Academic literature on the topic 'Dampier family'
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Journal articles on the topic "Dampier family"
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Szary, Marek L., and Peter Weber. "The Study of Behavior of Vibrating Systems Controllable by Devices with Rheological Fluid." Archives of Acoustics 38, no. 2 (June 1, 2013): 217–22. http://dx.doi.org/10.2478/aoa-2013-0026.
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Abstract The nonlinear mathematical model of behavior of controllable viscosity fluid (CVF) under applied external field is presented. A large family of these fluids is commonly used to control responding forces of dampers in vibration control applications. The responding force of a damper with CVF has two components. The first one - uncontrollable - is proportional to the viscosity of a base fluid and velocity of its motion, the second one, which is controllable, depends on the strength of the applied external field. Both are involved in the process of dissipation of unwanted energy from the vibrating systems. An equivalent damping factor based on the principle of energy dissipated during one cycle of damper work under a constant strength external field was calculated. When mass or stiffness is variable the equivalent damping factor can be set accordingly by adjusting the strength of external field to have vibrating damped system purposely/continuously working in the critical or other chosen state. This paper also presents cases of applying periodically changing strengths of an external field synchronized with cycles of periodical motion of the vibrating system to continuously control the damping force within each cycle.
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Sefler, J. F., and A. P. Pisano. "The Design, Experimentation, and Simulation of a Novel Coulomb Friction Device for Automotive Valve Spring Damping." Journal of Mechanical Design 115, no. 4 (December 1, 1993): 871–76. http://dx.doi.org/10.1115/1.2919281.
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This investigation contains experimental and computer modeling results of an alternative method for damping automotive valve springs, in which a nondestructive elastomeric sleeve that slides over the spring with an interference fit is used to provide coulomb damping on the outside of the valve spring coils. The damper and valve spring dynamics are modeled using the wave equation with a damping term composed of both viscous and coulomb components. Although the damper is very simple and inexpensive, the reduction in residual spring vibrations are shown to be significant without loss of valve spring performance. Experimental data taken from a 1983 Pontiac family-II, 1.8 liter, four cylinder, single overhead cam engine equipped both with and without the new elastomeric dampers is used to verify the results of the computer simulation and demonstrate the effectiveness of the damper.
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Modi, V. J., A. Akinturk, and W. Tse. "A Family of Efficient Sloshing Liquid Dampers for Suppression of Wind-Induced Instabilities." Journal of Vibration and Control 9, no. 3-4 (March 2003): 361–86. http://dx.doi.org/10.1177/107754603030773.
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Bluff structures in the form of tall buildings, smokestacks, control towers, bridges, etc., are susceptible to vortex resonance and galloping type of instabilities. One approach to vibration control of such systems is through energy dissipation using sloshing liquid dampers. In this paper we focus on enhancing the energy dissipation efficiency of a rectangular liquid damper through the introduction of two-dimensional obstacles as well as floating particles. The investigation has two phases. To begin with, a parametric free vibration study aimed at the optimization of the obstacle geometry is undertaken to arrive at configurations promising increased damping ratio and hence higher energy dissipation. The study is complemented by an extensive wind tunnel test program, which substantiates the effectiveness of this class of damper in suppressing both vortex resonance and galloping type of instabilities. Simplicity of design, ease of implementation, minimal maintenance, reliability as well as high efficiency make such liquid dampers quite attractive for real-life applications.
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Hayashi, Ken-Ichi. "Lysmata dispar sp. nov., a new shrimp from the Dampier Archipelago, Western Australia, with notes on other species of the family Hippolytidae (Crustacea: Decapoda: Caridea)." Records of the Western Australian Museum, Supplement 73, no. 1 (2007): 85. http://dx.doi.org/10.18195/issn.0313-122x.73.2007.085-095.
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Martorell, F., Vicenç Torra, Antonio Isalgué, M. L. Perea, Patrick Terriault, and Francisco C. Lovey. "Damping by SMA in Civil Engineering Structures." Advances in Science and Technology 56 (September 2008): 92–97. http://dx.doi.org/10.4028/www.scientific.net/ast.56.92.
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The particular properties of Shape Memory Alloys associated to their thermoelastic martensitic transformation with hysteresis permits applications of SMA as a damper via the conversion of the work absorbed in each cycle in heat. The guaranteed behavior requires the appropriateness of SMA for the complete requirements of the application. This work shows two complementary aspects of the SMA application in Civil Engineering, the first of them, the SMA dampers in earthquake damping of a family house. The second aspect relates an elementary approach to the damping of stayed cables in bridges, using some data from the Iroise Bridge. The application in the first case needs long time constancy of properties and then around 200 cycles during an earthquake. In the second case, the fatigue life of SMA imposes that only small strains in the alloy can be accepted. Finally, it is emphasized the importance of working conditions, including temperature and time.
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Fu, Bo, Huanjun Jiang, and Jin Chen. "Substructure Shake Table Testing of Frame Structure–Damper System Using Model-Based Integration Algorithms and Finite Element Method: Numerical Study." Symmetry 13, no. 9 (September 18, 2021): 1739. http://dx.doi.org/10.3390/sym13091739.
