Dissertations / Theses: 'Transmissibility'

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Yee, Abigail K. "Using Group Transmissibility Concepts to Compare Dissimilar Vehicle Platforms." University of Cincinnati / OhioLINK, 2009. http://rave.ohiolink.edu/etdc/view?acc_num=ucin1250525222.

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Ma, Jingjiao. "Pathogenicity and transmissibility of novel influenza viruses." Diss., Kansas State University, 2015. http://hdl.handle.net/2097/19773.

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Doctor of Philosophy
Department of Diagnostic Medicine/Pathobiology
Wenjun Ma
Influenza A virus (IAV) is an enveloped, segmented, negative-sense RNA virus that infects avian species and mammals. Its segmented feature enables antigenic shift which can generate novel IAVs that pose a threat to animal and public health due to lack of immunity to these viruses. Pigs have been considered the “mixing vessels” of influenza A viruses to generate novel reassortant viruses that may threaten animal and public health. Therefore, it is necessary to understand the pathogenicity and transmissibility of newly emerged reassortant viruses in swine. Adding to this complexity is the newly identified bat influenza A-like viruses which have roused interest in understanding the evolutionary history and pandemic potential of bat influenza. At least 10 different genotypes of novel reassortant H3N2 IAVs with gene(s) from 2009 pandemic H1N1 [A(H1N1)pdm09] have been identified in pigs in the United States. To date, only three genotypes of these viruses have been evaluated in animal models leaving the pathogenicity and transmissibility of the other seven genotype viruses unknown. We showed that reassortant viruses with genes from A(H1N1)pdm09 are pathogenic and transmissible in pigs. Further studies showed that avian-like glycine at position 228 of the HA receptor binding site is responsible for inefficient transmission of the reassortant H3N2 IAV with five A(H1N1)pdm09 genes. Studying the recently discovered IAV-like sequences from bats has been hindered by the lack of live virus isolation or culturing. Using synthetic genomics, we successfully rescued modified bat influenza viruses that had the HA and NA coding regions replaced with two classical IAVs. Additional studies were performed with truncations on NS1 protein and substitution of a putative virulence mutation in bat influenza PB2. Virus reassortment experiments demonstrated that bat influenza has limited genetic and protein compatibility with other influenza viruses; however, it readily reassorts with another divergent bat influenza virus. Taken together, our results provide insights into the pathogenicity and transmissibility of novel reassortant H3N2 IAVs in pigs. It also indicates that the bat influenza viruses recently identified are viable viruses that pose little pandemic threat to humans. Moreover, they provide new insights into the evolution and basic biology of influenza viruses.

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Lin, Juhn-Shyue. "Experimental analysis of dynamic force transmissibility through bearings." Connect to resource, 1989. http://rave.ohiolink.edu/etdc/view?acc%5Fnum=osu1207597697.

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Chilakapati, Sindhura, and Sri Lakshmi Jyothirmai Mamidala. "Study of Vibration Transmissibility of Operational Industrial Machines." Thesis, Blekinge Tekniska Högskola, Institutionen för tillämpad signalbehandling, 2016. http://urn.kb.se/resolve?urn=urn:nbn:se:bth-13906.

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Industrial machines during their operation generate vibration due to dynamic forces acting on the machines. This vibration may create noise, abrasion in the machine parts, mechanical fatigue, degrade performance, transfer to other machines via floor or walls and may cause complete shutdown of the machine. To limit the vibration pre-installation, vibration isolation measures are usually employed in workshops and industrial units. However, such vibration isolation may not be sufficient due to varying operating and physical conditions, such as machine ageing, structural changes and new installations etc. Therefore, it is important to assess the quantity of vibration generated and transmitted during true operating conditions. The thesis work is aimed at the estimation of vibrational transmissibility or transfer from industrial machines to floor and to other adjacent installed machines. This study of transmissibility is based on the measurement and analysis of various spectral estimation tools such as Power Spectral Density (PSD), Frequency Response Function (FRF) and Coherence Function. The overall study is divided into three major steps. Firstly, the initial measurements are carried in BTH on simple Single Degree of Freedom (SDOF) systems to gain confidence in measurement and analysis. Then the measurements are performed on a Lathe machine “Quick Turn Nexus 300-II” in a laboratory at BTH. Finally, the measurements are taken on the machines of an Industrial workshop (KOSAB). The analysis results revealed that vibration measurements in industry are challenging and not easy as measurement in labs. Measurements are contaminated by noise from other machines, which degrade the coherence function. However, vibration transferred from one machine to the floor or other machines may be studied using FRF and PSD. Appropriate further isolations may be employed based on the spectral analysis.

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Kennedy, I. "Vibration transmissibility characteristics of fibre and steel reinforced flexible pipes." Thesis, University of Manchester, 1987. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.378334.

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Imai, Natsuko. "Refining baseline estimates of dengue transmissibility and implications for control." Thesis, Imperial College London, 2016. http://hdl.handle.net/10044/1/43961.

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Climate change, globalisation and increased travel, increasing urban populations, overcrowding, continued poverty, and the breakdown of public health infrastructure are among the factors contributing to the 30-fold increase in total dengue incidence in the past 50 years. Consequently, with an estimated 40% of the world's population at risk of infection, dengue is now the world's most important mosquito-borne viral infection. However estimates of dengue transmissibility and burden remain ambiguous. Since the majority of infections are asymptomatic, surveillance systems substantially underestimate true rates of infection. With advances in the development of novel control measures and the recent licensing of the Sanofi Dengvaxia® dengue vaccine, obtaining robust estimates of average dengue transmission intensity is key for estimating both the burden of disease from dengue and the likely impact of interventions. Given the highly spatially heterogeneous nature of dengue transmission, future planning, implementation, and evaluation of control programs are likely to require a spatially targeted approach. Here we collate existing age-stratified seroprevalence and incidence data and develop catalytic models to estimate the burden of dengue as quantified by the force of infection and basic reproduction number. We identified a paucity of serotype-specific age stratified seroprevalence surveys in particular but showed that non-serotype specific data could give robust estimates of baseline transmission. Chapters explore whether estimates derived from different data types are comparable. Using these estimates we mapped the estimated number of dengue cases across the globe at a high spatial resolution allowing us to assess the likely impact of targeted control measures.

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Zhang, Xiaolu. "Measurement and modelling of seating dynamics to predict seat transmissibility." Thesis, University of Southampton, 2014. https://eprints.soton.ac.uk/370542/.

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The transmissibility of a seat depends on the dynamics of both the seat and the human body. Previous studies show that the apparent mass of the body, to which much attention has been paid, has a large influence on the vibration transmissibility of a seat. The influence of the seat dynamics on the seat transmissibility has received less systematic attention. The principal objective of this study was to develop a systematic methodology using finite element methods to model the dynamic interaction between a seat and the human body so as to predict the seat transmissibility. The purpose was to understand how the foam material, the seat structure, and the seat occupant influence the vibration transmitted through seats. The effect of the foam thickness at the seat cushion and the backrest on the transmissibility was investigated experimentally in the laboratory with a SAE J826 manikin and with 12 subjects during exposure to 60-s periods of fore-and-aft and vertical vibration, respectively, in the frequency range 0.5 to 20 Hz at 0.8 ms-2 r.m.s. Increasing the thickness of the foam at the seat cushion decreased the resonance frequency of both the vertical vibration transmitted to the seat cushion and the fore-and-aft vibration transmitted to the backrest, while there was little effect of the foam thickness at the backrest. It appears that the foam at the seat cushion had a predominant effect on the transmission of the vibration. Load-deflection curves were measured at various points across the lateral and fore-and-aft centrelines of a car seat with three different loading rates: 0.5, 1.0 and 2.0 mm/s. The dynamic stiffness of the seat cushion and backrest was measured with 120-s broadband random vibration (1.5 to 15 Hz) with three static preloads and with three vibration magnitudes (0.25, 0.5, and 1.0 ms-2 r.m.s.). With the same deformation, the reaction force was greater during loading than during unloading, showing evidence of hysteresis. The stiffness increased with increasing preload force and tended to decrease with increasing magnitude of vibration, indicating the seat components were nonlinear. The dynamic stiffness was also found to be greater when the seat cushion was constrained with a leather cover than without a leather cover. The transmission of vibration from the seat base to six different positions on a car seat was investigated experimentally in the laboratory with a SAE J826 manikin and with 12 subjects exposed to 120-s periods of random vibration (0.5 to 40 Hz) at three magnitudes (0.4, 0.8, and 1.2 ms-2 r.m.s.) in the fore-and-aft and vertical directions, respectively. The transmissibility from the seat base to the seat cushion surface and frame, to the backrest surface and frame, and to the headrest surface and frame exhibited a peak around 4-5 Hz in the fore-and-aft and vertical directions, respectively. The principal resonance frequency in the transmissibilities to all locations decreased with increasing magnitude of vibration, indicating nonlinearity in the seat-occupant system. There was little effect of the seat track position on the measured seat transmissibilities. The transmissibilities with subjects and with the manikin were different. Based on the experimental studies, models of the seat cushion and the backrest assemblies were built up and calibrated separately using the measured load-deflection curves and dynamic stiffnesses. They were joined to form a complete seat model and integrated with the model of a manikin for further calibration with measured seat transmissibility. The calibrated seat model was combined with a re-calibrated existing human body model to predict the transmissibility of the seat. It was found that by combining a calibrated seat model with a calibrated human body model, and defining appropriate contacts between the two models, the vertical vibration transmissibility of a seat with an occupant can be predicted. The developed seat-occupant model could be further improved to predict fore-and-aft seat transmissibility to the backrest and the dynamic pressure distributions at the interfaces between the human body and the seat.

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Schallhorn, Charles Joseph. "Coherence-based transmissibility as a damage indicator for highway bridges." Diss., University of Iowa, 2015. https://ir.uiowa.edu/etd/2007.

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Vibration-based damage detection methods are used in structural applications to identify the global dynamic response of the system. The purpose of the work presented is to exhibit a vibration-based damage detection algorithm that calculates a damage indicator, based on limited frequency bands of the transmissibility function that have high coherence, as a metric for changes in the dynamic integrity of the structure. The methodology was tested using numerical simulation, laboratory experimentation, and field testing with success in detecting, comparatively locating, and relatively quantifying different damages while also parametrically investigating variables which have been identified as issues within similar existing methods. Throughout both the numerical and laboratory analyses, the results were used to successfully detect damage as a result of crack growth or formation of new cracks. Field results using stochastic operational traffic loading have indicated the capability of the proposed methodology in evaluating the changes in the health condition of a section of the bridge and in consistently detecting cracks of various sizes (30 to 60 mm) on a sacrificial specimen integrated with the bridge abutment and a floor beam. Fluctuations in environmental and loading conditions have been known to create some uncertainties in most damage detection processes; however, this work demonstrated that by limiting the features of transmissibility to frequency ranges of high coherence, the effect of these parameters, as compared to the effect of damage, become less significant and can be neglected for some instances. The results of additional field testing using controlled impact forces on the sacrificial specimen have reinforced the findings from the operational loading in detecting damage.

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Allemang, Matthew R. "Comparison of Automotive Structures Using Transmissibility Functions and Principal Component Analysis." University of Cincinnati / OhioLINK, 2013. http://rave.ohiolink.edu/etdc/view?acc_num=ucin1367944783.

