Příprava nanokompozitů oxidu kovů v plazmovém polymeru a studium jejich vlastností

Název práce: Příprava nanokompozitů oxidu kovů v plazmovém polymeru a studium jejich vlastností Autor: Oleksandr Polonskyi Katedra: Katedra makromolekulární fyziky, MFF UK Vedoucí doktorské práce: Prof. RNDr. Hynek Biederman, DrSc. Katedra makromolekulární fyziky, Matematicko-fyzikální fakulta, Univerzita Karlova v Praze Abstrakt: Tato práce se věnuje studiu nanokompozitních vrstev Al (Al oxid)/plazmový polymer připravených různými metodami s využitím magnetronového naprašování, plasmové polymerizace a depozice svazku klastrů. Dále byla zkoumána tvorba a depozice nanoklastrů kov/oxid kovu s použitím agregačního klastrového zdroje (GAS). Byl studován vliv nízké koncentrace kyslíku v agregačním plynu na proces depozice Al a Ti klastrů. Vlastnosti nanoklastrů a nanokompozitních vrstev byly studovány různými charakterizačními metodami. Morfologie nanokompozitů byla charakterizována pomocí AFM, TEM nebo HRTEM a SEM. Elementární analýzy a chemické složení vrstev byly studovány pomocí XPS a FTIR. Optická charakterizace připravených vrstev byla provedena pomocí UV-Vis spektroskopie a spektroskopické elipsometrie. Bylo ukázáno, že pomocí GAS lze připravit nanokompozity Al(AlxOy)/C:H. Klíčová slova: nanokompozitní tenká vrstva, plazmový polymer, oxid kovu, nanoklastryTitle: Preparation of Nanocomposites of Metal Oxides in Plasma Polymer and Study of Their Properties Author: Oleksandr Polonskyi Department: Department of Macromolecular Physics, MFF UK Supervisor of the doctoral thesis: Prof. RNDr. Hynek Biederman, DrSc. Department of Macromolecular Physics, Faculty of Mathematics and Physics, Charles University in Prague Abstract: This thesis is devoted to a study of nanocomposite films Al (Al oxide)/plasma polymer prepared by various techniques using magnetron sputtering, plasma polymerization and cluster beam deposition. The formation and deposition of metal/metal oxide nanoclusters using a gas aggregation cluster source (GAS) was also considered. The role of low concentration of oxygen in the aggregation gas on the process of Al and Ti cluster deposition was studied. Properties of the nanoclusters and nanocomposite films were characterized by various techniques. Morphology of the nanocomposites was examined by AFM, TEM or HRTEM and SEM. Elemental analysis and chemical composition of the films were studied by XPS and FTIR. Optical characterization of the prepared films was done by UV-Vis spectroscopy and spectroscopic ellipsometry. It has been shown that using GAS nanocomposite Al(AlxOy)/C:H may be prepared. Keywords: nanocomposite thin film, plasma polymer, metal...Katedra makromolekulární fyzikyDepartment of Macromolecular PhysicsMatematicko-fyzikální fakultaFaculty of Mathematics and Physic

Enhancing composition control of alloy nanoparticles from gas aggregation source by in operando optical emission spectroscopy

The use of multicomponent targets allows the gas‐phase synthesis of a large variety of alloy nanoparticles (NPs) via gas aggregation sources. However, the redeposition of sputtered material impacts the composition of alloy NPs, as demonstrated here for the case of AgAu alloy NPs. To enable NPs with tailored Au fractions, in operando control over the composition of the NPs is in high demand. We suggest the use of optical emission spectroscopy as a versatile diagnostic tool to determine and control the composition of the NPs. A strong correlation between operating pressure, intensity ratio of Ag and Au emission lines, and the obtained NP compositions is observed. This allows precise in operando control of alloy NP composition obtained from multicomponent targets

Methods for assessing the impact of bandwidth of control channels on the quality of telecommunications networks in the transmission of data packets of different types

Abstract: It is known that since the early 2000s there has been a rapid increase in data traffic and a significant increase in the need for information flows in the process of providing new types of telecommunications services. This has led to the fact that the existing telecommunications networks have failed or approached the limit of their ability to serve subscribers with specified quality of service. The problem of improving the network architecture of such networks and improving the quality of their operation based on the use of modern methods and principles has arisen and needs constant solution. In this paper the requirements to the bandwidth of the channels of the telecommunication network management system in modern conditions are analyzed and their formalized description is given. In order to assess the bandwidth of the channel of the control network of the telecommunications network on the indicators of the quality of its work in the transmission of various types of data in the work developed and submitted an appropriate methodology. The method is based on mathematical dependences that describe the process of functioning of the telecommunication network management system based on the application of the laws and rules of queuing theory

