Relevant bibliographies by topics / Helmholtz Model

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Academic literature on the topic 'Helmholtz Model'

Author: Grafiati
Published: 6 September 2023

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Journal articles on the topic "Helmholtz Model"

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Tang, H., and S. Zhong. "A static compressible flow model of synthetic jet actuators." Aeronautical Journal 111, no. 1121 (July 2007): 421–31. http://dx.doi.org/10.1017/s0001924000004681.

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Abstract In this paper, a simple static compressible flow model for circular synthetic jet actuators is described. It is used to undertake a systematic computational investigation of the effect of changing actuator geometrical and operating parameters on the magnitude of peak jet velocity at the orifice exit of an actuator whose diaphragm displacement and frequency are allowed to vary independently. It is found that, depending on the flow conditions inside the orifice duct, the actuator may operate in two distinct regimes, i.e. the Helmholtz resonance regime and the viscous flow regime. In the Helmholtz resonance regime, the resultant synthetic jet is generated by the mass physically displaced by the oscillating diaphragm coupled with the Helmholtz resonance in the actuator. In the viscous flow regime, the Helmholtz resonance is completely damped by viscous effect such that the jet is produced by the diaphragm oscillation alone. The relationship between actuator geometrical and operating parameters at the optimum condition which yields the maximum peak jet velocity at a given diaphragm displacement is also established for these two regimes. Finally, a preliminary procedure for designing synthetic jet actuators for flow separation control on an aircraft wing is proposed.
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Liu, Xin, Yuanyu Yu, Jiujiang Wang, Sio Hang Pun, Mang I. Vai, and Peng Un Mak. "An Analytical Model for Bandwidth Enhancement of Air-Coupled Unsealed Helmholtz Structural CMUTs." Journal of Sensors 2019 (April 17, 2019): 1–16. http://dx.doi.org/10.1155/2019/3896965.

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Capacitive micromachined ultrasonic transducers (CMUTs) were reported to own high potential in air-coupled ultrasonic applications such as noncontact nondestructive examination and gas flow measurement. The unsealed CMUTs which utilized the squeeze film effect were reported to overcome the narrow output pressure bandwidth of the conventional sealed CMUTs in air operation. This kind of unsealed CMUTs can also be regarded as Helmholtz resonators. In this work, we present the air-coupled unsealed Helmholtz structural CMUTs which utilize both the squeeze film effect and the Helmholtz resonant effect to enhance the output pressure bandwidth. Based on the mechanism of vibration coupling between membrane and air pistons in membrane holes, we propose an analytical model to aid the design process of this kind of CMUTs. We also use finite element method (FEM) to investigate this kind of CMUTs for our analytical model validation. The FEM results show that the significant bandwidth enhancement can be achieved when the Helmholtz resonant frequency is designed close to the fundamental resonant frequency of the CMUT membrane. Compared with the conventional sealed CMUT cell, the 4-hole unsealed Helmholtz structural CMUT cell improves both the 3-dB fractional bandwidth and SPL-bandwidth product around 35 times. Furthermore, it is found that, with more holes under the same hole area ratio or with a smaller ratio of the cavity height to the viscous boundary layer thickness, the Helmholtz resonant effect becomes weaker and thus the output pressure bandwidth decreases.
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Sosnov, Valeriy. "Analysis of Control Problems for 2-D Model of Sound Scattering." Applied Mechanics and Materials 770 (June 2015): 531–34. http://dx.doi.org/10.4028/www.scientific.net/amm.770.531.

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In this paper control problems for 2-D Helmholtz equation are formulated and investigated. These problems are associated with developing technology of acoustic cloaking. Helmholtz equation is considered in an unbounded domain with the impedance boundary condition. The role of control in control problems under study is played by surface impedance.
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Feng, Guo-Hua, and Wen-Sheng Chen. "Piezoelectric Micromachined Ultrasonic Transducer-Integrated Helmholtz Resonator with Microliter-Sized Volume-Tunable Cavity." Sensors 22, no. 19 (October 2, 2022): 7471. http://dx.doi.org/10.3390/s22197471.

