Literatura académica sobre el tema "Ring expension"
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Artículos de revistas sobre el tema "Ring expension"
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Kozu, H., Y. Jumonji, C. Yamazaki, Y. Shoji, S. Hashimoto y A. Ando. "A crowbarless power supply for klystrons". Journal of Synchrotron Radiation 5, n.º 3 (1 de mayo de 1998): 374–75. http://dx.doi.org/10.1107/s0909049597015331.
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A new crowbarless power supply is to be installed at the New SUBARU storage ring. A high-power switching inverter unit eliminates the need for expensive and unstable crowbar circuits for the klystron power supply. It also realizes a very small voltage ripple in the low-frequency region. This is an important characteristic, especially in a quasi-isochronous storage ring such as New SUBARU.
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Thul, Mayur, Yao-Peng Wu, Yi-Jyun Lin, Shu-Lin Du, Hsin-Ru Wu, Wen-Yueh Ho y Shun-Yuan Luo. "Ionic Liquid Catalyzed Per-O-Acetylation and Benzylidene Ring-Opening Reaction". Catalysts 10, n.º 6 (8 de junio de 2020): 642. http://dx.doi.org/10.3390/catal10060642.
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Tunable aryl imidazolium ionic liquids acting as Brønsted acid ionic liquids were found to be efficient catalysts for per-O-acetylation and reductive ring opening of benzylidene acetals. This method requires a truly catalytic amount of the least expensive available ionic liquids that are water-stable and reusable and also stable at room temperature. The reactions were obtained in one hour with good to excellent yields. These reactions can form C−O and C−H bonds with a high atom economy. Furthermore, the ionic liquid is an anomeric selective catalyst in per-O-acetylation and reductive ring opening of benzylidene acetals of sugar moieties.
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Chaudhary, MilindM. "Diamonds are expensive, rings are not: Mastering the paradoxical evolution of nonunion treatment". Journal of Limb Lengthening and Reconstruction 5, n.º 2 (2019): 51. http://dx.doi.org/10.4103/jllr.jllr_24_19.
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Krause, Cornelia y Hubert Morin. "Impact of spruce budworm defoliation on the number of latewood tracheids in balsam fir and black spruce". Canadian Journal of Forest Research 25, n.º 12 (1 de diciembre de 1995): 2029–34. http://dx.doi.org/10.1139/x95-219.
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The influence of spruce budworrn (Choristoneurafumiferana (Clem.)) defoliation was analysed at different stem heights by counting the number of latewood tracheids and measuring tree-ring width. The total height of the tree was divided into three different equal parts: the lower, the middle, and the upper sections of the total stem length. However, only the results of the lower and the upper sections will be presented in this paper. The reduction of ring widths started in the upper part for the living crown and continued downwards to the stem base (0 m) with a delay of 1–2 years. The number of latewood tracheids generally showed a reduction 1 year earlier than the ring widths, particularly in the crown, but also in the other parts of the stem. Considering this, we think that the reduction of the number of latewood tracheids may date the beginning of spruce budworm defoliation more accurately and present a better characterization of the first impact of spruce budworm than the measuring of the ring widths. This parameter will be particularly helpful (when expensive equipment, such as a densitometer or an image analysis system cannot be used) in detecting past outbreaks in the tree-ring records, especially when defoliation records are missing and when the reduction of the ring widths is not very pronounced.
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Wang, Lily, Serge Payette y Yves Bégin. "Relationships between anatomical and densitometric characteristics of black spruce and summer temperature at tree line in northern Quebec". Canadian Journal of Forest Research 32, n.º 3 (1 de marzo de 2002): 477–86. http://dx.doi.org/10.1139/x01-208.
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Tracheid cell number, cell diameter, and cell-wall thickness of black spruce (Picea mariana (Mill.) BSP) tree rings at the tree line (northern Quebec, Canada) were measured using image analysis. The densitometric data from the same samples were used to evaluate the features of image analysis. The anatomical data were correlated with summer temperature variables, including: means of pentad temperature (five consecutive days), growing season (May- September), sum of degree-days, and number of frost-free days. Our results suggest that the main cause of the pale appearance of light rings is thinner latewood cell-wall thickness. Some latewood variables are strongly correlated with corresponding indices for ring cell number and diameter, and ring cell wall thickness. Anatomical ring cell number and the sum of cell diameters (ring widths) were correlated to tree-ring width parameters derived from densitometry. Ring cell number and annual sum of cell diameter also showed very similar trends with both chronologies, suggesting that ring-width length may depend on the number of cells within a ring. Ratio diagram of double cell-wall thickness to cell radial diameter showed similar trend to wood density profile. There is a statistically significant correlation between maximum density and the highest annual ratio between cell wall thickness and lumen diameter. Cell-wall thickness was significantly correlated to maximum density, and both were significantly correlated with summer temperature variables. Our results suggest that wood anatomy may be used as a substitute to densitometry for climate reconstruction as densitometric data require expensive equipments. Also the anatomical method allows the recording of intra-annual information for dendroecological purposes.
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Zafar, Mohsin, Karl Kratkiewicz, Rayyan Manwar y Mohammad Avanaki. "Development of Low-Cost Fast Photoacoustic Computed Tomography: System Characterization and Phantom Study". Applied Sciences 9, n.º 3 (22 de enero de 2019): 374. http://dx.doi.org/10.3390/app9030374.
