Relevant bibliographies by topics / Vibro fluctuations

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  1. Journal articles
  2. Dissertations / Theses
  3. Book chapters
  4. Conference papers

Academic literature on the topic 'Vibro fluctuations'

Author: Grafiati
Published: 28 May 2022
Last updated: 29 May 2022

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Journal articles on the topic "Vibro fluctuations"

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Dong, Liang, Yuemin Zhao, Liping Peng, et al. "Characteristics of pressure fluctuations and fine coal preparation in gas-vibro fluidized bed." Particuology 21 (August 2015): 146–53. http://dx.doi.org/10.1016/j.partic.2014.08.011.

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Bajic´, Branko, and Andreas Keller. "Spectrum Normalization Method in Vibro-Acoustical Diagnostic Measurements of Hydroturbine Cavitation." Journal of Fluids Engineering 118, no. 4 (1996): 756–61. http://dx.doi.org/10.1115/1.2835506.

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Full-scale vibro-acoustical diagnostic measurements of cavitation in four Francis 6 MW double runner turbines were performed. Two types of sensors were used—a hydrophone sensing waterborne noise at the pressure side of a runner and an accelerometer mounted at various points at the outer turbine casing, facing the runner’s pressure side. The correlation of noise and acceleration intensity with suction-side pressure fluctuations and runner position was checked. A simple but efficient method of spectrum normalization, which rejects the influence of the measurement set characteristics and vibro-acoustical characteristics of a turbine, was developed. The resulting spectra reveal the dependence of cavitation source strength on the turbine power as a function of noise or acceleration frequency.
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Kadmiri, Y., J. Perret-Liaudet, E. Rigaud, A. Le Bot, and L. Vary. "Influence of Multiharmonics Excitation on Rattle Noise in Automotive Gearboxes." Advances in Acoustics and Vibration 2011 (September 5, 2011): 1–6. http://dx.doi.org/10.1155/2011/659797.

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We consider the automotive gearbox rattle noise resulting from vibro-impacts that can occur between the idle gears under excessive velocity fluctuations of the shaft-driving gears imposed by engine torque fluctuation. Even if the rattling phenomenon has no consequence on reliability, it may be particularly annoying for vehicle interior sound quality and acoustic comfort. The main parameters governing such kind of vibrations are the excitation source associated with engine torque fluctuation which can be modeled by an imposed displacement of the driveline, the inertia of the idle gear, the drag torque acting during the free flight motion, and the impact laws. In the case of rattle, it is reasonable to assume that duration of impacts between teeth is very short compared to the excitation period. Then, these impacts are modeled by a coefficient of restitution law. The excitation source is not composed only with fundamental component but also with other harmonic components. This study presents some effects of these additional components on the dynamic response of the idle gear.
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Brancati, Renato, Ernesto Rocca, Daniela Siano, and Massimo Viscardi. "Experimental vibro-acoustic analysis of the gear rattle induced by multi-harmonic excitation." Proceedings of the Institution of Mechanical Engineers, Part D: Journal of Automobile Engineering 232, no. 6 (2017): 785–96. http://dx.doi.org/10.1177/0954407017707670.

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The paper reports a wide vibro-acoustic experimental investigation of the gear rattle phenomenon induced by multi-harmonic excitation. The analysis is performed by using different measurement techniques which allow some of the significant parameters in this type of investigation to be acquired on a specific test rig: the angular rotations of the gears by using encoders; the accelerations obtained from a triaxial accelerometer; the sound pressure level determined by employing both acoustic microphones; the correct evaluation of the acoustic sources by utilizing a p–v sound intensity probe. Performance indices were adopted to compare the dynamic behaviours of the system with respect to some parameters, such as the speed of the pinion, the fluctuations in the speed of the pinion and the lubrication conditions. The results of the comparative analysis show very good agreement between the vibro-acoustic measurements and the results from the encoder-based method; this has helped us to interpret the physical behaviour of the gear pair with respect to the impacts occurring between the teeth during the different phases of the phenomenon. Moreover, the study indicates interesting aspects of the effects of multi-harmonic excitation on the rattle phenomenon, with particular attention to the influence of lubrication on the reduction in the rattle noise.
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Mironova, N. A. "Research of the heat of physical characteristics of fruit ossicles." Power engineering: research, equipment, technology 21, no. 6 (2020): 19–28. http://dx.doi.org/10.30724/1998-9903-2019-21-6-19-28.

