Knitectonics
Chapter V
Tectonics
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Model with 7 machines connecting into one perimeter
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The digital machinic system imparts us the opportunity to envision knitting as a principle of construction. The machine has a one to one relationship to the material result, as there is no manipulation involved in the process. In order to visualise it as a formal language for a programmable architecture, it was critical to explore the three dimensional and topological aspect of knitting. By definition, topological surfaces are smooth manifolds, so their construction should have no seams; this makes knitting a potential tool, with its continuous yarns interlocking to form complex surfaces. Historically, knitting has been a medium to explain mathematical ideas since the 19th century. The first models of knitted interpenetrating tubes were made by a Scottish chemistry Professor Alexander Crum Brown. 1 Until the 19th century, mathematicians knew about only two kinds of geometry: the Euclidean plane and the sphere. The discovery of hyperbolic space in the 1820s and 1830s marked a turning point in mathematics and initiated the formal field of non-Euclidean geometry. For more than a century, mathematicians searched in vain for a physical surface with hyperbolic geometry and starting in the 1950s, they began to suggest possibilities for constructing such surfaces. 2 Miles Reid in 1971 wrote a paper in which he described that a sphere, the torus and the Klein Bottle could be knit and gave the algorithm for the same. His motivation was to knit surfaces seamlessly, with minimal singularities and was even able to knit a projective plane. He then declared, ‘any topological surface can be knit. 3 Following this, in 1997, Prof. Daina Taimina, a mathematician at Cornell University, made the first useable physical model of the hyperbolic by using crochet, which has now extended to the hand craft of knitting.
Knitted Hyperbolic Planes. Prof. Daina Tamina, Cornell University.
Every topological surface, as a two- dimensional manifold, has a local coordinate system at each point. Knitting creates natural local coordinates in the form of rows and stitch columns. All knitting is the creation of global structure via choices made in the local stitch creation. 4 Thus, our digital system enables us to create a macro system of structure and a micro system of textures. We approached at developing a tectonic system, by realising the digital machinic system in terms of configurations, scale, size, resolution, layers, materials etc. 109
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Configurations : Grid The organization of hexagonal circle packing, gives six connection points to each machine. Within this grid, multiple machines could be arranged not just in a hexagonal configuration, but other linear and organic configurations to create tectonic elements or space variations depending on the size of the machines.
Hexagonal
Linear
Organic
Machine : Hierarchy Our aim is to address macro level and micro level issues with the knitting system, so it became imperative to introduce the idea of machine of variable sizes, such that the hierarchical tracks deal with the Hexagonal Hexagonal Linear Organic Hexagonal Linear Linear Organic macro issues of space and at the same time undertake the micro issues ofOrganic envelope.
configurations configurations configurations
configurations configurations configurations
configurations configurations configurations
Spatial / Envelope systems 6 points of connection
Single Machine
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Knitectonics Machine : Module Considering conventional construction as a starting point for the standard thickness of building envelopes used for structure and insulation, we calculated the desired thickness of the envelope to be 25 centimetres. We recognized from our analogue experiments that on tensioning, the cross- section of the knitted tube reduces by 30% – 35 %. It was vital to take this into account in determining the size of the machine. Hence, we deduced a diameter of 40 centimetres for the small machine. In hexagonal circle packing grid, each circle with a diameter of ‘d’ has six points of connection. Interestingly beyond this, only a circle of diameter of ‘9d’ on this grid has six connection points. So we inferred a diameter of 360 centimetres for the big machine, which would give us an appreciable spatial dimension after fabric tensioning.
Single Machine
Machine Hierarchy
Knitted Structure Floor plan at +0.20mts
Knitted Structure Floor Plan +2.00 mts Interior perimeter reduction 30%
Machine : Resolution The variable size machines are assembled together in the same hexagonal packing logic as a single size of machine. The small and the big machines, along with the voids of different dimensions created between them, give us an opportunity to employ them for envelopes, structural elements and service core and shafts, of varied resolutions.
