Academic literature on the topic 'Fixed margins'
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Journal articles on the topic "Fixed margins"
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Jouvet, Guillaume, Jacques Rappaz, Ed Bueler, and Heinz Blatter. "Existence and stability of steady-state solutions of the shallow-ice-sheet equation by an energy-minimization approach." Journal of Glaciology 57, no. 202 (2011): 345–54. http://dx.doi.org/10.3189/002214311796405852.
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AbstractThe existence of solutions of the non-sliding shallow-ice-sheet equation on a flat horizontal bed with a mass balance linearly depending on altitude is proven for fixed margins. Free-margin solutions for the same mass balance do not exist. Fixed-margin solutions show unbounded shear stress and nonzero mass flux at the margin. Steady-state solutions with realistic margins, vanishing ice flux and vanishing shear stress are found numerically for ice sheets with Weertman-type sliding.
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Dilley, D. N., D. A. Stephenson, P. V. Bayly, and A. J. Schaut. "Frequency Shift in Drilling due to Margin Engagement." Journal of Manufacturing Science and Engineering 127, no. 2 (April 25, 2005): 271–76. http://dx.doi.org/10.1115/1.1863255.
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Drill chatter degrades hole roundness, hole size, and tool life. This wastes time and money in tools, scrap, and hole rework. Chatter prediction in milling and turning has shown significant benefit to industry; however, researchers have been unable to accurately predict chatter in drilling applications. In the past, the drill, including the chisel edge, was modeled as either a fixed-fixed or fixed-pinned beam (Tekinalp, O., and Ulsoy, A. G., 1989, “Modeling and Finite Element Analysis of Drill Bit Vibrations,” ASME J. Eng. Indust. 111, pp. 148–154), but more recent research (Dilley, D. N., Bayly, P. V., and Schaut, A. J., 2005, “Effects of the Chisel Edge on the Chatter Frequency in Drilling,” J. Sound Vib., 281, pp. 423–428) has shown that a fixed-embedded model using springs improves frequency matching. The effects of the drill margins on dynamics have not been studied. The fixed-fixed or fixed-pinned model will be shown to be inappropriate for modeling the effects of margin engagement, while the spring-end boundary condition can better approximate the frequency increase observed experimentally as the drill margins engage deeper into the hole. In addition, the shifted frequency is well below the frequency found from an analytical fixed-fixed or fixed-pinned beam. Evidence that the margins cause the frequency shift is seen in three-dimensional waterfall plots that show this shift for pilot hole drilling (in which the margins are engaged), but not for tube drilling (in which margins are not engaged).
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Lam, David, Yui Kaneko, Adam Scarlett, Basil D’Souza, Richard Norris, and Rodney Woods. "The Effect of Formalin Fixation on Resection Margins in Colorectal Cancer." International Journal of Surgical Pathology 27, no. 7 (June 14, 2019): 700–705. http://dx.doi.org/10.1177/1066896919854159.
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Resection margins in colorectal cancer carry clinical significance with regard to disease recurrence risk and selection for multimodal adjuvant therapy, especially with circumferential resection margins in rectal cancer. Colorectal cancer specimens are routinely fixed in formalin, which results in specimen and tumor-free margin shrinkage. However, the effects of shrinkage have not traditionally been taken into account when analyzing tumor-free margins. In this prospective study, 46 colorectal cancer specimens were measured in the fresh state and subsequently after formalin fixation for total specimen length, distal resection margin, and radial margin (circumferential resection margin for rectal cancer). The mean reduction after formalin fixation was 17.48 mm (14.7%) for distal resection margin and 1.20 mm (10.5%) for radial margin. For rectal cancer, circumferential resection margin reduction was 0.88 mm (11.8%); this was not affected by neoadjuvant chemoradiotherapy. Duration of formalin fixation did not significantly affect the extent of margin shrinkage. This is the first study to evaluate the effect of formalin fixation on radial resection margins, specifically as it relates to rectal cancer, and it demonstrates that shrinkage from formalin fixation should be a consideration in decision-making where the magnitude of tumor-free margins is small.
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Risselada, Marije, Kyle G. Mathews, and Emily Griffith. "Effect of feline skin specimen preparation on postexcision and postfixation tissue shrinkage." Journal of Feline Medicine and Surgery 18, no. 12 (July 10, 2016): 970–75. http://dx.doi.org/10.1177/1098612x15602951.
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Objectives This study was performed to assess skin–muscle–fascia specimen shrinkage and donor site changes, and to compare three techniques of specimen preparation for their effect on specimen shrinkage postexcision and after formalin fixation in feline cadaveric specimens. Methods Fifteen fresh feline cadavers were used for this study. Gelatin spheres were implanted in paired thoracic subcutaneous pockets and subsequently excised with 30 mm lateral margins and a fascial plane as the deep margin. Skin and fascia were either left unsutured, sutured together using four simple interrupted quadrant sutures (‘four-quadrant-sutured’) or sutured together in a continuous pattern (‘circumferentially sutured’). Specimens were measured for tumor-free margins on the excised and fixed specimens. The donor site defect was assessed for enlargement after specimen excision. Statistical analyses were performed to assess the donor site enlargement, and the influence of preparation technique on margin size, with significance set at P <0.05. Results The closest skin margins on the excised and fixed specimens were significantly smaller than the planned 30 mm margins; however, no significant difference was found between postexcision and postfixation specimens. No significant differences were found between the three techniques ( P = 0.74) with regard to margins either after excision or fixation. The fascial and skin defects of the donor site were significantly larger than the planned excision. Conclusions and relevance Surgically obtained feline skin–muscle–fascia specimens will significantly decrease in size prior to formalin fixation, resulting in falsely decreased measurements from tumor to tissue margins. Affixing the skin to the fascia does not significantly influence this decrease in margin size in feline tissue specimens at this location.
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Alalouf, I. S. "The Chi Square Test With Both Margins Fixed." Communications in Statistics - Theory and Methods 16, no. 1 (January 1987): 29–43. http://dx.doi.org/10.1080/03610928708829350.
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Rachmat, Radhi Abdul Halim, and Ii Halilah. "PENGARUH EFEKTIFITAS PENGELOLAAN MODAL KERJA DAN AKTIVA TETAP TERHADAP NET PROFIT MARGIN." Jurnal Riset Bisnis dan Investasi 1, no. 3 (January 26, 2016): 12. http://dx.doi.org/10.35697/jrbi.v1i3.51.
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Working capital and fixed assets is an important component in the internal aspects of a company, with an investment in working capital and fixed assets expected the company is able to obtain the maximum level of profitability. This study aims to determine the extent to which influence effectiveness of working capital and the effectiveness of fixed assets to Net Profit Margin. From the test results simultaneously using the F test, it can be concluded that the effectiveness of the management of working capital and fixed assets Net effect on profit margins. From the results of the partial testing using t test, for the dependent variable is the net profit margin then it can be concluded that the effectiveness of the management of working capital is not partial effect on the profit margin ratio and effectiveness of the management of fixed assets partial effect on the profit margin ratio.
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Hertig, Paul. "The Multi-ethnic Journeys of Jesus in Matthew: Margin-Center Dynamics." Missiology: An International Review 26, no. 1 (January 1998): 23–35. http://dx.doi.org/10.1177/009182969802600103.
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Matthew paints geographical portraits of marginality through the continuous journeys of Jesus, the migrant God. Galilee of the Gentiles, a crossroads of cultures and empires, served as the appropriate mission base for Jesus' center-margin journeys. Matthew paints social portraits of marginality through Jesus' encounters with individuals such as the centurion, the Canaanite woman, and the Galilean women who follow Jesus to the cross and the tomb. This study redefines marginality as a continuous journey to and from margins and centers, thus departing from the traditional definition of static in-betweenness. The church today is neither a fixed center nor a margin, but discovers its identity through its journeys on the way to and from multiple margins and centers.
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D’Addona, Stefano, and Lilia Cavallari. "External Shocks, Trade Margins, and Macroeconomic Dynamics." Economies 8, no. 1 (January 14, 2020): 6. http://dx.doi.org/10.3390/economies8010006.
