Academic literature on the topic 'Pince de suspension'
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Journal articles on the topic "Pince de suspension"
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Wu, Qing, Yan Sun, Maksym Spiryagin, and Colin Cole. "Methodology to optimize wedge suspensions of three-piece bogies of railway vehicles." Journal of Vibration and Control 24, no. 3 (May 3, 2016): 565–81. http://dx.doi.org/10.1177/1077546316645698.
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Wedge suspensions are critical systems for three-piece bogies. This paper proposes a methodology to optimize wedge suspensions using white-box suspension models, dynamic simulations of railway vehicle systems, parallel multi-objective Particle Swarm Optimization (pMOPSO), and parallel multi-objective Genetic Algorithm (pMOGA). Two types of original wedge suspensions with three different toe angle configurations were modeled and compared. Four case studies were carried out to prove the feasibility of the optimization methodology. A series of optimized designs were identified using the Pareto Front technique. Demonstrative optimized designs were compared with the original designs. Results show that wedge suspensions with the toe-in configuration provide better dynamic performance for freight wagons. Significant reductions to the maximum wheel/rail contact forces can be achieved by the optimized designs. Linear speed-up was achieved by using the parallel computing technique.
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Aronen, Tuija, Hely Häggman, and Anja Hohtola. "Transient β-glucuronidase expression in Scots pine tissues derived from mature trees." Canadian Journal of Forest Research 24, no. 10 (October 1, 1994): 2006–11. http://dx.doi.org/10.1139/x94-257.
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Vegetative buds and bud-derived calli and suspension cells from 5- to 50-year-old Scots pines (Pinussylvestris L.) were used as targets for biolistic transformation. The gene construct used in the experiments was 35S CaMV–β-glucuronidase (GUS). The highest average level of transient GUS expression was found in suspension cells: 1229 ± 359 (mean ± SE) expressing cells per million. Transient expression was found in 35 of 44 (79%) tree genotypes studied. The expression level in buds and in calli was low: one or two spots per expressing bud. Growth-regulator pretreatment (BAP and 2,4-D) increased the number of GUS-expressing buds significantly. The high transient expression level in suspensions and the high percentage of GUS-expressing genotypes suggest that mature Scots pine tissues have potential for further transformation and genetic regulation studies.
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Tautorus, T. E., L. C. Fowke, and D. I. Dunstan. "Comparative studies of protoplast development in jack pine (Pinus banksiana)." Canadian Journal of Botany 68, no. 8 (August 1, 1990): 1774–79. http://dx.doi.org/10.1139/b90-229.
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Protoplasts were isolated either from the cotyledons of 8- to 10-day-old seedlings, or from cell suspensions, initiated from seedlings of the same open-pollinated seedlot of jack pine (Pinus banksiana Lamb.). Protoplast yields were 2.0 – 7.0 × 105/g fresh wt. for cotyledon-derived, and 0.3–5 × 105/g fresh wt. for suspension-derived protoplasts. Cotyledon protoplasts (6.8%) divided after 5 to 8 days incubation in liquid Lainé medium C with 450 mM glucose as osmoticum. Small clusters of 6 to 10 cells, which were observed after approximately 2 weeks, formed microcalli upon further dilution of the culture medium. By 6 to 8 weeks, these microcalli could be transferred to solid medium using a nurse culture of jack pine cells. Protoplasts isolated from seven cell suspension lines differed in their responses to culture conditions. First divisions were only observed with two cell lines cultured in either Lainé medium C or one-half Litvay with 370 mM glucose, but this did not lead to callus development. Key words: jack pine, Pinus banksiana, cotyledons, protoplasts, regeneration, callus.
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Sun, Y. Q., and C. Cole. "Comprehensive wagon-track modelling for simulation of three-piece bogie suspension dynamics." Proceedings of the Institution of Mechanical Engineers, Part C: Journal of Mechanical Engineering Science 221, no. 8 (August 1, 2007): 905–17. http://dx.doi.org/10.1243/09544062jmes434.
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A wagon-track dynamics interaction model has been developed to investigate the dynamics of suspensions with friction wedge dampers that are widely used in three-piece bogie wagons in Australia. The wagon is modelled using 66 degrees-of-freedom, accounting for the three-dimensional movements of all wagon components. The mass of the wedge has also been modelled. The track is modelled with rails as Timoshenko beams and discretely supported by the spring and damper elements representing the elasticity of pads, fasteners, and ballast. An assumed track geometry irregularity, i.e. top surface profile, is used for the analysis of suspension dynamics. The simulation results of the wagon-track dynamics interaction model have been compared with those from a VAMPIRE model. The VAMPIRE model uses the normal user level approaches without special subroutine development. Effects of the wedge friction conditions and the effect of track geometry irregularity have been investigated for the better understanding of dynamic performance of three-piece bogie suspensions.
