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[en] STUDY OF KINEMATIC AND DYNAMIC CHARACTERISTICS OF A LARGE-SIZED CHARTPLOTTER / [pt] ESTUDO DAS CARACTERÍSTICAS CINEMÁTICAS E DINÂMICAS DE UMA TRAÇADORA DE GRANDE PORTESANDRA DE ALMIRANTE FRID 09 March 2018 (has links)
[pt] Este trabalho apresenta um estudo experimental do funcionamento do protótipo de uma traçadora gráfica de grande porte, desenvolvida no Departamento de Engenharia Mecânica da PUC-RJ. São detalhadas as características cinemáticas e dinâmicas do modelo de posicionamento adotado. As respostas de traçados são analisadas em função de diversas variáveis. É feito um estudo sobre rampa de aceleração e sua influência na qualidade do traçado. Finalmente, é apresentado um algoritmo, de traçamento de arcos de círculo, que permite maior versatilidade no seu funcionamento. / [en] An experimental study of the performance of a large scale plotter developed and built at the Mechanical Engineering Department of PUC-RJ is undertaken. After analysis of the kinematical solution, the study is concerned with the dynamical response of the pen positioning system. The need of acceleration ramps becomes clear and their influence on the drawing quality is compared for several time delays. Finally, an algorithm for drawing circles and arcs based on a look-up table is presented. This algorithm is suitable for reducing data transfer between the controlling computer and the plotter.
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Advances in optical surface figuring by reactive atom plasma (RAP)Castelli, Marco January 2012 (has links)
In this thesis, the research and development of a novel rapid figuring procedure for large ultra-precise optics by Reactive Atom Plasma technology is reported. The hypothesis proved in this research is that a metre scale surface with a form accuracy of ~1 μm PV can be figure corrected to 20 – 30 nm RMS in ten hours. This reduces the processing time by a factor ten with respect to state-of-the-art techniques like Ion Beam Figuring. The need for large scale ultra-precise optics has seen enormous growth in the last decade due to large scale international research programmes. A bottleneck in production is seen in the final figure correction stage. State-of-the-art processes capable of compliance with requisites of form accuracy of one part in 108 (CNC polishing, Magneto-Rheological Finishing and Ion Beam Figuring) have failed to meet the time and cost frame targets of the new optics market. Reactive Atom Plasma (RAP) is a means of plasma chemical etching that makes use of a Radio Frequency Inductively Coupled Plasma (ICP) torch operating at atmospheric pressure. It constitutes an ideal figuring alternative, combining the advantages of a non-contact tool with very high material removal rates and nanometre level repeatability. Despite the rapid figuring potential of this process, research preceding the work presented in this manuscript had made little progress towards design and implementation of a procedure for metre-class optics. The experimental work performed in this PhD project was conducted on Helios 1200, a unique large-scale RAP figuring facility at Cranfield University. Characterisation experiments were carried out on ULE and fused silica surfaces to determine optimum process parameters. Here, the influence of power, surface distance, tool speed and surface temperature was investigated. Subsequently, raster-scanning tests were performed to build an understanding on spaced multiple passes ... [cont.].
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A two-point diagnostic for the H ii galaxy Hubble diagramLeaf, Kyle, Melia, Fulvio 03 1900 (has links)
A previous analysis of starburst-dominated HII galaxies and HII regions has demonstrated a statistically significant preference for the Friedmann-Robertson-Walker cosmology with zero active mass, known as the R-h = c(t) universe, over Lambda cold dark matter (Lambda CDM) and its related dark-matter parametrizations. In this paper, we employ a two-point diagnostic with these data to present a complementary statistical comparison of Rh = ct with Planck Lambda CDM. Our two-point diagnostic compares, in a pairwise fashion, the difference between the distance modulus measured at two redshifts with that predicted by each cosmology. Our results support the conclusion drawn by a previous comparative analysis demonstrating that Rh = ct is statistically preferred over Planck Lambda CDM. But we also find that the reported errors in the HII measurements may not be purely Gaussian, perhaps due to a partial contamination by non-Gaussian systematic effects. The use of HII galaxies and HII regions as standard candles may be improved even further with a better handling of the systematics in these sources.