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A low-cost Photoacoustic Computed Tomography (PACT) system consisting of 16 single-element transducers has been developed. Our design proposes a fast rotating mechanism of 360o rotation around the imaging target, generating comparable images to those produced by large-number-element (e.g., 512, 1024, etc.) ring-array PACT systems. The 2D images with a temporal resolution of 1.5 s and a spatial resolution of 240 µm were achieved. The performance of the proposed system was evaluated by imaging complex phantom. The purpose of the proposed development is to provide researchers a low-cost alternative 2D photoacoustic computed tomography system with comparable resolution to the current high performance expensive ring-array PACT systems.
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ISLAM, SYED S. y A. F. M. ANWAR. "SPICE MODEL OF AlGaN/GaN HEMTs AND SIMULATION OF VCO AND POWER AMPLIFIER". International Journal of High Speed Electronics and Systems 14, n.º 03 (septiembre de 2004): 853–59. http://dx.doi.org/10.1142/s0129156404002946.
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SPICE model parameters are extracted from reported experimental data. The model is implemented in the Cadence Affirma Analog Circuit Design Environment and Spectre simulator is used to simulate class-E power amplifier and ring voltage controlled oscillator (VCO) circuits. The availability of the SPICE model for GaN HEMTs ensures optimization of analog/RF circuits before an expensive cut-and-try method is employed.
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Straže, Aleš, Klemen Novak y Katarina Čufar. "Quality and Price of Spruce Logs, Determined Conventionally and by Dendrochronological and NDE Techniques". Forests 13, n.º 5 (7 de mayo de 2022): 729. http://dx.doi.org/10.3390/f13050729.
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We examined valuable log assortments of Norway spruce (Picea abies) from a traditional auction in Slovenia where spruce growth on many sites is affected by climate change. From 6620 logs, we selected 817 that obtained the highest prices. Factors including log dimensions and geometry, tree-ring characteristics, quality grades according to the standard, properties measured by NDE stress wave testing, and their combined effect on price were modelled. The results showed that half of the auctioned logs were of highest quality (Q1, Q2), with diameters over 60 cm. These logs were more expensive than the thinner logs of lower quality (Q3, Q4). The quality class of the logs, determined by their external features and geometry, was associated with tree-ring and acoustic characteristics. The artificial neural network model (ANN) with feed-forward backpropagation using tree-ring data, longitudinal stress wave velocity, and damping showed that more than 75% of the logs could be accurately classified into quality classes. On the other hand, tree-ring data and acoustic characteristics could not adequately explain the price offered at auction, which probably also depends on unidentified individual requirements and the needs of the buyer.
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Gusev, A. S., C. B. Danilenko, S. A. Starodubtseva y V. Ya Teteryatnikov. "Dynamics of a "Hamster Wheel" Test Bench". Proceedings of Higher Educational Institutions. Маchine Building, n.º 5 (746) (mayo de 2022): 3–9. http://dx.doi.org/10.18698/0536-1044-2022-5-3-9.
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Ground tests of vehicles such as cars and tractors, including life tests and functional tests, are expensive and time-consuming. We propose to replace them with relatively inexpensive time-saving tests using a "hamster wheel" test bench. The vehicle inside a rotating ring remains at rest relative to the ground but in motion relative to the inner surface of the ring. This surface can be equipped with artificial obstacles to simulate actual road irregularities. We constructed differential equations of motion for the system and established the nature of the relative motion involving the outer ring and the test object, taking into account resonance phenomena and possible self-oscillations. We selected a disk simulating a vehicle wheel as our computational scheme. We studied the probability that self-oscillations appear in the system and determined their amplitude. We performed a qualitative assessment of possible dynamic effects. The paper proposes a system for arranging artificial obstacles on the inner surface of the wheel to simulate road bumps in terms of statistics.
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Deans, Douglas. "Effect of Openings in Ring-Reinforced Shells". Marine Technology and SNAME News 27, n.º 01 (1 de enero de 1990): 56–64. http://dx.doi.org/10.5957/mt1.1990.27.1.56.
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The ring-reinforced shell is a primary structure used in the marine and industrial world. Stress and buckling analysis of such structures is generally based on axisymmetric analysis wherein all openings in the shell are neglected. In real life, such structures have a large number of openings often made in a random manner. In order to design an appropriate reinforcement at such an opening, it is necessary to carry out a detailed local stress analysis. Such an analysis can be made either through the use of part models or by superelements which include the entire structure, as well as the local reinforcement. Zoom analysis using the whole model is expensive and requires knowledge of multilevel super element techniques. Analysis using part models is cheaper and can be equally reliable. This paper investigates the effects of openings on the stress distribution in ring-reinforced shells, such as submarines, using a finite element model. The stress concentration factors (SCF's) in areas adjacent to the opening are determined from this analysis. Using these SCF's, modeling rules for utilization of part models are developed and recommended for use.
Tesis sobre el tema "Ring expension"
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Cormier, Gabriel. "Réaction domino photochimique pour la synthèse d'hétérocycles soufrés". Electronic Thesis or Diss., université Paris-Saclay, 2025. http://www.theses.fr/2025UPASF003.
