Littérature scientifique sur le sujet « Shape replica process »
Créez une référence correcte selon les styles APA, MLA, Chicago, Harvard et plusieurs autres
Consultez les listes thématiques d’articles de revues, de livres, de thèses, de rapports de conférences et d’autres sources académiques sur le sujet « Shape replica process ».
À côté de chaque source dans la liste de références il y a un bouton « Ajouter à la bibliographie ». Cliquez sur ce bouton, et nous générerons automatiquement la référence bibliographique pour la source choisie selon votre style de citation préféré : APA, MLA, Harvard, Vancouver, Chicago, etc.
Vous pouvez aussi télécharger le texte intégral de la publication scolaire au format pdf et consulter son résumé en ligne lorsque ces informations sont inclues dans les métadonnées.
Articles de revues sur le sujet "Shape replica process"
1
Park, Tae Wan, et Woon Ik Park. « Pattern Transfer Printing by Controlling the Deposition Angle to Form Various Patterns ». Korean Journal of Metals and Materials 58, no 2 (5 février 2020) : 145–50. http://dx.doi.org/10.3365/kjmm.2020.58.2.145.
Texte intégralRésumé :
The nanofabrication of modern electronic devices requires advanced nanopatterning technologies. To fabricate desirable nanodevices with excellent device performance, controlling the shape and dimension of the pattern is very important. However, to achieve more facile and faster device fabrication, with better pattern resolution, pattern-tunability, process simplicity, and cost-effectiveness, some remaining challenges still need to be resolved. In this study, we introduce a simple and practical method to generate various patterns using a nanotransfer printing (nTP) process. To obtain functional materials with diverse shapes on a polymer replica pattern, in the nTP process we controlled the angle of deposition before transfer-printing. First, we obtained three different pattern shapes with a thickness of ~ 30 nm on polymethyl methacrylate (PMMA) replica patterns. Then, the deposited functional patterns on the PMMA patterns are successfully transfer-printed onto SiO<sub>2</sub>/Si substrates, showing line, L-shape line, and concavo-convex patterns. We observed the pattern shapes of the patterns by scanning electron microscope (SEM) and optical microscope. Moreover, we systemically analyzed how to form patterns of various shapes using one kind of master mold. We expect that this simple approach will be widely used to fabricate various useful patterns for electronic device applications.
2
Andriani, Claudy, Wahyu Caesarendra, Tegoeh Tjahjowidodo, Tomi Wijaya et Bobby K. Pappachan. « Modal Analysis of Replica Boss Hole During the Deburring Process in Aerospace Manufacturing Industry ». MATEC Web of Conferences 159 (2018) : 02035. http://dx.doi.org/10.1051/matecconf/201815902035.
Texte intégralRésumé :
The monitoring of surface finishing processes in aerospace manufacturing industry becomes one of key issues to maintain the overall quality of product or part. To date, the surface quality monitoring post machining processes such as deburring, use visual inspection, surface roughness test or laser gap gun. The whole manufacturing process then requires a considerable amount of time as the production line must be halted due to these measurements taking place. This study presents an online monitoring system to measure the chamfer quality of replica boss hole post-deburring process. Vibration signal was measured during the deburring process and the features that correlate to the deburring stages (passes) were extracted. This paper focuses on the validation of actual vibration signal with the modal analysis of work coupon (replica boss hole) to obtain the correlation between the vibration amplitude level on particular region and the mode shape of work coupon during the deburring process.
3
Nakamura, Fumi, Kenta Suzuki, Akihiro Noriki et Takeru Amano. « Micromirror fabrication for co-packaged optics using 3D nanoimprint technology ». Journal of Vacuum Science & ; Technology B 40, no 6 (décembre 2022) : 063203. http://dx.doi.org/10.1116/6.0002119.
Texte intégralRésumé :
Co-packaged optics (CPO) is a key technology for addressing power bottlenecks in datacenters by integrating optical and electrical components and replacing electrical wiring with optical links. In the CPO module where silicon chips are embedded on the substrate and polymer waveguides are integrated as optical connections, a pair of 3D micromirrors can achieve low-loss and wideband optical coupling from silicon photonics to polymer waveguides. The shape of the polymer micromirror patterned by grayscale photo lithography depends on process conditions and requires high fabrication accuracy. In this study, photonanoimprint technology is adopted for stable micromirror fabrication. The imprint process for a polymer micromirror was considered from a hyperelastic analysis using the finite element method. The master mold was prepared using grayscale lithography with photosensitive polyimide as a template of a polydimethylsiloxane (PDMS) replica mold. The micromirror fabrication was demonstrated on a 4-in. silicon wafer. By imprinting into a guide groove structure with a PDMS replica mold, over 30 μm-height micromirrors were stably obtained multiple times by a step-and-repeat imprint. The linear part of the patterned mirror by the imprint process was more than 23.5 μm for four times imprinting, and the fabricated mirror shape was improved compared with grayscale lithography. The total height misalignment is 5 μm for 12 mirrors in four imprints, and 70% coupling efficiency in calculation was achieved.
4
Kim, Young Ho, Jeong Woo Sohn, Youngjae Woo, Joo Hyun Hong et Juyoung Park. « Fabrication of PEG Hydrogel and PDMS Microstructures by a Simple UV Curing Process for Nanobio-Chip Applications ». Advanced Materials Research 941-944 (juin 2014) : 404–10. http://dx.doi.org/10.4028/www.scientific.net/amr.941-944.404.
Texte intégralRésumé :
Polyethylene glycol (PEG) hydrogel microstructures with various shapes and sizes on a glass chip were prepared by a simple and rapid ultraviolet (UV) irradiation method using a metal mask. Photocurable PEG solution prepared by mixing 95 wt.% polyethylene glycol diacrylate and 5 wt.% 2-hydroxy-2-methylpropiophenone as a photo-initiator was injected to the gap between bottom and upper glasses in a simply assembled glass chip. After a metal mask with line-and-space or complex patterns was placed on the glass chip, UV light from a spot UV irradiation device was exposed to the glass chip through the metal mask for 7 seconds at UV intensity of 26 mW/cm2. Then the PEG hydrogel micropatterns on the glass chip were obtained after removing unreacted PEG solution by air blowing. To prepare more rigid microstructure, the prepared PEG micropatterned chip was exposed under UV light for 20 seconds. Then the PEG hydrogel micropattern chip was fabricated by a simple and rapid procedure. Micropattern transferring was performed from the PEG hydrogel chip to polydimethyl siloxane (PDMS) replica by a solution casting. The prepared micropatterned PDMS replicas showed similar shape and size of microstructures compared to that of the corresponded PEG hydrogel chip. Thus the PEG hydrogel microstructures on a glass chip could be used as a mold to fabricate micropattern PDMS chips for nanobio-chip applications. Furthermore, the present method provides large scale chip fabrication, more than 4 cm-length and 4 cm-width in a single step, not only PEG hydrogel chips but also PDMS chips.
