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1

Lethbridge, Alfred John. "Bio-inspired optical systems." Thesis, University of Exeter, 2013. http://hdl.handle.net/10871/14727.

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This thesis presents an investigation into some of the structural colours that are produced in nature. There are many animals and plants that produce structural colour, with a particularly high structural colour diversity in insects. Of the species that exhibit structural colours, three species are the subjects for investigation of this thesis. Those comprise a group of beetles from South-East Asia, Torynorrhina flammea, a buttery, Parides sesostris and a fruit, Margaritaria nobilis, both from South American rainforests. The structures that produce the vivid colours of these species were analysed using electron microscopy. This information aided the design and creation of three inorganic, synthetic replicas of the natural structures. The fruit of Margaritaria nobilis was structurally analysed, yielding the discovery of a novel multilayer fibre. These fibres were cylindrical in design and were found to be layered together producing the epidermis of the fruit. The multilayer structure produced a vivid blue colour appearance, which is believed to offer a selective advantage because the colour deceives birds into thinking that the fruit contains nutritious flesh. This selective advantage earns M. nobilis the label of mimetic fruit. The structure found within the M. nobilis fruit epidermis inspired the synthesis of a structure which comprises single cylindrical multilayer fibres. The synthetic fibres were manufactured from elastic materials which allow the structure to be deformed under strain and, therefore, a change in colour can be observed. As the structure was stretched, this made the layers get thinner and, therefore, the colour of the fibre blue-shifted. The fibre was able to be stretched to over twice its original length which yields a shift in peak reflected wavelength of over 200 nm. Four beetles from the Torynorrhina flammea species were investigated with the aim of replicating the nanostructures responsible for their colour appearance. The initial interest in the beetles came from their strikingly vivid colour appearances. The structure responsible for the vivid colours in all four of the subspecies is a multilayer with high structural order and over 100 laminae. Both of these attributes contribute to the saturation of the colours exhibited. The multilayer was found to be intersected by an array of rods, the long axis of which is orthogonal to the surface. The rods are believed to be the cause of an interesting diffraction phenomenon exhibited by the beetles. Using imaging scatterometry, the structure was found to diffract the colour produced by the multilayers into an annulus around a specularly reflected white spot. This inspired the synthesis of a multilayer permeated with an array of holes with the aim of replicating a system that could reproduce the annular pattern of colour reflection. The initial synthesised system comprised a quarter-wave stack with a perfectly ordered hexagonal array of holes permeating the surface orthogonally. The sample displayed the scattering characteristics of a hexagonal array, and the reflection spectra of the multilayer stack. When disordered hexagonal arrays were milled into the structure with a focussed ion beam, the scattering pattern started to show more of the green colour from the multilayer and less of the ordered scattering pattern. The highly disordered, synthesised structure displayed no hexagonal scattering pattern, but instead it showed a highly scattered bluish-green colouration. One sample was created by directly mapping out the array of holes using an image of the original array from one of the beetle samples. This sample was expected the same annular diffraction pattern as the beetles, however, the sample instead exhibited the same scattering pattern as the highly disordered array. Some structurally coloured systems in nature have more than one light scattering structure, all of which contribute to the overall colour of the system. For complicated systems such as this, it is necessary to devise a technique to characterise the individual scattering structures separately. One such species that displays a complex, multicomponent system is Parides sesostris. The male of the species displays bright green patches on the dorsal side of the forewings which are made up of thousands of green wing scales. These green scales contain a 3D gyroid poly-crystal at centre with a membrane layer surrounding the underside of each scale and a scattering structure on top. Using focussed ion beam milling techniques allowed the individual characterisation of each of these structures. The gyroid poly-crystal was found to reflect not green but blue wavelengths. This led to the discovery by another group [1] that the scales contain at least one type of fluorophore. The removal of the membrane structure and some of the gyroid poly-crystal from the base of the scale resulted in the change of the overall scale structure from green to cyan. This suggests that the membrane maybe a significant source of fluorescence. Computational modelling, without fluorescence, suggests that the addition of the membrane layer to the gyroid does not shift the band-gap wavelengths; however, the overall reflection intensity does increase. The scattering structure on the top side of each scale is comprised a bi-grating which sits on top of the 3D gyroid structure. The long periodicity of the bi-grating protrudes above the surface, resulting in the very top layer of the scale to be a mono-grating. This whole structure decreases the angular-dependence of the colour by efficiently scattering the incident light into the gyroid and also scattering the reflected light from the gyroid, resulting in a double-scattering. FIB-milling was used to isolate the scattering part of the structure. Analysis of this component of the structure revealed that it was not a source of the green colour itself; however, it did show the characteristic scattering pattern of a mono-grating. The small periodicity of the bi-grating did not produce a scattering pattern since the periodicity is too small to produce optical diffraction at normal incidence. To characterise the effect of the fluorophores, the whole scale structure was photo-bleached using ultra-violet radiation for two months with the aim of destroying the fluorophores contained within the structure. The expected result occurred which was the blue-shifting of the peak reflected wavelengths. However, it could not be confirmed whether or not the photo-bleaching reduced the physical size of the light scattering structures which would, in theory, result in a blue-shift of the peak reflected wavelengths. The male P. sesostris green wing scales were also the subject for investigation for trying to make inorganic replicas of the gyroid-polycrystal. A surface sol-gel coating process was utilised to coat the green wing scales with titania. This coating process was performed using a few different methods. Half of the samples were coated with TiO2 and the other half with tin-doped TiO2. Half of each of these samples had their surfaces dendritically amplified before the coating processes and the other half were left untreated. The samples were coated with 25 surface sol-gel (SSG) cycles of each treatment at a time. After each 25 cycle treatment the samples were optically characterised. The total number of cycles applied to the samples at the end was 150. The addition of layers of titania resulted in a general red-shift that was higher for the tin-doped titania samples than for the titania samples. Another general trend found was that the samples that had their surfaces dendritically amplified, produced a lower red-shift in peak wavelength. This was contrary to the hypothesis that the amplification process was supposed to aid the SSG coating process and, therefore, increases the red-shift in peak wavelength.
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2

Gonos, Theophile. "Bio-inspired adaptive sensing." Thesis, University of Edinburgh, 2012. http://hdl.handle.net/1842/6217.