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This paper studies the role of the exchange rate regime for trade of new products. It first provides VAR evidence that a rise in external productivity shifts trade away from new products and more so in fixed regimes. Then, it presents a model with firm dynamics in line with this evidence. We argue that exchange rate policy can affect firms’ entry decisions with consequences for the competitiveness of a country’s exports well beyond the short run. In our setup, fixed exchange rates can foster the competitiveness of firms that trade new products, while flexible rates favor firms that produce mature products.
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Kell, M. R., C. Dunne, C. Canning, and M. Morrow. "The effect of margin status on local recurrence following breast conservation and radiation therapy for DCIS." Journal of Clinical Oncology 25, no. 18_suppl (June 20, 2007): 597. http://dx.doi.org/10.1200/jco.2007.25.18_suppl.597.
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597 Background: There is no consensus on what constitutes an adequate surgical margin in patients receiving breast conserving surgery (BCS) and postoperative irradiation (RT) for ductal carcinoma in situ (DCIS). Inadequate margins may result in high local recurrence, and excessively large resections may lead to poor cosmetic outcome without oncological benefit. Methods: A comprehensive search for published trials which examined outcomes after adjuvant RT following BCS for DCIS was performed using medline and cross referencing available data. Reviews of each study were conducted, and data were extracted. Fixed and random effects methods were used to combine data. Primary outcomes were in breast tumour recurrence (IBTR) related to surgical margins. Results: Analysis of 3,606 patients from randomized trials confirms that patients with negative margins are significantly less likely to recur than those with positive margins after RT (RR 0.53, 95% CI= 0.42 to 0.66, p<0.01). Combined data from randomized and non randomized trials, of 5,500 patients, demonstrates that where the margin status is close or unknown there is significant risk of IBTR compared to a negative margin (RR=1.68, 95% CI= 1.22–2.33, p<0.01). When specific margin thresholds are examined a 2 mm margin is superior to less than 2 mm (OR=0.67, 95% CI 0.51 -0.89, p<0.01), however we saw no significant difference in the rate of IBTR between a 2 mm margin and >5 mm (OR=1.49, 95% CI 0.54 to 4.9, p>0.05). Conclusions: Surgical margins negative for DCIS should be obtained following BCS for DCIS. A margin threshold of 2mm appears be as good as a larger margin when BCS for DCIS is combined with RT. No significant financial relationships to disclose.
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Ohn, Sung Min, Hwa Chang Song, and Byong Hoon Jang. "Parameter Determination for Back-to-Back Converters in Power Systems to Enhance Interface Flow Margins." Advanced Materials Research 433-440 (January 2012): 3964–68. http://dx.doi.org/10.4028/www.scientific.net/amr.433-440.3964.
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This paper presents a method to determine parameters of BTB (back-to-back) converters in terms of the enhancement of interface flow margins. Interface flow margin is by definition a measure of how much active power can be transferred from the external areas to the study area with the fixed load demand, and it is mainly constrained by system voltage stability. BTB converters are controllable equipments with the active power flow through them, and its DC link in fact can divide the AC systems at the location and hence can reduce the fault current level. This paper first calculates margin enhancement sensitivities at the nose point of F-V curves and formulates an optimization problem to update the BTB parameters to improve the margins. This procedure is repeated performed until the required margin enhancement is achieved.
Dissertations / Theses on the topic "Fixed margins"
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Hendrickson, Gretchen. "Stability of rater agreement measures the effect of shifting cell values within fixed margins /." Diss., Columbia, Mo. : University of Missouri-Columbia, 2007. http://hdl.handle.net/10355/6275.
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Thesis (M.A.)--University of Missouri-Columbia, 2007.The entire dissertation/thesis text is included in the research.pdf file; the official abstract appears in the short.pdf file (which also appears in the research.pdf); a non-technical general description, or public abstract, appears in the public.pdf file. Title from title screen of research.pdf file (viewed on May 28, 2009) Includes bibliographical references.
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Mirshawka, Valéria Zimpeck. "Preços de transferência: diferentes visões." Universidade de São Paulo, 2012. http://www.teses.usp.br/teses/disponiveis/2/2133/tde-22042013-093407/.
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O presente estudo tem por objetivo avaliar o regime brasileiro de controle dos preços de transferência sob o enfoque das diferentes visões que o tema pode apresentar. Inicialmente são relatadas suas principais características como a questão do arms length principle, seu histórico e aplicação, para em seguida falar-se acerca da disciplina no âmbito da OCDE e no direito comparado. Na sequência é abordada a legislação brasileira sobre o tema, a posição da jurisprudência, seu confronto com a valoração aduaneira, bem como sua relação com os acordos para se evitar a dupla tributação. Após configurado este cenário de introdução do estudo e seus principais contornos, são efetivamente analisadas as diferentes visões que o tema pode apresentar, notadamente em relação à recepção do arms length, a adoção de margens fixas e a questão da superioridade hierarquica dos tratados para se evitar a dupla tributação e a lei interna, no caso a lei dos preços de transferênciaThis study examines the Brazilian Transfer Pricing Regime from the standpoint of the different views that the issue may have. Initially the main characteristics are reported, for example, the arm\'s length principle, its history and application, thereafter it advocates the discipline within the OECD and comparative law. Following is addressed the Brazilian Transfer Pricing legislation, the position of jurisprudence facing with the customs valuation, and their relation with the double tax treaty. Once set up this introduction study scenario and its main outlines, are effectively analyzed the different views that the subject may have, especially with respect to the receipt of the arm\'s length principle, the adoption of fixed margins and the issue of hierarchical superiority of double tax treaties and domestic law, in case, transfer pricings law.
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Al, Habbaki Patricia. "Les incidences des politiques de commerce extérieur et de change sur les échanges commerciaux des pays du Mashrek (Liban, Syrie Jordanie et Egypte)." Thesis, Tours, 2014. http://www.theses.fr/2014TOUR1007/document.
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En dépit du renforcement de leur ouverture commerciale, le commerce extérieur des pays du Mashrek a presque toujours affiché des chiffres plutôt négatifs. Selon la littérature, l'ouverture commerciale est une des conditions permettant une croissance vigoureuse d'un pays. Néanmoins, la tendance constatée à la lumière des données du commerce de ces pays, traduirait une réalité alarmante. L'ouverture ne s'est pas traduite par une accélération des niveaux des investissements, ni par une création d'emplois. Est-ce que les politiques commerciales et de change menées par les pays du Mashrek sont responsables de cette persistance des déficits commerciaux ? Motivée par l’aggravation remarquable du solde de la balance commerciale libanaise survenue dans le profil global des échanges extérieurs du Liban, la présente recherche examine le comportement dynamique des exportations et importations libanaises en comparaison avec ses pays voisins (la Syrie, l’Egypte et la Jordanie) dans un contexte économique régional et international en mutation, en proposant une analyse empirique des déterminants des flux commerciaux ayant pour objet d’établir dans quelle mesure la politique commerciale et de change seraient responsables des faits stylisés observésDespite the strengthening of their commercial openness, the Mashreq countries trade has rather always displayed negative results. According to the literature, opening up trade is one of the conditions leading to any country’s vigorous growth. Nevertheless, the trend found in the light of these countries’ trade data, indicates an alarming reality. The openness was neither translated into accelerated levels of investments nor created new job opportunities. Are the trade and exchange rate policies pursued by the Mashreq countries responsible for this persistence in trade deficits ? Motivated by outstanding worsening deflection of the trade balance in the overall Lebanese external trade profile, the current research examines the dynamic behavior of the Lebanese exports and imports compared to its neighboring countries (Syria, Egypt, and Jordan) in a regional and international changing economic context. An empirical analysis of the trade flows determinants was adopted in order to establish to what extent the trade and Exchange policies would be responsible for the observed stylized facts
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Briglauer, Wolfgang, Georg Götz, and Anton Schwarz. "Margin Squeeze in Fixed-Network Telephony Markets - competitive or anticompetitive?" Forschungsinstitut für Regulierungsökonomie, WU Vienna University of Economics and Business, 2010. http://epub.wu.ac.at/3070/1/wp13.pdf.