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Substructure shake table testing (SSTT) is an advanced experimental technique that is suitable for investigating the vibration control of secondary structure-type dampers such as tuned mass dampers (TMDs). The primary structure and damper are considered as analytical and experimental substructures, respectively. The analytical substructures of existing SSTTs have mostly been simplified as SDOF structures or shear-type structures, which is not realistic. A common trend is to simulate the analytical substructure via the finite element (FE) method. In this study, the control effects of four dampers, i.e., TMD, tuned liquid damper (TLD), particle damper (PD) and particle-tuned mass damper (PTMD), on a frame were examined by conducting virtual SSTTs. The frame was modeled through stiffness-based beam-column elements with fiber sections and was solved by a family of model-based integration algorithms. The influences of the auxiliary mass ratio, integration parameters, time step, and time delay on SSTT were investigated. The results indicate that the TLD had the best performance. In addition, SSTT using model-based integration algorithms can provide satisfactory results, even when the time step is relatively large. The effects of integration parameters and time delay are not significant.
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Gérard, Patrick, Sandrine Grellier, and Zihui He. "Turbulent cascades for a family of damped Szegő equations." Nonlinearity 35, no. 9 (August 16, 2022): 4820–49. http://dx.doi.org/10.1088/1361-6544/ac7e13.
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Abstract In this paper, we study the transfer of energy from low to high frequencies for a family of damped Szegő equations. The cubic Szegő equation has been introduced as a toy model for a totally non-dispersive degenerate Hamiltonian equation. It is a completely integrable system which develops growth of high Sobolev norms, detecting transfer of energy and hence cascades phenomena. Here, we consider a two-parameter family of variants of the cubic Szegő equation and prove that, adding a damping term unexpectedly promotes the existence of turbulent cascades. Furthermore, we give a panorama of the dynamics for such equations on a six-dimensional submanifold.
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Dampier, Carlton, Elizabeth Ely, Leela Aertker, Darcy Brodecki, Karen Kesler, and Marie Stuart. "Pain In Infants and Young Children with Sickle Cell Disease-a Prospective Longitudinal Analysis." Blood 116, no. 21 (November 19, 2010): 841. http://dx.doi.org/10.1182/blood.v116.21.841.841.
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Abstract Abstract 841 Pain is the hallmark symptom of vaso-occlusion in sickle cell disease (SCD), but has not been well studied, particularly in children. Previous studies of pain in very young children with SCD have largely been limited to episodes sufficiently severe as to require acute care visits or hospitalizations. Our previous studies in school-aged children and adolescents (Dampier CD et al. J Pediatr Hematol Oncol 2004), as well as those in adults (Smith W et al Ann Inter Med 2009) suggest that vaso-occlusive pain is frequently managed at home outside of acute care medical settings. We sought to obtain similar data about the home pain experience of infants and young children with SCD as reported by parents or guardians, and to explore the relationship between the pain experience and hematological biomarkers. Enrollment and data collection was conducted from Jan 1999-Mar 2008 at the Marian Anderson Sickle Cell Center as part of the Comprehensive Sickle Cell Centers program. Families with SCD infants identified by newborn screening were first approached about the study after completion of confirmatory diagnosis and initial SCD-related education, usually between 4 to 6 months of age. After informed consent, parents/guardians were trained in pain assessment and daily reporting. When sickle cell related pain events occurred, parents/guardians reported pain occurrence, location, associated symptoms and the treatment that they provided. Daily paper diaries were generally used in the first year of life to familiarize families with pain assessment and reporting. Subsequently a novel daily pager system was used to provide a method allowed daily reporting, but with reduced participant burden. A monthly telephone system in conjunction with a daily calendar was used for those families unable to effectively comply with providing daily reports. All pain reports were adjudicated by consensus of study staff and PI/Co-PI. Children were removed from the study for any period of chronic transfusion for clinical events (splenic sequestration, recurrent acute chest syndrome, surgery). Over the study period, 103 children (58% male) were enrolled beginning at a median age of 7.3 months (range 1.5, 65.2 months). This represented about 50% of SCD children referred to the Center by newborn screening during these time periods; the most common reasons for refusal were inability to complete daily reporting and geographic distance from the Center. An SS genotype was present in 50 children (48.5%), SC in 32 (31.1%), SB0thalassemia in 6 (5.8%), SB+thalassemia in 15 (14.6%). Children were actively followed for a median of 3.8 years (range 0.3–7.6 years). The total number of days children were assessed for pain was 141,197 days with an additional 28,079 days of missing data (16%). The total number of days that children had reported pain was 2,288 days (1.6%), which represented 768 distinct episodes of pain. Over 80% of children reported to have pain in the 0–12 month age interval had pain locations (hands/feet) and characteristics (swelling or tenderness) consistent with dactylitis, which became progressively less prevalent in older age intervals. Significantly more SS/SB0 patients (58%) had >2 days of average dactylitis pain during 0–12 months or 12–24 months (53%) intervals compared to SC/SB+ patients (0%) (p=0.04). The timing of the first reported dactylitis event (<2 years or ≥2 years) significantly predicted the frequency of SCD pain events per person year, with earlier onset associated with more frequent pain events during the study period (p=0.02), for both the SS/SB0 and SC/SB+ (P=0.03) groups. Our study demonstrates the feasibility of initial recruitment and subsequent daily reporting of clinical events by families of infants and young children with SCD over many years, particularly when careful consideration is given to enhance family support and minimizing respondent burden. The onset of an initial dactylitis episode prior 2 years of age, even if treated at home, was associated with more frequent pain throughout childhood, irrespective of hemoglobinopathy type. Such children may be appropriate for interventions, such as oral hydroxyurea, that reduce excessive pain frequency. Supported by NIHHL-051495 and HL-083705. Disclosures: Dampier: Anthera Pharmaceuticals Inc:; Glycomimetics Inc: .