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Discovery of a Protocluster Associated with a Ly α Blob Pair at z = 2.3Bădescu, Toma, Yang, Yujin, Bertoldi, Frank, Zabludoff, Ann, Karim, Alexander, Magnelli, Benjamin 23 August 2017 (has links)
Bright Ly alpha blobs (LABs)-extended nebulae with sizes of similar to 100 kpc and Ly alpha luminosities of similar to 10(44) erg s(-1)-often reside in overdensities of compact Ly alpha emitters (LAEs) that may be galaxy protoclusters. The number density, variance, and internal kinematics of LABs suggest that they themselves trace group-like halos. Here, we test this hierarchical picture, presenting deep, wide-field Ly alpha narrowband imaging of a 1 degrees x. 0 degrees.5 region around a LAB pair at z = 2.3 discovered previously by a blind survey. We find 183 Lya emitters, including the original LAB pair and three new LABs with Ly alpha luminosities of (0.9-1.3) x 10(43) erg s(-1) and isophotal areas of 16-24 arcsec2. Using the LAEs as tracers and a new kernel density estimation method, we discover a large-scale overdensity (Bootes J1430+3522) with a surface density contrast of delta(Sigma) = 2.7, a volume density contrast of delta similar to 10.4, and a projected diameter of approximate to 20 comoving Mpc. Comparing with cosmological simulations, we conclude that this LAE overdensity will evolve into a present-day Coma-like cluster with log(M/M-circle dot) similar to 15.1 +/- 0.2. In this and three other wide-field LAE surveys re-analyzed here, the extents and peak amplitudes of the largest LAE overdensities are similar, not increasing with survey size, and implying that they were indeed the largest structures then and today evolve into rich clusters. Intriguingly, LABs favor the outskirts of the densest LAE concentrations, i.e., intermediate LAE overdensities of delta(Sigma) = 1-2. We speculate that these LABs mark infalling protogroups being accreted by the more massive protocluster.
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Analysing H(z) data using two-point diagnosticsLeaf, Kyle, Melia, Fulvio 09 1900 (has links)
Measurements of the Hubble constantH(z) are increasingly being used to test the expansion rate predicted by various cosmological models. But the recent application of two-point diagnostics, such as Om(zi, zj) and Omh(2)(zi, zj), has produced considerable tension between Lambda CDM's predictions and several observations, with other models faring even worse. Part of this problem is attributable to the continued mixing of truly model-independent measurements using the cosmic-chronometer approach, and model-dependent data extracted from baryon acoustic oscillations. In this paper, we advance the use of two-point diagnostics beyond their current status, and introduce new variations, which we call Delta h(zi, zj), that are more useful for model comparisons. But we restrict our analysis exclusively to cosmic-chronometer data, which are truly model independent. Even for these measurements, however, we confirm the conclusions drawn by earlier workers that the data have strongly non-Gaussian uncertainties, requiring the use of both 'median' and 'mean' statistical approaches. Our results reveal that previous analyses using two-point diagnostics greatly underestimated the errors, thereby misinterpreting the level of tension between theoretical predictions and H(z) data. Instead, we demonstrate that as of today, only Einstein-de Sitter is ruled out by the two-point diagnostics at a level of significance exceeding similar to 3s. The R-h = ct universe is slightly favoured over the remaining models, including Lambda cold dark matter and Chevalier-Polarski-Linder, though all of them (other than Einstein-de Sitter) are consistent to within 1 sigma with the measured mean of the Delta h(zi, zj) diagnostics.