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Les réactions photochimiques constituent un outil puissant pour créer de la diversité moléculaire en chimie organique. A partir de substrats simples et d'un photon, elles permettent de donner accès à des structures moléculaires complexes qu'il serait difficile d'obtenir avec des méthodologies plus classiques. Ces transformations induites par l'absorption de la lumière sont particulièrement intéressantes dans le contexte du développement durable et peuvent participer à relever ce défi plus efficacement lorsqu'elles sont incorporées dans des processus domino. En effet, combinée avec des réactions thermiques ou mieux encore avec d'autres transformations photochimiques, cette stratégie est économe en temps, en énergie et en déchets et peut éviter d'isoler des intermédiaires intrinsèquement instables. Ces cascades photochimiques permettent en outre d'accroitre de façon notable la complexité moléculaire des composés obtenus.Parmi les chromophores possédant un état excité hautement réactif, générés par l'absorption d'un seul photon, les composés thiocarbonylés précurseurs des thiétanes via la réaction de thia-Paternò_Büchi avec un partenaire alcène ont été sous-exploités et la plupart des études impliquant ces dérivés datent de plusieurs décennies. La raison majeure de ce faible développement réside dans la grande instabilité des thiocétones et des thioaldéhydes. Durant cette thèse, il a été décidé de réinvestir la photochimie des thiocarbonyles stables et instables, dans le cadre de réactions domino pour la synthèse de nouveaux squelettes thiétaniques ainsi que pour leurs post-fonctionnalisations photochimiques. Afin de contrer l'instabilité intrinsèque des thiocarbonyles et de permettre leur utilisation dans leurs états excités, singulet ou triplet, nous avons tiré profit de la réaction de fragmentation de Norrish-II de sulfures de phénacyles et de pyrénacyles pour les générer in-situ et ainsi les engager dans d'autres transformations induites par la lumière au sein de cascades photochimiques.Dans ce cadre, nous avons tout d'abord combiné la fragmentation de Norrish-II des sulfures de phénacyles et la réaction de thia-Paternò_Büchi en présence de partenaires alcènes appauvris en électrons et ainsi obtenu une grande bibliothèque de thiétanes (37 exemples) sous irradiation UV. Puis, grâce aux nouvelles propriétés photosensibilisatrices du 1-acétylpyrène, un sous-produit formé par la fragmentation des sulfures de pyrènacyles sous lumière visible, cette même cascade photochimique a pu être développée en présence d'alcènes enrichis en électrons et a permis d'accroitre la liste de nouveaux thiétanes (26 exemples). Un troisième projet décrit la post-fonctionnalisation photochimique des thiétanes dans une réaction inédite d'agrandissement de cycle et la synthèse régiosélective de motifs dithianes par l'incorporation d'un motif thiocarbonyle généré in-situ (17 exemples). Enfin, une quatrième cascade photochimique a été mise en place impliquant une fragmentation de Norrish-II, une réaction de thia-Paternò_Büchi, un agrandissement de cycles thiétanes par un intermédiaire thiocarbonyle, puis enfin une contraction du dithiane pour conduire à la synthèse de tétrahydrothiophènes (7 exemples). Dans ce dernier cas, la réaction domino met en jeu quatre transformations photochimiques successives.Ces cascades photochimiques impliquant les motifs thiocarbonyles ont ainsi permis, à partir de sulfures de phénacyles ou de pyrénacyles et par irradiation à la lumière UV ou visible, de synthétiser les hétérocycles soufrés à quatre, cinq et six chaînons que sont les thiétanes, les tétrahydrothiophènes et les dithianesPhotochemical reactions constitute a powerful tool for the creation of molecular diversity in organic chemistry. From a simple starting material and a photon, they provide access to complex molecular structures that would be difficult to obtain with classical methodologies. These transformations induced by light absorption are particularly attractive in the context of sustainable development and they can address this challenge more effectively when they are incorporated into domino processes. Indeed, combined with thermal reactions or even better with other photochemical transformations, this strategy is economical in terms of time, energy, waste and can avoid the isolation of intrinsically unstable intermediates. These photochemical cascades also allow to significantly increase the molecular complexity of the obtained compounds.Among the chromophores possessing a highly reactive excited state generated by the absorption of a single photon, thiocarbonyl compounds, precursors of thietanes via the thia-Paternò_Büchi reaction with an alkene partner, have been underexploited and most studies involving these derivatives date from several decades ago. The main reason for this weak development is due to the huge instability of thioketones and thioaldehydes. During this PhD thesis, it has been decided to reinvest the photochemistry of stable and unstable thiocabonyls in the frame of domino sequences for the synthesis of new thietane scaffolds and their photochemical post-functionalization. To tackle the intrinsic instability of thiocarbonyls and to allow their use in excited state, singlet or triplet, we took advantage of the Norrish-II fragmentation of phenacyl or pyrenacyl sulfides to generate them in-situ and to engage then into other light-induced transformations within photochemical cascades.In this purpose, we first combined the Norrish-II fragmentation of phenacyl sulfides and the thia-Paternò_Büchi reaction in the presence of electron-withdrawing alkene partners to obtain a large library of thietanes (37 examples) under UV irradiation. Then, thanks to the new photosensitizing properties of the 1-acetylpyrene, a by-product formed during the fragmentation of pyrenacyl sulfides under visible light, the same photochemical cascade has been developed in the presence of electron-realizing alkene partners to enlarge the collection of unprecedented thietanes (26 examples). A third project describes the photochemical post-functionalization of thietanes in a new regioselective ring enlargement for the synthesis of dithiane scaffolds by the incorporation of in-situ generated thiocarbonyls (17 examples). Finally, a fourth photochemical cascade procedure has been described involving a Norrish-II fragmentation, a thia-Paternò_Büchi reaction, a ring enlargement of the thietane core by a thiocarbonyl intermediate and then a contraction of dithiane to allow the synthesis of tetrahydrothiophenes (7 examples). In the latter case, the domino reaction involves four successive photochemical transformations.From phenacyl or pyrenacyl sulfides and by UV or visible light irradiation, these photochemical cascades involving thiocarbonyl units provided access to four, five and six-membered ring sulfur heterocycles: thietanes, tetrahydrothiophene and dithianes, respectively
Capítulos de libros sobre el tema "Ring expension"
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Won, Jin-Myung, Alice Malisia y Fakhreddine Karray. "Reliable Network Design Using Hybrid Genetic Algorithm Based on Multi-Ring Encoding". En Computational Intelligence in Expensive Optimization Problems, 609–35. Berlin, Heidelberg: Springer Berlin Heidelberg, 2010. http://dx.doi.org/10.1007/978-3-642-10701-6_23.
