Open Photoacoustic Cell for Blood Sugar Measurement: Numerical Calculation of Frequency Response

A new approach for continuous and non-invasive monitoring of the glucose concentration in human epidermis has been suggested recently. This method is based on photoacoustic (PA) analysis of human interstitial fluid. The measurement can be performed in vitro and in vivo and, therefore, may form the basis for a non-invasive monitoring of the blood sugar level for diabetes patients. It requires a windowless PA cell with an additional opening that is pressed onto the human skin. Since signals are weak, advantage is taken of acoustic resonances of the cell. Recently, a numerical approach based on the Finite Element (FE) Method has been successfully used for the calculation of the frequency response function of closed PA cells. This method has now been adapted to obtain the frequency response of the open cell. Despite the fact that loss due to sound radiation at the opening is not included, fairly good accordance with measurement is achieved

Photoacoustics Modelling using Amplitude Mode Expansion Method in a Multiscale T-cell Resonator

The photoacoustic (PA) effect consisting of the generation of an acoustic signal based on the absorption of light has already demonstrated its potential for various spectroscopic applications for both gaseous and solid samples. The signal produced during photoacoustic spectroscopy (PAS) measurement is, however, usually weak and needs to be amplified. This is achieved by using a photoacoustic cell resonator where acoustic resonances are utilized to significantly boost the signal. Therefore, a PA resonator has a significant role in PAS measurement set-ups. When designing or optimizing a new PA resonator, numerical methods are generally used to simulate the photoacoustic signal generation. In this paper, the amplitude mode expansion (AME) method is presented as a quick and accurate simulation tool. The method is used to simulate the photoacoustic signal in a multi-scale T-cell resonator over a wide frequency range. The AME method is based on eigenmode expansion and introduction of losses by quality factors. The AME simulation results are compared and analyzed against the results from the viscothermal method. Reasonably good agreement is obtained between the two methods. However, small frequency shifts in the resonances of the AME method are noted. The shifts are attributed to the location of the dominant mode within the T-cell. The viscothermal method is considered the most accurate method for simulating the photoacoustic signal in small resonators. However, it is computationally very demanding. The AME method provides a much faster simulation alternative. This is particularly useful in the design and optimization of photoacoustic resonators where numerical methods are preferred over experimental measurements due to their speed and low cost.Comment: Comsol Conference 201

Backcoupling of acoustic streaming on the temperature field inside high-intensity discharge lamps

Operating high-intensity discharge lamps in the high frequency range (20-300 kHz) provides energy-saving and cost reduction potentials. However, commercially available lamp drivers do not make use of this operating strategy because light intensity fluctuations and even lamp destruction are possible. The reason for the fluctuating discharge arc are acoustic resonances in this frequency range that are excited in the arc tube. The acoustic resonances in turn generate a fluid flow that is caused by the acoustic streaming effect. Here, we present a 3D multiphysics model to determine the influence of acoustic streaming on the temperature field in the vicinity of an acoustic eigenfrequency. In that case a transition from stable to instable behavior occurs. The model is able to predict when light flicker can be expected. The results are in very good accordance with accompanying experiments

High-Intensity Discharge Lamp and Duffing Oscillator - Similarities and Differences

The processes inside the arc tube of high-intensity discharge lamps are investigated by finite element simulations. The behavior of the gas mixture inside the arc tube is governed by differential equations describing mass, energy and charge conservation as well as the Helmholtz equation for the acoustic pressure and the Navier-Stokes equation for the flow driven by the buoyancy and the acoustic streaming force. The model is highly nonlinear and requires a recursion procedure to account for the impact of acoustic streaming on the temperature and other fields. The investigations reveal the presence of a hysteresis and the corresponding jump phenomenon, quite similar to a Duffing oscillator. The similarities and, in particular, the differences of the nonlinear behavior of the high-intensity discharge lamp to that of a Duffing oscillator are discussed. For large amplitudes the high-intensity discharge lamp exhibits a stiffening effect in contrast to the Duffing oscillator.Comment: 14 pages, 8 figure

Multi-Sided Boundary Labeling

In the Boundary Labeling problem, we are given a set of $n$ points, referred to as sites, inside an axis-parallel rectangle $R$, and a set of $n$ pairwise disjoint rectangular labels that are attached to $R$ from the outside. The task is to connect the sites to the labels by non-intersecting rectilinear paths, so-called leaders, with at most one bend. In this paper, we study the Multi-Sided Boundary Labeling problem, with labels lying on at least two sides of the enclosing rectangle. We present a polynomial-time algorithm that computes a crossing-free leader layout if one exists. So far, such an algorithm has only been known for the cases in which labels lie on one side or on two opposite sides of $R$ (here a crossing-free solution always exists). The case where labels may lie on adjacent sides is more difficult. We present efficient algorithms for testing the existence of a crossing-free leader layout that labels all sites and also for maximizing the number of labeled sites in a crossing-free leader layout. For two-sided boundary labeling with adjacent sides, we further show how to minimize the total leader length in a crossing-free layout

