Dissertations / Theses on the topic 'Mechanical resonantor'
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Slagmolen, Bram Johannes Jozef, and BRAM SLAGMOLEN@ANU EDU AU. "Direct Measurement of the Spectral Distribution of Thermal Noise." The Australian National University. Faculty of Science, 2005. http://thesis.anu.edu.au./public/adt-ANU20051128.104552.
Full textArab, Hassani Faezeh. "Resonant nano-electro-mechanical sensors for molecular mass-detection." Thesis, University of Southampton, 2012. https://eprints.soton.ac.uk/336335/.
Full textBeeby, Stephen Paul. "Mechanical isolation of miniature resonant sensors and stress relieving packages." Thesis, University of Southampton, 1997. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.242715.
Full textBrewer, John A. (John Adam). "Low resonant frequency beam design for a piezoelectric energy harvesting device." Thesis, Massachusetts Institute of Technology, 2005. http://hdl.handle.net/1721.1/32874.
Full textIncludes bibliographical references (leaf 24).
The TREAD Act of 2000 proposed rules that will soon make tire pressure sensors standard on all automobiles. The trend seems to be for small chips that can be imbedded in tires and perform sensing, signal processing, and RF transmission in one package. But powering these devices will be another challenge that must be addressed. This project deals with powering these sensors by harvesting environmental vibrational energy and eliminating the need for batteries. Using MEMS technology, a thin film Piezoelectric Micropower Generator device could be constructed. The PMPG is simply a cantilever structure tuned to resonate at environmental frequencies. At resonance, sizable strain is induced in a layer of the beam made from the piezoelectric material, PZT, thereby generating electricity. Recent studies have found that the most available environmental frequencies are on the order of 100 Hz. Current PMPG structures were designed to operate at 20 kHz. This project is aimed at understanding how to design low resonance beams while keeping them compact. Large one-dimensional cantilevers of low resonant frequency would pose serious packaging problems for the device. Two--dimensional spiral beams were designed and analyzed using analytical as well as finite element methods.
(cont.) The dependence on length was found to be a function of 1-1.3 rather than 1-2 of conventional one-dimensional beams. A variety of designs were developed using ANSYS which have resonant frequencies in the target range. The mode shapes were also simulated. To compare analysis with experiments, simple mock-up designs are planned to be fabricated from the polymer SU-8.
by John A. Brewer.
S.B.
Eckert, Bernd. "Analytical and a numerical ground resonance analysis of a conventionally articulated main rotor helicopter." Thesis, Link to the online version, 2007. http://hdl.handle.net/10019/385.
Full textAlbert, Kevin B. (Kevin Bjorn). "Efficient control of series elastic actuators through the exploitation of resonant modes." Thesis, Massachusetts Institute of Technology, 2007. http://hdl.handle.net/1721.1/39743.
Full textIncludes bibliographical references (p. 115-117).
This thesis explores the efficiency potential inherent to series elastic actuators during oscillatory tasks. Series elastic actuators have a spring intentionally placed at the actuator output that provides good force resolution and filters out high frequency disturbances from the environment. These properties are essential for robotic applications in which interactions with the environment are unknown, because they allow the actuators to maintain stable force control while protecting the drive train from harmful loadings. The spring can also be used to store energy similar to the way animals use their tendons during locomotory tasks. This thesis shows that by operating the actuators at the appropriate frequency, the storage of energy by the springs can be translated into large efficiency gains for the actuator. To show the efficiency gains of the actuator, a control scheme was developed that is capable of operating the actuators at and above their resonant frequency. The control scheme was based on spring force control allowing it to provide protection to the drive train while being robust to changes in link inertia due to manipulator configuration or environmental interactions.
(cont.) The control scheme was designed to be sufficient for use in real world applications so as to provide experimental results that are representative of operation on a robot vehicle. The control scheme was implemented on a single-link benchtop test stand which was used to demonstrate the performance of the actuators. Experimental results are presented that demonstrate the conditions under which efficient actuation is possible. By comparing the experimental data to models of the hardware, the mechanisms through which power was lost were determined. The results indicate that at resonance there is the potential to achieve up to twice the efficiency obtained by a rigid actuator, however, in order to do so extra attention is needed in both hardware design and control.
by Kevin B. Albert.
S.M.
Fang, Hui. "Evaluation on mechanical properties of micro/nano-meter scale materials by resonant vibration." 京都大学 (Kyoto University), 2016. http://hdl.handle.net/2433/215220.
Full textSamad, Iskandar. "Mechanical characterisation of thin film materials from resonant testing of MEMS micro beams." Thesis, University of Cambridge, 2008. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.612181.
Full textFlynn, Kevin Joseph. "Defect analysis using resonant ultrasound spectroscopy." [College Station, Tex. : Texas A&M University, 2008. http://hdl.handle.net/1969.1/ETD-TAMU-2348.
Full textZhu, Tianyu M. Eng Massachusetts Institute of Technology. "Design and manufacturing analysis of resonantly coupled circuits and other components used for wireless benefit-denial system." Thesis, Massachusetts Institute of Technology, 2013. http://hdl.handle.net/1721.1/85543.
