Thematische Bibliographien / The displacement hypothesis

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Auswahl der wissenschaftlichen Literatur zum Thema „The displacement hypothesis“

Autor: Grafiati

Veröffentlicht am 30. Juni 2021

Zuletzt aktualisiert am 4. Februar 2022

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Zeitschriftenartikel zum Thema "The displacement hypothesis"

MUTZ, DIANA C., DONALD F. ROBERTS und D. P. van VUUREN. „Reconsidering the Displacement Hypothesis“. Communication Research 20, Nr. 1 (Februar 1993): 51–75. http://dx.doi.org/10.1177/009365093020001003.

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Ruocco, Eugenio, und Vincenzo Minutolo. „Buckling Analysis of Mindlin Plates Under the Green–Lagrange Strain Hypothesis“. International Journal of Structural Stability and Dynamics 15, Nr. 06 (17.06.2015): 1450079. http://dx.doi.org/10.1142/s0219455414500795.

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In the present paper, the influence of Green–Lagrange nonlinear strain-displacement terms, usually considered negligible under the von Kármán hypothesis, on the buckling of isotropic, moderately thick plates and shells, is investigated. The first order shear deformation plate theory is applied and the governing equations, containing nonlinear terms related to both in-plane displacement and out-of-plane rotations usually ignored in the literature, are derived using the principle of minimum of the strain energy. The general Levy type solution method is employed, and exact buckling loads and mode shapes are derived. To verify the accuracy of the solution obtained, comparisons with existing data are first made. Then, through graphics and tables, the effect of the nonlinear strain-displacement terms for a range of boundary and load conditions, variations of aspect ratio, thickness ratio and changes in geometry is presented. The results obtained show that the von Kármán's model can sensibly overestimate the critical load for structures characterized by the modes involving comparable in-plane and out-of-plane displacements.

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Huang, Hui Rong, Ji Ping Hao, Hai Xia Zhang und Yi Huang. „Displacement Fundamental Equations and Analysis of Governing Equations of the Circular Moderately Thick Shallow Spherical Shells“. Advanced Materials Research 291-294 (Juli 2011): 2071–75. http://dx.doi.org/10.4028/www.scientific.net/amr.291-294.2071.

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Displacement fundamental equations of moderately thick shallow spherical shells in polar coordinates concerning five independent variables, i.e. five middle surface displacements are established, based on the displacement fundamental equations of the moderately thick shells by transverse shearing deformation and basic hypothesis on shallow shells. Four assistant displacement functions are introduced to solve displacement fundamental equations of circular moderately thick shallow spherical shells , which are tenth-order differential equations with variable coefficient, then the decoupled governing differential equations are built up, and five displacement components through four assistant displacement functions are obtained.

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Freedman, Edward G., und David L. Sparks. „Activity of Cells in the Deeper Layers of the Superior Colliculus of the Rhesus Monkey: Evidence for a Gaze Displacement Command“. Journal of Neurophysiology 78, Nr. 3 (01.09.1997): 1669–90. http://dx.doi.org/10.1152/jn.1997.78.3.1669.

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Freedman, Edward G. and David L. Sparks. Activity of cells in the deeper layers of the superior colliculus of the rhesus monkey: evidence for a gaze displacement command. J. Neurophysiol. 78: 1669–1690, 1997. When the head is free to move, microstimulation of the primate superior colliculus (SC) evokes coordinated movements of the eyes and head. The similarity between these stimulation-induced movements and visually guided movements indicates that the SC of the primate is involved in redirecting the line of sight (gaze). To determine how movement commands are represented by individual collicular neurons, we recorded the activity of single cells in the deeper layers of the superior colliculus of the rhesus monkey during coordinated eye-head gaze shifts. Two alternative hypotheses were tested. The “separate channel” hypothesis states that two displacement commands are generated by the SC: one signal specifying the amplitude and direction of eye movements and a second signal specifying the amplitude and direction of head movements. Alternatively, a single gaze displacement command could be generated by the SC (“gaze displacement” hypothesis). The activity of collicular neurons was examined during three behavioral dissociations of gaze, eye, and head movement amplitude and direction (metrics). Subsets of trials were selected in which the amplitude and direction of either gaze shifts or eye movements or head movements were relatively constant but the metrics of the other two varied over wide ranges. Under these conditions, the separate channel and gaze displacement hypotheses make differential predictions about the patterns of SC activity. We tested these differential predictions by comparing observed patterns with predicted patterns of neuronal activity. We obtained data consistent with the predictions of the gaze displacement hypothesis. The predictions of the separate channel hypothesis were not confirmed. Thus microstimulation data, single-unit recording data, and behavioral data are all consistent with the gaze displacement hypothesis of collicular function—the hypothesis that a gaze displacement signal is derived from the locus of activity within the motor map of the SC and subsequently is decomposed into separate eye and head displacement signals downstream from the colliculus.