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Assimilating satellite-based canopy height within an ecosystem model to estimate aboveground forest biomassJoetzjer, E., Pillet, M., Ciais, P., Barbier, N., Chave, J., Schlund, M., Maignan, F., Barichivich, J., Luyssaert, S., Hérault, B., von Poncet, F., Poulter, B. 16 July 2017 (has links)
Despite advances in Earth observation and modeling, estimating tropical biomass remains a challenge. Recent work suggests that integrating satellite measurements of canopy height within ecosystem models is a promising approach to infer biomass. We tested the feasibility of this approach to retrieve aboveground biomass (AGB) at three tropical forest sites by assimilating remotely sensed canopy height derived from a texture analysis algorithm applied to the high-resolution Pleiades imager in the Organizing Carbon and Hydrology in Dynamic Ecosystems Canopy (ORCHIDEE-CAN) ecosystem model. While mean AGB could be estimated within 10% of AGB derived from census data in average across sites, canopy height derived from Pleiades product was spatially too smooth, thus unable to accurately resolve large height (and biomass) variations within the site considered. The error budget was evaluated in details, and systematic errors related to the ORCHIDEE-CAN structure contribute as a secondary source of error and could be overcome by using improved allometric equations.
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Functionalization and large scale assembly of carbon nanotubesMajumder, Anindya 23 June 2016 (has links) (PDF)
Assembly of nanoparticles provides effective building blocks for physical, chemical and biological systems which have surprisingly collective intrinsic physical properties. One-dimensional nanomaterials are one of the most spectacular and promising candidates for technological application in the field of nanotechnology. Single-walled carbon nanotubes represent an anisotropic and perfectly one-dimensional group of nanomaterials with extraordinary electronic, mechanical, chemical and thermal properties. Usually, such nanoparticles are dispersed in solution, and for any application it’s necessary to bring them on the surface in an organized way. However, to exploit its full potential and to ensure efficient scale-up, self assembly of such nanoparticles is absolutely essential. The aim of this work is to develop new strategies for alignment by self assembly of such one-dimensional nanomaterials like carbon nanotubes using combination of different conventional techniques.
This includes a functionalization study with new strategy for hybrid bio-functionalization of carbon nanotubes which could have potential application in drug delivery, genetic engineering and biosensors. The possibility to make hybrid structure functionalization by attaching ss-DNA backbone to the positively charged head group of a cationic surfactant by ionic interaction is demonstrated. Localization of nanoparticles at liquid-liquid interfaces by manipulating the particle surface energy is an upcoming area with great potential for research and opens a window to fabricate self assembled interfacial structured hybrid materials with unique properties. In this direction, a strategy for alignment of carbon nanotubes at liquid-liquid interfaces using dielectrophoresis is also investigated. Finally, a new and unique strategy for large scale alignment of carbon nanotubes is presented by combing dielectrophoresis during Langmuir-Blodgett assembly process. The degree of alignment is verified using polarized micro Raman spectroscopy and direction dependent electrical conductivity measurements. / Die Assemblierung von Nanopartikeln liefert effektive Bausteine für physikalische, chemische und biologische Systeme, welche erstaunliche kollektive und spezifische Eigenschaften aufweisen. Eindimensionale Nanopartikel sind mitunter die spektakulärsten und vielversprechendsten Materialien für technologische Anwendungen im Feld der Nanotechnologie. Einzelwand-Kohlenstoffnanoröhren stellen eine Gruppe von anisotropen und perfekt eindimensionalen Nanopartikeln mit außergewöhnlichen elektronischen, mechanischen, chemischen und thermischen Eigenschaften dar. Im Allgemeinen befinden sich solche Nanopartikel in gelöster Form. Für alle Arten der Anwendung müssen diese notwendigerweise in organisierter Weise auf Oberflächen abgeschieden werden. Um ihr volles Potential auszuschöpfen und eine effiziente Hochskalierbarkeit zu erreichen, ist eine Self Assembly solcher Objekte zwingend erforderlich.