On the synthesis and processing of nanoparticles by plasmas

A gas aggregation system combined with a magnetron discharge is used to produce nanoparticles (NPs) from metal targets. Here, we presents an overview of the role of different parameters in the TiOx NP synthesis and available challenges in this technique. Particularly, considering the role of duty cycle in the TiOx NP formation at pulsed DC regime indicates that only at a certain duty cycle (for the given condition) a stable NP generation can be achieved. Furthermore, the critical role of oxygen (as a reactive admixture gas) in launching and controlling of the NP synthesis process is studied in detail. Employing an RF hollow electrode discharge for processing of silver NPs leads to charging of most of the NPs, and surprisingly, we found that at high RF plasma powers the contribution of charged NPs in the primary NP beam vanished in the treated beam deposition.Использование систем агрегации газа и магнетронного разряда позволяет получать наночастицы (НЧ) из металлических мишеней. Представлен обзор различных параметров, влияющих на синтез TiOx НЧ, и существующих проблем этого метода. В частности, влияние рабочего цикла на формирование TiOx НЧ в импульсном DC-режиме указывает на то, что стабильное образование НЧ может быть достигнуто только в определённом рабочем цикле (при данных условиях). Кроме того, детально изучена ключевая роль кислорода (в качестве газовой реактивной добавки) в инициировании и контроле процесса синтеза НЧ. Использование ВЧ-разряда с полым электродом для обработки НЧ серебра приводит к зарядке большинства НЧ. Также показано, что в режимах с высокой ВЧ-мощностью, вводимой в плазму, заражённые частицы в первичном пучке НЧ не вносят вклад в осаждение.Використання систем агрегації газу і магнетронного розряду дозволяє отримувати наночастинки (НЧ) з металевих мішеней. Представлено огляд впливу різних параметрів на синтез НЧ TiOx та існуючих проблем цього методу. Зокрема, вплив робочого циклу на формування НЧ TiOx в імпульсному DC-режимі вказує на те, що стабільне утворення НЧ може бути досягнуто тільки в певному робочому циклі (за данних умов). Крім того, детально вивчена ключова роль кисню (в якості газової реактивної добавки) у ініціюванні та контролі процесу синтезу НЧ. Використання ВЧ-розряду з порожнім електродом для обробки НЧ срібла призводить до зарядження більшості НЧ. Також показано, що в режимах з високою ВЧ-потужністю, що вводиться в плазму, заряджені частинки в первинному пучку НЧ не мають впливу на осадження

DEVELOPMENT OF METHODS FOR DETERMINING THE CONTOURS OF OBJECTS FOR A COMPLEX STRUCTURED COLOR IMAGE BASED ON THE ANT COLONY OPTIMIZATION ALGORITHM

A method for determining the contours of objects on complexly structured color images based on the ant colony optimization algorithm is proposed. The method for determining the contours of objects of interest in complexly structured color images based on the ant colony optimization algorithm, unlike the known ones, provides for the following. Color channels are highlighted. In each color channel, a brightness channel is allocated. The contours of objects of interest are determined by the method based on the ant colony optimization algorithm. At the end, the transition back to the original color model (the combination of color channels) is carried out. A typical complex structured color image is processed to determine the contours of objects using the ant colony optimization algorithm. The image is presented in the RGB color space. It is established that objects of interest can be determined on the resulting image. At the same time, the presence of a large number of "garbage" objects on the resulting image is noted. This is a disadvantage of the developed method. A visual comparison of the application of the developed method and the known methods for determining the contours of objects is carried out. It is established that the developed method improves the accuracy of determining the contours of objects. Errors of the first and second kind are chosen as quantitative indicators of the accuracy of determining the contours of objects in a typical complex structured color image. Errors of the first and second kind are determined by the criterion of maximum likelihood, which follows from the generalized criterion of minimum average risk. The errors of the first and second kind are estimated when determining the contours of objects in a typical complex structured color image using known methods and the developed method. The well-known methods are the Canny, k-means (k=2), k-means (k=3), Random forest methods. It is established that when using the developed method based on the ant colony optimization algorithm, the errors in determining the contours of objects are reduced on average by 5–13 %