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Ouattara, Bazoumana. „A re-examination of the savings displacement hypothesis“. Empirical Economics 36, Nr. 3 (16.07.2008): 671–83. http://dx.doi.org/10.1007/s00181-008-0218-x.

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Roberts, Donald F., Lisa Henriksen, David H. Voelker und D. P. van Vuuren. „Television and Schooling: Displacement and Distraction Hypotheses“. Australian Journal of Education 37, Nr. 2 (August 1993): 198–211. http://dx.doi.org/10.1177/000494419303700207.

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Television is often accused of undermining children's academic achievement. This paper investigates two explanations which frequently accompany such a claim. The displacement hypothesis predicts that the time children spend with television is taken from activities that are more beneficial to school performance. The distraction hypothesis suggests that children's cumulative exposure to the structure of television—its pace, format, etc.–engenders an intolerance for the pace of schooling. A review of research on television viewing, time displacement, and academic performance fails to find any support for the displacement hypothesis. A review of studies relevant to the distraction hypothesis, however, uncovers mixed findings. This paper presents analyses of data gathered from school children in South Africa.

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Huang, Hui Rong, Ji Ping Hao, Hai Xia Zhang und Yi Huang. „Displacement Governing Equations of Moderately Thick Cylindrical Shallow Shells by Transverse Shearing Deformation and the General Solution“. Advanced Materials Research 291-294 (Juli 2011): 2066–70. http://dx.doi.org/10.4028/www.scientific.net/amr.291-294.2066.

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Displacement fundamental equations of the moderately thick cylindrical shallow shells concerning five independent variables, i.e. five middle surface displacements are established based on the displacement fundamental equations of the moderately thick shells by transverse shearing deformation and basic hypothesis on shallow shells. Three assistant displacement functions are introduced to solve the equations, which are tenth-order differential equations with variable coefficient; and then five second-order differential equations are converted into a second-order differential equation and two fourth-order transition differential equations using the Cauchy-Riemann condition, afterwards another assistant displacement function is introduced to build its decoupled governing differential equations, finally five displacement components through four assistant displacement functions are obtained.

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Liu, Dahsin, und Xiaoyu Li. „An Overall View of Laminate Theories Based on Displacement Hypothesis“. Journal of Composite Materials 30, Nr. 14 (September 1996): 1539–61. http://dx.doi.org/10.1177/002199839603001402.

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Moy, Patricia, Dietram A. Scheufele und R. Lance Holbert. „Television Use and Social Capital: Testing Putnam's Time Displacement Hypothesis“. Mass Communication and Society 2, Nr. 1-2 (Januar 1999): 27–45. http://dx.doi.org/10.1080/15205436.1999.9677860.

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Moy, Patricia, Dietram A. Scheufele und R. Lance Holbert. „Television Use and Social Capital: Testing Putnam's Time Displacement Hypothesis“. Mass Communication Society 2, Nr. 1&2 (Januar 1999): 27–45. http://dx.doi.org/10.1207/s15327825mcs0201&2_2.

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Dissertationen zum Thema "The displacement hypothesis"

Chatterjee, Souvick. „Why do mosquitoes use two modes of drinking? An analytical test of a blockage clearing hypothesis“. Thesis, Virginia Tech, 2015. http://hdl.handle.net/10919/78118.

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Mosquitoes drink using a pair of in-line muscular pumps in the head that draw liquid food through a long drinking channel termed as proboscis. Experimental investigations of mosquito drinking using synchrotron x-ray indicate two modes of drinking, a predominantly occurring continuous mode in which the anterior cibarial and posterior pharyngeal pumps expand cyclically at a constant phase difference and an isolated burst mode in which the pharyngeal pump expansion is several orders of magnitude larger than in the continuous mode. The objective of this thesis is to explain the mechanics and functional implication of this two-pump dual mode drinking of a mosquito. A reduced order mathematical model suggests that the primary role of the pharyngeal pump is in the burst mode. Since the precise geometry of the pump during drinking is yet not known, the drinking mechanism is modeled using different pump geometries based on morphological constraints in the animal. The model shows the continuous mode as being more effective in terms of energy expenditure, while the burst mode creates a large pressure difference across the proboscis which might be used to clear an obstruction in the channel or prime the channel. The hypothesis regarding the ability of a mosquito to self-clear an obstruction is analyzed by modeling the presence of an air bubble inside the system. The model indicates that air bubbles maybe able to stop flow during continuous mode drinking, and these same bubbles can be cleared by switching temporarily to burst mode drinking.
Master of Science

