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Nature offers a marvel of astonishing and rich deformation behaviors. Yet, most of the objects we fabricate are comparatively rather inexpressive, either rigid or exhibiting simple homogeneous deformations when interacted with. We explore the synthesis and fabrication of novel microstructures that mimic the effects of having oriented rigid fibers in an otherwise flexible material: the result is extremely rigid along a transverse direction while being comparatively very flexible in the locally orthogonal plane. By allowing free gradation of the rigidity direction orientation within the object, the microstructures can be designed such that, under deformation, distances along fibers in the volume are preserved while others freely change. Through a simple painting tool, this allows a designer to influence the way the volume reshapes when deformed, and results in a wide range of novel possibilities. Many gradations are possible: local free orientation of the fibers; local control of the overall material rigidity (structure density); local canceling of the effect of the fibers, obtaining a more isotropic material. Our algorithm to synthesize the structures builds upon procedural texturing. It produces a cellular geometry that can be fabricated reliably despite 3D printing walls at a minimal thickness, allowing prints to be very flexible. The synthesis algorithm is efficient and scales to large volumes.

International audience; In this paper, we propose to use new 3D-printed meso-structured materials to build soft robots and we present a modeling pipeline for design assistance and control. These meta-materials can be programmed before printing to target specific mechanical properties, in particular heterogeneous stiffness and anisotropic behaviour. Without changing the external shape, we show that using such meta-material can lead to a dramatic change in the kinematics of the robot. This highlights the importance of modeling. Therefore, to help the design and to control soft robots made of these meso-structured materials, we present a modeling method based on numerical homogenization and Finite Element Method (FEM) that captures the anisotropic deformations. The method is tested on a 3 axis parallel soft robot initially made of silicone. We demonstrate the change in kinematics when the robot is built with meso-structured materials and compare its behavior with modeling results.

International audience; Additive manufacturing is typically conducted in a layer-by-layer fashion. A key step of the process is to define, within each planar layer, the trajectories along which material is deposited to form the final shape. The direction of these trajectories triggers an anisotropy in the fabricated parts, which directly affects their properties, from their mechanical behavior to their appearance. Controlling this anisotropy paves the way to novel applications, from stronger parts to controlled deformations and surface patterning.This work introduces a method to generate trajectories that precisely follow an input direction field while simultaneously avoiding intra- and inter-layer defects. Our method results in spatially coherent trajectories - all follow the specified direction field throughout the layers - while providing precise control over their inter-layer arrangement. This allows us to generate a staggered layout of trajectories across layers, preventing unavoidable tiny gaps from forming tunnel-shaped voids throughout a part volume.Our approach is simple, robust, easy to implement, and scales linearly with the input volume. It builds upon recent results in procedural generation of oscillating patterns, generating a signal in the 3D domain that oscillates with a frequency matching the deposition beads width while following the input direction field. Trajectories are extracted with a process akin to a marching square.

Le passage dévastateur de l’ouragan Sandy sur la côte est américaine en octobre 2012 est apparu comme un levier pour repenser l’aménagement des berges en vue de se préparer à la récurrence inévitable d’autres tempêtes extrêmes. Ne pouvant être relevés que par l’innovation, les défis posés par les changements climatiques ont incité le gouvernement fédéral à lancer le concours international Rebuild by Design dans l’objectif de développer des stratégies adaptatives se distinguant des mesures de protection rigides habituellement préconisées. Nécessitant une évolution conséquente des modes de planification, une vaste démarche de conception intégrée impliquant les équipes finalistes et des acteurs de différents horizons a été mise en branle. Parmi les projets phares retenus figurent la Dryline et son parc éponge. Ce système de protection intégré destiné à rendre la pointe sud de l’île de Manhattan résiliente aux inondations a contribué à dessiner les contours d’une approche audacieuse basée sur une plus grande accommodation de l’eau en milieu fortement urbanisé, jusqu’à ce qu’un lot de contraintes locales enclenche un retour vers une stratégie de gestion de risques plus traditionnelle., The devastating passage of hurricane Sandy, on the American eastern coast in October 2012, appeared like an opportunity to redesign the shore layout in view of preparing for an inevitable recurrence of other extreme storms. Since taking up this challenge could only be done by innovation, the challenges brought on by climate changes prompted the federal government to launch the Rebuild by Design international contest, with the objective of developing adaptive strategies that distinguish themselves from the rigid protection measures commonly recommended. Since this required evolution consistent with the planning methods, a vast integrated design undertaking was launched involving finalist teams and actors from different backgrounds. Amongst the leading projects selected were Dryline and its water retention park. This integrated protection system, intended to make the southern end of Manhattan Island resilient to floods, contributed to designing the structure of an of an audacious approach. This approach is based on larger water accommodation capacity in a heavily urbanized environment, up to when a number of local constraints triggers returning to a more traditional risk management strategy.