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This paper looks at the effects of different forms of wholesale and retail regulation on retail competition in fixed network telephony markets. We explicitly model two asymmetries between the incumbent operator and two entrants: (i) While the incumbent has zero marginal costs, the entrant has the wholesale access charge as (positive) marginal costs; (ii) While the incumbent is setting a two-part tariff at the retail level (fixed fee and calls price), the entrant can only set a linear price for calls. We model the product of the incumbent as horizontally differentiated from the products of the entrants who are homogenous and do not have any market power. Competition from other infrastructures such as mobile telephony or cable is modelled as an "outside opportunity" for consumers. We find that entrants without market power might be subject to a margin squeeze if the wholesale access price is set at average costs and competitive pressure from other infrastructures increases. Product differentiation, however, prevents market foreclosure. We argue that a wholesale price regulation at average costs is not optimal in such a situation and discuss retail-minus and deregulation as potential alternatives. (author's abstract)Series: Working Papers / Research Institute for Regulatory Economics
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Fridell, Anna, and Hanna Josefsson. "The influence of seating load on internal and marginal fit of a fixed dental prosthesis." Thesis, Malmö högskola, Odontologiska fakulteten (OD), 2015. http://urn.kb.se/resolve?urn=urn:nbn:se:mau:diva-19974.
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Syfte: Syftet med studien var att undersöka hur olika axiala tryck och skjuvkrafter påverkade marginal och intern passform i en sexledsbro i titan i överkäkens frontregion.Material och metod: En litteratursökning gjordes för att insamla bakgrundsmaterial. Stödtänderna 13 12 11 21 22 23 preparerades på en plastmodell för en sexledsbro och en anatomiskt utformad bro i titan framställdes med hjälp CAD/CAM. En mastermodell av stödtänderna tillverkades i epoxyresin. Genom att använda replikateknik utvärderades brons passform vid olika cementeringstryck; 20, 35, 50, 70 N och 50 N med skjuvkrafter. Varje replika snittades med hjälp av en ”jig” och cementspalten analyserades i ett mikroskop. All data granskades statistiskt.Resultat: Resultatet visade att ett tryck med 20 N generellt gav en ej acceptabel passform och ett tryck med 35 N hade en stor spridning. Vid tryck med 50 N kunde mindre cementspalter ses. De blev inte mindre vid test med 70 N. När skjuvkrafter adderades försämrades resultaten jämfört med försöken med 50 N och 70 N.Konklusion: Ett tryck vid cementering som överstiger 50 N förbättrar ej passformen markant. Närvaro av skjuvkrafter påverkar passformen negativt. Ett lägre tryck på 20 N ger dock en mindre fördelaktig passform jämfört med skjuvkrafter förutsatt att ett tillräckligt högt tryck används. Alla slutsatser var statistiskt signifikanta.Purpose: The purpose of this study is to investigate how different axial seating loads and shear loads influences the marginal and internal fit of a titanium six unit FDP in the upper jaw frontal region.Materials and Methods: A literature search was made to acquire background material. Preparations of abutment teeth for a six unit FDP 13 12 11 21 22 23 were made on plastic teeth, and an anatomically designed titanium FDP was constructed using CAD/CAM. A master cast of the abutment teeth was fabricated in epoxy resin. Using the impression replica technique the fit of the FDP was evaluated by different seating loads during cementation; 20, 35, 50, 70 N and 50 N under the presence of shear loads. The replicas were sectioned using a jig and the cement gap was analysed using a microscope. All the data were statistically analysed.Results: The results showed that a seating load of 20 N generally gave an unacceptable fit and that the seating load of 35 N had great range. At seating loads of 50 N less cement gaps could be seen, i.e. more favourable fit. These results did not improve when testing with 70 N. With a presence of shear loads the results were poorer than when testing with 50 and 70 N.Conclusions: A seating load exceeding 50 N during cementation does not markedly give a more favourable fit. The presence of shear loads affects the fit negatively. A lower seating load of 20 N gives a less favourable fit compared to shear loads provided that a seating load high enough is used. All of these conclusions were statistically significant.
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Almustafa, Nawaf Mohammed. "The use of CAD CAM for fixed partial prostheses." Thesis, University of Dundee, 2016. https://discovery.dundee.ac.uk/en/studentTheses/7185f4c0-4f47-4072-8b0a-7ae09c1e8c01.
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Due to the increasing demand from patients and dentists for highly aesthetic and strong, metal-free restorations there has been a rapid increase in research into dental CAD CAM technique and zirconia based restorations over the last decade. Such new technology has the potential to take the place of conventional techniques and materials for fabricating indirect dental restorations in the future. In this PhD thesis, five laboratory studies were designed to investigate zirconia bridges constructed using dental CAD CAM. The studies concentrated on: 1. Ideal force applied by dentists for cementing zirconia bridges and the impact on seating. 2. The effect of firing cycles and zirconia thickness on the fit of zirconia bridges. 3. The effect of span length on the fit of three and four unit all zirconia bridges. 4. The effect of veneering on the strength of three unit zirconia bridges. 5. The fit of three unit all zirconia bridges produced by digital and conventional techniques. For these laboratory studies an ideal three unit (and four unit for study 3) fixed-fixed all ceramic bridge preparation was carried out on two plastic teeth and all SLA models and zirconia based bridges were made using the Lava COS and Lava™ CAD CAM system (3M, ESPE). In addition to the laboratory studies, a clinical audit was carried out to assess satisfaction (dentist, dental technician and patient) with zirconia based restorations (through a xvi series of questionnaires) made and fitted at Dundee Dental Hospital and School. In addition, as part of this audit a simple cost analysis was carried out to explore the differences in cost between zirconia based restorations and high fusing gold alloy based metal ceramic restorations. Four of the studies (studies 1, 2, 3 and 5) investigated the internal and marginal fit of the zirconia based restorations under differing laboratory and clinical procedures and conditions. It was found that the seating force used to cement a zirconia based bridge had no impact upon fit (Study 1). Whilst the thickness of zirconia (all-zirconia bridge and un-veneered zirconia framework) did not affect the fit of the restoration, veneering the framework did lead to a statistically significant deterioration in fit (Study 2). Although leading to a poorer fit veneering did have a positive effect in strengthening the zirconia framework, but neither un-veneered nor veneered frameworks were as strong as monolithic/all zirconia bridges (Study 4). Despite the high shrinkage during post milling sintering and the potential for greater distortion on longer span bridges, the longer span bridges investigated in Study 3 did not impact upon fit. In study 1, 2, 3 and 4 the Lava COS intra-oral scanner was used to create a digital impression of the tooth preparations and study 5 confirmed that the fit of bridges made from these impressions were better than those made using conventional addition cured silicone putty and wash impressions (Study 5). The results of the questionnaires used in the audit revealed high satisfaction rates with all stake holders and the cost analysis showed that producing zirconia based restorations can be five to six times cheaper than conventional gold based restorations. Despite the variations in fit which were found in Studies 2 and 5, all bridges produced were within what would be regarded as clinically acceptable and comparable to those produced with more traditional techniques.
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Pinto, Tatiana Saretta Ferreira. "Avaliação da adaptação marginal de copings cerâmicos obtidos por diferentes métodos de moldagem /." São José dos Campos, 2018. http://hdl.handle.net/11449/157331.
