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Документ Відкритий доступ A Model of a Free-Space Optical Communication Line with a Smart Reflector(КПІ ім. Ігоря Сікорського, 2023) Melnyk, I. I.; Chadyuk, V. O.The article considers a model of a free-space communication line between several closely located points on the terrain that are outside the line of sight. For the rapid deployment of communication lines with a range of up to hundreds of meters, any tall building visible to all callers can be a kind of optical signal repeater. Compared to radio communication channels, an optical communication line has a higher speed of information transmission, is insensitive to electromagnetic interference and is more protected from eavesdropping. To increase the range of the communication line and increase the signal to noise ratio, it is proposed to use a smart reflector based on the mirror of the two-axis scanner, the angular position of which is controlled by the microcontroller. The microcontroller receives information about the angle of incidence of the laser beam on the smart reflector in the form of photoelectric signals. These signals are formed by a position-sensitive photodetector and a lens in front of it. Depending on the angle of incidence of the laser beam, the position of the laser spot focused by the lens on the photodetector changes, and with it, both signals at its output. To facilitate the search of the smart reflector by transceivers, it is suggested to use an LED beacon in it.Документ Відкритий доступ Fuel Cell Hybridizaon Topologies Using Various Energy Storage Technologies(КПІ ім. Ігоря Сікорського, 2023) Bevza, I. O.The main idea of this work is to review and classify the currently existing fuel cell (FC) hybridization topologies with various energy storage technologies (lithium-ion batteries (LIBs), supercapacitors (SCs), and lithium-ion capacitors (LICs)). There are presented generalized topologies of FC hybridization using LIB/SC or LIC. Also, when analyzing the energy storage technologies presented on the market, a comparison was made of LIB, SC, and LIC characteristics in the form of tables and Ragone plot. As a result, perspectives for the development of hybrid FC technologies using LIC were proposed due to the most advantageous characteristics compared to other energy storage methods.Документ Відкритий доступ Generation of Anisotropic Cloud Cover(КПІ ім. Ігоря Сікорського, 2023) Martyniuk, V. I.; Zhuikov, V. Ya.This paper introduces an advanced mathematical model for generating and analyzing cloud cover images, specifically designed to enhance photovoltaic (PV) partial shading studies. The model development involved a detailed analysis of real cloud cover images, with a particular emphasis on capturing their anisotropic spectral characteristics. This was achieved through a combination of spectral analysis and advanced image processing techniques. The research methodologically focused on developing a four-parameter model to accurately represent cloud formations' spectral properties. Key parameters were identified and fine-tuned to match the real cloud formations' characteristics. This involved analyzing the magnitude and phase spectra of the cloud covers and fitting them to a model capable of replicating these properties accurately. A significant part of the research was dedicated to formulating a novel phase spectrum generation technique. This technique was specifically designed to control the degree of similarity between the synthesized and original images, thereby ensuring the model's effectiveness in various simulation scenarios. The process involved manipulating the phase information of cloud cover images while maintaining their high-frequency components to enhance the detail and realism of the synthesized images. The model's accuracy in replicating cloud cover features was tested against traditional spectral synthesis methods. This comparative analysis involved generating cloud cover images using the developed model and established methods, then comparing these images to the original cloud covers in terms of visual similarity and approximation error. Additionally, the model was utilized to generate pseudo-random cloud cover images by varying the phase spectrum parameters. This process ensured that the generated images, while being random, adhered to the spectral characteristics of the original cloud covers. The research methodology also involved a detailed examination of the images' key characteristics, such as direction, length, and density, to ensure fidelity to the original samples. In summary, this paper details an approach to cloud cover image synthesis, with a focus on the accuracy of spectral properties and the development of an algorithm of model parameters estimation. The research highlights the use of advanced spectral analysis and image processing techniques in deriving key model parameters, leading to a significant advancement in cloud imaging for solar energy applications.