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In this study, a piezoelectric micromachined ultrasonic transducer (PMUT) is integrated with a microliter-sized volume-tunable Helmholtz resonator. The passive Helmholtz resonator is constructed using an SU8 photolithography-defined square opening plate as the neck portion, a 3D-printed hollow structure with a threaded insert nut, and a precision set screw to form the volume-controllable cavity of the Helmholtz resonator. The fabricated piezoelectric films acted as ultrasonic actuators attached to the surface of the neck SU8 plate. Experimental results show that the sound pressure level (SPL) and operation bandwidth could be effectively tuned, and a 200% SPL increase and twofold bandwidth enhancement are achieved when setting the cavity length to 0.75 mm compared with the open-cavity case. A modified Helmholtz resonator model is proposed to explain the experimental results. The adjusting factors of the effective mass and viscous damper are created to modify the existing parameters in the conventional Helmholtz resonator model. The relationship between the adjusting factors and cavity length can be described well using a two-term power series curve. This modified Helmholtz resonator model not only provides insight into this active-type Helmholtz resonator operation but also provides a useful estimation for its optimal design and fabrication.
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Dayan, Peter, Geoffrey E. Hinton, Radford M. Neal, and Richard S. Zemel. "The Helmholtz Machine." Neural Computation 7, no. 5 (September 1995): 889–904. http://dx.doi.org/10.1162/neco.1995.7.5.889.

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Discovering the structure inherent in a set of patterns is a fundamental aim of statistical inference or learning. One fruitful approach is to build a parameterized stochastic generative model, independent draws from which are likely to produce the patterns. For all but the simplest generative models, each pattern can be generated in exponentially many ways. It is thus intractable to adjust the parameters to maximize the probability of the observed patterns. We describe a way of finessing this combinatorial explosion by maximizing an easily computed lower bound on the probability of the observations. Our method can be viewed as a form of hierarchical self-supervised learning that may relate to the function of bottom-up and top-down cortical processing pathways.
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Megasari, M. "Dual Reciprocity Boundary Element Method untuk Menyelesaikan Masalah Infiltrasi Stasioner pada Saluran Datar Periodik." Journal of Mathematics Computations and Statistics 4, no. 1 (May 1, 2021): 30. http://dx.doi.org/10.35580/jmathcos.v4i1.20447.

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Abstrak. Penelitian ini membahas tentang penyelesaian masalah infiltrasi stasioner dari saluran datar dengan Dual Reciprocity Boundary Element Method (DRBEM). Persamaan pembangun untuk masalah ini adalah persamaan Richard. Menggunakan transformasi Kirchhoff dan relasi eksponensial konduktifitas hidrolik, persamaan Richard ditransformasi ke dalam persamaan infiltrasi stasioner dalam Matric Flux Potential (MFP). Persamaan infiltrasi dalam MFP selanjutnya diubah ke dalam persamaan Helmholtz termodifikasi. Model matematika infiltrasi stasioner pada saluran datar berbentuk Masalah Syarat batas Helmholtz termodifikasi Solusi numerik diperoleh dengan menyelesaikan persamaan Helmholtz termodifikasi menggunakan Dual Reciprocity Boundary Element Method (DRBEM) dengan pengambilan jumlah titik kolokasi eksterior dan interior yang bervariasi. Lebih lanjut, solusi numerik dan solusi analitik dibandingkan..Kata Kunci: Infiltrasi, saluran datar, persamaan helmholtz termodifikasi, DRBEM.Abstract. This research discusses about the problem solving of steady infiltration problem from flat channel with Dual Reciprocity Boundary Element Method (DRBEM). The governing equation for this problem is Richard’s equation. Using Kirchhoff transformation and exponential hydraulic conductivity relation, Richard’s equation is transformed into steady infiltration equation in the form of MFP. Infiltration equation in the form of MFP is then transformed to modified Helmholtz equation. A mathematical model of steady infiltration from flat channel in the form of boundary condition problem of modified Helmholtz EQUATION. Numerical solution is obtained by solving modified Helmholtz equation by using Dual Reciprocity Boundary Element Method (DRBEM) with various number of exterior and interior collocation points. Moreover, numerical and analytic solution are then compared.Keywords: infiltration, flat channel, modified Helmholtz equation, DRBEM
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Wang, Jianguo, Philip Rubini, Qin Qin, and Brian Houston. "A Model to Predict Acoustic Resonant Frequencies of Distributed Helmholtz Resonators on Gas Turbine Engines." Applied Sciences 9, no. 7 (April 4, 2019): 1419. http://dx.doi.org/10.3390/app9071419.