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Skalski, Paweł, and Klaudia Kalita. "Role of Magnetorheological Fluids and Elastomers in Today’s World." Acta Mechanica et Automatica 11, no. 4 (December 1, 2017): 267–74. http://dx.doi.org/10.1515/ama-2017-0041.
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AbstractThis paper explains the role of magnetorheological fluids and elastomers in today’s world. A review of applications of magnetorheological fluids and elastomers in devices and machines is presented. Magnetorheological fluids and elastomers belong to the smart materials family. Properties of magnetorheological fluids and elastomers can be controlled by a magnetic field. Compared with magnetorheological fluids, magnetorheological elastomers overcome the problems accompanying applications of MR fluids, such as sedimentation, sealing issues and environmental contamination. Magnetorheological fluids and elastomers, due to their ability of dampening vibrations in the presence of a controlled magnetic field, have great potential present and future applications in transport. Magnetorheological fluids are used e.g. dampers, shock absorbers, clutches and brakes. Magnetorheological dampers and magnetorheological shock absorbers are applied e.g. in damping control, in the operation of buildings and bridges, as well as in damping of high-tension wires. In the automotive industry, new solutions involving magnetorheological elastomer are increasingly patented e.g. adaptive system of energy absorption, system of magnetically dissociable [hooks/detents/grips], an vibration reduction system of the car’s drive shaft. The application of magnetorheological elastomer in the aviation structure is presented as well.
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Bollimpalli, D. A., M. Wielgus, D. Abarca, and W. Kluźniak. "Atmospheric oscillations provide simultaneous measurement of neutron star mass and radius." Monthly Notices of the Royal Astronomical Society 487, no. 4 (June 10, 2019): 5129–42. http://dx.doi.org/10.1093/mnras/stz1597.
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ABSTRACT Neutron stars with near-Eddington observable luminosities were shown to harbour levitating atmospheres, suspended above their surfaces. We report a new method to simultaneously measure the mass and radius of a neutron star based on oscillations of such atmospheres. In this paper, we present an analytic derivation of a family of relativistic, oscillatory, spherically symmetric eigenmodes of the optically and geometrically thin levitating atmospheres, including the damping effects induced by the radiation drag. We discover characteristic maxima in the frequencies of the damped oscillations and show that from a measurement of the frequency maximum and of the luminosity one can determine the mass and radius of the neutron star. In addition to the stellar parameters, observation of the variation of the oscillation frequencies with flux would allow us to estimate the stellar luminosity and therefore the distance to the source with an accuracy of a few per cent. We also show that the ratio of any two undamped eigenfrequencies depends only on the adiabatic index of the atmosphere, while for the damped eigenfrequencies, this ratio varies with the luminosity. The damping coefficient is independent of the mode number of the oscillations. Signatures of the dynamics of such atmospheres will be reflected in the source’s X-ray light curves.
Dissertations / Theses on the topic "Dampier family"
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Darendeli, Mehmet Baris. "Development of a new family of normalized modulus reduction and material damping curves." Access restricted to users with UT Austin EID Full text (PDF) from UMI/Dissertation Abstracts International, 2001. http://wwwlib.umi.com/cr/utexas/fullcit?p3025211.
Full textBooks on the topic "Dampier family"
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Mahood, Marie. Icing on the damper: Life story of a family in the outback. Rockhampton Q: Central Queensland University Press, 1995.
Find full textBook chapters on the topic "Dampier family"
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Jehel, Pierre, Pierre Léger, and Adnan Ibrahimbegovic. "Structural Seismic Fragility Analysis of RC Frame with a New Family of Rayleigh Damping Models." In Computational Methods in Stochastic Dynamics, 267–91. Dordrecht: Springer Netherlands, 2013. http://dx.doi.org/10.1007/978-94-007-5134-7_16.
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Bouajaji, M. El, V. Dolean, M. J. Gander, and S. Lanteri. "Comparison of a One and Two Parameter Family of Transmission Conditions for Maxwell’s Equations with Damping." In Lecture Notes in Computational Science and Engineering, 271–78. Berlin, Heidelberg: Springer Berlin Heidelberg, 2013. http://dx.doi.org/10.1007/978-3-642-35275-1_31.