Full textCataloged from PDF version of thesis.
Includes bibliographical references (pages 74-75).
A new benefit-denial system using RFID technology and inductive heating is under development by ProTeqt Technologies. During the deactivation process, an enabler receives electromagnetic waves and turns the energy to heat, causing the polymeric material inside to expand and create force. An LC circuit in the locking mechanism, acting as a weakly coupled electromagnetic resonator, is used to improve energy transfer efficiency. The design of the LC circuit, as well as the measurement of the resulting force is presented. Due to the manufacturing variability of each component, the force generated by the enabler in the lock is uncertain. In the thesis, an analysis of the manufacturing variability and the distribution of the resulting force was conducted. A simulation model was developed to predict the robustness of the lock system. The test results show that the force generated is significantly more than the force needed, proving that the unlocking process is highly reliable. The result generated by the simulation validates the force test results.
by Tianyu Zhu.
M. Eng. in Manufacturing
Hariri, Akbari Sahand. "Long-Time Transport and Mixing in Cellular Flow Due to Resonant Processes and Chaotic Advection." Master's thesis, Temple University Libraries, 2010. http://cdm16002.contentdm.oclc.org/cdm/ref/collection/p245801coll10/id/68744.
Full textM.S.E.
We present a quantitative theory of resonance-induced mixing in near-integrable, volume-preserving, 3-D, non-autonomous flows. As an example of such a flow we use a simplified model proposed by Solomon and Mezic (2003). When the nominal autonomous flow is subject to time-periodic perturbation, mixing occurs due to resonance processes. We discuss two different resonance phenomena. We show that scattering on resonance is the primary reason for long-time mixing. It is the accumulation of “jumps” in the value of adiabatic invariant that occur during the process of crossing resonance that ultimately leads to chaotic advection and mixing. For multiple crossings, the value of these “jumps” can be considered a random variable. We show that the second moment-of-distribution of the adiabatic invariants over a long time, for a large number of tracers starting from similar initial conditions, follows a linear trend; hence the process can be described by a one-dimensional diffusion equation in the space of adiabatic invariants. Volume fraction of the mixing, as well as the rate of mixing are computed as functions of frequency of perturbation. We describe the transport properties using the evolution of the probability distribution function in the space of adiabatic invariants.
Temple University--Theses
Tanimu, Abdullahi. "Resonant state expansion for non-relativistic quantum mechanics in one dimension." Thesis, Cardiff University, 2018. http://orca.cf.ac.uk/114238/.
Full textPetch, Jason Charles. "Resonant four-wave mixing in krypton." Thesis, Imperial College London, 1996. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.243502.
Full textKrogman, Mitchell S. (Mitchell Spencer). "Design and manufacturing analysis of resonantly coupled circuits and other components used for applied wireless power transmission : application analysis." Thesis, Massachusetts Institute of Technology, 2013. http://hdl.handle.net/1721.1/85791.
Full textCataloged from PDF version of thesis.
Includes bibliographical references (pages 86-87).
This thesis describes the analysis of a locking mechanism designed by ProTeqt Technologies. More specifically, the analysis considers the mechanism after the implementation of a resonantly coupled circuit used to receive and transmit wireless energy. Ultimately, the wireless energy is used to generate heat, which in turn causes a polymeric material to expand, thereby creating a mechanical force to disengage the locking mechanism. The analysis considers the force generated through wireless transmission, as well as the forces required to disengage the locking mechanism. The general physics of wireless energy transmission through resonant coupling is presented, as well as design specifications and manufacturing techniques used to produce the secondary circuit. Force requirements and design specifications that drive the success of the locking mechanism are then discussed before the presentation of coinciding results.
by Mitchell S. Krogman.
M. Eng. in Manufacturing
Rony, Amaury. "Analysis and design of resonant inductively coupled circuits : application to benefit denial solutions for the retail industry." Thesis, Massachusetts Institute of Technology, 2013. http://hdl.handle.net/1721.1/85786.
Full textCataloged from PDF version of thesis.
Includes bibliographical references (pages 81-82).
ProTeqt develops benefit denial solutions that are electromagnetically deactivated. A magnetic field from the deactivation tablet inductively heats an enabler that provides the proper force to disengage the locking mechanism. Its latest design was not functional at one inch above the deactivation tablet, because of significant efficiency losses in the electromagnetic energy transfer. This is problematic when the product's package is thick. In order to improve the maximal functional distance, an LC circuit is inserted inside the locking device. This thesis describes the optimization and integration of the circuit, used as a weakly coupled electromagnetic resonator in wireless energy transfer. The most efficient resonator design is proposed, under the inherent constraints of this application. It is then tested in real situation in order to evaluate the failure rate of the complete device. Some modifications of the enabler are proposed and discussed to maximize the reliability. Finally, a simulation is conducted to test the sensitivity of the results to the circuit manufacturing variability. Under several clearly stated assumptions, it appears that the manufacturing variability of the hand-made enabler is the most significant, although it does not threaten the reliability of the current locking mechanism.
by Amaury Rony.