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Deshmukh, Shounak. "Synthesizing Uncorrelated Drive Files for MIMO Transmissibility Measurements on Road Simulators." University of Cincinnati / OhioLINK, 2016. http://rave.ohiolink.edu/etdc/view?acc_num=ucin1471254196.

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Gurav, Hardik. "Experimental Validation of the Global Transmissibility (Direct Method) Approach to Transfer Path Analysis." University of Cincinnati / OhioLINK, 2019. http://rave.ohiolink.edu/etdc/view?acc_num=ucin1563273082454307.

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Lewis, Rachel Taylor. "Isolation and transmissibility of shipboard equipment with carbon fiber reinforced polymer mount." Thesis, Massachusetts Institute of Technology, 2012. http://hdl.handle.net/1721.1/74495.

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Thesis (S.B.)--Massachusetts Institute of Technology, Dept. of Mechanical Engineering, 2012.
Cataloged from PDF version of thesis.
Includes bibliographical references (p. 47).
The isolation and transmissibility of shipboard equipment is important to the function of a ship. The transmission of vibration from an engine to its surroundings can be devastating to sensitive equipment and disrupt normal operations. Isolator pads can be used to dampen transmissions from equipment to the ship and vice versa. In this thesis isolator pads of three different materials were considered: carbon fiber reinforced material (CFRP), steel, and rubber. These isolator pads were paired with two pieces of equipment. The first was a marine diesel engine with a relatively large mass and internal rotation. The second piece of equipment was an electronic chart display and information system (ECDIS) with a relatively small mass and no rotating parts. The rubber isolator pad was not a good isolating pad compared to either CFRP or steel, which had comparable responses to impulse and step inputs as well as transmissibility or isolation. For the marine diesel engine the steel isolator pad was marginally better, while the CFRP was best for the ECDIS.
by Rachel Taylor Lewis.
S.B.

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Harp, Lisa. "Contributions of Silicone Hydrogel Transmissibility and Tear Exchange to Corneal Oxygen Supply." The Ohio State University, 2010. http://rave.ohiolink.edu/etdc/view?acc_num=osu1275496222.

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JOSHI, PRASAD RAMAN. "AN ELASTIC CONTACT THEORY FOR MODELING VIBRATION TRANSMISSIBILITY THROUGH ROLLING CONTACT BEARINGS." University of Cincinnati / OhioLINK, 2004. http://rave.ohiolink.edu/etdc/view?acc_num=ucin1092882073.

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Joshi, Prasad R. "An elastic contact theory for modeling vibration transmissibility through rolling element bearings." Cincinnati, Ohio : University of Cincinnati, 2004. http://rave.ohiolink.edu/etdc/view?acc%5Fnum=ucin1092882073.

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Brierley, Liam. "The ecology of emerging diseases : virulence and transmissibility of human RNA viruses." Thesis, University of Edinburgh, 2017. http://hdl.handle.net/1842/22067.

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Emerging infectious diseases continue to represent serious threats to global human health. Novel zoonotic pathogens are continually being recognised, and some ultimately cause significant disease burdens and extensive epidemics. Research and public health initiatives often face emerging pathogens with limited knowledge and resources. Inferences from empirical modelling have begun to uncover the factors determining cross-species transmission and emergence in humans, and subsequently guide risk assessments. However, the dynamics of virulence and transmissibility during the process of emergence are not well understood. Here, I focus on RNA viruses, a priority pathogen type because of their potential for rapid evolution. I use comparative trait-based analyses to investigate how aspects of both host and virus ecology contribute to the risk of virulence and transmissibility within human RNA viruses. To explore these questions, data were collected via systematic literature search protocols. In the first half of this thesis, I focus on viral determinants of virulence and transmissibility. I ask whether virulence can be predicted by viral traits of tissue tropism, transmission route, transmissibility and taxonomic classification. Using a machine learning approach, the most prominent predictors of severe virulence were breadth of tissue tropism, and nonvector-borne transmission routes. When applied to newly reported viruses as test set, the final model predicted disease severity with 87% accuracy. Next, I assess support for hypothesised routes of adaptation during emergence using phylogenetic state-switching models. Propensity for adaptation in small ‘stepwise’ movements versus large ‘off-the-shelf’ jumps differed between virus taxa, though no single route dominated, suggesting multiple independent trajectories of adaptation to human hosts. In addition, phylogenetic regressions showed vector and respiratory-transmitted viruses to be more likely to progress through early stages of emergence. In the second half of this thesis, I focus on how dynamics of virulence and transmissibility differ with respect to nonhuman host diversity, identity, and ecology. Using a regression framework, I observe that viruses with a broader mammalian host range exhibited higher risk of severe virulence, but lower risk of transmissibility, which may reflect potential trade-offs of host specificity. Furthermore, viruses with artiodactyl hosts exhibited lower risk of severe virulence and viruses with bat or nonhuman primate hosts exhibited higher risk of transmissibility. Next, I test hypotheses that mammal species with faster-paced life history may be predisposed to host viruses with greater virulence and transmissibility. Mammal body mass was used as an established proxy for pace of life history. In regression analyses, mammals with faster-paced life history hosted more viruses with severe virulence, though evidence for a relationship with transmissibility was limited. The broad-scale associations presented in this thesis suggest the evolution of virulence and human-to-human transmissibility during zoonotic emergence is a multifactorial, highly dynamic process influenced by both virus and host ecology. Despite this, general characteristics of high-risk emerging viruses are evident. For example, severe virulence was associated with broad niche diversity of both tissue tropisms at the within-host scale, and host species at the macroecological scale. However, risk factors for virulence and human-to-human transmissibility often did not coincide, which may imply an overarching trade-off between these traits. These analyses can contribute to preparedness and direction within public health strategies by identifying likely candidates for high-impact emergence events among previously known and newly discovered human viruses. The inherent connectivity between RNA viruses, their nonhuman hosts and the resulting implications for human health emphasise the holistic nature of emerging diseases and supports the One Health perspective for infectious disease research.

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Darman, Nasir B. Haji. "Upscaling of two-phase flow in oil-gas systems." Thesis, Heriot-Watt University, 2000. http://hdl.handle.net/10399/570.

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STELZER, GREGORY JON. "A MAGNETORHEOLOGIC SEMI-ACTIVE ISOLATOR TO REDUCE NOISE AND VIBRATION TRANSMISSIBILITY IN AUTOMOBILES." University of Cincinnati / OhioLINK, 2002. http://rave.ohiolink.edu/etdc/view?acc_num=ucin1029363540.

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Wei, Lin. "Predicting seat transmissibility from seat impedance and the apparent mass of the human body." Thesis, University of Southampton, 2000. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.312865.

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Tufano, Saverio. "Dynamic response of the coupled human body and seat in vertical and fore-and-aft direction." Thesis, Universita' degli Studi di Catania, 2011. http://hdl.handle.net/10761/373.

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In many environments vibration is transmitted to a person through a seat. Seats can be designed to reduce the discomfort and the injuries caused by vibration. The efficiency of a seat in reducing vibration depends on the characteristics of the vibration, the characteristics of the seat, and the characteristics of the person sitting on the seat (Griffin, 1990). This research was designed to investigate several aspects of the transmission of vertical and fore-and-aft vibration through polyurethane foams used in seat construction. The research programme was focused on two experiments. The first experiment was designed: (i) to investigate non-linearities in the seat and the human body in the vertical direction and their contributions to seat transmissibility; (ii) to compare the vertical apparent mass of the human body on rigid and soft seats; (iii) to measure and model the vertical dynamic stiffness of polyurethane foam seat cushions and investigate how the dynamic stiffness depends on vibration magnitude and subject characteristics (i.e. sitting weight, and hip breadth). The second experiment was designed: (i) to investigate the dependence of fore-and-aft seat cushion transmissibility on vibration magnitude, foam stiffness and contact with a backrest; (ii) to compare the fore-and-aft apparent masses of the human body on rigid and soft seats; (iii) to measure and model the dynamic stiffness of polyurethane foam seat cushions in the fore-and-aft direction, compare the fore-and-aft and vertical dynamic stiffness of foam, and investigate how fore-and-aft dynamic stiffness depends on subject sitting weight and hip breadth; (iv) to study the linear and non-linear effects of simultaneous vertical and fore-and-aft vibration and investigate whether single-axis transmissibility and single-axis models can be used to predict seat cushion transmissibility in multi-axis vibration environments. Fifteen subjects attended the two experiments. In the first experiment, the vertical force and vertical acceleration at the seat base and vertical acceleration at the seat-subject interface were measured during random vertical vibration excitation (0.25 to 25 Hz) at each of five vibration magnitudes (0.25 to 1.6 ms-2 r.m.s.), with four seating conditions (rigid flat seat and three foam cushions). The measurements are reported in terms of the subject apparent mass on the rigid and foam seat surfaces, and the transmissibility and dynamic stiffness of each of the foam cushions. A frequency domain model was used to identify the dynamic parameters of the foams and to investigate their dependence on subject sitting weight and hip breadth. In the second experiment, the vertical and fore-and-aft forces and accelerations at the seat base and the vertical and fore-and-aft accelerations at the seat-subject interface were measured during random vibration excitation (0.25 to 25 Hz) in fore-and-aft and vertical directions. Using three acceleration magnitudes in each direction (0, 0.25 and 1.0 ms-2 r.m.s.) eight different combinations of vertical and fore-and-aft excitation were investigated with three seating conditions (rigid flat seat and two foam cushions), with and without contact with a rigid vertical backrest. Both the human body and the foams showed nonlinear softening behaviour, which resulted in nonlinear cushion transmissibility in both the vertical and the fore-and-aft direction. The nonlinearities in vertical cushion transmissibility, expressed in terms of changes in resonance frequencies and moduli, were more dependent on human body nonlinearity than on cushion nonlinearity. The vertical apparent masses of subjects sitting on the rigid seat and on foam cushions were similar, but with an apparent increase in damping when sitting on the foams. Fore-and-aft apparent mass was strongly dependent on the use of the backrest. Fore-and-aft apparent masses on rigid and soft seats had similar shapes. The vertical and fore-and-aft dynamic stiffness of foam was found to be nonlinear with vibration magnitude and showed complex correlations with the characteristics of the human body. Foams were stiffer in the horizontal direction than in the vertical direction. Linear cross-coupling between vertical and fore-and-aft transmissibility was found: a small part of the vertical (or fore-and-aft) vibration at the seat base contributes to fore-and-aft (or vertical) vibration at the subject-seat interface. Nonlinear cross-coupling was found in seat transmissibility and foam dynamic stiffness: the softening of the seat-subject system in one axis is affected by the vibration in the perpendicular direction. The author believes that this research increased the current state of knowledge of the dynamics of the seated human body and polyurethane foams and so it represents a step forward in the understanding of the mechanisms involved in the vibration isolation provided by seats.

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Smith, Abraham Jeffrey. "Tissue Loss Syndromes in Acropora cervicornis off Broward County, Florida: Transmissibility, Rates of Skeletal Extension and Tissue Loss." NSUWorks, 2013. http://nsuworks.nova.edu/occ_stuetd/154.