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Huang, Francis L. "Prior Problem Behaviors Do Not Account for the Racial Suspension Gap." Educational Researcher 49, no. 7 (June 11, 2020): 493–502. http://dx.doi.org/10.3102/0013189x20932474.
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At the end of 2018, Obama-era disciplinary guidance aimed at reducing the use of suspensions in schools (especially for minorities and students with disabilities) was revoked by the U.S. Department of Education. A key piece of research supporting the decision was based on the analyses of the Early Childhood Longitudinal Study, Kindergarten Class of 1998–1999 (ECLS-K), which showed that the racial suspension gap was not really about race but resulted from the differential behavior exhibited by Black and White students. We reanalyzed the public-use ECLS-K and provide syntax for our analyses to show that the findings were primarily due to sample selection bias. Several alternative model specifications were tested and continued to show the persistence of the race-based suspension gaps regardless of model or measure used.
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Hong, Zhenyu, Xiaoli Yu, Zhenpeng He, and Guichang Zhang. "The multi-objective optimization of the damaged aircraft trailer based on a dynamic model." Proceedings of the Institution of Mechanical Engineers, Part D: Journal of Automobile Engineering 232, no. 11 (October 23, 2017): 1481–93. http://dx.doi.org/10.1177/0954407017730439.
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A damaged aircraft trailer is an essential piece of airport emergency rescue equipment which is made up of frames and multiple suspensions. As a load–force transferring mechanism, the suspension bears heavy loads which can cause fatigue damage. Therefore, reducing the maximum stress of the suspension is necessary to improve the vehicle performance. Besides, lightweight design should be considered to reduce energy consumption. Thus, lighter suspension which can bear more pressure is the optimization objective of this research. A multi-objective optimization method was carried out to analyze the suspension arm of a damaged aircraft trailer. Firstly, to investigate the dynamic characteristics and the reliability of the damaged aircraft trailer, a detailed three combined damaged aircraft trailers model was built. Based on the flexible-rigid coupled method, dynamic simulation of the damaged aircraft trailer was conducted in MSC.ADAMS. Then a suspension model was established, and the stress under different loads was measured to verify the accuracy of the finite element suspension arm model by experiments. Based on the design of experiment method, the effect of suspension arm parameters were obtained to build the approximate models. Besides, the influences of some effect parameters on optimal objectives were analyzed based on the surface response method. During the optimization process, a non-dominated sorting genetic algorithm II was adopted to optimize the mass and stress of the suspension arm. The results show that the mass of the suspension arm is reduced from 146.81 kg to 126.69 kg, which is a reduction of 14%. The maximum von Mises stress is changed from 325 MPa to 297 MPa, which is a decrease of 8.6%. This optimal method can be extended to the overall vehicle, which has an important significance in the whole damaged aircraft trailer characteristics improvement design.
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Kozeruk, A. S., Y. L. Malpica, M. I. Filonova, V. I. Shamkalovich, and R. O. Dias Gonzalez. "MATHEMATICAL MODELING OF OPERATIONAL ZONE FOR TECHNOLOGICAL EQUIPMENT USED FOR DOUBLE-SIDED PROCESSING OF LENSES." Science & Technique 17, no. 3 (May 31, 2018): 204–10. http://dx.doi.org/10.21122/2227-1031-2018-17-3-204-210.
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A mathematical modeling of geometric and kinematic relations has been made in respect of an operational zone for one of the standard machine tool sections which is used for simultaneous double-sided abrasive processing of highly-accurate lenses with a small rigidity (with a thin centre) under free lapping conditions. An analytical expression has been obtained for calculation of a sliding velocity in an arbitrarily selected point either on a surface to be processed or on a processing surface. As the proposed technology for simultaneous double-sided processing presupposes oscillatory motion of only processing tools then in order to eliminate a joint opening (a local contact fault between lapping surfaces of a tool and a work-piece) length of a drive piece must be not less than a specified value. In this case a convex tool is rigidly connected with a drive piece and it makes a reversing rotary motion (an oscillatory motion) around a centre of the processed spherical surface and a hinged joint of the centre with an output element of the technological equipment actuation mechanism is realized by transition of the drive piece ball end with a spherical seat in the output unit. In order to reveal analytical dependence of tool drive piece length on radius value of the processed spherical lens surface and friction coefficient in the contact zone of the tool and a work-piece the paper has considered a flow pattern of force while processing concave surfaces of lenses having small radius of curvature in case when the tool is positioned at the top. The friction coefficient included in the obtained expression has been determined for grinding while using suspensions of М40, М28, М10 micro-powders in a cast-iron grinding instrument and polishing while using polyrhythm suspension in a pitch and urethane-foam polisher. A method of the inclined plane has been used in this case and following the method a work-piece of optical glass has been initially lapped to the tool with the help of the appropriate abrasive suspension and the required angle has been determined at the moment when the work-piece started its sliding movement along the tool surface.