M. Eng. in Manufacturing
Ibrahim, Mahmoud Ibrahim. "An investigation into the effect of electrostatic actuation and mechanical shock on microstructures." Diss., Online access via UMI:, 2009.
Find full textIncludes bibliographical references.
Ljunggren, Fredrik. "Reduction of resonant vibrations in lightweight floors." Licentiate thesis, Luleå tekniska universitet, Drift, underhåll och akustik, 2002. http://urn.kb.se/resolve?urn=urn:nbn:se:ltu:diva-18006.
Full textEiras, Fernández Jesús Nuño. "Studies on nonlinear mechanical wave behavior to characterize cement based materials and its durability." Doctoral thesis, Universitat Politècnica de València, 2016. http://hdl.handle.net/10251/71439.
Full text[ES] El ensayo de determinación de las frecuencias de resonancia ha sido tradicionalmente empleado para determinar la integridad mecánica de testigos de hormigón, en la evaluación de la conformidad de mezclas de hormigón en diversos ensayos de durabilidad, y en la terminación de propiedades constitutivas como son el módulo elástico y el factor de amortiguamiento. Esta técnica no destructiva ha sido ampliamente apelada para la evaluación de las propiedades mecánicas en todo tipo de ensayos de durabilidad. La evolución del daño es comúnmente evaluada a partir de la reducción del módulo dinámico, producido como resultado de cualquier proceso de fisuración. Sin embargo, el comportamiento mecánico del hormigón es intrínsecamente no lineal y presenta histéresis. Como resultado de un comportamiento tensión-deformación con histéresis, el módulo elástico depende de la deformación. En ensayos dinámicos, la no linealidad del material se manifiesta por una disminución de las frecuencias de resonancia, la cual es inversamente proporcional a la amplitud de excitación. Este fenómeno es normalmente denominado como dinámica rápida. Una vez la excitación cesa, el material experimenta un proceso de relajación por el cual, el módulo elástico es restaurado a aquel en situación de reposo. Este fenómeno es denominado como dinámica lenta. Estos fenómenos ¿dinámicas rápida y lenta¿ encuentran su origen en la fricción interna del material. Por tanto, en materiales basados en cemento, la presencia de microfisuras y las interfaces entre sus constituyentes juegan un rol importante en la no linealidad mecánica del material. En el contexto de evaluación de la durabilidad del hormigón, la evolución del daño está basada en el incremento de histéresis, como resultado de cualquier proceso de fisuración. En esta tesis se investigan tres técnicas diferentes las cuales utilizan el impacto como medio de excitación de las frecuencias de resonancia. La primera técnica consiste en determinar las frecuencias de resonancia a diferentes energías de impacto. La técnica es denominada en inglés: Nonlinear Impact Resonant Acoustic Spectroscopy (NIRAS). Ésta consiste en relacionar el detrimento que el material experimenta en sus frecuencias de resonancia, con el aumento de la amplitud de la excitación. La segunda técnica consiste en investigar el comportamiento no lineal mediante el análisis de la señal correspondiente a un solo impacto. Ésta consiste en determinar las propiedades instantáneas de frecuencia, atenuación y amplitud. Esta técnica se denomina, en inglés, Nonlinear Single Impact Resonant Acoustic Spectroscopy (NSIRAS). Se proponen dos técnicas de extracción del comportamiento no lineal mediante el análisis de las variaciones instantáneas de frecuencia y atenuación. La primera técnica consiste en la discretización de la variación de la frecuencia con el tiempo, mediante un análisis basado en Short-Time Fourier Transform (STFT). La segunda técnica consiste en un ajuste por mínimos cuadrados de las señales de vibración a un modelo que considera las variaciones de frecuencia y atenuación con el tiempo. La tercera técnica empleada en esta tesis puede ser empleada para la evaluación de estructuras in situ. La técnica se trata de un ensayo acusto-elástico en régimen dinámico. En inglés Dynamic Acousto-Elastic Test (DAET). Las variaciones del módulo elástico obtenidas mediante los métodos NIRAS y NSIRAS proporcionan un comportamiento promedio y no permiten derivar las variaciones del módulo elástico en un solo ciclo de vibración. Actualmente, la técnica DAET es la única que permite investigar todo el rango de fenómenos no lineales en el material. Por otra parte, a diferencia de otras técnicas DAET, en este estudio se emplea como contraste una onda continua. El uso de una onda continua permite investigar las variaciones relativas del módulo elástico, para una señal transito