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The high latitude thickets of Acropora cervicornis off Broward County flourish despite the presence of natural and anthropogenic impacts. These populations provided a unique study area in contrast to disease-stricken populations of the Florida Keys. This study used time-sequenced photographs to examine how A. cervicornis was affected by tissue loss attributed to white-band disease during 2007–2008. Variables monitored included healthy colony skeletal extension rates, diseased colony skeletal extension rates, and tissue loss. The transmissibility of the three white-band syndromes found in the Scooter and Oakland thickets was examined through tissue grafting experiments. Skeletal extension rates of healthy and diseased colonies were generally not significantly different. Mean skeletal extension for A. cervicornis colonies in Broward County was observed to be 9.6 cm/y (SD=3.95, Range: 1.02–19.9). Mean linear tissue loss from disease signs was 2.6 mm/d (SD=4.3, Range: 0.023–16.8). Although the majority of active disease lesions caused severe tissue loss upon contact with healthy branches, in 25% of the cases there was no tissue loss. Disease signs were also observed in 10% of the control grafting trials. A. cervicornis thickets in Broward County were growing at rates similar to those observed in this species elsewhere in Florida, but faster than other areas of the Western Atlantic. Tissue loss rate from disease lesions was lower than reported elsewhere. White-band disease and/or other tissue loss syndromes are always present in Broward County, but the low prevalence of affected colonies, inconsistent transmission of a presumptive agent that causes the disease signs, and optimum branch skeletal extension seems to limit effects on the thickets. Results of this research are significant as the current protected status of acroporid corals no longer allows manipulative research such as coral grafting for transmissibility of potential disease pathogens.

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Tsiapoki, Stavroula [Verfasser]. "Transmissibility-based monitoring and combination of damage feature decisions within a holistic structural health monitoring framework / Stavroula Tsiapoki." Hannover : Gottfried Wilhelm Leibniz Universität Hannover, 2018. http://d-nb.info/1198398566/34.

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Van, der Westhuizen Anriette. "The verification of seat effective amplitude transmissibility (SEAT) value as a reliable metric to evaluate dynamic seat comfort." Thesis, Stellenbosch : University of Stellenbosch, 2004. http://hdl.handle.net/10019.1/16453.

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Thesis (MScIng)--University of Stellenbosch, 2004.
ENGLISH ABSTRACT: A rough road vibration stimulus was reconstructed on a shaker platform to assess the dynamic comfort of seven seats by six human subjects. The virtual seat method was combined with a paired comparison procedure to assess subjective dynamic seat comfort. The psychometric method of constants, 1-up-1-down Levitt procedure and a 2-up-1-down Levitt procedure were compared experimentally to find the most accurate and efficient paired comparison scheme. A two-track interleaved, 2-up-1-down Levitt procedure was used for the subjective dynamic seat comfort assessment. SEAT value is an objective metric and has been widely used to determine seat vibration isolation efficiency. There was an excellent correlation (R2 = 0.97) between the subjective ratings and estimated SEAT values on the seat top when the values are averaged over the six subjects. This study suggests that the SEAT values, estimated from averaged seat top transmissibility of six carefully selected subjects, could be used to select the best seat for a specific road vibration input.
AFRIKAANSE OPSOMMING: Ses persone het deelgeneem aan ‘n eksperiment, om die dinamiese ritgemak van sewe stoele te karakteriseer. ‘n Rowwe padvibrasie is vir die doel op ‘n skudplatform geherkonstrueer. Subjektiewe ritgemak is bepaal deur die virtuelestoel metode met ‘n gepaarde, vergelykingstoets te kombineer. Die psigometriese metode van konstantes, die 1-op-1-af Levitt procedure en die 2-op- 1-af Levitt procedure is vergelyk om die mees effektiewe en akkurate vergelykingstoets te vind. ‘n Tweebaan, vervlegde , 2-op-1-af Levitt prosedure het die beste resultate gelewer en is gekies vir die subjektiewe evaluasie van dinamiese ritgemak. SEAT-waarde is ‘n objektiewe maatstaf, wat gebruik word om te bepaal hoe effektief ‘n stoel die insittende van voertuigvibrasie isoleer. Daar was ‘n uitstekende korrelasie (R2 = 0.97) tussen subjektiewe dinamiese ritgemakevaluesies en SEAT-waardes in die vertikale rigting op die stoelkussing as die gemiddelde oor die ses persone bereken word. Uit die resultate van hierdie studie blyk dit dat SEAT-waardes, wat bereken is vanaf die gemiddelde sitplektransmissie van die ses persone, wat verteenwoordigend van die teikenbevolking is, gebruik kan word om die beste stoel vir ‘n spesifieke vibrasieinset te kies.

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Hassan, Pour Dargah Mahmoud. "Effects of Shaker Impedance and Transducer Cross-Axis Sensitivity in Frequency Response Function Estimation." University of Cincinnati / OhioLINK, 2012. http://rave.ohiolink.edu/etdc/view?acc_num=ucin1342729500.

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DeShaw, Jonathan. "Effect of head-neck posture on human discomfort during whole-body vibration." Thesis, University of Iowa, 2010. https://ir.uiowa.edu/etd/487.

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It is well known that sitting posture is associated with discomfort and a number of musculoskeletal disorders. Seat manufacturers have made great strides toward developing seats for equipment which helped in alleviating the vibration transferring to the lower area of the spine; however, increased neck and head motion resulting from these seat designs may have been overlooked. Many cervical spine studies have been developed to estimate the response of the head and neck; however, these current studies do not take head and neck posture into account. The objective of this work was to study and demonstrate the difference in human biomechanical response to WBV when they use different neck postures. Four head and neck postures: up, down, to the side, and normal (straight forward) were investigated. Ten male subjects with ages ranging from 19 to 28 years were used to test each of the four postures, using the discrete sinusoidal frequencies of 2, 3, 4, 5, 6, 7, and 8 Hz at constant amplitudes of 0.8 m/s^2 RMS and 1.15 m/s^2 RMS in the x-direction (fore-and-aft). Subjects were seated in a rigid seat rigidly mounted to a vibration platform and vibration was generated using a six-degree-of-freedom man-rated shaker table. Subjects were tightly coupled to the seat back, using a neoprene vest and 5 straps, in an effort to reduce any relative motion between the seat and the subject. Subjects reported their head and neck discomfort using the Borg CR-10 scale with each of the postures, and then gave a second discomfort rating for the normal posture for each combination. Motion capture and accelerometer data were used to acquire the motion of the seat, C7 vertebrae, and center-of-head motion. The 3D motion of selected points on the heads and necks of the subjects were acquired using a twelve-camera Vicon motion capture system. Accelerometer data at the head, C7, and seat was used to verify the motion capture data. For the head-down posture, the magnitude of the discomfort function was higher than the normal posture. The head-to-side and head-up postures have shown less discomfort have shown less discomfort in the critical resonance area; however, these postures show roughly the same discomfort as the normal posture in other frequency ranges. In these postures, the subjects are using major neck-back muscles which create a stiffer system and may explain why there is a shift in the second peak in the head-to-side and head-up postures. Interestingly, the head-to-side and head-up postures show a similar trend as the normal posture, however, the peak transmissibility is attenuated. In addition, the subject's average discomfort was lower in this range compared to the normal posture. The head-down posture had the highest transmissibility and discomfort overall and suggests that workers in vibration environments should reduce any head-down postures to avoid unwanted head accelerations and discomfort. This work has demonstrated the importance of considering the head-neck posture in future seat-design studies.

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Vo, Thi Thu [Verfasser]. "Studies on transmissibility, cytopathology and control of Tomato chlorotic dwarf viroid and Potato spindle tuber viroid / Thi Thu Vo." Bonn : Universitäts- und Landesbibliothek Bonn, 2018. http://d-nb.info/1160673411/34.

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Patterson, Hope Ann. "The effects of rigid contact lens center thickness, material transmissibility, and blinking on oxygen shortfall of the human cornea." Connect to resource, 1999. http://rave.ohiolink.edu/etdc/view?acc%5Fnum=osu1159556692.

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Vexenat, Julio Alejandro. "The epidemiology of visceral leishmaniasis in Teresina, Piaui State, Brazil, with special emphasis on diagnosis and transmissibility of canine infection." Thesis, London School of Hygiene and Tropical Medicine (University of London), 1998. http://researchonline.lshtm.ac.uk/768480/.

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Visceral leishmaniasis (VL) is endemic in the semi-arid region of north-eastern Brazil. The causative agent is Leishmania chagasi (infantum). The domestic, peri-domestic and anthropophilic sandfly vector is Lutzomyia longipalpis. The domestic dog may be the principal reservoir of infection in endemic urban regions. The primary aim of this project was to study comparative diagnosis and transmissibility of natural and experimental canine VL in the city of T eresina, Piaui state, Brazil. Most (67 %) of human cases of VL in Teresina occurred in children under 5 years of age, adult VL predominated in males, and there was a seasonal increase in incidence of cases. No phenotypic diversity was found between L. chagasi isolates from dogs and humans, although limited comparisons were performed. Clinical diagnosis, parasitological diagnosis and serology were compared in a cohort of 209 dogs, comprised of both symptomatic and asymptomatic animals. Presence of clinical symptoms was not sufficiently sensitive to diagnose canine VL: only 42 % of dogs positive by reference standard criteria (RS positive) were symptomatic. Parasitology was less sensitive than serology for the diagnosis of canine VL and no parasitological test sho~ed more than 60 % sensitivity in comparison with RS criteria. The indirect fluorescent antibody test (IF A T) and DOT -enzyme linked imrnunosorbent assay (DOT -ELISA) were the most sensitive of the serological assays tested. The direct agglutination test (OAT) was highly specific but lacked sensitivity. Serum samples were more sensitive than filter paper blood spot samples. The Lmet2 DNA probe was generally less sensitive than traditional parasitological and serological methods for diagnosis of canine VL, although the probe was useful for screening sandflies for L. chagasi infections (below). The chance of demonstrating parasites in canine VL increased with the serological titre. Nevertheless, parasitoIogicalIy positive dogs could be found among those that were serologically negative. Large numbers of Lu. longipalpis were found in pigsties and chicken houses in the city of Teresina. The Lmet2 probe was shown to be effective for determining prevalence rates of L. chagasi infection in wild caught sandflies. Prevalence of natural infection in sandflies was particularly high when flies were caught in kennels where there were dogs with disseminated cutaneous infections. Experimental studies demonstrated that Lu. longipaJpis could be very readily infected with L. chagasi by feeding on dogs with canine VL and that transmissibility was associated with amastigote infection of the skin. Altered skin of symptomatic dogs was more infective than normal skin of symptomatic animals. Although symptomatic animals were more infective than asymptomatic animals, asymptomatic dogs with normal skin were still infective to large numbers of sandflies and asymptomatic dogs cannot, therefore, be excluded as a significant reservoir of infection. Transmission of experimental canine VL was demonstrated by a single infective sandfly bite. In a cohort of 25 experimental animals many dogs developed discrete, self-curing, cutaneous lesions, typical of cutaneous leishmaniasis. Seroconversion was the most sensitive test for canine VL, but seronegativity was not a reliable indicator of the absence of infection. Bone marrow positivity was only seen in dogs that were serologically positive. Apparent recovery from L. chagasi infection was seen, with serological reversIOn. Aminosidine, dependent on dose, duration of treatment and clinical status of the infected animal, was shown to be capable of producing clinical recovery and clinical cure in a small proportion of infected dogs, but could not be recommended as a systematic method of control. Single applications of ultra-low volume pyrethroid insecticide to individual animal pens was not effective for controlling Lu. iongipaipis. Nevertheless, pyrethroid insecticides had a high residual activity against Lu. iongipalpis when sprayed on to the walls of animal enclosures. Lambda cyhalothrine (ICON) was the most effective of three pyrethroid insecticides tested in the laboratory against Lu. iongipalpis. Overall, this project has produced unique observations on canine VL, supports the fundamental role of the dog as a reservoir host, and explains why culling of seropositive dogs is likely to have limited impact as a disease control strategy.