DEVELOPMENT OF METHODS FOR DETERMINING THE CONTOURS OF OBJECTS FOR A COMPLEX STRUCTURED COLOR IMAGE BASED ON THE ANT COLONY OPTIMIZATION ALGORITHM

A method for determining the contours of objects on complexly structured color images based on the ant colony optimization algorithm is proposed. The method for determining the contours of objects of interest in complexly structured color images based on the ant colony optimization algorithm, unlike the known ones, provides for the following. Color channels are highlighted. In each color channel, a brightness channel is allocated. The contours of objects of interest are determined by the method based on the ant colony optimization algorithm. At the end, the transition back to the original color model (the combination of color channels) is carried out.A typical complex structured color image is processed to determine the contours of objects using the ant colony optimization algorithm. The image is presented in the RGB color space. It is established that objects of interest can be determined on the resulting image. At the same time, the presence of a large number of "garbage" objects on the resulting image is noted. This is a disadvantage of the developed method.A visual comparison of the application of the developed method and the known methods for determining the contours of objects is carried out. It is established that the developed method improves the accuracy of determining the contours of objects. Errors of the first and second kind are chosen as quantitative indicators of the accuracy of determining the contours of objects in a typical complex structured color image. Errors of the first and second kind are determined by the criterion of maximum likelihood, which follows from the generalized criterion of minimum average risk. The errors of the first and second kind are estimated when determining the contours of objects in a typical complex structured color image using known methods and the developed method. The well-known methods are the Canny, k-means (k=2), k-means (k=3), Random forest methods. It is established that when using the developed method based on the ant colony optimization algorithm, the errors in determining the contours of objects are reduced on average by 5–13 %

Wet-Chemical Assembly of 2D Nanomaterials into Lightweight, Microtube-Shaped, and Macroscopic 3D Networks

Despite tremendous efforts toward fabrication of three-dimensional macrostructures of two-dimensional (2D) materials, the existing approaches still lack sufficient control over microscopic (morphology, porosity, pore size) and macroscopic (shape, size) properties of the resulting structures. In this work, a facile fabrication method for the wet-chemical assembly of carbon 2D nanomaterials into macroscopic networks of interconnected, hollow microtubes is introduced. As demonstrated for electrochemically exfoliated graphene, graphene oxide, and reduced graphene oxide, the approach allows for the preparation of highly porous (> 99.9%) and lightweight (<2 mg cm-3) aeromaterials with tailored porosity and pore size as well as tailorable shape and size. The unique tubelike morphology with high aspect ratio enables ultralow-percolation-threshold graphene composites (0.03 S m-1, 0.05 vol%) which even outperform most of the carbon nanotube-based composites, as well as highly conductive aeronetworks (8 S m-1, 4 mg cm-3). On top of that, long-term compression cycling of the aeronetworks demonstrates remarkable mechanical stability over 10 000 cycles, even though no chemical cross-linking is employed. The developed strategy could pave the way for fabrication of various macrostructures of 2D nanomaterials with defined shape, size, as well as micro- and nanostructure, crucial for numerous applications such as batteries, supercapacitors, and filters

ENHANCEMENT IN UV SENSING PROPERTIES OF Zno:Ag NANOSTRUCTURED FILMS BY SURFACE FUNCTIONALIZATION WITH NOBLE METALIC AND BIMETALLIC NANOPARTICLES

In this study, Ag-doped ZnO (ZnO:Ag) nanostructured films were functionalized with silver nanoparticles (Ag NPs), silver-platinum bimetallic nanoparticles (AgPt NPs) and silver-gold bimetallic NPs (AgAu NPs) using a gas phase PVD process based on a Haberland type gas aggregation cluster source and unipolar DC planar magnetron sputtering. Ultraviolet (UV) sensing investigations showed arespectable time constants reduction for rising and decaying photocurrents, as well as an increase for the UV response. Compared to a pristine nanostructured film the surface functionalization with Ag, AgPt and AgAu increased the UV response by factors of 2.7, 3.5 and 4, respectively. The increased performances of the here presented ZnO:Ag nanostructured films functionalized with monometallic and bimetallic NPs based photodetectors are explained by the increased lifetime of photogenerated electron –hole pairs, as well as the formation of nanoscale Schottky barriers at the interface of Au/ZnO:Ag and Pt/ZnO:Ag

Preparation of Nanocomposites of Metal Oxides in Plasma Polymer and Study of Their Properties

