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Artigos de revistas sobre o assunto "Resist film removal"
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Mercadier, Thomas, Philippe Garnier, Virginie Loup, Raluca Tiron, Song Zhang, Ayumi Higuchi e Naser Belmiloud. "Evaluation and Optimization of Particle Removal with a Resist Peeling Method". Solid State Phenomena 346 (14 de agosto de 2023): 268–74. http://dx.doi.org/10.4028/p-art4vs.
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The removal of particle contamination is key to maximize yield. Some common particle removal techniques are not relevant anymore when complex and fragile structures are present on the surface. This led to the development of new cleaning processes based on innovative concepts to improve particle removal efficiency without any pattern damage. Some of these processes rely on a resist film lift off. One of these particle removal processes is studied in this paper. The process consists in some resist spin-coating followed by a diluted ammonia dispense to remove this film, which results in particle removal. This specific resist film is made of two immiscible organic polymers. A study was conducted to understand how the organization of these two polymers in the film is key for the film lift-off and the cleaning efficiency. This organization was shown to depend on the substrate contact angle and the resist formulation. A surface preparation is required on hydrophobic surface to reduce their water contact angle and ensure the efficiency of the process. As a result, compared to a high velocity aerosol cleaning technique, this resist peeling process requires multiple steps and a significant process time. A Particle Removal Efficiency study was then performed on blanket wafers to determine and understand how the different process parameters impacted on the cleaning efficiency. It led to the optimization of this process efficiency on blanket wafers. A comparison between an optimized process and a high velocity aerosol cleaning technique underlined the potential of such a process. Compared to high velocity aerosol cleaning, it demonstrated higher efficiency on blanket wafers, without causing any pattern damage on patterned wafers. These results lead to promising perspectives for using this process in the cleaning of fragile structure or targeting small particles with high adhesion.
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Sobhian, Mani. "The Role of Extreme Agitation in Accelerating the Removal Rate of Advanced Packaging Photoresists". Additional Conferences (Device Packaging, HiTEC, HiTEN, and CICMT) 2013, DPC (1 de janeiro de 2013): 001389–416. http://dx.doi.org/10.4071/2013dpc-wp15.
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Negative Dry Film and Negative Spin-On photoresists are widely adopted as the prime choice in wafer-scale packaging processes such as bumping, TSV, and copper pillars. High transparency of negative resist produces vertical profiles with no footing at low exposure energy, resulting in a robust, high throughput lithography process (Doki, 2005). In plating applications, the 3-D cross-linking of negative resist provides good adhesion to wide range of substrates, enabling high-current ECD processes with high throughput. The main challenge of negative photoresist has always been its removal difficulty. Aggressive remover chemistries consisting of DMSO, NMP, and TMAH have been used to cleave, swell, and dissolve the material (Moore, 2002). This paper demonstrates the capabilities of a novel immersion-based strip technology that maintains a constant boundary layer at the wafer surface by providing high-speed agitation to each individual wafer. Results show an acceleration of the removal process, while reduced exposure to remover chemistries reduces risks of bump corrosion. Removal rates of negative dry film and negative spin-on resist materials have been studied across variety of commercially available strip chemistries.
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Hollenbeck, J. L., e R. C. Buchanan. "Oxide thin films for nanometer scale electron beam lithography". Journal of Materials Research 5, n.º 5 (maio de 1990): 1058–72. http://dx.doi.org/10.1557/jmr.1990.1058.
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The exposure response of high resolution oxide resist materials has been examined under high intensity irradiation conditions (∼1 ⊠ 105 A/cm2) to determine the relationships among film characteristics, exposure requirements, and ultimate resolution, and to explore further the processes responsible for ablative exposure. Amorphous films of Al2O3, Y2O3, Sc2O3, 3Al2O3·2SiO2, and MgO·Al2O3 were deposited by rf sputtering onto substrates cooled to –196°C and found to require an exposure dose of approximately 5 ⊠ 103 C/cm2 to complete exposure. Amorphous film structure was found to be necessary to achieve rapid removal of material during exposure. Material properties also found to influence irradiation response and help guide the selection of new materials included ionic character, heat of formation, and melting point. Film thickness was found to influence strongly both exposure requirements and resolution, an optimum thickness occurring at approximately 90 nm in amorphous Al2O3. The dose requirement in 90 nm thick amorphous Al2O3 was determined to be 2.5 ⊠ 103 C/cm2, which is two to three orders of magnitude lower than that of oxide films produced by other techniques. Resolution of the rf sputtered oxide films allowed the production of 5.0 nm holes on 8.1 nm centers. A dedicated STEM was used for exposure studies as well as imaging, microdiffraction analysis, and monitoring of the transmitted beam current, and allowed a qualitative model of the exposure process in rf sputtered oxide resists to be developed.
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Lee, Jong Han, Sang Won Shin, Young Suk Kwon, In Hoon Choi, Chung Nam Whang, Tae Gon Kim e Jong Han Song. "Magnetic Patterning of the Ni/Cu Thin Film by 40 keV O Ion Irradiation". Solid State Phenomena 124-126 (junho de 2007): 867–70. http://dx.doi.org/10.4028/www.scientific.net/ssp.124-126.867.
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Ni(60Å)/Cu film possessing perpendicular magnetic anisotropy (PMA) changes its easy direction into the plane by ion irradiation, due to the relaxation of the strain. By fixing our eyes upon this magnetic property, the magnetic patterning of Ni(60Å)/Cu film using 40 keV O ion irradiation was performed through the photo-resist (PR) mask having 10㎛ x 10 ㎛pattern sizes to pattern the magnetic film. After the PR mask removal of an irradiated film, the magnetic properties were investigated by the magneto-optic Kerr effect and the formation of magnetic pattern was observed by the magnetic force microscopy. The PMA magnetic patterning of epitaxial Ni/Cu film was successfully performed in scale of ㎛ by using ion irradiation, compatible with device process.
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Jimbo, Sadayuki, Kouji Shimomura, Tokuhisa Ohiwa, Makoto Sekine, Haruki Mori, Keiji Horioka e Haruo Okano. "Resist and Sidewall Film Removal after Al Reactive Ion Etching (RIE) Employing F+H2O Downstream Ashing". Japanese Journal of Applied Physics 32, Part 1, No. 6B (30 de junho de 1993): 3045–50. http://dx.doi.org/10.1143/jjap.32.3045.
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Mikalsen Martinussen, Simen, Raimond N. Frentrop, Meindert Dijkstra e Sonia Maria Garcia-Blanco. "Redeposition-Free Deep Etching in Small KY(WO4)2 Samples". Micromachines 11, n.º 12 (24 de novembro de 2020): 1033. http://dx.doi.org/10.3390/mi11121033.