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Sensor array calibration is a major problem in engineering, to which a biological approach may provide alternative solutions. For animals, perception is relative. The aim of this thesis is to show that the relativity of perception in the animal kingdom could also be applied to robotics with promising results. This thesis explores through various behaviours and environments the properties of homeostatic mechanisms in sensory cells. It shows not only that the phenomenon can solve partial failure of sensors but also that it can be used by robots to adapt to their (changing) environment. Moreover the system shows emergent properties as well as adaptation to the robot body or its behaviour. The homeostatic mechanisms in biological neurons maintain fi ring activity between predefi ned ranges. Our model is designed to correct out of range neuron activity over a relatively long period of time (seconds or minutes). The system is implemented in a robot’s sensory neurons and is the only form of adaptability used in the central network. The robot was fi rst tested extensively with a mechanism implemented for obstacle avoidance and wall following behaviours. The robot was not only able to deal with sensor manufacture defects, but to adapt to changing environments (e.g. adapting to a narrow environment when it was originally in an open world). Emergence of non-implemented behaviours has also been observed. For example, during wall following behaviour, the robot seemed, at some point, bored. It changed the direction it was following the wall. Or we also noticed during obstacle avoidance an emerging exploratory behaviour. The model has also been tested on more complex behaviours such as skototaxis, an escape response, and phonotaxis. Again, especially with skototaxis, emergent behaviours appeared such as unpredictability on where and when the robot will be hiding. It appears that the adaptation is not only driven by the environment but by the behaviour of the robot too. It is by the complex feedback between these two things that non-implemented behaviours emerge. We showed that homeostasis can be used to improve sensory signal processing in robotics and we also found evidence that the phenomenon can be a necessary step towards better behavioural adaptation to the environment.
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3

Walish, Joseph John. "Bio-inspired optical components." Thesis, Massachusetts Institute of Technology, 2008. http://hdl.handle.net/1721.1/45950.

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Thesis (Ph. D.)--Massachusetts Institute of Technology, Dept. of Materials Science and Engineering, 2008.<br>Includes bibliographical references.<br>Guiding electro-magnetic radiation is fundamental to optics. Lenses, mirrors, and photonic crystals all accomplish this task by different routes. Understanding the interaction of light with materials is fundamental to improving and extending optical science and engineering as well as producing novel optical elements. Improvement in this understanding should not only include work to understand the interaction with traditional engineering materials but also should target the understanding of the interaction of electromagnetic radiation with biological structures as millions of years of evolution have sorted out numerous ways to modulate light (e.g. the fish eye or the skin of the octopus). The goal of this thesis work is to fabricate novel optical elements by taking cues from nature and extending the state of the art in light guiding behavior. Here, optical elements are defined as structured materials that guide or direct electromagnetic radiation in a predetermined manner. The work presented in this thesis encompasses biologically inspired tunable multilayer reflectors made from block copolymers and improvements to liquid filled lenses which mimic the human eye.In this thesis a poly(styrene)-poly(2-vinylpyridine) block copolymer was used to create a bio-mimetic, one-dimensional, multilayer reflector. The wavelengths of light reflected from this multilayer reflector or Bragg stack were tuned by the application of stimuli which included temperature, change in the solvent environment, pH, salt concentration in the solvent, and electrochemistry.<br>(cont.) A linear-shear rheometer was also built to investigate the mechanochromic color change brought about through the shearing of a one-dimensional, high molecular-weight, block-copolymer, photonic gel. Biologically inspired lenses were also studied through the construction of a finite element model which simulated the behavior of a liquid-filled lens. Several tunable parameters, such as the modulus, internal residual stress, and thickness of the membrane were studied for their influence on the shape of the lens membrane. Based on these findings, suggestions for the reduction of spherical aberration in a liquid filled lens were made. A gradient in the elastic modulus of the membrane was also investigated for use in the reduction of spherical aberration.<br>by Joseph John Walish.<br>Ph.D.
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Johnson, Benjamin C. F. (Benjamin Cedar Fruehauf). "Bio-inspired swimming helix." Thesis, Massachusetts Institute of Technology, 2012. http://hdl.handle.net/1721.1/77023.

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Thesis (M. Eng.)--Massachusetts Institute of Technology, Dept. of Electrical Engineering and Computer Science, 2012.<br>Cataloged from PDF version of thesis.<br>Includes bibliographical references (p. 59-60).<br>This thesis investigated a bio-inspired swimming chain (BISH), inspired by Weelia cylindrica. After developing a model, it was used to investigate conditions under which helical motion would emerge. The properties of this chain as the number of nodes changes was also investigated, to see if the helical motion or other properties of its motion were emergent behaviors. Other modes of motion were also observed. Optimization of the angle of propulsion of each was performed, and other optimizations attempted, although practical difficulties prevented useful results. A ten node chain was constructed to empirically verify the helical mode of motion.<br>by Benjamin C. F. Johnson.<br>M.Eng.
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5

Chan, Brian 1980. "Bio-inspired fluid locomotion." Thesis, Massachusetts Institute of Technology, 2009. http://hdl.handle.net/1721.1/49762.