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Utilization of fruit seeds plays a special role, since they are a valuable raw material for the oil and fat industry, at the enterprises of which the complex processing of seeds is carried out: oil is obtained from kernels, crumbs and powder are obtained from shells. Before placing the seeds in the oil and fat enterprises, they must be cleaned of impurities and dried, since the seeds extracted from the fruits have an increased humidity of 25-60% and contain a significant amount of impurities in the form of pulp and squeezes. However, due to the lack of specialized equipment for drying fruit seeds in canneries, their supply to the kernel oil plants is declining every year. In this case, tons of seeds are simply destroyed. Attempts to use existing industrial dryers proved to be ineffective, since they do not take into account the structural features of fruit seeds, and are also not very adapted to significant fluctuations in the moisture of raw seeds and the unevenness of their receipt on drying. The most appropriate method of drying fruit seeds is the use of infrared radiation and a vibro-boiling layer.
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Wang, Jing-Shang, Ye Huang, Shuping Zhang та ін. "A Protective Role of Paeoniflorin in Fluctuant Hyperglycemia-Induced Vascular Endothelial Injuries through Antioxidative and Anti-Inflammatory Effects and Reduction of PKCβ1". Oxidative Medicine and Cellular Longevity 2019 (10 квітня 2019): 1–11. http://dx.doi.org/10.1155/2019/5647219.

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Hyperglycemia fluctuation is associated with diabetes mellitus (DM) complications when compared to persistent hyperglycemia. Previous studies have shown that paeoniflorin (PF), through its antiapoptosis, anti-inflammation, and antithrombotic properties, effectively protects against cardiovascular and cerebrovascular disease. However, the mechanism underlying the protection from PF against vascular injuries induced by hyperglycemia fluctuations remains poorly understood. Herein, we investigated the potential protective role of PF on human umbilical vein endothelial cells (HUVECs) subjected to intermittent glucose levels in vitro and in DM rats with fluctuating hyperglycemia in vivo. A remarkable increased apoptosis associated with elevated inflammation, increased oxidative stress, and high protein level of PKCβ1 was induced in HUVECs by intermittently changing glucose for 8 days, and PF recovered those detrimental changes. LY333531, a potent PKCβ1 inhibitor, and metformin manifested similar effects. Additionally, in DM rats with fluctuating hyperglycemia, PF protected against vascular damage as what has been observed in vitro. Taken together, PF attenuates the vascular injury induced by fluctuant hyperglycemia through oxidative stress inhibition, inflammatory reaction reduction, and PKCβ1 protein level repression, suggesting its perspective clinical usage.
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Niccolini Marmont Du Haut Champ, Carlo Alberto, Aristide Fausto Massardo, Mario Luigi Ferrari, and Paolo Silvestri. "Surge prevention in gas turbines: an overview over historical solutions and perspectives about the future." E3S Web of Conferences 113 (2019): 02003. http://dx.doi.org/10.1051/e3sconf/201911302003.

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The aim of the present work is to retrace experimental, analytical and numerical analyses which deal with compressor instability phenomena, such as rotating stall and surge. While the first affects only the machine itself, the second involves the whole energy system. Surge onset is characterized by strong pressure and mass flow rate fluctuations which can even lead to reverse flow through the compressor. Experimental studies on prevention of axial compressor fluid dynamic instabilities, which can be propagated and eventually damage the solid structure, have been carried out by many authors. The first important studies on this topic tried to underline the main aspects of the complex detailed mechanism of surge, by replacing the compression system with an equivalent conceptual lumped parameter model. This is specially meant to capture the unsteady behaviour and the transient response of the compression system itself, particularly its dependence on variations in the volume of discharge downstream and in the settings of the throttle valve at its outlet (which simulates the actual load coupled to the compressor). Greitzer’s model is still regarded as the milestone for new investigations about active control and stabilization of surge and, more generally, about active suppression of aerodynamic instabilities in turbomachinery. During the last years, a lot of simulations and experimental studies about surge have been conducted on multistage centrifugal compressors with different architectures (e.g. equipped with vaneless or vaned diffusers). Moreover, further kinds of analysis try to extend the stable working zone of compressors, identifying stall and surge precursors extractable from information contained in the vibro-acoustical and rotodynamic response of the system.
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Kreeger, Lauren J., Arslaan Arshed, and Katrina M. MacLeod. "Intrinsic firing properties in the avian auditory brain stem allow both integration and encoding of temporally modulated noisy inputs in vitro." Journal of Neurophysiology 108, no. 10 (2012): 2794–809. http://dx.doi.org/10.1152/jn.00092.2012.

