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Cognition, Computer science, Informatique, Sciences exactes et technologie, Exact sciences and technology, Sciences appliquees, Applied sciences, Informatique; automatique theorique; systemes, Computer science; control theory; systems, Informatique théorique, Theoretical computing, Recherche information. Graphe, Information retrieval. Graph, Logiciel, Software, Systèmes informatiques et systèmes répartis. Interface utilisateur, Computer systems and distributed systems. User interface, Conception assistée, Computer aided design, Intelligence artificielle, Artificial intelligence, Reconnaissance des formes. Traitement numérique des images. Géométrie algorithmique, Pattern recognition. Digital image processing. Computational geometry, Algorithme apprentissage, Learning algorithm, Algoritmo aprendizaje, Analyse scène, Scene analysis, Análisis escena, Apprentissage supervisé, Supervised learning, Aprendizaje supervisado, Conception assistée, Computer aided design, Concepción asistida, Image tridimensionnelle, Tridimensional image, Imagen tridimensional, Intelligence artificielle, Artificial intelligence, Inteligencia artificial, Interface utilisateur, User interface, Interfase usuario, Interrogation base donnée, Database query, Interrogación base datos, Minimisation, Minimization, Minimización, Mise à jour, Updating, Actualización, Modèle Markov, Markov model, Modelo Markov, Modélisation, Modeling, Modelización, Méthode graphe, Graph method, Método grafo, Méthode énergétique, Energy method, Método energético, Programmation discrète, Discrete programming, Programación discreta, Programmation mathématique, Mathematical programming, Programación matemática, Prototypage rapide, Rapid prototyping, Prototipificación rápida, Psycholinguistique, Psycholinguistics, Psicolinguística, Reconstruction image, Image reconstruction, Reconstrucción imagen, Stimulus acoustique, Acoustic stimulus, Estímulo acústico, Structure document, Document structure, Estructura documental, Système actif, Active system, Sistema activo, Système conversationnel, Interactive system, Sistema interactivo, Traitement image, Image processing, Procesamiento imagen, Vision ordinateur, Computer vision, Visión ordenador, Imprimante 3D, 3D printer, Impresora 3D, Informatique mobile, Mobile computing, Informática móvil, Active-teaming, Energy minimization, Image-based modeling, and Interactive 3D reconstruction

We refer to the task of recovering the 3D structure of an object or a scene using 2D images as image-based modeling. In this paper, we formulate the task of recovering the 3D structure as a discrete optimization problem solved via energy minimization. In this standard framework of a Markov random field (MRF) defined over the image we present algorithms that allow the user to intuitively interact with the algorithm. We introduce an algorithm where the user guides the process of image-based modeling to find and model the object of interest by manually interacting with the nodes of the graph. We develop end user applications using this algorithm that allow object of interest 3D modeling on a mobile device and 3D printing of the object of interest. We also propose an alternate active learning algorithm that guides the user input. An initial attempt is made at reconstructing the scene without supervision. Given the reconstruction, an active learning algorithm uses intuitive cues to quantify the uncertainty of the algorithm and suggest regions, querying the user to provide support for the uncertain regions via simple scribbles. These constraints are used to update the unary and the pairwise energies that, when solved, lead to better reconstructions. We show through machine experiments and a user study that the proposed approach intelligently queries the users for constraints, and users achieve better reconstructions of the scene faster, especially for scenes with textureless surfaces lacking strong textural or structural cues that algorithms typically require.

Computer science, Informatique, Sciences exactes et technologie, Exact sciences and technology, Sciences appliquees, Applied sciences, Informatique; automatique theorique; systemes, Computer science; control theory; systems, Logiciel, Software, Langages de programmation, Programming languages, Systèmes informatiques et systèmes répartis. Interface utilisateur, Computer systems and distributed systems. User interface, Intelligence artificielle, Artificial intelligence, Reconnaissance des formes. Traitement numérique des images. Géométrie algorithmique, Pattern recognition. Digital image processing. Computational geometry, Electronique, Electronics, Electronique des semiconducteurs. Microélectronique. Optoélectronique. Dispositifs à l'état solide, Semiconductor electronics. Microelectronics. Optoelectronics. Solid state devices, Circuits intégrés, Integrated circuits, Circuits intégrés par fonction (dont mémoires et processeurs), Integrated circuits by function (including memories and processors), Biométrie, Biometrics, Biometría, Calculateur embarqué, Boarded computer, Calculador embarque, Capacité mémoire, Memory capacity, Capacidad memoria, Compilation, Compilación, Conception conjointe, Codesign, Diseño conjunto, Densité élevée, High density, Densidad elevada, Etude expérimentale, Experimental study, Estudio experimental, Haute performance, High performance, Alto rendimiento, Langage VHDL, VHDL language, Lenguaje VHDL, Langage description matériel informatique, Hardware description languages, Langage description, Description language, Lenguaje descripción, Modélisation, Modeling, Modelización, Mot instruction très long, Very long instruction word, Palabra instrucción muy larga, Parallélisme instruction, Instruction level parallelism, Paralelismo instrucción, Paume, Palm, Palma(mano), Personnalisation, Customization, Personalización, Processeur VLIW, Very long instruction word processor, Procesador VLIW, Prototypage rapide, Rapid prototyping, Prototipificación rápida, Réseau porte programmable, Field programmable gate array, Red puerta programable, Réutilisation, Reuse, Reutilización, Système modulaire, Modular system, Sistema modular, Technologie avancée, Advanced technology, Tecnología avanzada, Temps réel, Real time, Tiempo real, Temps traitement, Processing time, Tiempo proceso, Traitement image, Image processing, Procesamiento imagen, Jeu d'instructions, Instruction set, Conjunto de instrucciones, Biometric system, FPGA, Real-time image processing, System design, and VLIW processor

Modern field programmable gate array (FPGA) chips, with their larger memory capacity and reconfigurability potential, are opening new frontiers in rapid prototyping of embedded systems. With the advent of high-density FPGAs, it is now possible to implement a high-performance VLIW (very long instruction word) processor core in an FPGA. With VLIW architecture, the processor effectiveness depends on the ability of compilers to provide sufficient ILP (instruction-level parallelism) from program code. This paper describes research result about enabling the VLIW processor model for real-time processing applications by exploiting FPGA technology. Our goals are to keep the flexibility of processors to shorten the development cycle, and to use the powerful FPGA resources to increase real-time performance. We present a flexible VLIW VHDL processor model with a variable instruction set and a customizable architecture which allows exploiting intrinsic parallelism of a target application using advanced compiler technology and implementing it in an optimal manner on FPGA. Some common algorithms of image processing were tested and validated using the proposed development cycle. We also realized the rapid prototyping of embedded contactless palmprint extraction on an FPGA Virtex-6 based board for a biometric application and obtained a processing time of 145.6 ms per image. Our approach applies some criteria for co-design tools: flexibility, modularity, performance, and reusability.