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Helmholtz resonators, traditionally designed as a narrow neck backed by a cavity, are widely applied to attenuate combustion instabilities in gas turbine engines. The use of multiple small holes with an equivalent open area to that of a single neck has been found to be able to significantly improve the noise damping bandwidth. This type of resonator is often referred to as “distributed Helmholtz resonator”. When multiple holes are employed, interactions between acoustic radiations from neighboring holes changes the resonance frequency of the resonator. In this work, the resonance frequencies from a series of distributed Helmholtz resonators were obtained via a series of highly resolved computational fluid dynamics simulations. A regression analysis of the resulting response surface was undertaken and validated by comparison with experimental results for a series of eighteen absorbers with geometries typically employed in gas turbine combustors. The resulting model demonstrates that the acoustic end correction length for perforations is closely related to the effective porosity of the perforated plate and will be obviously enhanced by acoustic radiation effect from the perforation area as a whole. This model is easily applicable for engineers in the design of practical distributed Helmholtz resonators.
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Matveev, Konstantin I. "Thermoacoustically controlled Helmholtz resonators." Proceedings of the Institution of Mechanical Engineers, Part C: Journal of Mechanical Engineering Science 227, no. 11 (February 15, 2013): 2563–68. http://dx.doi.org/10.1177/0954406213477569.

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Helmholtz resonators and their modifications are commonly applied for suppressing unwanted sound, including acoustic oscillations in chambers of propulsion and power systems. Sound absorption characteristics of Helmholtz resonators can be enhanced and controlled with a use of thermal stratification in porous insets inside resonators. A simplified lumped-element model for thermoacoustically augmented Helmholtz resonators is developed in this article. Sample calculations illustrate effects of temperature gradients, porosity, positions of porous insets, and locations of resonators inside chambers.
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Hersh, A. S., B. E. Walker, and J. W. Celano. "Helmholtz Resonator Impedance Model, Part 1: Nonlinear Behavior." AIAA Journal 41, no. 5 (May 2003): 795–808. http://dx.doi.org/10.2514/2.2041.

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El-Sayed, Salah M., and Doǧan Kaya. "Comparing numerical methods for Helmholtz equation model problem." Applied Mathematics and Computation 150, no. 3 (March 2004): 763–73. http://dx.doi.org/10.1016/s0096-3003(03)00305-9.

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Dissertations / Theses on the topic "Helmholtz Model"

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Scheiman, Kevin S. "A Parallel Spectral Method Approach to Model Plasma Instabilities." Wright State University / OhioLINK, 2018. http://rave.ohiolink.edu/etdc/view?acc_num=wright1527424992108785.

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Liu, Bing. "Properties Model for Aqueous Sodium Chloride Solutions near the Critical Point of Water." Diss., CLICK HERE for online access, 2005. http://contentdm.lib.byu.edu/ETD/image/etd1034.pdf.

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Gernert, Georg Johannes [Verfasser], Roland [Gutachter] Span, and Eckhard [Gutachter] Weidner. "A new Helmholtz energy model for humid gases and CCS mixtures / Georg Johannes Gernert ; Gutachter: Roland Span, Eckhard Weidner ; Fakultät für Maschinenbau." Bochum : Ruhr-Universität Bochum, 2013. http://d-nb.info/1212661400/34.

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Völker, Doris [Verfasser]. "Chemical-sensitive genes in zebrafish (Danio rerio) early development - identification and characterisation of differential expression in embryos exposed to the model compound 3,4-dichloroaniline / Doris Völker. [Helmholtz Centre for Environmental Research, UFZ]." Leipzig : Helmholtz Centre for Environmental Research, 2007. http://d-nb.info/1007282541/34.

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Sargent, Cristina Vasilica. "Trapped modes of the Helmholtz equation." Thesis, Imperial College London, 2013. http://hdl.handle.net/10044/1/11115.

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In the framework of the classical theory of linearised water waves in unbounded domains, trapped modes consist of non-propagating, localised oscillation modes of finite energy occurring at some well-defined frequency and which, in the absence of dissipation, persist in time even in the absence of external forcing. Jones (1953) proved the existence of trapped modes for problems governed by the Helmholtz equation in semi-infinite domains. Trapped modes have been studied in quantum mechanics, elasticity and acoustics and are known, depending on the context, as bound states, acoustic resonances, Rayleigh-Bloch waves, sloshing modes and motion trapped modes. We consider trapped modes in two dimensional infinite waveguides with either Neumann or Dirichlet boundary conditions. Such problems arise when considering obstacles in acoustic waveguides or bound states in quantum wires for example. The mathematical model is a boundary value problem for the Helmholtz equation. Under the usual assumptions of potential theory, the solution is written in terms of a boundary integral equation. We develop a Boundary Element Method (BEM) program which we use to obtain approximate numerical solutions. We extend existing results by identifying additional trapped modes for geometries already studied and investigate new structures. We also carry out a detailed investigation of trapped modes, using the planewave spectrum representation developed for various characteristic problems from the classical theories of radiation, diffraction and propagation. We use simple planewaves travelling in diverse directions to build a more elaborate solution, which satisfies certain conditions required for a trapped mode. Our approach is fairly flexible so that the general procedure is independent of the shape of the trapping obstacle and could be adapted to other geometries. We apply this method to the case of a disc on the centreline of an infinite Dirichlet acoustic waveguide and obtain a simple mathematical approximation of a trapped mode, which satisfies a set of criteria characteristic of trapped modes. Asymptotically, the solution obtained is similar to a nearly trapped mode, which is a perturbation of a genuine trapped mode.
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Liu, Guanhui. "Formulation of multifield finite element models for Helmholtz problems." Click to view the E-thesis via HKUTO, 2010. http://sunzi.lib.hku.hk/hkuto/record/B44204875.