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KY(WO4)2 is a promising material for on-chip laser sources. Deep etching of small KY(WO4)2 samples in combination with various thin film deposition techniques is desirable for the manufacturing of such devices. There are, however, several difficulties that need to be overcome before deep etching of KY(WO4)2 can be realized in small samples in a reproducible manner. In this paper, we address the problems of (i) edge bead formation when using thick resist on small samples, (ii) sample damage during lithography mask touchdown, (iii) resist reticulation during prolonged argon-based inductively coupled plasma reactive ion etching (ICP-RIE), and (iv) redeposited material on the feature sidewalls. We demonstrate the etching of 6.5 µm deep features and the removal of redeposited material using a wet etch procedure. This process will enable the realization of waveguides both in ion-irradiated KY(WO4)2 as well as thin KY(WO4)2 membranes transferred onto glass substrate by bonding and subsequent polishing.
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Tomita, Hiroshi, Minako Inukai, Kaori Umezawa e Li Nan Ji. "Direct Observation of Single Bubble Cavitation Damage for MHz Cleaning". Solid State Phenomena 145-146 (janeiro de 2009): 3–6. http://dx.doi.org/10.4028/www.scientific.net/ssp.145-146.3.
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It is well known that the physical force cleaning such as megasonic (MS) and ultrasonic (US) cleaning are used in FEOL (front-end-of-line) and BEOL (back-end-of-line). Recently, with scaling down below 43 nm, the influence of pattern damage by physical force methods such as MS and US irradiation has been reported. Hence, for the 2x and 3x nm node devices, it will be very difficult to apply MS cleaning for particle removal process without understanding the cavitation force. Cavitation is a complex phenomena based on bubble formation and explosion in the liquid. To control “MS cleaning” and “cavitation” induced pattern damage, many studies using “Sonoluminescence” have been reported. This method is able to demonstrate the existence of high energy fields such as cavitation throughout the megasonic field. The damage clustering distribution was investigated for the damage size and damage length in batch MS conditions using gate structure patterned [1]. In this method, it is difficult to discuss the cavitation force, quantitatively. And this method can not obtain the quantitative physical force on the wafer surface, directly. To understand “cavitation force” induced pattern damage, the observation of “cavitation force” is highlighted with “imaging films” such as blanket aluminum film and resist film, directly.
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Muangtong, Piyanut, Righdan Mohsen Namus e Russell Goodall. "Improved Tribocorrosion Resistance by Addition of Sn to CrFeCoNi High Entropy Alloy". Metals 11, n.º 1 (24 de dezembro de 2020): 13. http://dx.doi.org/10.3390/met11010013.
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Among the high entropy or complex concentrated alloys (HEAs/CCAs), one type of system is commonly based on CoCrFeNi, which as an equiatomic quaternary alloy that forms a single phase FCC structure. In this work, the effect of Sn in an equiatomic quinary system with CoCrFeNi is shown to lead to a great improvement in hardness and resistance to tribocorrosion. The addition causes a phase transition from a single FCC phase in CoCrFeNi to dual phase in CoCrFeNiSn with an Ni-Sn intermetallic phase, and a CoCrFeNi FCC phase. The presence of both the hard intermetallic and this ductile phase helps to resist crack propagation, and consequent material removal during wear. In addition, the high polarization resistance of the passive film formed at the surface and the high corrosion potential of the Ni-Sn phase contribute to preventing chloride corrosion attack during corrosion testing. This film is tenacious enough for the effect to persist under tribocorrosion conditions.
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Farahani, Emad, Andre C. Liberati, Amirhossein Mahdavi, Pantcho Stoyanov, Christian Moreau e Ali Dolatabadi. "Ice Adhesion Evaluation of PTFE Solid Lubricant Film Applied on TiO2 Coatings". Coatings 13, n.º 6 (6 de junho de 2023): 1049. http://dx.doi.org/10.3390/coatings13061049.
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Ice formation affects the performance of many industrial components, including aircraft wings, spacecraft, and power transmission cables. In particular, ice build-up on airplane components increases drag and fuel consumption. A large number of studies have been carried out to reduce ice adhesion by developing passive methods such as icephobic coatings and active ice removal approaches such as mechanical vibrations or chemical-based solutions. Despite remarkable recent breakthroughs in the fabrication of icephobic coatings, passive ice removal solutions require higher durability to resist cyclical mechanical ice detachment treatments. Functionalized TiO2 coatings, applied using the suspension plasma spray (SPS) technique, have been shown to be robust and to have dual-scale characteristics in an ice accretion analysis. In this study, the icephobicity and mechanical durability of a novel duplex coating consisting of polytetrafluoroethylene (PTFE) solid lubricant films on TiO2-coated substrates were evaluated. Notably, various amounts of PTFE were applied on top of the TiO2 coating to identify the ideal quantity required to obtain optimal icephobic properties. Ice was generated in an icing wind tunnel, and the amount of accreted ice was evaluated to assess the anti-icing properties. Wettability parameters, including static water contact angle and contact angle hysteresis, were measured to determine the water mobility and surface energy. Ice shear adhesion to the PTFE-TiO2 duplex coating was measured using a custom-built test rig. The mechanical durability was assessed by measuring the ice shear strength for almost twenty icing–deicing cycles, and after five cycles, the roughness parameters and images taken from the surface of the samples were compared. The combination of PTFE solid lubricant film and TiO2 coating reduced ice adhesion by 70%–90% compared to that of a bare aluminum substrate (reference material). Additionally, the results showed that the application of a uniform layer of PTFE solid lubricant film on dual-scale TiO2 coating significantly reduced ice adhesion and maintained mechanical durability for 25 deicing cycles, making this combination a promising candidate for deicing approaches.
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Limcharoen, Alonggot, Pichet Limsuwan, Chupong Pakpum e Krisda Siangchaew. "Characterisation of C–F Polymer Film Formation on the Air-Bearing Surface Etched Sidewall of Fluorine-Based Plasma Interacting with AL2O3–TiC Substrate". Journal of Nanomaterials 2013 (2013): 1–6. http://dx.doi.org/10.1155/2013/851489.
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C–F polymer redeposition is generated on the etched sidewall of the patterned air-bearing surface (ABS). This C–F polymer is a by-product from fluorine-based plasma using a Surface Technology Systems multiplex-pro air-bearing etch (ABE). The morphology of the re-deposition and the composite element was observed by a scanning electron microscope (SEM). The chemical bonding results were characterised via X-ray photoelectron spectroscopy, attenuated total reflected infrared spectroscopy and visible Raman spectroscopy. The purpose of this work is to demonstrate a modification of AlF3re-deposition to C–F polymer re-deposition, which is easily stripped out by an isopropyl alcohol-based solution. The benefit of this research is the removal of the re-deposition in the resist strip process without additional cleaning process steps.