Envelope
Structural Elements
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Services
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Tectonic Elements The proto system being a mono-system has the capacity to integrate multiple scales and resolutions and functions. The tectonic aspects are addressed at two levels by the system, firstly at the spatial or programmatic level, providing space, structure and punctures and secondly at the performative level, providing micro infrastructure, embedded services and performative skin. Spatial Variations The macro machine set up of tracks can be combined in a multitude of ways, as per the sequence of the yarn feeder movement, to attain a hierarchy of spaces. With the skin as the structure, we achieve continuous column free spaces that can connect and bifurcate to form networks and nodes. The structure is continuously embedded into the spatial envelopes to maintain integrity through continuity and connectivity. 3 Machines
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5 Machines
6 Machines
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Model with 7 machines connecting into one perimeter
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Columns The structural elements like columns could be fabricated using one or more small machines. The most basic one could be done with two machines, such that they connect and bifurcate as required in order to transfer the forces. As the elements created have no joints or seams, the forces are spread evenly across the shell without being concentrated on the joints, thus making it structurally efficient and lightweight. Additionally, material density could be controlled to counter higher loads at particular junctions.
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Apertures Opennings can be created using both the machine sizes, depending upon the size and purpose of the opening. Typically, dropping of a needle bed or track or a bridge, forms an opening in the envelope. Changing the routine by alternating between ‘sequence 0’ and ‘sequence 2’ i.e. continue and bridge or skipping a small machine while knitting, could also shape apertures. It is interesting to note, that ll the openings and punctures compute their own structure; by accumulation of material around them and also by the self regulation of knots with their inter relationality. 117
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Layering The combination of macro machines, the interstitial spaces between the macro machines and the micro machines, help configuring singular architectural elements and also multiple layers targeting multiple purposes. Various structural elements, namely the foundations, walls, columns, beams, and also circulation elements i.e. corridors, ramps become a part of the knit structure. The possibility of introducing a new material at any point of the process and directing it to a certain local or global path is to be used to embed services’ infrastructure, like water supply, electrical, heating, air conditioning, insulation, effortlessly into the layers.
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Materiality The skin is composed of three layers interlinked and sandwiched together, an exterior, an intermediate and an interior layer. Certain parts of the knit mesh are to be solidified, so material compatibility of fibre and hardener becomes of utmost importance. The interior layer, for the demands of structure and capacity of the deployment logic, is to be knitted with a pre-impregnated fibre and heat solidified with UV light. For high performance structure, carbon fibre is a possibility. Fibre optics and other energy harvesting fibres with photo luminescent pigments or flexible solar cells could also be included in the micro performative skin. Thus, the choreography of the way the material is deposited in the proto system, defines a new vocabulary for architecture, thus becoming a proto tectonic system. 119
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Topological connections and bifurcations
Linear double bed knitting machine
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Detail of layering model
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Along with designing tectonic elements, we understand the necessity of defining the three junctions of critical importance in all construction i.e. the detail at the junction of the structure to the ground, the detail at the connection of the envelope and intermediate slab and the detail at the roof.
Ground Connection For fixing to the ground, the knitted fabric would be sandwiched between thick steel rings –inner and outer, to counter compression. The profile of the rings would mirror the configurations of the knitting machines above. An appreciable depth of the knitted fabric would be sandwiched, as a foundation to the structure and also resist the tension caused by machines moving vertically upwards.