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Luo, Zhuo, Cheng Yong Wang, and Rong Juan Wang. "Research of Micro-Abrasive Suspension Jet Erosion Morphology and Material Removal Mechanism." Advanced Materials Research 797 (September 2013): 79–84. http://dx.doi.org/10.4028/www.scientific.net/amr.797.79.
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This paper introduces the micro-abrasive suspension jet polishing technology in precision machining technology. In order to understand the micro-abrasive suspension jet erosion morphology and material removal mechanism, the erosion experiments of micro-abrasive suspension jet on 40CrMnMo7 special steel work-piece were taken. We found that when the incident angles are 90°, 60°, 30°, the polishing area is respectively annular shape, horseshoe shape and blade shape. During the erosion process, as the incident angle becomes smaller, most amounts of abrasive particles impact angles will also be small, and these cause more material removal. When the particles impact the work-piece with small angles, most particles play shearing action on the work-piece and leave the work-piece nanoscale scratches; while the particles impact the work-piece at large angles, extrusion and blow are formed by the majority of the particles on the work-piece, leaving different small size pits.
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Château, Joris, Élisabeth Guazzelli, and Henri Lhuissier. "Pinch-off of a viscous suspension thread." Journal of Fluid Mechanics 852 (August 3, 2018): 178–98. http://dx.doi.org/10.1017/jfm.2018.530.
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The pinch-off of a capillary thread is studied at large Ohnesorge number for non-Brownian, neutrally buoyant, mono-disperse, rigid, spherical particles suspended in a Newtonian liquid with viscosity $\unicode[STIX]{x1D702}_{0}$ and surface tension $\unicode[STIX]{x1D70E}$. Reproducible pinch-off dynamics is obtained by letting a drop coalesce with a bath. The bridge shape and time evolution of the neck diameter, $h_{\mathit{min}}$, are studied for varied particle size $d$, volume fraction $\unicode[STIX]{x1D719}$ and liquid contact angle $\unicode[STIX]{x1D703}$. Two successive regimes are identified: (i) a first effective-viscous-fluid regime which only depends upon $\unicode[STIX]{x1D719}$ and (ii) a subsequent discrete regime, depending both on $d$ and $\unicode[STIX]{x1D719}$, in which the thinning localises at the neck and accelerates continuously. In the first regime, the suspension behaves as an effective viscous fluid and the dynamics is solely characterised by the effective viscosity of the suspension, $\unicode[STIX]{x1D702}_{e}\sim -\unicode[STIX]{x1D70E}/{\dot{h}}_{\mathit{min}}$, which agrees closely with the steady shear viscosity measured in a conventional rheometer and diverges as $(\unicode[STIX]{x1D719}_{c}-\unicode[STIX]{x1D719})^{-2}$ at the same critical particle volume fraction, $\unicode[STIX]{x1D719}_{c}$. For $\unicode[STIX]{x1D719}\gtrsim 35\,\%$, the thinning rate is found to increase by a factor of order one when the flow becomes purely extensional, suggesting non-Newtonian effects. The discrete regime is observed from a transition neck diameter, $h_{\mathit{min}}\equiv h^{\ast }\sim d\,(\unicode[STIX]{x1D719}_{c}-\unicode[STIX]{x1D719})^{-1/3}$, down to $h_{\mathit{min}}\approx d$, where the thinning rate recovers the value obtained for the pure interstitial fluid, $\unicode[STIX]{x1D70E}/\unicode[STIX]{x1D702}_{0}$, and lasts $t^{\ast }\sim \unicode[STIX]{x1D702}_{e}h^{\ast }/\unicode[STIX]{x1D70E}$.
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Skrzecz, Iwona, Elżbieta Popowska-Nowak, Robert Wolski, Alicja Sowińska, Tomasz Jabłoński, Elżbieta Pezowicz, Dorota Tumialis, and Iwona Przewłoka. "The role of fungus Beauveria bassiana in reducing the number of Pissodes castaneus (Col., Curculionidae) in young forests." Folia Forestalia Polonica 58, no. 4 (December 1, 2016): 214–19. http://dx.doi.org/10.1515/ffp-2016-0024.