Teses / dissertações sobre o assunto "Resist film removal"
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Mercadier, Thomas. "Retrait particulaire par étalement et retrait d’un film de résine". Electronic Thesis or Diss., Université Grenoble Alpes, 2023. http://www.theses.fr/2023GRALT095.
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Les étapes de retrait de la contamination particulaire sont cruciales pour l’industrie de la microélectronique afin de maximiser le pourcentage de circuit intégré fonctionnel en fin de fabrication. Cependant, les techniques conventionnelles de retrait particulaire peuvent s’avérer incompatibles avec des structures complexes et fragiles car leur application peut potentiellement causer des dommages physiques. Un procédé innovant basé sur l’étalement temporaire d’un film de résine est étudié dans ce manuscrit. Le principe est fondé sur le décollement du film de résine qui entraine le retrait de la particule en raison des liaisons de surface les reliant. Dans notre cas, la résine utilisée est composée de deux polymères organiques immiscibles. Le procédé consiste en l’étalement de la résine par centrifugation puis en son décollement par une distribution d’ammoniaque dilué à température ambiante. Cette distribution a pour but de dissoudre l’un des deux polymères ce qui provoque la délamination puis le soulèvement du film de résine grâce aux forces de trainée et de portance.Ce manuscrit souligne le rôle de l’organisation des deux polymères non miscibles dans le décollement du film de résine. Cette organisation dépend notamment de l’énergie de surface du substrat. Par exemple il a été montré par des analyses Tof SIMS que le polymère soluble présente une forte affinité avec une surface hydrophile. Une telle organisation sur une surface hydrophile réduit la zone interfaciale devant être délaminée lors de la dispense d’ammoniaque. Par conséquent, le décollement dépend de l’énergie de surface du substrat et n’est réalisable que si elle est supérieure à 66mN/m.Cette organisation spécifique des deux polymères immiscibles peut être ajustée par des paramètres tels que le ratio de mélange ou l’épaisseur de la résine. L’influence de l’ajout d’une étape de recuit après l’étalement a aussi été étudiée. Il a été démontré que ces trois paramètres modifiaient la limite en énergie de surface du décollement du film de résine. Ces paramètres influencent aussi l’efficacité du procédé dans le retrait particulaire. Les mécanismes à l’origine de ces modifications ont été compris permettant l’optimisation du procédé. Ce procédé optimisé a été évalué sur des surfaces structurées. Les résultats ont démontré sa capacité à retirer efficacement des particules tout en préservant l’intégrité des structures.Ces travaux de thèse ont permis de comprendre les mécanismes à l’origine du retrait particulaire à l’aide d’un procédé utilisant le décollement d’une résine et de démontrer la pertinence de cette technique dans un contexte industrielEfficient particle contamination removal is crucial in maximizing yield within the microelectronics industry. However, conventional particle removal techniques may become impractical when dealing with complex and fragile surface structures, as their application can potentially cause physical damage. This challenge has led to the development of new cleaning processes based on innovative concepts, such as a resist film lift off approach. The resist film lift-off leads to the particle removal due to the particle surface bonded to the resist. One of these particle removal processes is studied in this manuscript. In this process, the resist film is composed of two immiscible organic polymers. The process consists of the resist spin-coating followed by a diluted ammonia dispense at room temperature. Thanks to the latter chemical step, one of the polymers is dissolved inducing the delamination and lift-off of the remaining polymer with drag and lift forces.This manuscript sheds light on the critical role of the organization of two immiscible polymers within the resist film in the context of film lift-off. The organization of these polymers was shown to depend on the substrate surface energy through Tof SIMS analysis. For instance, on a hydrophilic substrate, the soluble polymer exhibits a pronounced affinity for the interface. Such an organization on hydrophilic surface minimizes the interfacial area that needs to be delaminated during the resist removal step. Consequently, the effectiveness of ammonia-based film removal relies on the substrate’s surface energy and is only achievable if the substrate surface energy is below 66mN/m.This manuscript provides valuable insights into the modification of the polymers’ organization. The tuning of some parameters from the resist formulation as the blend ratio or the resist thickness and the addition of a bake after the coating are shown to modify this surface energy peeling limit. Additionally, a Particle Removal Efficiency study was conducted on blanket wafers to determine and understand how these three parameters influence cleaning efficiency. It has led to the optimization of process efficiency. This optimized process efficiency was evaluated on structured surfaces. The results showcased its capability to efficiently remove particles while preserving the integrity of delicate structures.This PhD project has contributed to broadening the comprehension of particle removal using a resist peeling process. Moreover, it has demonstrated the potential application of this method in an industrial context
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Massa, Márcia Gomes. "Avaliação de restaurações adesivas bulk fill em molares decíduos após remoção seletiva de tecido cariado : ensaio clínico controlado randomizado". reponame:Biblioteca Digital de Teses e Dissertações da UFRGS, 2018. http://hdl.handle.net/10183/179728.