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Lundin-Emanuelsson, Madeleine. „Screen time and Mental health problems : A population-based study [SALVe] about screen time contribution to mental health problems among adolescents in Västmanland“. Thesis, Mälardalens högskola, Hälsa och välfärd, 2021. http://urn.kb.se/resolve?urn=urn:nbn:se:mdh:diva-55158.

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There is an increasing trend of mental health problems both globally and in Sweden. Moreover, in recent decades there has been an increase in screen time among adolescents. The present study aimed to examine the associations between screen time (i.e., smartphone, computer, and TV) and mental health problems among adolescents in Västmanland and to investigate if the association was different due to gender. A quantitative method with a cross-sectional design was applied. The study used secondary data from the Survey of Adolescent Life in Västmanland 2020. The sample consisted of 3880 adolescents from 9th grade in compulsory school and 2nd grade in upper secondary school. The results showed that high screen time on smartphone was associated with an increased probability for mental health problems in the total sample. In contrast, screen time on TV and computer showed no significant association with mental health problems. Thus, smartphone use was a significant contributor to mental health problems. Furthermore, for girls, high screen time on the smartphone, computer, and TV was associated with increased probability of mental health problems, whereas no significant associations were found among boys. In brief, this study’s findings suggest developing Swedish guidelines to regulate harmful effects from screen time.

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Valverde-Barrantes, Oscar Jesus. „A phylogenetic perspective on fine root ecology: assessing the role of root evolution on fine root functional traits and ecological interactions in woody angiosperms“. Kent State University / OhioLINK, 2013. http://rave.ohiolink.edu/etdc/view?acc_num=kent1384641579.

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Myer, Andrew James. „Hurricane Katrina, Citizen Displacement, and Social Control: A Test of the Threat and Benign Neglect Hypotheses and an Investigation of the Crime-Arrest Relationship“. University of Cincinnati / OhioLINK, 2010. http://rave.ohiolink.edu/etdc/view?acc_num=ucin1282318518.

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Bücher zum Thema "The displacement hypothesis"

Baloh, Robert W. Breuer’s Experiments on the Semicircular Canals and Otolith Organs. Oxford University Press, 2016. http://dx.doi.org/10.1093/med/9780190600129.003.0006.

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After his groundbreaking work in the mid-1860s, Josef Breuer continued to perform experiments on the inner ear balance receptors in animals. He studied the macules of fish, reptiles, and birds and noted that all these creatures had three macules arranged in the planes of the semicircular canals, perpendicular to one another. By contrast, mammals had only two macules located in the utricle (horizontal plane) and saccule (vertical plane), again perpendicular to each other. He developed the concept of “slip” to describe the movement of the otoconial membrane over the underlying sensory epithelium that occurred with linear displacement or gravity. He developed a mathematical model to hypothesize that in humans there was only one combination of responses from the two macules on each side for a single head position in space.

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Buchteile zum Thema "The displacement hypothesis"

Torske, Tore. „Terrane Displacement and Sveconorvegian Rotation of the Baltic Shield: A Working Hypothesis“. In The Deep Proterozoic Crust in the North Atlantic Provinces, 333–43. Dordrecht: Springer Netherlands, 1985. http://dx.doi.org/10.1007/978-94-009-5450-2_20.

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Montioni, Laura, Andrea Del Corona, Isabella Palano, Francesca Pichi und Matteo Scamporrino. „Evaluation and Monitoring of the Livorno’s Fossi System“. In Proceedings e report, 105–16. Florence: Firenze University Press, 2020. http://dx.doi.org/10.36253/978-88-5518-147-1.12.

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The ditches and canals of Livorno, also called Fossi, are the most characterized elements the city, not only from a historical point of view, but also and above all from an urban landscape characterization point of view. Due to the overlapping of skills not yet resolved, fragmented information and data exist regarding the real extent of the pleasure craft, the status of the canals, the provision of services and general safety. The hypothesis is to succeed, through a multi-criteria assessment of scenarios, to support and quantify the displacement of vessels that negatively affect accessibility and the landscape of Livorno's Fossi system elsewhere.