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Taber, Douglass F. "Advances in Alkene Metathesis: The Hoveyda Synthesis of (+)-Quebrachamine". En Organic Synthesis. Oxford University Press, 2013. http://dx.doi.org/10.1093/oso/9780199965724.003.0030.
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There are two major impediments to scaling up alkene metathesis: reducing the amount of the expensive Ru catalyst required, and minimizing residual Ru in the product. Robert H. Grubbs of Caltech developed (Organic Lett. 2009, 11, 1261) a family of silica-supported Ru complexes, exemplified by 1. At 0.75 mol % of 1, the rate of cyclization of 2 to 3 was maintained over eight cycles. The solution of product 3 showed < 5 ppb Ru. Hassan S. Bazzi and David E. Bergbreiter of the Texas A&M campuses in Qatar and College Station also reported (Organic Lett. 2009, 11, 665) a durable polymer-bound Ru metathesis catalyst that maintained its activity over many cycles. Most metathesis catalysts are strongly E selective. Amir H. Hoveyda of Boston College designed (J. Am. Chem. Soc. 2009, 131, 3844) a chiral Mo catalyst that was both highly enantioselective and strongly Z selective, converting the prochiral 4 into the alkene 6. Professor Hoveyda also took advantage (J. Am. Chem. Soc. 2009, 131, 8378) of the known propensity of Ru metathesis catalysts for H bonding, showing that metathesis of the prochiral cyclopropene 7 proceeded with remarkable diastereocontrol. This appears to be a generally useful protocol for assembling enantiomerically pure alkylated quaternary stereogenic centers. It is also possible to encapsulate the Ru catalyst. Ned B. Bowden of the University of Iowa pioneered the use of PDMS thimbles for this purpose. He has now shown (Organic Lett. 2009, 11, 33) that by subsequently adding AD-mix, cross-metathesis can be followed directly by enantioselective dihydroxylation. Ring-opening cross-metathesis of an unsymmetrical alkene such as 13 could give two different products. Alberto Avenoza and Jesús H. Busto of the Universidad de La Rioja established (J. Org. Chem. 2009, 74, 1736) that by tuning the electronic nature of the participating alkene, either product can be obtained with high selectivity. Metathesis can be used to close larger rings. Conformational effects are important. Motoo Tori of Tokushima Bunri University observed (Tetrahedron Lett. 2009, 50, 2225) that although 18 cyclized efficiently, the other three precursors that were diastereomeric on the cyclopentane ring did not undergo ring-closing metathesis.
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Dobson, Eleanor. "‘Fairy tales’ and ‘bunkum’: Marie Corelli, Artefacts and Fabrications". En Writing the Sphinx, 59–96. Edinburgh University Press, 2020. http://dx.doi.org/10.3366/edinburgh/9781474476249.003.0003.
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This chapter centres on the spectral stories and rumours which orbited ancient Egyptian artefacts in the possession of literary authors, along with the Egyptological connections such authors made. It focuses on Marie Corelli, her one-time friend Oscar Wilde, reading Wilde’s scarab ring that recalled the rare and expensive objects in his own writings as finding a literary counterpart in Corelli’s The Sorrows of Satan (1895). Corelli’s devil is Wilde’s double, Wilde’s scarab ring represented as a live beetle within which resides the soul of a mummified princess. Such a depiction, this chapter claims, reflects Corelli’s condemnation of Wilde, and decadence more broadly. Also considered is a necklace that Corelli was given by Sir John Aird, partially comprised of ancient Egyptian beads. This object’s renderings in a heretofore neglected archival source along with Corelli’s lifelong companion’s memoirs, illuminate her belief that ancient Egyptian jewellery allowed spiritual connections between the ancient and modern worlds. Ultimately, this chapter unearths how Corelli, proposing that she was a reincarnated Egyptian princess, fashioned herself as an alternative Egyptological authority at odds with masculine, scholarly Egyptology represented by figures such as E. A. Wallis Budge of the British Museum.
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Parry, Jonathan. "The Ring of Steam, the Lands of Islam, and the Search for Order". En Promised Lands, 298–333. Princeton University Press, 2022. http://dx.doi.org/10.23943/princeton/9780691181899.003.0011.