Cognition, Computer science, Informatique, Sciences exactes et technologie, Exact sciences and technology, Physique, Physics, Domaines classiques de la physique (y compris les applications), Fundamental areas of phenomenology (including applications), Mécanique des fluides, Fluid dynamics, Méthodes de calcul en mécanique des fluides, Computational methods in fluid dynamics, Sciences appliquees, Applied sciences, Informatique; automatique theorique; systemes, Computer science; control theory; systems, Informatique théorique, Theoretical computing, Algorithmique. Calculabilité. Arithmétique ordinateur, Algorithmics. Computability. Computer arithmetics, Logiciel, Software, Conception assistée, Computer aided design, Genie mecanique. Construction mecanique, Mechanical engineering. Machine design, Généralités, General, Algorithme évolutionniste, Evolutionary algorithm, Algoritmo evoluciónista, Application spatiale, Space application, Aplicación espacial, Aérodynamique, Aerodynamics, Aerodinámica, Aéronautique, Aeronautics, Aeronáutica, Aéronef, Aircraft, Aeronave, Conception assistée, Computer aided design, Concepción asistida, Conception ingénierie, Engineering design, Concepción ingeniería, Conception optimale, Optimal design, Concepción optimal, Dynamique fluide, Fluid dynamics, Dinámica fluido, Efficacité, Efficiency, Eficacia, Elément aéronef, Aircraft components, Modélisation, Modeling, Modelización, Mécanique fluide numérique, Computational fluid dynamics, Mecánica fluido numérica, Méthodologie, Methodology, Metodología, Outil logiciel, Software tool, Herramienta software, Prototypage rapide, Rapid prototyping, Prototipificación rápida, Système paramétrique, Parametric system, Sistema paramétrico, Conception générative, Generative design, Concepción generativa, Evolutionary algorithms, Optimisation, and Parametric design

Traditional CAD tools generate a static solution to a design problem. Parametric systems allow the user to explore many variations on that design theme. Such systems make the computer a generative design tool and are already used extensively as a rapid prototyping technique in architecture and aeronautics. Combining a design generation tool with an analysis software and an evolutionary algorithm provides a methodology for optimising designs. This work combines NASA's parametric aircraft design tool (OpenVSP) with a fluid dynamics solver (OpenFOAM) to create and analyse aircraft An evolutionary algorithm is then used to generate a range of aircraft that maximise lift and reduce drag while remaining within the framework of the original design. Our approach allows the designer to automatically optimise their chosen design and to generate models with improved aerodynamic efficiency. Different components on three aircraft models are varied to highlight the ease and effectiveness of the parametric model optimisation.

Polymers, paint and wood industries, Polymères, industries des peintures et bois, Sciences exactes et technologie, Exact sciences and technology, Sciences appliquees, Applied sciences, Industrie des polymeres, peintures, bois, Polymer industry, paints, wood, Technologie des polymères, Technology of polymers, Appareillage et mise en oeuvre, Machinery and processing, Matières plastiques, Plastics, Moulage, Moulding, Injection, Injection moulding, Divers, Miscellaneous, ABS, Acrilonitrilo butadieno estireno copolímero, Amide 12 polymère, Amide 12 polymer, Amida 12 polímero, Coefficient Poisson, Poisson ratio, Coeficiente Poisson, Effet température, Temperature effect, Efecto temperatura, Etude expérimentale, Experimental study, Estudio experimental, Forme tridimensionnelle, Three dimensional shape, Forma tridimensional, Module Young, Young modulus, Módulo Young, Moulage injection, Injection molding, Moldeo por inyección, Polymère aliphatique, Aliphatic polymer, Polímero alifático, Propagation ultrason, Ultrasonic propagation, Propriété mécanique, Mechanical properties, Propiedad mecánica, Propriété rhéologique, Rheological properties, Propiedad reológica, Prototypage rapide, Rapid prototyping, Prototipificación rápida, Sensibilité tactile, Tactile sensitivity, Sensibilidad tactil, Viscoélasticité, Viscoelasticity, Viscoelasticidad, Frittage laser, Attenuation measurement, Diffraction effect, Polyamide, Relative humidity, Temperature, Ultrasonic velocity measurement, and Viscous coefficients

Active touch localization based on a learning process of touch-disturbed broadband bending wave propagation in thin objects is used to transform any 3D surface into a multi-touch interface. Fast prototyping permits easy manufacturing of various 3D shapes that can be as quickly transformed into touch interfaces. The drawback is their weak mechanical stability with temperature. This paper details the temperature behavior differences between a sintered plastic such as polyamide polymer of type PA12 and raw injected Acrylonitrile-Butadiene-Styrene composite polymer (ABS), in particular how their physical parameters such as Young's modulus and Poisson's ratio are affected by temperature. Correlatively, longitudinal and transversal waves within injected and sintered plastics are investigated across a commercial temperature range of 10 °C to 70 °C. The internal grain structure in plastics obtained by laser sintering of powder makes these materials prone to stronger damping and clear non-linear temperature dependency of the shear wave velocity compared with injected plastics.

Computer science, Informatique, Security, safety, Sécurité (multidisciplinaire, général), Sciences exactes et technologie, Exact sciences and technology, Sciences appliquees, Applied sciences, Informatique; automatique theorique; systemes, Computer science; control theory; systems, Logiciel, Software, Systèmes informatiques et systèmes répartis. Interface utilisateur, Computer systems and distributed systems. User interface, Organisation des mémoires. Traitement des données, Memory organisation. Data processing, Systèmes d'information. Bases de données, Information systems. Data bases, Conception assistée, Computer aided design, Intelligence artificielle, Artificial intelligence, Reconnaissance des formes. Traitement numérique des images. Géométrie algorithmique, Pattern recognition. Digital image processing. Computational geometry, Attaque informatique, Computer attack, Ataque informática, Base de données répartie, Distributed database, Base repartida dato, Biométrie, Biometrics, Biometría, Conception assistée, Computer aided design, Concepción asistida, Contremesure, Countermeasurement, Contramedida, Faciès, Facies, Image tridimensionnelle, Tridimensional image, Imagen tridimensional, Masque, Mask, Máscara, Planéité, Flatness, Planeidad, Prototypage rapide, Rapid prototyping, Prototipificación rápida, Reconstruction image, Image reconstruction, Reconstrucción imagen, Sécurité, Safety, Seguridad, Texture, Textura, Traitement image, Image processing, Procesamiento imagen, Vision ordinateur, Computer vision, Visión ordenador, Vulnérabilité, Vulnerability, Vulnerabilidad, Attaque par mascarade, Spoofing attack, Ataque de suplantación de identidad, Caméra vidéo, Video cameras, Cámara de vídeo, Reconnaissance visage, Face recognition, Reconocimiento de cara, Système détection intrusion, Intrusion detection systems, Sistema de detección de intrusiones, Spoofing, face recognition, mask attack, and presentation attack