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O objetivo desta pesquisa foi avaliar o desempenho clínico de restaurações bulk fill em indivíduos com molares decíduos submetidos à RSTC (remoção seletiva de tecido cariado) durante 12 meses de acompanhamento. 62 indivíduos (idade média de 5.9 anos ± 1.74) com no mínimo um molar com lesão cavitada ativa profunda em dentina foram incluídos na pesquisa. 144 molares decíduos foram randomicamente divididos em 2 grupos de material restaurador: Resina Filtek Bulk Fill (grupo teste=FBF) ou Vitremer (grupo controle= CIVMR). Os procedimentos restauradores foram realizados por 2 dentistas especialistas em odontopediatria treinados para realização da técnica e calibrados para avaliação do diagnóstico da atividade da lesão e do desempenho da restauração. Um terceiro examinador também treinado, calibrado e contemplando princípio de cegamento, avaliou as radiografias durante o período de acompanhamento. Os critérios avaliados para determinar o sucesso clínico e radiográfico do tratamento de RSTC foram: ausência de dor espontânea e/ ou sensibilidade à pressão, ausência de sinais de pulpite irreversível, mobilidade anormal incompatível com o período de reabsorção radicular. O desempenho da restauração foi categorizado em cada grupo seguindo o critério da FDI para descoloração marginal, forma anatômica, fratura de material e retenção, adaptação marginal e recorrência de cárie, sendo a falha registrada. Os dentes foram reavaliados clinicamente e radiograficamente quanto o tratamento e desempenho da restauração em 6 e 12 meses. Características sociodemográficas foram registradas no baseline e características clínicas como índice ceod/CPOD, índice de placa visível e índice de sangramento gengival foram registrados durante os períodos de acompanhamento. Os dados foram analisados considerando o tipo de restauração, sintomas, número de faces envolvidas, tipo dente, experiência do operador e padrão de sucesso das restaurações. Para determinar as taxas de sucesso das restaurações foram geradas curvas de sobrevida com o estimador Kaplan-Meyer para cada grupo avaliado. O modelo de regressão de Cox com falhas compartilhadas foi realizado para avaliar diferenças nas taxas de sobrevida das restaurações de acordo com o tratamento e características clínicas e demográficas da amostra. Resultados: A taxa de sucesso das restaurações foi de 83,9% (85,9% para FBF e 81,9% para CIVMR, p = 0,675). Não houve diferenças no risco de falha de acordo com material restaurador. Das 23 falhas, três foram exclusivamente pulpar e uma pulpar e restauradora, e 100% da falha foram causadas por fratura de material. As restaurações oclusoproximais demonstraram a menor taxa de sucesso, aumentando em 4,12 vezes a probabilidade de ter uma falha restauradora em comparação com a restauração oclusal. Os pacientes com perfil “cárie ativos” foram associados a mais falhas do que pacientes “cárie controlados”. O grau de experiência do operador mostrou diferença significativa, e o menos experiente teve mais probabilidade de falhas restauradoras. As restaurações de resina filtek bulk fill realizadas em molares decíduos após a remoção seletiva da cárie mostraram uma sobrevida satisfatória de 85.9% após 12 meses de acompanhamento.The purpose of this study was to evaluate the clinical performance of bulk-fill restorations in primary molars submitted to SCR (selective caries removal) at 12 months of follow-up. 62 (average age of 5.9 years ± 1.74) were included with at least one molar with active cavitated lesion in deep dentin.144 primary molars were randomly divided into 2 groups of restorative material: Filtek Bulk Fill Resin (test group = FBF) or Vitremer (control group = RMGIC). Restorative procedures were performed by 2 specialists in pediatric dentistry trained to perform the technique and calibrated to evaluate the diagnosis of lesion activity and restoration performance. A third examiner also trained, calibrated and contemplating the principle of blinding, evaluated the radiographs during the follow-up period. The criteria evaluated to determine the clinical and radiographic success of the SCR were: absence of spontaneous pain and / or sensitivity to pressure, absence of signs of irreversible pulpitis, abnormal mobility incompatible with the period of root resorption. Restoration performance was categorized in each group following the FDI criteria for marginal staining, anatomical form, fracture of material and retention, marginal adaptation and recurrence of caries, and the failure was recorded. The teeth were reassessed clinically and radiographically regarding the treatment and performance of the restoration at 6 and 12 months. Sociodemographic characteristics were recorded in the baseline and clinical characteristics such as DMFT index, visible plaque index and gingival bleeding index were recorded during the follow - up. The data were analyzed considering the type of restoration, symptoms, number of faces involved, tooth type, operator experience and success rate of the restorations. To determine the success rates of the restorations, survival curves were generated with the Kaplan-Meyer estimator for each group evaluated. The Cox regression model with shared failures was performed to assess differences in survival rates of restorations according to treatment and clinical and demographic characteristics of the sample. Results: Success rate of restorations was 83.9% (85.9% for FBF and 81.9% for RMGIC, p=0.675). There were no differences in the risk of failure according to the material restoration. Of the 23 failures, three failures were exclusive pulp and one pulp and restorative, and 100% of the failure were to due to fracture of material. Occlusoproximal restorations demonstrated the lowest success rate, increases 4.12 times the probability of having a restorative failure compared to occlusal restoration. Patients with "active caries" profile were associated with more failures than "controlled caries" patients. The degree of operator experience showed significant difference, and the less experienced operator had more restorative failures. Bulk Fill composite restorations performed in molar primary teeth after selective caries removal showed satisfactory survival of 85.9% after 12 months of follow-up.
Capítulos de livros sobre o assunto "Resist film removal"
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Yokota, T., T. Hashimoto, M. Otsuka, M. Nobutoki e T. Ueki. "Twist Compression Welding of Aluminum". In Encyclopedia of Aluminum and Its Alloys. Boca Raton: CRC Press, 2019. http://dx.doi.org/10.1201/9781351045636-140000446.
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Diffusion welding of metallic materials requires contact of clean surfaces by removing surface films. However, there is microscopic unevenness on the surfaces and they are covered with oxide layers, absorbed gas layers, contaminating substance layers, etc. Welding is prevented by this unevenness and by these surface films and it is the stability of the surface films, in particular, which affects welding. Aluminium is regarded as a particularly difficult material for diffusion welding since it has a highly stable strong oxide film. Hence, to weld aluminium, it is necessary to remove this stable film so that welding can be performed. This article describes will describe the result of the investigation into the effect of twist angle, welding pressure and temperature, film thickness and surface roughness on the joint strength of the material.
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Suslov, A. A. "Metallic Coatings for Brazing Aluminum Alloys". In Encyclopedia of Aluminum and Its Alloys. Boca Raton: CRC Press, 2019. http://dx.doi.org/10.1201/9781351045636-140000447.
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Because of their high specific strength and satisfactory corrosion resistance, aluminum alloys belong to the group of fundamental structural materials in modern engineering. Their wide use has been made possible as a result of developing advanced methods of processing and producing permanent joints by welding or brazing. However, the application of brazing aluminum alloys is limited because of the problems in removing the strong and chemically resistant oxide film. These problems can be overcome by using metallic coatings which themselves do not oxidize during heating in vacuum and, when deposited, the oxide film is broken up and can be removed from the surface of the parent material. The most promising method is to use metallic coatings in the form of individual components of the brazing alloy which forms in contact melting of the deposited coatings with aluminum in heating for brazing. This brazing method is referred to as contact-reactive brazing and is used widely for brazing aluminum alloys. This article provides an overview of the contact-reactive brazing process.
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Broomfield-McHugh, Dominic. "“Hard to Replace”". In The Oxford Handbook of the Hollywood Musical, 368—C16.N43. Oxford University Press, 2022. http://dx.doi.org/10.1093/oxfordhb/9780197503423.013.22.