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„The Displacement Hypothesis“. In Revitalizing Political Psychology, 34–50. Psychology Press, 2004. http://dx.doi.org/10.4324/9781410611765-9.

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Marzolf, John E., und Thomas H. Anderson. „Lower Mesozoic facies and crosscutting sequence boundaries: Constraints on displacement of the Caborca terrane“. In The Mojave-Sonora Megashear Hypothesis: Development, Assessment, and Alternatives. Geological Society of America, 2005. http://dx.doi.org/10.1130/0-8137-2393-0.283.

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Huang, Chiungjung. „Internet Use and Psychological Well-Being“. In Encyclopedia of Cyber Behavior, 302–14. IGI Global, 2012. http://dx.doi.org/10.4018/978-1-4666-0315-8.ch026.

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The direction of the correlation between Internet use and psychological well-being is debatable. The displacement hypothesis indicates the correlation is negative, as Internet use for communication replaces face-to face-interaction. Conversely, the augmentation hypothesis suggests that the correlation is positive because Internet use for communication complements existing social interaction. While previous empirical findings about the relationship between Internet use and psychological well-being have been diverse, two previous meta-analyses and the present meta-analysis about the use of social networking sites and psychological well-being supported neither position, and found no relationship between Internet use and psychological well-being. Investigation of causal predominance between Internet use and psychological well-being, increased attention to measurement problems of social networking site use and older adults, and consideration of effects of indicators and moderators should be addressed in future research.

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Pescarini, Diego. „Clitics in embryo“. In Romance Object Clitics, 151–64. Oxford University Press, 2021. http://dx.doi.org/10.1093/oso/9780198864387.003.0007.

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The chapter aims to provide a principled account of the emergence of clitic pronouns in the transition from Latin to early Romance. The discussion revolves around the hypothesis that a double series of pronouns (which in Late Latin were still homophonous) emerged from the reanalysis of a discourse-driven displacement. So-called weak pronouns in Latin are strong pronouns that are displaced to the Wackernagel Position, which is analysed as a Criterial Position in the sense of Rizzi (2006, 2007). Productive interpolation in medieval Portuguese and Spanish results from the same syntactic displacement, but the Romance languages, unlike Latin, have exhibited a double series of pronouns (clitic/strong) from the earliest attestations. The emergence of a second series of pronouns witnesses a change in the morphophonological status of pronouns, which is the prelude to another change which will yield the incorporation of clitics into verbal hosts.

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Monserrati, Michele. „Little Italy, Big Japan: Patterns of Continuity and Displacement among Italian Writers in Japan“. In Searching for Japan, 137–92. Liverpool University Press, 2020. http://dx.doi.org/10.3828/liverpool/9781789621075.003.0004.

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Chapter 3 fast forwards to the post-war years and the period of reconstruction, which featured rapid economic growth in both Italy and Japan. The chapter considers the writings of Fosco Maraini, Goffredo Parise, Alberto Moravia and Italo Calvino through the ideological framework of continuity and change that was widely debated in Japan at the time of its rapid modernization. The chapter main argument is that the perceived Japanese model of societal evolution, based on a relation of continuity with the country’s past and tradition, played a central role in the writing of Italians traveling to Japan in this period by virtue of generating a contrast with the Italian model of evolution, which was predicated upon rupture and displacement. The conclusion of the chapter advances the hypothesis of a neo-exotic wave of interest toward Japan, predicated upon post-Marxist intellectuals’ quest for areas of the world that (unlike Europe) had not yet fallen under the ideological and cultural dominion of the Cold War’s bipolar order.

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Walks, Alan, und Dylan Simone. „Neoliberalization through Housing Finance, the Displacement of Risk, and Canadian Housing Policy: Challenging Minsky’s Financial Instability Hypothesis“. In Research in Political Economy, 49–77. Emerald Group Publishing Limited, 2016. http://dx.doi.org/10.1108/s0161-723020160000031004.

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Bossen, Laurel, und Hill Gates. „Bound Feet Across China“. In Bound Feet, Young Hands. Stanford University Press, 2017. http://dx.doi.org/10.11126/stanford/9780804799553.003.0006.

