Academic literature on the topic 'Reponse frequence'
Create a spot-on reference in APA, MLA, Chicago, Harvard, and other styles
Consult the lists of relevant articles, books, theses, conference reports, and other scholarly sources on the topic 'Reponse frequence.'
Next to every source in the list of references, there is an 'Add to bibliography' button. Press on it, and we will generate automatically the bibliographic reference to the chosen work in the citation style you need: APA, MLA, Harvard, Chicago, Vancouver, etc.
You can also download the full text of the academic publication as pdf and read online its abstract whenever available in the metadata.
Journal articles on the topic "Reponse frequence"
1
Guignard, B., P. Prayssac, P. Ruel, D. Aigret, P. Coriat, and P. Viars. "Evolution De La Frequence Cardiaque En Reponse A l'Augmentation Peroperatoire De La Fraction Expiree De Desflurane." Annales Françaises d'Anesthésie et de Réanimation 14 (January 1995): R226. http://dx.doi.org/10.1016/s0750-7658(05)81260-2.
Full text
2
Zhou, Jia Mei, Guo Wang Meng, Yao Yao Hu, and Cai Zhang Xu. "Experimental Study on Fiber Concrete Lining in Tunnel with Seismic Dynamic Response." Advanced Materials Research 671-674 (March 2013): 1126–30. http://dx.doi.org/10.4028/www.scientific.net/amr.671-674.1126.
Full textAbstract:
Sesmic dynamic response of Fiber Reinforced Concrete tunnel lining is studied in contrast to the plain concrete. Based on similar theory, model test has been carried out through the 5m×5m triaxial shaking table by inputting sesmic wave, then the damage characteristics of tunnel lining is acquired.The test results show that both the plain concrete and fiber concrete is brocken by sesmic load, but fracture form is not the same,the crack on Fiber concrete is narrow and sawtooth , the crack on plain concrete is wide and straight.Fiber concrete lining strain-time curve is sawtooth partly, it’s vibration reponse is a little lagger than that of plain concrete.It indicats that kinematic velocity of concrete granule is decreased and sesmic energe is absorbed by fiber cohesive force,then frequence amplitude can be reduced.So fiber concrete can be proved as fine anti-seismic material.
3
Dayal, V. S., M. Mai, and R. D. Tomlinson. "Vestibulo-Ocular (VOR) Abnormalities at High Rotational Frequencies in Patients with Meniere' Disease." Otolaryngology–Head and Neck Surgery 98, no. 3 (March 1988): 211–14. http://dx.doi.org/10.1177/019459988809800306.
Full textAbstract:
Although visual feedback is required to maintain gaze stability during low-frequency rotations (below 1 Hz) because of suboptimal VOR gain in this frequency range, such behavior is not as evident at higher frequencies. Benson1 and Hydén et al.2 noted a steady increase in VOR gain in the higher-frequency range (2 to 5 Hz), where visual feedback has little effect. Similar behavior has also been reported in the monkey models. Eleven patients with diagnoses of Meniere's disease had tests of VOR and VOR cancellations performed with the use of pseudorandom oscillations as high as 5 Hz. The reponses at various frequencies were compared with normal data from 17 subjects. The VOR gain in patients exhibited a more rapid rise at high frequencies than that observed in normal subjects. For example, at 3.5 Hz the normal gain was 1.09, whereas patients exhibited a gain of 1.35 (mean of 11 subjects). When the performance during VOR cancellation tasks was compared, Meniere's patients appeared to be less able to perform these tasks; however, when the values were compared by use of a cancellation index that compensates for any difference in VOR gain, this apparent difference disappeared.
4
Di, Zhi Xin. "Analysis and Application on Frequency-Response Charateristic Based on Multi-Elements in Near-Surface." Applied Mechanics and Materials 490-491 (January 2014): 1548–52. http://dx.doi.org/10.4028/www.scientific.net/amm.490-491.1548.
Full textAbstract:
With the continuously process of prospecting program, our land exploration enter into activity lithostratigrapgy stage. For searching medium and small or subtle reservior, higher seismic data discernibility must be needed. In the explosive source area, surface layer velocity, shot lithology and ghost interface are the three key elements influencing the shot frequency. In view of the trait that the quality of single shot has apparently difference causing by near surface layer Yellow River Delta multiple lithology alternating deposits, we study the characteristics of frequency reponse to lithology and ghost by microseismogram log data, to provide reliable basis for scientific select shooting parameter.
5
Wei, Han, Meng Li, Ying Li, Yao Ge, Henrik Saxén, and Yaowei Yu. "Discrete Element Method (DEM) and Experimental Studies of the Angle of Repose and Porosity Distribution of Pellet Pile." Processes 7, no. 9 (August 23, 2019): 561. http://dx.doi.org/10.3390/pr7090561.
Full textAbstract:
The lumpy zone in a blast furnace is composed of piles formed naturally during burden charging. The properties of this zone have significant effects on the blast furnace operation, including heat and mass transfer, chemical reactions and gas flow. The properties of the layers mainly include the angle of repose and porosity distribution. This paper introduces two methods, the Discharging Method and the Lifting Method, to study the influence of the packing method on the angle of repose of the pile. The relationships of the angle of repose and porosity with physical parameters are also investigated. The porosity distribution in the bottom of a pile shows a decreasing trend from the region below the apex to the center. The coordination number of the particles is employed to explain this change. The maximum of the frequency distribution of it was found to show a negative correlation to the static friction coefficient, but becomes insensitive to the parameter as the static friction coefficient increases above 0.6.
