Literatura académica sobre el tema "Bit (ordinateur)"
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Artículos de revistas sobre el tema "Bit (ordinateur)"
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Reverter, Antonio, Ron Okimoto, Robyn Sapp, Walter G. Bottje, Rachel Hawken y Nicholas J. Hudson. "Chicken muscle mitochondrial content appears co-ordinately regulated and is associated with performance phenotypes". Biology Open 6, n.º 1 (1 de diciembre de 2016): 50–58. http://dx.doi.org/10.1242/bio.022772.
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Walker, D. C. y J. Southgate. "The virtual cell--a candidate co-ordinator for 'middle-out' modelling of biological systems". Briefings in Bioinformatics 10, n.º 4 (17 de marzo de 2009): 450–61. http://dx.doi.org/10.1093/bib/bbp010.
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Srinivasan, T., K. Palanikumar y K. Rajagopal. "Roundness Error Evaluation in Drilling of Glass Fiber Reinforced Polypropylene (GFR/PP) Composites Using Box Behnken Design (BBD)". Applied Mechanics and Materials 766-767 (junio de 2015): 844–51. http://dx.doi.org/10.4028/www.scientific.net/amm.766-767.844.
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In this paper, the damage of drilling parameters on roundness error is investigated in drilling of Glass Fiber Reinforced Polypropylene (GFR/PP) matrix composites with ‘Brad and Spur’ drill bit. The experiment is carried out using Solid Carbide drill bit and L27 orthogonal array is used to analyze the effect of spindle speed, feed rate and drill diameter. A complete and in-detail evaluation and optimization of cutting parameter using Box-Behnken Design (BBD) technique is carried out. The design is contributed for quality and productivity equally and analysis of the drilling parameters. The roundness error is determined using response surface methodology (RSM) and Analysis of variance (ANOVA) which is used for analyzing the output results. One of the most important ovalty damage to be controlled on a cylindrical drilled part is the roundness error. The Co-ordinate Measuring Machine (CMM) is the general metrological equipment used for inspection of roundness error which is normally performed in a quality room. The results indicated that the model can be effectively used for predicting the response variable by means of which roundness error can be controlled. 3-D response surface graphs are developed to study the effect of drilling parameters with roundness error and presented in detail.
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Verma, Brijesh. "Recognition of Rotating Images Using an Automatic Feature Extraction Technique and Neural Networks". International Journal of Neural Systems 08, n.º 02 (abril de 1997): 201–7. http://dx.doi.org/10.1142/s0129065797000215.
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This paper presents a new automatic feature extraction technique and a neural network based classification method for recognition of rotating images. The image processing technique extracts global features of an image and converts a large size image into a one-dimensional small vector. A special advantage of the proposed technique is that the extracted features are the same even if the original image is rotated with rotation angles from 5 to 355 or rotated and a little bit distorted. The proposed approach technique is based on simple co-ordinate geometry, fuzzy sets and neural networks. The proposed approach is very easy in implementation and its has been developed in C++ on a Sun workstation. The experimental results have demonstrated that the proposed approach performs successfully on a variety of small as well as large scale rotated and distorted images.
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Martin, I., M. Giralt, O. Viñas, R. Iglesias, T. Mampel y F. Villarroya. "Co-ordinate decrease in the expression of the mitochondrial genome and nuclear genes for mitochondrial proteins in the lactation-induced mitochondrial hypotrophy of rat brown fat". Biochemical Journal 308, n.º 3 (15 de junio de 1995): 749–52. http://dx.doi.org/10.1042/bj3080749.
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The relative abundance of the mitochondrial-encoded mRNAs for cytochrome c oxidase subunit II and NADH dehydrogenase subunit I was lower in brown adipose tissue (BAT) from lactating rats than in virgin controls. This decrease was in parallel with a significant decrease in mitochondrial 16 S rRNA levels and in the relative content of mitochondrial DNA in the tissue. BAT from lactating rats showed lowered mRNA expression of the nuclear-encoded genes for the mitochondrial uncoupling protein, subunit IV of cytochrome c oxidase and the adenine nucleotide translocase isoforms ANT1 and ANT2, whereas mRNA levels for the ATP synthase beta-subunit were unchanged. However, the relative content of this last protein was lower in BAT mitochondria from lactating rats than in virgin controls. It is concluded that lactation-induced mitochondrial hypotrophy in BAT is associated with a co-ordinate decrease in the expression of the mitochondrial genome and nuclear genes for mitochondrial proteins. This decrease is caused by regulatory events acting at different levels, including pre- and post-transcriptional regulation. BAT appears to be a useful model with which to investigate the molecular mechanisms involved in the co-ordination of the expression of the mitochondrial and nuclear genomes during mitochondrial biogenesis.
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Yi, Danielle, Hai P. Nguyen y Hei Sook Sul. "Epigenetic dynamics of the thermogenic gene program of adipocytes". Biochemical Journal 477, n.º 6 (27 de marzo de 2020): 1137–48. http://dx.doi.org/10.1042/bcj20190599.
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Brown adipose tissue (BAT) is a metabolically beneficial organ capable of burning fat by dissipating chemical energy into heat, thereby increasing energy expenditure. Moreover, subcutaneous white adipose tissue can undergo so-called browning/beiging. The recent recognition of the presence of brown or beige adipocytes in human adults has attracted much attention to elucidate the molecular mechanism underlying the thermogenic adipose program. Many key transcriptional regulators critical for the thermogenic gene program centering on activating the UCP1 promoter, have been discovered. Thermogenic gene expression in brown adipocytes rely on co-ordinated actions of a multitude of transcription factors, including EBF2, PPARγ, Zfp516 and Zc3h10. These transcription factors probably integrate into a cohesive network for BAT gene program. Moreover, these transcription factors recruit epigenetic factors, such as LSD1 and MLL3/4, for specific histone signatures to establish the favorable chromatin landscape. In this review, we discuss advances made in understanding the molecular mechanism underlying the thermogenic gene program, particularly epigenetic regulation.
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Desai, Nivedita S. y Dr Shilpa DR. "Dual mode Bluetooth Controller via PCM-CODEC Interface for Audio Application". Journal of University of Shanghai for Science and Technology 23, n.º 06 (18 de junio de 2021): 775–83. http://dx.doi.org/10.51201/jusst/21/05351.
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Bluetooth may be an inaccessible development standard utilized for exchanging data between settled and flexible contraptions over brief divisions utilizing UHF radio waves within the mechanical, coherent, and restorative radio bunches, from 2.402GHz to 2.480 GHz. PCM codec is an A/D interface for speech signals. The Bluetooth center framework underpins co-ordinate transport of application information that’s isochronous and of a consistent rate (either bit-rate or frame-rate for pre-framed information) employing an SCO or ESCO consistent joins. These coherent joins save physical channel transfer speed and give a consistent rate of transport bolted to the piconet clock. The codec interface block is used to interface an external PCM (8KHz voice data) or a stereo codec with the baseband controller for the direct transfer of voice data on isochronous links to external CODEC. Bluetooth baseband supports two CODEC interface protocols 1) for audio links it is the PCM interface and 2) for mono/stereo music data from audio codec it uses the IIS interface. This enables the source of isochronous data to be directly interfaced to the baseband controller if it is not required to be processed by firmware. It also provides the host access path where the source of isochronous data will be any application running on the host and data is written and read directly into baseband SCO/ESCO FIFOs from firmware. In this paper, PCM is verified in the Cadence tool and simulated images are shown.
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Sia, Surendra Kumar y Pravakar Duari. "Agentic work behaviour and thriving at work: role of decision making authority". Benchmarking: An International Journal 25, n.º 8 (29 de noviembre de 2018): 3225–37. http://dx.doi.org/10.1108/bij-07-2017-0204.