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Marafiotti, Graziela de Almeida Prado e. Piccino [UNESP]. "Detecção da transmissão vertical do S. mutans e S. sobrinus e relação com o micro-ambiente bacteriano, índice de cárie e cuidados maternos." Universidade Estadual Paulista (UNESP), 2009. http://hdl.handle.net/11449/102649.

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Made available in DSpace on 2014-06-11T19:32:13Z (GMT). No. of bitstreams: 0 Previous issue date: 2009-08-26Bitstream added on 2014-06-13T20:42:58Z : No. of bitstreams: 1 marafiotti_gapp_dr_botfm.pdf: 232028 bytes, checksum: 9028f7cfb913afa87c099ddf2e6179bd (MD5)
Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)
A cárie dentária pediátrica continua sendo uma doença significativa em países em desenvolvimento. A presença de microrganismos cariogênicos na saliva materna pode favorecer a contaminação de seu filho. O desenvolvimento das lesões é fortemente dependente do momento em que ocorreu a infecção; quando precoce, a prevalência de cárie é maior. Detectar a transmissão vertical do S. mutans e S. sobrinus e relação com o micro ambiente bacteriano, índice de cárie e cuidados maternos. Amostra: 60 crianças, ambos os gêneros, de um a três anos de idade e suas respectivas mães. Técnicas utilizadas: PCR e Nested- PCR. Indices de cárie: CPO-D e ceo. Instrumentos: exame clínico e questionário aplicado às mães. Registrou-se: ceo, CPO-D, higiene bucal, cuidados e hábitos de carinho. Resultados. Houve concordância de ausência e de presença de Streptococcus mutans e sobrinus entre mães e filhos, com diferença estatísticamente significante (p<0,05), tanto na placa como na saliva; índices de cárie igual a zero somente em 38,33% das crianças e 10% das mães; maior freqüência de respostas das mães para a questão sobre o não uso de fio dental, duas escovações diárias, visita ao dentista com intervalo de seis meses e prova do alimento do filho com a própria colher. As técnicas PCR e Nested PCR se mostraram adequadas para a detecção de Streptococcus. Houve concordância dos resultados dos filhos e suas respectivas mães quanto à presença/ausência de microrganismos S. sobrinus e S. mutans na placa e saliva, sugerindo a transmissibilidade vertical. Detectou-se um menor índice de cárie dos filhos em relação às suas mães. O Índice de cárie das crianças foi superior ao esperado pela OMS para 2010 e os hábitos de higiene/carinhos relatados pelas mães eram inadequados para com seus filhos...
Dental caries in children is still an expressive disease .The presence of cariogenic microorganisms on maternal saliva might favor contamination of their children. The development of caries lesions is strongly related to the time when infection takes place; the sooner, the higher the caries prevalence. To detect S.mutans and S.sobrinus vertical transmissibility and its relation with bacterial microenvironment, caries index and maternal care. Sample: composed of 60 children of both genders, aging from one to three years, with their respective mothers. Employed techniques: PCR and Nested-PCR. Caries indexes: DMFT and dmft. Instruments: clinical exam and questionaires applied to mothers. Assessed: DMFT, dmft, oral hygine, care and affection habits. Results: There was a correlation between the presence or absence of Streptococcus mutans and sobrinus of mothers and respective children, being statistically different (P<0.05) both on dental plaque and saliva The caries index was equal to zero in 38.33% of children and 10% of mothers. Not flossing, tooth brushing twice a day, appointment with a dentist every 6 months and tasting their children’s food with the same spoon were the answers more frequently observed. PCR and Nested PCR techniques were adequate to detect Streptococcus mutans in saliva and dental plaque. The microorganisms’ detection was similar, both in saliva and dental plaque, and a correlation on the results of children and their respective mothers regarding presence/absence of S.sobrinus and S.mutans on either dental plaque or saliva was observed, confirming vertical transmission. A lower caries index was observed in children in relation to their respective mothers, although being higher than the WHO 2010 guidelines. The hygiene/affection habits related by mother were inadequate to their children... (Complete abstract click electronic access below)

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Favor, Helen McCusker. "Two Dimensional Analysis of Vibration Isolation of Rigid Bar Supported by Buckled or Pre-bent Struts." Thesis, Virginia Tech, 2004. http://hdl.handle.net/10919/36099.

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The purpose of this research is to study a new type of vibration isolator, utilizing the post-buckled stiffness of elastic struts (or columns). The advantage of the post-buckled state is that ideally it can support more static load with a relatively small static deflection than traditional vibration isolators such as springs or rubber mounts, but can also exhibit a low axial stiffness when dynamic excitation is introduced. Three models consisting of buckled or pre-bent struts serving as vibration isolators which support a rigid bar are examined in this research. The three cases studied are 1) two buckled struts supporting a symmetric rigid bar, 2) two buckled struts supporting an asymmetric rigid bar, and 3) two pairs of buckled struts with a bonded filler supporting a symmetric rigid bar. The models are subjected to a harmonic excitation at the base, and external damping is included. The struts in all cases are modeled as an elastica, and the boundary conditions are clamped/clamped for all cases. Because the purpose of the struts is to reduce unwanted vibrations, determining the displacement transmissibility of the system is the main goal of this research. Transmissibility versus frequency plots are generated for all cases, with varying parameters such as stiffness, damping, and location of center of mass, to determine how they affect the behavior of the struts. Models that produce a large range of frequencies at which the transmissibility is well below unity are the most effective. Vibration shapes are also determined for certain frequencies so that the physical behavior of the system can be studied.
Master of Science

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Sousa, Rosângela Ribeiro de. "Incidência de fusarium verticillioides em sementes de milho e métodos de inoculação em diferentes genótipos e estágios fenológicos." Universidade Federal do Tocantins, 2017. http://hdl.handle.net/11612/1020.

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A maioria dos patógenos responsáveis pelas principais doenças do milho (Zea mays L.) é transmitida pelas sementes, trazendo consequências como a podridão de sementes e o tombamento de plântulas, redução da germinação e do vigor, diminuindo assim a qualidade das sementes de milho. Este trabalho teve por objetivo avaliar a patogenicidade, transmissão e incidência de Fusarium verticilliodes em sementes de milho oriundas de espigas inoculadas com diferentes métodos. No presente trabalho foram realizados testes de detecção de F. verticillioides para confirmação da presença do patógeno nas plantas de milho inoculadas nas formas de spray, injetável e natural. Foi avaliada a porcentagem de emergência, qualidade fisiológica e sanitária de sementes de milho produzidas com diferentes graus de infecção por F. verticillioides, relacionando-se com a produtividade. Foi possível identificar a sensibilidade das técnicas de PCR, que amplificaram as concentrações de DNA testadas. A técnica de PCR utilizada foi capaz de detectar até 1% de infecção. Foi observado que as inoculações feitas nas espigas das plantas com spray resultaram em maior incidência do patógeno nas sementes quando comparada aos demais tratamentos. Os dez híbridos inoculados apresentaram incidência de F. verticillioides nas sementes que foram submetidas às três formas de inoculação. Quanto à emergência das plântulas verificou-se porcentagem superior à 90% em todos os híbridos estudados.
Most of the pathogens responsible for the main diseases of maize (Zea mays L.) are transmitted by seeds, with consequences such as seed rot and seedling tipping, germination and vigor reduction, thus reducing the quality of maize seeds. The objective of this work was to evaluate the pathogenicity, transmission and incidence of Fusarium verticilliodes in corn seeds from spikes inoculated with different methods. In the present work, Fusarium verticillioides detection tests were performed to confirm the presence of the pathogen in maize plants inoculated in spray, injectable and natural forms. The percentage of emergence, physiological and sanitary quality of maize seeds produced with different degrees of infection by F. verticillioides was evaluated, being related to productivity. The PCR technique used was able to detect up to 1% of infection. It was observed that the inoculations on the spikes of the spray plants resulted in a higher incidence of the pathogen in the seeds when compared to the other treatments. The ten inoculated hybrids showed incidence of F. verticillioides in the seeds that were submitted to all forms of inoculation. To verify the transmissibility of the seed pathogen to the plants, after extractions of leaf and stem tissues, DNA extraction analyzes with specific primer of F. verticillioides were made. Seedling emergence showed a percentage higher than 90% in all hybrids studied.

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Dunbar, K. E. A. "Molecular and conventional detection of the Burkholderia cepacia complex and other respiratory pathogens in cystic fibrosis : transmissibility, virulence factors and clinical outcome." Thesis, Queen's University Belfast, 2001. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.391109.

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Veith, Irina. "Lung Cancer On-Chip for Immunotherapy Response Profiling Apoptosis Mapping in Space and Time of 3D Tumor Ecosystems Reveals Transmissibility of Cytotoxic Cancer Death." Thesis, université Paris-Saclay, 2020. http://www.theses.fr/2020UPASL036.