[CAT] L'assaig de determinació de les freqüències de ressonància ha sigut tradicionalment empleat per a determinar la integritat mecànica de testimonis de formigó, en l'avaluació de la conformitat de mescles de formigó en diversos assajos de durabilitat, i en la terminació de propietats constitutives com són el mòdul elàstic i el factor d'amortiment. Esta tècnica no destructiva ha sigut àmpliament apel·lada per a l'avaluació de les propietats mecàniques en tot tipus d'assajos de durabilitat. L'evolució del dany és comunament avaluada a partir de la reducció del mòdul dinàmic, produït com resultat de qualsevol procés de fisuración. No obstant això, el comportament mecànic del formigó és intrínsecament no lineal i presenta histèresi. Com resultat d'un comportament tensió-deformació amb histèresi, el mòdul elàstic depén de la deformació. En assajos dinàmics, la no linealitat del material es manifesta per una disminució de les freqüències de ressonància, la qual és inversament proporcional a l'amplitud d'excitació. Este fenomen és normalment denominat com a dinàmica ràpida. Una vegada l'excitació cessa, el material experimenta un procés de relaxació pel qual, el mòdul elàstic és restaurat a aquell en situació de repòs. Este fenomen és denominat com a dinàmica lenta. Estos fenòmens --dinámicas ràpida i lenta troben el seu origen en la fricció interna del material. Per tant, en materials basats en ciment, la presència de microfissures i les interfícies entre els seus constituents juguen un rol important en la no linealitat mecànica del material. En el context d'avaluació de la durabilitat del formigó, l'evolució del dany està basada en l'increment d'histèresi, com resultat de qualsevol procés de fisuración. En esta tesi s'investiguen tres tècniques diferents les quals utilitzen l'impacte com a mitjà d'excitació de les freqüències de ressonància. La primera tècnica consistix a determinar les freqüències de ressonància a diferents energies d'impacte. La tècnica és denominada en anglés: Nonlinear Impact Resonant Acoustic Spectroscopy (NIRAS). Esta consistix a relacionar el detriment que el material experimenta en les seues freqüències de ressonància, amb l'augment de l'amplitud de l'excitació. La segona tècnica consistix a investigar el comportament no lineal per mitjà de l'anàlisi del senyal corresponent a un sol impacte. Esta consistix a determinar les propietats instantànies de freqüència, atenuació i amplitud. Esta tècnica es denomina, en anglés, Nonlinear Single Impact Resonant Acoustic Spectroscopy (NSIRAS). Es proposen dos tècniques d'extracció del comportament no lineal per mitjà de l'anàlisi de les variacions instantànies de freqüència i atenuació. La primera tècnica consistix en la discretización de la variació de la freqüència amb el temps, per mitjà d'una anàlisi basat en Short-Time Fourier Transform (STFT). La segona tècnica consistix en un ajust per mínims quadrats dels senyals de vibració a un model que considera les variacions de freqüència i atenuació amb el temps. La tercera tècnica empleada en esta tesi pot ser empleada per a l'avaluació d'estructures in situ. La tècnica es tracta d'un assaig acusto-elástico en règim dinàmic. En anglés Dynamic Acousto-Elastic Test (DAET). Les variacions del mòdul elàstic obtingudes per mitjà dels mètodes NIRAS i NSIRAS proporcionen un comportament mitjà i no permeten derivar les variacions del mòdul elàstic en un sol cicle de vibració. Actualment, la tècnica DAET és l'única que permet investigar tot el rang de fenòmens no lineals en el material. D'altra banda, a diferència d'altres tècniques DAET, en este estudi s'empra com contrast una ona contínua. L'ús d'una ona contínua permet investigar les variacions relatives del mòdul elàstic, per a un senyal transitori. A més, permet la inspecció d'elements per mitjà de l'accés per una sola cara.
Eiras Fernández, JN. (2016). Studies on nonlinear mechanical wave behavior to characterize cement based materials and its durability [Tesis doctoral no publicada]. Universitat Politècnica de València. https://doi.org/10.4995/Thesis/10251/71439
TESIS
Premiado
Zheng, Xuqian. "Ultra-Wide Bandgap Crystals for Resonant Nanoelectromechanical Systems (NEMS)." Case Western Reserve University School of Graduate Studies / OhioLINK, 2019. http://rave.ohiolink.edu/etdc/view?acc_num=case1554765522327938.
Full textAgnes, Gregory Stephen. "Performance of Nonlinear Mechanical, Resonant-Shunted Piezoelectric, and Electronic Vibration Absorbers for Multi-Degree-of-Freedom Structures." Diss., Virginia Tech, 1997. http://hdl.handle.net/10919/30740.
Full textPh. D.
Desmaële, Denis. "Design of a planar resonant force sensor with an application to cell mechanics." Paris 6, 2011. http://www.theses.fr/2011PA066477.
Full textAnand, Mantrala. "Transition through resonance in linear and nonlinear systems /." Online version of thesis, 1991. http://hdl.handle.net/1850/10995.
Full textThornton, Andrew Simon Graham. "Resonant tunnelling through zero dimensional quantum dots." Thesis, University of Nottingham, 1998. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.298032.
Full textVlcek, Robert John. "The Identification of Resonant Frequencies Emitted by Violins and Flat Top Guitars." Digital Commons @ East Tennessee State University, 2009. https://dc.etsu.edu/etd/1894.
Full textPhelps, Andrew Duncan. "Characterisation of the subharmonic response of a resonant bubble using a two frequency technique." Thesis, University of Southampton, 1995. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.296433.
Full textSemaan, Marie. "Characterization of the mechanical behavior of growing bone based on new imaging methods." Thesis, Aix-Marseille, 2019. http://www.theses.fr/2019AIXM0129/document.