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PurposeThe purpose of this paper is to examine the contribution of agentic work behaviour and decision-making authority (DMA) to thriving at work and, more importantly, the moderating role of DMA in the relationship between agentic behaviour and thriving.Design/methodology/approachThe study has been carried out upon a random sample of 330 employees below supervisory level from manufacturing companies located at Odisha (a state located at the eastern part of India). After verifying the significance of correlation among the study variables through Pearson’s product moment correlation, moderated regression analyses were carried out to examine the independent contribution of agentic work behaviour and DMA to thriving as well as the moderating contribution of DMA towards thriving.FindingsResults reveal that the three dimensions of agentic work behaviour, namely, task focus, exploration and heedful relation, have a direct positive contribution towards thriving at workplace. As far as the moderation is concerned, it is observed that the thriving level is higher for the employees having high DMA irrespective of the level of agentic work behaviour at each dimension.Research limitations/implicationsThe findings imply for designing interventions to enhance task focus, super-ordinate relationship and interest for learning. In addition, the organisations should provide autonomy to employees for decision making.Originality/valueThe study is first of its kind in the Indian context upon employee thriving. In this study, the authors have not only investigated the separate independent contribution of agentic behaviour and DMA, but also their interacting contribution to employee thriving.
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Rao, K. Koteswara y B. Nagamani Naidu. "Mechanism of Luminescence Enhancement in Eu3+ Activated Double Perovskite Phosphors Bi2-xEuxWO6 (x = 0-0.24) Prepared by Sol-Gel Method". Asian Journal of Chemistry 34, n.º 9 (2022): 2205–10. http://dx.doi.org/10.14233/ajchem.2022.23765.
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A double perovskite structured series Bi2–xEuxWO6 (x = 0.03-0.24) was prepared by using simple citrate sol-gel method at 700 ºC for 5 h of sintering. The double perovskite structure and its lattice parameters were analyzed by the XRD technique and found to be pure orthorhombic phase. The concentrated sample of x = 0.12 exhibits more intensity than all other concentration in their emission spectra. Particle size, thickness of the particle, distance between particles and its surface morphology were identified by scanning electron microscopy. The size and distance between particles lies in between the range of 1-50 nm and 20-50 nm, respectively. In addition to this the absorption of light capacity for every sample was investigated through diffuse reflectance spectra method. All the samples of double perovskite structures exhibit a sharp cut-off of absorption light in the UV and visible regions of diffuse reflectance spectra. Predominantly, sample x = 0.12 shows very good charge transfer band in their excitation spectra that leads to more absorption of light correspondingly emits high intensity in emission spectra. All the samples of series emit main peaks in the range of 550-700 nm in their emission spectra. Out of all four main peaks, 614 nm peak represents the red phosphor with 5D0−7F2 transition in the emission spectra. The prepared double perovskite structure compound CRI co-ordinates (0.6254, 0. 3739) are almost close to commercially available red phosphor i.e. Y2O2S (0.67, 0.33) as per NTSC. Hence, the prepared red phosphors can be used in order to display devices, luminescent materials and WLEDs.
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El Kaim Billah, Rachid, Moonis Ali Khan, Saikh Mohammad Wabaidur, Byong-Hun Jeon, Amira AM, Hicham Majdoubi, Younesse Haddaji, Mahfoud Agunaou y Abdessadik Soufiane. "Chitosan/Phosphate Rock-Derived Natural Polymeric Composite to Sequester Divalent Copper Ions from Water". Nanomaterials 11, n.º 8 (9 de agosto de 2021): 2028. http://dx.doi.org/10.3390/nano11082028.
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Herein, a chitosan (CH) and fluroapatite (TNP) based CH-TNP composite was synthesized by utilizing seafood waste and phosphate rock and was tested for divalent copper (Cu(II)) adsorptive removal from water. The XRD and FT-IR data affirmed the formation of a CH-TNP composite, while BET analysis showed that the surface area of the CH-TNP composite (35.5 m2/g) was twice that of CH (16.7 m2/g). Mechanistically, electrostatic, van der Waals, and co-ordinate interactions were primarily responsible for the binding of Cu(II) with the CH-TNP composite. The maximum Cu(II) uptake of both CH and CH-TNP composite was recorded in the pH range 3–4. Monolayer Cu(II) coverage over both CH and CH-TNP surfaces was confirmed by the fitting of adsorption data to a Langmuir isotherm model. The chemical nature of the adsorption process was confirmed by the fitting of a pseudo-second-order kinetic model to adsorption data. About 82% of Cu(II) from saturated CH-TNP was recovered by 0.5 M NaOH. A significant drop in Cu(II) uptake was observed after four consecutive regeneration cycles. The co-existing ions (in binary and ternary systems) significantly reduced the Cu(II) removal efficacy of CH-TNP.
Tesis sobre el tema "Bit (ordinateur)"
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Preda, Marius. "Système d'animation d'objets virtuels". Phd thesis, Paris 5, 2002. http://www.theses.fr/2002PA05S019.
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Dans le cadre de la nouvelle société de l'information multimédia et communicante, cette thèse propose des contributions méthodologiques et techniques relatives à la représentation, l'animation et la transmission des objets virtuels. Les méthodes existantes sont analysées de façon comparées et les performances des standards multimédias actuels évaluées en termes de réalisme d'animation et de débit de transmission. Pour surmonter les limitations mises en évidence, un nouveau cadre de modélisation et d'animation de personnages virtuels est proposé. .Within the framework of the emerging networked multimedia information society, this dissertation brings forward methodological and technical contributions for representing, animating and transmitting 3D virtual objects. The existing methods are first analyzed and compared, and the performances of current multimedia standards are evaluated in terms of animation realism and transmission bitrate. .
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Thiele, Stefan. "Read-out and coherent manipulation of an isolated nuclear spin using a single-molecule magnet spin-transistor". Phd thesis, Université de Grenoble, 2014. http://tel.archives-ouvertes.fr/tel-00984973.
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La réalisation d'un ordinateur quantique fonctionnel est l'un des objectifs tech- nologiques les plus ambitieux pour les scientifiques d'aujourd'hui. Sa brique de base est composée d'un système quantique à deux niveaux, appelé bit quantique (ou qubit). Parmi les différents concepts existants, les dispositifs à base de spin sont très attractifs car ils bénéficient de la progression constante des techniques de nanofabrication et permettent la lecture électrique de l'état du qubit. Dans ce contexte, les dispositifs à base de spins nucléaires offrent un temps de cohérence supérieur à celui des dispositifs à base de spin electronique en raison de leur meilleure isolation à l'environnement. Mais ce couplage faible a un prix: la détection et la manipulation des spins nucléaires individuels restent des tâches difficiles. De très bonnes conditions expérimentales étaient donc essentielles pour la réussite de ce projet. Outre des systèmes de filtrage des radiofréquences à très basses températures et des amplificateurs à très faible bruit, j'ai développé de nouveaux supports d'échantillons et des bobines de champ magnétique trois axes compacts avec l'appui des services techniques de l'Institut Néel. Chaque partie a été optimisée afin d'améliorer la qualité de l'installation et évaluée de manière quantitative. Le dispositif lui-même, un qubit réalisé grâce à un transistor de spin nucléaire, est composé d'un aimant à molécule unique couplé à des électrodes source, drain et grille. Il nous a permis de réaliser la lecture électrique de l'état d'un spin nucléaire unique, par un processus de mesure non destructif de son état quantique. Par conséquent, en sondant les états quantique de spin plus rapidement que le temps de relaxation caractéristique de celui-ci, nous avons réalisé la mesure de la trajectoire quantique d'un qubit nucléaire isolé. Cette expérience a mis en lumière le temps de relaxation T1 du spin nucléaire ainsi que son mécanisme de relaxation dominant. La manipulation cohérente du spin nucléaire a été réalisée en utilisant des champs électriques externes au lieu d'un champ magnétique. Cette idée originale a plusieurs avantages. Outre une réduction considérable du chauffage par effet Joule, les champs électriques permettent de contrôler et de manipuler le spin unique de façon très rapide. Cependant, pour coupler le spin à un champ électrique, un processus intermédiaire est nécessaire. Un tel procédé est l'interaction hyperfine, qui, si elle est modifiée par un champ électrique, est également désigné sous le nom d'effet Stark hyperfin. En utilisant cet effet, nous avons mis en évidence la manipulation cohérente d'un spin nucléaire unique et déterminé le temps de cohérence T2 . En outre, l'exploitation de l'effet Stark hyperfin statique nous avons permis de régler le qubit de spin nucléaire à et hors résonance par l'intermédiaire de la tension de grille. Cela pourrait être utilisé pour établir le contrôle de l'intrication entre les différents qubits nucléaires. En résumé, nous avons démontré pour la première fois la possibilité de réaliser et de manipuler un bit quantique basé sur un aimant à molécule unique, étendant ainsi le potentiel de la spintronique moléculaire au delà du stockage de données classique. De plus, la grande polyvalence des molécules aimants est très prometteuse pour une variété d'applications futures qui, peut-être un jour, parviendront à la réalisation d'un ordinateur quantique moléculaire.