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Abstract Small banded pine weevil Pissodes castaneus is one of the most dangerous pests of Pinus sylvestris plantations and thickets. The lack of effective and environmentally safe methods of limiting the number of the pest justified to undertake the studies aimed at the laboratory and field evaluation of biological activity of entomopathogenic fungus Beauveria bassiana used to reduce the numbers of small banded pine weevil. In laboratory, the beetles were reared on the sections of fresh Scots pine twigs that were treated with five suspensions containing from 1 × 104 to 1 × 108 conidia of B. bassiana in 1 ml. During the 3-week rearing, insect mortality was determined and median lethal concentration LC50 was calculated. The field treatments consisted of spraying 4-year-old P. sylvestris trees with two formulations of fungus containing 1 × 108 conidia ml−1 of suspension. Treatments consisted of spraying 4-year-old P. sylvestris trees with two fungus formulations containing 1 × 108 conidia ml−1. High insecticidal activity of B. bassiana was found because the pathogen caused the death of 14-94% of P. castaneus beetles, LC50 = 6.51 × 105 conidia ml−1. Field treatments did not result in the reduction of plant damage caused by small banded pine weevil; therefore, the spraying of trees with B. bassiana cannot be recommended to protect the young stands of P. sylvestris against pest.
Dissertations / Theses on the topic "Pince de suspension"
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Dalpé, Colombe. "Interaction mécanique entre conducteur électrique aérien et pince de suspension, étude sur la fatigue, la rigidité et la FIP." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 1999. http://www.collectionscanada.ca/obj/s4/f2/dsk1/tape8/PQDD_0002/MQ43808.pdf.
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Ouaki, Bennaceur. "Analyse expérimentale et théorique de l'endommagement par fatigue à pettits débattements des fils de conducteurs électriques au voisinage d'une pince de suspension." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 1998. http://www.collectionscanada.ca/obj/s4/f2/dsk2/tape17/PQDD_0028/NQ36312.pdf.
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Lalonde, Sébastien. "Stratégie de modélisation 3D des solides toronnés appliquée à l'étude de la fatigue des conducteurs de lignes de transport d'énergie électrique." Thèse, Université de Sherbrooke, 2017. http://hdl.handle.net/11143/10497.
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Le vieillissement des lignes de transport d’énergie électrique est une problématique majeure des réseaux. D’ailleurs, des problèmes se posent au plan de l’évaluation de l’état des conducteurs qui, soumis aux vibrations éoliennes, sont vulnérables à l’endommagement en fatigue. Surtout présent aux pinces de suspension, ce phénomène est encore difficile à quantifier, notamment quant à la prédiction de la durée de vie résiduelle des conducteurs.
D’autre part, avec le besoin croissant d’optimiser l’exploitation du réseau tout en maintenant sa fiabilité, une estimation précise de l’état d’endommagement des conducteurs est primordiale. Pour cela, une caractérisation des sollicitations à l’échelle des brins est d’abord requise. L’objectif principal de cette thèse vise donc le développement d’une stratégie de modélisation et d’analyse des conducteurs sollicités en vibrations éoliennes permettant une évaluation précise des conditions de chargement locales à l’échelle des brins, tout en tenant compte de l’effet de la géométrie des pinces de suspension.
Une stratégie de modélisation 3D des solides toronnés est d’abord développée avec la méthode des éléments finis selon une discrétisation individuelle des brins par éléments poutres, capable de traiter toutes les interactions inter-filaires en frottement. Cette modélisation traduit efficacement la cinématique des torons tout en donnant accès aux charges locales. Son caractère général lui permet aussi d’être appliquée à tout problème impliquant des torons.
Appliquée à l’étude des conducteurs sous l’effet des vibrations éoliennes, la stratégie conduit à une description précise de leur comportement tant au plan global en flexion que de la description des contraintes aux brins. Des estimations réalistes de durées de vie en fatigue des conducteurs sont même possibles par l’application de critères d’endommagement aux contraintes.
Ensuite, les pinces de suspension sont intégrées à la stratégie de modélisation selon une représentation surfacique traitant le contact pince/conducteur. Une comparaison à des mesures expérimentales met en relief la précision de l’approche. L’analyse de la solution numérique permet l’identification des zones critiques d’endommagement en contact à chacune des couches du conducteur et révèle des informations nouvelles quant à la nature de la sollicitation des brins à la pince de suspension.
Finalement, des travaux exploratoires proposent un nouveau concept d’analyse multi-échelles en combinant la modélisation numérique d’un système pince/conducteur à des essais de fatigue sur brins individuels. Une mise en œuvre préliminaire de l’approche permet de valider le concept et en jette les bases en vue de son application future.