Spoofing is the act of masquerading as a valid user by falsifying data to gain an illegitimate access. Vulnerability of recognition systems to spoofing attacks (presentation attacks) is still an open security issue in biometrics domain and among all biometric traits, face is exposed to the most serious threat, since it is particularly easy to access and reproduce. In this paper, many different types of face spoofing attacks have been examined and various algorithms have been proposed to detect them. Mainly focusing on 2D attacks forged by displaying printed photos or replaying recorded videos on mobile devices, a significant portion of these studies ground their arguments on the flatness of the spoofing material in front of the sensor. However, with the advancements in 3D reconstruction and printing technologies, this assumption can no longer be maintained. In this paper, we aim to inspect the spoofing potential of subject-specific 3D facial masks for different recognition systems and address the detection problem of this more complex attack type. In order to assess the spoofing performance of 3D masks against 2D, 2.5D, and 3D face recognition and to analyze various texture-based countermeasures using both 2D and 2.5D data, a parallel study with comprehensive experiments is performed on two data sets: the Morpho database which is not publicly available and the newly distributed 3D mask attack database.

Electronics, Electronique, Mechanical engineering, Génie mécanique, Metrology and instrumentation, Métrologie et instrumentation, Sciences exactes et technologie, Exact sciences and technology, Physique, Physics, Generalites, General, Instruments, appareillage, composants et techniques communs à plusieurs branches de la physique et de l'astronomie, Instruments, apparatus, components and techniques common to several branches of physics and astronomy, Techniques et équipements généraux, General equipment and techniques, Transducteurs, Transducers, Actionneur électromagnétique, Electromagnetic actuators, Actionneur, Actuators, Angle contact, Contact angle, Cobalt, Effet champ magnétique, Magnetic field effects, Effet magnétomécanique, Magnetomechanical effects, Hystérésis, Hysteresis, Matériau composite, Composite materials, Matériau ferromagnétique, Ferromagnetic materials, Module élasticité, Elastic modulus, Mouillage, Wetting, Nanocomposite, Nanocomposites, Nanoparticule, Nanoparticles, Propriété surface, Surface properties, Prototypage rapide, Rapid prototyping, Prototipificación rápida, Siloxane(diméthyl) polymère, Dimethylsiloxane polymer, Siloxano(dimetil) polímero, Soupape, Valves, Traitement par plasma, Plasma assisted processing, Analyse mécanique dynamique, and Dynamic mechanical analysis

In this study, a new type of active membrane based on magnetic elastomer composite is manufactured, characterized and integrated into a simple valve. The simple and low-cost fabrication process combined with large displacement capability of the membrane is favorable for use in disposable fluidic devices. Passivated ferromagnetic cobalt nanoparticles (~37 nm) synthesized by the chemical route were embedded in polydimethylsiloxane (PDMS) to fabricate nano-composite flexible membranes. Magneto-mechanical and mechanical properties of the PDMS composite elastomeric membrane loaded with various concentrations of cobalt (Co) nanoparticles (between 15 and 75 % by weight) were studied. Dynamic mechanical analysis (DMA) measurements of the nanocomposite membranes were conducted as a function of the applied frequency (between 0.1 and 56 Hz). With higher concentration (50-wt%) of Co nanoparticles in PDMS, the elastic modulus was increased by 3-4 times as compared with that of membranes with lower concentrations of nanoparticles. Shore hardness was maximum for the nano-composite membrane loaded with 50-wt% of Co nanoparticles. A fluidic actuator with 400 μm thick PDMS membrane of 18 mm free diameter loaded with 50-wt% Co nanoparticles was manufactured and tested under external magnetic field. In the region where the magnetic field gradient is highest, high deflection of the membrane could be obtained (0.68 mm for 1 Tesla). However some hysteresis of the membrane deflection could be observed, even at very low frequency. Loading of PDMS with Co nanoparticles allowed a wider range of control of the wetting properties of PDMS surfaces under oxygen plasma treatment, from hydrophobic to hydrophilic to super-hydrophilic. Tunability in hydrophilicity could be achieved by varying the process parameters as verified by contact angles and Fourier transforms infrared (FTIR) spectra before and after plasma treatment. Under certain conditions, 50 % Cobalt-PDMS membrane surfaces exhibited a super-hydrophilic behavior (contact angle ~5°).

Biomedical engineering, Génie biomédical, Sciences biologiques et medicales, Biological and medical sciences, Sciences medicales, Medical sciences, Tumeurs, Tumors, Tumeurs multiples. Tumeurs solides. Tumeurs chez l'enfant (généralités), Multiple tumors. Solid tumors. Tumors in childhood (general aspects), Chirurgie (generalites). Transplantations, greffes d'organes et de tissus. Pathologie des greffons, Surgery (general aspects). Transplantations, organ and tissue grafts. Graft diseases, Technologie. Biomatériaux. Equipements, Technology. Biomaterials. Equipments, Cancer, Cáncer, Agrégat, Aggregate, Agregado, Criblage, Screening, Cernido, Dépistage, Medical screening, Descubrimiento, Médicament, Drug, Medicamento, Prototypage rapide, Rapid prototyping, Prototipificación rápida, Tumeur maligne, Malignant tumor, and Tumor maligno

Microwell technology has revolutionized many aspects of in vitro cellular studies from 2D traditional cultures to 3D in vivo-like functional assays. However, existing lithography-based approaches are often costly and time-consuming. This study presents a rapid, low-cost prototyping method of CO2 laser ablation of a conventional untreated culture dish to create concave microwells used for generating multicellular aggregates, which can be readily available for general laboratories. Polymethylmethacrylate (PMMA), polydimethylsiloxane (PDMS), and polystyrene (PS) microwells are investigated, and each produces distinctive microwell features. Among these three materials, PS cell culture dishes produce the optimal surface smoothness and roundness. A549 lung cancer cells are grown to form cancer aggregates of controllable size from ≈40 to ≈80 μm in PS microwells. Functional assays of spheroids are performed to study migration on 2D substrates and in 3D hydrogel conditions as a step towards recapitulating the dissemination of cancer cells. Preclinical anti-cancer drug screening is investigated and reveals considerable differences between 2D and 3D conditions, indicating the importance of assay type as well as the utility of the present approach.