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Thesis (Ph. D.)--Massachusetts Institute of Technology, Dept. of Mechanical Engineering, 2009.<br>Includes bibliographical references (leaves 95-99).<br>We have developed several novel methods of locomotion at low Reynolds number, for both Newtonian and non-Newtonian fluids: Robosnails 1 and 2, which operate on a lubrication layer, and the three-link swimmer which moves in an unbounded fluid. Robosnail 1 utilizes lubrication pressures generated in a Newtonian fluid under a steadily undulating foot to propel itself forward. Tractoring force and velocity measurements are in agreement with analytic and numerical solutions. Robosnail 2, modeled after real land snails, uses in-plane compressions of a flat foot on a mucus substitute such as Laponite or Carbopol. Robosnail 2 exploits the non-Newtonian qualities (yield-stress, shear thinning) of the fluid solution to locomote. The glue-like behavior of the unyielded fluid allows Robosnail 2 to climb up a 90 degree incline or inverted 180 degree surfaces. The three-link swimmer is a device composed of three rigid links interconnected by two out-of-phase oscillating joints. It is the first experimental test that successfully demonstrates that a swimmer of its kind can translate in the Stokes limit.<br>by Brian Chan.<br>Ph.D.
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6

Colas, Clémentine. "Bio-inspired synthetic crystals." Thesis, université Paris-Saclay, 2022. http://www.theses.fr/2022UPASF044.

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Les biominéraux calcaires présentent une grande variété de formes et de fonctions biologiques, mais également un certain nombre de traits structuraux communs. En particulier, ils apparaissent, dans leur grande majorité, comme formés d'un assemblage de nanoparticules cristallines sphéroïdales, tout en ayant des propriétés cristallines voisines de celles d'un monocristal. La compacité de cette nanostructure suggère l'existence d'un transitoire liquide précédant la formation d'un état amorphe, quant à lui démontré dans un certain nombre de cas. Le chemin de cristallisation, qui mettrait ainsi en jeu des états intermédiaires typiques des processus de cristallisation dits non-classiques, n'est pas entièrement établi à ce jour. En particulier, l'existence d'une phase liquide enrichie en ions reste complexe à démontrer in vivo. Afin d'évaluer la pertinence d'une telle hypothèse, une approche basée sur un modèle synthétique incluant une phase liquide dense a été utilisée. Des films de carbonate de calcium amorphes d'épaisseur sub-micronique ont été produits par diffusion de CO₂ gazeux dans une solution calcique en présence de polyelectrolyte anionique. Le mécanisme de formation des films, associant le développement d'un motif 2D par séparation de phase liquide-liquide et l'agrégation irréversible de nanoparticules amorphes formées en solution, a été démontré. Les films amorphes ont été cristallisés par chauffage, exposition à une humidité relative contrôlée, ou vieillissement dans le milieu réactionnel. La caractérisation de ces cristaux 2D, notamment par ptychographie de Bragg, a permis de décrire les mécanismes de transition amorphe-cristal et préciser les propriétés cristallines pour chaque condition de cristallisation. Certains cristaux présentent des propriétés très semblables aux cristaux biogéniques, appuyant ainsi l'hypothèse d'un intermédiaire liquide dans la biominéralisation calcaire<br>Calcareous biominerals present a great variety of forms and biological functions, but also a number of common structural features. In particular, they appear, in their great majority, to be formed by an assembly of spheroidal crystalline nanoparticles, while having crystalline properties close to those of a single crystal. The compactness of this nanostructure suggests the existence of a liquid transient prior to the formation of an amorphous state, which has been evidenced in a number of cases. The crystallisation pathway, which would involve intermediate states typical of so-called non-classical crystallisation processes, is not yet fully established. In particular, the existence of an ion-enriched liquid phase remains complex to demonstrate in vivo. In order to assess the relevance of such a hypothesis, an approach based on a synthetic model including a dense liquid phase was used. Amorphous calcium carbonate films of sub-micron thickness were produced by CO₂ gas diffusion in a calcium solution in the presence of anionic polyelectrolyte. The mechanism of film formation, combining the development of a 2D pattern by liquid-liquid phase separation and the irreversible aggregation of amorphous nanoparticles formed in solution, was demonstrated. The amorphous films were crystallized by heating, exposure to controlled relative humidity, or aging in the reaction medium. The characterization of these 2D crystals, in particular by Bragg ptychography, has made it possible to describe the amorphous-crystal transition mechanisms and to specify the crystalline properties for each crystallization condition. Some crystals show properties very similar to biogenic crystals, thus supporting the hypothesis of a liquid intermediate in calcareous biomineralization
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Pillai, Karthik. "Bio-inspired Cellulose Nanocomposites." Diss., Virginia Tech, 2011. http://hdl.handle.net/10919/28575.