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Orientador: Rodrigo Máximo de AraújoBanca: Vinícius Anéas Rodrigues
Banca : Eduardo Galera da Silva
Resumo: O objetivo desse estudo foi avaliar a adaptação marginal de copings cerâmicos obtidos pelos métodos de moldagem convencional e escaneamento. Os modelos foram separados em 3 grupos para avaliação e todas as coroas foram confeccionadas sobre um modelo mestre previamente fabricado em CoCr. Grupo 1: Com o auxílio de uma moldeira individual cilíndrica de acrílico foram reproduzidas 10 moldagens com silicona de adição (Panasil) no modelo mestre pela técnica de moldagem dupla e replicados dez modelos físicos em gesso pedra Fuji Rock.Sobre esses modelos foi realizado o enceramento dos copings, confecção dos sprues de cera e sobre eles foi realizada a injeção da cerâmica Grupo 2: foram realizadas 10 moldagens diretas com scanner extraoral (Swing Dental Scanner) no modelo mestre. As imagens foram obtidas através do software Exocad e copings em IPS-Emax CAD foram confeccionados em fresadora (Ceramill Motion 2) para posterior sinterização da cerâmica. Grupo 3: foram realizadas 10 moldagens diretas com scanner intraoral (CEREC Bluecam) no modelo mestre. As imagens foram obtidas através do software Exocad. Copings em IPS-Emax CAD foram confeccionados em fresadora (Ceramill Motion 2) para posterior sinterização da cerâmica. Os copings de cerâmica não foram cimentados no modelo mestre, apenas posicionados e mantidos com pressão constante de 1,4 a 1,5 kg durante a medição, com a ajuda de um delineador adaptado para esse trabalho, onde oito pontos eletivos foram usados como referência para med... (Resumo completo, clicar acesso eletrônico abaixo)
The objective of the study was to evaluate the marginal adaptation of ceramic crowns obtained by conventional molding and scanning methods. The models were separated into 3 groups for evaluation and all the crowns were made on a master model previously manufactured in CoCr. For group 1: With the aid of a single cylindrical acrylic tray the master model was molded 10 times with Panasil in the master model by the technique of double molding and replicated ten physical models in stone gypsum Fuji Rock. On these models was done the waxing of the copings, making the sprues of wax and on them was carried out the injection of the ceramics In group 2, 10 direct impressions were performed with the Swing Dental Scanner (Korea) extra oral scanner in the master model. The images were obtained through the software Exocad (GmbH) and copings in IPS-Emax CAD were made in the Ceramill Motion 2 (Amanngirrbach) mill for subsequent sintering of the ceramics. In group 3, 10 direct impressions were performed with the CEREC Bluecam intraoral scanner (Sirona Dental Systems) in the master model. The images were obtained through the Exocad (GmbH) software. IPS-Emax CAD copings were made in the Ceramill Motion 2 (Amanngirrbach) mill for subsequent sintering of the ceramic. Ceramic copings were not cemented in the master model, only positioned and maintained with a constant pressure of 1.4 to 1.5 kg during the measurement, with the aid of an eyeliner adapted for this work, where eight elective points were used as reference to measure the vertical distance between the end line of the master model and the end line of the copings. The margin at each point was measured 3 times with stereo microscope Discovery V20 (ZEISS). The mean was calculated and submitted to the ANOVA variance test "with a significance level of 5% and the following results were obtained: 66.15μm for group 1; 67.48μm for group ...(Resumo completo, clicar acesso eletrônico abaixo)
Mestre
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Fragoso, Wagner Sotero. "Adaptação marginal de infra-estruturas implanto-retidas obtidas por tecnica de fundição-sobre-analogos." [s.n.], 2005. http://repositorio.unicamp.br/jspui/handle/REPOSIP/289194.
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Orientador: Guilherme Elias Pessanha HenriquesDissertação (mestrado) - Universidade Estadual de Campinas, Faculdade de Odontologia de Piracicaba
Made available in DSpace on 2018-08-04T03:50:42Z (GMT). No. of bitstreams: 1 Fragoso_WagnerSotero_M.pdf: 846623 bytes, checksum: 8a6eb47d9e498f7baef57b0a8a9006b6 (MD5) Previous issue date: 2005
Resumo: A redução de desajustes marginais em estruturas suportadas por implantes osseointegrados é requerida para maior longevidade das fixações. Este trabalho teve o propósito de avaliar o desajuste marginal de infra-estruturas metálicas implanto-retidas fundidas em titânio comercialmente puro (Ti c.p.) pela técnica de fundição-sobre-análogos, comparando os resultados com estruturas obtidas pela incorporação de cilindros cimentados e pela técnica convencional de fundição tipo monobloco. A partir de uma matriz metálica mandibular contendo 05 análogos de abutments tipo Micro Unit, 10 estruturas foram obtidas de modelos elaborados em revestimento pela fundição-sobre-análogos. Estruturas com cilindros incorporados mediante cimentação por agente resinoso e pela técnica convencional em monobloco, foram manufaturadas de outros 20 modelos elaborados em gesso. As leituras de desajuste foram conduzidas num microscópio mensurador com aumento de 120X, tendo sido baseadas no protocolo do aperto de 10 Ncm em um único parafuso distalmente posicionado e avaliação de desajuste no segmento em alça. Pelo Análise de Variância e teste de Tukey foram constatadas diferenças estatísticas significativas (P=0,01) entre os valores médios do grupo cilindro cimentado (27,90±6,61µm), monobloco (332,87±63,91µm) e fundição-sobre-análogos (97,70±40,53µm). As estruturas metálicas implanto-retidas obtidas pela técnica de fundição-sobre-análogos apresentaram melhor adaptação marginal que as fundidas em monobloco, mas com maior desajuste que as estruturas com cilindros cimentados
Abstract: The reduction of marginal gap in osseointegrated implant-supported frameworks is required for longevity of the settings. The purpose of this study was to evaluate the marginal misfit of cast implant-retained frameworks made from commercially pure titanium (CP Ti) comparing: the over-analog casting technique, cemented cylinders technique, and the conventional one-piece casting technique. From a mandibular master cast containing 05 Micro Unit abutment analogs, 10 frameworks were made from investment material for over-analog casting technique. Twenty dental stone casts were used for both cemented cylinder and one-piece casting techniques. A resinous agent was used for the cemented cylinders technique. The marginal gaps were measured using a traveling microscope (×120) by means of single-screw test protocol: tightness of 10 Ncm of distal screw and evaluation of marginal gap in the opposed extension. Mean marginal misfit data were calculated for each framework. Analysis of Variance and Tukey test exhibited statistical significant differences (P=0.01) among the misfit mean values of the cemented cylinders group (27.90±6.61µm), one-piece casting group (332.87±63.91µm) and over-analog casting group (97.70±40.53µm). The over-analog casting technique provided a smaller marginal misfit than one-piece casting technique, however the over-analog casting technique resulted in a higher marginal gap than cemented cylinders technique
Mestrado
Protese Dental
Mestre em Clínica Odontológica
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Lopes, Leonardo Ferreira de Toledo Piza. "Avaliação da precisão de aquisição de dados nos Sistemas CAD/CAM : desadaptação marginal horizontal /." Araçatuba, 2015. http://hdl.handle.net/11449/123982.
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Orientador: Eduardo Piza PellizzerCoorientador: José Vitor Quinelli Mazaro
Banca: Fellippo Ramos Verri
Banca: Sandra Lúcia Dantas de Moraes
Resumo: Objetivo: O objetivo deste estudo foi avaliar a adaptação marginal horizontal de infraestruturas de próteses fixas confeccionadas pelo sistema CAD-CAM com três diferentes sistemas de aquisição de dados. Material e Métodos: Foram confeccionados 50 corpos de prova divididos em 5 grupos, sendo eles, Convencional (Ni-Cr); GI: iTero; GII: CerecBluecam/fresadora industrial; GIII: 3S; GIV: CerecBluecam/ fresadora Sirona, todos com n=10. Os corpos de prova foram numerados e randomizados, realizou-se análise da desadaptação marginal horizontal, esta dividida em positiva para sobre-contorno e negativa para subcontorno. Resultados: A análise intra-examinador revelou não haver diferença estatística entre os dois períodos de análise (t pareado=0.019; p=0.985). Em relação as desadaptações de sobre-contorno (valores positivos) podemos analisar que o grupo controle (Convencional) apresentou estatisticamente (p <0.001) menores valores de desadaptação (82 μm) quando comparado com o grupo CAD/CAM (144 μm). Ao comparar o sistema intra/extra-oral pode-se observar que o grupo intra-oral (iTero) apresentou melhores resultados, sendo essa diferença estatisticamente significante (p <0.001) que o extra-oral (3s). Já avaliando a diferença entre um sistema aberto com um fechado foi observado que o sistema aberto apresentou estatisticamente menor desadaptação (p<0.001). Quando avaliou-se a "quebra" de um sistema fechado (Cerec BlueCam) para sua fresagem a nível industrial notou-se que há desvantagens em tal procedimento, pois houve estatisticamente maiores desadaptações no grupo da "quebra" do sistema (p<0.001). Em contra partida nenhuma diferença estatisticamente significante foi encontrada em todas as análises quando se comparou desadaptação por sub contorno. Significância: Avaliando a discrepância...