Mach–Zehnder Modulator output in time and frequency domain—calculation and experimental confirmation

The Mach–Zehnder intensity Modulator (MZM), named after Ludwig Mach and Ludwig Zehnder, is based on the corresponding interferometer. It splits light into two counter-rotating partial beams, which are later recombined with a controlled phase difference. The output of the MZM depends on the phase difference of the interferometer paths. This phase difference is usually adjusted by an electrical voltage applied to a Phase Shifter (PS) placed in one of the interferometer arms. For MZM applications in which the wavelength is changing, the applied voltage must be adjusted accordingly. We derived the equations describing the MZM output in the frequency domain for the case of a triangular PS voltage (necessary for a sinusoidal output) and compared the analytical results with measurements. Our setup uses an Optical Parametric Oscillator (OPO) with a tunable wavelength from 3.2–3.5 μm as the light source and a Lithium Tantalate (LT)-PS for the MZM’s phase modulation. The novel insights enable new control methods for MZMs particularly suited for spectroscopic applications where the wavelength is scanned or otherwise altered.PeerReviewe

Determining the most suitable spectral range for TDLS – a quantitative approach

We present a mathematical method which allows determination of an optimal spectral range for gas mixture analysis based on theoretical absorption spectra. The resulting center wavelength is particularly suited for tunable diode laser spectroscopy (TDLS). The procedure contains several steps of numerical calculations which can easily be implemented in almost any programming language. We apply our method to three exemplary mixtures of hydrocarbons and present and validate the individual results.Hochschule für Angewandte Wissenschaften HamburgBundesministerium für Umwelt, Naturschutz, Nukleare Sicherheit und VerbraucherschutzPeerReviewe

Propeller optimization by interactive genetic algorithms and machine learning

Marine propeller design can be carried out with the aid of automated optimization, but experience shows that a such an approach has still been inferior to manual design in industrial scenarios. In this study, the automated propeller design optimization is evolved by integrating human–computer interaction as an intermediate step. An interactive optimization methodology, based on interactive genetic algorithms (IGAs), has been developed, where the blade designers systematically guide a genetic algorithm towards the objectives. The designers visualize and assess the shape of the blade cavitation and this evaluation is integrated in the optimization method. The IGA is further integrated with a support-vector machine model, in order to avoid user fatigue, IGA\u27s main disadvantage. The results of the present study show that the IGA optimization searches solutions in a more targeted manner and eventually finds more non-dominated feasible designs that also show a good cavitation behaviour in agreement with designer preference

Pensamento utópico de Koellreutter e sua matriz hegeliana: a construção de uma cultura planetária

       17  Resumo: Este trabalho é um desdobramento de um projeto de pesquisa em andamento acerca do pensamento estético de Koellreutter. Pretende-se demonstrar as afinidades entre as concepções do compositor e elementos contidos na filosofia de Hegel, sobretudo a concepção universalista de humanidade e a ideia de progresso, na qual a História aparece como processo racional e pré-determinado. Pode-se destacar ainda que o “Oriente” é visto pelo filósofo e pelo compositor como aurora da Humanidade, representando um nível inicial de desenvolvimento do Espírito (Geist), que se revela progressivamente através dos diferentes estágios de desenvolvimento até chegar a uma etapa final, que para o compositor já não é realizada pelo “mundo germânico”, tal como em Hegel, mas por uma sociedade tecnológica universal.  Analisando a correspondência entre Koellreutter e Tanaka, bem como outras fontes elaboradas na Índia e no Japão nas décadas de 1960 e 1970, pretende-se discutir o projeto koellreuttiano de elaboração de uma cultura planetária universal, que realizaria uma síntese a partir da oposição entre um “Oriente”, valorizado por suas tradições musicais complexas, expressões de uma consciência intuitiva, e um “Ocidente”, caracterizado por seu racionalismo fragmentador, do qual teriam derivado uma estética naturalista e o sistema tonal. Para realizar tal crítica, utiliza-se alguns conceitos elaborados por Georgina Born (2000) e John Corbett (2000), que permitem aproximar as criações do compositor de outras realizações utópicas baseadas numa fantasia de transculturação híbrida que, de certo modo, dão continuidade ao orientalismo conceitual inaugurado por John Cage.Palavras-chave: Koellreutter. Utopia. Globalização. Hegelianismo.  Orientalismo. The utopian thinking of Koellreutter and its Hegelian matrix: the construction of a planetary culture Abstract: This paper is an unfolding of a research project in progress about the aesthetic thought of Koellreutter. It is intended to demonstrate the similarities between the composer's ideas and elements contained in the philosophy of Hegel, especially the universalist conception of humanity and the idea of progress, in which History appears as a rational and predetermined process. It can be noted that the “Orient” is seen by both the philosopher and the composer as the dawn of Humanity, representing an initial level of development of the Spirit (Geist) that reveals itself progressively through the different stages of development up to reach a final step, which would not be carried out by the “German world”, as in Hegel’s thought, but by a universal technological society. Analyzing the correspondence between Koellreutter and Tanaka and other sources produced in India and Japan during the sixties and seventies, we intend to discuss Koellreutter’s project of constructing an universal global culture, which would be a synthesis resulting from the opposition between an "Orient", valued for its complex musical traditions seen as expressions of an intuitive consciousness, and an "Occident", characterized by its fragmenting rationalism, from which would have derived a naturalistic aesthetic and the tonal system. Some concepts developed by Georgina Born (2000) e J. Corbett (2000) were used to make such discussion, as they allow us to put the composer’s works aside to other utopian achievements based on a fantasy of  hybrid transculturation that, in a certain way, give continuity to a conceptual Orientalism started by John Cage. Keywords: Koellreutter. Utopia. Globalization. Hegelianism. Orientalism.