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Li, Fangyan. "Simulation multi-moteurs multi-niveaux pour la validation des spécifications système et optimisation de la consommation". Thesis, Nice, 2016. http://www.theses.fr/2016NICE4008/document.
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Ce travail vise la modélisation au niveau système, en langage SystemC-AMS, et la simulation d'un émetteur-récepteur au standard Bluetooth Low Energy (BLE). L'objectif est d'analyser la relation entre les performances, en termes de BER et la consommation d'énergie du transceiver. Le temps de simulation d’un tel système, à partir de cas d’étude (use case) réaliste, est un facteur clé pour le développement d’une telle plateforme. De plus, afin d’obtenir des résultats de simulation le plus précis possible, les modèles « haut niveau » doivent être raffinés à partir de modèles plus bas niveau où de mesure. L'approche dite Meet-in-the-Middle, associée à la méthode de modélisation équivalente en Bande Base (BBE, BaseBand Equivalent), a été choisie pour atteindre les deux conditions requises, à savoir temps de simulation « faible » et précision des résultats. Une simulation globale d'un système de BLE est obtenue en intégrant le modèle de l'émetteur-récepteur dans une plateforme existante développée en SystemC-TLM. La simulation est basée sur un système de communication de deux dispositifs BLE, en utilisant différents scénarios (différents cas d'utilisation de BLE). Dans un premier temps nous avons modélisé et validé chaque bloc d’un transceiver BT. Devant le temps de simulation prohibitif, les blocs RF sont réécrits en utilisant la méthodologie BB, puis raffinés afin de prendre en compte les non-linéarités qui vont impacter le couple consommation, BER. Chaque circuit (chaque modèle) est vérifié séparément, puis une première simulation système (point à point entre un émetteur et un récepteur) est effectuéeThis work aims at system-level modelling a defined transceiver for Bluetooth Low energy (BLE) system using SystemC-AMS. The goal is to analyze the relationship between the transceiver performance and the accurate energy consumption. This requires the transceiver model contains system-level simulation speed and the low-level design block power consumption and other RF specifications. The Meet-in-the-Middle approach and the Baseband Equivalent method are chosen to achieve the two requirements above. A global simulation of a complete BLE system is achieved by integrating the transceiver model into a SystemC-TLM described BLE system model which contains the higher-than-PHY levels. The simulation is based on a two BLE devices communication system and is run with different BLE use cases. The transceiver Bit-Error-Rate and the energy estimation are obtained at the end of the simulation. First, we modelled and validated each block of a BT transceiver. In front of the prohibitive simulation time, the RF blocks are rewritten by using the BBE methodology, and then refined in order to take into account the non-linearities, which are going to impact the couple consumption, BER. Each circuit (each model) is separately verified, and then a first BLE system simulation (point-to-point between a transmitter and a receiver) has been executed. Finally, the BER is finally estimated. This platform fulfills our expectations, the simulation time is suitable and the results have been validated with the circuit measurement offered by Riviera Waves Company. Finally, two versions of the same transceiver architecture are modelled, simulated and compared
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Melul, Franck. "Développement d'une nouvelle génération de point mémoire de type EEPROM pour les applications à forte densité d'intégration". Electronic Thesis or Diss., Aix-Marseille, 2022. http://www.theses.fr/2022AIXM0266.
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L’objectif de ces travaux de thèse a été de développer une nouvelle génération de point mémoire de type EEPROM pour les applications à haute fiabilité et à haute densité d’intégration. Dans un premier temps, une cellule mémoire très innovante développée par STMicroelectronics – eSTM (mémoire à stockage de charges de type Splitgate avec transistor de sélection vertical enterré) – a été étudiée comme cellule de référence. Dans une deuxième partie, dans un souci d’améliorer la fiabilité de la cellule eSTM et de permettre une miniaturisation plus agressive de la cellule EEPROM, une nouvelle architecture mémoire a été proposée : la cellule BitErasable. Elle a montré une excellente fiabilité et a permis d’apporter des éléments de compréhension sur les mécanismes de dégradation présents dans ces dispositifs mémoires à transistor de sélection enterré. Cette nouvelle architecture offre de plus la possibilité d’effacer les cellules d’un plan mémoire de façon individuelle : bit à bit. Conscient du grand intérêt que présente l’effacement bit à bit, un nouveau mécanisme d’effacement pour injection de trous chauds a été proposé pour la cellule eSTM. Il a montré des performances et un niveau de fiabilité parfaitement compatible avec les exigences industrielles des applications Flash-NORThe objective of this thesis was to develop a new generation of EEPROM memory for high reliability and high density applications. First, an innovative memory cell developed by STMicroelectronics - eSTM (Split-gate charge storage memory with buried vertical selection transistor) - was studied as a reference cell. In a second part, to improve the reliability of the eSTM cell and to allow a more aggressive miniaturization of the EEPROM cell, a new memory architecture has been proposed: the BitErasable cell. It showed an excellent reliability and allowed to bring elements of under-standing on the degradation mechanisms present in these memory devices with buried selection transistor. This new architecture also offers the possibility to individually erase cells in a memory array: bit by bit. Aware of the great interest of bit-by-bit erasing, a new erasing mechanism by hot hole injection has been proposed for the eSTM cell. It has shown performances and a level of reliability perfectly compatible with the industrial requirements of Flash-NOR applications
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Petit, Sophie. "Étude des méthodes de prédiction de taux d'erreurs en orbite dans les mémoires : nouvelle approche empirique". Toulouse, ENSAE, 2006. http://www.theses.fr/2006ESAE0015.