Abstract: Objective: The aim of this study was to evaluate the horizontal marginal fit of frameworks produced by CAD/CAM systems with 3 different data acquisition. Material and Methods: We fabricated 50 frameworks divided into 5 groups, Conventional (Ni- Cr); GI: iTero; GII: CerecBluecam/industrial milling; GIII: 3S; GIV: CerecBluecam/Sirona, all with n = 10. We numbered the specimens and analyzed them randomly. Results: Intra-observer analisys indicated no statistically significant difference (paired t-test=0.019; p=0.985). In relation to the overextended horizontal marginal discrepancy (Positive Values) can analyze that the Control group (Conventional) had significantly (p < 0.001) minor discrepancy values (82 μm) when compared to the CAD / CAM group (144 μm). When comparing the systems intra/extra oral can be appreciated that the intra oral group (Itero) presented statistically best results when comparing(p < 0.001) that the extra oral ( 3s ). Evaluating the difference between the open system with closed was observed that the open system had statistically smaller misfit (p < 0.001). Evaluating the "broke" of a closed system (Cerec Bluecam) your industrial milling had statistically (p < 0.001) worse adaptation when compared to the laboratorial milling. About the under extended marginal discrepancy, in all analysis there was not found statistically significant difference. Significance: Assessing the horizontal marginal discrepancy was possible to note that in relation to the overextended the control group had statistically better results than the CAD/CAM systems, however the Cerec Bluecam system by sirona milling had better results than all CAD/CAM system and also the control group. There was no difference between the under extended misfit and all analysis
Mestre
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Lopes, Leonardo Ferreira de Toledo Piza [UNESP]. "Avaliação da precisão de aquisição de dados nos Sistemas CAD/CAM: desadaptação marginal horizontal." Universidade Estadual Paulista (UNESP), 2015. http://hdl.handle.net/11449/123982.
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000831388.pdf: 562171 bytes, checksum: e080c07a229e0894fa23757920f53d4c (MD5)Objetivo: O objetivo deste estudo foi avaliar a adaptação marginal horizontal de infraestruturas de próteses fixas confeccionadas pelo sistema CAD-CAM com três diferentes sistemas de aquisição de dados. Material e Métodos: Foram confeccionados 50 corpos de prova divididos em 5 grupos, sendo eles, Convencional (Ni-Cr); GI: iTero; GII: CerecBluecam/fresadora industrial; GIII: 3S; GIV: CerecBluecam/ fresadora Sirona, todos com n=10. Os corpos de prova foram numerados e randomizados, realizou-se análise da desadaptação marginal horizontal, esta dividida em positiva para sobre-contorno e negativa para subcontorno. Resultados: A análise intra-examinador revelou não haver diferença estatística entre os dois períodos de análise (t pareado=0.019; p=0.985). Em relação as desadaptações de sobre-contorno (valores positivos) podemos analisar que o grupo controle (Convencional) apresentou estatisticamente (p <0.001) menores valores de desadaptação (82 μm) quando comparado com o grupo CAD/CAM (144 μm). Ao comparar o sistema intra/extra-oral pode-se observar que o grupo intra-oral (iTero) apresentou melhores resultados, sendo essa diferença estatisticamente significante (p <0.001) que o extra-oral (3s). Já avaliando a diferença entre um sistema aberto com um fechado foi observado que o sistema aberto apresentou estatisticamente menor desadaptação (p<0.001). Quando avaliou-se a quebra de um sistema fechado (Cerec BlueCam) para sua fresagem a nível industrial notou-se que há desvantagens em tal procedimento, pois houve estatisticamente maiores desadaptações no grupo da quebra do sistema (p<0.001). Em contra partida nenhuma diferença estatisticamente significante foi encontrada em todas as análises quando se comparou desadaptação por sub contorno. Significância: Avaliando a discrepância...
Objective: The aim of this study was to evaluate the horizontal marginal fit of frameworks produced by CAD/CAM systems with 3 different data acquisition. Material and Methods: We fabricated 50 frameworks divided into 5 groups, Conventional (Ni- Cr); GI: iTero; GII: CerecBluecam/industrial milling; GIII: 3S; GIV: CerecBluecam/Sirona, all with n = 10. We numbered the specimens and analyzed them randomly. Results: Intra-observer analisys indicated no statistically significant difference (paired t-test=0.019; p=0.985). In relation to the overextended horizontal marginal discrepancy (Positive Values) can analyze that the Control group (Conventional) had significantly (p < 0.001) minor discrepancy values (82 μm) when compared to the CAD / CAM group (144 μm). When comparing the systems intra/extra oral can be appreciated that the intra oral group (Itero) presented statistically best results when comparing(p < 0.001) that the extra oral ( 3s ). Evaluating the difference between the open system with closed was observed that the open system had statistically smaller misfit (p < 0.001). Evaluating the broke of a closed system (Cerec Bluecam) your industrial milling had statistically (p < 0.001) worse adaptation when compared to the laboratorial milling. About the under extended marginal discrepancy, in all analysis there was not found statistically significant difference. Significance: Assessing the horizontal marginal discrepancy was possible to note that in relation to the overextended the control group had statistically better results than the CAD/CAM systems, however the Cerec Bluecam system by sirona milling had better results than all CAD/CAM system and also the control group. There was no difference between the under extended misfit and all analysis
Books on the topic "Fixed margins"
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Caballero, Ricardo J. Fixed costs: The demise of marginal q. Cambridge, MA: National Bureau of Economic Research, 1996.
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Caballero, Ricardo J. Fixed costs: The demise of marginal q. Cambridge, Mass: Dept. of Economics, Massachusetts Institute of Technology, 1996.
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1948-, Rüschendorf Ludger, Schweizer B, and Taylor Michael D. 1940-, eds. Distributions with fixed marginals and related topics. Hayward, Calif: Institute of Mathematical Statistics, 1996.
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Popenhagen, Ron J. Modernist Disguise. Edinburgh University Press, 2021. http://dx.doi.org/10.3366/edinburgh/9781474470056.001.0001.
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This book chronicles and theorises face and body masking in arts and culture from the mid-nineteenth century to the new millennium. While featuring the modernist era in France, analyses include commentary on performers and visual artists from the margins of the European continent: Ireland and the Baltics; Denmark and the Mediterranean. Representations of silent Pierrots on stage are contrasted with images of fixed-form maskers and masquerades; two-dimensional depictions in paintings and photographs further the study of the form-altered human figure. The relationship of the European avant-garde with indigenous masquerade from Africa and the Americas is discussed and presented in a series of eighteen photographic counterpoints. Modernist explorations of the masked gaze and the nature of looking with the painted face are considered. Meanings suggested by the disguised body in motion and in stasis are investigated via citations of the work of a wide range of masqueraders: Akarova, Bernhardt, Cahun, Höch, Fuller, Mnouchkine, Stein and Wigman, as well as Artaud, Barrault, Cocteau, Copeau, Deburau, Fo, Milhaud and Picasso. Connections between modernist disguising with manifestations of masquerade in daily life, fashion, fine art, media, opera and theatre are proposed while arguing that masking and the carnivalesque are omnipresent in contemporary culture. Modernist Disguise provides greater understanding of the impact of facial masking upon everyday interactions and perceptions experienced, for instance, during the ongoing COVID-19 pandemic. The book proposes an interdisciplinary and international lexicon for critical conversation on masking objects, mask play and masquerade as performance.