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This chapter addresses Britain's strategies for promoting order along the southern and eastern borders of the Ottoman Empire where it had naval authority. It underlines that disorder and instability would be bad and expensive in themselves, and the only means by which other powers might upset the status quo. The chapter also focuses on the most continuously challenging problem: the border between the Ottoman and Persian empires, which Britain attempted to stabilise in conjunction with Russia, in order to defuse the entrenched hostility between these two political and religious foes. It highlights that this was an example of Aberdeen's Tory strategy of working with Russia to secure global peace and the tensions that frequently arose between Britain and the Ottoman Empire during these years. Ultimately, the chapter investigates how Britain found Ottoman behaviour in the region much more of a challenge than Russian or French activity. In the Gulf and around Aden, the Ottoman claims were defeated. To an outsider, Britain's behaviour on the Middle Eastern waterways cannot have seemed any less assertive than Russia's behaviour in its Balkan sphere of influence.
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Mahmood, Moghal. "The Will". En The Silence That Speaks, 83—C7.P51. Oxford University PressDelhi, 2022. http://dx.doi.org/10.1093/oso/9780190132613.003.0008.
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Abstract Moghal Mahmood “The Will” is written from the perspective of Tahira, the woman whose job it is to bathe dead bodies. She is summoned to Nishat Manzil where the old begum has just died. The custom at deaths in the haveli is that the ghassalni who bathes the corpse will be given whatever is on the body of the deceased at the time of death. Tahira looks at the expensive tops that the begum is wearing in her ears and the big diamond in her ring. She begins to plan ahead for her daughter’s wedding which will become possible if she gets this jewellery. She eagerly prepares the ingredients for the begum’s last bath and waits for the dead woman’s daughters to tell her to begin. But the will has to be read out first. The shroud sealed in a wax cloth, with lines from the Koran written on it in saffron ink is unwrapped and the envelope with the begum’s will is opened. What follows is a startling twist that takes the story onto a different trajectory and gives it an unexpected ending. Translation from Hindi by Sara Rai
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Rodriguez Lucatero, Carlos. "Application of Discrete Mathematics for Programming Discrete Mathematics Calculations". En New Trends in Combinatorics - Theory, Algorithms, Applications [Working Title]. IntechOpen, 2022. http://dx.doi.org/10.5772/intechopen.102990.
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In the discrete mathematics courses, topics, such as the calculation of the element in any position of a sequence of numbers generated by some recurrence relation, calculation of multiplicative inverses in algebraic ring structures modulo a number n, obtaining the complete list of combinations without repetition, for which you can take advantage of the computing power of computers and perform such calculations using computer programs in some programming language. The implementations of these calculations can be carried out in many ways and therefore their algorithmic performance can be very varied. In this chapter, I propose to illustrate by means of some Matlab programs, how the use of results of the same discrete mathematics allows to improve the algorithmic performance of said computer programs. Another topic addressed in regular discrete mathematics courses where calculations arise that could become very expensive both in time and in occupied space, if the calculations are implemented directly from the definitions is modular arithmetic. Such calculations can be carried out much more efficiently by making use of results from discrete mathematics and number theory. The application of these ideas will be developed in the following sections of this chapter.
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Edstrom, Brent. "Digital Signal Processing". En Sound & Music Projects for Eurorack and Beyond, 87–108. Oxford University PressNew York, NY, 2024. http://dx.doi.org/10.1093/9780197514504.003.0008.
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Abstract This chapter cites that audio signals can be processed on the Teensy platform in the form of digital signal processing (DSP). Unlike the expensive analog processors of yore, Teensy microcontrollers can do the job with better fidelity and for a modest cost. The Teensy platform allows the developing of unique processing units that can function as a component of a Eurorack setup, live rig, or guitar effects pedal. The chapter elaborates on the use of two DSPs from the Teensy Audio Library and the creation of two custom DSPs that are not currently available in the library. It also mentions that advanced users can roll their DSPs, opening the door to many possibilities for custom effects.
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Jones, G. R. y I. H. Munro. "Biological spectroscopy using low energy (VUV/UV) synchrotron radiation". En Structure and Dynamics of Biomolecules: Neutron and Synchrotron Radiation for Condensed Matter Studies, 305–37. Oxford University PressOxford, 2000. http://dx.doi.org/10.1093/oso/9780198504535.003.0015.
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Abstract Synchrotron radiation (SR) storage rings provide the most highly collimated and intense continuous sources of X-rays, soft X-rays and extreme vacuum ultraviolet (UV) radiation. At longer wavelengths, in the UV, visible and infrared the photon flux of SR is often surpassed by alternative (usually less expensive) sources, such as lasers, arc lamps, blackbody sources, etc. However, there are inherent properties of synchrotron light that make it the preferred source for many experiments. Synchrotron light from bending magnets provides a wavelength continuum of highly collimated, linearly polarized radiation, emanating from a tiny source (of from 103 to ∼ 106 gm2 in cross-section) of electrons or positrons with a well-understood time structure and long term stability. This unique ensemble of properties is further augmented at third generation synchrotron radiation sources by the much higher flux and brightness available from insertion devices such as undulators or multipole wigglers.
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"Synthetic Methods for Primary Anilines". En Methods and Strategies for C–N Bond Formation Reactions, 145–221. Royal Society of Chemistry, 2023. http://dx.doi.org/10.1039/bk9781837672615-00145.