6
Wang, Li-Lih. "Stress Wave Propagation for Nonlinear Viscoelastic Polymeric Materials at High Strain Rates." Journal of Mechanics 19, no. 1 (March 2003): 177–83. http://dx.doi.org/10.1017/s1727719100004184.
Full textAbstract:
ABSTRACTWithout knowing the dynamic constitutive relation of materials under high strain rates, no wave propagation can be correctly analyzed. A Series of experimental and theoretical investigation at high strain rates revealed that the nonlinear viscoelastic behavior of polymers and the related composites are well described by the Zhu-Wang-Tang (ZWT) nonlinear viscoelastic constitutive equation. The impulsive reponse of ZWT materials consists of a rate independent nonlinear elastic response and a high frequency linear viscoelastic response. The dispersion and attenuation of nonlinear viscoelastic waves mainly depend on the effective nonlinearity and the high frequency relaxation time θ2. An “effective influence distance” or “effective influence time” is defined to characterize the wave propagation range where θ2 dominates the impact relaxation process.
7
Vieira, Charles de Souza, Jackson Roberto Guedes da Silva Almeida, Alfredo Anderson Teixeira-Araujo, Loumaíra Carvalho da Cruz, Thamires Santos do Vale, and Sérgio Rodrigues Moreira. "Óleo essencial de eucalipto e resposta cardiovascular em idosos após sessão aguda de exercício isométrico." Saúde e Pesquisa 13, no. 3 (September 1, 2020): 561–70. http://dx.doi.org/10.17765/2176-9206.2020v13n3p561-570.
Full textAbstract:
O objetivo do trabalho foi investigar o efeito agudo do óleo essencial de eucalipto (OEE) nas respostas cardiovasculares de repouso e após sessão de exercício resistido isométrico (ERI). Vinte idosos, após serem submetidos a sessões experimentais com inalação de OEE ou condição controle, permaneceram em recuperação durante 60 min (Rec-60’) para depois realizaram três séries de 1 min (1 min de recuperação entre séries) no ERI, para membro superior dominante em aparelho de preensão manual, com intensidade de 30% da contração voluntária máxima (ERI-30%). Intervalos R-R (iRR) e medidas no domínio da frequência (low frequency – LF e high frequency – HF) além da pressão arterial (PA), frequência cardíaca (FC) e duplo produto (DP) foram avaliados. Não ocorreram diferenças (p>0,05) quando comparadas as sessões (OEE vs.controle) na Rec-60’ e ERI-30%. Diferenças foram encontradas no fator tempo do repouso para Rec-60’ nas variáveis FC e iRR e do repouso para ERI-30% na PA sistólica, PA diastólica e DP. A inalação do OEE não proporcionou alterações significativas nas respostas cardiovasculares e autonômicas de idosos no repouso e após sessão de ERI-30%.
8
Richard, Andy, and Nicolas Rambaux. "Complements to the longitudinal librations of an elastic 3-layer Titan on a non-Keplerian orbit." Proceedings of the International Astronomical Union 9, S310 (July 2014): 21–24. http://dx.doi.org/10.1017/s174392131400773x.
Full textAbstract:
AbstractTitan longitudinal librations are dependent on the satellite internal structure and the elastic behavior of the surface. The elastic deformation of the surface is related to the perturbing potential through the Love theory. In a previous paper, we described the deformation as a response to the tidal potential exerted by Saturn at orbital frequency. Here we improve the tidal deformation reponse by including the effect of the libration angle and the orbital perturbations. We then provide the libration amplitudes associated with the rotational model of a tidally deformed three-layer Titan evolving on a non-Keplerian orbit.
9
Mahad, R., H.-C. Ahmanna, B. Boutakioute, M. Ouali Idrissi, and N. Cherif Idrissi Elganouni. "INFARCTUS OSSEUX ASSOCIES A DES OSTEONECROSESEPIPHYSAIRES CHEZ UN SUJET JEUNE DE DECOUVERTE POST TRAUMATIQUE: A PROPOS DUN CAS ET REVUE DE LITTERATURE." International Journal of Advanced Research 9, no. 4 (April 30, 2021): 832–36. http://dx.doi.org/10.21474/ijar01/12771.
Full textAbstract:
La prevalence de linfarctus osseux est mal definie vue le nombre restreint de cas decrits dans la litterature. Son association avec losteonecroseepiphysaireest frequente. Le diagnostic repose exclusivement sur limagerie, essentiellement la radiographie standard et IRM. Notre travail illustre un cas dinfarctus osseux associe a des osteonecroses epiphysaires chez un sujet jeune de decouverte post traumatique.
10
Teixeira, Luis Augusto. "Knowledge of results frequency in the acquisition of motor skills: transitory and learning effects." Revista Paulista de Educação Física 7, no. 2 (December 20, 1993): 8. http://dx.doi.org/10.11606/issn.2594-5904.rpef.1993.138751.