5
Kwon, Hyuk-Jun, Junyeob Yeo, Jae Jang, Costas Grigoropoulos et Jae-Hyuck Yoo. « Single Pass Laser Process for Super-Hydrophobic Flexible Surfaces with Micro/Nano Hierarchical Structures ». Materials 11, no 7 (17 juillet 2018) : 1226. http://dx.doi.org/10.3390/ma11071226.
Texte intégralRésumé :
Wetting has been studied in various fields: chemical industry, automobile manufacturing, food companies, and even life sciences. In these studies, super-hydrophobic surfaces have been achieved through complex steps and processes. To realize super-hydrophobicity, however, we demonstrated a simple and single pass laser process for the fabrication of micro/nano hierarchical structures on the flexible polytetrafluoroethylene (PTFE, Teflon) surface. The fabricated hierarchical structures helped increase the hydrophobicity by augmenting the surface roughness and promoting air-trapping. In addition, we employed a low-cost and high-throughput replication process producing numerous polydimethylsiloxane (PDMS) replicas from the laser-processed PTFE film. Thanks to the anti-adhesive characteristics of PTFE and the elasticity of PDMS, the structure perfectly transferred to the replica without any mechanical failure. Moreover, our designed mesh patterns offered the possibility of large area applications through varying the process parameters (pitch, beam spot size, laser fluence, and scan speed). Even though mesh patterns had relatively large pitch (190 μm), we were able to achieve high contact angle (>150°). Through pneumatically deformed structure, we clearly showed that the shape of the droplets on our laser-processed super-hydrophobic surface was spherical. Based on these outcomes, we can expect our single laser pulse exposure process can overcome many drawbacks and offer opportunities for advancing applications of the wetting phenomena.
6
Saadat, Mozafar, Marie Taylor, Arran Hughes et Amir M. Hajiyavand. « Rapid prototyping method for 3D PDMS microfluidic devices using a red femtosecond laser ». Advances in Mechanical Engineering 12, no 12 (décembre 2020) : 168781402098271. http://dx.doi.org/10.1177/1687814020982713.
Texte intégralRésumé :
A rapid prototyping technique is demonstrated which uses a red femtosecond laser to produce a metallic mould which is then directly used for the replica moulding of PDMS. The manufacturing process can be completed in less than 6 h making it a viable technique for testing new designs quickly. The technique is validated by creating a microfluidic device with channels of height and depth of 300 µm, with a ramp test structure where the height and width of the channels reduces to 100 µm to demonstrate the techniques 3D capabilities. The resulting PDMS device was easily removed from the metallic mould and closely replicated the shape aside the expected shrinkage during thermal curing. As the technique uses a single replica process, the surface roughness at the base of the channels corresponds to the un-ablated polished metal mould, resulting in a very low surface roughness of 0.361 nm. The ablated metallic mould surface corresponds to the top of the PDMS device, which is bonded to glass and does not affect the flow within the channels, reducing the need for optimisation of laser parameters. Finally, the device is validated by demonstrating laminar flow with the no-slip condition.
7
El Chawich, Ghenwa, Joelle El Hayek, Vincent Rouessac, Didier Cot, Bertrand Rebière, Roland Habchi, Hélène Garay et al. « Design and Manufacturing of Si-Based Non-Oxide Cellular Ceramic Structures through Indirect 3D Printing ». Materials 15, no 2 (8 janvier 2022) : 471. http://dx.doi.org/10.3390/ma15020471.
Texte intégralRésumé :
Additive manufacturing of Polymer-Derived Ceramics (PDCs) is regarded as a disruptive fabrication process that includes several technologies such as light curing and ink writing. However, 3D printing based on material extrusion is still not fully explored. Here, an indirect 3D printing approach combining Fused Deposition Modeling (FDM) and replica process is demonstrated as a simple and low-cost approach to deliver complex near-net-shaped cellular Si-based non-oxide ceramic architectures while preserving the structure. 3D-Printed honeycomb polylactic acid (PLA) lattices were dip-coated with two preceramic polymers (polyvinylsilazane and allylhydridopolycarbosilane) and then converted by pyrolysis respectively into SiCN and SiC ceramics. All the steps of the process (printing resolution and surface finishing, cross-linking, dip-coating, drying and pyrolysis) were optimized and controlled. Despite some internal and surface defects observed by topography, 3D-printed materials exhibited a retention of the highly porous honeycomb shape after pyrolysis. Weight loss, volume shrinkage, roughness and microstructural evolution with high annealing temperatures are discussed. Our results show that the sacrificial mold-assisted 3D printing is a suitable rapid approach for producing customizable lightweight highly stable Si-based 3D non-oxide ceramics.
8
Krumpen, Stefan, Reinhard Klein et Michael Weinmann. « Towards Tangible Cultural Heritage Experiences—Enriching VR-based Object Inspection with Haptic Feedback ». Journal on Computing and Cultural Heritage 15, no 1 (28 février 2022) : 1–17. http://dx.doi.org/10.1145/3470470.
Texte intégralRésumé :
VR/AR technology is a key enabler for new ways of immersively experiencing cultural heritage artifacts based on their virtual counterparts obtained from a digitization process. In this article, we focus on enriching VR-based object inspection by additional haptic feedback, thereby creating tangible cultural heritage experiences. For this purpose, we present an approach for interactive and collaborative VR-based object inspection and annotation. Our system supports high-quality 3D models with accurate reflectance characteristics while additionally providing haptic feedback regarding shape features of the object based on a 3D printed replica. The digital object model in terms of a printable representation of the geometry as well as reflectance characteristics are stored in a compact and streamable representation on a central server, which streams the data to remotely connected users/clients. The latter can jointly perform an interactive inspection of the object in VR with additional haptic feedback through the 3D printed replica. Evaluations regarding system performance, visual quality of the considered models, as well as insights from a user study indicate an improved interaction, assessment, and experience of the considered objects.