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Abstract The critical response to the re-pairing of beloved song-and-dance team Fred Astaire and Ginger Rogers a decade after their ninth and final film for RKO, The Story of Vernon and Irene Castle (1939), was overwhelmingly positive. Yet although it is obvious that the film needs to be read through the lens of the Astaire-Rogers partnership, the project was commissioned for a quite different pairing. Freed was so delighted by the combination of perhaps his two favorite performers, Astaire and Judy Garland, in Easter Parade (1948) that he immediately asked screenwriters Betty Comden and Adolph Green to devise another film for Astaire and Garland as a rapid follow-up. Ultimately, exhaustion and medical problems caused Garland to be unreliable and therefore she was removed from the project—physically, at least—and replaced by Rogers. Yet Garland’s impact on the writing of the screenplay and score of The Barkleys of Broadway was too dominant simply to be written out, leaving the movie with an interesting patina of two especially potent combinations: Astaire-Garland, the popular partnership of the previous year’s hit, and Astaire-Rogers, the much-missed favorite team of the 1930s. This chapter uses archival production sources to consider how the finished movie reflects several competing tensions that the screenwriters, composer, lyricist, and production team had to address as a result of abruptly transforming a movie intended for one stellar partnership into a vehicle for another.
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Jönsson, Alexander, Giacomo Carlo Ferdinando Aliboni, Christina Windmark e Jan-Eric Ståhl. "Strategies for Effective Chip Management in Machining of Ductile Cast Iron". In Advances in Transdisciplinary Engineering. IOS Press, 2024. http://dx.doi.org/10.3233/atde240153.
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A continuously growing and mutating market with increasing demands on environmental sustainability, illuminated by unraveling environmental threats, highlights the need for greater resource efficiency in modern manufacturing industries. Machining has become pivotal in the pursuit of sustainability given its superior efficiency in manufacturing of metallic products. In theory, the efficiency of a machining operation is dictated by the material removal rate and chip formation behavior. However, this may also present additional challenges as chips can be difficult to evacuate from the workpiece, and cause chip carryover. Chip management aims to contain manufacturing costs by addressing this issue and simultaneously pursuing higher machining efficiency. Persistent chips trapped in internal cavities is particularly challenging and can affect quality, and result in costly re-manufacturing, scrapping of portions of produced volume. Effective chip management strategies is therefore crucial to avoid these problems. While there is established research on machining theory and chip removal, proposed solutions are often focused on a specific implementation and lack a holistic perspective on the phenomenon. This study aims to fill this gap in the knowledge by providing a strategic and practical application to tie together information that would otherwise be disaggregated. A case study was conducted to investigate the role of machining, and identify the source of chip carryover and its effect on subsequent production stages. Practical verification demonstrated the effectiveness of the proposed interventions in reducing production costs by decreasing the cycle time and reducing waste, and improving product quality. The future of sustainable manufacturing processes relies on the adoption of strategies and interventions that contribute to the efficiency and sustainability of the manufacturing industry. This study provides a valuable contribution to this effort.
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Mee, Laura. "Genre and Themes". In The Shining, 57–80. Liverpool University Press, 2017. http://dx.doi.org/10.3828/liverpool/9781911325444.003.0004.
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This chapter explores the themes of Stanley Kubrick's The Shining (1980). The Shining, in its themes of family trauma and domestic violence, racial and class tension, all connected through the film's approach to the horror of history, has been criticised for seemingly reducing the supernatural focus of Stephen King's book and replacing it with a more human evil. Like these varied themes and any one of the potential alternative readings, however, the emphasis is ultimately left to the viewer's subjective interpretation. The result, as ever, is the uncertain tone which emphasises the film's horror. The Shining might not quite 'fit' with the independent, low-budget cycle of 1970s American horror cinema which saw the emergence of a new wave of genre auteurs, but it can nonetheless be aligned with a number of that cycle's social allusions, and it be would be remiss to remove the film from this context. Ultimately, Kubrick made The Shining with the intention of achieving commercial success, and looked to the horror genre to achieve this.
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Sengupta, Atanu, e Anirban Hazra. "Growth Theory". In Strategic Infrastructure Development for Economic Growth and Social Change, 74–91. IGI Global, 2015. http://dx.doi.org/10.4018/978-1-4666-7470-7.ch007.
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In this chapter, the authors discuss how the modern thinking of growth starts from the classicists. To the classical economists, limitedness of resources is the limit to growth. Neo-classicists transplanted the natural resources with the producible means of production – capital. Limitedness of resources is removed but it is replaced by the limitedness of operational structure – the firm size. The result is the diminishing returns to capital1 that shape the frontier growth. New growth theorists introduce the concept of generating “ideas” – involving human endeavour with its intellect. This is human capital – the seed of unlimited growth. However, this main story does not cover sharper niceties that are of paramount human interest. Issues of inequality and sustainability are some of these. This chapter is not any encyclopedic attempt. It only tries to cover some of the basic dynamics into which man has fashioned to understand his own destiny.
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Beck, Hermann. "Reactions of Hitler’s Conservative Coalition Partner". In Before the Holocaust, 420—C14.P50. Oxford University PressOxford, 2022. http://dx.doi.org/10.1093/oso/9780192865076.003.0015.
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Abstract Given the vested interest conservatives had evinced in the Prussian/German State and the fact that they had closely identified themselves with the Reich and its political fate since the nineteenth century, some German Jews erroneously assumed in 1933 that Hitler’s conservative alliance partner, the DNVP, might resist what the prominent Weimar German Jewish journalist Georg Bernhard once called “the implementation of Nazi’s racial idiocies.” This hope that conservatives would temper Nazi antisemitism and act as a brake on the realization of its antisemitic program was futile. As this chapter shows, the DNVP and conservatives in general would fulfill none of the expectations placed on them. During the Weimar Republic, the DNVP had excluded Jews from some of its regional organizations and, while the party’s antisemitism abated after 1924, its leadership group and rank-and-file membership were permeated with a cultural anti-Judaism mixed with a political antisemitism that associated Jews with left-wing politics, advocated the removal of “Ostjuden” from Germany, and favored restrictions on Jewish influence. During the period of the Nazi takeover, the DNVP was anxious not to be considered “judenfreundlich,” but at the same time was reluctant to signal to national-minded baptized Jews that to them the party as a whole was off limits. Those DNVP members who were appalled at Nazi attacks emphasized the merits of patriotic German Jews, drew attention to their efforts on Germany’s behalf in the past, and appealed to the party leadership for help. Numerous regional DNVP associations, on the other hand, actually participated in the April boycott. Given the endemic antisemitism of its leaders and most of its members, it was illusory to expect any help from the DNVP as a whole.
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Hoskisson, Robert E., e Michael A. Hitt. "Corporate Governance and Diversification". In Downscoping, 40–57. Oxford University PressNew York, NY, 1994. http://dx.doi.org/10.1093/oso/9780195078435.003.0003.