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Aryl amines have received significant interest because these compounds widely exist in the structural backbones of ligands, pharmaceuticals, agrochemicals, natural products, and functional materials. In N-arylation reactions, several types of organic electrophile coupling partners such as (pseudo)halides (Ullmann-type and Buchwald–Hartwig couplings) and boronic acids (Chan–Lam coupling) are popular. The main synthetic methods for the preparation of these compounds involving N-arylation utilize aryl halides. Progress has been made with the coupling of arylating reagents which are less expensive than aryl halides, providing both a cost-effective and more efficient reaction route. For example, the process of C–H bond activation/functionalization, a step-efficient and atom-economical transformation, has emerged as a powerful strategy in C–N bond-forming reactions. Moreover, a transition-metal-free method for the N-arylation of amines using an aryne intermediate has been developed. This chapter focuses on recent advances in chemo- and regioselective N-arylation (either on one N-center or on the exocyclic N-site of the ring) or the selective arylation of amino alcohols without additional protection/deprotection using arylating reagents. This chapter provides an overview of arylating reagents for N-arylation reactions found in both basic and applied chemical research. The substrate scope, limitations, reaction mechanism, and chemoselectivity, as well as related control strategies of these reactions, are discussed. To the best of our knowledge, there has been no book about introducing arylating reagents to develop more efficient and environmentally friendly cross-coupling methods for the N-arylation of amines. We believe this critical review will provide necessary background information on the N-arylation of amines.
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Joshi, Soham y Raaghav Malik. "A multipurpose robotic glove designed to teach sign language through guided manual motions". En Proceedings of the 2021 International IEMS Conference, March 15-16, 2021, 84–91. Wichita State University, 2021. http://dx.doi.org/10.62704/10057/24730.
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Projections show the numbers of deaf and deafblind individuals are quickly increasing, as both the number of deaf and blind individuals are expected to double within the next 50 years. Additionally, there is limited support for deafblind individuals, as they have little sensory access to the world. Most existing solutions are inadequate because they are either not portable, readily accessible or are very expensive. The goal of our project is to create a low cost, accessible solution for those with these disabilities: a portable device that utilizes the sense of touch to teach sign language, instead of conventional sign language learning methods that rely on sight. By doing this, a more immersive and personalized experience is created. The implementation of this solution is two-pronged: first, the physical portion of the solution is equipped with servo motors that control the pulling and release of a cord threaded through rings on the fingers that moves the user's hands into various sign language positions, which is closely modeled after human hand anatomy. Secondly, feasibility is determined for an AI algorithm to take in data from an external camera to efficiently add new signs to the glove, and also to track the user's sign language patterns and rate the user's accuracy with various signs. Through these mechanisms the user is engaged in learning new signs and expanding their sign language vocabulary, all without their sense of sight. We were successful in creating a working prototype analyzed through hand-tracking mechanisms, and achieving a 91-92% accuracy for the American Sign Language alphabet.
Actas de conferencias sobre el tema "Ring expension"
1
Tibbits, Patrick A. "Effect of Pillow Block Deformation on Ball Bearing Load Distribution". En ASME 2004 International Design Engineering Technical Conferences and Computers and Information in Engineering Conference. ASMEDC, 2004. http://dx.doi.org/10.1115/detc2004-57729.
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Support structure deflection distorts bearing rings, redistributes loads over bearing balls, and affects bearing life. In this study, solid finite elements modeled a shaft, bearing inner ring, outer ring, and pillow block. A nonlinear spring element represented each of the bearing balls. The force-versus-deflection curve of the spring element modeled the variable stiffness of the ball/raceway Hertzian contact. The curve also incorporated the diametrical clearance of the bearing to determine if each ball contacted the raceways. Further modification of the curve compensated for the compliance of the nodes of solid elements that modeled raceways. This construct avoided computationally expensive surface-to-surface contact calculations. Program output included deflection of the pillow block and a listing of spring element forces, which characterized the ball loads. The maximum ball load decreased for a bearing installed in a pillow block, and life increased. Material or geometric changes that reduced pillow block stiffness further improved life.
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El-Shafei, Aly, Mohamed S. Ibrahim y Antoine S. Dimitri. "Experimental and Analytical Stability Investigation of High Speed Rotors Supported on Novel Internally Skewed Journal Bearings in a 60000 RPM Test Rig". En ASME Turbo Expo 2024: Turbomachinery Technical Conference and Exposition. American Society of Mechanical Engineers, 2024. http://dx.doi.org/10.1115/gt2024-123497.
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Abstract This paper presents the experimental and analytical stability investigation of high speed rotors supported on novel internally skewed journal bearings in a 60000 RPM test rig. The stability of turbocharger rotors has been widely investigated. Some expensive solutions for the stability of turbocharger rotors have been proposed, however this paper provides a simple bearing design with a skewed journal bearing that can be easily and simply applied to turbocharger rotors. In this paper the analytical model of the skewed journal bearings is first developed. Then the numerical analysis and the experimental stability results are provided for a 60000 rpm turbocharger test rig with a simple journal bearing, a floating ring bearing, and a skewed journal bearing. The skewed journal bearing showed superior stability characteristics both numerically and experimentally. In fact the test rig was stable with the skewed journal bearing up to the maximum speed of the test rig of 60000 rpm. The shaft centerline position in the bearings is also presented, as well as the power loss in the skewed journal bearings, thus providing a complete analysis of these internally skewed journal bearings. Design considerations are also discussed at the end of the paper.