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Le phénomène de Single Event Upset (SEU) correspond au basculement logique d'un point mémoire suite au passage d'une particule énergétique. Les composants de type SRAM et DRAM, soumis à l'environnement spatial, sont sensibles aux SEU, il est alors primordial de prévoir leur sensibilité avant de les intégrer dans les missions spatiales. L'enjeu actuel est de concevoir un modèle de prédiction fiable utilisable pour tout type de mémoire, même fortement intégrée. La première phase de ce travail est une analyse des retours d'expériences embarquées qui a permis d'évaluer les modèles de prédiction standard, basés sur la modélisation IRPP, en comparant directement les taux d'erreurs en vol aux taux prédits, et démontrant leur incapacité à fournir des prédictions correctes. L'analyse des sources d'erreurs possibles a montré la difficulté d'améliorer les modèles standard, nous amenant alors à proposer une tout autre technique de prédiction. Ainsi, la méthode de prédiction empirique, basée sur la sensibilité mesurée des composants aux SEU, pour plusieurs angles d'incidence des particules, est présentée et mise en œuvre sur un ensemble de composants ; elle donne des résultats très encourageants. Une étude des événements multiples a été menée : elle montre que la diffusion des porteurs est à prendre en compte dans la modélisation des mécanismes de collection de charge mis en jeu. Enfin, des simulations numériques 3D couplées à des modèles analytiques simples permettent l'étude quantitative des mécanismes de collection dans une des structures ayant volé : ces outils ont confirmé le rôle majeur de la diffusion dans les SEU.
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Marcireau, Alexandre. "Vision par ordinateur évènementielle couleur : cadriciel, prototype et applications". Thesis, Sorbonne université, 2019. http://www.theses.fr/2019SORUS248.
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L'ingénierie neuromorphique aborde de manière bio-inspirée le design des capteurs et ordinateurs. Elle prône l'imitation du vivant à l'échelle du transistor, afin de rivaliser avec la robustesse et la faible consommation des systèmes biologiques. Les caméras évènementielles ont vu le jour dans ce cadre. Elles possèdent des pixels indépendants qui détectent de manière asynchrone les changements dans leur champ visuel, avec une grande précision temporelle. Ces propriétés étant mal exploitées par les algorithmes usuels de vision par ordinateur, un nouveau paradigme encourageant de petits calculs à chaque évènement a été développé. Cette approche témoigne d'un potentiel à la fois pour la vision par ordinateur et en tant que modèle biologique. Cette thèse explore la vision par ordinateur évènementielle, afin de mieux comprendre notre système visuel et identifier des applications. Nous approchons le problème par la couleur, un aspect peu exploré des capteurs évènementiels. Nous présentons un cadriciel supportant les évènements couleur, ainsi que deux dispositifs expérimentaux l'utilisant : une caméra couleur évènementielle et un système pour la psychophysique visuelle destiné à l'étude du temps précis dans le cerveau. Nous considérons l'application du capteur couleur à la méthode de génie génétique Brainbow, et présentons un modèle mathématique de cette dernièreNeuromorphic engineering is a bio-inspired approach to sensors and computers design. It aims to mimic biological systems down to the transistor level, to match their unparalleled robustness and power efficiency. In this context, event-based vision sensors have been developed. Unlike conventional cameras, they feature independent pixels which asynchronously generate an output upon detecting changes in their field of view, with high temporal precision. These properties are not leveraged by conventional computer vision algorithms, thus a new paradigm has been devised. It advocates short calculations performed on each event to mimic the brain, and shows promise both for computer vision and as a model of biological vision. This thesis explores event-based computer vision to improve our understanding of visual perception and identify potential applications. We approach the issue through color, a mostly unexplored aspect of event-based sensors. We introduce a framework supporting color events, as well as two experimental devices leveraging it: a three-chip event-based camera performing absolute color measurements, and a visual psychophysics setup to study the role of precise-timing in the brain. We explore the possibility to apply the color sensor to the genetic engineering Brainbow method, and present a new mathematical model for the latter
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Terrissa, Saddek Labib. "Vision bio-fondée appliquée à l'analyse d'images". Le Havre, 2006. http://www.theses.fr/2006LEHA0001.
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La reconnaissance de l'environnement par un être vivant passe forcément par la rétine. Cette partie du système nerveux central réalise beaucoup de traitements et notamment la détection du mouvement et l'extraction des caractéristiques dynamiques d'une scène. Ces aspects n'ont pas atteint le niveau de développement que les traitements statiques en vision artificielle. C'est pourquoi, compte tenu de son intérêt, nous avons contribué à l'élaboration d'un prototype générique de rétine artificielle d'inspiration biologique que nous avons appelé Rétina. Il est fondé sur un réseau de neurones artificiels, organisé de manière à simuler la variation radiale de l'acuité visuelle (vision fovéale). La mise en œuvre de neurones analogiques et impulsionnels nous a permis d'encoder les informations. A partir des signaux impulsionnels issus de la Rétina, nous avons analyser et détecter la variation des niveaux de gris dans des images dynamiques. Ensuite, nous avons effectué une reconstitution de ces images en utilisant des techniques des réseaux de neurones et de traitement de signalThe environment recognition goes inevitably through the retina of alive beings. This component is a part of the central nervous system witch performs many processing, especially in motion detection and features extraction of a scene. These aspects are not reach the development level compared with static processing in artificial vision. For these reasons, we are developed a generic prototype of artificial retina inspired from biology witch we are titled Retina. This system is based on artificial neural network organised to simulate the radial variation of the acuity. The information is encoded through the implementation of analogue and impulse neurons. These retinal signal impulses are analysed in order to detect the variation of grey level in dynamic images. Moreover, we reconstitute these images using neural networks techniques and signal processing
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Debaecker, Thibaud. "Geometric and bio-inspired analysis of non-linear image sensors". Paris 6, 2010. http://www.theses.fr/2010PA066717.
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Alors que l'image sous toutes ses formes s'est désormais imposée dans la vie quotidienne de chacun d'entre nous, les capteurs d'images sortant du classique modèle perspectif à point de vue unique se banalisent jusqu'à devenir les pièces maîtresses de nombreux produits de hautes technologies, à destination d'industries comme du grand public. Qu'ils soient bio-inspirés, se rapprochant des rétines artificielles ou à large champs de vue, grâce à des lentilles ou à des miroirs, l'utilisation des images acquises pas ces appareils nécessitent des modèles qui, jusqu'à présent, ont été construits comme des généralisations des modèles pré-existants et considèrent qu'un capteur d'images réalise un mapping d'un monde en trois dimensions vers une image plane, reliant chaque point de l'image par un rayon à son antécédent dans l'espace. Tous ces capteurs souffrent pourtant de résolutions variables telles, que l'approximation du champ de vue du pixel comme un rayon de lumière pose de réels problèmes dans leur utilisation. Cette thèse présente une triple approche pour la caractérisation de ces capteurs, la première inspirée de l'architecture biologique de la rétine, la seconde est un modèle générique de caméra utilisant les Algèbres Géométriques et une méthode qui en permet le calibrage, quelque soit le type de caméra employé, et la troisième montre que considérer ces ouvertures angulaires pour chaque pixel d'un point de vue projectif permet de retrouver certaines caractéristiques du capteur, de s'affranchir des distortions optiques, et enfin d'obtenir des images après remapping, correspondant à celles qui auraient été prises si le capteur avait été parfaitement perspectif
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Leclercq, Edouard. "Vision artificielle par modules bio-fondés spécifiques : forme et mouvement". Le Havre, 1999. http://www.theses.fr/1999LEHA0001.