Telecommunications, Télécommunications, Sciences exactes et technologie, Exact sciences and technology, Sciences appliquees, Applied sciences, Telecommunications et theorie de l'information, Telecommunications and information theory, Télécommunications, Telecommunications, Radiocommunications, Antennes, Antennas, Antenne fil, Wire antenna, Antena hilo, Antenne hélicoïdale, Helical antenna, Antena helicoidal, Antenne sphérique, Spherical antenna, Antena esférica, Impression, Printing, Impresión, Prototypage rapide, Rapid prototyping, Prototipificación rápida, Stratification, Estratificación, 3D printing, electrically small antennas, nanocrystalline copper, rapid prototyping, selective laser sintering, and spherical antennas

It is shown how modern rapid prototyping technologies can be applied for quick and inexpensive, but still accurate, fabrication of electrically small wire antennas. A well known folded spherical helix antenna and a novel spherical zigzag antenna have been fabricated and tested, exhibiting the impedance and radiation characteristics in close agreement with those predicted numerically.

Polymers, paint and wood industries, Polymères, industries des peintures et bois, Sciences exactes et technologie, Exact sciences and technology, Sciences appliquees, Applied sciences, Industrie des polymeres, peintures, bois, Polymer industry, paints, wood, Technologie des polymères, Technology of polymers, Formes d'application et semiproduits, Forms of application and semi-finished materials, Divers, Miscellaneous, Sciences biologiques et medicales, Biological and medical sciences, Sciences medicales, Medical sciences, Chirurgie (generalites). Transplantations, greffes d'organes et de tissus. Pathologie des greffons, Surgery (general aspects). Transplantations, organ and tissue grafts. Graft diseases, Chirurgie cardiaque, Surgery of the heart, Biocompatibilité, Biocompatibility, Biocompatibilidad, Biodégradabilité, Biodegradability, Biodegradabilidad, Biomatériau, Biomaterial, Cardiologie, Cardiology, Cardiología, Diffusion molécule, Molecule scattering, Difusión molécula, Electrofilage, Electrospinning, Electrohilado, Ester polymère, Ester polymer, Ester polímero, Etat actuel, State of the art, Estado actual, Fibre artificielle, Artificial fiber, Fibra artificial, Fibre synthétique, Synthetic fiber, Fibra sintética, Frittage laser sélectif, Selective laser sintering, Sinterizacion laser selectiva, Génie tissulaire, Tissue engineering, Ingeniería de tejidos, Lyophilisation, Freeze drying, Liofilización, Morphologie, Morphology, Morfología, Méthode ablation laser, Laser ablation technique, Photolithographie, Photolithography, Fotolitografía, Polymère naturel, Natural polymer, Polímero natural, Procédé expansion, Foaming process, Procedimiento expansión, Procédé fabrication, Manufacturing process, Procedimiento fabricación, Propriété biologique, Biological properties, Propiedad biológica, Propriété mécanique, Mechanical properties, Propiedad mecánica, Prototypage rapide, Rapid prototyping, Prototipificación rápida, Coulée solution, Echafaudage tissulaire, cardiac tissue engineering, conventional techniques, rapid prototyping, and scaffolds

Cardiac tissue engineering (TE) is an emerging field, whose main goal is the development of innovative strategies for the treatment of heart diseases, with the aim of overcoming the drawbacks of traditional therapies. One of these strategies involves the implantation of three-dimensional matrices (scaffolds) capable of supporting tissue formation. Scaffolds designed and fabricated for such application should meet several requirements, concerning both the scaffold-forming materials and the properties of the scaffold itself. A scaffold for cardiac TE should be biocompatible and biodegradable, mimic the properties of the native cardiac tissue, provide a mechanical support to the regenerating heart and possess an interconnected porous structure to favour cell migration, nutrient and oxygen diffusion, and waste removal. Moreover, the mimesis of myocardium characteristic anisotropy is attracting increasing interest to provide engineered constructs with the possibility to be structurally and mechanically integrated in native tissue. Several conventional and non-conventional fabrication techniques have been explored in the literature to produce polymeric scaffolds meeting all these requirements. This review describes these techniques, with a focus on their advantages and disadvantages, and their flexibility, with the final goal of providing the reader with the primal knowledge necessary to develop an effective strategy in cardiac TE.

Electronics, Electronique, Optics, Optique, Telecommunications, Télécommunications, Sciences exactes et technologie, Exact sciences and technology, Sciences appliquees, Applied sciences, Electronique, Electronics, Circuits électriques, optiques et optoélectroniques, Electric, optical and optoelectronic circuits, Propriétés des circuits, Circuit properties, Circuits hyperfréquences, circuits intégrés hyperfréquences, lignes de transmission hyperfréquences, circuits à ondes submillimétriques, Microwave circuits, microwave integrated circuits, microwave transmission lines, submillimeter wave circuits, Hyperfréquence, Microwave, Hiperfrecuencia, Onde millimétrique, Millimetric wave, Onda milimétrica, Alimentation antenne, Antenna feeds, Bande Q, Q band, Banda Q, Jonction guide onde, Waveguide junction, Unión guía onda, Multicouche, Multiple layer, Capa múltiple, Polarimètre, Polarimeter, Polarímetro, Polarimétrie, Polarimetry, Polarimetría, Prototypage rapide, Rapid prototyping, Prototipificación rápida, Radioastronomie, Radio astronomy, Radioastronomía, Stratification, Estratificación, Système 2 canaux, Two channel system, Sistema 2 canales, Transducteur, Transducer, Transductor, polarimetry, radio astronomy, and waveguide junctions

This paper presents a Q-band orthomode transducer (OMT) that has been designed according to the mechanical constraints of the platelet (multi-layer) manufacturing strategy. It is composed of a twofold symmetric coupling section with two electrically identical recombination networks. The two OMT outputs lay on the same plane to provide a suitable interface to the correlation unit. The two channels are equalized in both magnitude and phase according to the correlation polarimeter requirements. They also exhibit a very low cross-coupling (- 50 dB) and good reflection levels (-28 dB) in the 21% bandwidth.