La diffusion des ateliers de fabrication numérique (AFN) est devenue un phénomène mondialisé. Principalement localisés en milieu urbain, ces ateliers ont la volonté de mettre à la disposition des citadins des moyens de production afin de concevoir, de réparer et de prototyper toutes sortes d’objets. Depuis quelques années, nous avons constaté un enthousiasme croissant des pouvoirs urbains pour ces pratiques popularisées par le mouvement maker. L’objectif de cet article est de comprendre les relations qu’entretient ce phénomène avec les gouvernements urbains. Peu de choses ont été écrites sur la façon dont les villes mettent en oeuvre des stratégies pour encourager ces pratiques sur leur territoire. Pour combler cette lacune, nous avons analysé le cas de la ville de Barcelone, qui mène une action territoriale ambitieuse à travers la création d’un réseau public d’ateliers dédiés à la fabrication numérique., The spread of makerspaces has become a global phenomenon. Mainly located in urban areas, these spaces provide urban dwellers with means of producing, designing, repairing and prototyping all kinds of objects. Since a few years, we have seen growing enthusiasm with urban powers for the maker movement practices. The objective of this article is to help understand the relationships between this phenomenon and urban institutions. Little has been written on how cities are implementing strategies to promote these practices. Thus, we here analyze the case of the city of Barcelona that is conducting an ambitious territorial operation by creating a public network of places dedicated to digital fabrication.

Up until today, the technology used for the capture and production of pure CO 2 in post-combustion applications for both use and sequestration relies primarily on the use of chemical amine solvents such as monoethanolamine (MEA). However, these solvents require significant amounts of valuable, high-grade process heat for solvent regeneration and suffer from substantial operational and environmental issues including degradation, toxic aerosol emissions, sensitivity to flue gas contaminants, and corrosivity. CO 2 Solutions Inc (CSI) recently developed and deployed a new technology to solve these challenges by employing a non-toxic low-cost, stable salt solution as an absorption solution and the carbonic anhydrase enzyme as a catalyst for carbon management. The result is both fast CO 2 absorption kinetics and significantly reduced energy costs by allowing to use low-grade heat to drive the solution regeneration. This study aims to analyze and compare the environmental profile of capture processes such as CSI, MEA and UNO MK3 (a precipitating potassium carbonate separation process). The context of the study is CO 2 capture from the flue gas stream of a 550 MW coal-fired power station in the midwestern USA. To fulfill the objective, we performed an attributional cradle-to-gate LCA comparing the three systems. This study was conducted according to the requirements of ISO 14040 & 14044 and reviewed by an independent panel which concluded that “The LCA requirements of ISO 14040 and ISO 14044 have been answered in the best possible manner.” Data were mainly based on process simulation of the three technologies. The impact assessment was carried out with the Impact 2002+ method. This method considers four indicators at endpoint level ( Climate change, Human health, Ecosystem quality and Resources) and sixteen indicators at midpoint level (for instance Aquatic Acidification or Ozone formation). Results show that the CSI carbon capture unit has significantly lower potential impacts than the MEA and UNO MK3 units. The CSI system presents lower scores than the MEA and the UNO MK3 systems for all midpoint and endpoint indicators. The operation stage, and more especially its energy consumption, is the main contributor to the environmental profile of all three systems. The CSI system differs radically from the MEA and UNO MK3 systems as it can use hot water instead of steam for its regeneration step. Hot water is a waste from the power plant, whereas steam consumption reduces the production of electricity at the power plant, which needs to be compensated elsewhere. In this study, it is considered that these losses of electricity production will affect the regional market in which the power plant is located, and therefore the lost electricity is produced by an average electricity grid mix coming from this regional market. Other inputs do not contribute significantly to the environmental profile of the systems at endpoint level. Among them, chemical inputs are the top contributors. However, the midpoint category where CSI technology differentiates itself the most from other technologies is when comparing the MEA Respiratory Organics score, which is 3.5 times higher than CSI. The several sensitivity analysis conducted typically do not affect the conclusion.