Full textNowadays, the biomechanical study of bone structures is a challenge for different fields: accidentology, management of bone pathologies, comfort for the elderly, design of innovative prostheses, etc. The aim of this thesis is to provide reference values representative of the quality of child bone by characterizing the mechanical and morphometric properties of growing bone tissue at different scales. Mechanical properties were measured at 2 different scales - mesoscopic and microscopic - in 2 experimental modalities – resonant ultrasound spectroscopy and microindentation. Another part of this thesis concerns the development of a morphometric analysis procedure adapted to bone tissue for the treatment of images obtained by micro-tomography (RX). A better knowledge of juvenile bone tissue is essential to develop dedicated models and thus better understand the pathological mechanisms characteristic of growing bone (greenstick fracture) to improve diagnosis and adapt therapeutic choices for young patients
Nielsen, Michele. "Improving Thermoelectric Figure of Merit through Materials Engineering: MinimizingThermal Conductivity via Lone Pairs and Introducing Resonant Levels to Increase PowerFactor." The Ohio State University, 2014. http://rave.ohiolink.edu/etdc/view?acc_num=osu1397143219.
Full textOrovets, Christine M. "Search for Resonant Impurities in Bismuth and Bismuth-Antimony Alloys: Lithium, Magnesium, and Sodium." The Ohio State University, 2012. http://rave.ohiolink.edu/etdc/view?acc_num=osu1337715464.
Full textEngineer, Bhavin Arun. "The mechanical and resonant behaviour of a dry coupled thickness-shear PZT transducer used for guided wave testing in pipe line." Thesis, Brunel University, 2013. http://bura.brunel.ac.uk/handle/2438/13910.
Full textCooley, Dane A. "Effects of Reclaimed Asphalt Pavement on Mechanical Properties of Base Materials." Diss., CLICK HERE for online access, 2005. http://contentdm.lib.byu.edu/ETD/image/etd1094.pdf.
Full textRoe, Austin R. "RESONANT ACOUSTIC WAVE ASSISTED SPIN-TRANSFER-TORQUE SWITCHING OF NANOMAGNETS." VCU Scholars Compass, 2019. https://scholarscompass.vcu.edu/etd/6029.
Full textAkcakoca, Ugur [Verfasser]. "Electromagnetic Modeling of Nanooptical 2-D Photonic Crystal Structures in Resonant Micro-Opto-Electro-Mechanical Systems: Polarization Selectivity and Tunability / Ugur Akcakoca." Kassel : Universitätsbibliothek Kassel, 2018. http://d-nb.info/1167718712/34.
Full textMalone, James Michael. "An Analysis of the Nonlinear Interaction of Peak Frequencies in Resonant Cavity Flows." The Ohio State University, 2008. http://rave.ohiolink.edu/etdc/view?acc_num=osu1204037947.
Full textForke, Roman. "Mikromechanisches kraftgekoppeltes Sensor-Aktuator-System für die resonante Detektion niederfrequenter Schwingungen." Doctoral thesis, Universitätsbibliothek Chemnitz, 2013. http://nbn-resolving.de/urn:nbn:de:bsz:ch1-qucosa-100498.
Full textThis thesis describes the development and characterization of a micromechanical force coupled oscillator system for the resonant detection of low frequency vibrations. It presents a novel working principle that enables spectral measurements of low frequency vibrations. The low frequency spectral content is converted into a higher frequency range by means of amplitude modulation. Due to the mechanical resonance a narrow band is filtered out of the wide band vibration signal. The remaining frequency content is suppressed. Hence, the spectral information is directly obtained with the sensor system without a fast Fourier transform. The tuning is done with an AC voltage resulting in a simple analysis. The main focuses of the work are the theoretical analysis of this novel sensor principle, the development of the micromechanical sensor structure for the use of the novel principle as well as the development and characterization of a measurement system for the spectral detection of low frequency mechanical vibrations with the developed sensor system
Malhotra, Renu, Kathryn Volk, and Xianyu Wang. "CORRALLING A DISTANT PLANET WITH EXTREME RESONANT KUIPER BELT OBJECTS." IOP PUBLISHING LTD, 2016. http://hdl.handle.net/10150/621405.
Full textVolk, Kathryn, Ruth Murray-Clay, Brett Gladman, Samantha Lawler, Michele T. Bannister, J. J. Kavelaars, Jean-Marc Petit, et al. "OSSOS III—RESONANT TRANS-NEPTUNIAN POPULATIONS: CONSTRAINTS FROM THE FIRST QUARTER OF THE OUTER SOLAR SYSTEM ORIGINS SURVEY." IOP PUBLISHING LTD, 2016. http://hdl.handle.net/10150/621231.
Full textForke, Roman. "Mikromechanisches kraftgekoppeltes Sensor-Aktuator-System für die resonante Detektion niederfrequenter Schwingungen." Doctoral thesis, Universitätsverlag der Technischen Universität Chemnitz, 2012. https://monarch.qucosa.de/id/qucosa%3A19809.
