing the idle moves when a tool passes from one machined section to another, allows to reduce the additional treatment time, which, in turn, leads to an increase in the productivity of the process of actual milling.
INFLUENCE OF BASIC PARAMETERS OF THE LASER MARKING PROCESS ON STAINLESS STEEL SAMPLES
Authors: Hristov Veselin , Lazov Lyubomir , Angelov Nikolay , Yankov Emil
Published: June 2023

The role of basic quantities influencing the process of laser raster marking of AISI 304 stainless steel products using a fiber laser was investigated. Some dependencies were found when changing the contrast of the marking when changing the parameters in wide intervals. As the raster step increases, a non-linear decrease in contrast occurs as the rate of contrast decrease. Regarding the influence of the speed on the contrast, it was found that as the speed increases, the contrast of the marking decreases non-linearly, and as the step increases, the speed of the contrast decrease also increases. Above 20 kHz, the frequency has relatively little influence on the contrast, as with increasing frequency the contrast slowly increases and the dependence is almost linear. The effective energy is strongly influenced by the contrast. At effective energy values below 18 kJ/cm2 the contrast of the marking is insufficient for visual perception of a good quality marking, but in the interval from 6 kJ/cm2 to 46 kJ/cm2 the contrast increases very quickly. At values of the effective energy above 100 kJ/cm2, the contrast of the marking hardly changes. The obtained results can be used by the operators of laser systems to evaluate the working ranges and quickly determine the boundary areas of the optimal technological parameters when obtaining a good contrast in the laser marking of stainless steels with a fiber laser.
FEATURES OF COLOR LASER MARKING ON METALS
Authors: Dolchinkov Nikolay Todorov , Petrov Teodor , Petrov Georgi , Tolev Christian , Dimitrov Emanuil
Published: June 2023

In the research carried out at the Rezekne Academy of Technology, the technology for color laser marking on chromium-nickel base and other metal bases was used in industrial production from the point of view of the repeatability and stability of the produced color markings. The study and research was done during the Erasmus internship by the authors at the Academy of Technology in Rezekne, Latvia. For this purpose, an AISI 304 color palette consisting of fifteen colors was developed and implemented. After the practical experiments, the dependence of the obtained colors on the various parameters of the laser processing was analyzed. The resulting colors were then tested using optical, scanning electron and atomic force microscopy, and the configuration of the oxide films was determined by Raman spectroscopy. The resulting colors are of appropriate uniformity, brightness and cover almost all spectral zones, and the resulting colors are of many times better quality than other metallic bases. A color standardization and palette repeatability test was also performed by evaluating the reflectance spectra of the formed colors. The color palette demonstrated high repeatability for all but one particular color. In parallel, the stability of the color markings was studied in terms of environmental, mechanical and chemical resistance. The resulting colors show high resistance to most environmental conditions; however, exposure to very high temperatures and extreme humidity (100 °C, 90%) and to low temperatures and extreme humidity (-40 °C, 90%) results in degradation of several colors. Colored brands show high hardness and excellent mechanical resistance to external influences and exceptional resistance to various chemicals, except for acid solutions and salts.
EXPERIMENTAL STUDY OF SURFACE ROUGHNESS IN VIBRO-IMPACT CUTTING OF OPTICAL SLUGS
Authors: Lengerov Angel , Sabev Sabi , Paliiski Stoyan
Published: June 2023

In the article, experimental studies were carried out with the aim of determining the influence of different modes of vibro-impact cutting modes of optical slugs on the roughness of obtained surfaces. From the results obtained during the measurements and their mathematical processing are evaluated the average sizes and  intervals and the parameters of the roughness of treated surfaces.
STUDY ABOUT THE INFLUENCE OF THE PROCESS PARAMETERS OF VIBRO IMPACT CUTTING OF OPTICAL SLUGS ON THE PRODUCTIVITY OF THE PROCESS
Authors: Levicharov Georgi , Lengerov Angel , Paliiski Stoyan
Published: June 2023