9
Lim, Soon Hyuk, Nguyễn Hoàng Ly, Jung A. Lee, Ji Eun Kim, Se-Woong La, Vu Thi Huong, Thi-Giang Tran et al. « Nanopatterned Polymer Molds Using Anodized Aluminum Templates for Anti-Reflective Coatings ». Polymers 13, no 19 (29 septembre 2021) : 3333. http://dx.doi.org/10.3390/polym13193333.
Texte intégralRésumé :
This work introduces a facile geometry-controlled method for the fabrication of embossed and engraved polymeric moth-eye-inspired nanostructures in imprinting molds using anodic aluminum oxide (AAO) templates, resulting in a novel anti-reflective transparent coating. The moth-eye nanostructures are prepared directly on the surface of a flexible polyethylene terephthalate (PET) substrate. As a prerequisite procedure, a UV-curable polyurethane acrylate resin is spun on the PET. The shape of the moth-eye nanostructures can then be adjusted by controlling the size and shape of the nanopores in the AAO templates. Both embossed and concaved polymer moth-eye nanostructures were successfully mounted on a PET substrate. Embossed polymer replica molds were prepared using the AAO master templates in combination with an imprinting process. As revealed by field-emission electron microscope (FE-SEM) images, conical nanopatterns in the AAO template with a diameter of ~90 nm and a depth of ~100 nm, create a homogeneous embossed morphology in the polymer moth-eye nanostructure. The polymeric molds with the depths of 300 and 500 nm revealed the amalgamated structures in their apexes. In addition, a dip-imprinting process of the polymeric layers was implemented to yield a concaved mold by assembly on the surface of the 100 nm embossed polymer mold substrate. Considering that the embossed structures may be crumbled due to their protuberant shapes, the concaved geometries can have an advantage of stability in a certain application concerning physical degradation along with a higher transmission by ~2%, despite somewhat nonuniform structure. The experimental and theoretical results of this study indicate that this polymer layer has the potential for use in anti-reflective coating applications in transparent films.
10
Bae, Eun-Jeong, Hyeong-Kyu Maeng, Ji-Soo Shin, Dong-Wook Park, Young-Wook Park et Dong-Hyun Baek. « Micro-Sphere PDMS for Enhancing Light Extraction in Organic Light-Emitting Devices ». Nanomaterials 12, no 12 (10 juin 2022) : 2007. http://dx.doi.org/10.3390/nano12122007.
Texte intégralRésumé :
We present a micro-sphere PDMS film to improve the external quantum efficiency (EQE) in OLEDs. The micro-sphere PDMS film was fabricated with the breath figure (BF) and replica molding process. The polymer template was prepared through stabilization of the water droplets at the polymer/water interface. The micro-sphere PDMS film was fabricated by pouring PDMS on the polymer template. At a 45 mg/mL concentration, the size of the spheres was approximately 12.3 µm and they had the most circular shape, so this condition yielded the best performance, with an improvement of 33% in the EQE and the widest viewing angle ranging from 0° to 50°. As a result, the sphere film’s size and distribution seem to play important roles in enhancing the EQE in OLEDs. Furthermore, the flexible sphere film based on polymeric materials could offer an effective, large-scale, mass-produced product and a simple process and approach to achieve high efficiency in flexible OLEDs.
Thèses sur le sujet "Shape replica process"
1
BERETTA, MARIO. « Nanostructured mesoporous materials obtained by template synthesis and controlled shape replica ». Doctoral thesis, Università degli Studi di Milano-Bicocca, 2009. http://hdl.handle.net/10281/7502.
Texte intégralRésumé :
Mesoporous nanostructured materials are useful for a widespread field of applications, such as gas storage; selective molecular adsorption; confined chemical reactions and catalysis. In this work, periodic mesoporous silica and organosilica materials, thanks to their high surface area, narrow pore size distribution and high regular structure, have been exploited to obtain nanostructured porous materials with different chemical nature, such as polymer or carbon.
Periodic mesoporous silica objects with defined micrometric shape have been obtained by template synthesis in aqueous medium. A change in synthesis condition of temperature, time and acidity leads to the generation of different shapes such as gyroids, spheres and hollow tubes. Mesoporous silica particles have been exploited for confined polymerization of different monomers (styrene, methylmethacrylate and acrylonitrile) to obtain morphological polymeric nanocomposites. The nanocomposite with polyacrylonitrile has been then heated at high temperature in non-oxidative atmosphere to induce polymer carbonization until the formation of a graphitic-like carbon structure. The silica matrix has been then removed by chemical etching to obtain nanostructured porous materials in polymer and graphitic-like carbon with high surface area and the same micrometric morphology of starting silica matrix (shape replica effect). Afterwards, a periodic mesoporous organosilica system, with phenylene groups directly linked in the wall structure and organized on the molecular scale, has been synthesised, exploited as selective gas adsorption system and heated in non-oxidative atmosphere to obtain a new mesoporous carbon material with high surface area, very regular mesoporous structure and graphitic-like pore walls.
Characterization of these materials has been conduced with X-ray diffraction, calorimetric techniques (DSC and TGA), adsorption of gases and vapours and advanced mono- and bi-dimensional NMR experiments to investigate the interaction between the organic and the inorganic moieties. Thermal evolutions of polyacrylonitrile and phenylene-organosilica have been studied with spectroscopic techniques of ATR and Raman, while the shape replica effect and the high regular pore structure have been directly seen with SEM and TEM microscopies.
Livres sur le sujet "Shape replica process"
1
Hitlin, Steven, et Sarah K. Harkness. Conclusion. Oxford University Press, 2017. http://dx.doi.org/10.1093/oso/9780190465407.003.0010.
Texte intégralRésumé :
The book concludes with this chapter summarizing the general argument, hopefully more compelling in light of our empirical support. Ultimately, we call for researchers to adopt alternate empirical approaches to test our argument that societal inequality is linked to culturally shaped moral codes and emotions. Gathering the data within a country to assess these interactional moral processes is almost prohibitively expensive, so it is difficult to replicate our ideas within a wider array of countries and methodological techniques. However, if this theory has merit, we hope others will pick up on the broad links between macro and micro to refine, or argue with, this admittedly ambitious thesis.
2
Shaffer, Gregory, Manfred Elsig et Sergio Puig. The World Trade Organization’s Dispute Settlement Body. Oxford University Press, 2018. http://dx.doi.org/10.1093/oso/9780198795582.003.0013.