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The intrinsic properties of tonically firing neurons in the cochlear nucleus contribute to representing average sound intensity by favoring synaptic integration across auditory nerve inputs, reducing phase locking to fine temporal acoustic structure and enhancing envelope locking. To determine whether tonically firing neurons of the avian cochlear nucleus angularis (NA) resemble ideal integrators, we investigated their firing responses to noisy current injections during whole cell patch-clamp recordings in brain slices. One subclass of neurons (36% of tonically firing neurons, mainly subtype tonic III) showed no significant changes in firing rate with noise fluctuations, acting like pure integrators. In contrast, many tonically firing neurons (>60%, mainly subtype tonic I or II) showed a robust sensitivity to noisy current fluctuations, increasing their firing rates with increased fluctuation amplitudes. For noise-sensitive tonic neurons, the firing rate vs. average current curves with noise had larger maximal firing rates, lower gains, and wider dynamic ranges compared with FI curves for current steps without noise. All NA neurons showed fluctuation-driven patterning of spikes with a high degree of temporal reliability and millisecond spike time precision. Single-spiking neurons in NA also responded to noisy currents with higher firing rates and reliable spike trains, although less precisely than nucleus magnocellularis neurons. Thus some NA neurons function as integrators by encoding average input levels over wide dynamic ranges regardless of current fluctuations, others detect the degree of coherence in the inputs, and most encode the temporal patterns contained in their inputs with a high degree of precision.
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Demb, Jonathan B., Peter Sterling, and Michael A. Freed. "How Retinal Ganglion Cells Prevent Synaptic Noise From Reaching the Spike Output." Journal of Neurophysiology 92, no. 4 (2004): 2510–19. http://dx.doi.org/10.1152/jn.00108.2004.

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Synaptic vesicles are released stochastically, and therefore stimuli that increase a neuron's synaptic input might increase noise at its spike output. Indeed this appears true for neurons in primary visual cortex, where spike output variability increases with stimulus contrast. But in retinal ganglion cells, although intracellular recordings (with spikes blocked) showed that stronger stimuli increase membrane fluctuations, extracellular recordings showed that noise at the spike output is constant. Here we show that these seemingly paradoxical findings occur in the same cell and explain why. We made intracellular recordings from ganglion cells, in vitro, and presented periodic stimuli of various contrasts. For each stimulus cycle, we measured the response at the stimulus frequency (F1) for both membrane potential and spikes as well as the spike rate. The membrane and spike F1 response increased with contrast, but noise (SD) in the F1 responses and the spike rate was constant. We also measured membrane fluctuations (with spikes blocked) during the response depolarization and found that they did increase with contrast. However, increases in fluctuation amplitude were small relative to the depolarization (<10% at high contrast). A model based on estimated synaptic convergence, release rates, and membrane properties accounted for the relative magnitudes of fluctuations and depolarization. Furthermore, a cell's peak spike response preceded the peak depolarization, and therefore fluctuation amplitude peaked as the spike response declined. We conclude that two extremely general properties of a neuron, synaptic convergence and spike generation, combine to minimize the effects of membrane fluctuations on spiking.
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Hayashi, Kumiko, Yuta Tsuchizawa, Mitsuhiro Iwaki, and Yasushi Okada. "Application of the fluctuation theorem for noninvasive force measurement in living neuronal axons." Molecular Biology of the Cell 29, no. 25 (2018): 3017–25. http://dx.doi.org/10.1091/mbc.e18-01-0022.

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Although its importance is recently widely accepted, force measurement has been difficult in living biological systems, mainly due to the lack of the versatile noninvasive force measurement methods. The fluctuation theorem, which represents the thermodynamic properties of small fluctuating nonequilibrium systems, has been applied to the analysis of the thermodynamic properties of motor proteins in vitro. Here we extend it to the axonal transport (displacement) of endosomes. The distribution of the displacement fluctuation had three or four distinct peaks around multiples of a unit value, which the fluctuation theorem can convert into the drag force exerted on the endosomes. The results demonstrated that a single cargo vesicle is conveyed by one to three or four units of force production.
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Dissertations / Theses on the topic "Vibro fluctuations"

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Дробитько, С. А., та В. П. Ларшин. "Исследование вибрационного и звукового датчиков в системе технологической диагностики". Thesis, Сумский государственный университет, 2014. http://essuir.sumdu.edu.ua/handle/123456789/38110.

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Многочисленные исследования отечественных и зарубежных ученых показывают, что при изучении колебаний в упругой системе металлорежущих станков большое значение на качество получаемой информации оказывает способ измерения виброхарактеристик процесса резания и источник информации о виброколебаниях. Модульная технология изготовления пьезоэлектрических вибродатчиков (рис.1, а) и звуковых электретных датчиков (рис.1, б) позволила существенно уменьшить их габаритные размеры с одновременным расширением их динамического диапазона измерений.
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Morilhat, Sylvain. "Modélisation des fluctuations de la pression pariétale d'une couche limite turbulente pour des applications en vibro-acoustique." Thesis, Toulouse, ISAE, 2018. http://www.theses.fr/2018ESAE0041/document.

