scholarly journals In situ identification strategy of thermoacoustic stability in annular combustors

2018 ◽  
Vol 10 (4) ◽  
pp. 351-361 ◽  
Author(s):  
Driek Rouwenhorst ◽  
Jakob Hermann ◽  
Wolfgang Polifke
Keyword(s):  
Cylindrical Symmetry ◽  
Mode Shapes ◽  
Stable Operation ◽  
Combustion System ◽  
Azimuthal Mode ◽  
Annular Combustor ◽  
The Moment ◽  
Output Only ◽  
The Individual

In annular combustion systems, thermoacoustic eigenmodes can manifest as standing waves, traveling waves or some form in between. Which dynamic solution appears in a combustor depends on details, regarding the flow field and (unintentional) breaking of the cylindrical symmetry of the annular combustion system. When these details are unknown, the specific behavior cannot be predicted from the characteristics of a single burner. Due to the (nearly) degenerate nature of the acoustic solution, annular eigenmodes come in pairs with practically the same eigenfrequency. In order to identify the thermoacoustic modes, conventional analysis of a spectral peak from a measurement does not suffice, because the peak is a superposition of the two eigenmodes. A method has been proposed to identify the two eigenmodes of given azimuthal mode order from multiple simultaneous measurements around the circumference of the combustion system. Using output-only identification on the acoustic signals, it is possible to estimate the individual mode shapes, frequencies and growth rates of the co-existing eigenmode pair. In this work, the strategy is applied to experimental data from an annular combustor. A split in the growth rate pair is observed during stable operation, depending on the equivalence ratio and flame-to-flame distance. It shows that in situ identification of annular thermoacoustics can reveal subtle dynamic effects, which is useful for testing and online monitoring of annular combustors. The moment when instability occurs can be foreseen under prevailing conditions, with simultaneous identification of the azimuthal mode structure.

scholarly journals Dynamic Identification and Monitoring of St. Torcato Church

2010 ◽  
Vol 133-134 ◽  
pp. 275-280 ◽  
Author(s):  
Luís F. Ramos ◽  
Murat Alaboz ◽  
Rafael Aguilar
Keyword(s):  
Model Updating ◽  
Experimental Tests ◽  
Dynamic Monitoring ◽  
Mode Shapes ◽  
Fe Model ◽  
Dynamic Identification ◽  
Structural Problems ◽  
The Moment ◽  
Output Only ◽  
The Church

The paper is related to the San Torcato Church, in Guimarães, Portugal. At the moment, the church has significant structural problems due to soil settlements. Cracks can be observed on the main and the lateral façades, the bell-towers are leaning, and the arches in the nave exhibit a failure mechanism with cracks and vertical deformations. Non-stabilized phenomena are present in the structure. To stabilize the damage, a structural intervention is planned to occur soon and the church is already monitored to follow the intervention. The paper clearly presents the problem with emphasis to the dynamic analysis carried out before the structural strengthening, namely: the experimental tests with output-only techniques for frequencies, damping and mode shapes estimation, FE model updating analysis and dynamic monitoring

Modal Analysis of Annular Combustors: Effect of Burner Impedance

2001 ◽  
Author(s):  
Werner Krebs ◽  
Günther Walz ◽  
Patrick Flohr ◽  
Stefan Hoffmann
Keyword(s):  
Gas Turbine ◽  
Operating Conditions ◽  
Mode Shapes ◽  
Stable Operation ◽  
Detailed Knowledge ◽  
Test Bed ◽  
Numerical Predictions ◽  
Annular Combustor ◽  
Response Method ◽  
Compact Design

For the development of modern Low-NOx gas turbine combustors featuring high power densities due to their compact design a detailed knowledge about thermoacoustically induced combustion oscillations is required. In order to design passive and active means to suppress thermoacoustic oscillations and to extend the stable operation range of the gas turbine an investigation of the acoustic eigenmodes of the combustor already in the design phase is necessary. In a combined experimental and computational project, tools to determine the mode shapes of a gas turbine combustor have been developed. The mode shapes of an annular combustor of the 3A series have been identified under operating conditions in the test bed of Berlin by cross correlating pressure signals mounted on twelve different azimuthal locations. These data have been used in order to validate the new numerical steady state response method. It has been found that taking into account appropriate acoustic boundary conditions at the burner outlet the numerical predictions are in good agreement with the measurements.