Ziel dieser Arbeit ist es, neue Strategien für Ausrichtung und Self Assembly von eindimensionalen Nanopartikeln wie Kohlenstoffnanoröhren mit einer Kombination von konventionellen Techniken zu entwickeln. Dies beinhaltet eine Funktionalisierungsstudie mit neuer Strategie für hybrid-bio-Funktionalisierung von Kohlenstoffnanoröhren, welche eine potentielle Anwendungsmöglichkeit in der Medikamentenverabreichung, Gentechnik und Biosensoren darstellt. Die Möglichkeit hybride Struktur Funktionalisierung durch Anfügen von ss-DNA-Rückgrat der positiv geladenen Kopf Gruppe der kationischen Tensiden durch Ionische Wechselwirkung wird demonstriert. Eine Anreicherung von Flüssigkeits-Flüssigkeits-Grenzflächen mit Nanopartikeln durch Kontrolle der Partikel Oberflächenenergie ist ein neus Forschungsgebiet mit großem Potential für die Forschung, welche, die Möglichkeit eröffnet, selbst-organisierte, grenzflächenstrukturierte Hybridmaterialien mit einzigartigen Eigenschaften herzustellen. Anknüpfend hieran wird auch eine Strategie zur Ausrichtung von Kohlenstoffnanoröhren an Grenzflächen mittels Dielektrophorese untersucht. Letztlich wird eine neuentwickelte, einzigartige Strategie zur großflächigen Ausrichtung von Kohlenstoffnanoröhren vorgestellt, welche auf einer Kombination von Dielektrophorese und Langmuir-Blodgett-Technik durch gleichzeitige Anwendung im Anordnungsprozess beruht. Der Grad der Ausrichtung ist mit polarisierten Mikro Raman-Spektroskopie und Richtung abhängige elektrische Leitfähigkeit Messungen überprüft.
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Identification décentralisée des systèmes de grande taille : approches appliquées à la thermique des bâtiments / Decentralized identification of large scale-systems : approaches used to thermal applications in buildingsJedidi, Safa 15 December 2016 (has links)
Avec la complexité croissante des systèmes dynamiques qui apparaissent dans l'ingénierie et d'autres domaines de la science, l'étude des systèmes de grande taille composés d'un ensemble de sous-systèmes interconnectés est devenue un important sujet d'attention dans différents domaines, tels que la robotique, les réseaux de transports, les grandes structures spatiales (panneaux solaires, antennes, télescopes,...), les bâtiments,… et a conduit à des problèmes intéressants d'analyse d'identification paramétrique, de contrôle distribué et d'optimisation. L'absence d'une définition universelle et reconnue des systèmes qu'on appelle "grands systèmes", "systèmes complexes", "systèmes interconnectés",..., témoigne de la confusion entre ces différents concepts et la difficulté de définir des limites précises pour tels systèmes. L'analyse de l'identifiabilité et de l'identification de ces systèmes nécessite le traitement de modèles numériques de grande taille, la gestion de dynamiques diverses au sein du même système et la prise en compte de contraintes structurelles (des interconnections,...). Ceci est très compliqué et très délicat à manipuler. Ainsi, ces analyses sont rarement prises en considération globalement. La simplification du problème par décomposition du grand système en sous-problèmes de complexité réduite est souvent la seule solution possible, conduisant l'automaticien à exploiter clairement la structure du système.Cette thèse présente ainsi, une approche décentralisée d'identification des systèmes de grande taille "large scale systems" composés d'un ensemble de sous-systèmes interconnectés. Cette approche est basée sur les propriétés structurelles (commandabilité, observabilité et identifiabilité) du grand système. Cette approche à caractère méthodologique est mise en œuvre sur des applications thermiques des bâtiments. L'intérêt de cette approche est montré à travers des comparaisons avec une approche globale. / With the increasing complexity of dynamical systems that appear in engineering and other fields of science, the study of large systems consisting of a set of interconnected subsystems has become an important subject of attention in various areas such as robotics, transport networks, large spacial structures (solar panels, antennas, telescopes, \ldots), buildings, … and led to interesting problems of parametric identification analysis, distributed control and optimization. The lack of a universal definition of systems called "large systems", "complex systems", "interconnected systems", ..., demonstrates the confusion between these concepts and the difficulty of defining clear boundaries for such systems. The analysis of the identifiability and identification of these systems requires processing digital models of large scale, the management of diverse dynamics within the same system and the consideration of structural constraints (interconnections, ...) . This is very complicated and very difficult to handle. Thus, these analyzes are rarely taken into consideration globally. Simplifying the problem by decomposing the large system to sub-problems is often the only possible solution. This thesis presents a decentralized approach for the identification of "large scale systems" composed of a set of interconnected subsystems. This approach is based on the structural properties (controllability, observability and identifiability) of the global system. This methodological approach is implemented on thermal applications of buildings. The advantage of this approach is demonstrated through comparisons with a global approach.