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Natural composites like wood are scale-integrated structures that range from molecular to the macroscopic scale. Inspired by this design, layer-by-layer (LbL) deposition technique was used to create lignocellulosic composites from isolated wood polymers namely cellulose and lignin, with a lamellar architecture. In the first phase of the study, adsorption of alkali lignin onto cationic surfaces was investigated using a quartz crystal microbalance with dissipation monitoring (QCM-D). Complete coverage of the cationic surface with alkali lignin occured at low solution concentration; large affinity coefficients were calculated for this system at differing pH levels. Adsorption studies with organosolv lignin in an organic solvent, and spectroscopic analysis of mixtures of cationic polymer with alkali lignin revealed a non-covalent interaction. The work demonstrated how noncovalent interactions could be exploited to molecular organize thin polyphenolic biopolymers on cationic surfaces. The second phase of the study examined the adsorption steps during the LbL assembly process to create novel lignocellulosic composites. LbL assembly was carried out using oxidized nanocellulose (NC) and lignin, along with a cationic polymer poly(diallyldimethylammonium chloride) (PDDA). QCM-D was used to follow the sequential adsorption process of the three different polymers. Two viscoelastic models, namely Johannsmann and Voigt, were respectively used to calculate the areal mass and thickness of the adsorbed layers. Atomic force microscopy studies showed a complete coverage of the surface with lignin in all the disposition cycles, however, surface coverage with NC was seen to increase with the number of layers. Free-standing composite films were obtained when the LbL process was carried out for 250 deposition cycles (500 bilayers) on a cellulose acetate substrate, following the dissolution of the substrate in acetone. Scanning electron microscopy of the cryo-fractured cross-sections showed a lamellar structure, and the thickness per adsorption cycle was estimated to be 17 nm. The third phase of the study investigated the effect of LbL ordering of the polymers versus a cast film composed of a blended mixture of the polymers, using dynamic mechanical analysis. A tan ï ¤ peak was observed in the 30 â 40 ºC region for both films, which was observed in the neat NC film. Heating of the samples under a compressive force produced opposite effects in the films, as the LbL films exhibited swelling, whereas the cast films showed densification. The apparent activation energy of this transition (65 â 80 kJ mol-1) in cast films, calculated based on the Arrhenius equation was found to be coincident to those reported for the ï ¢ transition of amorphous cellulose. The peak was seen to disappear in case of LbL films in the second heat, whereas it was recurring in case of cast films of the blended mixture, and neat NC films. Altogether, the together the work details a novel path to integrate an organized lignin and cellulose molecular structure, albeit modified from their native form, into a three-dimensional composite material.<br>Ph. D.
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Varadarajan, Aravind Krishnan. "Improving Bio-Inspired Frameworks." Thesis, Virginia Tech, 2018. http://hdl.handle.net/10919/97506.

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In this thesis, we provide solutions to two different bio-inspired algorithms. The first is enhancing the performance of bio-inspired test generation for circuits described in RTL Verilog, specifically for branch coverage. We seek to improve upon an existing framework, BEACON, in terms of performance. BEACON is an Ant Colony Optimization (ACO) based test generation framework. Similar to other ACO frameworks, BEACON also has a good scope in improving performance using parallel computing. We try to exploit the available parallelism using both multi-core Central Processing Units (CPUs) and Graphics Processing Units(GPUs). Using our new multithreaded approach we can reduce test generation time by a factor of 25�-- compared to the original implementation for a wide variety of circuits. We also provide a 2-dimensional factoring method for BEACON to improve available parallelism to yield some additional speedup. The second bio-inspired algorithm we address is for Deep Neural Networks. With the increasing prevalence of Neural Nets in artificial intelligence and mission-critical applications such as self-driving cars, questions arise about its reliability and robustness. We have developed a test-generation based technique and metric to evaluate the robustness of a Neural Nets outputs based on its sensitivity to its inputs. This is done by generating inputs which the neural nets find difficult to classify but at the same time is relatively apparent to human perception. We measure the degree of difficulty for generating such inputs to calculate our metric.<br>MS
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9

Gordon, Christal. "Bio-inspired, bio-compatible, reconfigurable analog CMOS circuits." Diss., Georgia Institute of Technology, 2009. http://hdl.handle.net/1853/37222.

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This work details CMOS, bio-inspired, bio-compatible circuits which were used as synapses between an artificial neuron and a living neuron and between two living neurons. An intracellular signal from a living neuron was amplified, an integrate-and-fire neuron was used as a simple processing element to detect the spikes, and an artificial synapse was used to send outputs to another living neuron. The key structure is an electronic synapse which is based around a floating-gate pFET. The charge on the floating-gate is analogous to the synaptic weight and can be modified. This modification can be viewed as similar to long-term potentiation and long-term depression. The modification can either be programmed (supervised learning) or can adapt to the inputs (unsupervised learning). Since the technology to change the floating-gate weight has greatly improved, these weights can be set quickly and accurately. Intrinsic floating-gate learning rules were explored and the ability to change the synaptic weight was shown.
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McCarroll, Niall. "BioFace : bio-inspired face detection." Thesis, Ulster University, 2017. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.722684.

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The goal of face detection is to determine whether or not an image or video frame contains faces and, if present, return the number of instances of each face object and their location within an image space. Face detection is an important computer vision task as it is the building block for more sophisticated face processing algorithms such as face recognition and facial expression tracking. However, robust and reliable face detection in completely unconstrained settings remains a very challenging task. For example, while the human brain performs face detection and recognition robustly and with apparent ease, computer algorithms continue to find this a difficult task due to the huge variation of facial appearance in still images and video sequences. The existing literature documents extensive work on face detection utilising different classical machine learning and traditional algorithmic techniques. Given that challenges such as invariance to facial pose still remain with these traditional machine learning approaches, an exploration of biologically representative solutions that behave adaptively and autonomously through learning may help account for the well documented superior human and primate detection performance. In an effort to implement a more biologically plausible approach to invariant multi-view face detection, this thesis presents a novel hierarchical Spiking Neural Network (SNN) framework that adopts a hybrid approach to learning. This is achieved by combining a bottom-up unsupervised Spike-Timing Dependent Plasticity (STDP) feature extraction and filtering phase with a supervised feature selection process that provides feedback to the framework in an effort to select the most diagnostic neurons for accurate face detection. The detection accuracy of the hybrid system is further enhanced through two biologically plausible mechanisms of error control; namely threshold potential adaptation and spike latency thresholding. The broadly tuned behaviour of the neurons allows for a small but expressive set of multi­view neurons to achieve efficient and robust detection for multi-view face poses. The merged, multi-view face detection system is further adapted through a competitive lateral inhibition mechanism to achieve accurate in-plane and out-of-plane face pose estimation.
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Broecker, Bastian. "Bio-inspired multi-robot coordination." Thesis, University of Liverpool, 2018. http://livrepository.liverpool.ac.uk/3025355/.