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Liu, Guanhui, and 刘冠辉. "Formulation of multifield finite element models for Helmholtzproblems." Thesis, The University of Hong Kong (Pokfulam, Hong Kong), 2010. http://hub.hku.hk/bib/B44204875.

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FANTI, ALESSANDRO. "A generalized finite difference approach to the computation of modes." Doctoral thesis, Università degli Studi di Cagliari, 2012. http://hdl.handle.net/11584/266145.

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This thesis deals with numerical techniques for the computation of modes in electromagnetic structures with arbitrary geometry. The approach proposed in this work is based on the Finite Difference (FD) and Vector Finite Difference (VFD), which are applied to rectangular, circular, elliptical geometries, and to combination of them. The FD is applied using a 2D cartesian, polar and elliptical grid in the waveguide section. A suitable Taylor expansion of the mode function allows, either for scalar and for vector FD, to take exactly into account the boundary condition. To prevent the raising of spurious modes, the VFD approximation results in a constrained eigenvalue problem, that has been solved using a decomposition method. All approaches presented have been validated comparing the results to the analytical modes of rectangular and circular waveguide, and to known data for the elliptic case. The standard calculation of the waveguide modes using FD requires the use of two different grids, namely one for TE modes and the other for TM modes, due to the different boundary condition. It has been shown that a single grid can be used for all modes, thus allowing an effective mode-matching solution. The FD approach has been extended to waveguides (and apertures) with irregular boundaries, and therefore non-regular discretization grids. It has been shown that a suitable FD approximation of the Laplace operator is still possible. A ridged-waveguide, with trapezoidal ridges, and a rounded-ended waveguide have been considered in detail.
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Faure, Cédric. "Contrôle de la diffusion par des façades : cas des métasurfaces et des guides d'ondes ouverts inhomogènes." Thesis, Le Mans, 2017. http://www.theses.fr/2017LEMA1033/document.

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L’objectif de ce travail est le développement de dispositifs de contrôle de la diffusion des ondes acoustiques à l’aide de surfaces hétérogènes, pour des applications à l’acoustique urbaine. Pour remplir cet objectif, deux méthodes sont employées. La première à l’aide d’une métasurface, la direction d’une onde réfléchie est contrôlée. La seconde étude concerne l’influence d’un traitement inhomogène aux parois d’un guide ouvert sur les effets conjoints ou compétitifs d’absorption, de confinement et de rayonnement de l’onde. Nous montrons expérimentalement la possibilité de dissimuler un objet disposé sur un mur pour une onde acoustique audible. Pour y parvenir, une métasurface composée de différents résonateurs de Helmholtz est conçue et est réalisée de façon à être la plus fine possible. Ces travaux sont réalisés dans le domaine fréquentiel mais également dans le domaine temporel, ce qui permet de mettre en avant le caractère large bande de la métasurface. Il est démontré numériquement et expérimentalement que la direction des ondes réfléchies peut être contrôlée. Enfin la dernière partie est consacrée à l’influence d’une paroi hétérogène sur la propagation d’une onde acoustique à l’intérieur d’une rue. Une rue pouvant être assimilée à un guide d’onde ouvert engendre donc des modes de propagation complexes, dus aux pertes par rayonnement. La présence d’un matériau poreux sur les parois d’un guide vient perturber fortement la localisation spatiale des modes, ce qui les rend plus ou moins fuyants
The aim of this thesis is to develop a scheme for controling the propagation of acoustic waves using heteregenous surfaces. Its results can be applied in the field of urban acoustic. The thesis is composed of two sections, each of them employing a different method. The first section focuses on controling the direction of a reflected wave, using a metasurface. The second concentrates on the influence of an inconsistent treatment to the side of an open waveguide on the wave joint and competitive effects of absorption, confinement and radiation. Part one provides experimental evidence that it is possible to conceal an object placed on a wall from an audible acoustic wave. To prove it, the thinest possible metasurface was constructed with Helmholtz resonators. The experimental results were compared to a numerical study realized with finite elements. This work was made in both temporal and frequency domains, allowing to point out the wide frequency characteristics of the metasurface. The numerical and experimental results show that the direction of a reflected wave can, indeed, be controled. Part two analyse the impact of a heterogeneous wall on the spreadinf of an acoustic wave in a street. Due to radiation losses, the street produces complex ways of propagation. The presence of a porous material on a waveguide‘ side deeply disrupt the spatial location of these waves, making them more or less fleeting. In particular, depending on the position of the material in the street, certain waves will be more confined to the inside of the street, radiating less towards the open external environment. They are consequently, less cushioned
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Djoudi, Adel. "Binary level static analysis." Thesis, Université Paris-Saclay (ComUE), 2016. http://www.theses.fr/2016SACLX093.