Full textThis thesis describes the development and characterization of a micromechanical force coupled oscillator system for the resonant detection of low frequency vibrations. It presents a novel working principle that enables spectral measurements of low frequency vibrations. The low frequency spectral content is converted into a higher frequency range by means of amplitude modulation. Due to the mechanical resonance a narrow band is filtered out of the wide band vibration signal. The remaining frequency content is suppressed. Hence, the spectral information is directly obtained with the sensor system without a fast Fourier transform. The tuning is done with an AC voltage resulting in a simple analysis. The main focuses of the work are the theoretical analysis of this novel sensor principle, the development of the micromechanical sensor structure for the use of the novel principle as well as the development and characterization of a measurement system for the spectral detection of low frequency mechanical vibrations with the developed sensor system.
Vorobyev, Alexey. "Static and time-dependent mechanical behaviour of preserved archaeological wood : Case studies of the seventeenth century warship Vasa." Doctoral thesis, Uppsala universitet, Tillämpad mekanik, 2017. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-314266.
Full textStötta Vasa
Shi, Yinghui. "Acoustical Performance of Lined Induction Furnace in Electric Field Configuration." University of Dayton / OhioLINK, 2021. http://rave.ohiolink.edu/etdc/view?acc_num=dayton1627658524197215.
Full textEvola, Eric G. "High Figure of Merit Lead Selenide Doped with Indium and Aluminum for Use in Thermoelectric Waste Heat Recovery Applications at Intermediate Temperatures." The Ohio State University, 2012. http://rave.ohiolink.edu/etdc/view?acc_num=osu1338307382.
Full textSienkiewicz, Lukasz Krzysztof. "Concept, implementation and analysis of the piezoelectric resonant sensor / Actuator for measuring the aging process of human skin." Thesis, Toulouse, INPT, 2016. http://www.theses.fr/2016INPT0047/document.
Full textThe main goal of the dissertation was following: preparation of a new concept, implementation and analysis of the piezoelectric resonant sensor/actuator for measuring the aging process of human skin. The research work has been carried out in the framework of cooperation between the INP-ENSEEIHT-LAPLACE, Toulouse, France, and at the Gdansk University of Technology, Faculty of Electrical and Control Engineering, Research Group of Power Electronics and Electrical Machines, Gdask, Poland. A concept of transducer for the characterization of mechanical properties of soft tissues was presented. The piezoelectric resonant, bending transducer, referred to as “unimorph transducer” was chosen from different topologies of piezoelectric benders based on the fulfillment of the stated requirements. The innovation of the project lies in the integration of the dynamic indentation method by using a unimorph as an indentation device. This allows the use of a number of attractive electromechanical properties of piezoelectric transducers. The thesis is divided into seven chapters. Chapter 1 states the thesis and goals of the dissertation. Chapter 2 presents piezoelectric phenomenon and piezoelectric applications in the fields of medicine and bioengineering. Chapter 3 describes the requirements for the developed transducer. The choice of unimorph transducer is justified. Chapter 4 presents an analytical description of the unimorph transducer, including the calculations of static deformations, equivalent circuit description, and description of the contact conditions between the transducer and the tested materials. Chapter 5 contains the numerical analysis of the unimorph transducer using FEM virtual model. Results of static and modal simulations are described for two considered geometries of the transducer. Chapter 6 describes the experimental verification process of analytic and numerical models developed for unimorph transducer. The final chapter includes general conclusions concerning obtained research results and achievements, as well as possible future works. In order to verify the proposition of the thesis a full research cycle was carried out, that covered: analytical study, numerical analysis (FEM simulations), prototype realization, and experimental verification of the considered (developed) piezoelectric sensor/actuator structures
Deniz, Saygin. "Determination Of Relations Between Elastic Properties Of Cement Mortars By Using Destructive And Nondestructive Methods." Master's thesis, METU, 2010. http://etd.lib.metu.edu.tr/upload/2/12611544/index.pdf.
Full texts ratio and strength of these mixtures were observed for different ages. The relationships between these elastic properties are determined and the results obtained from two different nondestructive test methods are compared. Although nondestructive tests made it possible to obtain elastic properties of mortar mixtures, the results revealed that it is very difficult to develop a single relationship between different elastic properties of mortars with varying mixture proportions. This situation is mainly due to the anisotropy and nonlinear behavior of the mortar and the difficulty of describing the actual behavior of mortar by formulations defined for perfectly elastic materials.
Liu, Di. "VIBRATION OF STEEL-FRAMED FLOORS SUPPORTING SENSITIVE EQUIPMENT IN HOSPITALS, RESEARCH FACILITIES, AND MANUFACTURING FACILITIES." UKnowledge, 2015. http://uknowledge.uky.edu/ce_etds/34.
Full textYousfi, Ismail. "Caractérisation de l'endommagement thermique et mécanique dans le mortier par les ondes acoustiques non linéaires." Thèse, Université de Sherbrooke, 2015. http://hdl.handle.net/11143/7941.