Texte intégralRésumé :
This chapter discusses how the authority of the Appellate Body (AB) of the World Trade Organization (WTO) rapidly became extensive. It nonetheless remains fragile given geopolitical shifts that have helped catalyze the rise of neo-nationalist trade politics in the United States. The establishment of extensive AB authority represented a legalization leap in which international dispute settlement moved from limited narrow authority under the General Agreement on Tariffs and Trade (GATT) to significantly more expansive authority. However, the WTO is an interstate dispute settlement system, so private parties have no direct access to the AB. The AB thus confronts state pressure and at times shapes its decisions to facilitate WTO Member compliance with them. The AB’s authority appears threatened by the US refusal to approve the launching of the selection process to replace retiring AB members. The United States is reacting, in particular, to AB rulings against US import relief practices.
3
Volpi, Frédéric. Revolution and Authoritarianism in North Africa. Oxford University Press, 2017. http://dx.doi.org/10.1093/oso/9780190642921.001.0001.
Texte intégralRésumé :
This book analyses how the Arab uprisings, the sudden wave of leaderless protests that broke out in 2011, could produce regime change in a region until then characterized by authoritarian resilience. It investigates the factors that shaped the trajectories of the uprisings in four North African countries: Morocco, Algeria, Tunisia and Libya. Using an interactionist perspective, it analyzes the three stages of regime change and authoritarian resilience during this wave of uprisings. The first stage corresponds to the implosion of the ruling authoritarian system. This episode is defined by a sharp increase in mobilization of protesters against the regime and the accompanying decrease in the capabilities of the ruling institutions. The second stage corresponds to the reconstruction of practices and discourses around the demands of the protesters and the counter-propositions of the regime to halt the process of deinstitutionalization. This period is marked by the diffusion of new social and political behaviors that challenge and replace preexisting mechanisms of governance or, alternatively, that are subsumed under them. The third stage is the reconstruction of routinized behaviors around a new consensus on governance. This period is characterized by a formal recognition of these new arrangements at home and abroad and by political demobilization.
Chapitres de livres sur le sujet "Shape replica process"
1
Adhikari, Puspa L., Wokil Bam, Pamela L. Campbell, Francois Oberhaensli, Marc Metian, Marc Besson, Hugo Jacob et Peter W. Swarzenski. « Evaluating Microplastic Experimental Design and Exposure Studies in Aquatic Organisms ». Dans Microplastic in the Environment : Pattern and Process, 69–85. Cham : Springer International Publishing, 2021. http://dx.doi.org/10.1007/978-3-030-78627-4_3.
Texte intégralRésumé :
AbstractEnvironmental microplastic particles (MPs) represent a potential threat to many aquatic animals, and experimental exposure studies, when done well, offer a quantitative approach to assess this stress systematically and reliably. While the scientific literature on MP studies in aquatic environments is rapidly growing, there is still much to learn, and this chapter presents a brief overview of some of the successful methods and pitfalls in experimental MP exposure studies. A short overview of some experimental design types and recommendations are also presented. A proper experimental exposure study will yield useful information on MP-organism impacts and must include the following: a comprehensive MP characterization (e.g., density, buoyancy, type, nature, size, shape, concentration, color, degree of weathering/biofilm formation, an assessment of co-contaminant/surfactant toxicity and behavior, an understanding exposure modes, dose and duration, and the type and life stage of the target species). Finally, more conventional experimental considerations, such as time, costs, and access to clean water, specialized instrumentation, and use of appropriate controls, replicate, and robust statistical analyses are also vital. This short review is intended as a necessary first step towards standardization of experimental MP exposure protocols so one can more reliably assess the transport and fate of MP in the aquatic environment as well as their potential impacts on aquatic organisms.
2
López-Pintado, Orlenys, et Marlon Dumas. « Business Process Simulation with Differentiated Resources : Does it Make a Difference ? » Dans Lecture Notes in Computer Science, 361–78. Cham : Springer International Publishing, 2022. http://dx.doi.org/10.1007/978-3-031-16103-2_24.
Texte intégralRésumé :
AbstractBusiness process simulation is a versatile technique to predict the impact of one or more changes on the performance of a process. Mainstream approaches in this space suffer from various limitations, some stemming from the fact that they treat resources as undifferentiated entities grouped into resource pools. These approaches assume that all resources in a pool have the same performance and share the same availability calendars. Previous studies have acknowledged these assumptions, without quantifying their impact on simulation model accuracy. This paper addresses this gap in the context of simulation models automatically discovered from event logs. The paper proposes a simulation approach and a method for discovering simulation models, wherein each resource is treated as an individual entity, with its own performance and availability calendar. An evaluation shows that simulation models with differentiated resources more closely replicate the distributions of cycle times and the work rhythm in a process than models with undifferentiated resources.
3
Atkinson, Sarah. « Digital Film Production Preservation and Access ». Dans From Film Practice to Data Process. Edinburgh University Press, 2018. http://dx.doi.org/10.3366/edinburgh/9780748693580.003.0006.
Texte intégralRésumé :
This chapter examines digital film production preservation and access in the moment of the ‘Digital Dilemma’and the attendant challenges to the archiving of digital film which are summarised as reliability, vulnerability, volume and data complexity. Different archival paradigms are considered including film, born digital and hybrid, and the associated archival aesthetics, drawing from various branches of enquiry within archival studies. This includes considerations of Sally Potter’s own online, interactive archive SP-ARK – whereby all film/analogue was digitised – and the archival structure developed by the Deep Film Access Project (DFAP) – designed to accommodate both film, data and hybrid assets. The chapter contends that archival structures support and replicate auteurism leading to omissions and occlusions of both personnel and practices. Evidence is provided to demonstrate that the way in which an archive is conceived, shaped and organised captures the various ‘aesthetics of production’ and ‘Production Aesthetics’ of a moment in time, as well as its concomitant ‘production legacy aesthetics’, ‘archival legacy aesthetics’ and embedded paradoxes of representation.
4
Bailey, Matthew P., et Joan T. Hallett. « Ice Crystals in Cirrus ». Dans Cirrus. Oxford University Press, 2002. http://dx.doi.org/10.1093/oso/9780195130720.003.0007.