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Bowern, Claire. "Gradualness and abruptness in linguistic split." In The Life Cycle of Language, 399–411. Oxford University PressOxford, 2023. http://dx.doi.org/10.1093/oso/9780192845818.003.0025.
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Abstract While the Nyulnyulan languages have long been identified as a clear family, two languages from the geographic center of the family have been difficult to classify. In this chapter, I use previously unutilized archival finds to discuss a conundrum long noted in linguistics, often characterized as the competition of gradualist diffusionist models versus abrupt splits that are typically represented on linguistic trees. The Nyulnyulan family has been claimed to form an old dialect continuum down the Dampier Peninsula, with overlapping changes that make it difficult to discern one “language” from another or to posit clear subgroups. I dispute this claim and argue that both linguistically and culturally, there are distinct language units. I use a combination of fieldwork data, historical reconstruction, and archival resources to show how changes have locally diffused, but subsequent population shifts and local realignments have created sharp junctures between varieties.
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Lam, David, and Ahmed Elsayed. "Child Labour and the Youth Employment Challenge." In Labour Markets in Low-Income Countries, 167–83. Oxford University Press, 2021. http://dx.doi.org/10.1093/oso/9780192897107.003.0007.
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Chapter 7 focuses on children and youth, a critical topic given the young age structures in many low-income countries. Widespread child employment can dampen future economic growth through its negative impact on child development and depress current growth by reducing unskilled wages and discouraging the adoption of skill-intensive technologies. Rising incomes are associated with a greater demand for children’s education and leisure and with improvements in the family’s ability to buffer economic shocks without child labour. All of these factors lead to declines in the economic activity of children when income levels are on the rise. The chapter also discusses the challenges to youth employment in LICs. While the large cohort of youth entering Africa’s labour force is better educated than previous cohorts, jobs remain elusive in the formal wage sector, given the limited success in African economies in structural transformation from low productivity agriculture to higher productivity non‐agricultural sectors.
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Goldsmith, Oliver. "A town wit described. The dullest fellows may learn to be comical for a night or two." In The Vicar of Wakefield, edited by Robert L. Mack and Arthur Friedman. Oxford University Press, 2008. http://dx.doi.org/10.1093/owc/9780199537549.003.0007.
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When the morning arrived on which we were to entertain our young landlord, it may be easily supposed what provisions were exhausted to make an appearance. It may also be conjectured that my wife and daughters expanded their gayest plumage upon this occasion. Mr. Thornhill came with a couple of friends, his chaplain and feeder.* The servants, who were numerous, he politely ordered to the next ale-house: but my wife, in the triumph of her heart, insisted on entertaining them all; for which, by the bye, our family was pinched for three weeks after. As Mr. Burchell had hinted to us the day before, that he was making some proposals of marriage to Miss Wilmot, my son George’s former mistress, this a good deal damped the heartiness of his reception: but accident, in some measure, relieved our embarrasment; for one of the company happening to mention her name, Mr. Thornhill observed with an oath, that he never knew any thing more absurd than calling such a fright a beauty: ‘For strike me ugly,’ continued he, ‘if I should not find as much pleasure in choosing my mistress by the information of a lamp under the clock at St. Dunstan’s.* At this he laughed, and so did we:—the jests of the rich are ever successful. Olivia too could not avoid whispering, loud enough to be heard, that he had an infinite fund of humour.
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Bennett, Peggy D. "Privacy for us." In Teaching with Vitality. Oxford University Press, 2017. http://dx.doi.org/10.1093/oso/9780190673987.003.0059.
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It is difficult to know the consequences of sharing private information with co- workers. Even when our school friends are eager listeners, curious conversationalists, and supportive responders, it is judicious to think about our personal privacy. Many of us have had to learn a sense of privacy. Some of us do not think much about it. Ask, “What do I want to keep private about myself in my school?” “Do I monitor the stories and experiences (my own or others’) that I share with school staff?” “Do I acknowledge that listeners make assumptions about my life that I may never know have been made?” Very few confidants will be as careful with our words and our intentions as we are. Our acceptable boundaries for risky behaviors, family habits, and health challenges may not match those of our school colleagues. Be savvy. Appropriately withholding information or diverting the focus in response to a personal question is not rude and may be judicious. A weekend trip to gamble, a potentially serious health diagnosis, the intent to seek a new job— how do we decide what to keep private? Because our co- workers are our most frequent social group, do we feel free to share all our experiences, in schools and out? Unbridled openness can be risky for professional comportment and grounded personal behaviors. Once shared, private information cannot be unshared. Where do we draw the line for our personal privacy? Being strategic about privacy in schools is both wise and practical. We set our boundaries for the personal information we do and do not share with co- workers. And that line will likely move— indeed, perhaps it needs to be adjusted— with age and experience. Keeping a secret tends to have a “shelf life,” based on the memory, mood, and ethics of the listener. Consider making a distinction between “school talk” and “home talk.” When we keep our personal lives private, we have a better chance of deciding what of our lives is and is not shared in schools. Maintaining personal privacy need not dampen or inhibit strong ties and warm relationships with colleagues. These important privacy decisions let us determine the parameters of our communications. When we live our lives with such wisely informed decisions, we feel strong, mature, and self- satisfied.