Slab The knitting system is basically a tension – dependent system and rigid floors could act as compressive elements. Our solution to retain the seamlessness of the structure while extending the capacity of an essentially vertical system into horizontal elements was to create beams connected to the envelope. We achieve these beams by dropping the fabric on the six needle beds of the big machine and knitting it to the outer envelope at the connection points to the small machines. In a setup of two or more big machines with surrounding smaller machines, the structural strength can be enhanced by knitting beams and cross beams. High performance 122
Knitectonics honeycomb sandwich panels that can withstand high compression loads can be used for flooring base. These panels are lightweight, thin (1cm thickness) and are made of glass or carbon fibre reinforced epoxy skins with a honeycomb core. 5 Additionally these can be cut to size at site. These honeycomb panels sit harmoniously in a fractal system of hexagonal geometry and the final flooring on this base can be of any select material. Model of interior perimeter beams
Roof
Honeycomb sandwich panel
The roof covering of the knitted structure entails another detail derived from textiles. A knot or a string pulled in knitwear, pulls together the rows of knots around it. Similarly, vertical face of the structure could converge into the horizontal roof, by tensioning from the loose end of the yarn. Mathematically, the area of the top of a cylinder equals the surface area of the side for height of radius/ 2. To gauge the length of soft fabric needed to form the roof, we add the elongation percent to the mathematical equation. This horizontal knitted mesh is held in place with a compression ring. The ring has a ‘U’ cross- section and works as roof drain, with roof slopes away from the centre. Drainage pipes placed in the voids of the envelope then carry this to the ground drainage systems. Model closing cylinder
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Materials The tectonic application of the digital system, required us to impart materiality to the system and also identify the on- site deployment procedure. Typically, architecture is associated with density, mass and permanence and textiles are believed to be light, vulnerable and impermanent. But today, high performance textiles or ‘technical textiles’ are amongst the most innovative fields of material research. Matilda Mc Quaid, curator of the exhibition ‘Extreme Textiles’ at the New York’s Cooper Hewitt Museum, addressed these in the article ‘Tectonics and Textiles’.6 She elaborates, ‘..pure function is their purpose, and success is determined by their ultimate performance. All exemplified by the highest standards of performance – stronger, lighter, faster, smarter, or safer.’
Carbon Fiber Sport Prothesis
Stronger Incredible strength is one advantage of many new textile fibres produced in the last century. The introduction of synthetic materials like nylon in the 1930s and polyester in the 1950s, which still form the bulk of the technical-textiles market today, marked an increase in strength over cotton. However, not until the 1960s, when carbon fibre and aramids (high-strength, fire-resistant polyamide fibres) such as Kevlar were introduced to speciality markets did a new era of high performance fibres begin. Combined with highly engineered textile structures, these ‘muscle’ fibres can now reinforce and lift hundreds of tonnes and withstand temperatures that can melt steel.
Pultruded Structural Member
Smarter Textiles are the natural choice for seamlessly integrating computing and telecommunications to create a more personal and intimate environment. Although fabrics are historically passive, garments of the 21st century will become more active participants in our lives, Embedded Fiber Optics
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automatically responding to our surroundings or quickly reacting to the information that the body transmits. For instance, an adjustable heated jacket has been developed by North Face in collaboration with Malden Mills and Soft Switch. Similarly, a transportable fabric environment, Zip Room synthesises design and technology to emphasise touch and adaptability. This three-dimensional textile has the capacity to generate and conduct low-voltage DC power, store and access digital information, and emit digital light. ‘Listener’, sense membrane_CITA
Additionally, one of the most far-reaching and innovative areas of textile and material science is nanotechnology – the manipulation of materials on the atomic level and is being extensively used in the field of medical textiles. Faster
Structural fibres for oil platforms
Faster implies a high-performance edge in various types of sporting equipment – cars, sailboats, racing sculls, and bicycles – which have all benefited from the combination of strength, rigidity and lightness attained in advanced composites. For example, carbon fibre composite, initially developed for the aerospace industry due to its lightness and rigidity, has created a revolution in sports and is often the material of choice for racing shells. Lighter
North Sails _ Competition boat sails
Advancements in fibre and textile engineering have created lighter, more durable and even functionally intelligent fabrics that make record breaking performances possible. Structural components have also benefited from textiles as engineers across all disciplines try to build with less material, less weight and in less time. More earthbound applications for composite structures include the construction of towers used to measure wind speeds and, in the future, possibly high-rise buildings in which to live and work.