Full textAbstract:
Considerando que as funções motivacionais e de orientação do conhecimento de resultados (CR) produzem efeitos passageiros sobre o desempenho motor, alguns princípios de aprendizagem aparentemente bem estabelecidos precisam ser revistos. Assim, esse estudo tem como propósito investigar o efeito da freqüência de CR sobre a aprendizagem de uma tarefa de posicionamento linear, em um movimento de 50 cm. de extensão. Os sujeitos (n = 24), estudantes universitários de ambos os sexos, foram distribuídos por duas condições de prática: (1) grupo 100% - executou 21 tentativas seguidas de CR e (2) grupo 50% - executou 40 tentativas com CR sendo fornecido a cada duas tentativas. Após 10 min. de repouso ativo, ambos os grupos executaram mais 10 tentativas sem CR. Na fase de aquisição os dois grupos tiveram o mesmo desempenho. Na fase de retenção o grupo 50% apresentou uma tendência de desempenho superior. Esses resultados são coerentes com achados prévios, indicando a importância do desenvolvimento do reforço subjetivo utilizando a análise da retroalimentação intrínseca e que o intervalo de repouso após a fase de aquisição é um elemento metodológico relevante a ser considerado para a separação dos efeitos transitórios sobre o desempenho dos efeitos relativamente permanentes que caracterizam a aprendizagem de habilidades motoras
Dissertations / Theses on the topic "Reponse frequence"
1
Gil, Otávio. "Reponse en frequence de microsondes electrochimiques." Paris 6, 1990. http://www.theses.fr/1990PA066762.
Full textAbstract:
L'utilisation de la methode electrochimique pour l'etude des phenomenes hydrodynamiques repose sur la relation entre le courant qui traverse une microelectrode et le gradient de vitesse au voisinage de sa surface. Dans ce travail on apporte des contributions au developpement de cette methode a differents niveaux: 1) determination theorique et verification experimentale des fonctions de transfert massique pour les sondes rectangulaire, circulaire et bi-circulaire. La connaissance de la valeur de ces fonctions permet de remonter aux fluctuations du gradient de vitesse a partir de la mesure experimentale des fluctuations du courant; 2) etude de l'utilisation de l'oxygene dissous dans l'eau comme traceur electrochimique de facon a eliminer les inconvenients de la methode dus a l'emploi de produits chimiques, pour des applications de type industriel; 3) mise au point d'une electrode circulaire tri-segmentee qui permet d'acceder non seulement a l'amplitude mais aussi a la direction du gradient de vitesse parietal moyen; 4) fabrication par une technique de photolithographie d'une bi-sonde circulaire de faible dimension et de geometrie parfaite, qui a ete utilisee dans l'etude de la turbulence parietale. Cette sonde nous a permis de mesurer simultanement des fluctuations dans la direction de l'ecoulement moyen et dans la direction transverse
2
BOUDET, LOIC. "Etude numerique et experimentale du comportement d'un submersible sous houle irreguliere : analyse de la reponse en pilonnement a basse frequence." Paris 6, 1992. http://www.theses.fr/1992PA066419.
Full textAbstract:
Ce memoire decrit une etude numerique et experimentale du comportement d'un corps immerge evoluant a faible vitesse d'avance en presence d'une houle irreguliere. L'objet principal de cette etude est de choisir un modele numerique capable de predire la reponse en pilonnement a basse frequence d'un submersible dont les periodes propres en pilonnement et tangage sont grandes. Deux approches numeriques differentes sont considerees: une approche au second ordre en domaine frequentiel et une methode temporelle simplifiee. Afin de verifier la validite de ces modeles, des mesures experimentales d'efforts verticaux de derive et basse frequence exerces sur un corps immerge sont presentees. Ces experiences ont ete realisees en houle bichromatique et sans vitesse d'avance. L'analyse de la cinematique de houle a fait l'objet d'une attention particuliere: les composantes de houle de second ordre basse frequence (ondes libres et liees) ont notamment ete mesurees. Pendant ces essais, la croissance de composantes de houle parasites a ete observee. Les mesures d'effort ont montre que ces composantes de houle parasites induisaient des efforts basse frequence additionnels significatifs. Les tests numeriques et experimentaux montrent qu'une approche temporelle simplifiee telle que celle proposee semble bien adaptee lorsque le corps n'est pas trop pres de la surface libre. Le modele fonde sur la theorie du second ordre ne presente pas cette limitation mais certaines ameliorations numeriques sont necessaires pour reproduire correctement la sensibilite des efforts basse frequence aux variations d'immersion du submersible
3
Frénet, Dominique. "Application de la technologie multi-éléments à la caractérisation des matériaux par ondes acoustiques de surface en régime impulsionnel." Valenciennes, 1999. https://ged.uphf.fr/nuxeo/site/esupversions/d47c424f-ed1b-4d29-b812-8e210d593fff.