Additive manufacturing techniques form an object by accumulating layers of material on top of one another. Each layer has to be supported by the one below for the fabrication process to succeed. To reduce print time and material usage, especially in the context of prototyping, it is often desirable to fabricate hollow objects. This exacerbates the requirement of support between consecutive layers: standard hollowing produces surfaces in overhang that cannot be directly fabricated anymore. Therefore, these surfaces require internal support structures. These are similar to external supports for overhangs, with the key difference that internal supports remain invisible within the object after fabrication. A fundamental challenge is to generate structures that provide a dense support while using little material. In this paper, we propose a novel type of support inspired by rib structures. Our approach guarantees that any point in a layer is supported by a point below, within a given threshold distance. Despite providing strong guarantees for printability, our supports remain lightweight and reliable to print. We propose a greedy support generation algorithm that creates compact hierarchies of rib-like walls. The walls are progressively eroded away and straightened, eventually merging with the interior object walls. We demonstrate our technique on a variety of models and provide performance figures in the context of Fused Filament Fabrication (FFF) 3D printing.

International audience; We propose a method to simultaneously decompose a 3D object into power diagram cells and to integrate given functions in each of the obtained simple regions. We offer a novel, highly parallel algorithm that lends itself to an efficient GPU implementation. It is optimized for algorithms that need to compute many decompositions, for instance, centroidal Voronoi tesselation algorithms and incompressible fluid dynamics simulations. We propose an efficient solution that directly evaluates the integrals over every cell without computing the power diagram explicitly and without intersecting it with a tetrahedralization of the domain. Most computations are performed on the fly, without storing the power diagram. We manipulate a triangulation of the boundary of the domain (instead of tetrahedralizing the domain) to speed up the process. Moreover, the cells are treated independently one from another, making it possible to trivially scale up on a parallel architecture. Despite recent Voronoi diagram generation methods optimized for the GPU, computing integrals over restricted power diagrams still poses significant challenges; the restriction to a complex simulation domain is difficult and likely to be slow. It is not trivial to determine when a cell of a power diagram is completely computed, and the resulting integrals (e.g. the weighted Laplacian operator matrix) do not fit into fast (shared) GPU memory. We address all these issues and boost the performance of the state-of-the-art algorithms by a factor 2 to 3 for (unrestricted) Voronoi diagrams and a ×50 speed-up with respect to CPU implementations for restricted power diagrams. An essential ingredient to achieve this is our new scheduling strategy that allows us to treat each Voronoi/power diagram cell with optimal settings and to benefit from the fast memory.

International audience; Nowadays, we can observe a multiplication of multi-view data in domains such as marketing, bank administration, survey analysis, or social networks: We are dealing with large data bases that share a fair amount of data representing the same individual with different features depending on the data base. In this context, one can use Machine Learning methods to analyze this fragmented data across several heterogeneous sources (called views). Such analysis is subject to several difficulties: First, not all individual will be present and represented in all data sites and views. And second, this type of cross site analysis raises several ethical questions on privacy issues as no local site should have direct access to data from the other sources. To solve these problems, we present a method called the Cooperative Reconstruction System which aims at reconstructing information missing in some views in a multi-view context using information available in the other views. Furthermore, our method considers privacy issues and therefore achieves said reconstruction without direct data transfer from one view to another.