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A Large-scale Dynamic Vector and Raster Data Visualization Geographic Information System Based on Parallel Map TilingWang, Huan 08 November 2011 (has links)
With the exponential increasing demands and uses of GIS data visualization system, such as urban planning, environment and climate change monitoring, weather simulation, hydrographic gauge and so forth, the geospatial vector and raster data visualization research, application and technology has become prevalent. However, we observe that current web GIS techniques are merely suitable for static vector and raster data where no dynamic overlaying layers. While it is desirable to enable visual explorations of large-scale dynamic vector and raster geospatial data in a web environment, improving the performance between backend datasets and the vector and raster applications remains a challenging technical issue.
This dissertation is to implement these challenging and unimplemented areas: how to provide a large-scale dynamic vector and raster data visualization service with dynamic overlaying layers accessible from various client devices through a standard web browser, and how to make the large-scale dynamic vector and raster data visualization service as rapid as the static one. To accomplish these, a large-scale dynamic vector and raster data visualization geographic information system based on parallel map tiling and a comprehensive performance improvement solution are proposed, designed and implemented. They include: the quadtree-based indexing and parallel map tiling, the Legend String, the vector data visualization with dynamic layers overlaying, the vector data time series visualization, the algorithm of vector data rendering, the algorithm of raster data re-projection, the algorithm for elimination of superfluous level of detail, the algorithm for vector data gridding and re-grouping and the cluster servers side vector and raster data caching.
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Seismic Retrofitting of Conventional Reinforced Concrete Moment-Resisting Frames Using Buckling Restrained BracesAl-Sadoon, Zaid January 2016 (has links)
Reinforced concrete frame buildings designed and built prior to the enactment of modern seismic codes of the pre-1970’s era are considered seismically vulnerable, particularly when they are subjected to strong ground motions. It is the objective of this research to develop a new and innovative seismic retrofit technology for seismic upgrading of nonductile or limited ductility reinforced concrete frame buildings involving the implementation of buckling restrained braces. To achieve this objective, combined experimental and analytical research was conducted. The experimental research involved tests of large-scales reinforced concrete frames under slowly applied lateral deformation reversals, and the analytical research involved design and nonlinear analysis of laboratory specimens, as well as design and dynamic inelastic response history analysis of selected prototype buildings in eastern and western Canada. The research project started with a comprehensive review of the building code development in Canada to assess the progression of seismic design requirements over the years, and to select a representative period within which a significant number of engineered buildings were designed and constructed with seismic deficiencies. A similar review of seismic design and detailing provisions of the Canadian Standard Association (CSA) Standard A23.3 on Design of Concrete Structures was also conducted for the same purpose. Six-storey and ten-storey prototype buildings were designed for Ottawa and Vancouver, using the seismic provisions of the 1965 National Building Code of Canada, representative of buildings in eastern and western Canadian. Preliminary static and dynamic linear elastic analyses were performed to assess the effectiveness of upgrading the ten-storey reinforced concrete building designed for Ottawa. The retrofit methods studied consisted of lateral bracing by adding reinforced concrete shear walls, diagonal steel braces, or diagonal steel cable strands. The results indicated that the retrofit techniques are effective in limiting deformations in non-ductile frame elements to
the elastic range. The numerical analyses were used to demonstrate the effectiveness of Buckling Restrained Braces (BRBs) as a retrofit method for seismically deficient reinforced concrete frame buildings. The experimental phase of research consisted of two, 2/3rd scale, single bay and single storey reinforced concrete frames, designed and constructed based on a prototype sixstorey moment resisting frame building located in Ottawa and Vancouver, following the
requirements of the 1965 edition of the NBCC. One test specimen served as a bare
control frame (BCF) that was first tested, repaired and retrofitted (RRF) to evaluate the effectiveness of the proposed retrofit methodology for buildings subjected to
earthquakes in the City of Ottawa. The control frame was assessed to be seismically
deficient. The second frame served as a companion non-damaged frame (RF) that was retrofitted with a similar retrofit concept but for buildings subjected to earthquakes in the City of Vancouver.