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The final chapter tests the general hypothesis that continued handwork by girls and women was instrumental in the persistence of footbinding. Aggregating quantitative data from our individual village sites across China and using logistic regressions, we show that when girls performed handwork for income, the likelihood that they were footbound was significantly greater than when they did not do handwork for income. Footbinding declined earlier when girls were not involved in commercial handwork. These findings are placed in the context of China’s industrialization, the spread of textile mills, and widespread displacement of girls’ hand labor in cotton textiles. The study provides solid evidence for a radically different interpretation of China’s tradition of footbinding and its deleterious, life-long effects on millions of girls and women. A major force in its eradication was the expansion of commerce and industry.

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Hunter, Douglas. „Multiple Migrations“. In Place of Stone. University of North Carolina Press, 2017. http://dx.doi.org/10.5149/northcarolina/9781469634401.003.0004.

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Esotericism enters the Dighton Rock debate through the French mythographer Antoine Court de Gébelin and Monde Primitif (1781), who believes it to be Phoenician. Ezra Stiles also favours the Phoenician interpretation and incorporates it into his Gothicist-tinged Election Sermon (1783) which presents the United States as a place of White destiny. American westward expansion produces encounters with the mysterious earthworks of the Ohio and Mississippi valleys and fuels the rise of American archaeology. Thomas Pennant in Arctic Zoology (1784) makes an influential case for the Bering Strait hypothesis of the Indigenous arrival in the Americas. Corneille de Pauw publishes Recherches philosophiques (1768-69) arguing the degenerative effect on all life of the climate of the Americas.The Anglo-Irish antiquarian Charles Vallancey argues Dighton Rock was the work of ancient migrants from Asia who were moved aside by the inferior Tartar ancestors of Native Americans. Vallancey’s theory finds near-simultaneous acceptance in a circle of theorists around Stiles as an explanation for the so-called Mound Builders. The author defines this interpretation of American prehistory as the multiple migration displacement scenario.

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Konferenzberichte zum Thema "The displacement hypothesis"

Cui, Leqing, Chinedum Okwudire und Shorya Awtar. „Complex Non-Minimum Phase Zeros in the Dynamics of Double Parallelogram Flexure Module Based Flexure Mechanisms“. In ASME 2016 Dynamic Systems and Control Conference. American Society of Mechanical Engineers, 2016. http://dx.doi.org/10.1115/dscc2016-9658.

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This paper presents a model to explain complex non-minimum phase (CNMP) zeros seen in the non-collocated frequency response of a large displacement XY flexure mechanism, which employs multiple double parallelogram flexure modules (DPFM) as building-blocks. Geometric non-linearities associated with large displacement along with the kinematic under-constraint in the DPFM, lead to a coupling between the X and Y direction displacements. Via a lumped-parameter model that captures the most relevant geometric non-linearity, it is shown that specific combinations of the operating point (i.e. flexure displacement) and mass asymmetry (due to manufacturing tolerances) give rise to CNMP zeros. This model demonstrates the merit of an intentionally asymmetric design over an intuitively symmetric design in avoiding CNMP zeros. Furthermore, a study of how the eigenvalues and eigenvectors of the flexure mechanism vary with the operating point and mass asymmetry indicates the presence of curve veering when the system transitions from minimum phase to CNMP. Based on this, the hypothesis of an inherent correlation between CNMP zeros and curve veering is proposed.

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Buryachenko, Valeriy A. „Generalized Method of Effective Field in Linear Peridynamic Micromechanics of Random Structure Composites“. In ASME 2020 International Mechanical Engineering Congress and Exposition. American Society of Mechanical Engineers, 2020. http://dx.doi.org/10.1115/imece2020-24574.

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Abstract A statistically homogeneous random matrix medium with the bond-based peridynamic properties of constituents is considered. For the media subjected to remote homogeneous volumetric boundary loading, one proved that the effective behavior of this media is governing by conventional effective constitutive equation which is the same as for the local elasticity theory. The average is performed over the surface of the extended inclusion phase rather than over an entire space. Any spatial derivatives of displacement fields are not required. The basic hypotheses of locally elastic micromechanics are generalized to their peri-static counterparts. In particular, in the generalized method of effective field proposed, the effective field is evaluated from self-consistent estimations by the use of closing of a corresponding integral equation in the framework of the quasi-crystalline approximation. In so doing, the classical effective field hypothesis is relaxed, and the hypothesis of the ellipsoidal symmetry of the random structure of CMs is not used. One demonstrates some similarity and difference with respect to other methods (the dilute approximation and Mori-Tanaka approach) proposed before in peridynamic micromechanics of CMs. Comparative numerical analyses of these methods are performed for 1D case.