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Abstract In chapter 2 we discussed the historical development of General Motors and some of the latest changes in management structure. As a result of the restructuring initiated by Stempel before he was forced to step down, by the year 1994 GM expects to close 21 plants and lay off approximately 74,000 employees. Many of these plant closings and employee layoffs will occur in their domestic U.S. auto operations. However, even with these significant changes, the board of directors became restless because of the continued huge losses of net profit, particularly in the North American operations. As a result, the board of directors, led by the outside board members, removed CEO Stempel from the chair of the executive committee of the board. Consequently, Stempel eventually resigned and was replaced as CEO by John Smith. One institutional owner of GM stock noted that “with the plant closings, they shook up the troops, but with this board action, they shook up the generals.” In this chapter we examine how owners and boards of directors, which govern large firms such as GM, affect the strategies formulated by top executives. As boards become more active, their increased role may have both positive and negative outcomes for firm strategy and control. For example, as discussed in chapter 2, there was concern among the outside directors at General Motors that the company needed to make some major changes in its management and operations in order to become more competitive and to stem the tide of net losses. They were not pleased with former CEO Robert Stempel’s slow action and felt that quicker, more radical actions were necessary.
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Baldwin, Peter. "Religion and Science". In The Narcissism of Minor Differences. Oxford University Press, 2010. http://dx.doi.org/10.1093/oso/9780195391206.003.0014.
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Even On Religion, there is reason to question the usual stereotypes of an absolute polarity between the United States and Europe. Let us leave aside the extent to which secularizing Europe is the outlier in a religious world, not the United States. There are religious contrasts, to be sure, between America and Europe, but they are neither as stark nor undifferentiated as is oft en thought. It is frequently said that Americans are more religious than Europeans. These things are hard to quantify, but there is certainly data pointing in that direction. In 1999, a smaller percentage of Americans (1.4%) described themselves as atheists than did Europeans—by a small margin, with the Irish and the Austrians almost indistinguishably close to the Americans (figure 174). But then again, no European country except France (with 14.2%) has more than 8% avowed atheists. The Americans are closer (less than one standard deviation below) to the European mean than are the French, who are more than three standard deviations above it. A smaller percentage of Americans consider themselves religious than the Portuguese and Italians. Proportionately fewer Americans say they believe in God and always have than the Irish and Portuguese, and only a few more than the Italians. A higher percentage of Americans firmly believes in God than northern Europeans, but the numbers are broadly comparable with the Catholic countries (figure 175). If the qualifier “firm” is removed, the American figures become much the same as the Mediterranean nations and, of course, Ireland (figure 176). Again, the United States is closer to the European mean (1.6 standard deviations above) than is the nonbelieving extreme, Sweden, at 1.9 standard deviations below it. Percentage-wise, more Americans (16.4%) attend church more than once a week than in any European nation (Ireland: 13.3%). But fewer Americans, by far, attend church on a weekly basis than the Irish, and the Portuguese and Italians attend at the same rate. The American figure for weekly church attendance is only about as far above the European mean (1.2 standard deviations) as the Danish result (1.07 standard deviations) is below it (figure 177). Over a quarter of Americans report never attending church, the same as the Finns, compared to only 12% of Italians.
Trabalhos de conferências sobre o assunto "Resist film removal"
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Kawai, Akira, Atsushi Ishikawa, Takayoshi Niiyama, Masahiko Harumoto, Osamu Tamada e Masakazu Sanada. "Adhesion and removal behavior of nanoscale bubble on resist film surface for immersion lithography". In Microlithography 2005, editado por John L. Sturtevant. SPIE, 2005. http://dx.doi.org/10.1117/12.599157.
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Eres, Gyula, e Frank Y. C. Hui. "Advanced Lithography for Nanofabrication". In Chemistry and Physics of Small-Scale Structures. Washington, D.C.: Optica Publishing Group, 1997. http://dx.doi.org/10.1364/cps.1997.cma.4.
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Nanostructures are defined to be ultrasmall structures and devices with dimensions less than or equal to 100 nm. Conventional methods for making thin film structures involve exposure of a thin layer of a polymer resist on a suitable substrate to define a pattern, which is than developed and used to fabricate the structures either by deposition, or by etching [1]. The feature sizes of the structures depend both on the resolution of the resist and the imaging method used to expose the resist [1,2]. The materials quality of nanostrustures is also an important factor. In many cases the nanostructures must be crystallographically perfect. Resistless methods of patterning, followed by epitaxial growth could significantly simplify nanofabrication by eliminating a number of processing steps associated with the application, exposure, development, and removal of the resist. The advantage of epitaxial growth is that unlike etching, it is less prone to produce damage in the regions adjacent to the structures. The molecular size effect with polymer based resists such as PMMA is believed to be a significant factor in limiting the resolution (“grain size”) in electron beam lithography (EBL) to 10 nm. Surface adsorption layers such as the hydride layer on the Si surface are characterized by relatively strong chemical bonding which produces a highly uniform coverage that terminates at a single monolayer. Because of these properties surface adsorption layers are attractive candidates as ultrathin, ultrahigh resolution resists for electron beam patterning.
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Lee, Timothy H., Dimitrios C. Kyritsis e Chia-fon F. Lee. "Modeling of Film Boiling and Film Vaporization on Engine Piston Tops". In ASME 2012 Internal Combustion Engine Division Fall Technical Conference. American Society of Mechanical Engineers, 2012. http://dx.doi.org/10.1115/icef2012-92173.
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Engine-out HC emissions resulting from liquid fuel, which escapes from the combustion process, provides the motivation to better understand the film vaporization in a combustion chamber. Previous work theorized that the removal of liquid fuel from the combustion cycle was a result of the increase in film vaporization time due to the Leidenfrost phenomenon. Currently, KIVA 3V predicts a continuous decrease in vaporization time for piston top films. The objective of this work is to improve the KIVA 3V film vaporization model through the inclusion of established boiling correlations, and thus, the Leidenfrost phenomenon. Experimental results have been reviewed from which expressions encompassing high acceleration effects for the nucleate boiling regime and the film boiling regime were investigated, implemented, and validated. Validation was conducted using published experimental data sets for boiling heat flux. As a result of the implementation, a noticeable increase in heat flux occurred due to high accelerations for films in saturated film boiling in both nucleate and film boiling. Computational simulations were conducted using a semi-infinite plate and a direct-injection spark-ignition engine. The semi-infinite plate provided a controlled environment which could separate the effects of pressure and acceleration on film boiling heat flux, film vaporization rates, and film vaporization times. The effect of decreased film vaporization rates, during the Leidenfrost phenomenon, was observed to decrease with increasing acceleration. Finally, the engine computations were used to provide the first film boiling and film vaporization rates for engine fuel films at temperatures above saturation temperature. As a result of this work, a film vaporization model capable of improved prediction of vaporization rates of piston top films in saturated boiling conditions has been created.