In the article, experimental studies were carried out, contributing to determination of degree of influence of the parameters of the modes of vibro-impact cutting of optical slugs on the productivity of the process. The optimal frequencies of the forced oscillations of the technological system "slug-cut disc" were reported, in which the durability of the tool and the quality of the obtained surfaces are maximum.
INVESTIGATING THE IMPACT OF LASER POWER AND SCAN SPEED ON ENGRAVING ASPEN THERMOWOOD
Authors: Rāviņš Dzintars , Yankov Emil , Adijāns Imants , Lazov Lyubomir , Rāviņš Daivis
Published: June 2023

This study examines the effect of pre-heat treatment on laser engraving of aspen thermowood. We used an infrared CO2 laser with a wavelength of 10640 nm to engrave aspen thermowood samples with different pre-treatment temperatures, including one non-treated sample (base). The samples had a similar moisture content of about 6 - 8%, but exhibited different shades of brown depending on the pre-treatment temperature. The engraving depth and width were measured for each sample, and 8 graphs were constructed to analyze the results. Our findings show that pre-treatment temperature has a significant effect on the efficiency of laser engraving, with higher pre-treatment temperatures resulting in deeper engraving lines. The study provides valuable insights into the optimization of laser engraving parameters for aspen thermowood, and demonstrates the potential of pre-heat treatment to improve the quality of laser-engraved wooden products.
RESEARCH INTO THE ACCURACY OF HOLES IN 3D PRINTING USING TAGUCHI METHOD
Authors: Bakardzhiev Valeri , Sabev Sabi , Chukalov Konstantin , Kasabov Plamen
Published: June 2023

The article discusses the impact of two factors on the accuracy of the hole sizes - print speed and layer thickness in 3D printing. Nine samples of the ABS polymer were printed by using a 3D printer, then the impact of both of the factors on the accuracy of 3D printing of the holes was evaluated. Taguchi's method was applied with the help of DOE in Minitab to evaluate the impact of the two factors.
RESEARCH OF THE PRINCIPAL MODEL OF THE ELECTRIC ENERGY GENERATOR OF THE ELECTRIC CAR (STAGE COMBINATION OF MECHANICAL AND ELECTROMECHANICAL PARTS)
Authors: Matutis Vaidotas , Savulioniene Loreta , Sakalys Paulius , Gzegozevske Laura
Published: June 2023

The article presents the interim results of the ongoing study (http://journals.ru.lv/index.php/SIE/article/view/6884/5683). At this stage, measurements are made with a model in which we combined the mechanical part with the electromechanical part. At the presentation stage, a model demonstrating the principle operation scheme of the patented device has already been constructed as an object of research. A rotating magnet was connected to the impeller (it was rotated by the impeller). The magnet was rotating around the stationary coils and was already inducing an electric current in the coils. In this way, the generated current and generated voltage values can be used as an indicator for evaluating the efficiency of the impeller. The experiments in question are performed with three impellers of different configurations, keeping other conditions analogous. All experiments were performed using only one rotating magnetic ring and one set of stationary coils. The results of experimental measurements show a wide spectrum and possibilities of increasing efficiency and demonstrate the principle of operation of the future device. When designing an impeller with turned wings, two cavities for magnets and coils are already provided, thus preparing for the next step in improving the design of the model under study and increasing efficiency.
RESEARCHING THE PROCESS OF LASER STRUCTURING OF THE SURFACE OF ALUMINUM
Authors: Bulavskis Kevins , Yankov Emil , Lazov Lyubomir , Pacejs Antons
Published: June 2023

In this scientific study, the ability to modify the surface using nanosecond 1064 nm fiber laser by controlling the speed and scanning line step in the marking process was demonstrated. An experimental matrix for laser marking was developed, consisting of 8 columns for marking line step and 5 rows for marking speed. The laser marked surfaces were measured using a laser scanning microscope and compared with the surface as supplied. From the obtained deviations of roughness Ra, Rz and Rq as a function of marking speed and marking line step, graphical dependencies were constructed for comparative analysis. The modified roughness is also compared with the roughness as supplied. Within this research the effect of laser treatment on the hydrophilicity/hydrophobicity of the surface was studied as well. Plots of dependences of the contact angle CA, the marking line step Δx and the overlap coefficient Ksoc are plotted.
IMPROVEMENT OF OPERATIONAL PROCESSES BY ENSURING WORK SAFETY IN PRODUCTION
Authors: Meiste Ruta , Jakštienė Sandra , Lankauskienė Aušra
Published: June 2023