Erfahrung ohne Erfahrenden

2009 ◽  
Vol 2009 (1) ◽  
pp. 61-78
Author(s):  
Petr Kouba
Keyword(s):  
Phenomenological Approach ◽  
Work Of Art ◽  
New Beginning ◽  
Individual Structure ◽  
The World ◽  
Il Y A ◽  
Individual Existence ◽  
The Moment ◽  
The Individual ◽  
Intentional Structure

This article examines the limits of Heidegger’s ontological description of emotionality from the period of Sein und Zeit and Die Grundbegriffe der Metaphysik along the lines outlined by Lévinas in his early work De l’existence à l’existant. On the basis of the Lévinassian concept of “il y a”, we attempt to map the sphere of the impersonal existence situated out of the structured context of the world. However the worldless facticity without individuality marks the limits of the phenomenological approach to human existence and its emotionality, it also opens a new view on the beginning and ending of the individual existence. The whole structure of the individual existence in its contingency and finitude appears here in a new light, which applies also to the temporal conditions of existence. Yet, this is not to say that Heidegger should be simply replaced by Lévinas. As shows an examination of the work of art, to which brings us our reading of Moravia’s literary exposition of boredom (the phenomenon closely examined in Die Grundbegriffe der Metaphysik), the view on the work of art that is entirely based on the anonymous and worldless facticity of il y a must be extended and complemented by the moment in which a new world and a new individual structure of experience are being born. To comprehend the dynamism of the work of art in its fullness, it is necessary to see it not only as an ending of the world and the correlative intentional structure of the individual existence, but also as their new beginning.

Monkey on My Back. An Autoethnographic Narrative of a Therapeutic Experience

2020 ◽  
Author(s):  
Adam Wiesner
Keyword(s):  
Personal Experience ◽  
Meaning Making ◽  
The Self ◽  
Symbolic Language ◽  
Discursive Practices ◽  
Therapeutic Experience ◽  
Postmodern Philosophy ◽  
The Moment ◽  
The Individual ◽  
Global Uncertainty

With a conscious attempt to contribute to contemporary discussions in mad/trans/queer/monster studies, the monograph approaches complex postmodern theories and contextualizes them from an autoethnographic methodological perspective. As the self-explanatory subtitle reads, the book introduces several topics as revelatory fields for the author’s self-exploration at the moment of an intense epistemological and ontological crisis. Reflexively written, it does not solely focus on a personal experience, as it also aims at bridging the gap between the individual and the collective in times of global uncertainty. There are no solid outcomes defined; nevertheless, the narrative points to a certain—more fluid—way out. Through introducing alternative ways of hermeneutics and meaning-making, the book offers a synthesis of postmodern philosophy and therapy, evolutionary astrology as a symbolic language, embodied inquiry, and Buddhist thought that together represent a critical attempt to challenge the pathologizing discursive practices of modern disciplines during the neoliberal capitalist era.

scholarly journals Spatially Resolved Experimental Modal Analysis on High-Speed Composite Rotors Using a Non-Contact, Non-Rotating Sensor

Sensors ◽  
2021 ◽  
Vol 21 (14) ◽  
pp. 4705
Author(s):  
Julian Lich ◽  
Tino Wollmann ◽  
Angelos Filippatos ◽  
Maik Gude ◽  
Juergen Czarske ◽  
...  
Keyword(s):  
High Speed ◽  
Natural Frequencies ◽  
Mode Shapes ◽  
Fiber Reinforced ◽  
Structural Dynamic ◽  
Spatially Resolved ◽  
Glass Fiber Reinforced ◽  
Vibration Responses ◽  
And Performance