En somme, la stratégie de modélisation développée dans cette thèse constitue un puissant outil d’analyse qui ouvre maintenant la voie à une caractérisation appropriée de la fatigue des conducteurs en vue ultimement de prédire leur durée et vie résiduelle.Abstract : The aging of overhead transmission lines is a major concern for utilities. In particular, problems arise in assessing the integrity of conductors whose exposure to Aeolian vibrations renders them vulnerable to fatigue damage. Occurring mainly at the suspension clamps, conductor fatigue is still difficult to quantify, especially regarding the prediction of their residual life. With the increasing need to optimize the power grid while maintaining its reliability, accurate evaluations of the conductor damage state become crucial. To this matter, a characterization of the stress levels at the wire scale is first required. The main objective of this thesis is therefore to develop a strategy for the modeling and analysis of conductors subjected to wind induced vibrations, allowing an accurate description of the local load conditions, while accounting for the effects of the suspension clamps. A finite element wire strand modeling strategy is first developed based on a 3D beam element discretization, considering all frictional wire interactions. The modeling approach efficiently reproduces the wire strand kinematics while giving access to the local loads. Its general formulation also allows it to be applied to any problem involving strands. Applied to the study of conductors subjected to Aeolian vibrations, the strategy leads to an accurate description of their behavior at both the global strand deformations and the wire stress description. Realistic conductor residual life estimates are even possible with the use of common damage criteria. The suspension clamps are then incorporated into the modeling strategy using a surface representation of the conductor/clamp contact. Comparisons with experimental measurements highlight the precision of the approach. The model response analysis allows now the identification of the critical damage zones within each conductor layers and reveals new information about the nature of the wire stresses at the suspension clamp. Finally, exploratory works propose a new concept of multi-scale analysis combining the numerical conductor/clamp modeling strategy to experimental fatigue tests on individual wires. A preliminary implementation of the approach validates the concept and lays the foundations for its future application. In summary, the modeling strategy developed in this thesis constitutes a powerful analytical tool which now opens the way to an appropriate characterization of conductor fatigue with the ultimate objective to eventually predict their residual life.
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Eberhardt, Thomas Leonard. "Characterization of lignin deposition in Pinus taeda L. cell suspension cultures." Diss., This resource online, 1992. http://scholar.lib.vt.edu/theses/available/etd-07282008-134210/.
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Choudhury, Tahsin Hassan. "The development of an experimental piece of equipment to monitor the sedimentation of suspensions." Thesis, Imperial College London, 2000. http://hdl.handle.net/10044/1/7556.
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Nealey, Luke T. "The isolation, characterization, and biological testing of xyloglucan from suspension cultured lobloly pine cell spent medium." Diss., Georgia Institute of Technology, 1987. http://hdl.handle.net/1853/5749.
Full textBook chapters on the topic "Pince de suspension"
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Matthys, Robert James. "Solid one-piece suspension springs." In Accurate Clock Pendulums, 131–38. Oxford University Press, 2004. http://dx.doi.org/10.1093/acprof:oso/9780198529712.003.0018.
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MÄKELÄ, KIMMO K. "Characterization and performance of electrorheological fluids based on pine oils." In Electro-Rheological Fluids And Magneto-Rheological Suspensions, 431–43. WORLD SCIENTIFIC, 2000. http://dx.doi.org/10.1142/9789812793607_0050.
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Allison, Penelope M. "Unit I 10,13." In The Insula of the Menander at Pompeii. Oxford University Press, 2007. http://dx.doi.org/10.1093/oso/9780199263127.003.0021.
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Giornali degli Scavi: A,VI,7 (Apr. 1929–Dec. 1935): 175 (15 Apr. 1932); 201–3 (2–7 July 1932); 342–3 (12–13 June 1933). Elia 1934: 340–1. The recording of the excavation for this area is again fairly summary, but reporting the removal of the volcanic deposit below the fallen rafters. It was obviously left partially unexcavated for nearly a year. Present location: unknown, not inventoried at time of excavation. Description: Fragmentary amphora with a black painted inscription on the neck. Inscription:. Present location: unknown, not inventoried at time of excavation. Reference: inscription: Della Corte 1933: 318, no. 339. Discussion: see discussion on amphora. Dimensions: preserved l.: 140 mm. Description: Iron slide key with tapering stem of rectangular section (max. dimensions: 20 mm × 10 mm). Suspension ring (diam.: c.30 mm) and L-shaped bit, with the remains of two teeth. Present location: Pompeii Collection. CB (inv. no. 5057). Discussion: Similar type to cat. no. 136. See discussion on locks and keys. Description: small vase. Present location: unknown, not inventoried at time of excavation. Present location: unknown, not inventoried at time of excavation. Description: base of vase. Present location: unknown, not inventoried at time of excavation. Discussion: excavators recorded that this was found on cat. no. 1914. Dimensions: h.: 0.9 m (GdSc). Description: one amphora is cylindrical with an inscription in black. Present location: unknown, left in situ at time of excavation (inv. no. 5631). Discussion: see discussion on amphora. Present location: unknown, not inventoried at time of excavation. Discussion: see discussion on axes. Dimensions: h.: 248 mm; diam.: 159 mm. Description: Large funnel with a bell-shaped bowl, decorated with incised concentric lines at the carination and on the inside of the rim. Tapering cylindrical funnel, consisting of a folded piece of lamina, soldered to the base of the bowl. The end of the funnel is missing. Preserved brass colour inside rim suggests this was high-quality bronze. Present location: Pompeii Collection, CB (inv. no. 5055). Reference: Tassinari 1993: i.145, and ii.198, 402. Discussion: Tassinari suggested (1993: i.232) that such funnels were for table use. According to White (1975: 124), these were used to decant wine from amphorae into lagoenae.