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Holmes, Craig. The Individual Benefits of Investing in Skills. Edited by John Buchanan, David Finegold, Ken Mayhew, and Chris Warhurst. Oxford University Press, 2017. http://dx.doi.org/10.1093/oxfordhb/9780199655366.013.17.
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This chapter considers returns to the individual from investing in skill. It describes the earnings and employment outcomes of people who have completed different levels of formal education across different countries, and goes on to consider the possible causal mechanisms at work. The methodology for estimating wage returns is critically discussed. Whilst much attention has been devoted to considering ability bias, other issues have received less attention. In particular qualifications or amounts of time spent studying are imperfect proxies for skills produced. Furthermore estimates from wage regressions are almost invariably interpreted through the lens of human capital theory -- the existence of a wage premium indicates that the productivity has increased due to the educational investment. Alternative interpretations are considered. These include the possibility that the premium represents a reward for obtaining a job on a fixed distribution of jobs -- in other words winning a positional competition race. Such possibilities raise several concerns. These include under-utilisation, both of general skills and of skills acquired through work-based training programmes, low marginal returns relative to average returns, and a widening and more risky distribution of payoffs.
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Rascaroli, Laura. How the Essay Film Thinks. Oxford University Press, 2017. http://dx.doi.org/10.1093/acprof:oso/9780190238247.001.0001.
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Less than a decade ago the expression "essay film" was still encountered only sporadically; today, the term has been widely integrated into film criticism, and is increasingly adopted by filmmakers and artists worldwide to characterize their work-while continuing to offer a precious margin of resistance to closed definitions. Eschewing essentialist notions of genre and form, and bringing issues of practice and praxis to the fore, this book offers a novel understanding of the epistemological strategies that are mobilized by the essay film, and of where such strategies operate. On the backdrop of Theodor W. Adorno’s discussion of the essay form’s anachronistic, anti-systematic and disjunctive mode of resistance, and capitalizing on the centrality of the interstice in Gilles Deleuze’s understanding of the cinema as image of thought, the book discusses the essay film as future philosophy-as a contrarian, political cinema whose argumentation engages with us in a space beyond the verbal. A diverse range of case studies discloses how the essay can be a medium of thought on the basis of its dialectic use of audiovisual interstitiality. The book shows how the essay film’s disjunctive method comes to be realized at the level of medium, montage, genre, temporality, sound, narration, and framing-all of these emerging as interstitial spaces of intelligence that illustrate how essayistic meaning can be sustained, often in contexts of political, historical or cultural extremity. The essayistic urge is not to be identified with a fixed generic form, but is rather situated within processes of filmic thinking that thrive in gaps.
Book chapters on the topic "Fixed margins"
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Diaconis, Persi, and Anil Gangolli. "Rectangular Arrays with Fixed Margins." In Discrete Probability and Algorithms, 15–41. New York, NY: Springer New York, 1995. http://dx.doi.org/10.1007/978-1-4612-0801-3_3.
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Tiit, Ene-Margit, and Hele-Liis Helemäe. "Boundary Distributions with Fixed Marginals." In Distributions with given Marginals and Moment Problems, 99–106. Dordrecht: Springer Netherlands, 1997. http://dx.doi.org/10.1007/978-94-011-5532-8_12.
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Tiit, E. M., and E. Käärik. "Generation and Investigation of Multivariate Distributions having Fixed Discrete Marginals." In COMPSTAT, 471–76. Heidelberg: Physica-Verlag HD, 1996. http://dx.doi.org/10.1007/978-3-642-46992-3_65.
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Metry, M. H., and A. R. Sampson. "A Family of Partial Orderings for Positive Dependence Among Fixed Marginal Bivariate Distributions." In Advances in Probability Distributions with Given Marginals, 129–38. Dordrecht: Springer Netherlands, 1991. http://dx.doi.org/10.1007/978-94-011-3466-8_7.
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Yang, Haiqin, Irwin King, Laiwan Chan, and Kaizhu Huang. "Financial Time Series Prediction Using Non-fixed and Asymmetrical Margin Setting with Momentum in Support Vector Regression." In Neural Information Processing: Research and Development, 334–50. Berlin, Heidelberg: Springer Berlin Heidelberg, 2004. http://dx.doi.org/10.1007/978-3-540-39935-3_18.
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Collet, P., and P. Ferrero. "Absolutely Continuous Invariant Measure for Expanding Pick Maps of the Interval Except at a Marginal Fixed Point." In Instabilities and Nonequilibrium Structures II, 27–36. Dordrecht: Springer Netherlands, 1989. http://dx.doi.org/10.1007/978-94-009-2305-8_2.
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"Fixed Margins and Logit Models." In The Analysis of Cross-Classified Categorical Data, 95–119. New York, NY: Springer New York, 2007. http://dx.doi.org/10.1007/978-0-387-72825-4_6.
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Herrin, Judith. "Byzantium." In Margins and Metropolis. Princeton University Press, 2013. http://dx.doi.org/10.23943/princeton/9780691153018.003.0007.
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This chapter examines the mutual relations of palace and city in Byzantium. More specifically, it considers the link between the imperial court within the Great Palace of Constantinople and the local population who called themselves “Byzantines.” Constantine's foundation of a new capital on the site of ancient Byzantion gave rise to a series of epithets for the metropolis: the Queen City, or ruling city, basileuontas polis, as it became known, or simply “the city.” In Constantinople “the palace” refers to the “Great Palace,” even though there were many other palaces in the city and suburban region. The chapter describes the occasions when the emperor had contact with three important groups of people who could enter the palace doors: circus factions, soldiers, and merchants. It also discusses two circumstances in which the emperor left the palace: journeys established by imperial protocol for fixed ceremonies, and unplanned visits to the city.
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Jerabeck, Matthew John, Marc Perkins, and David Petruzzellis. "Microstructure of Fixed Income Trading." In Debt Markets and Investments, 639–58. Oxford University Press, 2019. http://dx.doi.org/10.1093/oso/9780190877439.003.0033.
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Some fixed income securities trade infrequently with high transaction costs. Although equity securities trade mostly on centralized exchanges or platforms, many bonds are inaccessible without an intermediary. Broker-dealers help create a channel between these otherwise illiquid and fractured markets, enabling the flow of information and capital between participants. These agents provide a critical service to developing markets, but they are increasingly threatened by modernization. Two forces are shifting the landscape of fixed income trading: (1) regulation is increasing the cost of business and (2) automation is squeezing profit margins. Although these changes may improve market efficiency in the long-term, they may come at the cost of short-term volatility and price shocks. This chapter describes the microstructure of fixed income trading, focusing on the mechanisms through which prices and liquidity are discovered in the Treasury, corporate, and municipal bond markets.
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Bernardino, C. Robert. "Reconstruction of Canthal Defects." In Surgery of the Eyelid, Lacrimal System, and Orbit. Oxford University Press, 2011. http://dx.doi.org/10.1093/oso/9780195340211.003.0010.