Due to their lightweight properties, fiber-reinforced composites are well suited for large and fast rotating structures, such as fan blades in turbomachines. To investigate rotor safety and performance, in situ measurements of the structural dynamic behaviour must be performed during rotating conditions. An approach to measuring spatially resolved vibration responses of a rotating structure with a non-contact, non-rotating sensor is investigated here. The resulting spectra can be assigned to specific locations on the structure and have similar properties to the spectra measured with co-rotating sensors, such as strain gauges. The sampling frequency is increased by performing consecutive measurements with a constant excitation function and varying time delays. The method allows for a paradigm shift to unambiguous identification of natural frequencies and mode shapes with arbitrary rotor shapes and excitation functions without the need for co-rotating sensors. Deflection measurements on a glass fiber-reinforced polymer disk were performed with a diffraction grating-based sensor system at 40 measurement points with an uncertainty below 15 μrad and a commercial triangulation sensor at 200 measurement points at surface speeds up to 300 m/s. A rotation-induced increase of two natural frequencies was measured, and their mode shapes were derived at the corresponding rotational speeds. A strain gauge was used for validation.

scholarly journals Selected In Situ Hybridization Methods: Principles and Application

Molecules ◽  
2021 ◽  
Vol 26 (13) ◽  
pp. 3874
Author(s):  
Dominika Veselinyová ◽  
Jana Mašlanková ◽  
Katarina Kalinová ◽  
Helena Mičková ◽  
Mária Mareková ◽  
...  
Keyword(s):  
In Situ Hybridization ◽  
Imaging Techniques ◽  
Cell Communication ◽  
Probe Design ◽  
Rapid Progress ◽  
In Situ Techniques ◽  
Different Types ◽  
Laboratory Procedures ◽  
The Individual

We are experiencing rapid progress in all types of imaging techniques used in the detection of various numbers and types of mutation. In situ hybridization (ISH) is the primary technique for the discovery of mutation agents, which are presented in a variety of cells. The ability of DNA to complementary bind is one of the main principles in every method used in ISH. From the first use of in situ techniques, scientists paid attention to the improvement of the probe design and detection, to enhance the fluorescent signal intensity and inhibition of cross-hybrid presence. This article discusses the individual types and modifications, and is focused on explaining the principles and limitations of ISH division on different types of probes. The article describes a design of probes for individual types of in situ hybridization (ISH), as well as the gradual combination of several laboratory procedures to achieve the highest possible sensitivity and to prevent undesirable events accompanying hybridization. The article also informs about applications of the methodology, in practice and in research, to detect cell to cell communication and principles of gene silencing, process of oncogenesis, and many other unknown processes taking place in organisms at the DNA/RNA level.

Automated sequencing batch bioreactor under extreme peaks of 4-chlorophenol

2003 ◽  
Vol 47 (10) ◽  
pp. 175-181 ◽  
Author(s):  
G. Buitrón ◽  
M.-E. Schoeb ◽  
J. Moreno
Keyword(s):  
Dissolved Oxygen ◽  
Metabolic Activity ◽  
Automated System ◽  
Stable Operation ◽  
High Concentration ◽  
Batch Bioreactor ◽  
On Line ◽  
The Moment ◽  
And Control ◽  
System Operating

The operation of a sequencing batch bioreactor is evaluated when high concentration peaks of a toxic compound (4-chlorophenol, 4CP) are introduced into the reactor. A control strategy based on the dissolved oxygen concentration, measured on line, is utilized. To detect the end of the reaction period, the automated system search for the moment when the dissolved oxygen has passed by a minimum, as a consequence of the metabolic activity of the microorganisms and right after to a maximum due to the saturation of the water (similar to the self-cycling fermentation, SCF, strategy). The dissolved oxygen signal was sent to a personal computer via data acquisition and control using MATLAB and the SIMULINK package. The system operating under the automated strategy presented a stable operation when the acclimated microorganisms (to an initial concentration of 350 mg 4CP/L), were exposed to a punctual concentration peaks of 600 mg 4CP/L. The 4CP concentrations peaks superior or equals to 1,050 mg/L only disturbed the system from a short to a medium term (one month). The 1,400 mg/L peak caused a shutdown in the metabolic activity of the microorganisms that led to the reactor failure. The biomass acclimated with the SCF strategy can partially support the variations of the toxic influent since, at the moment in which the influent become inhibitory, there is a failure of the system.