Conference papers on the topic "Pince de suspension"
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Baruffaldi, Leonardo B., Henrique B. de Arau´jo, and Auteliano A. dos Santos. "A Multibody System Approach to the Wedge Damper Friction Formulation." In ASME 2009 International Mechanical Engineering Congress and Exposition. ASMEDC, 2009. http://dx.doi.org/10.1115/imece2009-11667.
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Secondary suspension of railway three-piece-trucks hasn’t changed much in the past century. Despite this, its most common damping element, the friction wedge, is not yet fully understood. The frictional damping is a known source of non-linearity and non-smoothness that imposes chaotic behaviors to the system, making the mathematical modeling of such devices a difficult task. The present paper presents a multi-body model of a three-piece-truck’s secondary suspension and the results of its simulations with three types of commonly used friction models.
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Ballew, B., B. J. Chan, and C. Sandu. "Three-Piece Half-Truck Multibody Dynamics Models for Freight Train Suspensions." In IEEE/ASME/ASCE 2008 Joint Rail Conference. ASMEDC, 2008. http://dx.doi.org/10.1115/jrc2008-63055.
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A three-piece bogie acts as a support for the freight train car bodies so that they can run on straight and curved tracks. It also absorbs the vibrational energy generated by the track. The three main parts of a traditional three-piece bogie are two side frames and a bolster. The side frames run parallel to the rails and are connected to each other by the bolster, which runs perpendicular to the rail. The side frames are connected to the axles, which are directly connected to the wheels that run on the track through the primary suspension. The primary suspension includes the bearing adapter and pedestal roof. The secondary suspension, which includes the friction wedge and load coils, connects and provides damping on each end of the bolster at its intersection with the side frame. Moreover, the friction wedge aids in warp resistance of the bogie. Because of the wedge’s non-linear frictional characteristics and load sensitive behavior, accurately capturing its dynamics in a computational model proves difficult. Previous work at the Railway Technology Laboratory (RTL) at Virginia Tech focused on better capturing the dynamics of the friction wedge modeled as a 3D rigid body. The current study extends that work to a half-truck model treated as an application of multibody dynamics with unilateral contact to model the friction wedge interactions with the bolster and the side frame. The half-truck model created in MATLAB is a 3D, dynamic, stand-alone model comprised of four rigid bodies: a bolster, two friction wedges, and a side frame assembly. The model allows each wedge four degrees of freedom: vertical displacement, longitudinal displacement (between the bolster and side frame), pitch (rotation around the lateral axis), and yaw (rotation around the vertical axis). The bolster and the side frame have only a vertical translation degree of freedom. The geometry of these bodies can be adjusted for various simulation scenarios. The bolster can be initialized with a pre-defined static yaw (rotation around the vertical axis) and the side frame may be initialized with a predefined pitch/toe geometry (rotation around the lateral axis). The model simulation results have been compared with results from NUCARS®, an industrially used train modeling software developed by the Transportation Technology Center, Inc., for similar inputs.
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Ashtiani, Iman Hazrati, A. K. W. Ahmed, Subhash Rakheja, and Jimin Zhang. "Hunting Characteristics of a Freight Car in Presence of Secondary Suspension Non-Smooth Contact Dynamics." In ASME 2014 International Mechanical Engineering Congress and Exposition. American Society of Mechanical Engineers, 2014. http://dx.doi.org/10.1115/imece2014-38960.
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In this study, the nonlinear damping characteristics of friction wedges in the secondary suspension of a freight truck are investigated considering non-smooth contact, geometry, loss of contact and multi-axis motions. The friction wedge model is integrated to a nonlinear multi-body dynamic model of a three-piece truck to study its hunting characteristics. The 114-degrees-of-freedom model also integrates constraints due to side bearings, axle boxes and center plates, while the wheel/rail contact forces are obtained using FASTSIM algorithm considering non-elliptical contact. The parameters of contact pairs within the suspension are identified to achieve smooth and efficient numerical solutions, while ensuring adequate accuracy. The simulation results are presented to illustrate the hunting properties of the truck in terms of critical speed and oscillation frequency. The results showed subcritical Hopf-bifurcation in the lateral dynamic responses.