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Chen, Haosheng, Darong Chen e Jiadao Wang. "Nano Particles’ Behavior in Chemical Mechanical Polishing With the Effect of Non-Newtonian Properties of Slurry". In World Tribology Congress III. ASMEDC, 2005. http://dx.doi.org/10.1115/wtc2005-63170.
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Particle’s behavior in the slurry with power-law viscosity shows great effect on the wafer surface polishing process. Hydrodynamic pressure is periodically generated on the surface asperity when particles are passing through. Due to the periodical pressure, fatigue fracture occurs and begins from the top to the bottom of the asperity, then the material on the top is removed. Removal rate is calculated based on the energybalance fracture theory, and the result shows good agreement with experiment data. The effects of the particle size and the slurry film thickness are also discussed.
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Linn, J. H., T. K. Thompson e M. G. Shlepr. "Optimizing Contact Resistance at a Resistor/Conductor Interface via Thin Film Microanalysis and Process Design of Experiments". In ISTFA 1999. ASM International, 1999. http://dx.doi.org/10.31399/asm.cp.istfa1999p0161.
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Abstract Electrical data from chromium-silicon-carbon (CrSiC) thin film resistors (tfr) consistently showed highly variable contact resistance (Rc) to the aluminum (Al) interconnect. Transmission electron microscopy data from CrSiC/Al interfaces exhibiting high Rc showed a conformal, amorphous layer sandwiched between the tfr and Al. Auger data from the tfr/Al interface showed this ‘crud’ layer to contain increased C, S, and SiOx. Auger data from CrSiC films on test wafers exposed to the process steps before Al deposition showed additional growth of the ‘crud’ layer after each photoresist (PR) operation. In addition, Rc variability was reduced on product wafers from split lots when 2x the normal PR strip time was used compared to the normal strip time. A Designed Experiment (DOE) to examine improving the removal of this ‘crud’ layer was run on product lots utilizing two factors: the standard strip and a two-step strip. Electrical results for both Rc and die yield were significantly improved using the two-step process. The variability of the Rc was also reduced.
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Krulevitch, Peter, Kirk P. Seward, Harold D. Ackler, George C. Johnson e Roger T. Howe. "Structure and Behavior of Materials for Micromechanical Devices". In ASME 1998 International Mechanical Engineering Congress and Exposition. American Society of Mechanical Engineers, 1998. http://dx.doi.org/10.1115/imece1998-1146.
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Abstract The mechanical behavior of thin film microfabricated devices depends in large part on the material microstructure, which in turn depends on the conditions under which the films are deposited. As a result of material sensitivities to various deposition parameters, new techniques have been developed for thorough characterization and monitoring of film properties such as modulus, residual stress, microactuator force generation, and fatigue. Residual stresses in films, which can lead to fracture, buckling, or curling of surface micromachined devices and can influence microactuator behavior, vary considerably with processing conditions. A study of as-deposited in situ phosphorus doped polycrystalline silicon shows a strong correlation between microstructure and residual stress. The gradient in residual stress through the film thickness was determined by measuring the substrate’s curvature, then etching away a thin layer of the film with a plasma etch, and repeating the process until the entire film was removed. These measurements were then compared with cross-sectional transmission electron micrographs of the films, an example of which is shown in Fig. 1. While the overall stress is compressive, crystallization occurring near the substrate results in a tensile stress component, inducing a stress gradient.
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Lutey, Adrian H. A. "Modelling of Thin-Film Single and Multi-Layer Nanosecond Pulsed Laser Processing". In ASME 2013 International Manufacturing Science and Engineering Conference collocated with the 41st North American Manufacturing Research Conference. American Society of Mechanical Engineers, 2013. http://dx.doi.org/10.1115/msec2013-1093.
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A complete model of nanosecond pulsed laser scribing of arbitrary thin multi-layer structures is presented. The chain of events is separated according to time-scale; an initial simulation considers material response during the pulse; another combines this result with the much slower effects of heat flow away from the laser axis. The former considers heating, vaporisation and phase explosion of metals in the course of a single pulse, accounting for variations in thermal conductivity and optical absorption as the material becomes superheated and approaches its critical temperature. The latter calculates the bidimensional heat flow in a complete multi-layer structure over the course of a scribing operation, combining material properties and considering removal by both short-pulse ablation and long-term heating of the work piece. Simulation results for the single pulse ablation of an aluminium target align well with published experimental data both in terms of phase explosion threshold and ablation depth as a function of fluence. Bidimensional heat flow simulations of a polypropylene–aluminium–polypropylene triplex structure reveal the progression of events towards steady state behaviour; aluminium ejected due to short-pulse ablation and plastic removed due to conduction.
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Yabing, Li, Zhang Han e Xiao Jianjun. "Validation of Film Evaporation Model in GASFLOW-MPI". In 2018 26th International Conference on Nuclear Engineering. American Society of Mechanical Engineers, 2018. http://dx.doi.org/10.1115/icone26-81249.
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A dynamic film model is developed in the parallel CFD code GASFLOW-MPI for passive containment cooling system (PCCS) utilized in nuclear power plant like AP1000 and CAP1400. GASFLOW-MPI is a widely validated parallel CDF code and has been applied to containment thermal hydraulics safety analysis for different types of reactors. The essential issue for PCCS is the heat removal capability. Research shows that film evaporation contributes most to the heat removal capability for PCCS. In this study, the film evaporation model is validated with separate effect test conducted on the EFFE facility by Pisa University. The test region is a rectangle gap with 0.1m width, 2m length, and 0.6m depth. The water film flowing from the top of the gap is heated by a heating plate with constant temperature and cooled by countercurrent air flow at the same time. The test region model is built and analyzed, through which the total thermal power and evaporation rate are obtained to compare with experimental data. Numerical result shows good agreement with the experimental data. Besides, the influence of air velocity, wall temperature and gap widths are discussed in our study. Result shows that, the film evaporation has a positive correlation with air velocity, wall temperature and gap width. This study can be fundamental for our further numerical study on PCCS.
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Fei, Likai, Bin Gao, Pucheng Fan, Haowei Yuan, Husheng Wang, Fuming Yang, Lianyue Du e Lin Zheng. "Preliminary Investigations on the Effect of Cooling Water Boundary Conditions on PCS Performance". In 2022 29th International Conference on Nuclear Engineering. American Society of Mechanical Engineers, 2022. http://dx.doi.org/10.1115/icone29-93163.