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Luo, Chuan, Kai-Yi Hsiao, Perry Cheung, Howard Lin, A. Q. Shen, G. Z. Cao und I. Y. Shen. „Effects of Air on Enclosure Design of Lead-Zirconate-Titanate (PZT) Thin-Film Diaphragm Microactuators“. In ASME 2012 International Design Engineering Technical Conferences and Computers and Information in Engineering Conference. American Society of Mechanical Engineers, 2012. http://dx.doi.org/10.1115/detc2012-70061.

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In this paper, we evaluate performance of two types of piezoelectric diaphragm micro-actuators: open-end design and closed-end design. In the open-end design, the micro-actuator consists of a base silicon diaphragm, a layer of bottom electrode, a layer of lead-zirconate-titanate (PZT) thin film, and a layer of top electrode. The diaphragm is anchored on a silicon substrate by etching the silicon substrate from the back to form a cavity under the diaphragm. In the closed-end design, the bottom of the cavity is sealed with a piece of glass, silicon or PDMS. Experimental results show that the measured displacements from the closed-end design are always 5%–30% lower than those from the open-end design. To explain the experimental results, we hypothesize that the air inside the cavity of the closed-end design behaves like an elastic spring increasing the stiffness of the closed-end design. To confirm the hypothesis, we estimate the stiffness of the air by modeling the air as an ideal gas with a constant temperature. We also model the diaphragm as a lumped spring. Combination of the stiffness from the diaphragm and the air predicts the overall stiffness and displacement of the closed-end design. The predictions agree well with the experimental measurements, indicating that the air in the cavity significantly stiffens the closed-end design.

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Ballot, Eric, und Pierre Bourdet. „An Integrated Framework for 3D Tolerance Chains in Design and Manufacturing“. In ASME 2001 International Design Engineering Technical Conferences and Computers and Information in Engineering Conference. American Society of Mechanical Engineers, 2001. http://dx.doi.org/10.1115/detc2001/dac-21023.

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Abstract This paper is about a new model of geometric deviation to compute tridimensional tolerance chains. By the use of a simplification of geometric deviation well adapted to computation of tolerances, we will show how to compute systematically the consequences of geometric deviation from functional requirements to manufacturing. Under the hypothesis that geometric deviations lead only to small displacement of parts, we will demonstrate how their propagation can be computed. We will highlight the improvement yielded by the proposed model and the consequences on the description of tolerances and manufacturing.

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Alamo, Fredy Coral, und Hans Ingo Weber. „Dynamics of Beams Using a Geometrically Exact Elastic Rod Approach“. In ASME 8th Biennial Conference on Engineering Systems Design and Analysis. ASMEDC, 2006. http://dx.doi.org/10.1115/esda2006-95158.

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The dynamics of a long slender beam, intrinsically straight, is addressed systematically for 3-D problems using the Cosserat rod theory. The model developed allows for bending, extension/compression and torsion, thus enabling the study of the dynamics of various types of elastic deformations. In this work a linear constitutive relation is used, also, the Bernoulli hypothesis is considered and the shear deformations are neglected. The fundamental problem when using any finite element (FE) formulation is the choice of the displacement functions. When using Cosserat rod theory this problem is handled using approximate solutions of the nonlinear equations of motion (in quasi-static sense). These nonlinear displacement functions are functions of generic nodal displacements and rotations. Based on the Lagrangian approach formed by the kinetic and strain energy expressions, the principle of virtual work is used to derive the nonlinear ordinary differential equations of motion that are solved numerically. As an application, a curved rod, formed by many straight elements is investigated numerically. When using the Cosserat rod approach, that take into account all the geometric nonlinearities in the rod, the higher accuracy of the dynamic responses is achieved by dividing the system into a few elements which is much less than the traditional FE methods, this is the main advantage when using this approach. Overall, the Cosserat model provides an accurate way of modelling long slender beams and simulation times are greatly reduced through this approach.

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do Carmo, Thiago B., J. Riley Edwards, Ryan G. Kernes, Bassem O. Andrawes und Chris P. L. Barkan. „Laboratory and Field Investigation of the Rail Pad Assembly Mechanistic Behavior“. In 2014 Joint Rail Conference. American Society of Mechanical Engineers, 2014. http://dx.doi.org/10.1115/jrc2014-3784.