In most layered additive manufacturing processes, a tool solidifies or deposits material while following pre-planned trajectories to form solid beads. Many interesting problems arise in this context, among which one concerns the planning of trajectories for filling a planar shape as densely as possible. This is the problem we tackle in the present paper. Recent works have shown that allowing the bead width to vary along the trajectories helps increase the filling density. We present a novel technique that, given a deposition width range, constructs a set of closed beads whose width varies within the prescribed range and fill the input shape. The technique outperforms the state of the art in important metrics: filling density (while still guaranteeing the absence of bead overlap) and trajectories smoothness. We give a detailed geometric description of our algorithm, explore its behavior on example inputs and provide a statistical comparison with the state of the art. We show that it is possible to obtain high quality fabricated layers on commodity FDM printers.

We present a method for effectively planning the motion trajectory of robots in manufacturing tasks, the tool paths of which are usually complex and have a large number of discrete time constraints as waypoints. Kinematic redundancy also exists in these robotic systems. The jerk of motion is optimized in our trajectory planning method at the meanwhile of fabrication process to improve the quality of fabrication. Our method is based on a sampling strategy and consists of two major parts. After determining an initial path by graph search, a greedy algorithm is adopted to optimize a path by locally applying adaptive filers in the regions with large jerks. The filtered result is obtained by numerical optimization. In order to achieve efficient computation, an adaptive sampling method is developed for learning a collision-indication function that is represented as a support-vector machine. Applications in robot-Assisted 3-D printing are given in this article to demonstrate the functionality of our approach. Note to Practitioners-In robot-Assisted manufacturing applications, robotic arms are employed to realize the motion of workpieces (or machining tools) specified as a sequence of waypoints with the positions of tool tip and the tool orientations constrained. The required degree of freedom (DOF) is often less than the robotic hardware system (e.g., a robotic arm has six-DOF). Specifically, rotations of the workpiece around the axis of a tool can be arbitrary (see Fig. 1 for an example). By using this redundancy, i.e., there are many possible poses of a robotic arm to realize a given waypoint, the trajectory of robots can be optimized to consider the performance of motion in velocity, acceleration, and jerk in the joint space. In addition, when fabricating complex models, each tool path can have a large amount of waypoints. It is crucial for a motion planning algorithm to compute a smooth and collision-free trajectory of robot to improve the fabrication quality. The time taken by the planning algorithm should not significantly lengthen the total manufacturing time; ideally, it would remain hidden as computing motions for a layer can be done while the previous layer is printing. The method presented in this article provides an efficient framework to tackle this problem. The framework has been well tested on our robot-Assisted additive manufacturing system to demonstrate its effectiveness and can be generally applied to other robot-Assisted manufacturing systems.

The purpose of this study is to present the current state of scientific knowledge on the Winter Olympic Games (2000 to present-day) and their urban and tourism-related impacts. To achieve this, a scoping review was performed using established methodology. Of the 1694 English and French peer-reviewed sources identified from 14 different databases, 47 met the specific inclusion criteria and were retained for analysis. Findings were divided into three sections according to our objectives: (1) methodological profiles of the selected articles; (2) urban impacts; (3) tourism-related impacts. First, the reviewed sources – mainly qualitative – generally showed that mega-events such as the Winter Olympic Games are a catalyst for the urban renewal of host cities. However, these urban transformations must be part of a global scenario to ensure long-term viability. Although research shows that the Games represent an opportunity for the development of the tourism industry, the scoping review showed mixed resul...