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Les méthodes de vérification automatique des logiciels connaissent un succès croissant depuis le début des années 2000, suite à plusieurs succès industriels (Microsoft, Airbus, etc.). L'analyse statique vise, à partir d'une description du programme, à inférer automatiquement des propriétés vérifiées par celui-ci. Les techniques standards d'analyse statique travaillent sur le code source du logiciel, écrit par exemple en C ou Java. Cependant, avoir accès au code source n'est pas envisageable pour de nombreuses applications relatives à la sécurité, soit que le code source n'est pas disponible (code mobile, virus informatiques), soit que le développeur ne veut pas le divulguer (composants sur étagère, certification par un tiers).Nous nous intéressons dans cette thèse à la conception et au développement d'une plate-forme d'analyse statique de code binaire à des fins d'analyse de sécurité. Nos principales contributions se font à trois niveaux: sémantique, implémentation et analyse statique.Tout d'abord, la sémantique des programmes binaires analysés est basée sur un formalisme générique appelé DBA qui a été enrichi avec des mécanismes de spécification et d'abstraction. La définition de la sémantique des programmes binaires requiert aussi un modèle mémoire adéquat.Nous proposons un modèle mémoire adapté au binaire, inspiré des travaux récents sur le code C bas-niveau. Ce nouveau modèle permet de profiter de l'abstraction du modèle à régions tout en gardant l'expressivité du modèle plat.Ensuite, notre plate-forme d'analyse de code binaire nommée BinSec offre trois services de base: désassemblage, simulation et analyse statique.Chaque instruction machine est traduite vers un bloc d'instructions DBA avec une sémantique équivalente. Une large partie des instructions x86 est gérée par la plateforme. Une passe de simplification permet d'éliminer les calculs intermédiaires inutiles afin d'optimiser le fonctionnement des analyses ultérieures. Nos simplifications permettent notamment d'éliminer jusqu'à75% des mises à jours de flags.Enfin, nous avons développé un moteur d'analyse statique de programmes binaires basé sur l'interprétation abstraite. Outre des domaines adaptés aux spécificités du code binaire, nous nous sommes concentrés sur le contrôle par l'utilisateur du compromis entre précision/correction et efficacité. De plus, nous proposons une approche originale de reconstruction de conditions dehaut-niveau à partir des conditions bas-niveau afin de gagner plus de précision d'analyse. L'approche est sûre, efficace, indépendante de la plateforme cibleet peut atteindre des taux de reconstruction très élevés
Automatic software verification methods have seen increasing success since the early 2000s, thanks to several industrial successes (Microsoft, Airbus, etc.).Static program analysis aims to automatically infer verified properties of programs, based on their descriptions. The standard static analysis techniques apply on the software source code, written for instance in C or Java. However, access to source code is not possible for many safety-related applications, whether the source code is not available (mobile code, computer virus), or the developer does not disclose it (shelf components, third party certification).We are interested in this dissertation in design and development of a static binary analysis platform for safety analysis. Our contributions are made at three levels: semantics, implementation and static analysis.First, the semantics of analyzed binary programs is based on a generic, simple and concise formalism called DBA. It is extended with some specification and abstraction mechanisms in this dissertation. A well defined semantics of binary programs requires also an adequate memory model. We propose a new memory model adapted to binary level requirements and inspired from recent work on low-level C. This new model allows to enjoy the abstraction of the region-based memory model while keeping the expressiveness of the flat model.Second, our binary code analysis platform BinSec offers three basic services:disassembly, simulation and static analysis. Each machine instruction is translated into a block of semantically equivalent DBA instructions. The platform handles a large part of x86 instructions. A simplification step eliminates useless intermediate calculations in order to ease further analyses. Our simplifications especially allow to eliminate up to 75% of flag updates.Finally, we developed a static analysis engine for binary programs based on abstract interpretation. Besides abstract domains specifically adapted to binary analysis, we focused on the user control of trade offs between accuracy/correctness and efficiency. In addition, we offer an original approach for high-level conditions recovery from low-level conditions in order to enhance analysis precision. The approach is sound, efficient, platform-independent and it achieves very high ratio of recovery
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Books on the topic "Helmholtz Model"