Texte intégralRésumé :
Cirrus is conventionally considered as cloud forming in the Earth's upper troposphere at temperatures somewhat below -40°C, composed of ice crystals and forming long, wispy trails. This characteristic shape, in the form of a curl of hair, results from evaporation in vertical shear of horizontal winds, and leads to its Latin name—originally proposed by Luke Howard in 1803. Here we address the nucleation, growth, and evaporation processes that influence the concentration and shape of individual particles and their role in specific atmospheric phenomena. To set the scene, figure 3.1 shows examples of such crystals collected by aircraft. In this chapter, we also address the radiation and dynamic environment in which crystals grow and subsequently evaporate. Crystal growth depends on the location of a crystal with respect to the cloud edge and the intervening cloud optical thickness; evaporation depends on larger scale processes as at fronts and cumulonimbus anvils and also at inversion interfaces where shear instability and resulting gravity waves produce significant effects over a range of scales. These effects lead to differing cloud radiative properties and ultimately control of the earth's radiation budget and overall climate (Liou 1986; Stephens et al. 1990; Liou and Takano 1994; Takano and Liou 1995; Mishchenko et al. 1996; Strauss et al. 1997; Macke et al. 1998). A growing crystal implies a supersaturated or supercooled environment with respect to the solid phase and can, in general, be considered as growth from either three-fold symmetry overlying a needle, (NASA DC-8,TOGA COARE,-48°C, deep tropical convection, 1993). The replica visually shows a uniformity of color in vertical illumination, indicating a thin crystal a few micrometers thick, uniform to ±0.05 μm. e. Replica of needles, small scalene and triangular three-fold symmetry plates, hexagonal plates, columns, and irregular crystals collected by D.L.R. Falcon in thin cirrus over the Alps, temperature -55°C, October 29,1992. (Courtesy Dr. P. Wendling.) f. Replica of crystals from the evaporating tip of a contrail formed 50 s earlier by the NASA 757 aircraft sampled from the NASA DC-8. Multiple trigonal symmetry crystals are present, with a 60° rotation (left side), along with hexagonal and scalene and triangle crystals, concentration 10/cm3. Clear sky environment over Kansas, temperature -52°C, 1840-1900Z, 4 May 1996.
5
Zhang, Lijun, Guo Qi, Jingjie Kang, Shengming Tang, Yuandong Sun et Ruolan Wang. « Fatigue Life Calculation of Mechanical Seal Welded Metal Bellows ». Dans Advances in Transdisciplinary Engineering. IOS Press, 2022. http://dx.doi.org/10.3233/atde220446.
Texte intégralRésumé :
For welded metal bellows, bellows are used in mechanical seals to replace springs and other auxiliary sealing coils in seals. When the traditional rotating device rotates at a high speed, the moving ring in the mechanical sealing process will cause the axial displacement, and the bellows can compensate or reduce by relying on its own performance. For other mechanical devices, the failure of mechanical seals will directly affect their performance and life, and the failure of welded metal blowers used in mechanical seals is usually considered as fatigue damage. Therefore, studying the welding process of the bellows is extremely important to its service life. This article mainly studies the fatigue life of mechanical seal welded metal bellows. First, the characteristics of mechanical seal welded metal bellows are described by the literature research method, and then the fatigue life calculation method is summarized. Finally, the use of the experimental research method studied the fatigue life of u-shaped metal bellows and v-shaped metal bellows at temperature differences of 3°C, 4°C, 5°C, and 6°C. The experimental results show that as the temperature difference increases, the minimum fatigue life of the two types of metal bellows decreases with decline. At the same time, it can also be found that the minimum fatigue life of the v-shaped metal bellows has always far exceeded U-shaped metal bellows.
6
Palfreyman, David, et Paul Temple. « 7. Futures for the university and college ». Dans Universities and Colleges : A Very Short Introduction, 119–30. Oxford University Press, 2017. http://dx.doi.org/10.1093/actrade/9780198766131.003.0007.
Texte intégralRésumé :
What are the mission and shape, structure and culture, purposes and ambitions of the university and college to be? What is it to be a university and college now—what are they seen ‘to be for’? What might change by 2050? Is it a matter of steady evolution, careful adaptation, gentle re-invention? Or a future of instability and disruptive innovation, radical change, absolute transformation? ‘Futures for the university and college’ considers these questions and suggests that—given the university and college’s role in human capital formation, and the sifting and signalling processes, both hard to replicate without a national higher education structure—it has a relatively assured future.
7
Ekkekakis, Panteleimon, et Mark E. Hartman. « Affective Responses to Exercise ». Dans Sport, Exercise and Performance Psychology, 193–207. Oxford University Press, 2021. http://dx.doi.org/10.1093/oso/9780197512494.003.0014.
Texte intégralRésumé :
Textbooks of exercise psychology describe the relation between exercise and affect with the statement that “exercise makes people feel better.” However, this seems at odds with evidence that most people are not physically active. Reinvestigating this relation with an updated methodology, researchers have found that the “feel better” effect of exercise is present but conditional and that affective responses can predict subsequent physical activity. The following five questions are expected to inspire research in the coming years. First, what are the mechanisms of the “feel better” and “feel worse” responses? Second, how can we improve the affective experience of exercise? Third, how do affective experiences shape memories of exercise? Fourth, can affect-related messages replace traditional exercise promotion campaigns focusing on health benefits? Fifth, how do affective and reflective processes interact in determining exercise behavior?
8
Labonté, Ronald, et Arne Ruckert. « Globalization ». Dans Health Equity in a Globalizing Era, 1–23. Oxford University Press, 2019. http://dx.doi.org/10.1093/oso/9780198835356.003.0001.
Texte intégralRésumé :
Globalization is not a new phenomenon but the rise of industrialization and capitalism changed earlier periods of global expansionism to one that is dominated more by transnational corporations and global capital than by governments and their armies. Globalization is not a singular event, but a confluence of multiple, dynamic, and inter-linked processes. Some of these processes reflect changes in perceptions of time, space, and ideas, while others are shaped primarily by economic relations. The term, globalization, only began to replace an older concept (internationalization) in the 1990s, and was used principally to describe global market integration, hinting at the role economic interests have always played in what many in the world would now describe as ‘globalization’. In overviewing the entire book, this chapter also begins to engage in the debate: is globalization good for health, or bad for health?
9
Rivet, Emily B., Jeffrey M. Stern, Karunasai Mahadevan et Danielle Noreika. « Palliative Care in Transplantation ». Dans Surgical Palliative Care, 148–62. Oxford University Press, 2019. http://dx.doi.org/10.1093/med/9780190858360.003.0013.
Texte intégralRésumé :
Organ transplantation is a field where patients often have significant palliative care needs but frequently lack access to palliative care due to a variety of barriers, including some commonly encountered as well as others specific to this patient population. Organ system failure is necessary to qualify for transplantation. Morbidity and mortality of the particular organ failure syndrome have a profound impact on quality of life. Also, the donor process adds another patient group that may benefit from palliative care. For solid-organ transplant candidates, long waiting times on organ transplant lists and limited organ availability shape the patient experience. Death while waiting for transplant for some conditions is not unusual. Furthermore, there is variability in the ability to replace organ function and how these modalities impact quality of life and end-of-life care. An integrated approach introducing end-of-life planning and palliative care early in the course for patients with organ failure awaiting transplant would improve patient knowledge and possibly symptom management and empower patient decision-making at the end of life.