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Lucey, Michael. "The Place of the Oedipal: Gide Writing Home From North Africa." In Gide’s Bent, 42–67. Oxford University PressNew York, NY, 1995. http://dx.doi.org/10.1093/oso/9780195080865.003.0003.
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Abstract In particular, I will be observing Gide’s relation to the oedipalizing narratives so familiar to many “Freudian” accounts of the arrival at “homosexuality.” My impression is that Gide perceives many of the ways such narratives deny, or at least work to dampen, many of the political complexities, much of the political potential, of sexuality; my impression is also that the Gidean text struggles in various ways against this dampening effect, against this possible denial. This struggle is what interests me in this chapter. I will be building on some of the considerations as to the confused temporality of sexuality from the last chapter; I will also be trying to elaborate the discussion of Gide’s relation to North Africa, though from a rather different angle. The main new departure here, one that plays an important role in making the analyses of future chapters possible, is my discussion of Gide’s ambivalent relation to female figures in the construction of his sexuality: ambivalent in that he finds certain things he might feel loyal to in the marginal status of certain female sexualities even as he feels an often violent urge to define himself over against the feminine. Si le grain ne meurt can be read as a form of self analysis, a place in which Gide tries to construct in narrative form an explanation of his own sexual development, or perhaps we should say a place where he confronts the difliculties that kind of explanatory effort inevitably involves. It is in the context of such difficulties, for instance, that one feels drawn to read the following scene, described by Gide on only the second or third page of his hook. The Gides are on a visit to his father’s side of the family in Uzes, and on this particular day they are visiting “!es cousins de Flaux”: Gide passes on immediately without comment, hut the scene resonates with many others in the book in which he writes as if to come to terms with his relationship to female sexuality and to his mother in particular. l would like here to draw a group of these scenes together in order to find out what precisely Gide thinks he can explain about his homosexuality-his struggle to fix on, accept, and account for a particular 01lject choice-by writing (often very obliquely) about his mother’s sexuality and his own relationship to it.
Conference papers on the topic "Dampier family"
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Gharib, Mohamed, and Mansour Karkoub. "Passive Multi-Degree-of-Freedom Structural Control Using LPC Impact Dampers." In ASME 2015 International Mechanical Engineering Congress and Exposition. American Society of Mechanical Engineers, 2015. http://dx.doi.org/10.1115/imece2015-51376.
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Excessive vibration is one of the main reasons leading to partial damage and in some cases collapse of tall buildings and structures. Impact dampers provide an effective, economical, and easy to install solution to the vibration problem in several applications. The latest developed type in the impact dampers family is the Linear Particle Chain (LPC) impact damper. It consists of a linear arrangement of two sizes of freely moving masses, constrained by two stops. This paper presents the results of an experimental investigation on the effectiveness of the LPC impact damper in damping the vibrations of a multi-degree-of-freedom system under different types of excitations. A prototype of the LPC impact dampers is fabricated and tested in our lab using a three-story frame structure. The experimental outcomes clearly show that the LPC impact damper can effectively attenuate the free and forced vibrations of flexible structures.
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Rasal, Shraddhesh, Shivam Asthana, Vikraman Vellandi, Verónica Santos Arconada, and Guido Tosolin. "Implementation of a Driver-in-the-Loop Methodology for Virtual Development of Semi-Active Dampers." In WCX SAE World Congress Experience. 400 Commonwealth Drive, Warrendale, PA, United States: SAE International, 2024. http://dx.doi.org/10.4271/2024-01-2759.