Mechanical engineering, Génie mécanique, Materials, Matériaux, Metrology and instrumentation, Métrologie et instrumentation, Sciences exactes et technologie, Exact sciences and technology, Sciences appliquees, Applied sciences, Industrie des polymeres, peintures, bois, Polymer industry, paints, wood, Technologie des polymères, Technology of polymers, Appareillage et mise en oeuvre, Machinery and processing, Matières plastiques, Plastics, Usinage, Machining, Genie mecanique. Construction mecanique, Mechanical engineering. Machine design, Mécanique de précision. Horlogerie, Precision engineering, watch making, Mécanique fluide, Fluid mechanics, Mecánica flúido, Analyse factorielle, Factor analysis, Análisis factorial, Carbonate polymère, Polycarbonate, Carbonato polímero, Composé organique, Organic compounds, Compuesto orgánico, Dispositif expérimental, Experimental device, Dispositivo experimental, Fraisage, Milling, Fresado, Microfluidique, Microfluidics, Microfluidic, Mécanique précision, Precision engineering, Mecánica precisión, Optimisation, Optimization, Optimización, Prototypage rapide, Rapid prototyping, Prototipificación rápida, Rugosité, Roughness, Rugosidad, Micromilling, and Polymer microfluidic device

Rapidly prototyping a polymer microfluidic device is a growing interest for various applications and micromilling is one of the common approaches to manufacture polymer microfluidic devices. The advantages of using micromilling for polymer microfluidic devices include shorter fabrication process, lower cost, easier user interface, and being capable of fabricating complicated structures, which make micromilling a perfect tool in research idea testing and validation. The aim of this study is to understand the impact of each micromilling parameter to the surface roughness on a polycarbonate substrate, followed by the factor analysis to determine the optimal cutting conditions. The parameters included spindle speed, feed rate, and the depth of cut, and the roughness was measured by a stylus profilemeter. The smallest roughness achieved was 0.127 μm with the spindle speed of 20,000 rpm, feed rate of 300 mm/min, and the depth of cut of 10 μm. Factor analysis was used to determine that the spindle speed has the largest impact while the depth of cut has the minimized impact to the surface quality. To further confirm the optimal cutting conditions, twelve reservoirs were micromilled with the optimal cutting conditions and the average roughness is 0.14 μm with a stand deviation of 0.08 μm.

Inorganic chemistry, Chimie minérale, Crystallography, Cristallographie cristallogenèse, Metallurgy, welding, Métallurgie, soudage, Condensed state physics, Physique de l'état condensé, Sciences exactes et technologie, Exact sciences and technology, Physique, Physics, Etat condense: structure electronique, proprietes electriques, magnetiques et optiques, Condensed matter: electronic structure, electrical, magnetic, and optical properties, Propriétés et matériaux magnétiques, Magnetic properties and materials, Propriétés magnétiques des nanostructures, Magnetic properties of nanostructures, Domaines interdisciplinaires: science des materiaux; rheologie, Cross-disciplinary physics: materials science; rheology, Science des matériaux, Materials science, Nanomatériaux et nanostructures : fabrication et caractèrisation, Nanoscale materials and structures: fabrication and characterization, Matériaux nanocristallins, Nanocrystalline materials, Bore alliage, Boron alloys, Déformation à chaud, Hot deformation, Deformación en caliente, Fer alliage, Iron alloys, Filage inverse, Indirect extrusion, Extrusión inversa, Filage état liquide, Melt spinning, Force coercitive, Coercive force, Hystérésis magnétique, Magnetic hysteresis, Lanthanide alliage, Rare earth alloys, Métal transition alliage, Transition element alloys, Nanocristal, Nanocrystal, Néodyme alliage, Neodymium alloys, Pressage, Pressing, Prototypage rapide, Rapid prototyping, Prototipificación rápida, Synthèse nanomatériau, Nanomaterial synthesis, Síntesis nanomaterial, Texture, Accepted 26 November 2013, Available online 2 December 2013, Received 15 October 2013, and Received in revised form 25 November 2013

In order to reduce the amount of material waste and therefore to use the precious rare earth element Nd in a more efficient way, routes for the production of crack-free hot-deformed nanocrystalline Nd-Fe-B magnets (using melt-spun ribbons as a precursor) have been investigated. In contrast to the conventional route in which material flows into a cavity, pressing tool has been used in order to exert a back pressure during backward extrusion, leading to crack-free and net-shape production of radially oriented ring magnets, without detrimental influence on magnetic properties. Micrographs demonstrate overall good alignment of elongated platelet shaped grains with radially oriented c-axis in most parts of the ring. A mean remanence Jr = 1.27 T and coercivity μ0iHc = 1.5 T has been obtained. Degree of texture reaches around 0.7. Furthermore, die-upsetting has been performed for different degrees of deformation to obtain crack-free, mechanically and magnetically homogenous, axially oriented tablet magnets.

Chemical engineering, Génie chimique, Computer science, Informatique, Sciences exactes et technologie, Exact sciences and technology, Physique, Physics, Domaines classiques de la physique (y compris les applications), Fundamental areas of phenomenology (including applications), Mécanique des fluides, Fluid dynamics, Méthodes de calcul en mécanique des fluides, Computational methods in fluid dynamics, Ecoulements dans les tubes, les canaux et les conduites, Flows in ducts, channels, nozzles, and conduits, Sciences appliquees, Applied sciences, Genie mecanique. Construction mecanique, Mechanical engineering. Machine design, Généralités, General, Colonne garnissage, Packed column, Columna de relleno, Etude expérimentale, Experimental study, Estudio experimental, Format STL, STL format, Formato STL, Garnissage, Packing, Relleno, Imagerie RMN, Nuclear magnetic resonance imaging, Imaginería RMN, Lit garnissage, Packed bed, Lecho relleno, Matériau poreux, Porous material, Material poroso, Modélisation, Modeling, Modelización, Mécanique fluide numérique, Computational fluid dynamics, Mecánica fluido numérica, Mécanique fluide, Fluid mechanics, Mecánica flúido, Méthode Monte Carlo, Monte Carlo method, Método Monte Carlo, Méthode non invasive, Non invasive method, Método no invasivo, Perte charge, Pressure drop, Pérdida carga, Procédé dépôt, Deposition process, Procedimiento revestimiento, Prototypage rapide, Rapid prototyping, Prototipificación rápida, Stéréolithographie, Stereolithography, Stereolitografia, Tomodensitométrie, Computerized axial tomography, Tomodensitometría, Computational Fluid Dynamics, Packed Bed, Porous media, and Simulation

When analysing packed beds using CFD approaches, producing an accurate geometry is often challenging. Often a computational model is produced from non-invasive imaging of the packed bed using 3d MRI or μ-CT. This work pioneers the exact reverse of this, by creating a physical bed from the computational model using Additive Layer Manufacturing (ALM). The paper focuses on both experimental analysis and computational analysis of packed columns of spheres. A STL file is generated of a packed column formed using a Monte-Carlo packing algorithm, and this is meshed and analysed using Computational Fluid Dynamics. In addition to this, a physical model is created using ALM on a 3d printer. This allows us to analyse the identical bed geometry both computationally and experimentally and compare the two. Pressure drop and flow patterns are analysed within the bed in detail.