BMW Concept Car
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The materials employed for our system would belong to three families: structural materials, infrastructural materials and performative materials.
Structural Fibres are knitted into soft fabric, but require a reinforcement material to form strong composite structures. In our initial research, we considered epoxy resin as a potential reinforcement material. But as the application of resin adds additional infrastructure to the process, has high drying time and high volatile solvent content, we looked at alternatives. The epoxy resin impregnated carbon fibre, merges the characteristics of both fibre and reinforcement into one and is thus ideal for knitting and solidifying for structural performance. The resin in the fibre gets activated by heat or ultraviolet radiation and has an appreciably lower setting time. Carbon Fiber + Resin _ Furniture
Another innovative fibre is the thermoform yarn, developed by a Belgian manufacturer of hi- tech monofilaments. This yarn can be knitted to shape and requires a temperature of 65 degree Celsius for a minute and gets stiff as it cools. On applying heat again, it can be reshaped to another form. Additionally, it can be combined with carbon fibre or Kevlar. Due to its low setting temperature, it is currently suitable for interior use and furniture. The manufacturers are on way to developing a fibre with higher setting temperatures and then thermoform could be a potential architectural material. The stiff structural segments of the envelope could thus use resin impregnated carbon fibre and the soft envelope could be knitted in the Gore tenara yarn and vapour sealed with silicone. The tenara yarn is a high strength fluoropolymer, with complete immunity to UV and weather and has high light transmission. Thermoform _ Luxilon
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Knitectonics Gore Tenara Yarn Outdoor Sculpture
Kevlar Wind Turbines
Carbon Laminate Composite Boeing 787 _ 50% of body
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Infrastructure Another systematic advantage of knitting is to create multiple systems of performance with a mono fabrication system. Hence infrastructure can be embedded into the structural and performative skin and layers. For instance, electric conductive wires and hydraulic systems could run in the envelope and provide electricity, heating, hot water etc. Another possibility is creating vertical gardens wherein knitted textiles made with geotextile fibres could form earth containers for plants and use embedded water supply pipes. For public installations and structures, the litmuscreen could indicate the pollution levels. This screen works like a lichen and indicates the acid/ base imbalance by shifting colours to indicate environmental pollutants, without using electricity.
Stiched pipe on textile
Knitted pipe conducting liquid
Flexible organic solar cells _ K&V
Pollution detector
Vertical garden
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Knitectonics Performative For sustainable and environmental reasons, we see potential in materials that can be ‘Grown in the fields’. The eco fibres could be derived from vegetables, plants, animals or minerals and the biological resins can be made with vegetable and plant oils, starch and also wood cellulose.
Biological resin
Wood cellulose
Fiber optics
Performative and smart techno- textiles are being extensively used in architecture and allied disciplines today. There are numerous smart fibres available, but we limited to the following for system application. Silicon optical fibres could be an efficient medium to transfer data and conduct light, as they reduce energy consumption. Fibre optics could be embedded to illuminate and achieve colour changing effects. And photo luminescent pigments could help create ambience responsive surfaces. Yet another pioneering material is the flexible organic cells, which can be inserted in a fibre. They retain the solar energy in the day and can convert it to emit it as light energy. These are made of conductive plastic materials like polymers and form an insulating layer. They can be customized in terms of energy density for buildings. An interesting application of these cells is the portable light project, designed by the Boston based architects Kennedy and Violich Architects. Each portable light is a simple, versatile textile with flexible photovoltaics and solid state lighting that can be adapted to local cultures and customized by people to traditional textile methods. Kennedy describes it as, ‘light can now be harvested, stored and carried in portable fabric surfaces’. 7 One instance is of making bags with these cells, which people carry in the day and allow the solar cells to retain energy and then use them as light source by the night.