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Une couche limite turbulente se développant le long d’une paroi présente des fluctuationsde vitesses et de pression importantes. Si la paroi du profil est suffisammentsouple, les fluctuations de pression pariétale peuvent la faire rentrer en vibration cequi induit un rayonnement acoustique de chaque côté de la paroi. Ce scenario estl’un des mécanismes de génération de bruit interne dans les aéronefs. Le but de cettethèse est de proposer un modèle de reconstruction des fluctuations de pression pariétaleafin de prévoir in fine le bruit rayonné. Plutôt que de reposer sur une approchesemi-empirique, les modèles développés dans cette thèse se basent sur la résolutionanalytique de l’équation de Poisson liant les fluctuations de pression aux fluctuationsde vitesses. Ces dernières sont modélisées par exemple à l’aide des profils moyensde la couche limite obtenus grâce à un calcul RANS. La résolution de l’équation dePoisson dans ce contexte a déjà été entreprise en particulier par Lysak et Aupoixet leurs travaux sont le point de départ de cette thèse. Cependant, leur modèle nedonne qu’une description temporelle des fluctuations de pression pariétale alors queles aspects spatiaux sont nécessaires pour une application vibro-acoustique. L’apportde cette thèse consiste donc en une modification de leur modèle afin de palliercette difficulté. En parallèle de ces travaux de modélisation, une expérience de validationen soufflerie a été élaborée et mise en place. Les fluctuations de vitesses ontété mesurées par vélocimétrie laser tandis que les fluctuations de pression pariétaleont été mesurées à l’aide de micro-tiges mobiles. Le modèle initialement développéà été affiné à l’aide de ces mesures. En particulier, une description anisotrope desfluctuations de vitesses a été développée, ce qui est plus cohérent pour un écoulementcisaillé que la description homogène isotrope utilisée jusqu’alors. Les modèlesdéveloppés ont un large recoupement avec le modèle semi-empirique de Corcos quiest la référence utilisée pour les applications en vibro-acoustique. Cependant, desdifférences comportementales importantes aux hautes et basses fréquences ont étémises en évidence. Le modèle de Corcos peut donc être remis en question pour cesplages fréquentielles. Ces résultats théoriques doivent néanmoins être confortés pardes mesures<br>Large pressure and velocity fluctuations are present inside a turbulent boundarylayer developing along a wall. A non-rigid wall can be excited by the wall pressurefluctuations and thus acoustic radiations will be emitted above and bellow the wall.This scenario is one the mechanism of intern noise generation inside aircraft. Theaim of this thesis is to elaborate a turbulent wall pressure fluctuations model inorder to compute the noise radiated by the vibrating wall at the end. Modelsdeveloped during this thesis do not rely on an semi-empirical approach as they arebased on the analytical resolution of Poisson’s equation relating pressure and velocityfluctuations. This kind of approach has already been used by Lysak and Aupoix andtheir work was the starting point of this thesis. However, their model only gives atemporal description of the wall pressure fluctuations while a temporal and spatialdescription is needed for vibro-acoustics application. The major contribution of thisthesis is to modify their model in order to overcome this incapacity. In parallelto this theoretical modelling, a wind-tunnel experimental campaign dedicated tovalidation was designed and implemented. Velocity fluctuations were measured usingLaser Doppler Velocimetry while wall pressure fluctuations were measured usingmobile wall-mounted microphones. The initial model was improved using thesemeasurements. In particular, an anisotropic description of the velocity fluctuationswas developed which is more consistent for a sheared flow than the homogeneous andisotropic description used by Lysak and Aupoix. For a large frequency range, thefinal model behaves similarly to Corcos’ model which is the most used reference forvibro-acoustics applications. However, large differences were highlighted for low andhigh frequencies. Therefore the validity of Corcos’ model is questionable for thesefrequency range. These theoretical results must still be confirmed by experimentaldata
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Morais, Junior Carlos Alberto Vaz de. "Transições de primeira ordem no modelo vidro de spin ising fermiônico em um campo transverso." Universidade Federal de Santa Maria, 2006. http://repositorio.ufsm.br/handle/1/9201.