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Ce rapport concerne un système de vision artificielle par modules inspires du modèle de vision biologique. Les fonctions de ce système sont ciblées sur la détection de forme et du mouvement d'objets dits synthétiques au sein d'une séquence d'images. Ce système fait appel à des notions de neurocybernétique, c'est-a-dire des notions de neurophysiologie de l'œil couplées à l'informatique. La rétine constitue la référence de base du modèle présenté. Certaines caractéristiques de ce capteur ainsi qu'un type de cellule du cortex visuel primaire sont une source d'inspiration. Deux aspects sont à retenir, l'aspect structurel et l'aspect fonctionnel du modèle. Concernant le premier aspect, le modèle est base sur la notion de pyramide gaussienne permettant de reproduire le principe de multi résolutions. Ce principe est utilisé afin de reproduire la variation d'acuité au sein de la rétine et de modéliser les champs réceptifs des cellules rétiniennes impliquées. Quant à cette structure, de nouveaux filtres performants ont été implémentés. L'aspect fonctionnel présente une architecture hiérarchisée compose de cinq niveaux qui remplissent chacun une fonction spécifique, de l'acquisition d'image jusqu'à l'intégration du mouvement en passant par l'extraction de contours, l'extraction de verticales et la détermination du sens du mouvement. Ces différents niveaux sont constitués de cellules spécifiques inspirées de celles de la rétine et du cortex. Une application relative au suivi d'objet mobile à l'aide d'un globe oculaire est développée. Cette application met en oeuvre la partie traitement du modèle présenté, partie implémentée sur un réseau de transputers T805 suivant une architecture SIMD. Les résultats concernant la détection d'objet ainsi que la détermination du mouvement sont obtenus a l'aide des cellules spécifiques.
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Lee, Yu Chung Eugene. "Co-ordinated supply chain management and optimal control problems". online access from Digital Dissertation Consortium, 2007. http://libweb.cityu.edu.hk/cgi-bin/er/db/ddcdiss.pl?3299869.
Texto completoLibros sobre el tema "Bit (ordinateur)"
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Joanneum), Landesbildergalerie (Steiermärkisches Landesmuseum y Zentrum für Kunst und Medientechnologie Karlsruhe, eds. A little known story about a movement, a magazine and the computer's arrival in art: New Tendencies and Bit international, 1961-1973. Karlsruhe, Germany: ZKM/Center for Art and Media, 2011.
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Jennifer, Fulton y Guilford Ed, eds. The big basics book of PCs. 2a ed. Indianapolis, Ind: Que, 1997.
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Avtar Singh, 1947 June 2-, ed. 16-bit microprocessors: Architecture, software, and interface techniques. Englewood Cliffs, N.J: Prentice-Hall, 1985.
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BIM demystified: An architect's guide to Building Information Modelling/Management (BIM). 2a ed. London: Riba Publishing, 2013.
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Bim demystified: An architect's guide to Building Information Modelling/Management (BIM). London: Riba Publishing, 2012.
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Big Blue: IBM's use and abuse of power. New York: Dodd, Mead, 1986.
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Ron, Unger, ed. Biological computation. Boca Raton: Chapman & Hall/CRC, 2010.
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Thai, Kim-Loan. Architecture des re seaux haut de bit: Cours, exercices et corrige s. Paris: Herme s, 1995.
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Carr, Nicholas G. The big switch: Rewiring the world, from Edison to Google. New York: W. W. Norton & Co., 2008.
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Cotoneschi, Patrizia y Giancarlo Pepeu, eds. Raccomandazioni per lo sviluppo dell'Editoria Elettronica negli Atenei Italiani. Florence: Firenze University Press, 2006. http://dx.doi.org/10.36253/978-88-6453-154-0.
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In May 2004, the delegates of the Library Commission of the CRuI had already identified the issue of electronic publishing as one of the strategic aspects to be addressed and explored with the utmost attention. The setting up of the working group on Electronic Publishing, co-ordinated by the University of Florence, formalised this interest, stimulating the analysis of the state of the art in this field in Italy, the opportunities which it offered to the academic world and the definition of possible lines of development. The "Recommendations" comprised in this publication are addressed to the delegates of the Chancellors of the Italian universities and their collaborators, and intended to provide information and suggestions for the development of electronic publishing initiatives. They are consequently designed not only as a tool for help and guidance for those who are already moving in the direction of a University publishing initiative, but also as an invitation to reflect on the importance that electronic publishing is acquiring for the teaching and scientific activities of the future.
Capítulos de libros sobre el tema "Bit (ordinateur)"
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Pearman, N. M. "Areawide Ricefield Rat Control by Small Scale Landowners in S.E. Asia through the Co-ordinated Application of Flocoumafen Block Bait". En Pest Management in Rice, 430–39. Dordrecht: Springer Netherlands, 1990. http://dx.doi.org/10.1007/978-94-009-0775-1_35.
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Lewis, Geoffrey. "Conjunctions and Particles". En Turkish Grammar, 205–18. Oxford University PressOxford, 2000. http://dx.doi.org/10.1093/oso/9780198700364.003.0013.
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Abstract ve [A] ‘and’ is little used in speech and many Turks contrive to dispense with it entirely in writing, employing the native resources of the language instead: ile, -ip, de (see next section), or simple juxtaposition. That is to say, co-ordinate words and clauses may be put one after the other with no conjunction at all, on the pattern of Caesar’s veni vidi vici. Thus ‘he came into the room and sat down on a chair’ may be odaya girdi ve bir sandalyeye oturdu or odaya girip bir sandalyeye oturdu or odaya girdi, bir sandalyeye oturdu. ‘You and I’ may be sen ve ben or seninle ben. ‘You, I, and your brother’ may be sen, ben, ve kardeŞin or sen, ben, kardeŞin de or just sen, ben, kardeŞin.
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Brewer, Bill. "Introduction: Action". En Spatial Representation, 271–76. Oxford University PressOxford, 1999. http://dx.doi.org/10.1093/oso/9780198238874.003.0016.
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Abstract Two problems are discussed under the head of’ Action’. The first concerns the connection between the spatial representations involved in perception and action. How does perception control and co-ordinate basic spatial action? More precisely, what can we say about the relation between the ways in which spatial information is coded in perception and in the organization of spatial behaviour, given the nature of perceptuo-motor control? The second problem concerns the nature of action itself, as the directed dioing of something by an agent, as opposed to certain bits of animals’ bodies moving in various ways.
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Kumar, Sumit. "Modeling of Laser-Irradiated Biological Tissue". En Terahertz, Ultrafast Lasers and Their Medical and Industrial Applications. IntechOpen, 2022. http://dx.doi.org/10.5772/intechopen.106794.
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The laser has been widely used in medical fields. One application of the laser is laser-based photo-thermal therapy, wherein the short-pulsed laser is generally used to destroy the cancerous cells. The efficacy of the laser-based photo-thermal therapy can be improved if we minimize the thermal damage to the surrounding healthy tissue. So, it is essential to understand the laser-tissue interaction and thermal behavior of biological tissue during laser-based photo-thermal therapy. The light propagation through the biological tissue is generally mathematically modeled by the radiative heat transfer equation (RTE). The RTE has been solved using the discrete ordinate method (DOM) to determine the intensity inside the laser-irradiated biological tissue. Consequently, the absorbed photon energy act as the source term in the Fourier/non-Fourier model-based bio-heat transfer equation to determine the temperature distribution inside the biological tissue subjected to short-pulse laser irradiation. The non-Fourier model-based bio-heat transfer equation is numerically solved using the finite volume method (FVM). The numerical results have been compared with the analytical results obtained using the finite integral transform (FIT) technique. A comparative study between the Fourier and non-Fourier heat conduction models has also been carried out.
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Yes, Elaine M. Bail, Paul C. Guest, y John C. Hutton. "Insulin synthesis". En Insulin: Molecular Biology to Pathology, 64–92. Oxford University PressOxford, 1992. http://dx.doi.org/10.1093/oso/9780199632299.003.0003.
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Abstract The structure of insulin has been highly conserved throughout higher vertebrate evolution. The hormone consists of an A-chain (21 amino acids) and a B-chain (30 amino acids), connected by two intermolecular disulphide bonds (A7-B7, A20-Bl9), with an intramolecular bond between A6 and All. Invariant features include the positions of the three disulphide bonds, the N- and C-terminal regions of the A-chain, and the hydrophobic residues in the C-terminal region of the B-chain. In the presence of zinc, at acid pH, most insulins form crystals composed of insulin hexamers. The hexamer consists of three dimers arranged roughly in a plane. The central axis perpendicular to the plane passes through two zinc ions; each is co-ordinated with the imidazole groups of three BIO histidine residues with one located above and one below the plane of the hexamer. The insulin dimers are held together in the crystal by hydrogen bonds between amino acid B24 and amino acid B26, forming an antiparallel 13-pleated sheet structure (Steiner et al. 1989).