the article analyzes the improvement of operational processes by ensuring the safety of work in production. The problem raised in the research: how to ensure work safety by improving the company's operational processes in production? The object of work is the possibilities of improving operational processes by ensuring work safety. The aim of the work is to analyze the possibilities of improving operational processes by ensuring work safety in production. Job objectives: to analyze the possibilities of improving operational processes by ensuring work safety from a theoretical aspect; to investigate the possibilities of improving operational processes by ensuring work safety in the production company; prepare a plan for the improvement of operational processes by ensuring work safety in production. Research methods: analysis of scientific literature and other informational sources; data collection and systematization method; descriptive analysis method used to report research data; the summarization method is used to evaluate the results of the analysis; the research uses data analysis and observation method.After conducting the research and analyzing the measures applied in the operational processes, ensuring the safety of work in production, a plan for improving the operational processes was prepared and presented, which offers specific measures for increasing the efficiency of the processes and reducing the risk of accidents. The measures implementation plan is designed to solve existing problems in the company's operational processes, offering recommendations on how to reduce or completely eliminate accidents by ensuring work safety. The proposed plan will help minimize the risk of accidents at work by ensuring work safety in operational processes. The created plan for improving operational processes with measures by ensuring work safety and reducing the risk of accidents at work is universal and can be applied in other manufacturing companies that seek to improve operational processes by ensuring work safety
STUDY OF TECHNOLOGICAL CHAINS FOR RAPID PROTOTYPING OF ORTHODONTIC DENTAL PRODUCTS
Authors: Dukova Veselina , Minev Roussi , Yankov Emil
Published: June 2023

The paper presents results from studying the possibilities of digital layering technologies (DLP SLA - Digital Light Projector Stereolithography) for construction of biomedical orthodontics devices (aligners). Experimental data on the mechanical and aesthetical properties (transparency) of the materials used has been studied in comparison with the conventional technologies for producing the aligners - Vacuum Forming (VF). The paper discuss the influence of the design of the devices (e.g. thickness) and technological parameters (e.g. stirring time) of the processes on the mechanical properties and orthodontics functionality of the materials as well as the quality and accuracy of the devices (models and functional prototypes for dental applications).
INVESTIGATION OF THE INFLUENCE OF TECHNOLOGICAL PARAMETERS OF LASER MARKING ON THE DEGREE OF CONTRAST
Authors: Tsvyatkov Petar , Yankov Emil , Lazov Lyubomir , Teirumnieks Edmunds , Pīgožnis Karlis
Published: June 2023

In modern production, each finished product entering the market is identified by a special marking. Each mark must meet requirements such as good coding, easy to see, easy to read by certain readers, stable over time, etc. In the present casting, laser marking of the C75 steel was carried out with a fiber laser with an average power of P = 30 W and a wavelength of λ = 1064 nm. For semi-contrast marking, marking speeds from 100 mm/s to 700 mm/s, average power from 10 to 30 W, raster pitch from 20 µm to 60 µm, scanning frequency from 20 kHz to 150 kHz were investigated as constant parameters are the pulse duration τ =100 ns, number of repetitions N = 1 and defocus Δ f = 0 mm. The influence of the changing parameters on the contrast was established, and experimental dependences were constructed. The achieved research results show that to obtain a high contrast mark, the average power should be above 20 W, the scanning speed up to 300 mm/s, the scanning frequency up to 50 kHz and the raster pitch up to 40 µm.
Site response from ambient noise measurements: New perspectives from an array study in Central Italy
Authors: Milana G. , Barba S. , Del Pezzo E. , Zambonelli E.
Published: June 2023

In this study, we used both spectral and array techniques to investigate microtremor characteristics in an urban area in Central Italy and to relate them to the properties of shallow geological structures.