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Coordenação de Aperfeiçoamento de Pessoal de Nível Superior<br>The present work analyzes the fermionic Ising spin glass model in a transverse magnetic field. The problem is written in the Grand Canonical ensemble with the spin operators represented by bilinear combinations of fermionic fields. The transverse field is a spin "flip" mechanism and inserts quantum fluctuations, which can lead the transition temperature Tj to quantum critical point (QCP). In this case, the phase transition from spin glass to paramagnetic phases occurs in T = o. On the other hand, charge fluctuations controlled by chemical potentiall-L show the existence of a tricritical point. The replica method with replica symmetry and static approximation are used to solve this problem. However, the replica symmetry solution shows some problems, like negative entropy in low temperatures. Thus, the stability conditions are derived to test the generated solution of this IDodel. The main purpose of this work is to study the competition between spin glass and paramagnetic phases with both quantum and charge fluctuations. After the stability conditions are derived, a detailed sight into the generated solution is shown under the form of diagrams phase. The stability conditions, however, show another applications in the present problem, once they can be used, for instance, in the tricritical point derivation.<br>o presente trabalho analisa o modelo vidro de spin Ising com um campo transverso, descrito no ensemble grande canônico, em uma formulação fermiônica, em que os operadores de spin são escritos como uma combinação bilinear de operadores de criação e destruição. Neste modelo, o campo transverso r é um mecanismo de "fiipagem" dos spins, que insere fiutuações de natureza quântica, que podem conduzir a temperatura de transição Tf ao ponto crítico quântico (PCQ). Neste caso, a transição de fase vidro de spin-paramagnética ocorre em T = O. Por outro lado, fiutuações de carga controladas pelo potencial químico mostram a existência de um ponto tricrítico. O método das réplicas com simetria de réplicas e a aproximação estática são usados para resolver este problema. Contudo, a solução com simetria de réplicas apresenta certos problemas na fase vidro de spin como, por exemplo, entropia negativa em baixas temperaturas. Desta forma, as condições de estabilidade são derivadas para testar a solução gerada pelo modelo. O objetivo geral é observar os efeitos combinados das fiutuações quânticas e de carga na competição entre as fase paramagnética e vidro de spin. A partir das condições de estabilidade, as soluções geradas pela simetria de réplicas são vistas detalhadamente na forma de diagramas de fase. As condições de estabilidade, todavia, mostram outras aplicações no presente problema, uma vez que podem, inclusive, ser utilizadas na derivação do ponto tricrítico.
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Allard, Antoine. "Studying in vitro the effect of actin dynamics on membrane tubes Mapping and modeling the nanomechanics of bare protein-coated lipid nanotubes Actin modulates shape and mechanics of tubular membranes Actin dynamics drive cell-like membrane deformation Fluctuations of a membrane nanotube revealed by high-resolution force measurements." Thesis, université Paris-Saclay, 2020. http://www.theses.fr/2020UPASE003.

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Les propriétés mécaniques des nanotubes membranaires (sans la présence du cytosquelette), en particulier la force nécessaire pour les former et les maintenir, sont maintenant bien comprises. Par contre, bien que dans la cellule les nanotubes soient souvent couplés à l’actine, son mécanisme d’action sur de telles structures est inconnu. L’objectif de cette thèse est donc de comprendre comment la dynamique de polymérisation de l’actine affecte la croissance et la stabilité des nanotubes de membrane et contribue à leur scission. Le projet consistera à adresser deux questions principales : - comment la force pour maintenir un nanotube de membrane évolue en présence du cytosquelette d’actine ? - comment la structure du réseau d’actine (taille de la maille, composition, dynamique) détermine les effets mécaniques observés ? La dynamique de l’actine stabilise-t-elle le nanotube ? Les forces générées par la polymérisation peuvent-elles provoquer une scission des nanotubes ? La structure du réseau d’actine permet-elle d’expliquer ces deux effets opposés ? Quel est l’effet de l’ajout de myosines, moteurs moléculaires capables de faire coulisser les filaments d’actine entre eux et de créer une contrainte mécanique supplémentaire dans le réseau ? Ces questions indissociables seront étudiées en collaboration entre les équipes de C. Sykes à l’Institut Curie (Paris), et de C. Campillo et S. Labdi au LAMBE (Evry)<br>The mechanics of membrane nanotubes (without the presence of the cytoskeleton), especially the force needed to form and maintain a nanotube, are now well understood. But, although in the cell the nanotubes are often coupled with actin, its action mechanism on such structures is unknown. The objective of this thesis is to understand how actin polymerization dynamics affect the growth and stability of membrane nanotubes and may contribute to their scission. The project will address two main questions: - How the force to maintain a membrane nanotube evolves in presence of a reconstituted actin cytoskeleton? - How the structure of the actin network (mesh size, composition, dynamic) determines its mechanical effect on the nanotube? Does actin dynamics stabilize the nanotube? Are the forces generated by actin polymerization able to cut nanotubes? Does the structure of the actin network explain these two opposite effects? What is the effect of adding myosins, molecular motors able to create additional mechanical stress in the network? These inseparable issues will be studied in collaboration between the teams of C. Sykes at the Institut Curie (Paris), and C. Campillo and S. Labdi in LAMBE (Evry)
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Book chapters on the topic "Vibro fluctuations"

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Collini, M., L. D’Alfonso, M. Caccia, et al. "In Vitro–In Vivo Fluctuation Spectroscopies." In Optical Fluorescence Microscopy. Springer Berlin Heidelberg, 2010. http://dx.doi.org/10.1007/978-3-662-45849-5_10.