CO 2 Solutions Inc. of Quebec, Canada has commercialized a proprietary low-cost, enzyme accelerated solvent technology for the capture of carbon dioxide and its beneficial reuse. Enzyme catalyzed aqueous salt solutions can be deployed with a variety of gas scrubbing equipment configurations to replace costly and environmentally challenged amines solvents as an efficient solution for post-combustion CO 2 capture. The presentation will discuss the results of its 10 tonne-CO 2 /day demonstration carried out in the summer and fall of 2015 in Salaberry-de-Valleyfield (“Valleyfield), near Montreal, Canada. The Valleyfield project was the largest-ever scale test of an enzyme-based CO 2 capture process and used an industrially robust form of carbonic anhydrase enzyme developed by CO 2 Solutions to capture CO 2 from a natural gas fired boiler. The demonstration operated successfully for a total of more than 2,500 hours and saw stable performance of the enzyme catalyst, stable solvent performance with negligible degradation, no wastes generated, and highly pure CO 2 produced suitable for a broad range of reuse applications. In addition, the use of low-grade, nil-value heat for solvent regeneration at low temperature was accomplished, demonstrating this innovative method of operating cost savings. The presentation will include performance aspects of the demonstration and associated techno-economics of the technology for application to electricity and steam generation. An update on the technology's commercial implementation will also be provided.

International audience; Slicing is the procedure necessary to prepare a shape for layered manufacturing. There are degrees of freedom in this process, such as the starting point of the slicing sequence and the thickness of each slice. The choice of these parameters influences the manufacturing process and its result: The number of slices significantly affects the time needed for manufacturing, while their thickness affects the error. Assuming a discrete setting, we measure the error as the number of voxels that are incorrectly assigned due to slicing. We provide an algorithm that generates, for a given set of available slice heights and a shape, a slicing that is provably optimal. By optimal, we mean that the algorithm generates sequences with minimal error for any possible number of slices. The algorithm is fast and flexible, that is, it can accommodate a user driven importance modulation of the error function and allows the interactive exploration of the desired quality/time tradeoff. We demonstrate the practical importance of our optimization on several three-dimensional-printed results.

We propose a method for integrated tool path planning and support structure generation tailored to the specific constraints of extrusion-based ceramics printing. Existing path generation methods for thermoplastic materials rely on transfer moves to navigate between different print paths in a given layer. However, when printing with clay, these transfer moves can lead to severe artifacts and failure. Our method eliminates transfer moves altogether by generating deposition paths that are continuous within and across layers. Our algorithm is implemented as a sequential top-down pass through the layer stack. In each layer, we detect points that require support, connect support points and model paths, and optimize the shape of the resulting continuous path with respect to length, smoothness, and distance to the model. For each of these subproblems, we propose dedicated solutions that take into account the fabrication constraints imposed by printable clay. We evaluate our method on a set of examples with multiple disconnected components and challenging support requirements. Comparisons to existing path generation methods designed for thermoplastic materials show that our method substantially improves print quality and often makes the difference between success and failure.

Procedural pattern synthesis is a fundamental tool of Computer Graphics, ubiquitous in games and special effects. By calling a single procedure in every pixel - or voxel - large quantities of details are generated at low cost, enhancing textures, producing complex structures within and along surfaces. Such procedures are typically implemented as pixel shaders. We propose a novel procedural pattern synthesis technique that exhibits desirable properties for modeling highly contrasted patterns, that are especially well suited to produce surface and microstructure details. In particular, our synthesizer affords for a precise control over the profile, orientation and distribution of the produced stochastic patterns, while allowing to grade all these parameters spatially. Our technique defines a stochastic smooth phase field - a phasor noise - that is then fed into a periodic function (e.g. a sine wave), producing an oscillating field with prescribed main frequencies and preserved contrast oscillations. In addition, the profile of each oscillation is directly controllable (e.g. sine wave, sawtooth, rectangular or any 1D profile). Our technique builds upon a reformulation of Gabor noise in terms of a phasor field that affords for a clear separation between local intensity and phase. Applications range from texturing to modeling surface displacements, as well as multi-material microstructures in the context of additive manufacturing.

The improvement of automated resource management techniques for cloud computing platforms requires a deep understanding of the workload. Previous works focused on virtual machines (VMs), and neglected complementary virtual resources such as images, volumes, snapshots and security groups. Besides, most attention went to public hyperscale platforms with more than ten thousand servers, or small on-premise platforms. To fill the gap, we perform a holistic workload characterization of a non-hyperscale platform. We have collected a three-month-long trace allowing us to characterize the correlated utilization of virtual resources; the consumption of CPU, memory and disk by VMs; and the CPU interferences between VMs.