Nonlinear left-handed metamaterials

We analyze nonlinear properties of microstructured materials with negative refraction, the so-called left-handed metamaterials. We demonstrate that the hysteresis-type dependence of the magnetic permeability on the field intensity allows changing the material properties from left- to right-handed and back. Using the finite-difference time-domain simulations, we study wave transmission through the slab of nonlinear left-handed material, and predict existence of temporal solitons in such materials. We demonstrate also that nonlinear left-handed metamaterials can support both TE- and TM-polarized self-trapped localized beams, spatial electromagnetic solitons. Such solitons appear as single- and multi-hump beams, being either symmetric or antisymmetric, and they can exist due to the hysteresis-type magnetic nonlinearity and the effective domains of negative magnetic permeability.Comment: 7 pages, 8 figure

Die Holzmodifikation als Chance für einheimische Holzarten im Musikinstrumentenbau

Ein Teil der Arbeit beschäftigt sich mit der Aufarbeitung zur anatomischen und chemischen strukturellen Zusammensetzung von vorrangig einheimischen Hölzern, um schließlich die physikalischen Eigenschaften bzw. deren Differenzen, auch im Unterschied zwischen Laub- und Nadelholz phänomenologisch im Sinne der Struktur-Eigenschafts-Beziehungen zu verstehen. Die Verbesserung von holzphysikalischen Defiziten wird im Rahmen der Arbeit hauptsächlich mithilfe von physikalischen Verfahren erläutert. Dazu erfolgen ausführliche Beschreibungen zum mechanischen Verdichten quer zur Faserrichtung des Holzes, der thermischen Modifikation sowie der Kombination aus beiden Verfahren. Dazu werden sowohl jeweils die verfahrenstechnischen Parameter und Vorgehensweisen als auch die resultierenden anatomischen, chemischen und den damit verbundenen physikalischen Eigenschaftsänderungen erläutert, insbesondere in Abhängigkeit der Parameteranwendung sowie im Unterschied zwischen Laub- und Nadelholz. Darüber hinaus werden bereits durchgeführte Studien zur physikalischen, chemischen und biologischen Holzmodifikation zur Verbesserung der akustischen Eigenschaften von Hölzern und deren möglicher Eignung für den Musikinstrumentenbau vorgestellt, zusammengefasst und jeweils bewertet. Schließlich werden zwei ausgewählte Fallbeispiele beschrieben, welche die Zielsetzung verfolgten, einheimische Holzarten mithilfe der physikalischen Holzmodifikation als Tropenholzersatz in Konzertgitarren und Elektro-Bassgitarren bauteilspezifisch zu verwenden. Der jeweilige Lösungsansatz wurde einerseits durch Einsatz der thermischen Modifikation und andererseits mithilfe einer Kombination aus dem Plastifizieren, mechanischen Verdichten quer zur Faserrichtung und der anschließenden thermischen Modifikation verfolgt. Zur Material- und Instrumentencharakterisierung wurden hierbei verschiedene Testmethoden verwendet und bewertet.:1 Einleitung 1 1.1 Hintergrund und Motivation 1 1.2 Aufbau und Vorgehensweise 5 2 Struktureller Aufbau und relevante Eigenschaften von Holz 6 2.1 Anatomie des Holzes 6 2.2 Chemie des Holzes 18 2.3 Physik des Holzes 39 3 Holzmodifikation 91 3.1 Allgemeines 91 3.2 Verdichten quer zur Faserrichtung 95 3.3 Thermische Modifikation 119 3.4 Kombination: Querverdichten und thermische Behandlung 167 4 Holzmodifikation im Musikinstrumentenbau 185 5 Thermische Modifikation am Beispiel von Klassikgitarren 221 5.1 Grundlagen und Erwartungen 221 5.2 Technologische Umsetzung 230 5.3 Prüfmethoden und Bewertungskriterien 233 5.4 Ergebnisse und Diskussion 247 5.4.1 Allgemeines 247 5.4.2 Optik, Rohdichte und Sorption 248 5.4.3 Mechanische Kennwerte 254 5.4.4 Akustische Kennwerte 262 5.4.5 Objektives Klangverhalten (Anzupftests) 271 5.4.6 Subjektives Klangverhalten (Spieltests) 276 6 Kombination von Querverdichten und thermische Behandlung am Beispiel des Griffbrettbaus für Elektro-Bassgitarren 285 6.1 Grundlagen und Erwartungen 285 6.2 Technologische Umsetzung 291 6.3 Prüfmethoden und Bewertungskriterien 294 6.4 Ergebnisse und Diskussion 296 6.4.1 Allgemeines 296 6.4.2 Optik, Rohdichte, Sorption 298 6.4.3 Mechanische Kennwerte 312 6.4.4 Akustische Kennwerte 315 6.4.5 Objektives Klangverhalten (Anzupftests) 323 6.4.6 Subjektives Klangverhalten (Spieltests) 327 7 Zusammenfassung 330 8 Ausblick 338 Literaturverzeichnis 340 Abbildungsverzeichnis 379 Tabellenverzeichnis 394One part of the thesis deals with the processing of the anatomical and chemical structural composition of primarily native woods in order to finally understand the physical properties and their differences, also in the difference between hardwood and softwood phenomenologically in the sense of structure-property relationships. The improvement of wood-physical deficits is mainly explained within the scope of the work with the help of physical methods. Detailed descriptions are given of mechanical densification across the grain direction of the wood, thermal modification and the combination of both methods. The process parameters and procedures as well as the resulting anatomical, chemical and associated physical property changes are explained, in particular depending on the parameter application and the difference between hardwood and softwood. Furthermore, the work is dedicated to studies that have already taken place on physical, chemical and biological wood modification to improve the acoustic properties of woods and their possible suitability in musical instrument making, summarized and evaluated in each case. Finally, two selected case studies are described which pursued the objective of using native wood species as a component-specific substitute for tropical wood in concert guitars and electric bass guitars with the aid of physical wood modification. The respective solution approach was pursued on the one hand by using thermal modification and on the other hand by using a combination of plasticizing, mechanical densification across the grain direction and subsequent thermal modification. Various test methods were used and evaluated for both material and instrument characterization.:1 Einleitung 1 1.1 Hintergrund und Motivation 1 1.2 Aufbau und Vorgehensweise 5 2 Struktureller Aufbau und relevante Eigenschaften von Holz 6 2.1 Anatomie des Holzes 6 2.2 Chemie des Holzes 18 2.3 Physik des Holzes 39 3 Holzmodifikation 91 3.1 Allgemeines 91 3.2 Verdichten quer zur Faserrichtung 95 3.3 Thermische Modifikation 119 3.4 Kombination: Querverdichten und thermische Behandlung 167 4 Holzmodifikation im Musikinstrumentenbau 185 5 Thermische Modifikation am Beispiel von Klassikgitarren 221 5.1 Grundlagen und Erwartungen 221 5.2 Technologische Umsetzung 230 5.3 Prüfmethoden und Bewertungskriterien 233 5.4 Ergebnisse und Diskussion 247 5.4.1 Allgemeines 247 5.4.2 Optik, Rohdichte und Sorption 248 5.4.3 Mechanische Kennwerte 254 5.4.4 Akustische Kennwerte 262 5.4.5 Objektives Klangverhalten (Anzupftests) 271 5.4.6 Subjektives Klangverhalten (Spieltests) 276 6 Kombination von Querverdichten und thermische Behandlung am Beispiel des Griffbrettbaus für Elektro-Bassgitarren 285 6.1 Grundlagen und Erwartungen 285 6.2 Technologische Umsetzung 291 6.3 Prüfmethoden und Bewertungskriterien 294 6.4 Ergebnisse und Diskussion 296 6.4.1 Allgemeines 296 6.4.2 Optik, Rohdichte, Sorption 298 6.4.3 Mechanische Kennwerte 312 6.4.4 Akustische Kennwerte 315 6.4.5 Objektives Klangverhalten (Anzupftests) 323 6.4.6 Subjektives Klangverhalten (Spieltests) 327 7 Zusammenfassung 330 8 Ausblick 338 Literaturverzeichnis 340 Abbildungsverzeichnis 379 Tabellenverzeichnis 39