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Cyklis, Piotr. Identyfikacja termodynamiczna elementó instalacji sprężarek wyporowych: Uogólnienie modelu Helmholtza. Kraków: Politechnika Krakowska, 1999.

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Stone, James M. The stability of radiatively cooling jets. [Washington, DC: National Aeronautics and Space Administration, 1997.

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Finite element analysis of acoustic scattering. New York: Springer, 1998.

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service), SpringerLink (Online, ed. Electromagnetic wave scattering on nonspherical particles: Basic methodology and simulations. Berlin: Springer, 2009.

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Kim, Yang-Hann, and Jung-Woo Choi. Sound Visualization and Manipulation. Wiley & Sons, Limited, John, 2013.

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Kim, Yang-Hann, and Jung-Woo Choi. Sound Visualization and Manipulation. Wiley & Sons, Incorporated, John, 2013.

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Kim, Yang-Hann, and Jung-Woo Choi. Sound Visualization and Manipulation. Wiley & Sons, Incorporated, John, 2013.

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Kim, Yang-Hann, and Jung-Woo Choi. Sound Visualization and Manipulation. Wiley, 2013.

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Kim, Yang-Hann, and Jung-Woo Choi. Sound Visualization and Manipulation. Wiley & Sons, Incorporated, John, 2013.

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Kim, Yang-Hann, and Jung-Woo Choi. Sound Visualization and Manipulation. Wiley & Sons, Incorporated, John, 2013.

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Book chapters on the topic "Helmholtz Model"

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Caruthers, Jerald W., Stanley A. Chin-Bing, and Jorge C. Novarini. "Statistical Characteristics of Acoustic Fields Scattered at the Sea Surface: A Helmholtz-Gulin Model." In Progress in Underwater Acoustics, 65–73. Boston, MA: Springer US, 1987. http://dx.doi.org/10.1007/978-1-4613-1871-2_9.

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dos Santos, Rodrigo Guedes, Atilio Barbosa Lourenço, Pedro Rosseto de Faria, Igor Chaves Belisario, Marcelo Aiolfi Barone, and José Joaquim C. S. Santos. "A Comparative Study of the Recent A&F Model with Conventional Thermoeconomic Methodologies in the Waste Treatment in a Regenerative Gas Turbine Cogeneration System." In Proceedings of the XV Ibero-American Congress of Mechanical Engineering, 237–43. Cham: Springer International Publishing, 2023. http://dx.doi.org/10.1007/978-3-031-38563-6_35.

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AbstractThermoeconomics is a science that reconciles thermodynamic and economic concepts. It can be divided into three fields of action: cost allocation, diagnosis and optimization. Most thermoeconomicists agree that exergy is the most appropriate thermodynamic magnitude to associate with cost. In some applications, exergy disaggregation is required. Literature shows several thermoeconomic methodologies. Despite the wide use and their respective fields of action, all models have limitations in the dissipative equipment isolation and waste treatment or an increase in complexity in thermoeconomic modeling. In order to fill part of this scientific gap in thermoeconomics, a recent methodology, the A&F Model, is proposed. This new approach disaggregates physical exergy into just two terms, namely Helmholtz energy and flow work. This work presents for the first time the use of this new approach, through a cost allocation, in a cogeneration system with regenerative gas turbine, and compares it with conventional thermoeconomic methodologies.
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Garrett, Steven L. "Dissipative Hydrodynamics." In Understanding Acoustics, 421–52. Cham: Springer International Publishing, 2020. http://dx.doi.org/10.1007/978-3-030-44787-8_9.