Full textAbstract:
Dans ce manuscrit, nous présentons l'étude théorique et expérimental qui a été menée pour concevoir un dispositif de contrôle par ondes acoustiques de surface, permettant de caractériser localement (sur une profondeur comparable a la longueur d'onde) des matériaux isotropes ou anisotropes. Le dispositif utilise un capteur multi-éléments de forme conique qui a été spécialement conçu à cet effet. Il fonctionne en régime impulsionnel, dans la gamme de fréquences de 1 à 5 mhz. Il est possible, pour remonter aux propriétés mécaniques des matériaux, de mesurer les caractéristiques (vitesse, atténuation, ) de l'onde de surface. Pour en mesurer la vitesse de propagation, différentes méthodes ont été développées en utilisant les possibilités offertes par la technologie multi-éléments. L'originalité de ces méthodes réside dans le fait que les mesures sont effectuées sans mouvoir le traducteur, ce qui permet de limiter l'encombrement du dispositif, du fait de l'absence de système mécanique. Par ailleurs, cette spécificité permet, par rapport aux méthodes existantes (en particulier, la technique v(z)), d'accélérer la procédure de caractérisations. Dans la partie théorique de cette étude, un modèle versatile permettant de simuler en régime harmonique et en régime impulsionnel, le champ incident, le champ réfléchi sur un matériau isotrope ou anisotrope de surface plane et la tension électrique de sortie pour des traducteurs de forme arbitraire, a été développé. Le modèle a été appliqué au cas du traducteur multi-éléments conique et également au cas des traducteurs monolithiques plans de forme rectangulaire ainsi qu'aux traducteurs focalisants de forme sphérique et cylindrique. Il permet non seulement de prédire les contributions géométriques (spéculaires) du champ acoustique réfléchi et le signal correspondant, mais également les contributions rayonnées (non spéculaires) relatives a l'excitation des ondes de surface.
4
Bitsindou, Pierre. "Contribution a l'etude et l'exploration de capteurs a courants de foucault utilisant des bobines plates pour la realisation d'un dispositif de detection selective et de positionnement en regard d'ecrous." Reims, 1989. http://www.theses.fr/1989REIMS002.
Full textAbstract:
On realise un capteur a courant de foucault permettant la detection selective et le positionnement des ecrous, des rivets et des trous places sur des plaques metalliques. Le capteur est constitue d'une bobine plate, formee de 2 spirales gravees sur les faces opposees d'un circuit imprime et inseree dans un circuit oscillant; on etudie la reponse frequentielle pour divers materiaux cibles
5
PERPOLI, PATRICK. "Reponses aux emotions induites chez le volontaire sain." Aix-Marseille 2, 1994. http://www.theses.fr/1994AIX20062.
Full text
6
Heitz, Jean-François. "Propagation d'ondes en milieu non linéaire : applications à la reconnaissance des sols et au génie parasismique." Grenoble 1, 1992. http://www.theses.fr/1992GRE10120.
Full textAbstract:
La propagation d'ondes en milieu non lineaire est etudiee sur les plans theorique, experimental et numerique. Des applications touchant les domaines du genie parasismique et de la reconnaissance in situ des sols sont proposes. Apres un etat des connaissances acquises a ce jour sur le comportement du sol sous sollicitation dynamique, un modele de comportement viscoelastique non lineaire est introduit dans l'equation fondamentale de la dynamique. L'equation du mouvement du sol obtenue exhibe au second membre un terme de source contenant l'ensemble des termes caracteristiques lies a la non-linearite du sol. Une analyse dans l'espace des frequences montre que le comportement non lineaire deviatoire du sol est a l'origine de modifications du contenu spectral au cours de la propagation par rapport au contenu frequentiel de la sollicitation. Une methode iterative de resolution de l'equation du mouvement est utilisee. A chaque iteration, la solution est obtenue explicitement par l'utilisation de transformations fonctionnelles integrales appropriees. Deux essais dynamiques in situ en surface et en puits avec excitation harmonique sont interpretes sur la base de l'approche theorique precedente. Le premier essai a permis essentiellement de mettre en evidence in situ le comportement non lineaire du sol sous sollicitation sinusoidale. Pour le second essai, des calculs simulent la reponse du sol a distance du puits et une methode d'identification de parametres caracteristiques du comportement non lineaire du sol est proposee. Une autre application de l'approche theorique proposee permet d'etudier les effets de site unidimensionnels caracteristiques du comportement non lineaire d'un horizon de sol reposant sur un demi-espace et subissant une sollicitation transitoire de type sismiques. Une extension du calcul en configuration bidimensionnelle est ensuite proposee
7
MARAIS, GAELLE. "Comparaison des reponses cardio-respiratoires et electromyographiques entre des exercices realises avec les membres superieurs ou inferieurs a frequences spontanees : effets des variations de la frequence spontanee de manivellage (doctorat : sciences et techniques des activites physiques et sportives)." Lille 2, 1999. http://www.theses.fr/1999LIL2T020.
Full text
8
Che, Viet Nhat Anh. "Cyclostationary analysis : cycle frequency estimation and source separation." Thesis, Saint-Etienne, 2011. http://www.theses.fr/2011STET4035.