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To achieve the performance demands due to growing heavy-haul freight operations and increased high-speed rail service worldwide, advancements in concrete crosstie fastening systems are required. A mechanistic design approach based on scientific principles and derived from extensive laboratory and field investigation has the potential to improve the current best practices in fastening system design. The understanding of failure modes and effects on each component, associated with an improved understanding of load distribution and mechanical behavior, will ultimately increase production and operational efficiency while reducing unscheduled maintenance, track outages, and unplanned additional costs. Improvements on the rail pad assemblies, the components responsible for attenuating loads and protecting the concrete crosstie rail seat, will enhance the safety and efficiency of the track infrastructure. Understanding the mechanistic behavior of rail pad assemblies is critical to improving the performance and life cycle of the infrastructure and its components, which will ultimately reduce the occurrence of potential failure modes. Lateral, longitudinal, and shear forces exerted on the components of the fastening system may result in displacements and deformations of the rail pad with respect to the rail seat and rail base. The high stresses and relative movements are expected to contribute to multiple failure mechanisms and result in an increased need for costly maintenance activities. Therefore, the analysis of the mechanics of pad assemblies is important for the improvement of railroad superstructure component design and performance. In this study, the lateral displacement of this component with respect to the rail base and rail seat is analyzed. The research ultimately aims to investigate the hypothesis that relative displacement between the rail pad and rail seat occurs under realistic loading environments and that the magnitude of the displacement is directly related to the increase in wheel loads.

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Nikkhah-Bahrami, M., und Abazar Shamekhi. „Free Vibration Analysis of Circular FGM Plate Having Variable Thickness Under Axisymmetric Condition by Finite Element Method“. In ASME 2005 International Design Engineering Technical Conferences and Computers and Information in Engineering Conference. ASMEDC, 2005. http://dx.doi.org/10.1115/detc2005-84021.

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This study presents the free vibration analysis of circular plate having variable thickness made of functionally-graded material. The boundary conditions of the plate is either simply supported or clamped. Dynamic equations were obtained using energy method based on Love-Kichhoff hypothesis and Sander’s non-linear strain-displacement relation for thin plates. The finite element method is used to determine the natural frequencies. The results obtained show good agreement with known analytical data. The effects of thickness variation and Poisson’s ratio are investigated by calculating the natural frequencies. These effects are found not to be the same for simply supported and clamped plates.

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Ramzanpour, Mohammadreza, Mohammad Hosseini-Farid, Jayse McLean, Mariusz Ziejewski und Ghodrat Karami. „A Logistic Regression Analysis for Tissue Stiffness Categorization Through Magnetic Resonance Elastography“. In ASME 2020 International Mechanical Engineering Congress and Exposition. American Society of Mechanical Engineers, 2020. http://dx.doi.org/10.1115/imece2020-23929.

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Abstract Magnetic resonance elastography (MRE) is commonly used as an image-based alternative for palpation of the internal organs of human body. The presence of tumor or other kind of pathologies in biological tissues can increase its stiffness. Therefore, while MRE technique is capable to provide a quantitative measurement, the qualitative description of the tissue stiffness could be potentially informative as well for physicians. MRE can be divided into several steps including the generation of waves in the tissue, measuring the field displacement of the tissue by magnetic resonance imaging devices, and then applying the constitutive based inversion algorithms to measure the material properties of the tissue. The inversion algorithms are dependent to the constitutive model in use, and moreover, it could be computationally expensive. To overcome this hindrance, in this paper, we propose a machine learning framework for categorizing the tissue stiffness based on the magnetic resonance elastography finite element simulation data. In our finite element simulation, the shear waves are generated in an axisymmetrical model by applying harmonic displacement at the center of the model with the known excitation frequency. To obtain the field displacement of the model, in the first step, the natural frequencies of the system will be calculated through numerical Block-Lanczos eigensolver algorithm. Thereafter, a transient dynamic modal analysis is carried out to find the corresponding displacement response of the tissue in different time steps of the simulation. To obtain the training dataset, ten simulations with the pre-assigned linear elastic modulus in the range of 2 to 6 kPa is conducted and the displacement of the tissue in three points at the end of the first and second cycle will be recorded as the features of the dataset. Each instance of the dataset is labelled as “Low“ or “High”, corresponding to its stiffness quantitative value lying in ranges of 2–4 kPa or 4–6 kPa. A machine learning classifying algorithm, a logistic regression hypothesis will be trained on this dataset. The trained hypothesis will be then tested on six new unseen simulation data with known elastic modulus values. The trained logistic regression was able to classify the tissue stiffness with the perfect accuracy score of 1.0. The findings of this study can be used for qualitative description of the tissue stiffness that can be beneficial for pathology diagnosis and moreover, it eliminates the need on the usage of inversion algorithms which leads to reduction in the computational complexity of tissue characterization.