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Abstract The coverage of cooling water film outside the containment shell is one of the most important boundary conditions for Passive Containment Cooling System (PCS) of AP/CAP reactor. The reduced coverage of the water film reduces the heat removal capacity of the containment vessel, which may result in the temperature and pressure within the containment can not be kept at a safe level. In this paper, the effect of cooling water flow rate and water film coverage on the heat removal capacity of PCS was studied experimentally under the loss-of-coolant accident (LOCA). Based on the CAP1400 passive containment water distribution test facility, the cooling water boundary conditions were set according to the combination of different cooling water flow rate and water film coverage rate, and the mass energy was released corresponding to the typical design basis accident condition. The response of parameters within the containment obtained from the test was compared and analyzed with the design condition. The experimental results show that the water film coverage rate has a greater impact on the parameters response within the containment than that of the cooling water flow rate.
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Tsai, Li-Chih, Maysam Rezaee, Muhammad Istiaque Haider, Armin Yazdi e Nathan P. Salowitz. "Quantitative Measurement of Thin Film Adhesion Force". In ASME 2019 Conference on Smart Materials, Adaptive Structures and Intelligent Systems. American Society of Mechanical Engineers, 2019. http://dx.doi.org/10.1115/smasis2019-5615.
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Abstract Thin film and micro-fabricated devices are increasingly being used in actuators, sensors, and processors deployed in smart materials. The physical survival of these devices is paramount to their usefulness but existing methods for testing and analysis are limited and challenging due to their properties. The most common test involve the manual application and removal of (unspecified) tape but does not provide a result in scientific units and has large variation (> 35%). This paper presents a study into the effects of parameters of tape application and peeling on the adhesion strength of the tape. This information was then used to create a test methodology using commonly available laboratory equipment, which would control these parameters to minimize variation and produce repeatable quantitative results. Experiments using this test methodology were performed with tape directly adhered to several different substrates as well as tape adhered to a thin film which was then peeled off of a backing. Ongoing work is seeking to identify and address different forms of failure including adhesive failure, cohesive failure, or survival.
Relatórios de organizações sobre o assunto "Resist film removal"
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Waisner, Scott, Victor Medina, Charles Ellison, Jose Mattei-Sosa, John Brasher, Jacob Lalley e Christopher Griggs. Design, construction, and testing of the PFAS Effluent Treatment System (PETS), a mobile ion exchange–based system for the treatment of per-, poly-fluorinated alkyl substances (PFAS) contaminated water. Engineer Research and Development Center (U.S.), março de 2022. http://dx.doi.org/10.21079/11681/43823.
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Poly-,Per-fluorinated alkyl substances (PFAS) are versatile chemicals that were incorporated in a wide range of products. One of their most important use was in aqueous film-forming foams for fighting liquid fuel fires. PFAS compounds have recently been identified as potential environmental contaminants. In the United States there are hundreds of potential military sites with PFAS contamination. The ERDC designed and constructed a mobile treatment system to address small sites (250,000 gallons or less) and as a platform to field test new adsorptive media. The PFAS Effluent Treatment System (PETS) has cartridge filters to remove sediments and a granular activated carbon (GAC) media filter to remove organic compounds that might compete with PFAS in the ion exchange process, although it may also remove PFAS too. The last process is an ion exchange resin specifically designed to remove PFAS to a target level of 70 ng/L or less (equivalent to the US Environmental Protection Agency (EPA) Drinking Water Health Advisory). The system was tested at Hurlburt Field, a US Air Force facility in Florida and at Naval Support Activity (NSA) Mid-South in Millington, TN.
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Christman. L51577 Prediction of SCC Susceptibility Based on Mechanical Properties of Line Pipe Steels. Chantilly, Virginia: Pipeline Research Council International, Inc. (PRCI), agosto de 1988. http://dx.doi.org/10.55274/r0010278.
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If a relationship between the deformation properties of a line pipe steel and its stress-corrosion cracking resistance can be established, then steels may be selected or designed for improved stress-corrosion resistance, based on their mechanical properties. Benefit: In this research program three line pipe steels, removed from long-term service, were examined to determine if there is a correlation between their mechanical properties and stress-corrosion cracking resistance. The hypothesis was that the steel with the greatest tendency for strain hardening, under cyclic and monotonic stress conditions would also have the highest threshold stress for stress-corrosion crack initiation. This hypothesis was verified by the laboratory experiments, which showed the steel with the greatest tendency for strain hardening to have the highest resistance to stress-corrosion. Two other steels, with distinctly lower resistance to plastic deformation, had lower threshold stresses for stress-corrosion. This observation is consistent with the present concept of stress-corrosion crack growth, which holds that crack tip dissolution, and hence crack propagation, occurs because localized plastic deformation ruptures passive films or prevents film formation resulting in crack growth. Result: The cyclic strain behavior of these three steels is consistent with their monotonic stress-strain curves. Both Steels A and B showed a point of extreme strain as the cyclic stress was increased. Their monotonic stress-strain curves both showed well pronounced yield points above which a considerable strain accompanied a small stress increment (low strain hardening). For both steels the rapid increase in cyclic strain occurred at approximately the elevated temperature yield point (\45 ksi for Steel A
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Datta, Sandip, e Geeta Gandhi Kingdon. The Myth and Reality of Teacher Shortage in India: An Investigation Using 2019-20 Data. Research on Improving Systems of Education (RISE), dezembro de 2021. http://dx.doi.org/10.35489/bsg-rise-wp_2020/072.
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This paper examines the widespread perception in India that the country has an acute teacher shortage of about one million teachers in public elementary schools, a view repeated in India’s National Education Policy 2020. Using official DISE data, we show that teacher vacancies cannot be equated with teacher shortages: while the number of teacher vacancies (in teacher-deficit schools) is 766,487, the number of teacher surpluses (in surplus-teacher schools) is 520,141, giving a net deficit of only 246,346 teachers in the country. Secondly, removing estimated fake student numbers from enrolment data greatly reduces the required number of teachers and raises the number of surplus teachers, converting the net deficit of 246,346 teachers into an estimated net surplus of 98,371 teachers. Thirdly, if we both remove estimated fake enrolment and also make a hypothetical change to the teacher allocation rule to adjust for the phenomenon of emptying public schools (which has slashed the national median size of public schools to a mere 63 students, and rendered many schools ‘tiny’), the estimated net teacher surplus rises to 239,800 teachers. Fourthly, we show that if government does fresh recruitment to fill the supposed approximately one-million vacancies as promised in National Education Policy 2020, the already modest national mean pupil-teacher-ratio of 25.1 would fall to 19.9, at a permanently increased fiscal cost of nearly Rupees 637 billion (USD 8.7 billion) per year in 2019-20 prices, which is higher than the individual GDPs of 50 countries that year. The paper highlights the major efficiencies that can result from evidence-based policy on minimum viable school-size, teacher allocation norms, permissible maximum pupil teacher ratios, and teacher deployment.