Full textAbstract:
Le problème de séparation aveugle de sources a but de retrouver un ensemble des sources signaux statistiquement indépendants à partir seulement d’un ensemble des observations du capteur. Ces observations peuvent être modélisées comme un mélanges linéaires instantané ou convolutifs de sources. Dans cette thèse, les sources signaux sont supposées être cyclostationnaire où leurs fréquences cycles peuvent être connues ou inconnu par avance. Premièrement, nous avons établi des relations entre le spectre, spectre de puissance d’un signal source et leurs composants, puis nous avons proposé deux nouveaux algorithmes pour estimer sa fréquences cycliques. Ensuite, pour la séparation aveugle de sources en mélanges instantanés, nous présentons quatre algorithmes basés sur diagonalisation conjoint approchées orthogonale (ou non-orthogonales) d’une famille des matrices cycliques multiples moment temporel, or l’approche matricielle crayon pour extraire les sources signaux. Nous introduisons aussi et prouver une nouvelle condition identifiabilité pour montrer quel type de sources cyclostationnaires d’entrée peuvent être séparées basées sur des statistiques cyclostationnarité à l’ordre deux. Pour la séparation aveugle de sources en mélanges convolutifs, nous présentons un algorithme en deux étapes basées sur une approche dans le domaine temporel pour récupérer les signaux source. Les simulations numériques sont utilisés dans cette thèse pour démontrer l’efficacité de nos approches proposées, et de comparer les performances avec leurs méthodes précédentesBlind source separation problem aims to recover a set of statistically independent source signals from a set of sensor observations. These observations can be modeled as an instantaneous or convolutive mixture of the same sources. In this dissertation, the source signals are assumed to be cyclostationary where their cycle frequencies may be known or unknown a priori. First, we establish relations between the spectrum, power spectrum of a source signal and its component, then we propose two novel algorithms to estimate its cycle frequencies. Next, for blind separation of instantaneous mixtures of sources, we present four algorithms based on orthogonal (or non-orthogonal) approximate diagonalization of the multiple cyclic temporal moment matrices, and the matrix pencil approach to extract the source signal. We also introduce and prove a new identifiability condition to show which kind of input cyclostationary sources can be separated based on second-order cyclostationarity statistics. For blind separation of convolutive mixtures of sources signal or blind deconvolution of FIR MIMO systems, we present a two-steps algorithm based on time domain approach for recovering the source signals. Numerical simulations are used throughout this thesis to demonstrate the effectiveness of our proposed approaches, and compare theirs performances with previous methods
9
Silva, Lilian Pinto da. "Estudo da frequencia cardiaca e pressão arterial de repouso e apos bloqueio farmacologico do sistema nervoso autonomo em ratos jovens e velhos." [s.n.], 1999. http://repositorio.unicamp.br/jspui/handle/REPOSIP/314424.
Full textAbstract:
Orientadores: Lourenço Gallo Jr., Roseli GolfettiDissertação (mestrado) - Universidade Estadual de Campinas, Instituto de Biologia
Made available in DSpace on 2018-07-25T07:58:34Z (GMT). No. of bitstreams: 1 Silva_LilianPintoda_M.pdf: 7749286 bytes, checksum: 2414940542adf4d5730647c67a807a90 (MD5) Previous issue date: 1999
Resumo: Neste trabalho o comportamento das variáveis, freqüência cardíaca e pressão arterial de repouso foram estudadas antes, e após bloqueio farmacológico em ratos Wistar jovens (n = 12) e velhos (n = 6). Os animais foram submetidos a cateterização da artéria carótida e veia jugular, e a implantação de eletrodos em posição subcutânea. A fteqüência cardíaca foi obtida a partir do registro eletrocardiográfico e a pressão arterial medida diretamente por meio de cânula conectada a um transdutor de pressão. As atividades simpática e vagal foram avaliadas por bloqueio farmacológico do SNA, empregando-se doses ftacionadas de atropina e propranolol, por via endovenosa. A fteqüência cardíaca controle foi medida antes dos procedimentos de administração das drogas, e a fteqüência cardíaca intrínseca medida após o duplo bloqueio farmacológico. Os resultados mostraram que: a fteqüência cardíaca controle e a intrínseca dos ratos velhos comparadas às dos jovens apresentaram valores mais baixos; em relação ao efeito simpático, efeito vaga!, tônus simpático e tônus vaga! não foram identificadas diferenças entre os animais jovens e velhos; a pressão arterial sistólica e a média dos ratos velhos apresentaram valores mais baixos do que a dos jovens, entretanto em relação a pressão arterial diastólica não foi identificada diferença. Assim, a diminuição da fteqüência cardíaca controle e da fteqüência cardíaca intrínseca observada nos ratos velhos em relação aos jovens com a abordagem experimental empregada, sugere que essa alteração não é dependente dos mecanismos de controle autonômico
Abstract: In this study the behavior of the variables, heart rate and arterial pressure, at the rest were studied before and afier pharmacological blockade in young (n = 12) and old (n = 6) Wistar rats. The animals were submitted to surgery. Two catheters were implanted into carotida artery and jugular vein and electrodes were implanted subcutaneously. The heart rate was obtained :ITom ECG and direct measure of arterial pressure was obtained :ITom pressure transducer. The vagal and sympathetic activities were assessed :ITom pharmacological blockade of the autonomic nervous system, with :ITactionated doses of atropine and propranolol, endovenously. The control heart rate was measured before procedures of drugs administration and intrinsic heart rate measured afier pharmacological blockade. The results showed that: control and intrinsic heart rate of old rats were lower than that observed in young rats; there were no difIerences between old and young rats as regards vagal and sympathetic effects, vagal and sympathetic tonus; the systolic and mean arterial pressure of old rats were lower than that observed in young rats, however, there were no differences between old and young rats as regards diastolic arterial pressure. Then, the reduction of control and intrinsic heart rate observed in old rats regarding young rats with the experimental approach employed, suggests that this alteration are no dependent on mechanisms of autonomic control
Mestrado
Fisiologia
Mestre em Ciências Biológicas
10
Swanepoel, De Wet. "Estimating pure tone behavioural thresholds with the dichotic multiple frequency auditory steady state response compared to an auditory brainstem reponse protocol in normal hearing adults." Diss., 2002. http://hdl.handle.net/2263/30001.