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Abstract In the previous chapter, the resonance frequency, ωo, of a Helmholtz resonator was calculated. When driven at that frequency, the predicted pressure amplitude inside the resonator’s volume (compliance) became infinite. This was because the theory used to model that inertance and compliance network in Figs. 10.1007/978-3-030-44787-8_8#Fig11 and 10.1007/978-3-030-44787-8_8#Fig15, and in Eq. (10.1007/978-3-030-44787-8_8#Equ50), did not include any dissipation. By introducing DeltaEC, we were able to calculate the amount of power dissipated in the neck (inertance) and volume (compliance) of a 500 ml boiling flask. In this chapter, those losses will be calculated from hydrodynamic “first principles.”
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LePage, Eric L. "Helmholtz Revisited: Direct Mechanical Data Suggest a Physical Model for Dynamic Control of Mapping Frequency to Place Along the Cochlear Partition." In Lecture Notes in Biomathematics, 278–87. New York, NY: Springer New York, 1990. http://dx.doi.org/10.1007/978-1-4757-4341-8_34.

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Garrett, Steven L. "Nondissipative Lumped Elements." In Understanding Acoustics, 357–419. Cham: Springer International Publishing, 2020. http://dx.doi.org/10.1007/978-3-030-44787-8_8.

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Abstract The goal of this chapter is to start applying the laws of hydrodynamics to acoustics. By applying these laws to some simple acoustical networks, we can begin to develop our understanding of their meaning, as well as exploit their broad utility. We start by ignoring dissipation and by choosing acoustical elements that are small compared to the wavelength of sound. In this nondissipative lumped-element approximation, the continuity equation leads us to the definition of an acoustical compliance (or gas stiffness) that plays the same role as a capacitor in alternating current (AC) electrical circuit theory or a spring in the theory of mechanical vibrations. Under those same approximations, the Euler equation leads to the definition of an acoustical inertance, which is equivalent to an inductor in the electrical analogy, or a mass in the theory of mechanical vibrations. The combination of an acoustical inertance and acoustical compliance is called a Helmholtz resonator. The DeltaEC software is introduced to model such acoustical networks. Because DeltaEC includes dissipation, it provides benchmark results that can be compared to the calculations based on dissipative hydrodynamics in the following chapter.
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Naidoo, P., D. Ramjugernath, K. Moodley, and T. M. Letcher. "CHAPTER 8. Correlative and Predictive Models for GE." In Gibbs Energy and Helmholtz Energy, 269–98. Cambridge: Royal Society of Chemistry, 2021. http://dx.doi.org/10.1039/9781839164095-00269.

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Michelitsch, T. M., J. Wang, H. Gao, and V. M. Levin. "On the Solutions of the Inhomogeneous Helmholtz Wave Equation for Ellipsoidal Sources." In Continuum Models and Discrete Systems, 115–22. Dordrecht: Springer Netherlands, 2004. http://dx.doi.org/10.1007/978-1-4020-2316-3_19.

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Becciu, Alessandro, Remco Duits, Bart J. Janssen, Luc M. J. Florack, and Hans C. van Assen. "Cardiac Motion Estimation Using Covariant Derivatives and Helmholtz Decomposition." In Statistical Atlases and Computational Models of the Heart. Imaging and Modelling Challenges, 263–73. Berlin, Heidelberg: Springer Berlin Heidelberg, 2012. http://dx.doi.org/10.1007/978-3-642-28326-0_27.

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Stone, James M. "Asymmetric Modes of the Kelvin-Helmholtz Instability in Protostellar Jets." In Herbig-Haro Flows and the Birth of Low Mass Stars, 323–33. Dordrecht: Springer Netherlands, 1997. http://dx.doi.org/10.1007/978-94-011-5608-0_26.

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Lannes, David, and Mei Ming. "The Kelvin-Helmholtz Instabilities in Two-Fluids Shallow Water Models." In Hamiltonian Partial Differential Equations and Applications, 185–234. New York, NY: Springer New York, 2015. http://dx.doi.org/10.1007/978-1-4939-2950-4_7.

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Conference papers on the topic "Helmholtz Model"

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Celano, J., A. Hersh, and B. Walker. "Semi-empirical Helmholtz resonator impedance model." In 5th AIAA/CEAS Aeroacoustics Conference and Exhibit. Reston, Virigina: American Institute of Aeronautics and Astronautics, 1999. http://dx.doi.org/10.2514/6.1999-1825.

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Regan, Basil, and John Eaton. "Finite element micro-model of Helmholtz liner configuration." In 4th AIAA/CEAS Aeroacoustics Conference. Reston, Virigina: American Institute of Aeronautics and Astronautics, 1998. http://dx.doi.org/10.2514/6.1998-2312.