Porosity estimation of (Moso bamboo) by computed tomography and backscattered electron imaging

This study aims to investigate and quantify the porosity in the cross section of Phyllostachys edulis (Moso bamboo) culm wall. The porosity results are expected to be utilised in numerical study of heat and moisture transfer. Computed tomography (CT) and backscattered electron (BSE) imaging methods are utilised in this study because these two methods allow measurements of the anisotropic features of bamboo specimens. The results of these two methods can be represented as the function of the real dimension rather than the pore size distribution of the specimen. The specimens are obtained from eight different locations along the Moso bamboo culms. Both internodes and nodes specimens are measured in this study. The average porosity, standard deviation (SD) and coefficient of variation (COV) are calculated for BSE and CT results. Pearson product-moment correlation coefficient (PPMCC) is also calculated in this study to analyse the correlation between the BSE results and CT results. Typical porosity results from 400 sampling points and 10 portions average porosity are analysed in this study. The CT scanning results show similar trend with BSE results. The correlation relationship between BSE and CT results approaches moderate correlation level to strong correlation level. The average porosity of internode specimens is from 43.9 to 58.8 % by BSE measurement and from 44.9 to 63.4 % by CT measurement. The average porosity of node specimens is from 37.4 to 56.6 % by BSE measurement and from 32.1 to 62.2 % by CT measurement

Porosity estimation of Phyllostachys edulis (Moso bamboo) by computed tomography and backscattered electron imaging

This study aims to investigate and quantify the porosity in the cross section of Phyllostachys edulis (Moso bamboo) culm wall. The porosity results are expected to be utilised in numerical study of heat and moisture transfer. Computed tomography (CT) and backscattered electron (BSE) imaging methods are utilised in this study because these two methods allow measurements of the anisotropic features of bamboo specimens. The results of these two methods can be represented as the function of the real dimension rather than the pore size distribution of the specimen. The specimens are obtained from eight different locations along the Moso bamboo culms. Both internodes and nodes specimens are measured in this study. The average porosity, standard deviation (SD) and coefficient of variation (COV) are calculated for BSE and CT results. Pearson product-moment correlation coefficient (PPMCC) is also calculated in this study to analyse the correlation between the BSE results and CT results. Typical porosity results from 400 sampling points and 10 portions average porosity are analysed in this study. The CT scanning results show similar trend with BSE results. The correlation relationship between BSE and CT results approaches moderate correlation level to strong correlation level. The average porosity of internode specimens is from 43.9 to 58.8 % by BSE measurement and from 44.9 to 63.4 % by CT measurement. The average porosity of node specimens is from 37.4 to 56.6 % by BSE measurement and from 32.1 to 62.2 % by CT measurement

Modern Instrumentation and Practical Application of Flame Atomic Emission Spectrometry

Received: 31.01.24. Revised: 24.02.24. Accepted: 24.02.24. Available online: 04.03.24.Despite the advent of atomic absorption spectrometry and inductively coupled plasma, FAES as an analytical tool continues to be efficiently used for the determination of alkali and alkaline earth metals: the method is characterized by simplicity and speed of implementation, and its implementation requires simple and inexpensive equipment. The fields of application of the FAES method are very diverse: these are environmental control, food industry, agriculture, geology, medicine, pharmacology, nuclear and bioenergy, metallurgy and the chemical industry.The modern instrumentation for flame atomic emission spectrometry (FAES) is overviewed: the main technical (composition of the fuel gas used, dispersing element, number of analytical channels, reference channel, detecting element, sampling method) and analytical (determined elements, range of determined concentrations, limits and the accuracy of their determination, the duration of a single measurement, the equired amount of the analyzed sample) characteristics of flame photometers for industrial and clinical use as well as spectrophotometers currently made by various manufacturers such as Sherwood Scientific Ltd., BWB Technologies UK Ltd., Labtron Equipment Ltd., Labnics Equipment Ltd. and JENWAY Ltd (UK); A.KRÜSS Optronic (Germany); Cole Parmer Instrument Company and Labfon Equipment Inc. (USA); Inesa Analytical Instrument Co., Ltd (China); OJSC Zagorsk Optical and Mechanical Plant, Unico-SIS LLC and VMK-Optoelectronics LLC (Russia); Manti Lab Solutions, Labtronics, Systonic, Globe Instruments, Electronics India, Lasany (India). The main areas of application of FAES are presented – bioenergy, agriculture (analysis of plants, soil extracts and fertilizers), mineral raw materials (geology), clinical medicine and pharmaceuticals, food industry, environmental control (analysis of drinking, technical and waste water), nuclear energy, metallurgy and chemical industry, as well as some features and problems associated with the preparation of samples for analysis by the FAES method. The review includes references to works on the practical application of FAES, published mainly from 1998 to 2023