Study of transient heating using an in situ combustion system

2017 ◽  
Vol 114 ◽  
pp. 685-692
Author(s):  
Fabián E. Cano Ardila ◽  
Andrés A. Amell Arrieta
Keyword(s):  
Combustion System ◽  
Transient Heating ◽  
In Situ Combustion

The Effect of Homoeologous Meiotic Pairing in Tetraploid Hordeum bulbosum L. × H. vulgare L. Hybrids on Alien Introgressions in Offspring

2016 ◽  
Vol 150 (2) ◽  
pp. 139-149 ◽  
Author(s):  
Margret Scholz ◽  
Galina Pendinen
Keyword(s):  
Interspecific Hybrids ◽  
In Situ Hybridisation ◽  
Basic Material ◽  
Meiotic Pairing ◽  
Hordeum Bulbosum ◽  
Homoeologous Pairing ◽  
Introgression Breeding ◽  
The Individual ◽  
Pairing Behaviour

The pairing behaviour of the individual chromosome arms of Hordeum vulgare (Hv) with their homoeologous arms of H. bulbosum (Hb) at metaphase I of meiosis in tetraploid Hb × Hv hybrids and the frequencies of recombined Hv chromosome arms in selfed offspring were studied on differentially visualized chromosomes after fluorescent in situ hybridisation. The frequencies of paired Hv-Hb arms in the F2 and F3 hybrids were correlated with the frequencies of recombined Hv chromosomes in progenies. Self-generation of hybrids, the number of Hv and Hb chromosomes, and the number of recombined Hv chromosomes of the hybrids strongly influenced the Hv-Hb pairing frequency in meiosis. Within the offspring of F2 and F3 hybrids both Hv plants and hybrids were detected. In contrast, all progenies of the F4 hybrid were hybrids which exhibited centromere misdivisions. The highest frequencies of homoeologous pairing in hybrids and most recombinants were obtained for the barley chromosome 1HL. Recombinants for 4HL, 5HS, 6HS, and 7HS were rarely found. Meiotic pairing and recombinants involving chromosome 1HS were never observed. The results of this study demonstrate that fertile tetraploid interspecific hybrids with a high intergenomic pairing at meiosis are valuable basic material for introgression breeding in barley.

scholarly journals Chromatin fibers observed in situ in frozen hydrated sections. Native fiber diameter is not correlated with nucleosome repeat length.

1994 ◽  
Vol 125 (1) ◽  
pp. 11-19 ◽  
Author(s):  
C L Woodcock
Keyword(s):  
Cell Types ◽  
Repeat Length ◽  
Strong Positive Correlation ◽  
Whole Cells ◽  
Chromosome Architecture ◽  
Chromatin Fibers ◽  
The Moment ◽  
Chicken Erythrocytes ◽  
Patiria Miniata

Chromatin fibers have been observed and measured in frozen hydrated sections of three types of cell (chicken erythrocytes and sperm of Patiria miniata and Thyone briareus) representing an approximately 20-bp range of nucleosomal repeat lengths. For sperm of the starfish P. miniata, it was possible to obtain images of chromatin fibers from cells that were swimming in seawater up to the moment of cryo-immobilization, thus providing a record of the native morphology of the chromatin of these cells. Glutaraldehyde fixation produced no significant changes in the ultrastructure or diameter of chromatin fibers, and fiber diameters observed in cryosections were similar to those recorded after low temperature embedding in Lowicryl K11M. Chromatin fiber diameters measured from cryosections of the three types of nuclei were similar, a striking contrast to the situation for chromatin isolated from these cell types, where a strong positive correlation between diameter and nucleosomal repeat length has been established. The demonstration of chromatin fibers in unfixed whole cells establishes an unequivocal baseline for the study of native chromatin and chromosome architecture. The significant differences between chromatin fibers in nucleo and after isolation supports a previous observation (P. J. Giannasca, R. A. Horowitz, and C. L. Woodcock. 1993. J. Cell Sci. 105:551-561), and suggests that structural studies on isolated material should be interpreted with caution until the changes that accompany chromatin isolation are understood.

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