A new buckling restrained brace (BRB) was conceived and developed to retrofit existing sub-standard reinforced concrete frames against seismic actions. The new BRB consists of a ductile inner steel core and an outer circular sleeve that encompasses two circular steel sections of different diameters to provide lateral restraint against buckling in compression of inner steel core. Mortar is placed between the two circular sections to provide additional buckling resistance. The inner core is connected to novel end units that allow extension and contraction during tension-compression cycles under seismic loading while providing lateral restraint against buckling within the end zones. The end units constitute an original contribution to the design of Buckling Restrained Braces (BRBs), providing continuous lateral restraint along the core bar. The new technique has
been verified experimentally by testing four BRBs on the two test structures under
simulated seismic loading. The test results of the BRB retrofitted frames indicate
promising seismic performance, with substantial increases in the lateral load and
displacement ductility capacities by factors of up to 3.9 and 2.6, respectively. In addition, the test results demonstrate that the BRB technology can provide excellent drift control, increased stiffness, and significant energy dissipation, while the reinforced concrete frames continue fulfilling their function as gravity load carrying frames. The above development was further verified by an exhaustive analytical study using SAP2000. At the onset, analyses were conducted to calibrate and verify the analytical models. Two-dimensional, one-bay, one-storey models, simulating the BCF and RRF test frames, were created. The models were subjected to incrementally increasing lateral displacement reversals in nonlinear static pushover analyses, and the results were compared with those obtained in the test program. Material nonlinearity was modeled using “Links” to incorporate all lumped linear and nonlinear properties that were defined with moment-rotation properties for flexural frame members and with force-displacement properties for the diagonal buckling restrained braces. Comparison with test data demonstrated good agreement of the frame behaviour in the elastic and post-elastic ranges, and the loading and unloading stiffness. The research program was further augmented with nonlinear dynamic time history analyses to verify the feasibility of the new retrofit technique in multi-storey reinforced concrete frame buildings located in Canada and their performances relative to the performance-based design objectives stated in current codes. Prior to conducting the analyses, 450 artificial earthquake records were studied to select the best matches to the Uniform Hazard Spectra (UHS) according to the 2010 edition of the NBCC for Ottawa and Vancouver. Furthermore, additional analyses were conducted on buildings for the City of Ottawa based on amplified Uniform Hazard Spectrum compatible earthquake records. The nonlinear time-history response analyses were conducted using a model that permits inelasticity in both the frame elements and the BRBs.The results indicated that reinforced concrete buildings built before the 1970’s in the City of Ottawa do not require seismic retrofitting; they remain within the elastic range under current code-compatible earthquake records. The structural building performance is
within the Immediate Occupancy level, and all structural elements have capacities
greater than the force demands. In the City of Vancouver, buildings in their virgin state experienced maximum interstorey drifts of 2.3%, which is within the Collapse Prevention structural performance level. Improved building performance was realized by retrofitting the exterior frames with multiple uses of the BRB developed in this research project. The seismic shear demands were reduced in the columns, while limiting the deformations in the non-ductile frame elements to the elastic range. The lateral interstorey drift was limited to 0.92%, which lies within the Life Safety structural performance level.
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