Full textAbstract:
Audiologists are reliant on objective audiometric procedures to predict auditory sensitivity in difficult-to-test populations. A technique to estimate frequency-specific hearing thresholds in a time-efficient way for difficult-to-test populations, who are unable to provide behavioural responses, has long been the hope of audiologists. The auditory brainstem response (ABR) has dominated the field of objective electrophysiological audiometry for the past three decades. Although it provides a useful method of estimating auditory sensitivity, it presents with its own set of limitations. Recently the auditory steady state response (ASSR) has demonstrated promise of addressing the limitations of the ABR as it is an evoked response uniquely suited to frequency-specific measurement. An optimised version of the ASSR, the dichotic multiple frequency (MF) ASSR, has been proposed as a time-efficient way of evaluating different frequencies simultaneously in both ears. The aim of this study was to evaluate the clinical usefulness of the dichotic MF ASSR technique for estimating pure tone behavioural thresholds at 0.5, 1, 2, and 4 kHz, compared to a 0.5 kHz tone burst and broadband click ABR protocol in a sample of normal hearing adults (56 ears). A comparative experimental research design was selected in order to compare thresholds obtained with the different procedures. The results indicated that both the dichotic MF ASSR and a 0.5 kHz tone burst and broadband click ABR protocol provided a reasonable estimation of PT behavioural thresholds in a time-efficient manner for a group of normal hearing subjects. The click ABR did, however, present with 1, 2, and 4 kHz PT threshold estimations that were almost 50 % closer than that of the dichotic MF ASSR according to the mean and normal deviation. This increased accuracy and reliability of the click ABR is however compromised by its lack of frequency-specificity. In the low frequency region of 0.5 kHz, the tone burst ABR and dichotic MF ASSR evidenced estimations of the pure tone threshold that were, on average, very similar. The tone burst ABR, however, presented with a mean threshold slightly (3 dB) closer to the pure tone threshold than the dichotic MF ASSR. The 0.5 kHz dichotic MF ASSR presented with a smaller range of normal deviation in the estimation of pure tone thresholds which suggested a more reliable measure than the 0.5 kHz tone burst ABR. The dichotic MF ASSR evaluation provided eight thresholds (4/ear) in 23 minutes on average compared to 25 minutes on average required by the ABR protocol to evaluate 4 thresholds (2/ear). This research concluded that the dichotic MF ASSR is useful for estimating frequency-specific pure tone thresholds reasonably well in a time-efficient manner but that this technique should be used in a test-battery alongside the ABR. Both the dichotic MF ASSR and the ABR comprise unique qualities that can be combined in a cross-check principle approach in order to provide complementary information that will verify results obtained with each procedure.Dissertation (MA (Communication Pathology))--University of Pretoria, 2006.
Speech-Language Pathology and Audiology
Unrestricted
Books on the topic "Reponse frequence"
1
Peebles, David John. The effect of stimulus frequency on classification accuracy and reponse time. Birmingham: University of Birmingham, 1997.
Find full textBook chapters on the topic "Reponse frequence"
1
Milic, Ljiljana. "Frequency-Reponse Masking Techniques." In Multirate Filtering for Digital Signal Processing, 295–315. IGI Global, 2009. http://dx.doi.org/10.4018/978-1-60566-178-0.ch010.