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Kodama, Akio, Yasuko Washio, Kumiko Okamoto, and Yugo Osaka. "Water Vapor Adsorption–Desorption Behavior of a Small Piece of Desiccant Rotor in Temperature Swing." In ASME/JSME 2011 8th Thermal Engineering Joint Conference. ASMEDC, 2011. http://dx.doi.org/10.1115/ajtec2011-44591.
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This study aims to clarify the adsorption / desorption behavior of water vapor onto / from a desiccant rotor in temperature swing. A magnetic suspension balance followed time variations of the weight of a small piece of desiccant rotor at various desorption temperature, adsorption / desorption time and their duration time ratio. Adsorption-desorption swing in steady state settled down at certain amplitude of the amount adsorbed keeping the balance of the adsorption and desorption rates averaged over each period. At low regeneration temperature around 40–50°C, adsorption and desorption rates were affected considerably by the change of driving force of adsorption q*-q rather than the temperature dependence of the mass transfer coefficient. At constant adsorption and desorption air conditions, the adsorption /desorption rates could be summarized by the amount of adsorption and temperature, independently of the length of cycle time. Also, region of the amount of adsorption at which adsorption–desorption swing occurred was predicted considering the adsorption / desorption rates – amount adsorbed relationship and the adsorption / desorption duration ratio.
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Deshmukh, Anand P., Danny J. Lohan, and James T. Allison. "Design of a Reconfigurable Dynamic Testbed for Co-Design Method Validation." In ASME 2017 International Design Engineering Technical Conferences and Computers and Information in Engineering Conference. American Society of Mechanical Engineers, 2017. http://dx.doi.org/10.1115/detc2017-67319.
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Physical testing as a technique for validation of engineering design methods can be a valuable source of insights not available through simulation alone. Physical testing also helps to ensure that design methods are suitable for design problems with a practical level of detail, and can reveal issues related to interactions not captured by physics-based computer models. Construction of physical and testing of physical prototypes, however, is costly and time consuming so it is not often used when investigating new design methods for complex systems. This gap is addressed through an innovative testbed presented here that can be reconfigured to achieve a range of different prototype design properties, including kinematic behavior and different control system architectures. Thus, a single testbed can be used for validation of numerous design geometries and control system architectures. The testbed presented here is a mechanically and electronically reconfigurable quarter-car suspension testbed with nonlinear elements that is capable of testing a wide range of both optimal and sub-optimal design prototypes using a single piece of equipment. Kinematic suspension properties can be changed in an automated way to reflect different suspension linkage designs, spring and damper properties can be adjusted in real time, and control system design can be changed easily through streamlined software modifications. While the specific case study is focused on development of a reconfigurable system for validation of co-design methods, the concept extends to physical validation using reconfigurable systems for other classes of design methods.
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Cho, Byung Rae, Young Won Kim, and Jung Yul Yoo. "Lateral Migration of Neutrally-Buoyant Particles in a Square Microchannel at Low Reynolds Numbers." In ASME 2009 Fluids Engineering Division Summer Meeting. ASMEDC, 2009. http://dx.doi.org/10.1115/fedsm2009-78310.
Full textAbstract:
Lateral migration of particles has drawn a lot of attention in suspension community for the last 50 years. Since there is no need for extra external forces, lateral migration of particles plays an important role in constructing microfluidic devices in diverse engineering applications. In this paper, an experimental study on lateral migration of neutrally-buoyant spherical particles transported through a square microchannel is carried out using a fluorescent microscope at low Reynolds numbers. Fluorescent microspheres with diameters of d = 6 μm, 10 μm, and 16 μm are adopted as the test particles, which yield channel-to-particle size ratios of 13.3, 8 and 5, respectively. Spatial distributions of the particles in dilute suspension are visualized at different Reynolds numbers. It is shown that particles are uniformly distributed over the channel cross-section at relatively low Reynolds numbers. As the Reynolds number increases, however, particles migrate inward from the wall and away from the central axis of the channel, so that consequently they accumulate at an equilibrium position, exhibiting the so-called “tubular pinch effect”, first observed by Segre´ and Silberberg as early as in 1962. Experimental results obtained in this work offer design rules for microfluidic channels that play important roles of particle separation or particle focusing.
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Klauser, Peter E. "Modeling Friction Wedges: Part II — An Improved Model." In ASME 2004 International Mechanical Engineering Congress and Exposition. ASMEDC, 2004. http://dx.doi.org/10.1115/imece2004-61095.