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Walker, Alastair, Jayden Chee y Peter Roberts. "Developments in Testing and Manufacture of Thick-Walled Pipe". En ASME 2017 36th International Conference on Ocean, Offshore and Arctic Engineering. American Society of Mechanical Engineers, 2017. http://dx.doi.org/10.1115/omae2017-61083.
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Over the past 20 years there has been a considerable development of the capability to design and manufacture thick walled pipe to manufacture pipelines to operate in ultra-deep water. Design guidance is available in DNV OS F101 [1] in which the safety from pressure collapse failure during pipeline installation is determined by the use of a safety factor. The safety factor has been calibrated using the Load and Resistance Factor Design (LRFD) method in comparison with collapse pressure test results available at the time of preparation of DNV guidance. Because of the huge financial implications of loss of a very long pipeline during installation in ultra-deep water it has been the practice further to base the design of such a pipeline on specific pipe joint collapse tests in conjunction with the DNV information. Pressure testing full-scale pipe joints is an expensive undertaking that requires a suitable pressure chamber. Only a few chambers capable of applying pressures corresponding to very deep water are available in the world and transport of the pipes from the pipe mill to a suitable test facility may be very inconvenient and certainly expensive. This paper describes an alternative approach which could provide data that would enable the preparation of a safe approach specific to the pipeline diameter and design water depth. The approach could enable optimisation of the pipe design, particularly the pipe wall thickness. The proposed method is based on replacing costly full scale pipe tests by corresponding tests on ring specimens cut and machined from manufactured pipe joints. The proposal to use ring testing as the basis for design has been included successfully in the design of pipe for a recent ultra-deep water project [2]. The paper describes equipment used to subject the rings to external pressure and reports on tests carried out to validate the correspondence between the ring collapse pressure and that for the pipe joint from which the ring was obtained. Based on results from such tests it is concluded in this paper that ring pressure collapse testing is indeed a valid method to use as the basis for the design pipes in the next stage of ultra-deep water, i.e. increasing the capability to install pipeline in water depths down to 3500m from the current maximum level of 2500m.
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Veiga, José C., Carlos F. Cipolatti, Nelson Kavanagh, Fabio Castro y Valtemir Zandoná. "Serrated Metal Graphite Faced Gaskets for Ring Joint Flanges". En ASME 2012 Pressure Vessels and Piping Conference. American Society of Mechanical Engineers, 2012. http://dx.doi.org/10.1115/pvp2012-78349.
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Metal Ring Joint gaskets are used in piping and equipment that operate at high pressure and/or temperature. Flange faces for these gaskets are precisely machined and small imperfections on the sealing surface make them unusable, requiring replacement or expensive field machining. During plant shut-downs time constraints may not allow for flange replacement or surface repairs. As a temporary fix gasket manufacturers offer other gasket styles like graphite faced serrated metal or spiral wound. This paper studies the use of graphite faced serrated metal gaskets in ring joint flanges. In addition to laboratory tests, also the results of a successful application of a Double-Rail gasket in a shut-down of a Petrochemical plant are shown.
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Bouassida, H., N. Biboulet, P. Sainsot y A. A. Lubrecht. "Piston Ring Load Carrying Capacity: Influence of Cross-Hatching Parameters". En ASME/STLE 2012 International Joint Tribology Conference. American Society of Mechanical Engineers, 2012. http://dx.doi.org/10.1115/ijtc2012-61033.
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Energy and environment are of major concern in internal combustion engine component design. The piston ring-cylinder liner (PRCL) contact plays an essential part in design and is highlighted in this study. In fact, the rings ensure the sealing property, reducing the environmental impact by avoiding lubricant contamination (blow-by) and lubricant consumption. Unfortunately, when sealing, the rings generate between 11 to 24% of the friction losses in an internal combustion engine [1], thus reducing the energy efficiency of the engine. The cylinder liner surface features a special micro-geometry, a classical one is the cross-hatching pattern, obtained by honing. This texturing acts as a micro-bearing, oil reservoir and debris trap. Understanding the influence of texture parameters as groove depth and width or angle, will allow tribological improvements of the PRCL contact. The 2D transient Reynolds equation has to be solved for this kind of surface. The statistical method using the Patir and Cheng [2] flow factors is widely used. This approach lumps the different components of the surface (grooves and plateaux) and does not consider the roughness directionality. Methods decoupling both components, like the homogenization method [3] are also used. Another alternative is to use a deterministic model on measured surfaces, but this is a “hugely” expensive approach. Multigrid methods [4] are used to drastically reduce the calculational cost. The aim of the current study is to facilitate the understanding of measured surface calculations. Hence, analytical surfaces are used. They allow a flexible handling of the cross-hatching parameters. The plateaux are perfectly smooth and the grooves are sinusoidally shaped. The top ring is modelled using a parabolic profile. Periodic boundary conditions are used in the orthoradial direction and zero pressure conditions (Dirichlet) in the axial direction. To investigate the effect of different parameters, various imposed film thicknesses are applied and the mean load carrying capacity (LCC) over time is calculated. When representing the LCC corresponding to each parameter compared to the smooth LCC, as a function of the logarithm of the minimum film thickness, the curves are quite linear for small values of the film thickness and then for larger values they converge to 1.