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Le cancer du poumon non à petites cellules (CPNPC) est l'une des rares maladies tumorales, avec mélanome et carcinome vésical, pour lesquelles les médicaments immuno-oncologiques ont conduit à une révolution thérapeutique. Seuls 20 à 30% des patients atteints de CPNPC bénéficient de la monothérapie avec inhibiteurs des points de contrôle immunitaires (ICP) avec des réponses durables, tandis que les combinaisons ont conduit à réponse longue dans jusqu'à 40% des patients. Notre étude vise à mieux caractériser la modulation du microenvironnement tumoral lors d'un traitement ICP, plus ou moins une chimiothérapie concomitante, afin de guider des stratégies d'immunothérapie plus convaincantes. Inspiré par la technologie d'organes sur puce, nous avons reconstitué ex vivo un microenvironnement de tumeur pulmonaire immunocompétent simplifié en réalisant des co-cultures 3D dans des dispositifs microfluidiques. Cette approche nous a permis de réaliser une imagerie en direct et une quantification des effets de l'ICP sur l'écosystème tumoral. L’architecture de la puce se compose de trois micro-chambres parallèles, séparées par des micro-piliers qui permettent le confinement d'un hydrogel biomimétique dans le canal central par capillarité. En co-cultivant des cellules CPNPC et des lymphocytes T cytotoxiques autologues (récoltés à partir des TIL du même patient et amplifiés ultérieurement in vitro), nous pourrions récapituler, visualiser et quantifier une activité cytotoxique efficace et spécifique des cellules T contre les cellules cancéreuses autologues. Pour cela, nous avons développé un nouvel algorithme qui pourrait localiser les cellules cancéreuses et, grâce à un rapporteur fluorescent de l'activité caspase, mesurer leur mort d'une manière spécifique au temps et à l'espace. Dans ces co-cultures 3D, l'activité cytotoxique des cellules T a été renforcée par le traitement avec l'inhibiteur PD-1 et l'inhibiteur PD-L1, reconstituant ainsi sur puce une réponse ICI. De plus, cette méthode nous a permis d'extraire un paramètre, le potentiel d'induction de la mort, qui estime mathématiquement la «contagiosité de la mort» en calculant la proximité dans l'espace et le temps des signaux de mort. Fait intéressant, cette analyse nous a révélé que la mort des cellules cancéreuses causée par la chimiothérapie ou par les cellules T cytotoxiques est contagieuse, alors que dans les conditions témoins, la mort des cellules cancéreuses est stochastique. Cette observation peut avoir des implications biologiques et cliniques, par exemple en ce qui concerne « l'effet spectateur », observé après un traitement de radiothérapie. De plus, afin d'avoir un aperçu moléculaire de l'impact de la co-culture sur les cellules T, en présence ou en l'absence d'ICI, nous avons analysé par cytométrie de flux l'expression de plusieurs marqueurs de cellules T. Après 3 jours de co-culture sur puce, les lymphocytes T ont montré une expression accrue des marqueurs d'activation, tels que CD69 et CD25, ainsi qu'une augmentation de l’expression des marqueurs d'épuisement, notamment PD-1, TIGIT, TIM-3, LAG- 3, CD137 et OX-40. Le couplage de l'analyse d'image et de l'étude de la plasticité des lymphocytes T, nous a permis d'associer pour la première fois l'activité cytotoxique finement quantifiée des lymphocytes T avec leur statut d'activation / épuisement et de décrire un phénotype réactif aux immunothérapies. Dans cette thèse, nous avons démontré que la tumeur-sur-puce peut être exploité pour évaluer l'efficacité des inhibiteurs de points de contrôle immunitaires, potentiellement pour déterminer l'effet de médicaments combinés et enfin pour étudier les mécanismes de résistance primaire des cellules cancéreuses
Non-small cell lung cancer (NSCLC) is one of the few tumor diseases, with melanoma and vesical carcinoma, for which immuno-oncology drugs led to a therapeutic revolution. Only 20 to 30% of the NSCLC patients benefit from immune checkpoint inhibitors (ICI) monotherapy with durable responses, while combinations led up to 40% of long responder patients. Our study aims to better characterize the modulation of the tumor microenvironment upon ICI treatment, plus or minus concurrent chemotherapy, in order to guide more compelling immunotherapy strategies. Inspired by the organ-on-a-chip technology, we implemented the reconstitution ex vivo of a simplified immunocompetent lung tumor microenvironment by performing 3D co-cultures in microfluidic devices. This approach allowed us to perform live-imaging and quantification of the effects of ICI on the tumor ecosystem.The design of the chip consists of three parallel micro-chambers, separated by micro-pillars that allow the confinement of a biomimetic hydrogel in the central channel by capillarity. By co-culturing autologous NSCLC cells and cytotoxic T lymphocytes (harvested from the TILs of the same patient and furtherly amplified in vitro) we could recapitulate, visualize and quantify an efficient and specific cytotoxic activity of the T cells against the autologous cancer cells. For this purpose, we developed a novel algorithm that could localize the cancer cells and, thanks to a fluorescent reporter of the caspase activity, measure their death in a time- and space-specific manner. In these 3D co-cultures the cytotoxic activity of T cells was enhanced by the treatment with PD-1 inhibitor and PD-L1 inhibitor, therefore reconstituting on-chip an ICI response. Furthermore, this method allowed us to extract a parameter, the potential of death induction, which mathematically estimates the “contagiousness of death” by computing the proximity in space and time of death signals. Interestingly, this analysis revealed us that the death of cancer cells caused by either chemotherapy or cytotoxic T cells is contagious, whereas in control conditions the cancer cells death is stochastic. This observation may have biological and clinical implications, for instance regarding the bystander effect, observed after radiotherapy treatment. Furthermore, in order to have a molecular insight on the impact of the co-culture on T cells, in presence or absence of ICI, we analyzed by flow cytometry the expression of several T cell markers. After 3 days of co-culture on chip, the T cells showed an increased expression of activation markers, such as CD69 and CD25, as well as an increased expression of exhaustion markers, notably PD-1, TIGIT, TIM-3, LAG-3, CD137 and OX-40. The coupling of image analysis and the study of T cell plasticity, allowed us to associate for the first time the finely quantified cytotoxic activity of the T cells and their activation/exhaustion status and describe a responsive phenotype to immunotherapies. In this thesis, we demonstrated that the tumor-on-chip is suitable to evaluate the efficacy of immune checkpoint inhibitors, to potentially assess the effect of combined drugs and to study the mechanisms of cancer cell primary resistance

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Franchini, Danilo. "ANÁLISE DO NÍVEL DE VIBRAÇÕES NOS ASSENTOS DE TRATORES AGRÍCOLAS." Universidade Federal de Santa Maria, 2007. http://repositorio.ufsm.br/handle/1/7590.

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Nowadays, whole-body vibration is widely recognized as risk factor for worker all around the world. Most of published works on this subject was developed in main research centers. The aims of this study were (1) to determine the vertical whole-body vibration levels on the tractor seat, (2) to determine the combination influence between three tire inflation pressures and two travel speed in the whole-body vibration, (3) to characterize the vertical whole-body vibration high level in one-third-octave band, (4) to determine the transmissibility between the seat and the seat support, (5) to compare the values with ISO 2631 (1997) Standard. A vertical whole-body vibration levels field measurement was accomplished with a 65 kW tractor and a seeder-fertilizer. Three tire inflation pressures P1 = 179 kPa, P2 = 138 kPa and P3 = 96 kPa and two travel speed V1 = 4,5 km/h and V2 = 7 km/h were used in this study. The results revealed that (1) the lowest acceleration weighting was 0,68 m/s² (P1 x V1) and de highest acceleration weighting was 3,32 m/s² to (P1 x V2), (2) the whole-body vibrations, the travel speed, the tire inflation pressure and it s interaction have influenced on the vertical whole-body vibration, (3) the vertical whole-body vibration high level in one-third-octave band was 4 at 8 Hz by combination (P1, P2 and P3) with (V2), excepted for (P2 x V2) by 5 Hz, (4) the lowest SEAT% weighting by combination (V1) with (P1) and (P2), (5) the pressure and speed combination resulted in whole-body vibrations levels which characterize the operator seat from fairly uncomfortable to extremely uncomfortable. The best scenario was (P1 x V1), because the tractor operator was submitted to acceptable vertical whole-body vibration levels.
Hoje em dia, vibrações ocupacionais são amplamente reconhecidas como fator de risco para os trabalhadores em todo o planeta. A maioria dos trabalhos publicados sobre este assunto são desenvolvidos em grandes centros de pesquisa. Os objetivos deste estudo foram (1) determinar os níveis de vibrações verticais no assento do trator, (2) determinar a influência da combinação entre três pressões de insuflagem e duas velocidades de deslocamento nas vibrações ocupacionais, (3) caracterizar a faixa de freqüência que apresenta os maiores picos de vibração vertical no assento do operador do trator, (4) determinar os valores da transmissibilidade entre o suporte do assento e o assento, (5) comparar os resultados encontrados com os valores exigidos com a norma técnica ISO 2631 (1997). Foram realizadas medições de vibrações ocupacionais (verticais) a campo com um trator de 65 kW e uma máquina de semeadura e adubação. Três pressões de insuflagem P1 = 179 kPa, P2 = 138 kPa e P3 = 96 kPa e duas velocidades de deslocamento V1 = 4,5 km/h e V2 = 7 km/h foram usadas neste estudo. Os resultados revelaram que (1) o mais baixo valor de MAPG foi de 0,68 m/s² para (P1 x V1) e o mais alto valor de MAPG foi de 3,32 m/s² para (P1 x V2), (2) as pressões de insuflagem, as velocidades de deslocamento e a sua interação influenciaram nas vibrações ocupacionais, (3) as faixas de freqüência que apresentaram os maiores picos de vibração foram de 4 a 8 Hz na combinação entre as três pressões com a velocidade (V2), exceto para (P2 x V2) na freqüência de 5 Hz que ficou abaixo do limite de 8 horas de exposição, (4) o menor valor de SEAT% foi na combinação entre a velocidade (V1) com as pressões (P1) e (P2), (5) a combinação das pressões com as velocidades resultou em níveis de vibrações ocupacionais que caracterizam o assento do operador de razoavelmente desconfortável até extremamente desconfortável. O melhor cenário foi (P1 x V1), pois o operador esteve exposto a magnitudes de vibrações aceitáveis.

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35

Marafiotti, Graziela de Almeida Prado e. Piccino. "Detecção da transmissão vertical do S. mutans e S. sobrinus e relação com o micro-ambiente bacteriano, índice de cárie e cuidados maternos /." Botucatu : [s.n.], 2009. http://hdl.handle.net/11449/102649.

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Resumo: A cárie dentária pediátrica continua sendo uma doença significativa em países em desenvolvimento. A presença de microrganismos cariogênicos na saliva materna pode favorecer a contaminação de seu filho. O desenvolvimento das lesões é fortemente dependente do momento em que ocorreu a infecção; quando precoce, a prevalência de cárie é maior. Detectar a transmissão vertical do S. mutans e S. sobrinus e relação com o micro ambiente bacteriano, índice de cárie e cuidados maternos. Amostra: 60 crianças, ambos os gêneros, de um a três anos de idade e suas respectivas mães. Técnicas utilizadas: PCR e Nested- PCR. Indices de cárie: CPO-D e ceo. Instrumentos: exame clínico e questionário aplicado às mães. Registrou-se: ceo, CPO-D, higiene bucal, cuidados e hábitos de carinho. Resultados. Houve concordância de ausência e de presença de Streptococcus mutans e sobrinus entre mães e filhos, com diferença estatísticamente significante (p<0,05), tanto na placa como na saliva; índices de cárie igual a zero somente em 38,33% das crianças e 10% das mães; maior freqüência de respostas das mães para a questão sobre o não uso de fio dental, duas escovações diárias, visita ao dentista com intervalo de seis meses e prova do alimento do filho com a própria colher. As técnicas PCR e Nested PCR se mostraram adequadas para a detecção de Streptococcus. Houve concordância dos resultados dos filhos e suas respectivas mães quanto à presença/ausência de microrganismos S. sobrinus e S. mutans na placa e saliva, sugerindo a transmissibilidade vertical. Detectou-se um menor índice de cárie dos filhos em relação às suas mães. O Índice de cárie das crianças foi superior ao esperado pela OMS para 2010 e os hábitos de higiene/carinhos relatados pelas mães eram inadequados para com seus filhos... (Resumo completo, clicar acesso eletrônico abaixo)
Abstract: Dental caries in children is still an expressive disease .The presence of cariogenic microorganisms on maternal saliva might favor contamination of their children. The development of caries lesions is strongly related to the time when infection takes place; the sooner, the higher the caries prevalence. To detect S.mutans and S.sobrinus vertical transmissibility and its relation with bacterial microenvironment, caries index and maternal care. Sample: composed of 60 children of both genders, aging from one to three years, with their respective mothers. Employed techniques: PCR and Nested-PCR. Caries indexes: DMFT and dmft. Instruments: clinical exam and questionaires applied to mothers. Assessed: DMFT, dmft, oral hygine, care and affection habits. Results: There was a correlation between the presence or absence of Streptococcus mutans and sobrinus of mothers and respective children, being statistically different (P<0.05) both on dental plaque and saliva The caries index was equal to zero in 38.33% of children and 10% of mothers. Not flossing, tooth brushing twice a day, appointment with a dentist every 6 months and tasting their children's food with the same spoon were the answers more frequently observed. PCR and Nested PCR techniques were adequate to detect Streptococcus mutans in saliva and dental plaque. The microorganisms' detection was similar, both in saliva and dental plaque, and a correlation on the results of children and their respective mothers regarding presence/absence of S.sobrinus and S.mutans on either dental plaque or saliva was observed, confirming vertical transmission. A lower caries index was observed in children in relation to their respective mothers, although being higher than the WHO 2010 guidelines. The hygiene/affection habits related by mother were inadequate to their children... (Complete abstract click electronic access below)
Orientador: Maria Inês de Moura Campus Pardini
Coorientador: Nidia Alice Pinheiro
Banca: Solange O. Braga Franzolin
Banca: Leila Maria Vieira
Banca: Izabel M. M. Carvalho
Banca: Ana Lucia Capelozza
Doutor

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36

DeShaw, Jonathan. "New methodologies for evaluating human biodynamic response and discomfort during seated whole-body vibration considering multiple postures." Diss., University of Iowa, 2013. https://ir.uiowa.edu/etd/4611.