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This works addresses the complexity of coordinating in large multi-robot systems (MRS), by drawing inspiration from simple and effective strategies, observable in social-insect colonies e.g. ants and bees. These insects have evolved over a long period of time and show remarkable behaviours that are highly suitable for addressing the complex tasks that they are facing. In this thesis we introduce two novel social-insect based approaches, providing simple and effective coordination in the field of multi-robot coverage and explore their performances and properties in extensive case studies. To address their limitations in real-world situations, we introduce and evaluate an end-to-end system to allow their deployment on light weight robotic systems.
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Woo, Sung Sik Ph D. Massachusetts Institute of Technology. "Bio-inspired collective analog computation." Thesis, Massachusetts Institute of Technology, 2012. http://hdl.handle.net/1721.1/78365.

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Thesis (S.M.)--Massachusetts Institute of Technology, Dept. of Electrical Engineering and Computer Science, 2012.<br>This electronic version was submitted by the student author. The certified thesis is available in the Institute Archives and Special Collections.<br>Cataloged from student-submitted PDF version of thesis.<br>Includes bibliographical references (p. 101-102).<br>In this thesis, I present electronic circuit systems that mimic collective analog com- putation found in biology. By combining the advantages of analog and digital computation, these systems can lead to highly complex, rapid, and energy-efficient systems such as an analog supercomputer that is capable of simulating a great number of bio- chemical reactions in cells. To this end, I first implement a neuron-inspired collective analog adder in a standard 0.5 [mu]m CMOS process. It serves as a prototype system that visualizes fundamental design ideas and techniques for building a collective analog computation system. Next, I build a cell-inspired analog circuit system which efficiently models bacterial genetic circuits in a cell, which can provide a powerful modeling and simulation tool for the design and analysis of circuits in synthetic and systems biology.<br>by Sung Sik Woo.<br>S.M.
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Ferraro, Claudio. "Bio-inspired ceramic based composites." Thesis, Imperial College London, 2016. http://hdl.handle.net/10044/1/45538.

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The progress of a wide range of strategic fields from aerospace, construction, transportation or medicine depends on the ability to develop new materials combining different structural and functional properties, from lightweight to high fracture resistance. One way of achieving this is by borrowing design principles found in Natural materials such as bone or nacre and integrating them into man-made materials. A common characteristic of these Natural composites is the combination of hard and soft phases in hierarchical structures with characteristic dimensions spanning multiple length scales. The process of adapting natural structural features to new technologies is called “bio-inspiration”. This PhD project, attempts to mimic some of the structural motifs found in natural materials to produce innovative lightweight ceramic structures and ceramic-based composites with high fracture resistance. Freeze casting (also known as ice-templating) was used to produce strong and lightweight SiC scaffolds using SiC particles with two different morphologies: spherical nanoparticles (400 nm in diameter) and micro-fibres (~18 μm long and ~1.5 μm in diameter). In both cases the optimal rheological behaviour for the freeze casting slurries along with optimal sintering conditions for the consolidation of the freeze cast scaffolds have been identified. Freeze casting of nanoparticle suspensions resulted in porous layered scaffolds with wavelengths (lamella wall plus pore space) ranging from ~60 to ~15 microns and porosity between ~50% and ~75%. The packing of fibres during freeze casting allowed the formation of highly porous networks with porosities as high as 98%. The mechanical (compressive and flexural strength) and functional properties (electrical conductivity, thermal conductivity) of the scaffolds have been measured and related to their structure. These scaffolds have been employed as preforms to produce SiC based composites through infiltration of the residual porosity with two different polymers: PMMA and Epoxy resin. The distinctive layered architecture of the composites enables a combination of high flexural strength and fracture resistance. The main toughening mechanisms (crack deflection, crack bridging, plastic deformation etc.) have been identified. To form metal-ceramic composites, layered freeze cast alumina preforms have been infiltrated with an aluminium alloy (Al-4Mg). The wettability of this alloy on alumina allows the infiltration of porous scaffolds without the application of external pressure. Therefore an extremely porous preform can be fully infiltrated without damaging the ceramic network. The microstructures of alumina preforms obtained from nanoparticles (400nm in diameter) or platelets (5-10μm in diameter and 300-500nm in thickness) have been compared. The use of platelets enables the fabrication of layered ceramic scaffolds with wall thickness of ~5-6μm. Mechanical tests revealed that the layered freeze casted composites exhibit a combination of high fracture resistance and flexural strength, with values that are superior to other metal-ceramic composites. Materials fabricated using alumina platelets can reach the strengths up to ~890MPa. All the materials exhibit stable crack propagation with a characteristic R-curve. An extensive study of crack interaction with the microstructural features has been performed to identify the key toughening mechanisms such as crack deflection, crack bridging, micro-cracking and plastic deformation. The results of this thesis suggest that the structure of natural materials can be used as a blueprint in the development of new advanced composites. This requires processing techniques able to implement, in practical dimensions, the design concepts found in natural materials. However, a deep understanding of the relationships between structure and mechanical response encompassing the influence of structural parameters acting at multiple length scales is still needed to guide this effort.
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Papadakis, Michail. "Bio-inspired production of dihydrogen." Electronic Thesis or Diss., Aix-Marseille, 2023. http://www.theses.fr/2023AIXM0061.