Документ Відкритий доступ Human Eye Aberrometry Data Generation Using Generative Adversarial Neural Network(КПІ ім. Ігоря Сікорського, 2023) Yaroshenko, M. O.It’s obvious that for development and improvement of methods and apparatus for diagnosis and treatment of optical flaws of human eye at the modelling stage, it’s necessary to have sets of real measurements. However, data requests to clinics are accompanied by substantial amount of bureaucracy procedures and, at the same time, acquired dataset may be too small, which can be critical, for example, for training of neural networks. According to the analysis of existing publications, publicly available datasets of aberrometry data (sets of eye’s refractive flaws) are rare and consist of relatively low number of measurements. But, due to current development state of neural networks, it is possible to generate data based on real measurements. The most common solutions are methods based on the usage of the Generative Adversarial Networks (GAN). This tendency is also relevant for the modern ophthalmology, but no publications aimed at aberrometry data synthesis were found. For this reason, objective of this work is development of solution for generation of sets of human eye’s refractive errors using neural networks. Proposed solution includes generator and critic networks trained according to the Wasserstein GAN with Gradient Penalty (WGAN GP) algorithm. In order to improve training, the method of data augmentation called Data Augmentation Optimized for GAN (DAG) was used, moreover, the possibility of augmentation of aberrometry data in two forms was implemented — for both Zernike coefficient vectors and wavefront pixel images. According to the result’s evaluation, generated data has the distribution close to the real sample (Fréchet distance equals 0.7) and, at the same time, it is neither a copy of real measurements (92% creativity rate) nor duplication of a few aberration sets (diversity metric equals 3.64 which is close to the optimal 3.83). The direction of further improvement includes enhancement of existing architectures of generator and critic, search or creation of bigger training dataset and refinement of data augmentation technics.Документ Відкритий доступ Real-Time Correcon of the Frequency Response of a Public Address System(КПІ ім. Ігоря Сікорського, 2023) Dvornyk, O. O.Correcng the public address (PA) system during a concert event is one of the crucial tasks in ensuring acousc comfort. However, the exisng approaches to such correcon do not allow for real-me adaptaon to changes in the acousc properes of the venue that occur during the event. To address this limitaon, this arcle proposes the use of a mulband compressor. It is shown that a zero-latency VST plugin can serve as a mulband compressor. Pink noise can be used as a test signal for system calibraon. The results of tesng the proposed algorithm, conducted through model and real-world experiments, demonstrate the feasibility and effecveness of the proposed approachДокумент Відкритий доступ Research of the Characteriscs of a Convoluonal Neural Network on the ESP32-CAM Microcontroller(КПІ ім. Ігоря Сікорського, 2023) Sharuiev, R. D.; Popovych, P. V.The paper is devoted to solving the problem of using neural networks for real-time image recognition on lowpower portable devices running on microcontrollers. The ESP-32 CAM microcontroller was used as the target device, on which an artificial neural network was deployed, written using the Python programming language and the Tensorflow library for building neural networks. The performance of the microcontroller and personal computer for object detection using a neural network and their classification were compared in the paper. The image recognition time and percentage of correctly classified objects were compared. The paper shows that the number of training epochs affects the accuracy of object classification in the image. The obtained results show that increasing the number of training epochs increases the accuracy of object recognition using the studied neural network, but a significant increase in the number of epochs does not significantly improve recognition accuracy. The difference in the obtained results for the microcontroller and personal computer image recognition accuracy ranges from 5%.Документ Відкритий доступ Research on the Dynamic Range of Silicon Photodiodes for Optical Pyrometry Applications(КПІ ім. Ігоря Сікорського, 2023) Verbitskyi, D. O.; Voronko, A. O.Optical pyrometry is one of the main non-contact methods for precise temperature measurement of semiconductor wafers for vapour-phase epitaxy from metal-organic compounds (MOCVD). The requirements for the photocell of the pyrometer are due to the peculiarity of the process. In the pyrometer, the silicon photodiode operates in a mode that is characterized by a small bias voltage value, high sensitivity to weak light radiation, and low noise level. The main temperatures used in vapour-phase epitaxy technology depend on the semiconductor material being grown and the process parameters. Typically, process temperatures range from 500 to 1200 °C. A study of the dynamic range of a silicon photodiode for use in optical pyrometry was conducted. It was established that the minimum value of the dark current and the maximum value of the spectral sensitivity are key to obtaining the desired characteristics, namely, sensitivity to thermal radiation at a temperature of 450 °C. The peculiarities of the manufacturing technology of the planar-diffusion structure of the photodiode to achieve the necessary characteristics that ensure the production of photodiode structures with improved parameters are also considered.