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Voronin, Leon L. "Analysis of Fluctuations of Minimal EPSPs in Vitro: Quantal Model." In Studies of Brain Function. Springer Berlin Heidelberg, 1993. http://dx.doi.org/10.1007/978-3-642-47615-0_16.

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Tawada, K., M. Toyoda, Y. Imafuku, and A. Yamada. "Fluctuation Correlation in the Sliding Movement Generated by Protein Motors In Vitro." In Advances in Experimental Medicine and Biology. Springer US, 1998. http://dx.doi.org/10.1007/978-1-4684-6039-1_6.

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Eltze, Lara, Maren Eltze, and Antonio Garcia. "Variability of Saliva Viscosity - Potential Impact." In In Vitro Diagnostics [Working Title]. IntechOpen, 2020. http://dx.doi.org/10.5772/intechopen.93933.

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As novel COVID-19 testing develops, saliva has become of increasing interest as an alternate biological sample for rapid testing. The appeal in saliva-based testing lies within the ease of which samples are collected, as well as patient comfort throughout the collection process. With this, it has become increasingly important to delineate the characteristics of saliva viscosity due to its effects on the movement and interactions of the substances and molecules found within it. The characteristics that affect saliva viscosity include the presence of aggregates, variations in temperature, and time elapsed between sample collection and testing. Understanding how physicochemical properties and temperature affect saliva’s viscosity are important in generating guidelines for proper sample handling in saliva testing to ensure consistent and reliable results. In this study, passive sampling of saliva was analyzed. This type of collection ensures a more uniform saliva composition, suggesting that variations in viscosity can be attributed solely to modifications in saliva handling post-collection. The data suggested that saliva viscosity is greatest immediately following collection of the saliva sample, increases with higher quantities of aggregates in saliva, and decreases tremendously when the sample has been frozen and thawed to room temperature. These findings suggest that to ensure accuracy and uniformity in quantitative saliva-based test results, protocols should favor the testing of a sample immediately following its collection. The implications of these results in optimizing saliva testing are far reaching. The value of saliva based testing extends far beyond COVID-19 or other disease testing. It is also gaining utility in understanding daily fluctuations in hydration state and in other wellness applications.
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Whitten, Steven T., Bertrand E. García‐Moreno, and Vincent J. Hilser. "Ligand Effects on the Protein Ensemble: Unifying the Descriptions of Ligand Binding, Local Conformational Fluctuations, and Protein Stability." In Biophysical Tools for Biologists, Volume One: In Vitro Techniques. Elsevier, 2008. http://dx.doi.org/10.1016/s0091-679x(07)84027-1.

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Lamrani Alaoui, Hafsa, Khalid Oufdou, and Nour-Eddine Mezrioui. "Prevalence, Antimicrobial Resistance and Pathogenicity of Non-O1 Vibrio cholerae in Suburban and Rural Groundwater Supplies of Marrakesh Area (Morocco)." In Vibrios [Working Title]. IntechOpen, 2021. http://dx.doi.org/10.5772/intechopen.96696.

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This synthesis of research work considers the dynamic, antibiotic resistance, hemolytic, and hemagglutination activities of non-O1 Vibrio cholerae in comparison with those of fecal coliforms, fecal streptococci, and Pseudomonas aeruginosa isolated from suburban and rural groundwater supplies in a Marrakesh area (Morocco). In addition, it assesses the influence of some chemical factors on the distribution of all these bacterial groups. The obtained results showed that the prospected well waters contain them at varying abundance degrees while undergoing generally spatial and temporal fluctuations. The total occurrence of these bacteria during the period of study was 94%. Detectable non-O1 V. cholerae was present in 81% of the samples and the mean abundances ranged from 0 to 11100 MPN/100 ml. According to WHO standards for drinking water, they were heavily contaminated and could have significant health risks for the local population consuming them. Non-O1 V. cholerae and the other studied bacteria are virulent since most of them were found to be adhesive, producers of hemolysins and multi-resistant to antibiotics. Pollution activities around the wells lead to an increase of virulence and antimicrobial resistance in groundwater. This shows the role of these bacteria in several cases of gastro-enteric and systemic pathologies noted in Marrakech local population.
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Conference papers on the topic "Vibro fluctuations"

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Perret-Liaudet, Joe¨l, and Emmanuel Rigaud. "Some Effects of Gear Eccentricities on Automotive Rattle Noise." In ASME 2007 International Design Engineering Technical Conferences and Computers and Information in Engineering Conference. ASMEDC, 2007. http://dx.doi.org/10.1115/detc2007-34794.