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Baglioni, Stefano, Claudio Braccesi, Filippo Cianetti, Antonio Ficola und Carmelo Anile. „Design of a Biomedical Device Through Non Linear Analysis“. In ASME 2015 International Mechanical Engineering Congress and Exposition. American Society of Mechanical Engineers, 2015. http://dx.doi.org/10.1115/imece2015-51765.

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The most widely accepted hypothesis to explain normal pressure hydrocephalus (NPH) points at the increase of cerebrospinal fluid (CSF) outflow resistance as the fundamental cause. Some clinical and experimental studies do not agree with this hypothesis and suggest that NPH is related to an alteration of the CSF pulse pressure waveform, while intracranial pressure (ICP) mean value has negligible effects. The current treatment of hydrocephalus is based on the first hypothesis and consists in the implantation of CSF shunts. An improved treatment can be obtained by damping the ICP pressure peaks and keeping unchanged the mean value. The target of this work is to design a special ICP regulator valve, that will be implanted in a human body and that must be characterized by a purely mechanical working principle avoiding any electrical equipment (sensors, actuators...). This device is currently patented [1] and in virtue of that the paper will focus only on the general device working principle and design methodology rather than specific data. Since the device must be implanted inside the patient head, the system must satisfy very restrictive requirements: low weight and dimensions in order to avoid possible patient discomfort or obstacles to the normal life activities, in addition, being the valve application place close to a delicate organ such the brain is, the mechanism must be very simple and must reach very high reliability standards (almost zero maintenance and possible failures). The idea is to realize a device in which the hydraulic flow is governed by a spring with variable stiffness with respect to the applied loads (intracranial pressure: characterized by both a mean constant component and by random oscillatory phenomenon). To maximize the valve effect about pressure peaks reduction, the spring will be designed with a strongly non-linear behavior characterized by bistable working principle. The systems that show this properties are innumerable, but according to the author hypothesis to realize a mechanism as simpler as possible the choice done falls into the thin curved plate (shell) category. In particular, the goal is to obtain a plate behavior called “Buckling Behavior”: under determined load conditions the plate geometric configuration must suddenly switch from an equilibrium position to another. The two target parameters which describe this phenomenon are the buckling critical load that is the applied load value for which the plate change the geometric configuration (valve activation point) and the load application point displacement (evacuation pipe opening). The adopted design method is the non-linear analysis developed in a finite element analysis (F.E.A.) environment, by which it is possible to analyze a component behavior also in case of large displacements. To identify the optimal component geometry the load application point displacement versus the acting load was evaluated as function of the main parameters describing the plate profile: plate semi-length, curvature radius and semi-length of the plate plane portion. This work represents only a preliminary study oriented to demonstrate the feasibility in realizing a biomedical valve for fluids pressure control, adopting a thin curved plate with “Buckling Behavior”. Moreover it provides useful information for the designer who wants to realize curved plate with buckling behavior showing the influence of the main geometric parameters on this phenomenon. Further in depth studies oriented to: the spring stiffness regulation for different patients, best material choice and productive process must be accomplished before the device realization.

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Shamekhi, Abazar, und Mohammad H. Naei. „Buckling Analysis of Circular FGM Plate Having Variable Thickness Under Uniform Compression by Finite Element Method“. In ASME 2005 International Design Engineering Technical Conferences and Computers and Information in Engineering Conference. ASMEDC, 2005. http://dx.doi.org/10.1115/detc2005-84019.

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This study presents the buckling analysis of radially-loaded circular plate with variable thickness made of functionally-graded material. The boundary conditions of the plate is either simply supported or clamped. The stability equations were obtained using energy method based on Love-Kichhoff hypothesis and Sander’s non-linear strain-displacement relation for thin plates. The finite element method is used to determine the critical buckling load. The results obtained show good agreement with known analytical and numerical data. The effects of thickness variation and Poisson’s ratio are investigated by calculating the buckling load. These effects are found not to be the same for simply supported and clamped plates.

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