Документ Відкритий доступ Strategies of Energy-Efficient Active Filtering in the Two Wattmeter Reference Frame(КПІ ім. Ігоря Сікорського, 2023) Kutafin, Yu.V.; Artemenko, M.Yu.Such basic concepts of power theory as apparent power, active current and minimum power losses in the transmission line are defined for a three-phase three-wire system in the shortened two wattmeter reference frame. On the basis of these concepts, two energy-efficient active filtration strategies were developed and verified by virtual experi- ments. The first of them minimizes the power losses of a three-phase three-wire transmission line with different values of its resistances and ensures a unit value of the power factor. The second strategy follows the recommendation of IEEE Std. 1459- 2010 ensures the minimum power loss of the transmission line with symmetrical sinusoidal currents of a three-phase source.Документ Відкритий доступ The Impact of Wind Power and Load Power Fluctuations on Energy Storage Sizing(КПІ ім. Ігоря Сікорського, 2023) Yaremenko, M. K.; Klen, K. S.The study presents a method of taking into account the impact of wind power and load power fluctuations on the energy storage sizing, comprised of batteries of identical capacity. To account the impact, two methods of calculating the difference between wind power generation and load consumption were presented over some time interval: 1st and 2nd order difference methods. Each of the methods can be parameterized and non-parameterized method with and without taking into account parameters respectively, where the parameters are: discharge current, required discharge duration, depth of discharge, battery capacity, Peukert’s constant, discharge time from 100% capacity, ambient temperature and wind power prediction error. Using the parameterized method compared allows to refine the value of the number of batteries. Using the 2nd order difference method compared to the 1st order difference method can significantly reduce the required number of batteries.Документ Відкритий доступ The Method of Preprocessing of ECG Signals for Detecon of Atrial and Ventricular Late Potenals(КПІ ім. Ігоря Сікорського, 2023) Mnevets, A. V.; Ivanushkina, N. H.This article is aimed at analyzing and improving the methods of preprocessing ECG signals for the task of detecting low-amplitude regular components. This study analyzed the main advantages and disadvantages of existing ECG signal preprocessing methods for the detection of late ventricular and atrial potentials. Based on this analysis, a cardiac cycle averaging method was proposed in order to increase the accuracy of detection of late potentials by various algorithms and improve the quality of preprocessing of the ECG signal aimed at detection of low-amplitude components. The main feature of the proposed method is the division of a large number of cardiocycles for averaging into smaller aggregates (epochs), and the subsequent application of linear matrix decomposition to suppress irregular inclusions. Also, when dividing into epochs, it can be used overlapping. It can reduce the difference between epochs, and increase the number of cardiocycles for averaging. The use of this approach allows to minimize irregular inclusions in the ECG signal and increase the accuracy of the selection of low-amplitude late potentials. In addition, the division into epochs and overlapping makes possible to avoid blurring of low-amplitude high-frequency components during averaging as a result of heart rate variability, as well as to improve the quality of averaging with a reduced number of cardiocycles. To test the proposed method, various approaches were used to assess the ECG signal preprocessing. Mostly, we compared the cardiac cycles obtained as a result of different averaging algorithms and the proposed method with the template. To test the averaging method, an artificial ECG signal was developed with existing noise, late ventricular and atrial potentials, heart rate variability, and a high-amplitude component that occurs at a random location every two heartbeats. The template cardiac cycle was obtained from the original artificial signal without any distortion or noise. Firstly, we visually compared and evaluated different averaging methods with the template. Secondly, we calculated the similarity metrics of the late potentials on the averaged cardiac cycle with the late potentials on the template signal. Based on these metrics, the curves of dependence of the similarity values on the amplitude of late potentials on the ECG signal were calculated. Thirdly, we evaluated the impact of the proposed aver aging method on the classification results of various machine learning algorithms on real ECG signals with available late potentials. The overall testing result showed that the proposed averaging method is able to reproduce the morphology of low-amplitude regular components by 10-30% more accurately and improve the classification accuracy by 5-12%.