Modern Automatic CHNS/O/X Organic Compound Analyzers

A review of the modern market for the automatic element analyzers widely used to control carbon, hydrogen, nitrogen, sulfur, oxygen and halogens, all of which are the main elements making up the organic compounds content and determining their properties, is presented. The operation principles and device variants of the main blocks of CHNS/O/X analyzers are considered including the sample introduction unit, the reactor unit, the combustion products separation unit and the detection unit. The latest developments of element analyzer manufacturers directed to optimize the individual stages of elemental analysis namely the application of double furnace technology, the incineration in tubes with a high temperature resistant ceramic coating, the application of a flame sensor for monitoring the combustion process, the injection of oxygen under pressure to ensure the efficient combustion of the most complex matrices, the use of separation systems such as already-established classical version of the gas chromatography or the temperature-programming desorption methods as well as the other detection systems are reviewed. The data on the most important technical and analytical characteristics of the analyzers such as Analytik Jena (Germany), Elementar Analysensysteme GmbH (Germany), Thermo Fisher Scientific (USA), PerkinElmer (USA), LECO (USA), EuroVector (Italy), CE Instruments (Italy ), Exeter Analytical (UK) are presented along with the data on the number of injected samples, the number and the design of the reactors, the carrier gases used, the methods of the separation and detection of combustion products, the types and the masses of the samples, the elements and ranges of the determined concentrations, and the duration of the analyses.Дан обзор современного рынка автоматических элементных анализаторов, широко применяемых для контроля содержания углерода, водорода, азота, серы, кислорода и галогенов – основных элементов, входящих в состав органических соединений и определяющих их свойства. Рассмотрены принцип действия и варианты устройства основных блоков CHNS/O/Х-анализаторов: блока ввода образцов, реакторного блока, блока разделения продуктов сжигания и блока детектирования. Отмечены последние разработки фирм-производителей элементных анализаторов, направленные на оптимизацию отдельных стадий элементного анализа: применение технологии сдвоенной печи, сжигание в трубках с устойчивым к высоким температурам керамическим покрытием, применение датчика пламени для контроля за процессом сжигания, инжекция кислорода под давлением для обеспечения эффективного сжигания самых сложных матриц, применение систем разделения с использованием уже ставшего классическим варианта газовой хроматографии или метода температурно-программируемой десорбции, применение различных систем детектирования. Представлены данные о наиболее важных технических и аналитических характеристиках анализаторов таких фирм, как Analytik Jena (Германия), Elementar Analysensysteme GmbH (Германия), Thermo Fisher Scientific (США), PerkinElmer (США), LECO (США), EuroVector (Италия), CE Instruments (Италия), Exeter Analytical (Великобритания): число вводимых проб, число и конструкция реактора, используемый газ-носитель, способ разделения и детектирования продуктов сгорания, тип и масса образца, определяемые элементы и диапазоны их концентраций, длительность анализа

The Politics of Feminism: the Impact of Media Discourse on Reality

Рассмотрен феминистский медиадискурс как новый, устойчивый тренд в русскоязычных СМИ. Выявлено его влияние на российскую действительность.The article considers the feminist media discourse as a new, stable trend in the Russian-language media. Its influence on the Russian reality is revealed