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<div class="section abstract"><div class="htmlview paragraph">In today’s rapidly evolving automotive world, reduction of time to market has prime importance for a new product development. It is critical to have significant front-loading of the development activities to reduce development time while achieving best in class performance targets. Driver-in-the-loop (DIL) simulators have shown significant potential for achieving it, through real time subjective feedback at preliminary stages of the vehicle development. Recent advances in technology of driving simulators have enabled quite accurate representation steering and handling performance, also good prediction on primary ride and low frequency vibrations.</div><div class="htmlview paragraph">In conventional damper development, the definition of the initial dampers tuning specifications typically requires a mule vehicle, or atleast, a comparable vehicle. However, this approach is associated with protracted iterations that consume substantial time and cost. This becomes even more critical when introducing new damper technology on all new vehicle platform. The proposed virtual development approach using a DIL simulator allows early selection of semiactive valve family and damping forces envelope before physical prototype build.</div><div class="htmlview paragraph">In current development firstly, AMESim based mathematical models of the semi-active dampers were integrated in the full vehicle model running on the driving simulator. A real-time control on damper hydraulic model was established through control logic functions based on virtual sensors feedback integrated into vehicle model<b>.</b> Secondly, virtual tuning loops were conducted where-in expert drivers were able to identify the most suitable semi-active valve and passive damper hardware combination, based on evaluations conducted on several driving scenarios. The controller logic functions, and the pro-active control function parameters were optimized to set-up baseline and tuning direction for physical development.</div><div class="htmlview paragraph">As consequence, the virtual ridework made it possible to set early development directions in terms of desired damping force ranges, valve architecture family and control logic configuration. The virtual tuning loops allowed to significantly reduce the tuning activity compared to the physical sessions. Furthermore, due to availability of fundamental semi-damper setup, provided strong baseline for physical development further expediting it.</div></div>
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Pesterev, Alexander V., and Grigorii A. Tavrizov. "The Method of Trajectories for Finding Eigenfrequencies of Damped Structures." In ASME 1995 Design Engineering Technical Conferences collocated with the ASME 1995 15th International Computers in Engineering Conference and the ASME 1995 9th Annual Engineering Database Symposium. American Society of Mechanical Engineers, 1995. http://dx.doi.org/10.1115/detc1995-0642.
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Abstract The method of finding complex eigenfrequencies of distributed parameter structures with finite number of lumped dampers is presented. The approach used is based upon the structural analysis method in the context of which the problem of investigation of a system degenerates into investigation of some complex characteristic matrix. Multiplication of all damping coefficients by a real scalar parameter α results in consideration of a family of α-parametrized intermediate systems. When α varies eigenfrequencies of the intermediate systems describe trajectories in the complex plane. The differential equation governing the trajectories is established. Given the eigenfrequencies of the conservative system those of the damped structure can be obtained by integrating the differential equation.
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Meisami-Azad, Mona, Farzad A. Shirazi, and Karolos M. Grigoriadis. "Anti-Windup LPV Control Design of MR Dampers for Structural Vibration Suppression." In ASME 2011 Dynamic Systems and Control Conference and Bath/ASME Symposium on Fluid Power and Motion Control. ASMEDC, 2011. http://dx.doi.org/10.1115/dscc2011-6072.
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Magneto-rheological (MR) dampers that belong to the family of semi-active devices are widely used for vibration attenuation in space and civil engineering structures. In this paper, we study the use of MR dampers for seismic protection of a model two-story structure. A modified Bingham model of the MR damper is considered for linear parameter varying (LPV) modeling and control of the system. The main contribution of the paper is the design and experimental validation of an LPV anti-windup compensator to tackle the effect of actuator saturation on control design performance. The designed LPV anti-windup control scheme is advantageous from the implementation standpoint because it can be considered as an addition to the existing control system. Experimental results demonstrate the effective vibration suppression of the structure in the presence of the seismic excitation inputs by utilizing an LPV control strategy. An inner/outer loop control strategy is further developed and implemented considering the actuator saturation effect to reduce the control effort and saving the MR damper power consumption.
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WEINACHT, PAUL. "Navier-Stokes predictions of pitch damping for a family of flared projectiles." In 9th Applied Aerodynamics Conference. Reston, Virigina: American Institute of Aeronautics and Astronautics, 1991. http://dx.doi.org/10.2514/6.1991-3339.
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Chang, Shuenn-Yih, and Chiu-Li Huang. "A Family of Structure-Dependent Integration Methods Enhanced with Favorable Numerical Damping." In 2018 9th International Conference on Mechanical and Aerospace Engineering (ICMAE). IEEE, 2018. http://dx.doi.org/10.1109/icmae.2018.8467699.
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Gastaldi, Chiara, and Muzio M. Gola. "Pre-Optimization of Asymmetrical Underplatform Dampers." In ASME Turbo Expo 2016: Turbomachinery Technical Conference and Exposition. American Society of Mechanical Engineers, 2016. http://dx.doi.org/10.1115/gt2016-57359.
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The numerical coupled optimization of an underplatform damper is the exploration of its dynamics through a finite element model which includes both the damper and the blades. This is an effective approach if the initial damper mass and geometry have been previously selected in such a way that those parameter combinations leading to undesirable damper behavior (i.e. contact point lift-off, jamming, excessive contact forces) are ruled out a priori. This can be obtained through a pre-optimization where, after choosing the damper type the following main steps are followed: 1. ensure that damper jamming is avoided through an appropriate choice of platform angles, in function of the friction coefficients; 2. ensure that damper lift-off is avoided through an appropriate choice of the shape and position of the damper-platform flat contact surface and the position of the damper mass center; 3. set upper and lower limits to the value of damper-platform contact forces (as a multiple of the damper centrifugal force), the first being related to friction and wear problems, the second to the very existence of bilateral contacts; 4. check the model, and in particular the values of friction coefficients and contact stiffness, against experimental results. Once the above knowledge concerning the most desirable damper shape has been gathered an effective coupled-optimization can safely be performed. This is done by finding the most effective match between the damper size/mass and the bladed disk through a non-linear dynamic calculation (not examined in this paper). The outcome of both the pre-optimization and the coupled optimization are strongly dependent on the assumed values of friction coefficients, which depend on the contact surface type (then, different for the left and right side of the damper) and the contact pressure. The paper capitalizes on already developed tools, presented in previous ASME papers, such as the test rig developed by the AERMEC lab to draw the appropriate values of contact parameters, the numerical model representing the stand-alone dynamics of the damper between the platforms and the automatic random sampling tuning procedure. The purpose of the paper is to illustrate the procedure through the analysis of a family of rigid bar dampers with a curved-flat cross section.