Документ Відкритий доступ Using Information about Experimental Conditions to Predict Properties of Metamaterials(КПІ ім. Ігоря Сікорського, 2023) Krysenko, P. I.; Zoziuk, M. O.In this work, a method of increasing the amount of data for training neural networks is proposed using the possibility of using information about the experimental conditions of measuring the properties of metamaterials. It is shown that the method is flexible and effective. The results of predicting the transmission coefficient of the metamaterial for different angles of incidence of radiation and type of polarization are presented. Using the architecture presented in the work, a high rate of learning and generation of new data was obtained with an error that does not exceed 12% for experiments in one frequency range and does not exceed 31% if all experiments are used for training. The architecture of the neural network and the method by which it is possible to easily change the number and types of experimental conditions are presented.Документ Відкритий доступ Аналіз спектральної характеристики чутливості дифузійних p-i-n фотодіодів на основі високоомного р-Si(КПІ ім. Ігоря Сікорського, 2023) Кукурудзяк, М.С.Зважаючи на потребу ринку в високочутливих кремнієвих p-i-n фотодіодах (ФД) для детектування випромінювання YAG-лазера (довжина хвилі 1,064 мкм), вирішено дослідити методи збільшення їх чутливості, зокрема зміщення максимуму спектральної характеристики чутливості фотоприймача в сторону більших довжин хвиль, а також проаналізувати вплив різних технологічних факторів на її вигляд. Встановлено, що при збільшенні напруги зворотного зміщення зміщується максимум спектральної характеристики в сторону більших довжин хвиль. Також побачено, що при збільшенні часу життя неосновних носіїв заряду та питмого опору кремнію при однаковій напрузі зміщення максимум спектральної характерстики зміщується в сторону більших довжин хвиль. Досягнуто значення максимуму спектральної характеристики 1,01-1,02 мкм. При використанні мезатехнології, яка мінімізує деградацію питомого опору матеріалу, подальше зміщення максимуму не відбувається. Також встановлено, що зміна глибини залягання дифузійних шарів ФД може негативно впливати на рівень шумів.Документ Відкритий доступ Використання згорткової нейронної мережі для прогнозування коефіцієнту пропускання метаматеріалів від їх структури та складу(КПІ ім. Ігоря Сікорського, 2023) Зозюк, М.О.; Юріков, О.І.В цій роботі пропонується використання згортковаої нейронної мережі для прогнозування властивостей метаматеріалів на основі інформації про структуру та фізичний склад метаматеріалів. Основна мета дослідити можливість заміни великої вибірки вхідних даних на велику кількість інформації про елементи вибірки. Основні методи, які були використані – опис метаматеріалу у вигляді 3D об'єкта, запис інформації про склад мета- матеріалів у вигляді додаткових компонентів у векторах об'єкта, представлення експериментальних досліджень у вигляді коефіцієнтів поліному та точок на графіку. Незважаючи на малу кількість даних, отримано достатньо малу похибку для випадку представлення залежності коефіцієнта проходження від частоти у вигляді коефіцієнтів поліному та у випадку представлення даних у вигляді набору точок, та представлено результати прогнозування експериментальних досліджень. Кількість даних може бути збільшена врахуванням умов при яких отримувались експериментальні дані – поляризація, кут падіння, інтенсивність випромінювання і так далі. Основні питання можуть виникнути при підготовці даних для нейронної мережі по причині складнощів при конвертації форматів 3D в потрібний масив даних та врахування всіх обставин, які можуть впливати на експериментальні дослідження.Документ Відкритий доступ Мікромініатюрні сенсори тиску на основі діодних структур(КПІ ім. Ігоря Сікорського, 2023) Клименко, В. A.; Семікіна, Т. В.В роботі проведено детальний аналіз сучасних мікромініатюрних датчиків тиску виконаних на різноманітних діодних структурах. Показані можливі області застосування таких датчиків, їх головні переваги та недоліки. Про ведено дослідження діодних гетероструктур на основі CdS / ZnS / CuS / CdTe та показано перспективність використання датчиків тиску на основі цих матеріалів в якості аналогу існуючих напівпровідникових приладів. На основі проведених експериментальних досліджень обґрунтовано, що ці структури є п’єзоелектричними. Наведені конструктивні схеми досліджених структур та їх вольт-амперні характеристики. Описані можливі області застосування таких структур. Надані конструктивні схеми та параметри отриманих діодних структур можуть бути цікавими для широкого кола фахівців в області сенсорної техніки та автоматизації різноманітних технологічних процесів виготовлення мікроелектронної апаратури. Показано, змінюючи технології виготовлення датчиків та концентрацію хімічних елементів в отриманих плівках можна змінювати чутливість датчика та динамічний діапазон його роботи, пристосовуючи параметри датчика до галузі його застосування в відповідній вимірювальній електронній апаратурі та в системах контролю тиску.