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The lack of adequate equipment and measurement tools in whole-body vibration has imposed significant constraints on what can be measured and what can be investigated in the field. Most current studies are limited to single direction measurements while focusing on simple postures. Besides the limitation in measurement, most of the current biomechanical measures, such as the seat-to-head transmissibility, have discrepancies in the way they are calculated across different labs. Additionally, this field lacks an important measure to quantify the subjective discomfort of individuals, especially when sitting with different postures or in multiple-axis vibration. This work begins by explaining discrepancies in measurement techniques and uses accelerometers and motion capture to provide the basis for more accurate measurement during single- and three-dimensional human vibration responses. Building on this concept, a new data collection method is introduced using inertial sensors to measure the human response in whole-body vibration. The results indicate that measurement errors are considerably reduced by utilizing the proposed methods and that accurate measurements can be gathered in multiple-axis vibration. Next, a biomechanically driven predictive model was developed to evaluate human discomfort during single-axis sinusoidal vibration. The results indicate that the peak discomfort can be captured with the predictive model during multiple seated postures. The predictive model was then modified to examine human discomfort to whole-body vibration on a larger scale with random vibrations, multiple postures, and multiple vibration directions. The results demonstrate that the predictive measure can capture human discomfort in random vibration and during varying seated postures. Lastly, a new concept called effective seat-to-head transmissibility is introduced, which describes how to combine the human body's biodynamic response to vibration from multiple directions. This concept is further utilized to quantify the human response using many different vibration conditions and seated postures during 6D vibration. The results from this study demonstrate how complicated vibrations from multiple-input and multiple-output motions can be resolved into a single measure. The proposed effective seat-to-head transmissibility concept presents an objective tool to gain insights into the effect of posture and surrounding equipment on the biodynamic response of the operators. This thesis is timely as advances in seat design for operators are increasingly important with evolving armrests, backrests, and seat suspension systems. The utilization of comprehensive measurement techniques, a predictive discomfort model, and the concept of effective seat-to-head transmissibility, therefore, would be beneficial to the fields of seat/equipment design as well as human biomechanics studies in whole-body vibration.

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Silva, Lucas de Haro. "Análise de transmissibilidade do modelo de Zener com parâmetros não lineares /." Bauru, 2019. http://hdl.handle.net/11449/191474.

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Orientador: Paulo José Paupitz Gonçalves
Resumo: O modelo de Zener, também conhecido como o modelo SLS, do inglês (Standard Linear Solid), é um modelo simples que descreve o comportamento de um material viscoelástico como isolador de vibração, utilizando uma combinação linear de molas e amortecedores para representar componentes elásticos e viscosos, respectivamente. Sabe-se que, o modelo mais semelhante de Maxwell, que é uma mola em série com um amortecedor, e o modelo de Kelvin-Voigt, que é uma mola em paralelo com um amortecedor, são utilizados. No entanto, estes modelos são muitas vezes insuficientes para representar tal comportamento desejado, o modelo de Maxwell não descreve a fluência ou recuperação, e o modelo de Kelvin-Voigt não descreve o stress e o relaxamento. O SLS é o modelo mais simples, que prevê dois fenômenos, com isso em mente, esta tese propõe a investigação do modelo de amortecimento de Zener substituindo as molas simples por molas não lineares (mola Duffing), no que diz respeito ao comportamento de isolamento de vibração, mostrando as curvas de transmissibilidade para vários valores de parâmetros. São utilizados métodos analíticos aplicáveis a sistemas não lineares, bem como método numérico para realizar análises de transmissibilidade do modelo de Zener e também o desenvolvimento de um aparato experimental que representa o modelo de isolador de vibração de Zener, essencial para um entendimento substancial dos fenômenos envolvidos. O objetivo principal da tese é investigar oportunidades de melhoria de i... (Resumo completo, clicar acesso eletrônico abaixo)
Abstract: The Zener model, also known as the solid linear standard model (SLS), is a simple model that describes the behavior of a viscoelastic material as a vibration isolator, using a linear combination of springs and dampers to represent elastic and viscous components , respectively. Often the most similar Maxwell model, which is a spring in series with a damper, and the Kelvin-Voigt model, which is a spring in parallel with a damper, are used. However, these models are often insufficient to represent such behavior, the Maxwell model does not describe fluency or recovery, and the Kelvin-Voigt model does not describe stress and relaxation. The SLS is the simplest model, which predicts two phenomena, with this in mind, this thesis proposes the investigation of the Zener damping model replacing the simple springs with non-linear springs (Duffing spring), with respect to the vibration isolation behavior, showing the transmissibility curves for various parameter values . Analytical methods will be used for non-linear systems, as well as a numerical method to carry out Zener model transmissibility analyzes, as well as the development of an experimental apparatus that represents Zener’s vibration isolator model, which is essential for a substantial understanding of the phenomena involved. The main objective of the thesis is to investigate opportunities for improvement of mechanical isolators when designed to act in dynamic bands with non-linear responses.
Doutor

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GRIMPAMPI, ELENI. "An integrated approach to whole-body vibration." Doctoral thesis, Università degli Studi di Roma "Tor Vergata", 2009. http://hdl.handle.net/2108/897.

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Obiettivo di questa tesi è la determinazione e quantificazione degli effetti della whole-body vibration al corpo umano, in termini di consumo energetico, tramite un approccio globale e integrato. L’obiettivo è ottenuto considerando il corpo umano come una struttura organica complessa. Allo scopo di comprendere come questo risponda alle vibrazioni verticali, il consumo energetico del corpo umano è stato misurato per mezzo della variazione della temperatura superficiale con tecniche di misurazione a termografia infrarossa. Lo spostamento dei muscoli invece con il sistema di analisi di movimento Vicon MX. Infine, per quanto riguarda il consumo di ossigeno con il sistema telemetrico Cosmed K4. Il primo passo è stato l’istituzione di un protocollo appropriato che soddisfi l’obiettivo di questo studio. Infatti, la mancanza di coerenza nei protocollo di whole-body vibration che si trovano allo stato dell’arte, ha reso essenziale l’istituzione di un apposito protocollo, ed a questo scopo è stata definita la struttura dell’esperimento. Di conseguenza, è stata avviata una serie di prove per esaminare la risposta del corpo umano alle vibrazioni verticali, cambiando la durata e la frequenza della vibrazione, nonché la durata del periodo di riposo. In totale, quattro persone in piedi sono state sottoposte a vibrazioni verticali, in una pedana vibrante, a frequenze da 20 a 50 Hz. Dopo l’instaurazione del protocollo finale, sono stati avviate una serie di prove di laboratorio. In particolare, sono state scelte tre frequenze per le vibrazioni: 20, 30 e 45 Hz. I risultati ottenuti più interessanti di questo studio, riguardano il consumo di ossigeno, la temperatura superficiale e i coefficienti di trasmissibilità dell’accelerazione.
The objective of this thesis is to determine and quantify the effects of whole-body vibration to the human body in terms of energy expenditure, by means of a global and integrated approach. This objective is attained by considering the human body as a complex organic structure. In order to understand how it responds to vertical vibrations, the energy expenditure of the human body was measured by means of the variation in superficial temperature with the aid of infrared thermography, the displacement of the muscles with the aid of the Vicon MX motion analysis system and the oxygen uptake with the aid of the Cosmed K4 telemetric system. The establishment of an appropriate protocol which satisfies the aim of this study was the first goal. The lack of consistency in whole-body vibration protocols in the current published studies makes the establishment of an appropriate protocol essential, and in this sense, an experiment setup was implemented. Therefore, a series of experiments was conducted to examine the response of the human body to vertical vibrations, changing the duration and the frequency of vertical vibration, and the duration of rest period. A number of four persons were subjected to vertical vibrations on a vibrating table in a standing position at a frequency ranging from 20 to 50 Hz. After the establishment of the final protocol, a series of laboratory experiments took place. Three different vibration frequencies were chosen: 20, 30 and 45 Hz corresponding to three different tests. The most interesting findings regard the oxygen consumption, the superficial temperature evolution, and the transmissibility coefficients for the acceleration.

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Al, Jailawi Samer Saadi Hussein. "Damage detection using angular velocity." Diss., University of Iowa, 2018. https://ir.uiowa.edu/etd/6539.

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The present work introduces novel methodologies for damage detection and health monitoring of structural and mechanical systems. The new approach uses the angular velocity inside different mathematical forms, via a gyroscope, to detect, locate, and relatively quantify damage. This new approach has been shown to outperform the current state-of-the-art acceleration-based approach in detecting damage on structures. Additionally, the current approach has been shown to be less sensitive to environmental acoustic noises, which present major challenges to the acceleration-based approaches. Furthermore, the current approach has been demonstrated to work effectively on arch structures, which acceleration-based approaches have struggled to deal with. The efficacy of the new approach has been investigated through multiple forms of structural damage indices. The first methodology proposed a damage index that is based on the changes in the second spatial derivative (curvature) of the power spectral density (PSD) of the angular velocity during vibration. The proposed method is based on the output motion only and does not require information about the input forces/motions. The PSD of the angular velocity signal at different locations on structural beams was used to identify the frequencies where the beams show large magnitude of angular velocity. The curvature of the PSD of the angular velocity at these peak frequencies was then calculated. A damage index is presented that measures the differences between the PSD curvature of the angular velocity of a damaged structure and an artificial healthy baseline structure. The second methodology proposed a damage index that is used to detect and locate damage on straight and curved beams. The approach introduces the transmissibility and coherence functions of the output angular velocity between two points on a structure where damage may occur to calculate a damage index as a metric of the changes in the dynamic integrity of the structure. The damage index considers limited-frequency bands of the transmissibility function at frequencies where the coherence is high. The efficacy of the proposed angular-velocity damage-detection approach as compared to the traditional linear-acceleration damage-detection approach was tested on straight and curved beams with different chord heights. Numerical results showed the effectiveness of the angular-velocity approach in detecting damage of multiple levels. It was observed that the magnitude of the damage index increased with the magnitude of damage, indicating the sensitivity of the proposed method to damage intensity. The results on straight and curved beams showed that the proposed approach is superior to the linear-acceleration-based approach, especially when dealing with curved beams with increasing chord heights. The experimental results showed that the damage index of the angular-velocity approach outweighed that of the acceleration approach by multiple levels in terms of detecting damage. A third methodology for health-monitoring and updating of structure supports, which resemble bridges’ bearings, is introduced in this work. The proposed method models the resistance of the supports as rotational springs and uses the transmissibility and coherence functions of the output response of the angular velocity in the neighborhood of the bearings to detect changes in the support conditions. The proposed methodology generates a health-monitoring index that evaluates the level of deterioration in the support and a support-updating scheme to update the stiffness resistance of the supports. Numerical and experimental examples using beams with different support conditions are introduced to demonstrate the effectiveness of the proposed method. The results show that the proposed method detected changes in the state of the bearings and successfully updated the changes in the stiffness of the supports.

