Analysis of Selected Artefacts in Diffusion-Based Magnetic Resonance Measurements

Disertační práce pojednává o artefaktech vyskytujících se v difuzně vážených obrazech. V medicínské praxi mohou artefakty způsobovat problémy při diagnostice patologických tkání, proto je cílem jejich eliminace. V práci je nejprve provedena analýza nejčastěji se vyskytujících artefaktů v difuzně vážených obrazech, jsou popsány známé metody eliminace jednotlivých artefaktů. Pro omezení artefaktů způsobených nehomogenitou statického magnetického pole a vlivem vířivých proudů je popsána nově navržená metoda tří měření. Metoda nalezne praktické uplatnění zejména při měření difuzního koeficientu izotropních materiálů. Mezi významné a velmi často se vyskytující artefakty řadíme také magnetickou susceptibilitu. Vlivem rozdílných hodnot magnetické susceptibility na rozhraní dvou materiálů může dojít k nehomogenitám magnetického pole a dokonce až k úplné ztrátě signálu. Proto byla navržena nová metoda měření magnetické susceptibility vzorků magneticky nekompatibilních materiálů, a tedy nevytvářejících MR signál. Navržená metoda měření magnetické susceptibility byla experimentálně ověřena na vzorcích různých tvarů a také různých diamagnetických a paramagnetických materiálů. Dále jsou v práci popsány artefakty jako šum, pohybové artefakty, hardwarová omezení, chemický posuv a závislost difuzního koeficientu na teplotě. Pro přesné měření difuzního koeficientu byl doporučen teplotní systém. Experimentálně bylo zjištěno, že při požadavku na přesné měření s chybou nepřesahující 5 %, by se teplota neměla změnit více než o 0,1 °C. Závěrem práce jsou uvedeny praktické aplikace, při kterých byly uplatněny navržené metody.The presented dissertation thesis analyses artefacts in diffusion-weighted images. In medical practice, the artefacts can impede the diagnostics of pathological tissues and, therefore, need to be eliminated. As the first step within the thesis, an analysis of the most frequent artefacts in diffusion-weighted images is performed, and the hitherto known approaches to artefact elimination are described. In order to facilitate the reduction of artefacts caused by the inhomogeneity of the static magnetic field and induced by eddy currents, a novel three-measurement method is shown. This technique will find application especially in measuring the diffusion coefficient of isotropic materials. At this point, it is important to note that a significant and commonly found problem is the magnetic susceptibility artefact; different magnetic susceptibility values at the boundary between two materials can cause magnetic field inhomogeneities and even complete loss of the signal. Therefore, we designed a novel method for the measurement of magnetic susceptibility in various samples of magnetically incompatible materials, which do not produce any MR signal. The technique was experimentally verified using a set of differently shaped diamagnetic and paramagnetic samples. In addition to the magnetic susceptibility problem, the thesis presents artefacts such as noise, motion-induced items, hardware limitations, chemical shift, and the dependence of the diffusion coefficient on the temperature. To enable precise measurement of the diffusion coefficient, we proposed a thermal system; in the experiment, it was determined that when the measurement error does not exceed 5%, the temperature change should not be higher than 0,1 °C. In the final sections of the thesis, practical application examples involving the designed methods are shown.