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Dans ce travail, nous avons synthétisé, caractérisé et testé différentes séries de complexes de nickel basés sur des ligands thiocarbazone pour leur capacité à produire de l’hydrogène à partir de deux processus catalytiques différents. La première partie de ce travail de thèse décrit l'utilisation de deux nouvelles familles basées sur des ligands bis-thiosemicarbazone et étudie comment une modulation appropriée du ligand peut affecter les performances électrocatalytiques pour la production d’hydrogène. La deuxième partie décrit l'utilisation d'un complexe de nickel polynucléaire et comment l'incorporation de plusieurs centres métalliques peut affecter l'activité électrocatalitique du système. Dans la dernière partie du manuscrit, de nouveaux systèmes photocatalytiques ont été développés en utilisant des nanoparticules de carbone comme capteurs de lumière et la série de complexes nickel à ligands thiosemicarbazones comme centres catalytiques pour photoproduire de l’hydrogène<br>In this work, we have synthesized, characterized and tested different series of nickel complexes based on thiocarbazone ligands for their ability to produce hydrogen from two different catalytic processes. The first part of this Ph.D. work describes the use of two new families based on bis-thiosemicarbazone ligands and investigates how appropriate ligand-tailoring can affect electrocatalytic performance for HER. The second part describes the use of a polynuclear nickel complex and how the incorporation of several metallic centers can affect electrocatalysis. In the last part of the manuscript, new photocatalytic systems were developed using carbon nanodots as light harvesters and the series of nickel-thiosemicarbazone complexes as catalytic centers for photo-producing hydrogen
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Torre, Anthony. "Bio-inspired waveforms and processing." Electronic Thesis or Diss., Ecole nationale supérieure Mines-Télécom Atlantique Bretagne Pays de la Loire, 2024. http://www.theses.fr/2024IMTA0448.

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Cette thèse aborde le sujet de la diversité des formes d’onde afin d’apporter des réponses aux problématiques radar actuelles, telles que la congestion croissante du spectre électromagnétique ou encore le besoin constant de performances améliorées (ou du moins maintenues). En étudiant le principe d’écholocation utilisé par les chauves-souris et leurs formes d’onde, les potentiels atouts de ces signaux innés sont mis en exergue. Une forme d’onde bio-inspirée, la forme d’onde de Parsons, capable d’imiter la construction des signaux de chauves-souris avec une certaine flexibilité, a ainsi été proposée pour des applications radar. Tout au long de la thèse, la comparaison est faite entre la fonction de Parsons et des formes d’ondes radar classiques (le chirp et la fonction hyperbolique) afin de mesurer le potentiel de cette forme d’onde bio-inspirée. En outre, ses réponses au traitement radar classique sont étudiées. En particulier, les bornes de Cramér-Rao ont été calculées pour quantifier l’efficacité de la forme d’onde dans l’estimation du délai et du Doppler. Des discussions sur des données simulées et réelles ont permis de valider la fonction de Parsons en tant que potentielle nouvelle forme d’onde radar. Pour aller plus loin, son implémentation dans des applications radar concrètes est étudiée. Enfin, à la suite de l’étude initiale sur les signaux de chauves-souris, un algorithme de détection de changement, le CuSum, est adapté et développé pour la détection de signaux radar inconnus<br>This thesis addresses the issue of waveform diversity to answer current challenges in radar, such as the increasing spectral congestion or the need for improved (or at least maintained) capabilities. By studying the echolocation of bats and their waveforms, the potential assets of such innate waveforms have been highlighted. A bio-inspired waveform, the Parsons waveform, which is capable of mimicking the design of bat waveforms with a notable flexibility, has thus been proposed for use in radar applications. All along this thesis, the comparison is made between the Parsons function and classical radar waveforms (the chirp and the hyperbolic frequency modulation) in order to assess the potential of the bio-inspired waveform. In addition, its responses to traditional radar processing have been studied. In particular, the Cramér-Rao lower bounds have been calculated to quantify the efficiency of the waveform in estimating delay and Doppler. Discussions on both simulated and real data have enabled the validation of the Parsons bio-inspired function as a potential new radar waveform. To further investigate this, its implementation in concrete radar applications is studied. Finally, following an initial study of bat signals, a change-point detection algorithm, namely the CuSum, is derived and developed for the detection of unknown radar signals
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Zolotovsky, Katia. "BioConstructs : methods for bio-inspired and bio-fabricated design." Thesis, Massachusetts Institute of Technology, 2012. http://hdl.handle.net/1721.1/77780.

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Thesis (S.M.)--Massachusetts Institute of Technology, Dept. of Architecture, 2012.<br>Cataloged from PDF version of thesis. Page 74 blank.<br>Includes bibliographical references (p. 72-73).<br>This work presents experimentation with design and fabrication methods, using biological systems either indirectly (as a source of inspiration and information for design) or directly (as a material production for fabrication). The focus is on "bioconstructs"- design methods and processes that are invented and developed under the influence of biological systems. Two projects are presented. The Polypterus project examines the unique design principles of the armor of an ancient fish and possible ways to use these principles in the design of synthetic protective and flexible applications (bio-inspired design). The project deals with the correlation between geometrical data (units' shape and rules of their composition on a surface) and functional data (anisotropic flexibility of the surface) to formulate a parametric design system. The Xylinus project focuses on the adaptation of material production by bacteria to a fabrication process (biofabrication). This fabrication method combines digital tools and technologies with material production by a living biological system. The long-term objective is to use cellulose-producing bacteria to develop an additive manufacturing technique for architecture and product design. Both projects suggest methods to utilize biological systems for innovative design and fabrication methods.<br>by Katia Zolotovsky.<br>S.M.
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Svagan, Anna. "Bio-inspired polysaccharide nanocomposites and foams." Licentiate thesis, KTH, Fibre and Polymer Technology, 2007. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-4260.