Title: Preparation of Nanocomposites of Metal Oxides in Plasma Polymer and Study of Their Properties Author: Oleksandr Polonskyi Department: Department of Macromolecular Physics, MFF UK Supervisor of the doctoral thesis: Prof. RNDr. Hynek Biederman, DrSc. Department of Macromolecular Physics, Faculty of Mathematics and Physics, Charles University in Prague Abstract: This thesis is devoted to a study of nanocomposite films Al (Al oxide)/plasma polymer prepared by various techniques using magnetron sputtering, plasma polymerization and cluster beam deposition. The formation and deposition of metal/metal oxide nanoclusters using a gas aggregation cluster source (GAS) was also considered. The role of low concentration of oxygen in the aggregation gas on the process of Al and Ti cluster deposition was studied. Properties of the nanoclusters and nanocomposite films were characterized by various techniques. Morphology of the nanocomposites was examined by AFM, TEM or HRTEM and SEM. Elemental analysis and chemical composition of the films were studied by XPS and FTIR. Optical characterization of the prepared films was done by UV-Vis spectroscopy and spectroscopic ellipsometry. It has been shown that using GAS nanocomposite Al(AlxOy)/C:H may be prepared. Keywords: nanocomposite thin film, plasma polymer, metal..

Зменшення впливу міжканальних завад на ефективність передачі сигналів в телекомунікаційних системах передачі даних на базі сигналу OFDM

This paper considers the process that forms an interchannel transient interference in the structure of the signal created on the basis of the technology of parallel data transmission and frequency distribution with multiplexing of the phase-modulated signal – the OFDM signal. Based on the analysis of the OFDM signal structure, it was determined that changes in the position and parameters of the carrier symbol from the composition of this OFDM symbol create an interchannel transient interference. A list of OFDM signal parameters that can affect the appearance of interchannel interference and the value of its quantitative value was summarized and presented. A model for assessing the impact of interchannel interference on the efficiency of signal transmission in telecommunication data transmission systems based on the OFDM signal has been developed and proposed. Based on mathematical modeling using this model, the dependence of the quantitative assessment of the magnitude of the interchannel interference on the magnitude of the protective interval for different values of the interchannel value with a different number of signal pre-reception has been established. It is shown that an increase in the value of the interchannel value to 96 subchannels makes it possible to achieve an interchannel transient interference of less than 3 percent with a protective interval of more than 2 ms already with one pre-reception. This is explained by the fact that the increase in the interchannel value makes it possible to reduce the value of the protective interval and minimizes the effect of frequency distortions of the sub-channel of one channel. The data reported in this work and the recommendations substantiated on their basis confirm the possibility of the proposed model for assessing the value of the interchannel transient interference and justifying the recommendations for reducing its impact on the efficiency of signal transmission in telecommunication data transmission systems based on the OFDM signal. The proposed evaluation model can find practical application in improving existing and developing new telecommunication data transmission systems based on OFDM technologyДосліджується процес формування міжканальної перехідної завади в структура сигналу, створеного на базі технології паралельної передачі даних і частотного розподілу з мультиплексуванням фазомодульованого сигналу – сигналу OFDM. На основі проведеного аналізу структури сигналу OFDM; визначено, що зміна положення та параметрів піднесучої з складу даного OFDM-символу створюють міжканальну перехідну заваду. Узагальнено та подано перелік параметрів сигналу OFDM, які можуть впливати на появу міжканальних завад та значення її кількісної величини. Розроблено та запропоновано модель оцінки впливу міжканальних завад на ефективність передачі сигналів в телекомунікаційних системах передачі даних на базі сигналу OFDM. На основі математичного моделювання за допомогою вказаної моделі встановлено залежність кількісної оцінки величини міжканальної завади від величини захисного інтервалу для різни значень міжканальної величини при різній кількості преприйомів сигналу. Показано, що збільшення значення міжканальної величини до 96 підканалів дозволяє досягти міжканальної перехідної завади менше 3 відсотків при величині захисного інтервалу більше 2 мс вже при одному преприйомі. Це пояснюється тим, що збільшення міжканальної величини дозволяє зменшити величину захисного інтервалу та мінімізує вплив частотних спотворень піднесучої одного каналу. Отримані в роботі данні та обґрунтовані на їх основі рекомендації підтверджують можливість запропонованої моделі щодо оцінки значення міжканальної перехідної завади та обґрунтування рекомендацій по зменшенню її впливу на ефективність передачі сигналів в телекомунікаційних системах передачі даних на базі сигналу OFDM. Запропонована модель оцінки може знайти практичне застосування при удосконаленні існуючих та розробці нових телекомунікаційних систем передачі даних на основі технології OFD