Communication & Man-Machine Interface for industrial sensors

V diplomové práci jsou popsány možnosti lokální a dálkové konfigurace senzorů. Pro dálkovou konfiguraci je provedena rešerše nejčastěji používaných průmyslových komunikačních systémů a protokolů. Pozornost je věnována hlavně protokolu HART, který je podrobně rozebrán od fyzické až po aplikační vrstvu. Pro ověření protokolu HART, je navrženo obvodové schéma inteligentního senzoru teploty s čidlem Pt1000. Informace ze senzoru je možné získat v analogové i digitální podobě, díky protokolu HART je možné senzor také konfigurovat. Funkčnost dálkové konfigurace je ověřena pomocí programu HARTWinConf. Pro lokální konfiguraci senzorů jsou popsány ovládací prvky jako tlačítka, maticové klávesnice a dotykové obrazovky. Pro zobrazení měřených hodnot jsou popsány zobrazovací prvky a podrobněji rozebrány znakové LCD displeje a grafické OLED displeje. Pro navržený senzor teploty je vybrán OLED displej DD12864YO-3A. Na displeji je možné zobrazit primární měřenou veličinu – teplotu, proud na smyčce nebo procenta z rozsahu. Na závěr byl proveden test EMI a EMS navrženého inteligentního senzoru.This thesis describes the possibilities of local and remote sensors configuration. Summary overview of the most common Fieldbus and protocols for remote configuration is performed. The focus is mainly dedicated to the HART protocol that is analyzed from the physical layer to the application layer. Circuit diagram and printed circuit board (PCB) of smart sensor with thermistor probe Pt1000 was designed. The HART protocol allows the smart sensor parameters setting as well. The functionality of remote configuration was tested in HARTWinConf program. The control elements for local sensor configuration, such as buttons, matrix keyboards and touchscreens, are described in the following chapter. Representation of the measurement values on display module is introduced too. The most important parameters and aspect of character LCD, graphics LCD and OLED displays are described in greater details. The DD12864YO-3A OLED display was selected to use with designed temperature smart sensor module. The display shows the loop current, the percentage of current range and the primary value - temperature. As the last step the EMI and EMS tests for all modules were performed.

A Detection System with Spider Web Coil-Based Wireless Charging and an Active Battery Management System

The article presents a detection system with spider web coil-based wireless charging. Commonly available metal detectors are sold as handheld systems, which enable only progressive, lengthy, time-consuming search. Importantly, a part of the investigated area can thus be easily missed, and the probability that a metal object will not be found increases substantially. This problem, however, is eliminable via the automatic position tracking mode embedded in the solution obtained through our research. The proposed system facilitates using the spider web coil simultaneously for wireless charging and metal detection by pulse induction. The topology of the detector can emit variable pulse lengths, thus allowing the device to detect more types of metal and to adapt itself to the permeability of the soil. The coil has an branch in a relevant part of the winding to reduce undesirable electromagnetic interference during the charging. On the transmitting side of the topology, impedance matching is included to maintain the maximum spatial gap variability. By changing the position of the receiving side, the output voltage changes; therefore, a high efficiency DC/DC converter is employed. The individual battery cells exhibit different internal resistances, requiring us to apply a new method to balance the cells voltage. The system can be utilized on self-guided vehicles or drones; advantageously, a GPS resending the coordinates to a mesh radio allows for accurate positioning. With the mesh topology, potential cooperation between the multiple systems is possible. The setup utilizes the same coil for wireless power transfer and detection

The Effect of a Spiral Gradient Magnetic Field on the Ionic Conductivity of Water

We discuss the experimental verification of changes in the structure of a liquid water sample inserted in a special spiral “gradient” magnetic field. The magnetic flux components are characterized by a high degree of inhomogeneity; thus, a gradient is found in the monitored section of space. The relevant measurement of the modified, rearranged water sample pointed to a specific ion conductivity lower than that of the untreated water. The results of the experiment, where a sample of demineralized water was exposed to a spiral “gradient“ magnetic field for the period of 5 min, show decreased ion conductivity in the examined samples

A Real Model of a Micro-Grid to Improve Network Stability

This paper discusses the smart energy model of a smart grid using a significant share of renewable energy sources combined with intelligent control that processes information from a smart metering subsystem. An algorithm to manage the microgrid via the demand-response strategy is proposed, accentuating the requirement that the total volume of energy produced from renewable sources is consumed. Thus, the system utilizes the maximum of renewable sources to reduce CO2 emissions. Another major benefit provided by the algorithm lies in applying the current weather forecast to predict the amount of energy in the grid; electricity can then be transferred between the local and the main backup batteries within the grid, and this option enables the control elements to prepare for a condition yet to occur. Individual parts of the grid are described in this research report together with the results provided by the relevant algorithm