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This study deals with the problem of automotive gear rattle noise, primary caused by the engine torque fluctuations. Even if the rattling phenomenon has no consequence on reliability, it may be particularly annoying for vehicle interior sound quality and acoustic comfort. Gear rattle noise results from vibro-impacts that may occur on unloaded gears under excessive fluctuations of the engine torque and driveline dynamic responses. It is reasonable to assume very short time duration for impacts between teeth due to rattle. Then, the main parameters which govern this kind of vibrations are the restitution coefficient introduced for impact modeling, the drag torque acting on the free running wheel during its free flight motion, its inertia and the excitation source which can be modeled by an imposed displacement. This excitation source is often modeled as a harmonic or, sometimes, periodic excitation related to the acyclism behavior of the engine torque fluctuation, at twice the rotation frequency of the primary input shaft. The aim of this study is to deal on several effects of the gear eccentricities considered first as a superimposed periodic excitation source and second as a time varying backlash source. For this end, a simple non-linear oscillator is introduced, based on restitution coefficient for impact modeling. The parameters studied are the operating rotation speed of the input shaft, the inertia of the free running wheel, the drag torque, and the eccentricities compared to the acyclism source. Results are presented through dimensionless parameters.
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Koukounian, Viken N., and Chris K. Mechefske. "FEM-BEM Modeling and Experimental Verification of the Vibro-Acoustic Behaviour of a Section of Aircraft Fuselage." In ASME 2016 International Design Engineering Technical Conferences and Computers and Information in Engineering Conference. American Society of Mechanical Engineers, 2016. http://dx.doi.org/10.1115/detc2016-59163.

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The aerodynamics of an aircraft in flight impose significant stresses upon the structure. Specifically, the mechanics of fluid flow are highly turbulent and, the layer around the aircraft, is referred to the turbulent boundary layer (TBL). The TBL incites a gradient of pressure fluctuations across the fuselage skin resulting in its vibration, and in turn, the generation of noise inside the passenger cabin. The investigation herein proposes a hybrid FEM-BEM modeling technique to predict the aforementioned vibro-acoustic response and an experimental methodology to verify the results (following ASTM and ANSI international testing standards). The described expectations required construction of an acoustic facility consisting of a reverberation chamber and a semi-anechoic room, the development of DAQ software using LabVIEW, an assembly of DAQ hardware using National Instruments products, and the post-processing of test data using Microsoft Excel. The principal quantity of interest is transmission loss (though insertion loss, absorption and other metrics are also calculated). Two panels (0.04in (40thou) and 0.09in (90thou) in thickness) were simulated and tested (0.01in = 1thou). The calculated error of the proposed methodology is within a maximum of 5dB, with an average of 1dB. Ongoing work is investigating complex constructions and the use of damping materials.
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Durant, C., and G. Robert. "Experimental Study of Vibration and Acoustic Radiation of a Pipe Induced by Fully-Developed Turbulent Air Flow." In ASME 1997 International Mechanical Engineering Congress and Exposition. American Society of Mechanical Engineers, 1997. http://dx.doi.org/10.1115/imece1997-0082.

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Abstract Experimental results are presented concerning the vibro-acoustic response of a pipe excited by an internal fully-developed turbulent air flow. The internal wall pressure field generated by the flow, the vibration response and the external acoustic field were measured for Reynolds numbers Re = UoD/v ranging from 5.3 × 105 to 12.5 × 105. The measured statistical properties of the wall pressure field include power spectral densities and cross-spectra. Power spectral density is analyzed after cancellation of a contaminating acoustic component of the wall pressure fluctuations. Convection velocity and correlation lengths are calculated from measured cross-spectra to complete a Corcos model for the cross-spectrum of the turbulent wall pressure fluctuations. The ratio of convection velocity to centerline velocity ranges from 0.7 to 0.8. The coefficient α1 of the standard Corcos model is calculated from the longitudinal correlation length and is found to be around 0.18. To have further information about the convection velocity and correlation lengths in a lower frequency range than presented here, the measured cross-spectral data need to be decontaminated from the acoustic component of the wall pressure. The acceleration response of the pipe wall shows the influence of the structural modes of the test section. Only some of them have a significant influence on the external acoustic field.
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Hambric, Stephen A., David A. Boger, John B. Fahnline, and Robert L. Campbell. "Structure- and Fluid-Borne Acoustic Power Sources in 90 Degree Piping Elbows Excited by Turbulent Flow." In ASME 2006 Pressure Vessels and Piping/ICPVT-11 Conference. ASMEDC, 2006. http://dx.doi.org/10.1115/pvp2006-icpvt-11-93043.