10
Todes, Daniel P. « 1. Winter at Koltushi ». Dans Ivan Pavlov : A Very Short Introduction, 1—C1.F1. Oxford University PressNew York, 2022. http://dx.doi.org/10.1093/actrade/9780190906696.003.0001.
Texte intégralRésumé :
Abstract Pavlov spent his final winter at his favorite place—his science village in Koltushi, just outside Leningrad. There he struggled to complete two manuscripts—an article on the physiology of psychological processes and a letter to Joseph Stalin’s right-hand man, Vyacheslav Molotov, about the relationship between science, Communism, and Christianity. These manuscripts expressed his lifelong quest to replace uncertainty and chance with scientific certainty. A talented experimenter and driven truth seeker, Pavlov’s scientific style and career were shaped by his personality, the exciting scientific developments of his time, and his biographical trajectory through turbulent times for his beloved Russia. That distinctive scientific style took form in his Nobel Prize–winning studies of digestion and the three decades of research on conditional reflexes that made him a famous, though widely misunderstood, symbol of twentieth-century science.
Actes de conférences sur le sujet "Shape replica process"
1
Yatagawa, Katsuyuki, Masato Nakamura, Masaki Ono, Jun Taniguchi et Shin Hiwasa. « Fabrication of an Antireflective Structure on a Lenticular Lens ». Dans JSME 2020 Conference on Leading Edge Manufacturing/Materials and Processing. American Society of Mechanical Engineers, 2020. http://dx.doi.org/10.1115/lemp2020-8534.
Texte intégralRésumé :
Abstract In our previous study, various lenses with antireflective structures (ARSs) were fabricated by ultraviolet nanoimprint lithography (UV-NIL) and a thin flexible replica mold, which had ARSs. However, in the case of a lens with a large uneven surface such a lenticular lens, it is difficult to transfer an ARS. In this paper, the improvement of the transfer process for a lenticular lens with an ARS is investigated. A master mold of ARSs was fabricated by irradiating glassy carbon with an oxygen ion beam. A flexible replica mold with ARSs was transferred from the ARS master mold by UV-NIL. In this case, the thickness of the flexible replica mold was 210 μm. A lenticular lens with the reverse shape was also transferred from the original lenticular lens by UV-NIL. To add an ARS to the lenticular lens with the reverse shape, it was covered with a flexible replica mold coated with a UV-curable resin. In addition, the lenticular lens was placed on the back side of the flexible replica mold to contact the lens curve properly. Afterwards, the setting samples were pressed with a roll press and simultaneously UV-cured. After this roll press method was carried out, a lenticular lens with the reverse shape and an ARS was obtained. Using this mold, a lenticular lens with an ARS was replicated by UV-NIL and the reverse-shape mold with an ARS.
2
Vergeest, J. S. M., J. J. Broek et J. W. H. Tangelder. « Automatic Prototyping of Complex Geometries for Conceptual Design ». Dans ASME 1990 Design Technical Conferences. American Society of Mechanical Engineers, 1990. http://dx.doi.org/10.1115/detc1990-0026.
Texte intégralRésumé :
Abstract The significance of materialized prototypes from CAD generated mechanical parts has been recognized since more than a decade. Despite the ever increasing quality and speed of graphical visualization methods, solid 3D hard copies from designs remain essential for certain stages in the creation process. Especially during the phase of conceptual geometric design, when alternative shape proposals must be quickly judged, automatic, fast and inexpensive production of replica is of importance. However, for such a kind of prototyping in conjunction with CAD, traditional methods based on CAM and NC technology turn out not adequate. To support conceptual design, several extensions and optimizations, mainly in the software area, need to be effected. In this paper an autonomous NC-milling process generator TLCOR is presented. It evaluates and analyzes surface/solid models based on NURBS, determines the physical constraints of the 3D milling devices (represented in a technical database) and finally produces an ISO-standard control statement sequence. The system selects the appropriate machining method (parametric and/or geometric algorithms) and tools, and breaks up the process into different stages of non-planar path planning with interference avoidance. The user will never be confronted with any aspect concerning the NC. The designer only needs to express his or her wish to obtain a milled copy of the actual CAD model. Extension of TLCOR to shape models defined neutrally (STEP/PDES based) and to multi-axis and robot milling is in progress.
3
Wang, Yafei, Songyan Hu, Guangxu Cheng, Zaoxiao Zhang et Jianxiao Zhang. « Influence of Quenching-Tempering on the Carbide Precipitation of 2.25Cr-1Mo-0.25V Steel Used in Reactor Pressure Vessels ». Dans ASME 2019 Pressure Vessels & Piping Conference. American Society of Mechanical Engineers, 2019. http://dx.doi.org/10.1115/pvp2019-93054.
Texte intégralRésumé :
Abstract The carbide precipitation of 2.25Cr-1Mo-0.25V steel is studied during the head-fabrication heat treatment process using gold replica technique, scanning electron microscopy (SEM), transmission electron microscopy (TEM) and selected area electron diffraction (SAED). Shapes, structures and sizes of carbides before and after heat treatment are analyzed. The dissolution of strip-shaped carbides and the precipitation of granular carbides are confirmed. Amorphous films at the boundaries of carbides are observed by high-resolution transmission electron microscope (HRTEM), which is formed due to the electron irradiation under TEM.
4
Javid, Farhad, Jorge Angeles, Damiano Pasini et Renzo Cecere. « Optimum Design of an Anchoring System for Percutaneous Mitral Valve Repair ». Dans ASME 2010 International Design Engineering Technical Conferences and Computers and Information in Engineering Conference. ASMEDC, 2010. http://dx.doi.org/10.1115/detc2010-28462.
Texte intégralRésumé :
In a novel procedure for percutaneous mitral valve repair, inter-related hook-shaped anchors are inserted around the annulus to replace the surgeon’s suturing in open-heart ring annuloplasty. To properly attach to the tissue, the anchors should withstand large deformation applied during the delivery process and recover their original shape when released into the heart tissue. To this end, stress concentration is avoided along the anchors, which are fabricated of a super-elastic material, by means of shape optimization. Shape optimization consists in finding the smoothest anchor mid-curve possible, which minimizes the von Mises stresses applied during the delivery process. An optimization algorithm aimed at minimizing the weighted rms value of the curvature is introduced. A geometrically optimum shape is obtained by equally weighting the curvature values. Further reduction in the stress values is possible by weighting the curvature values along the anchor in an iterative procedure that yields a structurally optimum anchor. The weights at each iteration are defined proportional to the stress distribution along the anchor obtained in the previous iteration.