Full textAbstract:
Friction wedges are a critical but imperfectly understood component in the typical North American three-piece freight car truck. A companion paper has reviewed the “state-of-the-art” in modeling this crucial suspension element. This paper proposes a new and considerably more complex wedge model. Among the features of the model are the ability to represent shear compliance of the wedge faces and varying normal and tangential pressure distributions on the faces, as well as explicit modeling of column toe-in and toe-out. The model is implemented using the VAMPIRE® vehicle dynamics package developed by AEA Technology plc. Sample results are presented for a standard metal wedge and a design with a resilient pad on the slope surface. Directions for further developments are proposed.
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Vithani, Anand R., Graydon F. Booth, Anand Prabhakaran, Som P. Singh, David C. Brabb, Srinivas Chitti, Monique F. Stewart, and S. K. Punwani. "Freight Truck for Higher Speed Operations." In 2010 Joint Rail Conference. ASMEDC, 2010. http://dx.doi.org/10.1115/jrc2010-36244.
Full textAbstract:
The current freight railroad operations are restricted to a maximum speed of 80 mph partly due to lateral instability of conventional freight trucks at higher speeds. The three-piece truck, a workhorse of the railroad industry for over 100 years, and its variations are susceptible to hunt at 50–55 mph when empty and 90–100 mph in loaded conditions. Design attempts to increase high-speed stability generally lead to diminished curving performance and increased risk of derailment. In this paper we describe a true pendulum suspension based freight truck that is designed to achieve stable operations up to 150 mph without compromising curving performance. The truck’s performance has been analyzed using an industry standard vehicle dynamics simulation tool. The AAR MSRP M-1001 Chapter 11 ‘Service-Worthiness Tests and Analyses For New Freight Cars’ were used to qualify the design where applicable. Traditional tread brakes are supplemented with axle-mounted disc brakes to provide safe braking capabilities beyond 110 mph. Two full-size 70-ton prototypes have been assembled using off-the-shelf and fabricated components. Yard tests have shown that the truck curves properly even under very tight curving conditions.
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Huang, Wei, and Yan Liu. "Unsafe Hunting of Freight Rail Cars." In 2009 Joint Rail Conference. ASMEDC, 2009. http://dx.doi.org/10.1115/jrc2009-63042.
Full textAbstract:
Hunting of rail vehicles refers to self-excited oscillation of truck and carbody. This dynamic instability is due to the conicity of the wheels, the wheel/rail creep forces and the action of the suspensions. Hunting increases wheel/rail wear, causes damage to sensitive lading and in extreme cases can throw the track out of geometry. Furthermore, severe hunting can create unsafe operating conditions that lead to derailments. Although it is widely recognized that truck hunting is not a good thing, it is a fact that many thousands of trucks do hunt on any given day but the number of derailments from hunting are few. So when is the hunting unsafe? Database and parametric studies of unsafe hunting are presented in this paper. The FRA database was used to study the hunting derailments by year, car type, track, speed, load condition, weather and temperature. Parametric studies of hunting and unsafe hunting of three-piece freight cars were conducted based on a large number of measured wheel profiles in combination with worn and new rail profiles. The vehicle, track and operational factors that have the major influence on unsafe hunting are analyzed and the conditions of unsafe hunting presented.
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Tunna, John, Xinggao Shu, and Jeremy Dasher. "Investigation Into the Effects of Geometric Tolerances on Freight Car Dynamics." In ASME 2006 International Mechanical Engineering Congress and Exposition. ASMEDC, 2006. http://dx.doi.org/10.1115/imece2006-14445.
Full textAbstract:
When a 3-piece truck is assembled there are clearances between components that are intended to allow relative movement, and to limit excessive movement. The magnitudes of the clearances are affected by manufacturing tolerances and wear in service. They have important effects on freight car dynamics including hunting stability and curving performance. A study has been made of the effect of varying clearances on the dynamic performance of a typical freight vehicle. The clearances that have been considered are in the areas of the: • sideframe window, • pedestal and bearing adapter • gibs • wheel diameters Combinations of maximum and minimum allowable tolerances and maximum allowable wear have been modeled with TTCI's NUCARS™ simulation software. Most of the test cases in the Association of American Railroads Manual of Standards and Recommend Practices, Chapter XI (1) have been studied. Results were produced from a NUCARS™ model of a 100 ton coal hopper. Empty and loaded simulations were performed. The trucks were modeled with variable load friction wedges. Conclusions have been drawn on the appropriateness of the currently allowable tolerances and wear limits. A new tolerance is suggested for the center of the sideframe window relative to the centerline of the pedestals. The conclusions only apply to the specific vehicle, suspension type and truck type analyzed. This work was sponsored by the Association of American Railroads, Strategic Research Initiative program.