We made noise measurements for sites located on the various surface geological conditions that can be found in the town of Rieti. Both sediments and bedrock are present at the surface, and the transition zone between them is very narrow and well localized. Using a small area reduced the effects related to the poor knowledge about the distribution of noise sources; using spectral ratio techniques, a good image of resonance frequencies on the alluvial sediments was obtained. Moreover, the use of an array allowed to describe better the morphology of the bedrock and to study Rayleigh-wave dispersion. Starting from the obtained surface-wave dispersion curve, we calculated a velocity model producing both a theoretical dispersion relationship and resonance frequencies for sedimentary layers in good agreement with experimental data.

Our work suggests that the use of array techniques can be very useful to increase the quality of microtremor data, giving new answers to microzoning problems.
Are Lg spectra from NTS explosions self-similar?
Authors: Jones Eric M. , Taylor Steven R.
Published: June 2023

Network-averaged Lg spectra for 106 underground Nevada Test Site (NTS) nuclear explosions (recorded at the four broadband seismic stations operated by Lawrence Livermore National Laboratory) are shown to be approximately self-similar and to scale with cavity radius and scaled-cavity radius. Composite spectra produced by superimposing the spectra of individual tests of nearly identical yields conducted in a single geologic unit (e.g., Tunnel Beds tuff, Yucca Flat, below the water table) have amplitude variability of about a factor of 2. If a master spectrum is chosen that resembles the shape of a particular subgroup of nearly identical NTS explosions, the spectra of all other tests in the database can be superimposed on the master spectrum through the application of a shot-specific amplitude shift and a shot-specific frequency shift. The amplitude shift basically measures the difference between the low-frequency asymptotes of the individual spectrum and the master spectrum, and the frequency shift measures the difference in corner frequencies. We show that, for explosions producing cavities with a narrow range of measured scaled-cavity radii, the amplitude shifts scale with cavity volume. Further, if cavity volume scaling is applied to the amplitude shifts, the residuals are shown to depend on scaled-cavity radius or gas-filled porosity. The residuals (a measure of seismic coupling) appear to show slightly reduced scatter when plotted versus scaled-cavity radius as opposed to gas-filled porosity. The frequency shifts scale approximately as cavity radius to the 3/4 power. Although the NTSLg spectra are approximately self-similar, differences in high-frequency decay and other shape parameters exist. For example, the rate of high-frequency decay is observed to progressively decrease as explosions approach the static water level from above. These differences do not have a significant effect on the connections established between the amplitude and frequency shifts with cavity radius and other source parameters but do suggest source differences of potential interest in discrimination studies.
Observation of shallow anisotropy on local earthquake records at the Garner Valley, Southern California, downhole array
Authors: Coutant Olivier
Published: June 2023

We study very shallow (<200 m) S-wave anisotropy effects on local earthquake seismograms recorded by a vertical array of accelerometers at Garner Valley (Southern California). Using seismic events recorded by sensors buried at depth in the crystalline bedrock (220 m), in weathered crystalline rocks (22 m), and in sediments (15, 6, and 0 m), we analyze the S-wave vertical travel times and polarizations at different depths. Hodograms plotted for horizontal components at S onset exhibit a clear linear and constant polarization independent of both earthquake location and mechanism. This alignment varies with depth and is N 325° ± 13° at 220 m while N 25° ± 20° at 22, 15, 6, and 0 m. (a) For the deep propagation (>220 m), the S-wave direction of polarization at 220 m is identical to the observation obtained on a crystalline outcrop at the KNW USGS stations, 7 km away. Studies conducted on this site concluded to a rock fabric anisotropy due to the alignment of minerals and/or microcracks along the lineation direction. (b) For the shallow (<220 m) propagation, we observe a N 0° ± 20° fast-axis anisotropy with an 8 ± 2% magnitude between 220 and 22 m. The associated Sfast-Sslow travel-time delays roughly correspond to half the dominant period of the signal, and the subsurface linear polarization is interpreted as a degenerated ellipse. The north ± 20° anisotropy fast axis coincides with the maximum horizontal compressive stress associated with the San Andreas fault system. The shallow anisotropy extension corresponds to slow velocities associated with altered granite. It suggests either a stress-induced anisotropy due to pore/crack deformation in an altered (e.g., hydrothermally) medium, or the superposition of two crystalline units having different lineation directions. These data show that in presence of slow 0- to 200-m subsurface layers, shallow anisotropy strongly affects the earthquake surface records in the usual frequency range, below 30 Hz, used in short-period seismology.
Modeling of ground motion from a 1994 Northridge aftershock using a tomographic velocity model of the Los Angeles Basin
Authors: Haase Jennifer S. , Hauksson Egill , Vernon Frank , Edelman Adam
Published: June 2023