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Neofitou, P., D. Drikakis y M. A. Leschziner. "Study of Newtonian and Non-Newtonian Fluid Flow in a Channel with a Moving Indentation". En Cardiovascular Flow Modelling and Measurement with Application to Clinical Medicine, 39–47. Oxford University PressOxford, 1999. http://dx.doi.org/10.1093/oso/9780198505204.003.0004.
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Abstract In the context of bio-fluid mechanics, the study of unsteady flow in channels with moving boundaries is largely motivated by the need to understand biological flows in collapsible tubes such as arteries and veins. Since in vivo arterial flows involve many physical issues which need to be modelled, simpler geometrical models are usually employed which, however, reproduce many of the important phenomena occuring in the real flow, such as unsteadiness, moving walls, separation and propagation of vorticity waves. Such a model is the flow in a channel with a moving indentation in one wall [1, 2]. Pedley and his co-workers have in the past studied, both experimentally and computationally, the flow down stream of a laterally moving indentation focusing especially on the generation and propagation of wave crests. The above flow was considered in the present study as a basis for validating our numerical model which is based on the Navier-Stokes equations in generalised curvilinear co-ordinates in conjunction with the space conservation law for the case of moving, compressing grids.
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Barron, Andrew R. "Aryloxide-aluminium π-bonding in the π-face selectivity of co-ordinated ketones towards nucleophilic attack". En Organic Crystal Chemistry, 164–70. Oxford University PressOxford, 1991. http://dx.doi.org/10.1093/oso/9780198553830.003.0012.
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Abstract One of the most important c-c bond formation reactions in organic synthesis is nucleophilic addition to organo-carbonyl groups. A significant development in this area has been the use of the bulky organoaluminum compound, A1Me(BHT)2 (1), for controlling the -face selectivity of carbonyl moieties towards nucleophilic addition (Maruoka, Itoh, Yamamoto, 1985; Maruoka, Itoh, Sakuria, Yamamoto, 1988).
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Jani, Raxit Girishkumar, Ramesh T. Prajapati y Anilkumar C. Suthar. "Air Miner". En Handbook of Research on Lifestyle Sustainability and Management Solutions Using AI, Big Data Analytics, and Visualization, 254–73. IGI Global, 2022. http://dx.doi.org/10.4018/978-1-7998-8786-7.ch016.
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Air miner gathers live data about the carbon monoxide indoors. It significantly reduces the chances of residents contracting respiratory disorder owing to its proactive alert systems. It utilizes the NodeMCU (ESP-8266) for the smaller-scale micro-controller board to interface with the gas sensors, Django for the front end web interface, and Python in the backend for systematic AI. A comprehensive indoor air monitoring and analysis system shall serve like a fitness tracker for your house. This system will proactively alert users if it can predict a rise in the concentration of gas levels. The primary purpose of ‘air miner' is to alert users proactively about a probable surge in the concentration of carbon monoxide. Along with this, it will give a complete analysis of the similar metrics. Air quality monitoring system for city uses multiple sensors with location co-ordinate. AQI LED indicator is actuated as per pollution level, and the real-time pollution level is visualized using the line graph.
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"COST 68 bis was more extensive in scope than the initial project since it covered both treatment and use of sewage sludge. This meant that the topics included both the engineering and economics aspects of sludge processing at sewage works and the environmental aspects of sludge disposal particularly in regard to its utilisation as a fertilizer in agriculture. The use of sewage sludge in this way is important in most countries and it was recognised that co-ordinated research was desirable into both the possible adverse environmental effects of heavy metals and pathogens in sludges and the beneficial effects of plant nutrients in sludge. The problem of odour nuisance arising from the handling and spreading of sewage sludge was also recognised as an important subject-area for research. Under COST 68 bis, five Working Parties were established to co-ordinate the various areas of research. As a 'Concerted Action1, no direct funding was available from the European Commission to finance research projects on sewage sludge, each country being expected to contribute its own publicly-funded projects to the common ’pool*. COST 68 bis ran from 1977 to 1980(2) and was followed by an extension programme - COST 68 ter - which ran from 1981 to 1983(3). In 1983, it was decided to further extend this Concerted Action but to widen the range of research topics in the scientific programme to include animal manures. The renewed programme was designated COST Project 681 'Treatment and Use of Organic Sludges and Liquid Agricultural Wastes'. It is obvious that sewage sludges and farm manures have many aspects in common particularly with regard to handling and treatment techniques and to the environmental impact (e.g. odour) which can occur from their utilisation on land. On the other hand, from the administrative point of view, sewage sludge and farm manures are in two different 'worlds'. Sewage sludge is the general responsibility of public authorities while responsibility for disposing of animal manures belong mainly to the private farming sector. Funding for research on the two types of waste, even if from Government sources, is usually from different Departments and there is little cross-involvement of research scientists in the two sectors. Nonetheless, the COST 681 activity is attempting to promote some co-ordination of effort between the two research areas and, hopefully, this will result in mutual benefit to both those authorities responsible for sewage sludge treatment and those concerned with farm manures and their disposal. This joint Workshop on 'odours' is a good example of the type of co-operation, and sharing of information on a common problem, which can be of great mutual benefit to both sectors. PARTICIPATING COUNTRIES". En Odour Prevention and Control of Organic Sludge and Livestock Farming, 17. CRC Press, 1986. http://dx.doi.org/10.1201/9781482286311-11.
Texto completoActas de conferencias sobre el tema "Bit (ordinateur)"
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Nielsen, Kristian P., Jakob J. Stamnes, Knut Stamnes y Johan Moan. "A Discrete Ordinate Radiative Transfer Model of Human Skin Tissue: The Importance of Melanosome Scattering". En Biomedical Topical Meeting. Washington, D.C.: OSA, 2006. http://dx.doi.org/10.1364/bio.2006.me43.
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Shkundalov, Danylo y Tatjana Vilutienė. "A new approach for extending the possibilities of collaboration between BIM, GIS and Web environments to increase the efficiency of building space management". En The 13th international scientific conference “Modern Building Materials, Structures and Techniques”. Vilnius Gediminas Technical University, 2019. http://dx.doi.org/10.3846/mbmst.2019.057.
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The paper presents the approach that extends the opportunities of Web environments in BIM model processing and allows implementation of the bigger amount of analysis that is based on the object’s positioning. With the developed relations, the objects in the BIM model can be considered not just like independent 3D objects in the WebGL environment but as objects that are linked between each other and can act by the rules that defined to each type of the objects. Correlated co-ordinates will be useful for the architects, building operators and facility managers who use the BIM model for the management of the building and its components. This method can be used to increase the effectiveness of space management, clash detection, relocation management and space programming as well as existing conditions modelling and lighting analysis can be done in a way that is more efficient due to possibility of implementation of the survey coordinate system that will give the coordinates to each object in the scene.
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Jiao, Jian y Zhixiong Guo. "Simulation of Focused Radiation Propagation and Transient Heat Transfer in Turbid Tissues". En ASME 2009 Heat Transfer Summer Conference collocated with the InterPACK09 and 3rd Energy Sustainability Conferences. ASMEDC, 2009. http://dx.doi.org/10.1115/ht2009-88261.