Full textAbstract:
The initial concept of the frequency-response masking technique was introduced by Neuvo, Cheng-Yu and Mitra (1984). It was shown that the complexity of a linear phase FIR filter can be considerably reduced by using the cascade connection of an interpolated FIR (IFIR) filter and a properly designed FIR filter. The IFIR filter transfer function is obtained by replacing the unit delay z-1 with the delay block z-M, where M is an integer. In this way, the frequency response of the IFIR filter is made periodic. The FIR filter in the cascade is used to eliminate (mask) the images from the IFIR filter frequency response. Two years later, Lim (1986) proposed a complete approach for the application of frequency-response masking technique in designing narrow-band and arbitrary-band linear phase FIR filters. It was shown that the approach given in (Lim, 1986) results in a linear phase FIR filter with a small fraction of nonzero coefficients, and thus is suitable for implementing sharp filters with arbitrary bandwidths. The arithmetic complexity is considerably smaller in comparison with the arithmetic complexity of an optimal FIR filter having the equivalent frequency response. This approach is applied later to IIR filters by Johansson and Wanhammar (1997, 2000). The overall filter is composed of an IIR periodic model filter and its complementary periodic filter, and FIR linearphase masking filters. In this way, the arbitrary-band filter can be designed. For a narrowband filter, the cascade of a periodic filter and masking filter can be used. The frequency-response masking approach is suitable for digital filters with sharp transition bands. Compared to the classical single-filter design, this technique offers the advantage of lower coefficients’ sensitivity, higher computation speed and lower power consumption. Recently, the application of frequency-response masking approach has been extended to filter banks to achieve a sharp band-separation with reduced computational complexity (Furtado, Diniz, Netto, and Saramäki, T. 2005; Rosenbaum, Lövenborg, and Johansson, 2007). In this chapter, we review the frequency-response masking techniques for narrow-band and arbitrary bandwidth IIR filters. We demonstrate through examples that very selective characteristics can be obtained using relatively low-order sub-filters. In this way, stable, low-sensitive filters are obtained.
2
Chen, C. Julian. "Piezoelectric Scanner." In Introduction to Scanning Tunneling Microscopy, 277–98. Oxford University Press, 2021. http://dx.doi.org/10.1093/oso/9780198856559.003.0010.
Full textAbstract:
This chapter discusses the physical principle, design, and characterization of piezoelectric scanners, which is the heart of STM and AFM. The concept of piezoelectricity is introduced at the elementary level. Two major piezoelectric materials used in STM and AFM, quartz and lead zirconate titanate ceramics (PZT), are described. After a brief discussion of the tripod scanner and the bimorph, much emphasis is on the most important scanner in STM and AFM: the tube scanner. A step-by-step derivation of the deflection formula is presented. The in-situ testing and calibration method based on pure electrical measurements is described. The formulas of the resonance frequencies are also presented. To compensate the non-linear behavior of the tube scanner, an improved design, the S-scanner, is described. Finally, a step-by-step procedure to repole a depoled piezo is presented.
3
Sánchez-Pozos, Katy, María de los Ángeles Granados-Silvestre, and María Guadalupe Ortíz-López. "From Pharmacogenetics to Gene Expression: Implications for Precision Medicine in Diabetes." In Drug Metabolism [Working Title]. IntechOpen, 2021. http://dx.doi.org/10.5772/intechopen.97375.
Full textAbstract:
Approximately 25–60% of patients show specific pharmacological responses to a particular drug. We call this interindividual variability (IV) response to drugs affecting their efficacy and the appearance of side effects in individuals. This IV may be due to multifactorial components such as genetic factors (single nucleotide polymorphisms, SNPs; and copy number variations, CNV), environmental stimuli, epigenetic modulation, disease/health conditions, or drug interactions, among others. Therefore, these factors can influence the response to the drug by modifying absorption, metabolism, pharmacokinetics (PK), and pharmacodynamics (PD), causing the loss of treatment efficacy or leading to adverse drug reactions with negative consequences for patients. The knowledge in pharmacogenetics (study of pharmacological consequences of single gene mutations) and pharmacogenomics (study of the influence of many gene or gene patterns in the reponse to drugs), disciplines that seek to predict how a specific individual responds to the administration of a particular drug, has advanced by leaps and bounds thanks to “omics” technologies. Nonetheless, despite, the development of next-generation sequencing platforms and the mapping of the human genome have transformed the field of pharmacogenetics, the translational into clinical practice has been slow. Therefore, identification of SNPs that could affect the expression of pharmacogenes in order to make associations with PK and PD will improve our understanding of genetic effects on drug efficacy and transfer it to the clinic. Type 2 diabetes (T2D) represents a national public health problem, not only because of the high frequency of the disease reported worldwide, but also because of the poor adherence to therapeutic management, whose causes have not yet been clarified. One of the challenges in the management of diseases to reach optimal treatment is the complex genetic background. Hence, the integration of multiple levels of pharmacological information, including variation in gene sequence, impact in drug response, and function of drug targets, could help us to predict sources of interpatient variability in drug effects, laying the basis for precision therapy. Thus, the present chapter aims to collect all the available data about genetic variations in pharmacogenes affecting drug response in T2D and integrate it with their effect on gene expression to elucidate their impact in pharmacological efficacy.
Conference papers on the topic "Reponse frequence"
1
Nijmeijer, Henk. "Convergency and frequency reponse functions in nonlinear systems." In 2007 4th International Conference on Electrical and Electronics Engineering. IEEE, 2007. http://dx.doi.org/10.1109/iceee.2007.4345067.
Full text
2
Rowe, Wayne S. T., Aupi R. As-Saber, Saidatul N. Azemi, and Kamran Ghorbani. "3D frequency selective surfaces with highly selective reponses." In 2015 Loughborough Antennas & Propagation Conference (LAPC). IEEE, 2015. http://dx.doi.org/10.1109/lapc.2015.7366035.
Full text
3
Maschmann, Matthew R., Gregory J. Ehlert, and Jeffery W. Baur. "Piezoresistive Reponse of Aligned Carbon Nanotube Arrays for Flow Sensing Applications." In ASME 2011 Conference on Smart Materials, Adaptive Structures and Intelligent Systems. ASMEDC, 2011. http://dx.doi.org/10.1115/smasis2011-5096.