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Algrain, Hervé, Calogero Conti, and Pierre Dehombreux. "Separating the Contributions in Localization Methods: A Technique to Enhance Identification of Damping Related Parameters." In ASME 1999 Design Engineering Technical Conferences. American Society of Mechanical Engineers, 1999. http://dx.doi.org/10.1115/detc99/vib-8334.
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Abstract Finite Element Model Updating has for objective to increase the correlation between the experimental dynamic responses of a structure and the predictions from a model. Among different initial choices, these procedures need to establish a set of representative parameters to be updated in which some are in real error and some are not. It is therefore important to select the correct properties that have to be updated to ensure that no marginal corrections are introduced. In this paper the standard localization criteria are presented and a technique to separate the global localization criteria in family-based criteria for damped structures is introduced. The methods are analyzed and applied to both numerical and experimental examples; a clear enhancement of the results is noticed using the family-based criteria. A simple way to qualify the stability of a localization method to noise is presented.
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Li, Lin, Xiaoping Yu, and Peiyi Wang. "Research on Aerodynamic Damping of Bladed Disk With Random Mistuning." In ASME Turbo Expo 2017: Turbomachinery Technical Conference and Exposition. American Society of Mechanical Engineers, 2017. http://dx.doi.org/10.1115/gt2017-63877.
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This paper presents an investigation on the aerodynamic damping of bladed disk (also called ‘blisk’) with mistuning. The study focuses mainly on the mechanism of the effect of random and intentional mistuning on the aero-elastic stability of blisk. For the purpose, aero-elastic stability equations of tuned and mistuned blisk in the frequency domain are established. NASA-Rotor37 is taken as the analysis model. In order to obtain the aerodynamic damping, the unsteady aero-elastic forces are calculated by the double channel harmonic method based on phase correction with aid of the general software CFX. Considering the stochastic characteristics of random mistuning, statistical analysis on the aerodynamic damping of mistuned blisk is performed. The effects of mistuning with different levels are compared. The mechanism of the effects of mistuning on the aero-elastic stability of blisk is found that mistuning couples the modes of different travelling waves and it concentrates the aerodynamic damping in a travelling wave-mode-family by increasing the aerodynamic damping ratios in forward travelling wave modes and decreasing the aerodynamic damping ratios in backward travelling wave modes. And the higher the mistuning level, the more obvious the trend. Furthermore, the following result is obtained: Whatever the mistuning level, in a traveling wave-mode-family, the aerodynamic damping of mistuned blisk is greater than the minimum aerodynamic damping of corresponding tuned blisk and less than the maximum value of it. Besides, the harmonic order of intentional mistuning that can be used to raise the aero-elastic stability of blisk is proposed.
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Cohen, Kelly, Tanchum Weller, and Joseph Ben-Asher. "Fuzzy Logic Control Applications for Second Order Problems With Low Damping." In ASME 2001 International Mechanical Engineering Congress and Exposition. American Society of Mechanical Engineers, 2001. http://dx.doi.org/10.1115/imece2001/ad-23724.
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Abstract A general methodology has been developed for the design of a robust control law for a family of lightly damped second order problems. In this research effort, the passivity approach has been extended to systems having non-collocated input/output pairs by introducing an observer that incorporates the nominal dynamical model of the plant. The developed passive observer-based control law emulates numerous dynamic vibration absorbers which are tuned to a targeted frequency using classical methods and the tuning ratios are time-invariant. However, the uniqueness of this approach is that the damping parameters of the emulated absorbers are continuously varied by means of a fuzzy logic control algorithm to provide near minimum-time suppression of vibration. The developed approach is applied to both several benchmarks in the field of structural dynamics as well as experiments using piezo-ceramic sensors and actuators. Results show that this methodology provides stability and performance robustness on the one hand as well as requiring relatively low amount of actuation authority for desired nominal plant close-loop behavior.
Reports on the topic "Dampier family"
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Weinacht, Paul. Navier-Stokes Predictions of Pitch-Damping for a Family of Flared Projectiles. Fort Belvoir, VA: Defense Technical Information Center, October 1994. http://dx.doi.org/10.21236/ada285923.
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Mazzoni, Silvia, Nicholas Gregor, Linda Al Atik, Yousef Bozorgnia, David Welch, and Gregory Deierlein. Probabilistic Seismic Hazard Analysis and Selecting and Scaling of Ground-Motion Records (PEER-CEA Project). Pacific Earthquake Engineering Research Center, University of California, Berkeley, CA, November 2020. http://dx.doi.org/10.55461/zjdn7385.