Full textRésumé : L'objectif de ce travail est la caractérisation de l’endommagement thermique et mécanique dans le mortier par les ondes acoustiques non linéaires. La corrélation entre les paramètres acoustiques linéaires et non linéaires est basée sur les essais expérimentaux et la modélisation. Des mesures expérimentales des paramètres acoustiques non linéaires en fonction de la taille de la fissure et la température ont été effectuées sur mortier. Les vitesses ont montré une diminution et les paramètres non linéaires ont montré une augmentation en augmentant le degré de fissuration. Pour l’endommagement thermique, des éprouvettes cylindriques ont été préparées et ont été caractérisées par l'étude de la porosité et de la saturation. L'acoustique linéaire (UPV) et l’acoustique non linéaire (génération d'harmoniques) ont été appliquées afin de quantifier l’endommagement. Les essais acoustiques linéaires ont montré que les vitesses transversales, longitudinales et le module d'Young du mortier diminuent en fonction de la température. Les essais acoustiques non linéaires ont montré l'augmentation du bêta est fonction de l’endommagement thermique. Pour l’endommagement mécanique et l'autocicatrisation, des anneaux de mortier ont été préparés et fissurés en contrôlant la taille de chaque fissure. Ensuite, le phénomène d'autocicatrisation est suivi par la perméabilité et des essais acoustiques. Les essais de perméabilité ont montré que le débit d'air et la taille de la fissure diminuent rapidement au cours du premier mois, puis lentement durant le reste du processus d'autocicatrisation. D'autre part, les tests acoustiques non linéaires ont montré que « alpha » et « bêta » diminuent durant le processus de l’autocicatrisation, ce qui signifie que les paramètres non linéaires sont des bons indicateurs pour caractériser ce phénomène. En outre, l'analyse des résultats expérimentaux indique que la technique de résonance de fréquence est plus efficace pour caractériser les défauts dans le mortier que la génération d'harmoniques plus élevés. À partir des essais expérimentaux et dans le but d'obtenir un résultat plus général indépendant de notre cas d’étude, les paramètres non linéaires ont été liés à un index d’endommagement. Une corrélation polynomiale de 2e degré a été établie entre les paramètres non linéaires et l’index d’endommagement. Un modèle numérique basé sur la méthode des volumes finis a été proposé afin d'établir une corrélation entre la taille de la fissure et le flux d'air. Les résultats numériques ont été comparés avec les résultats des tests de perméabilité et montré un bon accord. Les résultats de ce travail représentent un bon départ pour étudier le phénomène de l'autocicatrisation par les ondes acoustiques non linéaires.
Godoy, Tatiane Corrêa de. "Projeto, otimização e análise de incertezas de um dispositivo coletor de energia proveniente de vibrações mecânicas utilizando transdutores piezelétricos e circuito ressonante." Universidade de São Paulo, 2012. http://www.teses.usp.br/teses/disponiveis/18/18149/tde-08082016-154446/.
Full textThe use of piezoelectric materials in the development of devices to harvest energy from mechanical vibrations (Energy Harvesting) has been widely studied in the last decade. Piezoelectric materials can be found in the form of thin layers or patches easily integrated into structures without significant mass increase. The conversion of mechanical energy into electric power is provided by the electromechanical coupling of piezoelectric materials. Most publications in the literature explore the use of resonant electromechanical devices, tuned to the operating frequency of the host structure, thus maximizing the power output given a certain operating condition. The performance of these resonant devices to harvest and store energy is highly dependent on the proper tuning of its resonance frequency with the operation frequency of the system/structure. This work presents a design, optimization and uncertainty analysis of energy harvester device consisting of a plate with tip mass and piezoelectric materials connected to shunt circuits. Two boundary conditions are used for the plate, cantilever (EL) and sliding-free (DL). A coupled finite element model with R and RL circuits, combining equivalent single layer and first order shear deformation theories, was used. The distribution and volume of piezoelectric material and the tip mass coupled to the structure were optimized using a Genetic Algorithm, accounting for both mechanical (mechanical model, geometry, weight) and electric (electric model, storer circuit) analyses. Furthermore, the effect of uncertainties of transducer dielectric and piezoelectric constants and electric inductance connected in series with harvesting circuit was studied. The results indicate that the inclusion of a synthetic inductance can improve energy harvesting performance over a frequency range and also that the geometric optimization may reduce the piezoelectric material volume without diminishing significantly the harvested energy.
Yousfi, Ismail. "Caractérisation de l’endommagement thermique et mécanique dans le mortier par les ondes acoustiques non linéaires." Thesis, Ecole centrale de Lille, 2015. http://www.theses.fr/2015ECLI0009/document.