5
Trocchianesi, Raffaella, Daniele Duranti et Davide Spallazzo. « Tangible interaction in museums and temporary exhibitions : embedding and embodying the intangible values of cultural heritage ». Dans Systems & Design : Beyond Processes and Thinking. Valencia : Universitat Politècnica València, 2016. http://dx.doi.org/10.4995/ifdp.2016.3322.
Texte intégralRésumé :
Moving from a design perspective, the paper explores the potential of tangible interaction in giving shape to intangible contents in museums and temporary exhibitions. Going beyond tangibility intended in the strict sense of touching assets (Dudley 2010), we use here a wider interpretation of tangibility that considers touch in the sense of embodied experience. In this way we consider as tangible all those experiences that foster a strong involvement of the body. Tangible interaction is interpreted as a practice able to multiply the levels of the narrative, to make the visit experience memorable and to give physicality to intangible values. This approach sees the use of tangible interaction as a way to transfer practices and rituals linked to the contents and representative of the intangible values embedded in the assets. Therefore we can identify “gesture-through” and “object-through” interactions able to enhance the visitor experience and the understanding of cultural heritage. The rituals of gestures is linked to the concept of museum proxemics (author 2013) that involves both sensuousness and movements in space. If proxemics is the discipline which deals with investigating the relationship between individuals and space, and the significance of gestures and distances among people, then museum proxemics relates to the forms of behaviour which govern the relationship between individuals and museum space, between the visitor and the items on display and among visitors. In the paper we outline existing practices by analysing some case studies representative of the potential of tangible interaction in the cultural heritage field and classified according to the categories in the following: - Smart replicas: visitors interact with a technology-enhanced replica of the artworks to feel sensorial aspects and activate further levels of narrative; - Symbolic objects: visitors interact with objects, icons or elements imbued with symbolic meaning as a vehicle to reach the intangible value of the cultural asset; - Touchable screens: visitors interact with a surface mediating their relationship with contents and allowing for a personalised path within them; - Perfoming gestures: visitors perform meaningful gestures in order to trigger specific effects able to stage the narrative of intangible contents. In conclusion we highlight three actions in the cultural experience driven by tangible interaction and matter of design: (i) interacting with a sensitive object able to trigger intangible values; (ii) revealing contents difficult to transmit; (iii) multiplying the levels of knowledge and narrative.DOI: http://dx.doi.org/10.4995/IFDP.2016.3322
6
Jorabchi, Kavous, Joshua Danczyk et Krishnan Suresh. « Shape Optimization of Potentially Slender Structures ». Dans ASME 2008 International Design Engineering Technical Conferences and Computers and Information in Engineering Conference. ASMEDC, 2008. http://dx.doi.org/10.1115/detc2008-50001.
Texte intégralRésumé :
Shape optimization lies at the heart of modern engineering design. Through shape optimization, computers can, in theory, ‘synthesize’ engineering artifacts in a fully automated fashion. However, a serious limitation today is that the evolving geometry (during optimization) may become slender, i.e., beam or plate-like. Under such circumstances, modern 3-D computational methods, such as finite element analysis (FEA), will fail miserably, and so will the shape optimization process. Indeed, the recommended method for analyzing slender artifacts is to replace them with 1-D beams/ 2-D plates, prior to discretization and computational analysis, a process referred to as geometric dimensional reduction. Unfortunately explicit geometric reduction is impractical and hard to automate during optimization since one cannot predict a priori when an artifact will become slender. In this paper, we develop an implicit dimensional reduction method where the reduction is achieved through an algebraic process. The proposed method of reduction is computationally equivalent to explicit geometric reduction for comparable computational cost. However, the proposed method can be easily automated and integrated within a shape optimization process, and standard off-the-shelf 3-D finite element packages can be used to implement the proposed methodology.
7
Bordegoni, Monica, Francesco Ferrise, Mario Covarrubias et Michele Antolini. « A Linear Haptic Interface for the Evaluation of Shapes ». Dans ASME 2009 International Design Engineering Technical Conferences and Computers and Information in Engineering Conference. ASMEDC, 2009. http://dx.doi.org/10.1115/detc2009-86953.
Texte intégralRésumé :
The paper presents a haptic device that allows a user to explore a virtual object along a continuous line. In particular the device is developed with the aim of supporting designers during the evaluation of the aesthetic quality of a virtual product. This is generally done by means of the global and local analysis of the shape in terms of curvature characteristics, presence of inflections points and discontinuities. In order to evaluate such features, designers are used to work on physical prototypes, relying on their skilled sense of touch. It is known that physical prototypes are expensive in terms of cost and time for their realization, and a modification on a physical prototype implies a reverse engineering process for appling such modifications on the virtual model. A linear haptic interface, that adapts its shape reproducing a generic curve on a surface, has been developed to replicate the behavior of a physical strip. This is the way to replace real prototypes with virtual ones without changing the evaluation paradigms that designers are used to. The physical limitations encountered in representing discontinuities in position, tangency and curvature, not renderable by bending and deforming a physical strip, have been overcome thanks to the application of some principles of the theory of haptic illusions by means of sonification of some curve characteristics. The paper describes the linear haptic interface developed and the solution based on haptic illusion that has been implemented to overcome the strip limitations.
8
Bjurstro¨m, Martin, et Carl-Gustaf Hjorth. « Producing HP Pump Barrels Utilizing Powder Metallurgy and Hot Isostatic Pressing ». Dans ASME 2009 International Mechanical Engineering Congress and Exposition. ASMEDC, 2009. http://dx.doi.org/10.1115/imece2009-11209.