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This report is one of a series of reports documenting the methods and findings of a multi-year, multi-disciplinary project coordinated by the Pacific Earthquake Engineering Research Center (PEER) and funded by the California Earthquake Authority (CEA). The overall project is titled “Quantifying the Performance of Retrofit of Cripple Walls and Sill Anchorage in Single-Family Wood-Frame Buildings,” henceforth referred to as the “PEER–CEA Project.” The overall objective of the PEER–CEA Project is to provide scientifically based information (e.g., testing, analysis, and resulting loss models) that measure and assess the effectiveness of seismic retrofit to reduce the risk of damage and associated losses (repair costs) of wood-frame houses with cripple wall and sill anchorage deficiencies as well as retrofitted conditions that address those deficiencies. Tasks that support and inform the loss-modeling effort are: (1) collecting and summarizing existing information and results of previous research on the performance of wood-frame houses; (2) identifying construction features to characterize alternative variants of wood-frame houses; (3) characterizing earthquake hazard and ground motions at representative sites in California; (4) developing cyclic loading protocols and conducting laboratory tests of cripple wall panels, wood-frame wall subassemblies, and sill anchorages to measure and document their response (strength and stiffness) under cyclic loading; and (5) the computer modeling, simulations, and the development of loss models as informed by a workshop with claims adjustors. This report is a product of Working Group 3 (WG3), Task 3.1: Selecting and Scaling Ground-motion records. The objective of Task 3.1 is to provide suites of ground motions to be used by other working groups (WGs), especially Working Group 5: Analytical Modeling (WG5) for Simulation Studies. The ground motions used in the numerical simulations are intended to represent seismic hazard at the building site. The seismic hazard is dependent on the location of the site relative to seismic sources, the characteristics of the seismic sources in the region and the local soil conditions at the site. To achieve a proper representation of hazard across the State of California, ten sites were selected, and a site-specific probabilistic seismic hazard analysis (PSHA) was performed at each of these sites for both a soft soil (Vs30 = 270 m/sec) and a stiff soil (Vs30=760 m/sec). The PSHA used the UCERF3 seismic source model, which represents the latest seismic source model adopted by the USGS [2013] and NGA-West2 ground-motion models. The PSHA was carried out for structural periods ranging from 0.01 to 10 sec. At each site and soil class, the results from the PSHA—hazard curves, hazard deaggregation, and uniform-hazard spectra (UHS)—were extracted for a series of ten return periods, prescribed by WG5 and WG6, ranging from 15.5–2500 years. For each case (site, soil class, and return period), the UHS was used as the target spectrum for selection and modification of a suite of ground motions. Additionally, another set of target spectra based on “Conditional Spectra” (CS), which are more realistic than UHS, was developed [Baker and Lee 2018]. The Conditional Spectra are defined by the median (Conditional Mean Spectrum) and a period-dependent variance. A suite of at least 40 record pairs (horizontal) were selected and modified for each return period and target-spectrum type. Thus, for each ground-motion suite, 40 or more record pairs were selected using the deaggregation of the hazard, resulting in more than 200 record pairs per target-spectrum type at each site. The suites contained more than 40 records in case some were rejected by the modelers due to secondary characteristics; however, none were rejected, and the complete set was used. For the case of UHS as the target spectrum, the selected motions were modified (scaled) such that the average of the median spectrum (RotD50) [Boore 2010] of the ground-motion pairs follow the target spectrum closely within the period range of interest to the analysts. In communications with WG5 researchers, for ground-motion (time histories, or time series) selection and modification, a period range between 0.01–2.0 sec was selected for this specific application for the project. The duration metrics and pulse characteristics of the records were also used in the final selection of ground motions. The damping ratio for the PSHA and ground-motion target spectra was set to 5%, which is standard practice in engineering applications. For the cases where the CS was used as the target spectrum, the ground-motion suites were selected and scaled using a modified version of the conditional spectrum ground-motion selection tool (CS-GMS tool) developed by Baker and Lee [2018]. This tool selects and scales a suite of ground motions to meet both the median and the user-defined variability. This variability is defined by the relationship developed by Baker and Jayaram [2008]. The computation of CS requires a structural period for the conditional model. In collaboration with WG5 researchers, a conditioning period of 0.25 sec was selected as a representative of the fundamental mode of vibration of the buildings of interest in this study. Working Group 5 carried out a sensitivity analysis of using other conditioning periods, and the results and discussion of selection of conditioning period are reported in Section 4 of the WG5 PEER report entitled Technical Background Report for Structural Analysis and Performance Assessment. The WG3.1 report presents a summary of the selected sites, the seismic-source characterization model, and the ground-motion characterization model used in the PSHA, followed by selection and modification of suites of ground motions. The Record Sequence Number (RSN) and the associated scale factors are tabulated in the Appendices of this report, and the actual time-series files can be downloaded from the PEER Ground-motion database Portal (https://ngawest2.berkeley.edu/)(link is external).