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Reconstruction of the medial and lateral canthal region can be quite challenging because in these two regions, soft tissue (canthal tendons) interacts directly with bony tissue to determine the location and function of the eyelids. Poor knowledge of the anatomy in these regions or poor surgical technique and planning can lead to poorly functioning eyelids in both opening and closing as well as associated lacrimal drainage and pump deficiency and aesthetic asymmetry. Tissue loss in these regions can be from many causes, including trauma, inflammation, and neoplasia. When dealing with malignant neoplasia, it is particularly important to ensure that surgical margins are free of tumor prior to reconstruction. Particularly in the medial canthus, incompletely excised lesions can spread deep into the orbit, into the periocular sinuses (ethmoid and maxillary), and down the nasolacrimal system. Therefore, excision with margin control (Mohs, frozen, or permanent sections) is warranted. When a tumor is heading toward the orbit, this author recommends margin control with permanent fixed tissue to ensure proper diagnosis. When tumor cannot be cleared with this technique an exenteration is offered. Repair of the canthal regions involves first repairing deep structures and any bony defects with autologous or synthetic materials, followed by resuspending eyelid structures to a location analogous to their native location. If remnants of the canthal tendon are present, it can be sutured to periosteum, or sutured or wired to bone through drilled pilot holes. Other techniques may involve using titanium miniplates to fixate the soft tissue to bone. If canthal tendon is not present, periosteum of the orbital rim can be fashioned into a flap simulating a canthal tendon, or the tarsus of the eyelid can be split with one arm forming a new canthal tendon. No matter what technique is used, care must be taken to ensure the tendon or tendon substitute is fixed into the orbit, deeper than the orbital rim; failure to do so will cause the eyelids to function poorly. Once deeper structures are restored, repair of the soft tissue must be undertaken.
Conference papers on the topic "Fixed margins"
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Johansson, Mathias, Erik Bjornemo, and Anders Ahlen. "Fixed Link Margins Outperform Power Control in Energy-Limited Wireless Sensor Networks." In 2007 IEEE International Conference on Acoustics, Speech, and Signal Processing. IEEE, 2007. http://dx.doi.org/10.1109/icassp.2007.366585.
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Garud, Y. S., and David A. Steininger. "Assessment of Uncertainty Sources in Fatigue Usage in Relation to Deterministic Margins, and Sensitivity Analysis." In ASME 2017 Pressure Vessels and Piping Conference. American Society of Mechanical Engineers, 2017. http://dx.doi.org/10.1115/pvp2017-65850.
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Considerations of environmental effects in fatigue have resulted in proposals to augment the original basis and deterministic methods of fatigue assessment, such as in the ASME Code Subarticles NB-3200 and NB-3600. This process of deterministically combining various elements, each with its own set of safety factors, of the CUF-based assessment has the potential to be overly conservative and restrictive in practice. Furthermore, as in the commonly used deterministic design approaches, fixed safety factors are subjectively assigned; as a result the approach does not provide a logical basis to account for uncertainties or variability, and the resulting level of reliability cannot be assessed quantitatively. Therefore, it is useful and desirable to complement the simplicity of deterministic approach by relating the safety factor to target reliability (or probability of meeting the design criterion) so that an appropriately adequate conservatism can be utilized. The feasibility of such an inter-relation and its underlying probabilistic basis were demonstrated in our recent paper that provided a rational basis to account for the significant uncertainties in assessing the CUF-based fatigue including environmental effects. The objective of this paper is to provide further assessment of the above basis for uncertainty quantification and its linkage to deterministic safety factor approach, with additional focus on the quantitative sensitivity analysis of varied sources of uncertainty in the CUF estimation. Results of the case studies implementing the proposed approach combining these uncertainties are presented. New expressions for sensitivity assessment are developed. Results of sensitivity analysis are presented with the goal of demonstrating the sensitivity/ranking of significant contributors to the final CUF uncertainty and the resulting deterministic margins in relation to the target (specified) reliability. The overall approach, also summarized in the paper, utilizes the generally accepted concept of propagation of input uncertainties based on the Taylor series method and the framework of the stress-strength interference technique. The utility and limitations of the approach are discussed in defining the acceptable deterministic margins and in quantifying the impact of various elements of conservatism in the current CUF based fatigue evaluations.
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Mockus, Jonas, Igor Katin, and Joana Katina. "On stochastic simulation of stock-exchange." In International Workshop of "Stochastic Programming for Implementation and Advanced Applications". The Association of Lithuanian Serials, 2012. http://dx.doi.org/10.5200/stoprog.2012.15.
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A simple Stock Exchange Game Model (SEGM) was introduced in (Mockus, 2003) to simulate the behaviour of several stockholders using fixed buying-selling margins at fixed bank yield. In (Mockus, 2010, 2012; Mockus and Raudys, 2010), the theoretical description of the updated model USEGM was presented and illustrated by the results of experimental investigation obtained by the software developed for the early version SEGM. The new elements of the model is the evaluation of the transaction costs and addition of the minimizer of absolute residuals representing the risk-neutral users. Experimental investigation of the updated USEGM model produced new results. In this paper, we discuss them. The results were compared with real data. They show that the traditional estimators of the minimal prediction errors, such as MSE or MAE, do not necessarily provide maximal average profits. However, contrary to the traditional stock rate prediction models, the main objective of USEGM is not forecasting, but simulation of financial time series that are affected by predictions of the participants.
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Vaudrey, Michael A., and William R. Saunders. "Control of Combustor Instabilities Using an Artificial Neural Network." In ASME Turbo Expo 2000: Power for Land, Sea, and Air. American Society of Mechanical Engineers, 2000. http://dx.doi.org/10.1115/2000-gt-0529.
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It is well-known that phase-shifting controllers used for active combustion control must be manually adjusted in order to maintain control over a broad range of operating combustor operating conditions. If one assumes that the thermoacoustic instabilities are linearly stabilizable, then what is needed is a method to determine, and ultimately predict, the frequency response of the plant for any range of operating conditions, so the controller design can be automatically updated to track the changing plant gain/phase relationships that are observed with changing heat release. A unique test-based, design process has been proposed to predict the gain/phase characteristics required of a proportional, phase-shifting controller that can stabilize the thermoacoustic instabilities. In this paper, that process is used to automate the design of a fixed-gain feedback controller that limits the amplitudes of any feedback induced instabilities (to some pre-specified level) while providing the best control of the targeted limit cycling pressure oscillations. The paper describes how a neural network was trained, using the suggested design process, to predict the frequency response of the thermoacoustics in a tube combustor at frequencies adjacent to the limit cycle frequency using certain operating conditions that included a sparsely-sampled temperature profile, total air/fuel flow rate, and equivalence ratio. The neural net training was performed using complex valued, open-loop frequency response function data as the desired signal with the previously mentioned operating conditions as the input signals. (The open loop data was collected for a narrow frequency range surrounding the limit cycle instability by performing a sine dwell at discrete frequencies). Once the neural network was trained, it was used to predict the approximate phase and gain margins as a function of temperature and flow conditions. The margins were then used to automatically update and design a fixed shape feedback controller having the proper phase and magnitude to ensure stability and control in the face of changing operating conditions. A companion paper describes the methodology that underlies the automated design of the feedback controller gain and phase delay.
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Daghigh, M., and S. Helal Makouie. "Application of β-Unzipping Method in Offshore System Reliability Analysis Under Changing Load Pattern." In ASME 2003 22nd International Conference on Offshore Mechanics and Arctic Engineering. ASMEDC, 2003. http://dx.doi.org/10.1115/omae2003-37079.
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This paper is concerned with the reliability assessment of a fixed platform operating in intermediate water depth under extreme environmental conditions. The structure is modelled by two-dimensional frame structure and subjected to quasi-static loads. Extreme wave loads acting on the platform in the unidirectioal mode are estimated together with their probabilistic characteristics. Fully plastic capacities of the members are also treated as random variables. The structure is modelled as a plane truss by using beam-column models and the plastic collapse of the structure is evaluated by using a linearized plasticity condition of the section under effect of axial force to generate the safety margins. For compressional elements, the strength reduction is assumed proportional to the yield stress and for the tension members, it is assumed that the material has a perfect elastic-plastic behavior. Both hydrodynamic drag / inertia forces and slamming loads have been considered in strength and reliabilitry analysis. Using a matrix method, probabilistically dominant collapse modes are selected by applying the β-unzipping method. The system reliability is evaluated by using wave fragility analysis (changing load pattern) and the results have been compared with the fixed load pattern.
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Garud, Y. S. "An Assessment of Uncertainty in Design Factors and Strain-Rate Inputs for Environmentally-Assisted Fatigue and Related Margins." In ASME 2020 Pressure Vessels & Piping Conference. American Society of Mechanical Engineers, 2020. http://dx.doi.org/10.1115/pvp2020-21756.