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<p>Today, the majority of materials used for single-use packaging are petroleum-based synthetic polymers. With increased concern about the environmental protection, efforts have been made to develop alternative biodegradable materials from renewable resources. Starch offers an attractive alternative since it is of low cost and abundant. However, the starch material is brittle without plasticizer and the mechanical properties of starch materials are highly sensitive to moisture.</p><p>In nature, the plant cell walls combine mechanical stiffness, strength and toughness despite a highly hydrated state. This interesting combination of properties is attributed to a network based on cellulose microfibrils. Inspired by this, microfibrillated cellulose (MFC) reinforced starch-based nanocomposites films and foams were prepared. Films with a viscous matrix and MFC contents from 10 to 70wt% were successfully obtained by solvent casting. The films were characterized by DSC, DMA, FE-SEM, XRD, mercury density measurements, and dynamic water vapor sorption (DVS). At 70wt% MFC content a high tensile strength together with high modulus and high work of fracture was observed. This was due to the nanofiber and matrix properties, favourable nanofiber-matrix interaction, a good dispersion of nanofibers and the MFC network.</p><p>Novel nanocomposite foams were obtained by freeze-drying aquagels prepared from 8wt% solutions of amylopectin starch and MFC. The MFC content was varied from 10 to 70wt%. For composite foam with MFC contents up to 40wt%, improved mechanical properties were observed in compression. The mechanical properties depended both on the cell wall properties and the cell-structure of the foam. The effect of moisture (20-80% RH) on the dynamical properties of composite foam with 40wt% MFC was also investigated and compared to those of neat starch foam. Improved storage modulus was noted with MFC content, which was a result of the nanofiber network in the cell-wall. In addition, the moisture content decreased with MFC content, due to the less hydrophilic nature of MFC.</p>
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Berg, Jannik, and Camilla Haukenes Karud. "Swarm intelligence in bio-inspired robotics." Thesis, Norges teknisk-naturvitenskapelige universitet, Institutt for datateknikk og informasjonsvitenskap, 2011. http://urn.kb.se/resolve?urn=urn:nbn:no:ntnu:diva-13684.

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In this report, we have explored swarm intelligence through a box-pushing taskwith physical robots called e-pucks. Research on social insects has been presentedtogether with dierent ways of controlling autonomous robots, where combiningthis knowledge has been essential in our quest to make a biological plausible antretrieving system.Inspired by ants and behavior-based robotics, we have created the system CRABS.It is based on Brooks&apos; subsumption architecture to control six dierent behaviors,from a xed input-output scheme. The system is designed to easily handle addingor removal of behavior layers. Behavior modules can also be used separately andported to other software or hardware platforms.During this project we came across several hardware and software challenges in-vestigating cooperative behavior. With the use of the simulation tool Webots, wewere able to determine e-pucks&apos; capabilities, and through this knowledge able todesign and construct an articial food source. This operated as the box-item in thebox-pushing task.Based on two types of sensors and two actuators (wheels), we had a strategy toaccomplish the box-pushing task following the biological principles of social insects.The guidelines of the ant retrieving model made CRABS a self-organized systemthat given three or more e-pucks, will always succeed in retrieving the box back tothe wall. The most remarkable view on this accomplishment is that is done throughthe use of only stigmergy and positive/negative feedback.One of the things we&apos;ve experienced throughout this thesis is that hardware is a morework demanding and inconsistent platform than your usual software simulation.Everything is not given, and although Webots provided helpful shortcuts, a lot oftime and hard work was put down in order to get the system up and running. Withthat being said, we are pleased that we took the hardware rout and were able totest and validate our system on physical robots.
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Javadi, Ailar. "Bio-inspired noise robust auditory features." Thesis, Georgia Institute of Technology, 2012. http://hdl.handle.net/1853/44801.

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The purpose of this work is to investigate a series of biologically inspired modifications to state-of-the-art Mel- frequency cepstral coefficients (MFCCs) that may improve automatic speech recognition results. We have provided recommendations to improve speech recognition results de- pending on signal-to-noise ratio levels of input signals. This work has been motivated by noise-robust auditory features (NRAF). In the feature extraction technique, after a signal is filtered using bandpass filters, a spatial derivative step is used to sharpen the results, followed by an envelope detector (recti- fication and smoothing) and down-sampling for each filter bank before being compressed. DCT is then applied to the results of all filter banks to produce features. The Hidden- Markov Model Toolkit (HTK) is used as the recognition back-end to perform speech recognition given the features we have extracted. In this work, we investigate the role of filter types, window size, spatial derivative, rectification types, smoothing, down- sampling and compression and compared the final results to state-of-the-art Mel-frequency cepstral coefficients (MFCC). A series of conclusions and insights are provided for each step of the process. The goal of this work has not been to outperform MFCCs; however, we have shown that by changing the compression type from log compression to 0.07 root compression we are able to outperform MFCCs for all noisy conditions.
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Svagan, Anna. "Bio-inspired polysaccharide nanocomposites and foams /." Stockholm : Kungliga Tekniska högskolan, 2006. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-4260.

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21

Burciu, Irina [Verfasser]. "Efficient bio-inspired sensing / Irina Burciu." Lübeck : Zentrale Hochschulbibliothek Lübeck, 2018. http://d-nb.info/1167559843/34.

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22

Ramezan, Shirazi Ataollah. "Bio-inspired self-organizing swarm robotics." Thesis, University of Surrey, 2017. http://epubs.surrey.ac.uk/844948/.