Full textThe objective of this work is the characterization of heat and mechanical damage in the mortar by the nonlinear acoustic waves. The correlation between non-linear/linear acoustic parameters and damage in mortar is studied based on experiments and modelling. For the heat damage, cylindrical specimens were prepared and were characterized by studying the porosity and saturation. Indeed, the linear acoustic (UPV) and non-linear acoustic (Higher harmonic generation) were applied to characterize the damage. The linear acoustic tests have shown that velocities and modulus of Young of the mortar decreases in function of the temperature. The non-linear acoustic tests have shown that beta increases in function of the temperature.For the mechanical damage. The self-healing phenomenon was characterized by the permeability and the acoustic tests. Indeed, the permeability tests have shown that the airflow and the crack size decreases quickly in the first month then slowly for the rest of the self-healing process. On the other hand, the non-linear acoustic tests shown that the alpha and beta decreases according to the self healing process which means that the nonlinear parameters are a good indicators to characterize the self-healing. Moreover, the analysis of the experimental results indicates that the frequency resonant technique is more efficient to characterize the defects in the mortar than the higher harmonic generation. A polynomial correlations of a 2nd degree was established between the nonlinear parameters and the index damage. The findings of this work should be most appropriate as a foundation for the study of the self healing by the nonlinear acoustic waves
De, Marneffe Bruno. "Active and passive vibration isolation and damping via shunted transducers." Doctoral thesis, Universite Libre de Bruxelles, 2007. http://hdl.handle.net/2013/ULB-DIPOT:oai:dipot.ulb.ac.be:2013/210613.
Full textMany different active control techniques can be used to control the vibrations of a mechanical structure: they however require at least a sensitive signal amplifier (for the sensor), a power amplifier (for the actuator) and an analog or digital filter (for the controller). The use of all these electronic devices may be impractical in many applications and has motivated the use of the so-called shunt circuits, in which an electrical circuit is directly connected to a transducer embedded in the structure. The transducer acts as an energy converter: it transforms mechanical (vibrational) energy into electrical energy, which is in turn dissipated in the shunt circuit. No separate sensor is required, and only one, generally simple electronic circuit is used. The stability of the shunted structure is guaranteed if the electric circuit is passive, i.e. if it is made of passive components such as resistors and inductors.
This thesis compares the performances of the electric shunt circuits with those of classical active control systems. It successively considers the use of piezoelectric transducers and that of electromagnetic (moving-coil) transducers.
In a first part, the different damping techniques are applied on a benchmark truss structure equipped with a piezoelectric stack transducer. A unified formulation is found and experimentally verified for an active control law, the Integral Force Feedback (IFF), and for various passive shunt circuits (resistive and resistive-inductive). The use of an active shunt, namely the negative capacitance, is also investigated in detail. Two different implementations are discussed: they are shown to have very different stability limits and performances.
In a second part, vibration isolation with electromagnetic (moving-coil) transducers is introduced. The effects of an inductive-resistive shunt circuit are studied in detail; an equivalent mechanical representation is found. The performances are compared with that of resonant shunts and with that of active isolation with IFF. Next, the construction of a six-axis isolator based on a Stewart Platform is presented: the key parameters and the main limitations of the system are highlighted.
Doctorat en Sciences de l'ingénieur
info:eu-repo/semantics/nonPublished
Slagmolen, Bram Johannes Jozef. "Direct Measurement of the Spectral Distribution of Thermal Noise." Phd thesis, 2004. http://hdl.handle.net/1885/48192.
Full textChang, Jui-Lun, and 張睿倫. "Investigation and Application of locally resonant mechanical metamaterial." Thesis, 2015. http://ndltd.ncl.edu.tw/handle/56619467710141407918.
Full text國立臺灣大學
工程科學及海洋工程學研究所
103
This article presents methods for modeling, analysis, and design of practical metamaterial with simultaneously negative mass density and Young’s modulus. Metamaterials are man-made materials that make objects exhibit behavior defferent from the general laws of physics by changing the geometry and dimensions. Metamaterial research extends from the electromagnetic into acoustic and solid mechanics. By defferent mechanism such as translational or rotational vibration, elastic solid metamaterials would be the equivalent models of media having negative mass density, negative Young’s modulus, or negative bulk modulus in excitation force. The thesis id divided into three parts. First, through theoretical metamaterial model having double negativities, spring-mass system and trusses construct a practical model. We separate the practical model into four different sizes and expect to find the negative slope line in the dispersion curve. The effect of the practical model is explicitly confirmed by analysis of wave propagation using numerical simulation in ABAQUS. By numerical simulation, we find the practical mode having anomalous wave propagation called backward wave. Sencod, we create two-dimensional acoustic metamaterial having simultaneously negative mass density and Young’s modulus. The dipersion curve of two-dimensional model also has the negative slope line which represents special wave propagation phenomenon. Finally, we try to apply the practical model to the present engineering field.
Huang, Ming-An, and 黃銘安. "Applications of Impact Damper to Reduce Resonant Displacement for Mechanical System." Thesis, 2002. http://ndltd.ncl.edu.tw/handle/92244776962054505420.
Full text國立中正大學
機械系
90
The free vibration of a vibratory system equipped with a resilient im-pact damper is studied. A simple model of impact damper is con-structed using spring, mass and viscous damper. The important feature to be carried out in the analysis of this model is that the deformation of an impact damper during the collision with and the main mass can be formulated; therefore the contact time is taken into consideration. This feature is important for a resilient rather than a rigid impact damper when the noise issue is concerned. An optimization technique was employed to determine locations of impact damper and the clear-ance to reduce the vibration amplitude. Results show that the clear-ance of an effective impact damper should be 1-2 times of the initial displacement of the main mass of the vibration system if the system is stimulated by an initial displacement only. An example of application of an impact damper on a cantilever beam is demonstrated and an ex-periment was performed to validate the theoretical result.