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The structure-borne and fluid-borne vibro-acoustic power spectra induced by turbulent fluid flow over the walls of a continuous 90 degree piping elbow are computed. Although the actual power input by the wall pressure fluctuations to the piping is distributed throughout the elbow, equivalent total powers input to various structural wavetypes (bending, torsion, axial) and fluid (plane waves) at the inlet and discharge of the elbow are computed. The powers at the elbow ‘ports’ are suitable inputs to wave-based and statistically-based models of larger piping systems that include the elbow. Calculations for several flow and structural parameters, including pipe wall thickness, flow speed, and flow Reynolds number are shown. The power spectra are scaled on flow and structural-acoustic parameters so that levels for conditions other than those considered in the paper may be estimated, subject to geometric similarity constraints (elbow radius/pipe diameter). The approach for computing the powers, which links Computational Fluid Dynamics, Finite Element and Boundary Element modeling, and efficient random analysis techniques, is general, and may be applied to other piping system components excited by turbulent fluid flow, such as U-bends and T-sections.
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Goto, Miho, Osamu Inomoto, and Shoichi Kai. "Dynamical Responses of in vitro Neuronal Assemblies to Electrical Stimuli with Chaotic or Stochastic Fluctuations." In NOISE AND FLUCTUATIONS: 19th International Conference on Noise and Fluctuations; ICNF 2007. AIP, 2007. http://dx.doi.org/10.1063/1.2759747.

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Bogdanov, Alexei A., Valeriy Metelev, Toloo Taghian, et al. "Near-infrared oligonucleotide duplex sensors for imaging rapidly activated transcription factors in vitro and in situ." In Dynamics and Fluctuations in Biomedical Photonics XVI, edited by Valery V. Tuchin, Martin J. Leahy, and Ruikang K. Wang. SPIE, 2019. http://dx.doi.org/10.1117/12.2511124.

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Noda, Naoki, Yasuhiro Imafuku, Akira Yamada, and Katsuhisa Tawada. "Fluctuation of actin sliding over myosin thick filaments in vitro." In 2006 IEEE International Symposium on MicroNanoMechanical and Human Science. IEEE, 2006. http://dx.doi.org/10.1109/mhs.2006.320292.

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Mueller, Joachim D., Mohac Tekmen, Lindsey Hillesheim, Weidong Yang, and Yan Chen. "Dual-color fluorescence fluctuation spectroscopy in vitro and in vivo." In Biomedical Optics 2004, edited by Ammasi Periasamy and Peter T. C. So. SPIE, 2004. http://dx.doi.org/10.1117/12.537971.

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Smith, David S., Francis Loth, Hisham S. Bassiouny, Paul Fischer, Jennifer K. Grogan, and Sang-Wook Lee. "Velocity Measurements Inside a Hemodialysis Graft In Vitro Model." In ASME 2004 International Mechanical Engineering Congress and Exposition. ASMEDC, 2004. http://dx.doi.org/10.1115/imece2004-62031.

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Arteriovenous (AV) grafts, which provide an access site for hemodialysis, typically produce a high flow rate environment with pressure and velocity fluctuations; high and low wall shear stress, and vibration. Laser Doppler anemometry (LDA) was performed at Reynolds number (Re) 1200 on an in vitro model, which was constructed from computerized tomography (CT) images of a perfusion fixed plastic cast of a canine venous anastomosis. The results obtained were compared to numerical results and to results previously obtained with idealized in vitro models. This study showed the importance of an accurate geometry in characterizing the flow environment inside an AV graft. Good agreement between the computational fluid dynamics (CFD) and LDA was observed although differences were clearly present.
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Vorp, David A., Donald A. Severyn, and Jon R. Mears. "An Experimental System to Expose Perfused Vascular Segments to Cyclic Bending Ex-Vivo." In ASME 1997 International Mechanical Engineering Congress and Exposition. American Society of Mechanical Engineers, 1997. http://dx.doi.org/10.1115/imece1997-0255.

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Abstract Portions of coronary and other blood vessels undergo cyclic bending due to attachment to the heart or crossing of joints [1,4,9]. Bending of a vascular segment alters the local transmural stresses and strains [5,13] as well as the shear stresses acting on the endothelial surface [8,11]. Fluctuations in both shear stress and in-plane stretch have been shown to influence endothelial cell and smooth muscle cell biology [12]. The purpose of the present work was to create a model to expose perfused, intact vascular segments to cyclic bending in-vitro. Such a system would enable the assessment of the biologic response of vascular tissue to combined alterations in transmural stress and shear stress produced by cyclic bending.
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