A produção do saber (etno)musicológico e a questão da significação musical diante de suas determinações

This paper takes Boaventura de Souza Santos‟s analysis of abyssal thinking and his consideration of the distinctions drawn by that thought through its manifestations as a point of departure in order to reveal the importance of other knowledge situated beyond the invisible borders that established distinctions between metropolitan and colonial realities. Bringing the reflection on the knowledge produced by abyssal thinking to the field of (ethno)musicology, one seek, from a South-South dialogue with the Indian Marxist theorist Aijaz Ahmad and the incorporation of contributions from the social sciences and sciences of language (semiotics and semiology), to face the questions of musical signification and of the determination of the theories of knowledge, situating both in the context in which they have been produced. Thus, one intends to demonstrate the importance of a politically engaged musicological knowledge, able to move beyond naturalized views of socially built phenomena and to overcome the conformism and major apathy in our days.Este artículo parte del análisis que realiza Boaventura de Sousa Santos sobre el pensamiento abismal y de su consideración sobre la invisibilidad de las distinciones establecidas por este pensamiento a través de sus manifestaciones, con el propósito de revelar la importancia que tienen otros conocimientos situados más allá de los bordes invisibles que establecen las distinciones entre las realidades metropolitanas y coloniales. Llevando la reflexión sobre el conocimiento producido por el pensamiento abismal al campo del saber (etno)musicológico e a questão da significação musical diante de suasdeterminaçõespartir de un diálogo sur-sur establecido como una reflexión del teórico marxista indiano Aijaz Ahmad y de la incorporación de las contribuciones de las ciencias del lenguaje (semiótica y semiología), se busca abordar las cuestiones del significado musical y de la determinación de las teorías del conocimiento, situando ambas en los contextos en los cuales fueron producidas. De este modo, se busca demostrar la importancia de un conocimiento musicológico políticamente comprometido, capaz de moverse más allá de las visiones naturalizadas de los fenómenos socialmente construidos y de contribuir a la superación del conformismo y la apatía preponderantes en nuestros días.Esse artigo parte da análise realizada por Boaventura de Souza Santos sobre o pensamento abissal e de sua consideração acerca da invisibilidade das distinções estabelecidas por esse pensamento através de suas manifestações, visando revelar a importancia de outros saberes, situados além da linha invisível que estabeleceu as distinções entre as realidades metropolitanas e coloniais. Trazendo a reflexão sobre o conhecimento produzido pelo pensamento abissal para o campo do saber (etno)musicológico, busca-se, a partir de um diálogo sul-sul estabelecido com a reflexão do teórico marxista indiano Aijaz Ahmad e da incorporação das contribuições das ciências sociais e das ciências da linguagem (semiótica e semiologia), enfrentar as questões da significação musical e da determinação das teorias do conhecimento, situando ambas no contexto em que tem sido produzidas. Desse modo, pretende-se demonstrar a importancia de um conhecimento musicológico engajado politicamente, capaz de ir além das visões naturalizadas de fenômenos socialmente contruídos e de contribuir para a superação do conformismo e da apatia preponderantes em nossos dias