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Packer, Sergio Paulo. "Estudo sobre a influência da vibração na execução de tarefas de pilotos de aeronaves." Universidade de São Paulo, 2008. http://www.teses.usp.br/teses/disponiveis/3/3150/tde-02022009-180004/.

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Esse trabalho visa estudar a influência da vibração no desempenho de tarefas de pilotos de aeronaves. Para o seu desenvolvimento, foi montada uma bancada usando um assento de aeronave para avaliar a transmissibilidade da vibração vertical para os pilotos e verificar se níveis elevados de aceleração, como no caso de falha da turbina, podem prejudicar sua habilidade em desempenhar tarefas de leitura, escrita e digitação. Todos os experimentos foram realizados com sucesso, comprovando grande parte dos estudos anteriores sobre o assunto. Ainda são apresentadas comparações relacionando os mesmos níveis de aceleração usados no teste de transmissibilidade, com as normas ISO 2631-1 e ANSI S3.18 para avaliação da exposição humana à vibração de corpo inteiro, que são as mais apropriadas para a correlação com o mundo aeronáutico.
This work aims to study the influence of vibration in aircraft pilots task performance. For the study development, it was assembled a rig test using an aircraft pilot seat, in order to evaluate the transmissibility of vertical vibration to the pilots and to verify if high acceleration levels, as in the case of engine failure, are of significance to the pilots ability in performing tasks such as reading, writing and typing. All the experiments were accomplished successfully, confirming most of early studies about the subject. Comparisons are also presented, relating the same acceleration levels used in the transmissibility test with ISO 2631-1 and ANSI S3.18 standards for evaluation of human exposure to whole-body vibration which are the most appropriated for correlation with the aeronautical world.

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Do, Van Dong. "Usinage à grande vitesse efficace basé sur l'identification opérationnelle du comportement dynamique et l'optimisation du support de pièce." Thesis, Université Clermont Auvergne‎ (2017-2020), 2020. http://www.theses.fr/2020CLFAC036.

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L’usinage à grande vitesse joue aujourd’hui un rôle très important dans l’industrie mécanique. Cependant, les phénomènes vibratoires en usinage peuvent être néfastes à la qualité des pièces usinées, à la productivité et à la durabilité des accessoires, etc. La maîtrise du comportement dynamique du système couplé (machine-outil/broche/outil/pièce/porte-pièce) est la clé primordiale pour la réussite de l’usinage à grande vitesse. Le premier objectif de la thèse a consisté à appliquer des techniques existantes d’identification modale opérationnelle et à proposer de nouvelles techniques d’identification mieux adaptées en tenant compte des spécificités de l’usinage à savoir : la présence des harmoniques très prépondérants, l’excitation aléatoire non contrôlée et non-mesurée, et les réponses seules enregistrées. Trois nouvelles procédures d’identification modale opérationnelle ont été proposées : la méthode de transmissibilité (PSDTM-SVD) (i) combinée avec les valeurs de kurtosis et les histogrammes, (ii) ou hybridée avec les fonctions d’autocorrélation, (iii) et la nouvelle méthode SCA-FDD basée sur la séparation aveugle de sources. L’efficacité des méthodes proposées a été validée par des exemples numériques et un test expérimental. Le deuxième objectif de la thèse a consisté à proposer une nouvelle conception du support de pièce en utilisant des matériaux innovants, afin de rendre le comportement dynamique optimal vis-à-vis de la stabilité d’usinage. Pour augmenter les performances d’usinage, le nouveau support en matériau composite doit posséder une raideur au moins égale à celle du support existant en aluminium tout en ayant un taux d’amortissement plus élevé. Un nouveau composite stratifié hybride renforcé par des fibres de carbone et des fibres de lin est alors proposé. Cette combinaison permet d’allier les avantages des deux types de fibres dans un même composite. Des supports de pièce en composite stratifié hydride carbone-lin avec différentes séquences d’empilement ont été fabriqués pour des essais de validation. Dans le cas d’usinage avec les supports de pièce en composite, la stabilité d’usinage est fortement augmentée par rapport au support initial en aluminium. Parmi les différentes séquences d’empilement, le support de pièce en composite hybride carbone-lin [C6/L8/C6] est la solution optimale en termes de performance d’usinage et d’impact environnemental. Cette solution permet d’augmenter la stabilité d’usinage de 283 % avec un taux de fibres végétales de 14 %
High-speed machining plays a very important role in the engineering industry today. However, vibration phenomena during machining process can be detrimental to the quality of machined workpiece, the productivity and the durability of accessories, etc. Mastering the dynamic behavior of the coupled system (machine tool/spindle/tool/workpiece/workpiece holder) is the primordial key to successful high speed machining. The first objective of the thesis consisted in applying existing techniques of operational modal identification and proposing new identification techniques better adapted to take into account the specificities of machining: the presence of very predominant harmonics, the uncontrolled and unmeasured random excitation, and responses only recorded. Three new operational modal identification procedures have been proposed: the transmissibility method (PSDTM-SVD) (i) combined with kurtosis values and histograms, (ii) or hybridized with autocorrelation functions, (iii) and the new SCA-FDD method based on blind source separation. The effectiveness of the proposed methods has been validated by numerical examples and an experimental test. The second objective of the thesis was to propose a new design of the workpiece support using innovative materials, in order to make the dynamic behavior optimal with respect to machining stability. To increase the machining performance, the new composite workpiece holder must have a stiffness at least equal to that of the initial aluminum workpiece holder while having a higher damping ratio. A new hybrid composite laminate reinforced by carbon and flax fibers is then proposed. This combination enables to combine the advantages of two fiber types in a composite. Workpiece holders in carbon-flax hybrid composite laminates with different stacking sequences were fabricated for validation tests. In the case of machining with the composite workpiece holders, the machining stability is greatly increased compared to the initial aluminum workpiece holder. Among the different stacking sequences, the carbon-flax hybrid composite workpiece holder [C6/L8/C6] is the optimal solution in terms of machining performance and environmental impact. This solution increases machining stability by 283 % with a vegetable fiber volume ratio of 14 %

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Quartaroli, Matheus Mikael. "Análise dinâmica de um sistema de atuação eletromecânica em mecanismo de suspensão mecânica para isolamento de vibrações." Universidade Estadual Paulista (UNESP), 2018. http://hdl.handle.net/11449/153314.

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Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)
Esse trabalho buscou investigar os comportamentos dinâmicos de uma suspensão eletromecânica. Para a configuração dessa suspensão substitui-se o amortecedor viscoso convencional por um amortecedor do tipo eletromecânico. O amortecedor eletromecânico é formado por um transdutor de imã permanente e bobina móvel, no qual se acopla ao sistema mecânico com o eletromagnético. Nos terminais da bobina é introduzido um circuito elétrico RLC ligados em série. Para modelagem e a obtenção das equações dinâmica que descrevem seu movimento utilizou-se o método de Lagrange, que utiliza expressões de energia. Os modelos abordam absorvedores utilizados na indústria automobilística. No trabalho, primeiramente foi investigado a capacidade dos parâmetros elétricos no comportamento do sistema, e verificou-se a influência que a resistência elétrica e a capacitância tem em relação ao deslocamento da massa suspensa de um veículo. Foi realizada, através da função transferência, uma análise da quantidade de energia obtida no sistema elétrico para valores diferentes de resistência elétrica e em comparação foi verificado o ganho da massa suspensa para um movimento harmônico sofrido pela base. Por fim, investigou-se as potências geradas no circuito elétrico e o fator de potência para diferentes valores de capacitância. E também apurou a influência da resistência elétrica na produção de potência ativa. Os resultados mostraram a influência dos parâmetros elétricos no comportamento dinâmico do sistema e na geração de potência elétrica, assim através de um controle feito nesses parâmetros pode-se encontrar faixas no qual reduz a transmissibilidade de deslocamento para os ocupantes de um veículo e geram uma alta potência elétrica em que possa ser armazenada e utilizada posteriormente.
This work sought to investigate the dynamic behavior of an electromechanical suspension. For the configuration of this suspension it replaces the conventional viscous damper with a shock absorber of the electromechanical type. The electromechanical damper is formed by a permanent magnet transducer and mobile coil, in which it couples the mechanical system with the electromagnetic. At the terminals of the coil is introduced an RLC electric circuit connected in series. For the modeling and the obtaining of the dynamic equations that describe its movement was uses the Lagrange method, that uses expressions of conservation of energy. The models approach in a simplified way the absorbers used in the automotive industry. In the work, it was first investigated the influence of the electrical parameters on the behavior of the system, it was verifies the power of the electrical resistance and the capacitance have in relation to the displacement of the suspended mass of a vehicle. It was performed, through the transfer function, an analysis of the amount of energy obtained in the electrical system is performed for different values of electrical resistance and in comparison it was verifies the gain of the suspended mass for a harmonic movement suffered by the base. Finally, we investigated the powers generated in the electric circuit and the power factor for different capacitance values. It also determined the influence of electrical resistance on the production of active power. The results showed the influence of the electrical parameters on the dynamic behavior of the system and the generation of electric power, so through a control made in these parameters can be found tracks in which reduces the transmissibility of displacement for the occupants of a vehicle and generate a high electrical power where it can be stored and used later.

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43

Mhlambi, Sanelisiwe. "A Systematic Evaluation of Fault Seal Integrity in the southern Pletmos Basin, offshore South Africa: A 3D Multidisciplinary Modelling Approach." University of the Western Cape, 2017. http://hdl.handle.net/11394/6357.

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Magister Scientiae - MSc (Earth Science)
The syn-rift succession encompasses the primary exploration target in the southern Pletmos Basin. Several fault-bounded structural traps that contain gas accumulations have been discovered within this succession. Likewise, ubiquitous residual gas shows have been encountered in most drilled wells. Yet, the impact of faults on fluid flow is poorly understood. Therefore, this study aspires to predict, and where possible, quantify fault seal integrity and sealing capacities of some of the major prospect-bounding faults. A multi-disciplinary research strategy was employed in order to fulfil the study objectives. Fault mapping and geo-cellular modelling using geostatistical algorithms were undertaken to provide the basic geometric and structural input for more advanced fault seal analysis applications. Juxtaposition analysis was carried out to identify zones with a high probability to seal (or leak) and as the first-order tool for predicting fault seal potential. Threshold pressures, hydrocarbon column heights, cross-fault permeability and transmissibility were used to estimate the sealing capacities of the faults. In addition to juxtaposition and customary fault-rock properties, the study also analysed parameters that can be deemed to be representative of cross-fault fluid flow (i.e. effective cross-fault permeability and transmissibility; ECFP and ECFT). Finally, modelling of the geo-history facilitated the validation of the properties that underpinned fault seal analysis studies. The Ga-Q and proposed Ga-K prospects along with their main bounding faults formed the foci of the fault seal analysis results. The analysed faults showed excellent initial sealing potential due to either favourable juxtaposition or shale gouge development. Nonetheless, predicted hydrocarbon column heights and threshold pressures were low suggesting that the seal integrity of the analysed faults is predisposed to failure. In addition, high predicted fault permeability and transmissibility values signify the presence of open and permeable fracture networks within the fault zones. Thus, it is proposed that the faults are very likely to have leaked during hydrocarbon migration and filling of traps resulting in empty or under-filled hydrocarbon reservoirs.