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Thermal analysis of a cylindrical tissue subject to a train of ultrashort pulse irradiations was made by developing a combined time-dependent radiation and conduction bio-heat transfer model. Ultrashort pulsed radiation transport in the cylindrical tissue is simulated using the transient discrete ordinate method. Treatment of focused beam is introduced. The model skin tissue is stratified as three layers with different optical, thermal and physiological properties. Comparisons between the collimated irradiation and focused beam are conducted. The effect of pulse train is investigated.
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Jiao, Jian y Zhixiong Guo. "Bio-Heat Transfer in a Model Skin Subject to a Train of Short Pulse Irradiation". En ASME 2008 International Mechanical Engineering Congress and Exposition. ASMEDC, 2008. http://dx.doi.org/10.1115/imece2008-66368.
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Thermal analysis of biological tissues subject to a train of ultrashort pulse irradiations was made of developing a combined time-dependent radiation and conduction bio-heat transfer model. A model skin tissue stratified as three layers with different optical, thermal and physiological properties was considered. Temperature response of the skin tissue exposed to a single ultrashort pulse irradiation was firstly analyzed by the finite volume method in combination with the transient discrete ordinates method. This temperature rise was found to reach pseudo steady state within an extremely short time period in which thermal diffusion is negligible. Since the tissue properties were assumed to be constant during a train of pulse irradiation, this temperature rise subject to a single pulse can be employed for repeated pulses. In the same time, Pennes’ equation was employed to study the bio-heat transfer in the meso-time scale. The effects of pulse strengths and repetition rate on the temperature response in the multi-layer skin tissue were investigated.
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Elmoutawakkil, N., S. Bouzoubaa, S. Bellemkhannate y I. Benyahya. "Flux de travail du guidage tridimensionnel en chirurgie orale". En 66ème Congrès de la SFCO. Les Ulis, France: EDP Sciences, 2020. http://dx.doi.org/10.1051/sfco/20206602005.
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L’implantologie assistée par ordinateur permet de sécuriser le geste, de prévoir les potentielles complications, d’anticiper la séquence de forage et le choix de l’implant et donne la possibilité d’avoir une transition entre la simulation et la chirurgie à l’aide d’un guide chirurgical, elle est utilisée pour faciliter l’établissement d’un diagnostic précis et du plan de traitement idéal[1]. Dès que les images radiologiques (sous format DICOM) sont acquises suite à la réalisation d’une tomodensitométrie ou d’un cône-beam, elles sont transférées dans un logiciel de planification qui permettra la transformation des vues bidimensionnelles en une vision tridimensionnelle, pour évaluer la quantité et la qualité du volume osseux disponible et réaliser une représentation colorée et tridimensionnelle des éléments anatomiques présents sur les coupes dans le but de réaliser une simulation implantaire, Une fois placé, l’implant est visualisé immédiatement dans les trois plans de lespace, ensuite le praticien peut anticiper les caractéristiques du pilier, l’axe prothétique, et simuler l’épaisseur de la gencive. Ainsi un guide chirurgical à appui dentaire, muqueux ou osseux est conçu, à sa réception du guide, le fabricant fournit une feuille de route correspondant au système implantaire et à la trousse chirurgicale utilisée. Elle contient toutes les informations pour chaque implant et peut être complété par des cuillères et des porte-implants individualisés.Les résultats montrent que les écarts entre la réalité clinique et la planification émanent du type d’appui du guide. Un bio-modèle peut être imprimé en 3D, il servira comme outil pédagogique pour expliquer au patient le déroulement du projet et permettra également de réaliser une chirurgie « sèche » en amont de la pose d’implant ; et dans le cas de régénération osseuse guidée utilisant des grilles en titane il servira de support pour les préformer dans l’asepsie totale [2]. Les prothèses provisoires immédiates sont également réalisées au besoin, grâce à la superposition de la conception tridimensionnelle implantaire au modèle du patient scanné optiquement éviteant les erreurs de conception des prothèses immédiates. En oncologie buccale, la planification assistée permettra en segmentant la tumeur, de visualiser ses marges et sa taille, de réaliser un guide de résection et de customiser les plaques et les treillis imprimés en 3D. L’avènement de la conception et de la fabrication assistée par ordinateur a permis de révolutionner la chirurgie orale et de supprimer les erreurs opérateur dépendant en codifiant les actes, le travail présenté vise à décrire les différentes étapes du flux de travail optimal à adopter en chirurgie orale, permettant la réalisation de chirurgie totalement assistée, la conception et la fabrication de différents guides de forage et de résection osseuse ainsi que des prothèses provisoires immédiates [3].
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Mecit, Ahmet Murat y Fletcher Miller. "A Comparison Between the Monte Carlo Ray Trace and the FLUENT Discrete Ordinates Methods for Treating Solar Input to a Particle Receiver". En ASME 2014 8th International Conference on Energy Sustainability collocated with the ASME 2014 12th International Conference on Fuel Cell Science, Engineering and Technology. American Society of Mechanical Engineers, 2014. http://dx.doi.org/10.1115/es2014-6412.
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A new type of high temperature solar receiver for Brayton Cycle power towers is being designed and built in the Combustion and Solar Energy Laboratory at San Diego State University under a DOE Sunshot Award. The Small Particle Solar Receiver is a pressurized vessel with a window to admit concentrated solar radiation that utilizes a gas-particle suspension for absorption and heat transfer. As the particles absorb the radiation that enters the receiver through the window, the carrier fluid (air in this case) heats which oxidizes the particles and the flow leaves the receiver as a clear gas stream. After passing through an in-line combustor if needed, this hot gas is used to power a turbine to generate electricity. The numerical modelling of the receiver is broken into three main pieces: Monte Carlo Ray Trace (MCRT) method (written in FORTRAN), ANSYS Fluent (CFD), and the User Defined function (written in C code) for oxidation. Each piece has its advantages, disadvantages, and limitations and the three pieces are coupled to finalize the calculation. While we have successfully demonstrated this approach to obtaining the velocity and temperature fields, one big challenge to this method is that the definition of the geometry is a time consuming programming task when using MCRT. On the other hand, arbitrary geometries can be easily modelled by Computational Fluid Dynamics (CFD) codes such as FLUENT. The goal of this study is to limit the use of MCRT method to determining the appropriate input boundary condition on the outside of the window of the receiver and to use the built-in Discrete Ordinates (DO) method for all the radiation internal to the receiver and leaving the receiver due to emission. To reach the goal, this paper focuses on the DO method implemented within FLUENT. An earlier study on this subject is based and advanced. Appropriate radiation input for the DO method is extensively discussed. MIRVAL is used to simulate the heliostat field and VEGAS is used to simulate a lab-scale solar simulator; both of these codes utilize the MCRT method and provide intensity information on a surface. Output from these codes is discretized into DO parameters allowing the solution to proceed in FLUENT. Suitable benchmarks in FLUENT are used in a cylindrical geometry representing the receiver for the comparison and validation. This method will allow FLUENT to be used for a variety of problems involving concentrated solar energy.
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Dutta, Ashim, Kyunghan Kim, Kunal Mitra y Zhixiong Guo. "Experimental Measurements and Numerical Modeling Validation of Temperature Distribution in Tissue Medium During Short Pulse Laser Irradiation". En ASME 2007 International Mechanical Engineering Congress and Exposition. ASMEDC, 2007. http://dx.doi.org/10.1115/imece2007-41295.