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Rienstra, Sjoerd. "Impedance Models in Time Domain, Including the Extended Helmholtz Resonator Model." In 12th AIAA/CEAS Aeroacoustics Conference (27th AIAA Aeroacoustics Conference). Reston, Virigina: American Institute of Aeronautics and Astronautics, 2006. http://dx.doi.org/10.2514/6.2006-2686.

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Zhang, Man, Yuzhen Lin, and Wenjie Tao. "Analytical Study of Low-Frequency Helmholtz Mode Oscillation in a Model Combustor." In ASME Turbo Expo 2017: Turbomachinery Technical Conference and Exposition. American Society of Mechanical Engineers, 2017. http://dx.doi.org/10.1115/gt2017-64130.

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The “growl” mode combustion instability is one of the most destructive phenomenon occurring in the lean burn aeroengine combustor at low power condition. This topic is widely investigated these years focusing on the mechanism of flame structures, oscillation modes and the development of prediction methods. Recently, an analytical prediction method which based on the linear solution of Helmholtz equation was successfully used to predict the inception of the growl instability. In this model, the flame tube and the inflow duct are modeled as individual cavities and connected through a swirler acting as the neck of Helmholtz resonators. However, in many applications, the inflow duct has more complex geometry and thus complex acoustic boundary condition. So there is the need to extend this approach in a more universal form. This is the motivation of the current work. This paper firstly presents the measured dynamic pressure and the flame motions in a single sector combustor. By changing the cross section area of the inflow duct, self-excited combustion instability was observed. This combustion instability mainly occurred at the frequency of 350HZ∼400Hz. The test results showed that flame front moves with the bulk flow in the axial direction while the pressure fluctuations in the inflow duct show a harmonic feature. It confirms that the combustion instability corresponds to the Helmholtz mode. This phenomenon was next analyzed with a new low-order linear acoustic method developed in this paper. The method integrates the model of Helmholtz resonator within harmonic oscillation (also called IM2H), and is validated by comparing with experimental data. By considering Helmholtz oscillation in the flame tube, the predicted frequency and mode agree well with experiments. The results show that the stability of the system is more sensitive to the geometry design parameter than the aerodynamics parameters.
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Radin, Danila, Georgy Makaryants, and Dmitriy Borisov. "Mathematical model and dynamic characteristics of Helmholtz resonator cavity." In 2020 International Conference on Dynamics and Vibroacoustics of Machines (DVM). IEEE, 2020. http://dx.doi.org/10.1109/dvm49764.2020.9243888.

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Sereda, S. N., V. V. Bulkin, M. V. Kalinichenko, and P. M. Guskov. "Mathematical model of acoustic baffle based on helmholtz resonator." In 2017 Dynamics of Systems, Mechanisms and Machines (Dynamics). IEEE, 2017. http://dx.doi.org/10.1109/dynamics.2017.8239504.

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Lu, Wangtao, Jianliang Qian*, and Robert Burridge. "Babich-expansion based Fast Huygens Sweeping Methods for Point-source Helmholtz Equations." In 2015 Workshop: Depth Model Building: Full-waveform Inversion, Beijing, China, 18-19 June 2015. Society of Exploration Geophysicists, 2015. http://dx.doi.org/10.1190/fwi2015-024.

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Singh, Deepesh K., and Sjoerd W. Rienstra. "A systematic impedance model for non-linear Helmholtz resonator liner." In 19th AIAA/CEAS Aeroacoustics Conference. Reston, Virginia: American Institute of Aeronautics and Astronautics, 2013. http://dx.doi.org/10.2514/6.2013-2223.

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Rienstra, Sjoerd W., and Deepesh Kumar Singh. "An asymptotic model for non-linear Helmholtz resonator of finite depth." In 22nd AIAA/CEAS Aeroacoustics Conference. Reston, Virginia: American Institute of Aeronautics and Astronautics, 2016. http://dx.doi.org/10.2514/6.2016-2887.

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Rivero, L. "Approach Model of Speech Production Using Helmholtz Resonator and Wave Equation." In 2010 European Modelling Symposium (EMS). IEEE, 2010. http://dx.doi.org/10.1109/ems.2010.102.

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Reports on the topic "Helmholtz Model"

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Schneider, M. Bayesian Model Selection as a Continuous-Variable Helmholtz Machine. Office of Scientific and Technical Information (OSTI), August 2020. http://dx.doi.org/10.2172/1659392.

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