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Gupta, Saurav y Grant M. Warner. "Power Harvesting for Rotating Structure Using Piezoelectric Generators". En ASME 2006 International Mechanical Engineering Congress and Exposition. ASMEDC, 2006. http://dx.doi.org/10.1115/imece2006-14842.
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Conventional method of measuring the mechanical properties of rotating machinery is to couple sensors on the machine through a slip ring, which is a non-trivial, expensive, lengthy and manpower intensive process. An alternative to this is to use a contactless RF slip ring which has no physical wear and hence no maintenance. But application of contactless RF slip ring is possible only if these services are low powered and sensor signals can be multiplexed. With the advance in low powered MEMS sensors, contactless slip ring system can be used. But providing power to these sensors is an issue. One approach would be to harness power from the untapped surrounding energy which could be used to recharge and/or replace battery powered connections. One method to accomplish this is to use piezoelectric materials (PZT) to capture energy lost due to vibration and rotation of the test equipment. This captured energy can then be used to provide uninterrupted power to the appropriate sensors. Focusing our attention on blades, rotating structures will be modeled as cantilever beam. Piezoelectric bimorph attached to the rotating cantilever beam will provide an estimate for the available power that can be used for harvesting.
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Tahmourpour, Farzad y Chris Warren Quinton. "Saving Expensive Offshore Deepwater Rig Time by Modeling Accurate Subsea/Subsea Floor Temperature Modeling for Cementing Operations". En SPE Annual Technical Conference and Exhibition. Society of Petroleum Engineers, 2009. http://dx.doi.org/10.2118/123738-ms.
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Smith, L. y L. Perras. "The Brimmond Reservoir Extending the Forties Field Into The Millennium By Maximising Profits Without Expensive Rig Upgrades". En SPE International Conference on Horizontal Well Technology. Society of Petroleum Engineers, 1998. http://dx.doi.org/10.2118/50383-ms.
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Yang, Limin y Torgeir Moan. "Cylinder Bore Wear Damage Analysis of a Heaving-Buoy Wave Energy Converter With Hydraulic Power Take-Off". En ASME 2010 29th International Conference on Ocean, Offshore and Arctic Engineering. ASMEDC, 2010. http://dx.doi.org/10.1115/omae2010-20164.
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Wave energy is a non-polluting and renewable source of energy. Among several wave energy converters (WEC), an oscillating body with a hydraulic power take-off (PTO) is commonly used for energy conversion. For such a hydraulic system, the piston ring and cylinder play very important roles in achieving desired energy converting performance and durability. Among the failure modes of the ring-bore components, wear is a prevailing one. Compared with the ring wear, cylinder wear is more important to the manufacturer and user, because cylinders are more expensive to replace than the rings. Since the floating body is exposed to irregular incident waves, the dynamic response of the PTO is also random. The position of maximum accumulated wear damage along the cylinder bore cannot be as easily determined as the engine bores where the maximum wear occurs near the Top Dead Centre (TDC). It is controlled by the characteristic dynamics of the system together with the lubrication of the interface which can be modelled by the well-known Stribeck curve. The purpose of this paper is to establish and apply a method for estimating the wear damage along the cylinder bore. The dynamic response of the WEC system is based on the nonlinear mathematical model established by Yang et al [1]. A particular issue in this research is to calculate the dimensionless film thickness λ (the ratio between the oil film thickness h and the composite surface roughness σ) in the lubricated contacts and then determine the lubrication regime according to the Stribeck curve. Combining the wear coefficient which is related to the lubrication regime and the contact pressure, the bore wear damage along the cylinder wall is predicted. In this paper, the bore wear damage is estimated on the basis of time domain simulations. The results show that the bore wear distribution is affected by two main factors: sea state condition and the nonlinearity of the PTO system. The position of the bore where the maximum accumulated wear occurs is predicted. Finally, the relative contribution of wear damage from different sea states is obtained.
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Reich, Alton y Roberto DiSalvo. "Analytical Method for Evaluating a 4-Piece Retaining Ring". En ASME 2022 Pressure Vessels & Piping Conference. American Society of Mechanical Engineers, 2022. http://dx.doi.org/10.1115/pvp2022-83675.
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Abstract Valves used for nuclear power applications are designed according to the rules in the ASME Section III Code [1]. A review of the applicable rules governing valve design (i.e. NC-3500) reveals that the Code favors valve body designs with very conventional shapes and elements. The nuclear supplier base has contracted over the past few decades and there are significantly fewer vendors that maintain nuclear QA programs than in the past. As a result, there has been an increasing trend toward using commercial grade dedication (CGD) methods to enable the use of valves successfully deployed in other applications for use as replacement parts, or as part of plant modifications, in nuclear power plants. This paper discusses the qualification of a check valve for a Section III application that had previously been used in other industries. The valve was designed with a split ring that retained the bonnet instead of a more traditional flanged cover. The split ring design is logical from a commercial perspective — it is faster to assemble and maintain the valve, and therefore less expensive to manufacture. However, the ASME Section III Code does not contemplate a split retaining ring in the standard design elements explicitly covered by the Code. This paper provides information about the split ring design and the analytical methods we developed to conservatively evaluate the as part of the valve pressure boundary.