New Approaches to Implementing the SmartJacket into Industry 4.0

The paper discusses the possibilities of incorporating sensors and indicators into the environment of an Industry 4.0 digital factory. The concept of Industry 4.0 (I4.0) is characterized via a brief description of the RAMI 4.0 and I4.0 component model. In this context, the article outlines the structure of an I4.0 production component, interpreting such an item as a body integrating the asset and its electronic form, namely, the Asset Administration Shell (AAS). The formation of the AAS sub-models from the perspectives of identification, communication, configuration, safety, and condition monitoring is also described to complete the main analysis. Importantly, the authors utilize concrete use cases to demonstrate the roles of the given I4.0 component model and relevant SW technologies in creating the AAS. In this context, the use cases embody applications where an operator wearing a SmartJacket equipped with sensors and indicators ensures systematic data collection by passing through the manufacturing process. The set of collected information then enables the operator and the system server to monitor and intervene in the production cycle. The advantages and disadvantages of the individual scenarios are summarized to support relevant analysis of the entire problem

WPŁYW WYSOKIEGO NAPIĘCIA NA ROZWÓJ TKANKI ROŚLINNEJ

In our experiment the electrical parameters that affect early somatic embryos (ESEs) were investigated. High voltage was generated by a special high voltage generator. High voltages ranging from 5 to 20 kV and frequency of 1 Hz were applied longitudinal and transversal directly on the Petri dish with 2 days old ESEs of Picea abies for periods of 3 hours every day. One Petri dish was placed directly on top of the high voltage generator and on the other Petri dish were fixed two copper plates for transmission of high voltage. Petri dishes were exposed to high voltage for 14 days. After this time, the influence of high voltage was evaluated. To evaluate the experiment were used biological and chemical methods, which confirmed the changes in the growth of ESEs.W naszym eksperymencie badane były parametry elektryczne, które wpływają na wczesne zarodki somatyczne (ESE). Wysokie napięcie wytworzono za pomocą specjalnego generatora. Wysokie napięcie, z przedziału od 5 do 20 kV i częstotliwości 1 Hz przykładano podłużnie i poprzecznie bezpośrednio do szalki Petriego z 2 dniowymi wczesnymi zarodkami somatycznymi Picea abies, codziennie na okres 3 godzin. Jedną szalkę umieszczano bezpośrednio na górnej części generatora wysokiego napięcia, a na drugiej szalce umieszczono dwie płytki miedziane do przenoszenia wysokiego napięcia. Szalki Petriego poddano działaniu wysokiego napięcia przez 14 dni. Po upływie tego czasu oceniano wpływ wysokiego napięcia. Do oceny zastosowano metody biologiczne i chemiczne. Potwierdziły one zmiany we wzroście wczesnych zarodków somatycznych (ESE)

Predicting the Optimum Corn Harvest Time via the Quantity of Dry Matter Determined with Vegetation Indices Obtained from Multispectral Field Imaging

Estimating the optimum harvest time and yield embodies an essential food security factor. Vegetation indices have proven to be an effective tool for widescale in-field plant health mapping. A drone-based multispectral camera then conveniently allows acquiring data on the condition of the plant. This article examines and discusses the relationships between vegetation indices and nutritiolnal values that have been determined via chemical analysis of plant samples collected in the field. In this context, emphasis is placed on the normalized difference red edge index (NDRE), normalized difference vegetation index (NDVI), green normalized difference vegetation index (GNDVI), and nutritional values, such as those of dry matter. The relationships between the variables were correlated and described by means of regression models. This produced equations that are applicable for estimating the quantity of dry matter and thus determining the optimum corn harvest time. The obtained equations were validated on five different types of corn hybrids in fields within the South Moravian Region, Moravia, the Czech Republic