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The objective of this paper is to analyze the temperature distributions and heat affected zone in skin tissue medium when irradiated with either a collimated or a focused laser beam from a short pulse laser source. Single-layer and three-layer tissue phantoms containing embedded inhomogeneities are used as a model of human skin tissue having subsurface tumor. Q-switched Nd:YAG laser is used in this study. Experimental measurements of axial and radial temperature distribution in the tissue phantom are compared with the numerical modeling results. For numerical modeling, the transient radiative transport equation is first solved using discrete ordinates method for obtaining the intensity distribution and radiative heat flux inside the tissue medium. Then the temperature distribution is obtained by coupling the bio-heat transfer equation with either hyperbolic non-Fourier or parabolic Fourier heat conduction model. The hyperbolic heat conduction equation is solved using MacCormack’s scheme with error terms correction. It is observed that experimentally measured temperature distribution is in good agreement with that predicted by hyperbolic heat conduction model. The experimental measurements also demonstrate that converging laser beam focused directly at the subsurface location can produce desired high temperature at that location as compared to that produced by collimated laser beam for the same laser parameters.
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Åman, Rafael, Heikki Handroos, Hannu Kärkkäinen, Jari Jussila y Pasi Korkealaakso. "Novel ICT-Enabled Collaborative Design Processes and Tools for Developing Non-Road Mobile Machinery". En ASME/BATH 2015 Symposium on Fluid Power and Motion Control. American Society of Mechanical Engineers, 2015. http://dx.doi.org/10.1115/fpmc2015-9571.
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The improvement of the energy efficiency is an important topic for non-road mobile machinery developers and manufacturers. These machines normally use fluid power transmission in drivelines and working actuators. New energy efficient technologies, e.g. a hybrid power transmission with an energy recovery feature, have been introduced. Currently most of the manufacturers are still using conventional technologies in their product development process. Human operators have an effect on the overall efficiency of the machines. Taking into account the human effects is difficult and expensive using the conventional design processes and tools. The objective of this study is to provide international machine manufacturers instrumental, yet novel, community and simulation-based (ICT-enabled) tools/methods for the strategic and cost effective development of their product practices and design processes. The development of models and methods will allow for rapid real-time virtual prototyping of complex machines and machine fleets that operate within a number of worksites or geographical conditions. The introduction of this state-of-the art (and going beyond) advancement in real-time virtual technology, simulation, internet based design technologies and software, cyber-physical and big data processing systems, will present a holistic approach to improve the entire product life. Targeted user groups are manufacturers of non-road mobile machinery (i.e. excavators, wheel loaders, etc.). These machines and production systems share the following key features: 1) They are complex mechatronic systems with several interconnections between hydraulic drives; mechanics, electronics, software and 2) they include autonomous, semiautonomous and human driven operated systems. Methods developed will enable machine manufacturers’ access to technologies that will lead to a more cost effective consumer ordinated, life cycle optimization process. This paper will introduce the method of developing customized products in a fast, agile and networked way that will lead to significantly reduced life-cycle costs.
Informes sobre el tema "Bit (ordinateur)"
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Mbani, Benson, Timm Schoening y Jens Greinert. Automated and Integrated Seafloor Classification Workflow (AI-SCW). GEOMAR, mayo de 2023. http://dx.doi.org/10.3289/sw_2_2023.
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The Automated and Integrated Seafloor Classification Workflow (AI-SCW) is a semi-automated underwater image processing pipeline that has been customized for use in classifying the seafloor into semantic habitat categories. The current implementation has been tested against a sequence of underwater images collected by the Ocean Floor Observation System (OFOS), in the Clarion-Clipperton Zone of the Pacific Ocean. Despite this, the workflow could also be applied to images acquired by other platforms such as an Autonomous Underwater Vehicle (AUV), or Remotely Operated Vehicle (ROV). The modules in AI-SCW have been implemented using the python programming language, specifically using libraries such as scikit-image for image processing, scikit-learn for machine learning and dimensionality reduction, keras for computer vision with deep learning, and matplotlib for generating visualizations. Therefore, AI-SCW modularized implementation allows users to accomplish a variety of underwater computer vision tasks, which include: detecting laser points from the underwater images for use in scale determination; performing contrast enhancement and color normalization to improve the visual quality of the images; semi-automated generation of annotations to be used downstream during supervised classification; training a convolutional neural network (Inception v3) using the generated annotations to semantically classify each image into one of pre-defined seafloor habitat categories; evaluating sampling strategies for generation of balanced training images to be used for fitting an unsupervised k-means classifier; and visualization of classification results in both feature space view and in map view geospatial co-ordinates. Thus, the workflow is useful for a quick but objective generation of image-based seafloor habitat maps to support monitoring of remote benthic ecosystems.
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Kira, Beatriz, Rutendo Tavengerwei y Valary Mumbo. Points à examiner à l'approche des négociations de Phase II de la ZLECAf: enjeux de la politique commerciale numérique dans quatre pays d'Afrique subsaharienne. Digital Pathways at Oxford, marzo de 2022. http://dx.doi.org/10.35489/bsg-dp-wp_2022/01.
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Realities such as the COVID-19 pandemic have expedited the move to online operations, highlighting the undeniable fact that the world is continuing to go digital. This emphasises the need for policymakers to regulate in a manner that allows them to harness digital trade benefits while also avoiding associated risk. However, given that digital trade remains unco-ordinated globally, with countries adopting different approaches to policy issues, national regulatory divergence on the matter continues, placing limits on the benefits that countries can obtain from digital trade. Given these disparities, ahead of the African Continental Free Trade Area (AfCFTA) Phase II Negotiations, African countries have been considering the best way to harmonise regulations on issues related to digital trade. To do this effectively, AfCFTA members need to identify where divergencies exist in their domestic regulatory systems. This will allow AfCFTA members to determine where harmonisation is possible, as well as what is needed to achieve such harmonisation. This report analyses the domestic regulations and policies of four focus countries – South Africa, Nigeria, Kenya and Senegal – comparing their regulatory approaches to five policy issues: i) regulation of online transactions; ii) cross-border data flows, data localisation, and personal data protection; iii) access to source code and technology transfer; iv) intermediary liability; and v) customs duties on electronic transmissions. The study highlights where divergencies exist in adopted approaches, indicating the need for the four countries – and AfCFTA members in general – to carefully consider the implications of the divergences, and determine where it is possible and beneficial to harmonise approaches. This was intended to encourage AfCFTA member states to take ownership of these issues and reflect on the reforms needed. As seen in Table 1 below, the study shows that the four countries diverge on most of the five policy issues. There are differences in how all four countries regulate online transactions – that is, e-signatures and online consumer protection. Nigeria was the only country out of the four to recognise all types of e-signatures as legally equivalent. Kenya and Senegal only recognise specific e-signatures, which are either issued or validated by a recognised institution, while South Africa adopts a mixed approach, where it recognises all e-signatures as legally valid, but provides higher evidentiary weight to certain types of e-signatures. Only South Africa and Senegal have specific regulations relating to online consumer protection, while Nigeria and Kenya do not have any clear rules. With regards to cross border data flows, data localisation, and personal data protection, the study shows that all four focus countries have regulations that consist of elements borrowed from the European Union (EU) General Data Protection Regulation (GDPR). In particular, this was regarding the need for the data subject's consent, and also the adequacy requirement. Interestingly, the study also shows that South Africa, Kenya and Nigeria also adopt data localisation measures, although at different levels of strictness. South Africa’s data localisation laws are mostly imposed on data that is considered critical – which is then required to be processed within South African borders – while Nigeria requires all data to be processed and stored locally, using local servers. Kenya imposes data localisation measures that are mostly linked to its priority for data privacy. Out of the four focus countries, Senegal is the only country that does not impose any data localisation laws. Although the study shows that all four countries share a position on customs duties on electronic transmissions, it is also interesting to note that none of the four countries currently have domestic regulations or policies on the subject. The report concludes by highlighting that, as the AfCFTA Phase II Negotiations aim to arrive at harmonisation and to improve intra-African trade and international trade, AfCFTA members should reflect on their national policies and domestic regulations to determine where harmonisation is needed, and whether AfCFTA is the right platform for achieving this efficiently.