Metallurgy, welding, Métallurgie, soudage, Condensed state physics, Physique de l'état condensé, Sciences exactes et technologie, Exact sciences and technology, Physique, Physics, Domaines interdisciplinaires: science des materiaux; rheologie, Cross-disciplinary physics: materials science; rheology, Science des matériaux, Materials science, Diagrammes de phases et microstructures développées par solidification et par transformations de phases solide-solide, Phase diagrams and microstructures developed by solidification and solid-solid phase transformations, Solidification, Sciences appliquees, Applied sciences, Metaux. Metallurgie, Metals. Metallurgy, Transformation de matériaux métalliques, Production techniques, Traitements de surface, Surface treatment, Acier inoxydable 316L, Stainless steel-316L, Acier inoxydable austénitique, Austenitic stainless steel, Acier inoxydable, Stainless steels, Additif, Additives, Diffusion, Scattering, Fabrication, Fusion laser, Laser fusion, Interface, Interfaces, Prototypage rapide, Rapid prototyping, Prototipificación rápida, 3D printing, Additive manufacturing, Multi-material, and Selective laser melting

Multi-material processing in selective laser melting using a novel approach, by the separation of two different materials within a single dispensing coating system was investigated. 316L stainless steel and UNS C18400 Cu alloy multi-material samples were produced using selective laser melting and their interfacial characteristics were analyzed using focused ion beam, scanning electron microscopy, energy dispersive spectroscopy and electron back scattered diffraction techniques. A substantial amount of Fe and Cu element diffusion was observed at the bond interface suggesting good metallurgical bonding. Quantitative evidence of good bonding at the interface was also obtained from the tensile tests where the fracture was initiated at the copper region. Nevertheless, the tensile strength of steel/Cu SLM parts was evaluated to be 310 ± 18 MPa and the variation in microhardness values was found to be gradual along the bonding interface from the steel region (256 ± 7 HV0.1) to the copper region (72 ± 3 HV0.1).

Control theory, operational research, Automatique, recherche opérationnelle, Mechanical engineering, Génie mécanique, Computer science, Informatique, Sciences exactes et technologie, Exact sciences and technology, Sciences appliquees, Applied sciences, Informatique; automatique theorique; systemes, Computer science; control theory; systems, Logiciel, Software, Conception assistée, Computer aided design, Genie mecanique. Construction mecanique, Mechanical engineering. Machine design, Généralités, General, Analyse scène, Scene analysis, Análisis escena, Biseau, Pinch out, Bisel, Chanfrein, Taper, Avellanado, Conception assistée, Computer aided design, Concepción asistida, Conception ingénierie, Engineering design, Concepción ingeniería, Conception intégrée, Integrated design, Concepción integrada, Epaulement, Fillet, Espaldón, Etude expérimentale, Experimental study, Estudio experimental, Ingénierie simultanée, Concurrent engineering, Ingeniería simultánea, Modèle dynamique, Dynamic model, Modelo dinámico, Modèle géométrique, Geometrical model, Modelo geométrico, Modélisation, Modeling, Modelización, Méthode décomposition, Decomposition method, Método descomposición, Méthode itérative, Iterative method, Método iterativo, Prototypage rapide, Rapid prototyping, Prototipificación rápida, Prototype, Prototipo, Représentation limite, Boundary representation, Representacion limite, Réalité virtuelle, Virtual reality, Realidad virtual, Résultat expérimental, Experimental result, Resultado experimental, Entité géométrique, Solid feature, Entidad sólida, B-rep model, Cell-based decomposition, Feature-based simplification, Sequential iterative volume decomposition, Volume split decomposition, and Wrap-around decomposition

When computer-aided design (CAD) models generated in the design phase are used for engineering activities such as engineering analysis, distributed collaborative design, and virtual prototyping, a process for simplifying the CAD models is needed. In this study, a feature-based simplification method of boundary representation (B-rep) models using sequential iterative volume decomposition is proposed. This method generates a feature-based model from a B-rep model by sequentially and iteratively applying the four volume decomposition methods (fillet, round, and chamfer decomposition; wrap-around decomposition; volume split decomposition; and cell-based decomposition). Then, feature-based simplification is applied to the generated feature-based model. To demonstrate the proposed method, a prototype system is implemented, and experiments with test cases are performed. Based on the experimental results, we verified that the proposed method successfully simplified B-rep models.

Polymers, paint and wood industries, Polymères, industries des peintures et bois, Sciences exactes et technologie, Exact sciences and technology, Sciences appliquees, Applied sciences, Industrie des polymeres, peintures, bois, Polymer industry, paints, wood, Technologie des polymères, Technology of polymers, Appareillage et mise en oeuvre, Machinery and processing, Matières plastiques, Plastics, Divers, Miscellaneous, Conception pièce, Piece design, Concepción pieza, Etude théorique, Theoretical study, Estudio teórico, Fabrication, Manufacturing, Fabricación, Forme commerciale, Commercial form, Forma comercial, Frittage laser sélectif, Selective laser sintering, Sinterizacion laser selectiva, Mode rupture, Fracture mode, Modo ruptura, Module conservation, Storage modulus, Módulo conservación, Modélisation, Modeling, Modelización, Méthode élément fini, Finite element method, Método elemento finito, Propriété mécanique, Mechanical properties, Propiedad mecánica, Propriété rhéologique, Rheological properties, Propiedad reológica, Propriété traction, Tensile property, Propiedad tracción, Prototypage rapide, Rapid prototyping, Prototipificación rápida, Simulation numérique, Numerical simulation, Simulación numérica, Styrène polymère, Styrene polymer, Estireno polímero, Vérification expérimentale, Experimental test, Verificación experimental, Fabrication additive, Additive manufacturing, CastForm polystyrene patterns, and Finite element analysis

Understanding the nature of part failure when using CastForm™ material for pattern generation is essential in the development of failure avoidance practices. Currently, many approaches employed in both research and industry rely on the use of physical supports to underpin the part, yet there is little research which explores their optimal implementation. In this paper, a detailed empirical investigation examines how the material characteristics of CastForm™ are affected during the thermal infiltration process, and how this may lead to part failure. Using Dynamic Mechanical Thermal Analysis, it is shown that increased temperature reduces the storage modulus of the material, leading to rubber-like behaviour at 60°C. The findings of this material investigation are used as input for the generation of a linear static FEA model, with which this research demonstrates how physical supports can be optimized in terms of the quantity used, and also their positioning relative to the part. Two industrial case studies illustrate this approach to part production, highlighting both the success of the FEA approach to eliminate part failures, and also the potential to improve knowledge for the process operators in the use of part supports.