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Abstract In the case of ASME Class 1 pressure vessels and piping code, as in other similar codes, the design adequacy for fatigue is based on the cumulative usage factor (CUF), with recent augmentation to account for possible environmental effects. This deterministic quantification utilizes several engineering parameters (inputs) and (multiplicative) empirical factors. Although the fixed values of some of these design factors and S–N curves are based on underlying experimental data, the associated uncertainties are not explicit in the resulting fatigue assessment that is effectively based on the singular, calculated quantities of CUF and Fen, projected for a specified service. As such, the resulting fatigue margin and associated conservatism remain implicit or inconsistent and unquantifiable. At the same time, there is an increased demand for either extending the life of existing systems or for new systems with economically viable or better optimized fatigue designs. One approach to address this is to use a more realistic evaluation offered by probabilistic techniques that take into account the various uncertainties. Such an approach to supplement the deterministic analysis was recently proposed by the author keeping the existing and familiar framework of CUF based assessment, while satisfying acceptable component reliability to meet the fatigue design adequacy. The CUF formulation includes an explicit consideration of the k-factors (for material, loading history, surface and size effects) as adjustments to the S–N data. The objective of this paper is to assess the impact of k-factors and their uncertainty on the failure probability and on the number of load-cycles for specified target reliability. Also, similar assessment is made for the impact of strain-rate variable and its uncertainty on the allowable load-cycles. This is illustrated with a typical application of the CUF analysis of a safety injection nozzle safe-end. The approach taken consists of parametric analysis of the CUF-based probability of failure by individually removing the factors and/or their uncertainty, and comparing the results with the base case where all factors and associated uncertainties are maintained at their original values. Results of this analysis and their implications are discussed, along with a generally applicable relation between the deterministic CUF and the probability of failure.
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Schlotter, Michael, and Patrick Keogh. "Recovery Control for Rotors Established in Stable Periodic Contact Modes." In ASME Turbo Expo 2007: Power for Land, Sea, and Air. ASMEDC, 2007. http://dx.doi.org/10.1115/gt2007-27076.
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Previous research has shown that flexible rotors can become established in potentially damaging stable periodic contact modes after initial impact with housings, seals, or auxiliary bearings. These modes are characterized by periodic motion and a fixed contact point in a rotating frame. A contact recovery strategy is developed, with the aim to destabilize the modes and return the rotor to a contact-free orbit. This is achieved by applying compensation forces through magnetic bearings, which reduces the effective synchronous forcing that is causing the contact to a low level. It is shown that even in presence of highly nonlinear contact dynamics, a linear FEM rotor model can be used to calculate appropriate influence coefficients. The contact recovery principle is demonstrated by simulations of a simple disk system and a simple flexible rotor. It is then applied to an experimental flexible rotor test facility. Error margins are investigated, and possible limitations of the method are discussed.
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Fuhrer, Christopher, and Damian M. Vogt. "On the Impact of Simulation Approaches on the Predicted Aerodynamic Damping of a Low Pressure Steam Turbine Rotor." In ASME Turbo Expo 2017: Turbomachinery Technical Conference and Exposition. American Society of Mechanical Engineers, 2017. http://dx.doi.org/10.1115/gt2017-63401.
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The determination of the aerodynamic damping is a major task in predicting flutter stability and therefore safety margins for turbine operation. Throughout the current work the energy method is employed to predict the aerodynamic damping for a last stage rotor blade numerically. The focus is put on the prediction of the aerodynamic damping with different traveling wave mode representations and on the influence of the blade fixation at the root. The Fourier transformation-method, the influence-coefficients-method and a direct traveling wave mode calculation are employed. The investigated rotor geometry was taken from the open literature, a root was designed and an iterative process was installed to determine the cold blade geometry. It became apparent, that the influence-coefficients-method is capable of predicting the overall stability curve computationally efficient, whereas the Fourier-transformation-method showed advantages in the identification of the least stable point for a finer mesh. Nevertheless, all methods predicted a potential flutter risk for the current operating point. The influence of the additional blade root with a completely fixed support on the aerodynamic damping is minor.
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Moroz, Leonid, Leonid Romanenko, Roman Kochurov, and Evgen Kashtanov. "Hydrodynamic Journal Bearings Optimization Considering Rotor Dynamics Restrictions." In ASME Turbo Expo 2018: Turbomachinery Technical Conference and Exposition. American Society of Mechanical Engineers, 2018. http://dx.doi.org/10.1115/gt2018-75790.
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In this study, optimal designs of hydrodynamic journal bearings for 13.5 MW induction motor prototype is developed based on the design of experiment approach and best sequences method which involves entire rotor-bearing system multidisciplinary simulations. These simulations consist of bearing hydrodynamic characteristics calculation and optimization and rotor dynamics analyses for a rotor-bearing system. The results of rotor dynamics analyses are taken into account as the constraints during optimization. Several journal bearings such as plain cylindrical with a different configuration of pockets, elliptical type, and 4-lobe fixed pad have been considered to select the most appropriate design for the application. The bearing clearance, length, diameter, pockets positions, lobe width, oil viscosity, are applied as design input variables. To find the bearing optimal design, following objective functions were considered: 1) Minimum oil film thickness. Optimal bearing clearance is designed to produce the maximum possible level of minimum oil film thickness in order to avoid or reduce possible metal-to-metal contact; 2) Maximization of the performance is done by minimization of friction power loss. 3) Rotor dynamics simulation for the rotor-bearing system is embedded in the optimization process in order to avoid resonances by providing sufficient critical speeds separation margins from operating speed. The methodology for the bearing simulation is based on the mass-conserving mathematical model, proposed by Elrod & Adams and numerical solution for the equations is generated using finite difference method. Rotor dynamics analyses are performed using finite element method. As the result of the study, optimized bearing designs for 13.5 MW induction motor were generated. Optimized bearings provide sufficient frequency margins for critical speeds for the rotor-bearing system and, at the same time, improved hydrodynamic bearing characteristics: maximized oil film thickness and increased efficiency compared to the starting design. Through the considered bearings examples, the study shows how different parameters, such as bearing clearance, length, diameter, and etc., influence key performance characteristics like bearing minimum oil film thickness, friction power losses, rotor-bearing system critical speeds.
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Sipahi, Rifat, and Payam Mahmoodi Nia. "Controller Design With Fixed Delay-Margin for a LTI Unstable Open-Loop Plant: Case Studies." In ASME 2014 Dynamic Systems and Control Conference. American Society of Mechanical Engineers, 2014. http://dx.doi.org/10.1115/dscc2014-6325.
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Around a benchmark open-loop unstable LTI plant with a single delay, we design controllers that create marginal stability of the closed loop at a pre-defined delay margin value τ. These controllers therefore guarantee system stability for all delays less than τ. Case studies covering various scenarios are presented.
Reports on the topic "Fixed margins"
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Leaver, Clare, Owen Ozier, Pieter Serneels, and Andrew Zeitlin. Recruitment, Effort, and Retention Effects of Performance Contracts for Civil Servants: Experimental Evidence from Rwandan Primary Schools. Research on Improving Systems of Education (RISE), September 2020. http://dx.doi.org/10.35489/bsg-rise-wp_2020/048.
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This paper reports on a two-tiered experiment designed to separately identify the selection and effort margins of pay-for-performance (P4P). At the recruitment stage, teacher labor markets were randomly assigned to a pay-for-percentile or fixed-wage contract. Once recruits were placed, an unexpected, incentive-compatible, school-level re-randomization was performed, so that some teachers who applied for a fixed-wage contract ended up being paid by P4P, and vice versa. By the second year of the study, the within-year effort effect of P4P was 0.16 standard deviations of pupil learning, with the total effect rising to 0.20 standard deviations after allowing for selection.
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Caballero, Ricardo, and John Leahy. Fixed Costs: The Demise of Marginal q. Cambridge, MA: National Bureau of Economic Research, March 1996. http://dx.doi.org/10.3386/w5508.
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