Texte intégralRésumé :
The fabrication of near net shape powder metal (PM) components by hot isostatic pressing (HIP) has been an important manufacturing technology for steel and stainless steel alloys since about 1985. The manufacturing process involves inert gas atomization of powder, 3D CAD capsule design, sheet metal capsule fabrication and densification by HIP in very large pressure vessels. Since 1985, several thousand tonnes of parts have been produced. The major applications are found in the oil and gas industry especially in offshore applications, the industrial power generation industry, and traditional engineering industries. Typically, the components replace castings, forgings and fabricated parts and are produced in high alloy grades such as martensitic steels, austenitic stainless steels, duplex (ferritic/austenitic) stainless steels and nickel based superalloys. The application of PM/HIP near net shapes to pump barrels for medium to high pressure use has a number of advantages compared to the traditional forging and welding approach. First, the need for machining of the components is reduced to a minimum and welding during final assembly is reduced substantially. Mechanical properties of the PM/HIP parts are isotropic and equal to the best forged properties in the flow direction. This derives from the fine microstructure using powder powder and the uniform structure from the HIP process. Furthermore, when using the PM HIP process the parts are produced near net shape with supports, nozzles and flanges integrated. This significantly reduces manufacturing lead-time and gives greater design flexibility which improves cost for the final component. The PM HIP near net shape route has received approval from ASTM, NACE and API for specific steel, stainless steel and nickel base alloys. This paper reviews the manufacturing sequence for PM near net shapes and discusses the details of several successful applications. The application of the PM/HIP process to high pressure pump barrels is highlighted.
9
Bjurstro¨m, Martin, et Carl-Gustaf Hjorth. « Producing HP Pump Barrels Utilizing Powder Metallurgy and Hot Isostatic Pressing ». Dans ASME 2009 Pressure Vessels and Piping Conference. ASMEDC, 2009. http://dx.doi.org/10.1115/pvp2009-77787.
Texte intégralRésumé :
The fabrication of near net shape powder metal (PM) components by hot isostatic pressing (HIP) has been an important manufacturing technology for steel and stainless steel alloys since about 1985. The manufacturing process involves inert gas atomization of powder, 3D CAD capsule design, sheet metal capsule fabrication and densification by HIP in very large pressure vessels. Since 1985, several thousand tonnes of parts have been produced. The major applications are found in the oil and gas industry especially in offshore applications, the industrial power generation industry, and traditional engineering industries. Typically, the components replace castings, forgings and fabricated parts and are produced in high alloy grades such as martensitic steels, austenitic stainless steels, duplex (ferritic/austenitic) stainless steels and nickel based superalloys. The application of PM/HIP near net shapes to pump barrels for medium to high pressure use has a number of advantages compared to the traditional forging and welding approach. First, the need for machining of the components is reduced to a minimum and welding during final assembly is reduced substantially. Mechanical properties of the PM/HIP parts are isotropic and equal to the best forged properties in the flow direction. This derives from the fine microstructure using powder powder and the uniform structure from the HIP process. Furthermore, when using the PM HIP process the parts are produced near net shape with supports, nozzles and flanges integrated. This significantly reduces manufacturing lead-time and gives greater design flexibility which improves cost for the final component. The PM HIP near net shape route has received approval from ASTM, NACE and API for specific steel, stainless steel and nickel base alloys. This paper reviews the manufacturing sequence for PM near net shapes and discusses the details of several successful applications. The application of the PM/HIP process to high pressure pump barrels is highlighted.
10
Lüdtke, Klaus. « Centrifugal Process Compressors : Radial vs. Tangential Suction Nozzles ». Dans ASME 1985 International Gas Turbine Conference and Exhibit. American Society of Mechanical Engineers, 1985. http://dx.doi.org/10.1115/85-gt-80.
Texte intégralRésumé :
Experimental investigations were conducted on a radial and a tangential inlet duct to an industrial centrifugal compressor. The tangential nozzle will replace the conventional radial nozzle if a block foundation is used with no pipes allowed on the upper casing half. Models were air tested with and without suction elbows. The tangential duct was tested with various positions of the shaped flow splitter and with variable intake rib angles with the objective to minimize distortions of axial and circumferential velocity profiles and the moment of momentum in the annular eye opening of the impeller. An optimum configuration for the tangential duct was found with smooth profiles and eliminated global vortex at the exit annulus.
Rapports d'organisations sur le sujet "Shape replica process"
1
Bano, Masooda. International Push for SBMCs and the Problem of Isomorphic Mimicry : Evidence from Nigeria. Research on Improving Systems of Education (RISE), juillet 2022. http://dx.doi.org/10.35489/bsg-rise-wp_2022/102.
Texte intégralRésumé :
Establishing School-Based Management Committees (SBMCs) is one of the most widely adopted and widely studied interventions aimed at addressing the learning crisis faced in many developing countries: giving parents and communities a certain degree of control over aspects of school management is assumed to increase school accountability and contribute to improvements in learning. Examining the case of Nigeria, which in 2005 adopted a national policy to establish SBMCs in state schools, this paper reviews the evidence available on SBMCs’ ability to mobilise communities, and the potential for this increased community participation to translate into improved learning. The paper shows that while local community participation can help improve school performance, the donor and state supported SBMCs struggle to stay active and have positive impact on school performance. Yet for ministries of education in many developing countries establishing SBMCs remains a priority intervention among the many initiatives aimed at improving education quality. The paper thus asks what makes the establishment of SBMCs a priority intervention for the Nigerian government. By presenting an analysis of the SBMC-related policy documents in Nigeria, the paper demonstrates that an intervention aimed at involving local communities and developing bottom-up approaches to identifying and designing education policies is itself entirely a product of top-down policy making, envisioned, developed, and funded almost entirely by the international development community. The entire process is reflective of isomorphic mimicry—a process whereby organisations attempt to mimic good behaviour to gain legitimacy, instead of fixing real challenges. Adopting the policy to establish SBMCs, which is heavily promoted by the international development community and does not require actual reform of the underlying political-economy challenges hindering investment in education, enables education ministries to mimic commitment to education reforms and attain the endorsement of the international community without addressing the real challenges. Like all cases of isomorphic mimicry, such policy adoption and implementation has costs: national ministries, as well as state- and district-level education authorities, end up devoting time, resources, and energy to planning, designing, and implementing an intervention for which neither the need nor the evidence of success is established. Additionally, such top-down measures prevent state agencies from identifying local opportunities for delivering the same goals more effectively and perhaps at a lower cost. The paper illustrates this with the case of the state of Kano: there is a rich indigenous culture of supporting community schools, yet, rather than learning why local communities support certain kinds of school but not state schools, and trying to replicate the lessons in state schools, the SBMC model introduced is designed by development agencies at the national level and is administratively complicated and resource-intensive. The opportunity for local learning has not been realised; instead, both the agenda and the implementation framework have been entirely shaped by international aid agencies. The paper thus demonstrates how apparently positive policy interventions resulting from pressure exerted by the international community could be having unintended consequences, given the national-level political-economy dynamics.