Photo Luminescent Pigments_ K&V
Portable light project _ K&V
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Carbon fiber and epoxy resin detail
Pre-Impregnated carbon fiber
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“By marrying high performance fibers with a polymeric matrix, both the low mechanical properties of unreinforced polymers and the poor compressive strength of unbounded fibers essentially disappear, as does the inherent brittleness and weakness of each ingredient. In ancient times and also in military applications the main rationale for implementing composite was, and still is, performance improvement” Adriaan Beukers and Ed van Hinte ‘Flying Lightness’
Boeing 787 detail of body section (50% Carbon laminate composites)
Fibres Composites A feasible and efficient material composite system is the one which one arrives at the final product through minimum materials or ‘ingredient’ and has a limited number of steps in its production process. Polymeric composites, in comparison to traditional materials, offer improved structural performance per unit weight and cost. We chose fibre composites as they facilitate us in achieving lightweight and strong knitted structures, with their ultra high massspecific stiffness. There application as the material to make aircraft fuselage, propellers, Formula 1 cars and other hi- tech high performance purposes illustrates their strength. Most of these applications, for their fibre structures, use familiar methods such as winding, weaving, braiding, stitching and interloping. These fibre performs can be impregnated with matrix material before, during or after assembly. Prepreg fibers i.e. thermosetting pre impregnated fibers could be employed in this process, by knitting a yarn with thermosetting properties. When heat is applied to these fibers, the process of catalysis is initiated and the resin ‘freezes’ in a desired form. Prepregs are mass produced in factories and require only heating or UV equipment on-site.
The selection of the appropriate fibre type typically depends on the application and design. Comparing the engineering constants of different yarns – carbon fibre, glass fibre and steel fibre – carbon fibre has the lowest density i.e. weight per cubic meter (1/4th of steel fibre) making it lightweight and has highest young’s modulus i.e. stress per square meter (3 times higher than glass fibre) making it ultra stiff. This indicates high structural efficiency i.e. extraordinary capability to carry load per unit mass, deeming it fit for the architectural application envisioned with our machinic system. 131
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Solidification in 3 Stages
Only tension
50% Solidified
Only tension
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75% Solidified
Only tension
100% Solidified
Tension variation before and after progressive solidification with resin
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Solidification After knitting the prepreg carbon fibre, solidification is the next important material process to be followed during the deployment process. The machines have two rings, the upper one for knitting prepreg carbon fibres and the one below with UV light, to solidify the knitted structure. The UV gets activated and the time taken depends on the density, thickness and conductivity of the resin. Also the cooling rate has to be carefully controlled to avoid thermal stresses. The distance between the two rings and the diameter of the solidification ring were determined by doing analogue tests. The test was done in three phases with two parameters i.e. the fixing diameter (D) and the stretched length of knitted fabric (L). In the first phase, the diameter is equal to the length and hence gives a constantly changing cross- section, but this cross- section is symmetrical about the centre at half the diameter. For the next phase, the stretched length equals twice the diameter and interestingly, a dimension equal to half the diameter on each end has a changing cross- section and the length in between has a constant cross- section. In the last phase, the stretched length equals three times the diameter and reinforces the cross- sectional results obtained earlier. Thus, facilitating us to determine the distance between the knitting and the UV ring; this is to be equal to half the diameter. The analogue test also reinforces the idea of stretching and solidifying in phases, contrary to the idea of solidifying in the end of the knitting and stretching process. 134
Pre-Peg knitted fibers
UV curing (manual equipment)
Instant resin UV curing
Knitectonics 30 Machines (Dia. 40 cms)
Space Machine (Dia. 3,60 mts)
Sliding Tube
Primary Structure
UV Lighting Solidification Ring
Pre-Preg Carbon Fiber + Epoxy Resin
Machine axonometric section
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Machine set up