Computer science, Informatique, Sciences exactes et technologie, Exact sciences and technology, Physique, Physics, Domaines classiques de la physique (y compris les applications), Fundamental areas of phenomenology (including applications), Acoustique, Acoustics, Transducteurs et dispositif pour la génération et la reproduction du son, Transduction; acoustical devices for the generation and reproduction of sound, Sciences appliquees, Applied sciences, Generalites, General aspects, Formation professionnelle. Personnel. Organisation du travail, Occupational training. Personnel. Work management, Informatique; automatique theorique; systemes, Computer science; control theory; systems, Logiciel, Software, Systèmes informatiques et systèmes répartis. Interface utilisateur, Computer systems and distributed systems. User interface, Intelligence artificielle, Artificial intelligence, Reconnaissance des formes. Traitement numérique des images. Géométrie algorithmique, Pattern recognition. Digital image processing. Computational geometry, Acoustique musicale, Musical acoustics, Acústica musical, Age, Edad, Audiovisuel, Audiovisual, Equipement audiovisuel, Audiovisual equipment, Equipo audiovisual, Estimation mouvement, Motion estimation, Estimación movimiento, Foire exposition, Exhibition, Parque exposición, Forme géométrique, Geometrical shape, Forma geométrica, Forme libre, Free form, Forma libre, Image tridimensionnelle, Tridimensional image, Imagen tridimensional, Interface utilisateur, User interface, Interfase usuario, Modèle géométrique, Geometrical model, Modelo geométrico, Métaphore, Metaphor, Metáfora, Poterie, Pottery, Alfarería, Profondeur champ, Depth of field, Profundidad campo, Prototypage rapide, Rapid prototyping, Prototipificación rápida, Réalité virtuelle, Virtual reality, Realidad virtual, Sculpture, Escultura, Son musical, Musical sound, Sonido musical, Temps réel, Real time, Tiempo real, Vision ordinateur, Computer vision, Visión ordenador, Acoustique audio, Audio acoustics, Acústica audio, Reconnaissance geste, Gesture recognition, Reconocimiento de gestos, Audio sonification, Hand gesture recognition, Virtual musical instrument, and Virtual pottery

In this paper, we present our approach towards designing and implementing a virtual 3D sound sculpting interface that creates audiovisual results using hand motions in real time. In the interface Virtual Pottery, we use the metaphor of pottery creation in order to adopt the natural hand motions to 3D spatial sculpting. Users can create their own pottery pieces by changing the position of their hands in real time, and also generate 3D sound sculptures based on pre-existing rules of music composition. The interface of Virtual Pottery can be categorized by shape design and camera sensing type. This paper describes how we developed the two versions of Virtual Pottery and implemented the technical aspects of the interfaces. Additionally, we investigate the ways of translating hand motions into musical sound. The accuracy of the detection of hand motions is crucial for translating natural hand motions into virtual reality. According to the results of preliminary evaluations, the accuracy of both motion-capture tracking system and portable depth sensing camera is as high as the actual data. We carried out user studies, which took into account information about the two exhibitions along with the various ages of users. Overall, Virtual Pottery serves as a bridge between the virtual environment and traditional art practices, with the consequence that it can lead to the cultivation of the deep potential of virtual musical instruments and future art education programs.

Polymers, paint and wood industries, Polymères, industries des peintures et bois, Sciences exactes et technologie, Exact sciences and technology, Sciences appliquees, Applied sciences, Industrie des polymeres, peintures, bois, Polymer industry, paints, wood, Technologie des polymères, Technology of polymers, Formes d'application et semiproduits, Forms of application and semi-finished materials, Fibres et fils, Fibers and threads, Sciences biologiques et medicales, Biological and medical sciences, Sciences medicales, Medical sciences, Chirurgie (generalites). Transplantations, greffes d'organes et de tissus. Pathologie des greffons, Surgery (general aspects). Transplantations, organ and tissue grafts. Graft diseases, Technologie. Biomatériaux. Equipements, Technology. Biomaterials. Equipments, Lactone polymère, Lactone polymer, Lactona polímero, Oside polymère, Oside polymer, Osido polímero, Propriété biologique, Biological properties, Propiedad biológica, Alginate, Alginates, Alginato, Biocompatibilité, Biocompatibility, Biocompatibilidad, Biomatériau, Biomaterial, Caprolactone polymère, Polycaprolactone, Caprolactona polímero, Charpente, Framework, Armadura, Cytodifférenciation, Cell differentiation, Diferenciación celular, Dimension pore, Pore size, Dimensión poro, Electrofilage, Electrospinning, Electrohilado, Etude expérimentale, Experimental study, Estudio experimental, Fabrication, Manufacturing, Fabricación, Génie tissulaire, Tissue engineering, Ingeniería de tejidos, Hydrophilie, Hydrophily, Hidrofilia, In vitro, Matériau poreux, Porous material, Material poroso, Morphologie, Morphology, Morfología, Multiplication cellulaire, Cell proliferation, Multiplicación celular, Mélange polymère, Polymer blends, Méthode couplée, Coupled method, Método acoplado, Nanofibre, Nanofiber, Nanofibra, Ostéoblaste, Osteoblast, Osteoblasto, Ostéogenèse, Osteogenesis, Osteogénesis, Polyélectrolyte, Polyelectrolyte, Polielectrolito, Porosité, Porosity, Porosidad, Propriété mécanique, Mechanical properties, Propiedad mecánica, Prototypage rapide, Rapid prototyping, Prototipificación rápida, Strut, 3D scaffold, and Composite

Micro/nanofibrous scaffolds have been used widely in biomedical applications because the micro/nanoscale fibres resemble natural extracellular matrix and the high surface-to-volume ratio encourages cellular activities (attachment and proliferation). However, poor mechanical properties, low controllability of various shapes and difficulties in obtaining controllable pore structure have been obstacles to their use in hard-tissue regeneration. To overcome these shortcomings, we suggest a new composite system, which uses a combination method of wet electrospinning, rapid prototyping and a physical punching process. Using the process, we obtained polycaprolactone (PCL)/alginate composite scaffolds, consisting of electrospun PCL/alginate fibres and micro-sized PCL struts, with mean pore sizes of 821 ± 55 μm. To show the feasibility of the scaffolds for hard-tissue regeneration, the scaffolds were assessed not only for physical properties, including hydrophilicity, water absorption, and tensile and compressive strength, but also in vitro cellular responses (cell viability and proliferation) and osteogenic differentiation (alkaline phosphatase (ALP) activity, and mineralisation) by culturing with pre-osteoblasts (MC3T3-E1 cells). With the reinforcing micro-sized PCL struts, the elastic modulus of the PCL/alginate scaffold was significantly improved versus a pure PCL scaffold. Additionally, due to the alginate component in the fibrous scaffold, they showed significantly enhanced hydrophilic behaviour, water absorption (~8-fold) and significant biological activities (∼1.6-fold for cell viability at 7 days, ∼2.3-fold for ALP activity at 14 days and ∼6.4-fold for calcium mineralisation at 14 days) compared with those of a pure PCL fibrous scaffold.