Full textAbstract:
We investigate the electromechanical sensing capabilities of aligned carbon nanotube (CNT) arrays as a means for a lightweight and simple electromechanical transduction element. CNT array heights of 25 and 350 μm are examined using a modified dynamic mechanical analyzer (DMA) to impart multiple strain-based test configurations while simultaneously measuring electrical resistance. Observed gauge factors range from 12.5 for the 25μm array to greater than 190 for the 350 μm array, with a peak sensitivity of 13,750 ohms/gram force achieved for the 350 μm array. The electromechanical response observed was independent of the examined frequency range, suggesting high fidelity sensory capabilities. Results of this study serve as a preliminary proof of concept for using CNT arrays as a transduction mechanism for a proposed artificial hair sensor for small air vehicles.
4
El-Saeidy, Fawzi M. A. "Effect of Backlash on Vibration Spectrum in Spur Gearboxes Incorporating Sleeve Bearings." In ASME 1991 Design Technical Conferences. American Society of Mechanical Engineers, 1991. http://dx.doi.org/10.1115/detc1991-0244.
Full textAbstract:
Abstract An Analytical model is presented to simulate effect of tooth backlash on vibration spectrum of spur gearboxes incorporating sleeve bearings. Included in the model are: elasticity of shafts, friction between meshing teeth, interaction between gearbox casing and internals, and time-varying tooth backlash (backlash is a function of operating center distance), mesh stiffness (stiffness is calculated based on the strain energies of the tooth that is treated as a cantilever beam of involute shape) and Hertzian mesh damping. The bearing forces are calculated with consideration of bearing radial clearance and system vibrations. The analysis is applied to a single stage gearbox and equations of motion are numerically integrated to obtain system reponse in time domain. This response is transformed into frequency domain (vibration spectrum) using Fast Fourier Transform (FFT) algorithm and samples of the results are shown for different values of tooth backlash. The results show that backlash has a pronounced effect on gearbox vibration and study provides an analysis procedure for predicting such effects.
5
Juarez, Ezequiel, and Dumitru I. Caruntu. "Reduced Order Model of Coaxial Vibrations of Electrostatically Actuated Double Wall Carbon Nanotubes: Frequency Response of Primary Resonance." In ASME 2018 International Design Engineering Technical Conferences and Computers and Information in Engineering Conference. American Society of Mechanical Engineers, 2018. http://dx.doi.org/10.1115/detc2018-85659.
Full textAbstract:
In this paper, the Reduced Order Method (ROM) and the Method of Multiple Scales (MMS) are used to investigate the influences of dimensionless damping and voltage parameters on the amplitude-frequency response of an electrostatically actuated double-walled carbon nanotube (DWCNT). The forces responsible for the nonlinearities in the vibrational behavior are intertube van der Waals and electrostatic forces. Soft AC excitation and small viscous damping forces are assumed. Herein, the coaxial case is investigated. In this mode of vibration, the outer and inner carbon nanotubes move synchronously (in-phase) with the same maximum tip deflection. The DWCNT structure is modelled as a cantilever beam with Euler-Bernoulli beam assumptions since the DWCNT is characterized with high length-diameter ratio. The results shown assume steady-state solutions in the first-order MMS solution. The analytical approximate solutions provided by MMS are validated numerically by two-term (2T) Time Reponses and AUTO-07P. The two methods in this paper are found to be in excellent agreement at lower amplitudes. Additionally, the two methods are assessed for their advantages and limitations. The importance of the results in this paper are the effect of damping and voltage on the stability of the DWCNT vibration.
6
PIVETTA, RAUL ERD, FELIPE BOVOLINI GRIGOLETTO, LUCAS GIULIANI SCHERER, and ROBINSON FIGUEIREDO DE CAMARGO. "Identificação de Parâmetros Dinâmicos de Máquinas Síncronas de Polos Salientes de Pequena Potência através de Ensaios de Resposta em Frequência." In Seminar on Power Electronics and Control (SEPOC 2021). sepoc, 2021. http://dx.doi.org/10.53316/sepoc2021.011.
Full textAbstract:
O objetivo deste artigo é apresentar a modelagem e a identificação de parâmetros dinâmicos de máquinas síncronas de pequena potência, tal como aquelas empregadas em nano e pico-aproveitamentos hidrelétricos. Inicialmente, no domínio do tempo, o comportamento dinâmico do Gerador Síncrono (GS) é analisado de forma a obter um modelo baseado em coordenadas dq0. Uma vez definido o circuito equivalente da máquina, é realizada uma análise no domínio da frequência para se obter o modelo de pequenos sinais que serve de base para o teste de resposta em frequência com rotor em repouso (SSFR, do inglês Standstill Frequency Response). Assim, é relatada uma aplicação do teste em um GS de 5 kVA, propondo uma abordagem onde são medidas apenas duas funções de transferência do modelo de pequenos sinais e fazendo uso dos testes clássicos de máquinas síncronas para melhorar os resultados. Os parâmetros obtidos são simulados e comparados com a máquina real.