Deployment The site constraints and programmatic needs determine the most favourable deployment technique for a particular scenario, depending on different attributes i.e. the scale, resolution, richness of the topological space created and volumetric possibilities. Though for our first machine prototype we had considered both vertical and horizontal deployment, with the final prototype of multiple modular machine we limited ourselves to the vertical deployment. Horizontal deployment was discarded due to the cumbersome setup and infrastructure, necessitated by the extraordinary amount of tension The site constraints and programmatic needs determine the most favourable deployment technique for a particular scenario, depending on different attributes i.e. the scale, resolution, richness of the topological space created and volumetric possibilities. The deployment process is to be executed in the following stages: Firstly, the machine is placed on its location by a construction crane, a certain height above the ground. The machine then knits and lets the knitted fabric fall with gravity, which is attached to the ground. Attachment The knitted fabric can be attached directly to the ground. The initial process for this set up is the fixing
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Solidification
Vertical movement + Knitting started
of the knitted dense foundations to attachment rings and then filled with compact mortar. This solid base then becomes the support for the whole structure. All the machines in the configuration could be initiated either at the onset of the process, or alternately the perimeter machines could be activated at later stages of the process. Activating tracks in later stages implies setting up a scaffolding, at the new point of attachment required by the design, after all the tracks have moved forth a certain distance. The geometry of the attachment ring and the scaffolding is a replica of the machine configuration i.e. hexagonal close packing. Each machine track would have a corresponding steel ring on the attachment, allowing a clamped connection. It is also important to evaluate and consider the possibility of using adjacent structures or site features, where the system can be anchored without disruption the surroundings. This method could have great potential in dense urban areas, sites with sloping topographies or vertical natural features, creating design solutions that adapt and respond to on-site parameters. Movement The vertical machine movement is a synchronized process, with all the machines. The movement will be determined by the site and the size of the building. For small and medium deployments a temporary 137
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structural portal not exceeding seven meters on the vertical plane could be used for constrained sites. For large applications, the movement will be provided by a construction crane. Solidification The process of solidification is crucial, as the already solidified parts of the structure become a structural support to reduce the tensioning of the system. The structural material is knitted in the inner core of the structures; using heat activating ‘prepregs’- pre-impregnated carbon fibres with a resin matrix, to avoid contamination of the site or other performative fibres with resins. In order to activate these pre impregnated fibres, a ring parallel to the track would hold UV lighting devices. As the circular track knits the structure, the curing ring activates the pre-impregnated fibres structural properties. Termination When the machines end its knitting cycle, process can be terminated in two ways, either by retracting the UV lighting ring to solidify the last section. After curing this section, the knots are tied together and the final knots are released from the machine. The second way is to leave the last section of the knitted structure as a soft surface and then enclose the termination. The deployment possibilities of the on-site knitting system make the system flexible and adaptable to various scenarios and sites.
Notes for Chapter V 1.Daina Taimina , ‘Crocheting Adventures with Hyperbolic Planes’, AK Peters Ltd., Wellesley, MA (2009) page 66 2.http://www.cabinetmagazine.org/issues/16/crocheting.php 3.Sarah- Marie Belcastro, ‘Every topological surface can be knit: a proof’, Journal of Mathematics and the Arts, 1751-3480, Volume 3, Issue 2, 2009,page 71 4.Ibid, page 73 5.http://www.lusas.com/case/composite/floorpan.html 6. McQuaid, Matilda, “Tectonics and Textiles”, Architectural Design ‘Architextiles’, Vol. 76 No 6, John Wiley and Sons, England (2005) 7. http://www.kvarch.net/
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Frozen Fibers S a n h i t a C h a t u r v e d i [India] E s t e b a n C o l m e n a r e s [Colombia] T h i a g o M u n d i m [Brazil]
Tutors
Marta MalĂŠ-Alemany Jeroen van Ameijde Daniel Piker
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Machinic Control 2.0 Design Research Lab v13 Archit ectural Association London Phase II Copyright Š Frozen Fibers 2011, otherwise indicated and used only for academic purposes.