Polymers, paint and wood industries, Polymères, industries des peintures et bois, Sciences exactes et technologie, Exact sciences and technology, Sciences appliquees, Applied sciences, Industrie des polymeres, peintures, bois, Polymer industry, paints, wood, Technologie des polymères, Technology of polymers, Formes d'application et semiproduits, Forms of application and semi-finished materials, Matériaux composites, Composites, Sciences biologiques et medicales, Biological and medical sciences, Sciences medicales, Medical sciences, Chirurgie (generalites). Transplantations, greffes d'organes et de tissus. Pathologie des greffons, Surgery (general aspects). Transplantations, organ and tissue grafts. Graft diseases, Technologie. Biomatériaux. Equipements, Technology. Biomaterials. Equipments, Apatite hydroxylée, Hydroxyapatite, Hidroxiapatito, Biomatériau, Biomaterial, Copolymère aliphatique, Aliphatic copolymer, Copolímero alifático, Copolymère triséquencé, Triblock copolymer, Copolímero trisecuencia, Effet concentration, Concentration effect, Efecto concentración, Effet mémoire forme, Shape memory effect, Efecto memoria forma, Ethylène oxyde copolymère, Ethylene oxide copolymer, Etileno óxido copolímero, Etude expérimentale, Experimental study, Estudio experimental, Fabrication, Manufacturing, Fabricación, Forme cylindrique, Cylindrical shape, Forma cilíndrica, Génie tissulaire, Tissue engineering, Ingeniería de tejidos, Lactique acide copolymère, Lactic acid copolymer, Láctico ácido copolímero, Matériau composite, Composite material, Material compuesto, Matériau poreux, Porous material, Material poroso, Morphologie, Morphology, Morfología, Polymère amphiphile, Amphiphilic polymer, Polímero amfifilo, Propriété dynamomécanique, Dynamic mechanical properties, Propiedad dinamomecánica, Propriété mécanique, Mechanical properties, Propiedad mecánica, Prototypage rapide, Rapid prototyping, Prototipificación rápida, Tissu osseux, Osseous tissue, Tejido óseo, biodegradable, hydroxyapatite, rapid prototyping, shape-memory polymers, and tissue engineering

Biodegradable polymer/hydroxyapatite (HA) composites are desired for skeletal tissue engineering. When engineered with thermally responsive shape-memory properties, they may be delivered in a minimally invasive temporary shape and subsequently triggered to conform to a tissue defect. Here, the shape-memory properties of thermoplastic amphiphilic poly(D,L-lactic acid-co-ethylene glycol-co-D,L-lactic acid) (PELA) (Mw = 120 kDa) and HA-PELA composites are reported. These materials can be cold-deformed and stably fixed into temporary shapes at room temperature and undergo rapid shape recovery (<3 s) at 50 °C. Stable fixation (>99% fixing ratio) of large deformations is achieved at -20 °C. While the shape recovery from tensile deformations slows with higher HA contents, all the composites (up to 20 wt% HA) achieve high shape recovery (>90%) upon equilibration for 10 min at 50 °C. The permanent shapes of HA-PELA can be reprogrammed at 50 °C, and macroporous shape-memory scaffolds can be fabricated by rapid prototyping.

Biomedical engineering, Génie biomédical, Sciences biologiques et medicales, Biological and medical sciences, Sciences biologiques fondamentales et appliquees. Psychologie, Fundamental and applied biological sciences. Psychology, Biotechnologie, Biotechnology, Applications et implications industrielles. Aspects économiques, Industrial applications and implications. Economical aspects, Santé. Industrie pharmaceutique, Health. Pharmaceutical industry, Divers, Miscellaneous, Sciences medicales, Medical sciences, Chirurgie (generalites). Transplantations, greffes d'organes et de tissus. Pathologie des greffons, Surgery (general aspects). Transplantations, organ and tissue grafts. Graft diseases, Technologie. Biomatériaux. Equipements, Technology. Biomaterials. Equipments, Biomatériau, Biomaterial, Echafaudage, Scaffold, Andamiaje, Génie biomédical, Biomedical engineering, Ingeniería biomédica, Génie tissulaire, Tissue engineering, Ingeniería de tejidos, Os spongieux, Spongious bone, Hueso esponjoso, Perméabilité, Permeability, Permeabilidad, Propriété transport, Transport properties, Propiedad transporte, Prototypage rapide, Rapid prototyping, Prototipificación rápida, permeability, rapid prototyping, synthetic scaffold, tissue engineering, and trabecular bone

In this work, various three-dimensional (3D) scaffolds were produced via micro-stereolithography (μ-SLA) and 3D printing (3DP) techniques. This work demonstrates the advantages and disadvantages of these two different rapid prototyping methods for production of bone scaffolds. Compared to 3DP, SLA provides for smaller feature production with better dimensional resolution and accuracy. The permeability of these structures was evaluated experimentally and via numerical simulation utilizing a newly derived Kozeny-Carman based equation for intrinsic permeability. Both experimental and simulation studies took account of porosity percentage, pore size, and pore geometry. Porosity content was varied from 30% to 70%, pore size from 0.34 mm to 3 mm, and pore geometries of cubic and hexagonal closed packed were examined. Two different fluid viscosity levels of 1 mpa.s and 3.6 mPa.s were used. The experimental and theoretical results indicated that permeability increased when larger pore size, increased fluid viscosity, and higher percentage porosity were utilized, with highest to lowest degree of significance following the same order. Higher viscosity was found to result in permeabilities 2.2 to 3.3 times higher than for water. This latter result was found to be independent of pore morphology type. As well as demonstrating method for determining design parameters most beneficial for scaffold structure design, the results also illustrate how the variations in patient's blood viscosity can be extremely important in allowing for permeability through the bone and scaffold structures.