The 1994 Northridge mainshock and its aftershocks show a complex pattern of peak accelerations at stations located in the Los Angeles Basin. The waveforms contain multiples of body-wave phases and extensive surface waves at frequencies mostly below 1 Hz. In particular, for stations at distances greater than 18 km, secondary arrivals show larger accelerations than the direct S-wave arrivals. The mainshock waveforms are further complicated by irregularities of the source rupture. We use 2D finite difference to evaluate the effect of lateral variations in seismic velocity on the amplitude of shear-wave energy and to distinguish the effects of source and propagation path. We model waveforms from one aftershock recorded at nine stations deployed along a 60-km-long profile extending into the Los Angeles Basin. We use a two-dimensional slice through the 3D tomography model of the Los Angeles Basin in the 2D finite-difference calculations. These synthetic waveforms fit the aftershock waveforms significantly better than corresponding waveforms determined from simple 1D velocity models. With the addition of a thin low-velocity surface layer above the tomography model, the finite-difference synthetics reproduce most of the important features of the recorded data, in particular, the large-amplitude arrivals 7 to 10 sec following the direct S arrival. These arrivals correspond to the SS arrival, which is sharply refracted at the basin edge, and the S-wave with multiple legs trapped by the dipping near surface gradient. For large earthquakes located either inside or outside the basin, these phases can be the cause of the largest and hence potentially most hazardous shaking in the Los Angeles Basin.
Provisional seismic zoning for ground failures in portions of Los Angeles and Ventura counties following the 17 January 1994 Northridge earthquake
Authors: Real Charles R. , DeLisle Mark J. , McCrink Timothy
Published: June 2023

Provisional seismic hazard zones for earthquake-induced ground failures have been delineated for portions of the three-county area most affected by the Northridge earthquake using a simplified hazard assessment methodology. The procedure integrates surface geology, topography, and groundwater information using GIS technology. While not a replacement for “official” seismic hazard zones, which are based on a more detailed and comprehensive analysis of hazard, these provisional zones will assist in the immediate and cost-effective distribution of postearthquake hazard mitigation funds.
Landslides triggered by the 1994 Northridge, California, earthquake
Authors: Harp Edwin L. , Jibson Randall W.
Published: June 2023

The 17 January 1994 Northridge, California, earthquake (Mw = 6.7) triggered more than 11,000 landslides over an area of about 10,000 km2. Most of the landslides were concentrated in a 1000-km2 area that included the Santa Susana Mountains and the mountains north of the Santa Clara River valley. We mapped landslides triggered by the earthquake in the field and from 1:60,000-nominal-scale aerial photography provided by the U.S. Air Force and taken the morning of the earthquake; these mapped landslides were subsequently digitized and plotted in a GIS-based format. Most of the triggered landslides were shallow (1- to 5-m thick), highly disrupted falls and slides within weakly cemented Tertiary to Pleistocene clastic sediment. Average volumes of these types of landslides were less than 1000 m3, but many had volumes exceeding 100,000 m3. The larger disrupted slides commonly had runout paths of more than 50 m, and a few traveled as far as 200 m from the bases of steep parent slopes. Deeper (>5-m thick) rotational slumps and block slides numbered in the tens to perhaps hundreds, a few of which exceeded 100,000 m3 in volume. Most of these were reactivations of previously existing landslides. The largest single landslide triggered by the earthquake was a rotational slump/block slide having a volume of 8 × 106 m3. Analysis of the mapped landslide distribution with respect to variations in (1) landslide susceptibility and (2) strong shaking recorded by hundreds of instruments will form the basis of a seismic landslide hazard analysis of the Los Angeles area.