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44

Wang, Shuo. "Control of a Uni-Axial Magnetorheological Vibration Isolator." University of Toledo / OhioLINK, 2011. http://rave.ohiolink.edu/etdc/view?acc_num=toledo1302200947.

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45

Novell, Sara T. "Design of Structural Stand for High-Precision Optics Microscopy." DigitalCommons@CalPoly, 2020. https://digitalcommons.calpoly.edu/theses/2132.

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Lawrence Livermore National Lab (LLNL) is home to the National Ignition Facility (NIF), the world’s largest and most energetic laser. Each of the 192 beamlines contains dozens of large optics, which require offline damage inspection using large, raster-scanning microscopes. The primary microscope used to measure and characterize the optical damage sites has a precision level of 1 µm. Mounted in a class 100 clean room with a raised tile floor, the microscope is supported by a steel stand that structurally connects the microscope to the concrete ground. Due to ambient vibrations experienced in the system, the microscope is only able to reliably reach a 10-µm level of precision. As NIF’s technology advances, there is a need to both increase optic measurement throughput and to measure damage sites at a higher level of precision. As a result, there is to be another microscope mounted into another clean room lab at LLNL. To assure the microscope can meet its specified level of precision, the stand on which it is mounted was designed to meet the rigorous Environmental Vibrational Criteria standards, or VC curves. Through the collection of random vibrational data using accelerometers and Power Spectral Density (PSD) analysis, the stand was designed to meet the VC-C curve requirement of velocities below 12.5 µm/sec. Furthermore, the stand design was optimized to avoid resonance at common vibrational signatures throughout the frequency spectrum, placing its first natural frequency at a sufficiently high level to minimize amplification.

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GOROG, SYLVIE. "Transmissibilite acoustique en milieu absorbant. Approche energetique." Palaiseau, Ecole polytechnique, 1995. http://www.theses.fr/1995EPXX0021.

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Dans le domaine de recherche pour l'amelioration de l'isolation phonique et vibratoire, ce travail a pour objet l'analyse de phenomenes d'absorption efficaces pour reduire, voire annuler, la propagation des ondes dans un milieu solide. L'etude examine la transmissibilite acoustique des materiaux utilises comme milieux absorbants dans le cadre rigoureux de la thermodynamique des processus irreversibles. Cette approche energetique generale permet d'evaluer la dissipation generee au cours de la propagation pour differents comportements dynamiques. La modelisation de cette propagation dans le materiau etudie s'effectue a une echelle mesoscopique avec une representation continue viscoelastique ou elastoplastique en decrivant le mouvement propage par des ondes harmoniques planes ou sous forme d'une surface de discontinuite mobile d'acceleration. L'analyse explicite les parametres dissipatifs et conduit a la definition d'une dissipation dynamique intrinseque caracterisant l'absorption acoustique. Cette etude identifie les mecanismes dissipatifs preponderants a des mouvements massiques internes et donne une interpretation physique des phenomenes selon la microstructure traversee

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47

Soto, Delgado Gerardo Brayan, and Silva Rodrigo Alberto Vente. "Reducción del desplazamiento relativo de la base en estructuras con aisladores sismicos mediante el concepto de transmisibilidad relativa." Bachelor's thesis, Universidad Peruana de Ciencias Aplicadas (UPC), 2021. http://hdl.handle.net/10757/655017.

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Se desarrolla un método de diseño utilizando el concepto de transmisibilidad relativa para la solución del problema de grandes desplazamientos de la base (displacement demand) en estructuras aisladas bajo acción de terremotos. El procedimiento se desarrolla en el dominio de la frecuencia, esto para obtener la rigidez y amortiguamiento del sistema aislante. Posteriormente, se utiliza un modelo de estructura benchmark de múltiples grados de libertad, excitado por señales de entrada sísmica reales para la evaluación del procedimiento de diseño, siendo la propuesta un control puramente pasivo. Los resultados muestran la eficacia de esta metodología, ya que los desplazamientos de la base obtenidos con un sistema netamente de control pasivo son muy cercanos a los desplazamientos alcanzados con el uso de sistemas control activo que son más complejos y costosos.
A design method is developed using the relative transmissibility concept to solve the problem of large base displacement (displacement demand) in isolated structures under the action of earthquakes. The procedure is developed in the frequency domain, this to obtain the stiffness and damping of the isolation system. Subsequently, a multiple degree of freedom benchmark structure model is used, excited by a real seismic input signals for the evaluation of the design procedure, the proposal is a purely passive control. The results show the effectiveness of this methodology, due to the fact that base displacement obtained with a purely passive control system are very close to displacement achieved with the use of active control systems that are more complex and expensive.
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Doré, Cyntia. "Étude de la transmissibilité d'attaches de simulateurs de vol." Mémoire, Université de Sherbrooke, 2008. http://savoirs.usherbrooke.ca/handle/11143/1424.

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Les simulateurs de vols sont très utilisés dans la formation des pilotes de lignes. Ces simulateurs reproduisent les différentes conditions de vol qu'un pilote pourrait avoir à faire face dans une situation réelle. Il est donc important qu'ils soient très représentatifs de la réalité. Le mouvement est simulé par l'action de vérins entraînant la cabine et créant l'illusion d'être dans un vrai appareil. Cependant, les vérins utilisés peuvent produire beaucoup des vibrations et l'utilisation d'isolateurs reliant les vérins à la cabine peut devenir nécessaire. Le but de cette étude était d'établir un modèle dynamique permettant l'amélioration et l'optimisation des performances d'isolateurs sur un simulateur de vol afin de minimiser le bruit à l'intérieur de l'habitacle. Pour ce faire, un modèle analytique du système vérins-isolateur-cabine a été établi. Ce dernier permet de calculer la position d'équilibre du système ainsi que de déterminer la transmissibilité en force sur la cabine. Le logiciel ANSYS a permis de valider ce modèle. Afin d'optimiser les isolateurs, il est important de s'assurer que les fréquences de résonance du système ne soient pas dans une gamme de fréquence non désirée. Pour ce faire, l'impact de la variation de différentes propriétés du système sur la position des fréquences de résonance a été étudié. Par exemple, en diminuant la masse de l'isolateur de 50%, une augmentation allant jusqu'à 25% de la position des fréquences de résonances est observée. De plus, un déplacement vers la droite du centre de gravité de l'isolateur de 50% amène les pics de résonances à se déplacer d'environ 45% vers la droite tandis qu'un changement de raideur des composantes élastiques les déplacent de 5% à 60%.

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Araújo, Iván Darío Gómez. "Análise modal operacional: métodos de identificação baseados em transmissibilidade." Universidade de São Paulo, 2015. http://www.teses.usp.br/teses/disponiveis/18/18134/tde-08042015-090459/.

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O presente trabalho tem como objetivo desenvolver novas alternativas de identificação modal para estruturas sob excitações em condição de operação baseadas em funções de transmissibilidade. Recentes metodologias formuladas sobre conceitos de transmissibilidade têm surgido como alternativa para a identificação de parâmetros modais de estruturas. A identificação nestas metodologias é independente do espectro da excitação, sendo uma vantagem importante com respeito a metodologias anteriores no domínio da frequência que supõem a excitação como ruído branco. Dessa forma, aproveitando os diferentes trabalhos dirigidos a avaliar parâmetros modais com uso da transmissibilidade, são propostas três novas alternativas. A primeira delas propõe a decomposição de valores singulares sobre matrizes de funções de transmissibilidade escalar com densidade espectral para estimar frequências naturais e modos de vibração. A segunda alternativa propõe o conceito de funções de transmissibilidade multivariável com diferente referência para a identificação modal. E a terceira introduz uma melhora na primeira alternativa incluindo a possibilidade da estimação de taxas de amortecimento. Uma ferramenta computacional para a análise modal é desenvolvida como apoio para as simulações numéricas de verificação das metodologias de identificação modal propostas. Diferentes exemplos numéricos com uma viga submetida a excitações de ruído colorido mostram que os métodos propostos são capazes de identificar parâmetros modais sem a introdução das frequências adicionais devido às excitações de ruído colorida utilizadas. Além disso, os dados de um teste de vibrações sobre uma ponte em operação foram utilizados para verificar os métodos.
This research aims to develop new alternatives of modal identification for structures under excitation in operation condition based on transmissibility functions. Latest methodologies based on transmissibility concepts have been arising as alternatives for modal parameter identification of structures. Modal parameter identification in this type methodology is input spectrum independent being an important advantage with respect previous frequency domain methods that assumes white noise excitation. Different alternatives of modal identification based on transmissibility functions are proposed in this work. The first of them proposes singular value decomposition on scalar transmissibility functions matrices with spectral density to estimate natural frequencies and vibration modes (PSDTM-SVD method). A second alternative proposes the concept of multivariable transmissibility functions with different transferring outputs for modal parameter identification. And the third alternative proposes an enhanced PSDTM-SVD method, which permits to identify modal damping. Computational tool for modal analysis is developed as a support for the numerical simulations of verification of modal identification methodologies proposed. Different numerical examples of a beam model subjected to colored noise excitations show that the proposed methods are capable of identifying modal parameters without the introduction of the additional frequencies due to the excitations used. Furthermore, data from an operational vibration bridge test were used to verify the methods.

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Lazaro, Bardales Carlos Fernando, and Neciosup Daniel Fernando Mendez. "Mejoramiento de la reducción del desplazamiento de la base en estructuras aisladas tomando en cuenta el periodo creciente en los últimos 20 años utilizando el concepto de transmisibilidad." Bachelor's thesis, Universidad Peruana de Ciencias Aplicadas (UPC), 2020. http://hdl.handle.net/10757/654489.

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En esta investigación se plantea una nueva metodología de diseño con el objetivo de obtener una mejora adicional basada en el concepto de transmisibilidad para la reducción del desplazamiento absoluto en la base aislada de una estructura. El incremento del periodo de diseño en los últimos años potencia el método propuesto basado en el concepto de transmisibilidad. Un edificio de 10 pisos es propuesto para esta investigación. Los resultados demuestran una reducción considerable en el desplazamiento de la base aislada cuando está sometida a sismos de gran magnitud.
In this research, a new design methodology based on the concept of transmissibility is proposed for the reduction of the absolute displacement in the isolated base of a structure. An increase in the design period in the last years favors the proposed method based on the transmissibility concept. A 10-story building is proposed for this research. The results show a considerable reduction in the displacement of the isolated base when it is subjected to earthquakes of great magnitude
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Dissertations / Theses on the topic 'Transmissibility'

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