Radiation Detectors Noise Spectroscopy

Kadmium telurid je velmi důležitý materiál jak základního, tak i aplikovaného výzkumu. Je to dáno zejména jeho výhodnými elektronickými, optickými a strukturními vlastnostmi, které ho předurčují pro náročné technické aplikace. Dnes se hlavně používá pro jeho vysoké rozlišení k detekci a X-záření. Hlavní výhodou detektorů na bázi CdTe je, že nepotřebují chlazení a mohou spolehlivě fungovat i při pokojové teplotě. To způsobuje efektivnější interakce fotonů než je tomu u Si nebo jiných polovodičových materiálů. Obsahem této práce byla analýza a interpretace výsledků získaných studiem šumových a transportních charakteristik CdTe vzorků. Měření ukázaly že odpor homogenní části CdTe krystalů mírně klesá při připojení elektrického pole na vzorku. Při změně teploty navíc dochází k odlišné reakci u CdTe typu p a n. Právě těmto efektům je v práci věnována pozornost. Pomocí šumové spektroskopie bylo zjištěno, že při nízkých frekvencích je u vzorků dominantní šum typu 1/f, zatímco při vyšších frekvencích je sledován generačně-rekombinační šum a tepelný šum. Všechny měřené vzorky vykazovaly mnohem vyšší hodnotu šumu na nízkých frekvencích než udává Hoogeova rovnice. Byly nalezeny a popsány zdroje nadbytečného šumu.Cadmium Telluride is a material of great importance in the fields of both fundamental research and technical applications, because of its structural, optical, electronic and photoelectronic properties. Today the main application of Cadmium Telluride is in high resolution detection of -rays and X–rays. The main advantage of radiation detectors manufactured on CdTe base is that they need no cooling and can operate at the room temperature and there is a more effective interaction of photons in CdTe than in either Si or Ge. The transport and noise characteristics of CdTe samples were studied. The measurements show that the bulk resistance of CdTe single crystals decreases very slowly when the external electric field is applied. n-type samples and p-type samples show different response on the temperature changes. These effects were analyzed. The noise measurements show that dominant noise at low frequencies is type of 1/f noise. At higher frequencies generation-recombination and thermal noise were apparent. All the studied samples have very high value of low frequency noise, much higher than it should have been according to Hooge’s formula. The sources of excess noise were investigated.

Online Assessment Format for BIM Skills at the WorldSkills Russia National Championship 2020: Experiment and Results

This article describes a new online format for WorldSkills Competitions based on Digital Construction-BIM (Building Information Modelling) Skills at the Russian National Final 2020. The COVID-19 epidemic has affected many aspects of our lives. Locked down cities, remote on-line education, mask-wearing in public spaces, are all our today’s reality. As a result, the vast majority of WorldSkills National Championships which initially were planned for 2020 were postponed to 2021, including in Ireland, the UK and most other participating countries. There were new requirements for the 2020 Competition Venues, for infrastructure, and even for Competition Rules due to Covid 19 restrictions. WorldSkills Russia, however, decided to experiment with an online format for the Russian National Championship. During the 2020 Competition, the BIM Skills Team piloted an automated assessment tool which enables a fast and objective process to assess the measurement aspect of the Competitor’s work. This article explains how that new process was developed, piloted and evaluated. As an output we offer conclusions from the pilot and recommendations for further improvement of the on-line format for WorldSkills Competitions. We off pros and cons of the online assessment form and analysis of the first, real automatic assessment tool implementation

Continuous Autonomous UAV Inspection for FPSO vessels

This Master's thesis represents the preliminary design study and proposes the unmanned aerial vehicle (UAV) -based inspection framework, comprising several multirotors with automatic charging and deployment for 24/7 integrity inspection tasks. This project has three main topics. First one describes the operational environment and existing regulations that cover use of UAVs. It forms the basis for proposal of the relevant use-case scenarios. Third part comprises two chapters, where design of concept and framework is being based on the previous factors. It shows that before implementation of fully autonomous inspection system, there is a need to cover both regulatory and technical gaps. It can be explained by the fact that there does not exist any autonomous inspection system today. Thus, this project can be seen as a base for future development of the UAV-based inspection system, as it focuses on creation of a general framework

Investigation of a family of cubic dynamic systems

A family of dynamic systems acting on a real plane x, y has been considered, which polynomial right parts are reciprocal forms of x and y, one is a cubic, and another is a square form. A problem to reveal all topologically different phase portraits possible for these systems in a Poincare circle with coefficient criteria of every portrait’s realization has been solved. A Poincare method of serial mappings – central and orthogonal – has been applied. Qualitative and quantitative results for phase portraits have been given. All stages of a solution process are described

Phase Portraits of Cubic Dynamic Systems in a Poincare Circle

In the proposed chapter, we are going to outline the results of a study on an arithmetical plane of a broad family of dynamic systems having polynomial right parts. Let these polynomials be of cubic and square reciprocal forms. The task of our investigation is to find out all the different (in the topological sense) phase portraits in a Poincare circle and indicate the coefficient criteria of their appearance. To achieve this goal, we use the Poincare method of central and orthogonal consecutive displays (or mappings). As a result of this thorough investigation, we have constructed more than 250 topologically different phase portraits in total. Every portrait we present using a special table called a descriptive phase portrait. Each line of such a special table corresponds to one invariant cell of the phase portrait and describes its boundaries, as well as a source of its phase flow and a sink of it

Unsourced Random Access with the MIMO Receiver: Projection Decoding Analysis

We consider unsourced random access with MIMO receiver - a crucial communication scenario for future 5G/6G wireless networks. We perform a projection-based decoder analysis and derive energy efficiency achievability bounds when channel state information is unknown at transmitters and the receiver (no-CSI scenario). The comparison to the maximum-likelihood (ML) achievability bounds by Gao et al. (2023) is performed. We show that there is a region where the new bound outperforms the ML bound. The latter fact should not surprise the reader as both decoding criteria are suboptimal when considering per-user probability of error (PUPE). Moreover, transition to projection decoding allows for significant dimensionality reduction, which greatly reduces the computation time