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Swarm robotics is the collaboration of a large number of robots to accomplish a set of specified tasks. It has great potential for the generation of self-organizing adaptive systems, where simple behaviours at agent level result in complex behaviours at swarm level. These systems promise to be robust, flexible, and scalable, and have many innovative applications in the future. Elimination of a central controller and instead relying on local awareness and distributed decision making are the main distinguishing characteristics of such, systems which make them different from classical engineering and necessitate a different design methodology. The challenges to design a control mechanism for self-organizing swarm robotic systems mainly come from the difficulty of mapping between the macroscopic behaviours of a swarm and the microscopic behaviours of its individual agents, and also decision making based on local awareness. Nature presents the best examples of self-organising collective systems. They can be divided into two categories, animal collective behaviours, and cellular organs. Although studying animal collective behaviours paves the way for understanding the principles of self-organizing collective systems, cellular organs show more complex behaviours and structures. The goal of this research is to adapt cellular morphogenesis mechanisms for collective behaviours in a swarm of minimalist robots. The trade of between the size of a swarm and the complexity of involved robots necessitates using simpler and cheaper robots. In addition, miniaturization of robots for future micro-robotic applications require to minimize the number of on-board devices in robots. In this thesis, we focus on developing minimalist algorithms inspired by biological morphogenesis for collective swarm behaviours, including collective flocking, target following, and target enclosure. The proposed algorithms are applicable to highly restricted robots without global positioning, directional sensing, motion feedback, and long-range communication devices. At first, I show how morphogens can retain the integrity and original shape of a swarm of robots without directional sensing, while the swarm moves and interacts with the environment. Then, a coordinated motion strategy is presented in order to preserve connectivity of a real swarm of minimalist robots following a target in their environment. Finally, a new approach is presented for target enclosure with a control over the shape of aggregation around the target. In this approach, a morphogen gradient produced by a target reacts with a second one diffusing through the edge of aggregation in order to spot weak points of the aggregation. The last two algorithms implemented in a real swarm of Kilobots.
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Starkey, Timothy Andrew. "Towards bio-inspired photonic vapour sensors." Thesis, University of Exeter, 2014. http://hdl.handle.net/10871/15827.

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Many highly-evolved bio-photonic structures, which tailor the propagation of light by coherent optical scattering, have been investigated. These natural designs, which have many diverse ecological functions, are becoming increasingly studied as sources of innovation and inspiration for a range of scientific, technological, and commercial applications. The brilliant blue colour reflected from the scales of the Morpho butterfly is just one example of nature’s ability to manipulate light and colour strongly. In this thesis, the photonic structure present in the scales of the Morpho butterfly is investigated as a source of bio-inspiration in the pursuit of high- performance photonic vapour sensors. The intention of this is to outperform classical sensor approaches which traditionally suffer from poor selectivity between chemical species. By measuring the change in reflectance from the iridescent scales of the Morpho butterfly, both a sensitive and, critically, a selective response to chemical vapours can be obtained. Here, the origin of this unique multivariable vapour-induced optical response is investigated, and this biological template is further explored as a source of innovation for the mature field of chemical sensing. By using synergy between experimental and theoretical techniques, a mechanism for the sensitive and selective response of the Morpho butterfly’s scales to different chemical vapour environments is elucidated. This mechanism arises from combined chemical and physical effects within the photonic nanostructure. Following this, demonstrations of this biological template’s vapour response attributes, which have large and desirable diversity in the optical responses, are made. These response attributes are visualised in the spectral changes associated with optical excitation conditions, such as from different angles and polarisation states, and also in the temporal response profiles. Finally, theoretical sensor designs that outperform the Morpho scales are described. Simple principles that might improve the currently unacceptable levels of selectivity in contemporary sensor implementations are outlined and the vapour response of a Morpho-inspired photonic structure is presented.
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Pinto, Preston Albert. "Novel Bio-inspired Aquatic Flow Sensors." Thesis, Virginia Tech, 2012. http://hdl.handle.net/10919/33807.

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Inspired by the roles of hair cells in nature, this study aims to develop and characterize two new sets of novel flow sensors. One set of sensors developed and studied in this work are flow sensors fabricated using carbon nanomaterials. These sensors are made by embedding carbon nanotubes (CNT) and carbon nanohorns (CNH) into a polymeric substrate and then tested by flowing a conductive aqueous solution over the surface of the exposed CNT and CNH. In response, a flow-dependent voltage is generated. The surface coverage and the electrical relationship between the sensor and water is investigated and the voltage measurements of sensors with different levels of resistance were tested in varying fluid velocities. In response to these fluid velocities, the least resistive sensor showed small, but detectable changes in voltages, while higher resistance sensors showed less response. In addition, plasma treatment of the carbon nanomaterial/PDMS films were conducted in order to render the PDMS on the surface hydrophilic and in turn to pull more fluid towards the carbon material. This showed to improve the sensitivity of the flow sensors. This work also builds on previous research by investigating the flow dependent electrical response of a â skinâ -encapsulated artificial hair cell in an aqueous flow. An artificial cell membrane is housed in a flexible polyurethane substrate and serves as the transduction element for the artificial hair cell. Flow experiments are conducted by placing the bio-inspired sensor in a flow chamber and subjecting it to pulse-like flows. This study demonstrates that the encapsulated artificial hair cell flow sensor is capable of sensing changes in flow through a mechanoelectrical response and that its sensing capabilities may be altered by varying its surface morphology. Furthermore, the sensorâ s response and dynamics as a function of its surface morphology and structural properties are investigated through synchronized motion tracking of the hair with a laser vibrometer and current measurements across the artificial cell membrane.<br>Master of Science
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YAN, XUESONG. "RUBBER REINFORCEMENT WITH BIO-INSPIRED ANALOGUES." University of Akron / OhioLINK, 2018. http://rave.ohiolink.edu/etdc/view?acc_num=akron1543416438259149.

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Guo, Hua. "Bio-inspired surface engineering for hydrophobicity." Thesis, Edith Cowan University, Research Online, Perth, Western Australia, 2014. https://ro.ecu.edu.au/theses/1013.

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Highly evolved, efficient and sophisticated biological systems can be used as models for scientific innovations. This research explored specific surface structures on plant leaves with respect to their hydrophobicity in the context of the often arid Australian climate. The relationships between leaf surface structures and their hydrophobicity could inform the making of artificial surfaces with specially designed hydrophobicity. Moderate hydrophobicity and strong surface adhesion were discovered on many study plant leaves. Scanning Electron Microscopy (SEM) revealed that their surface morphologies could be categorized into four groups while their water-repellent mechanisms were considered at an individual species level. Specifically, physical models were built based on the topography of several Eucalyptus species. Wetting robustness and surface free energy analyses were performed with these models to study wetting transitions on surfaces with specific microscopic features. In the fabrication component of the study, a convenient self-assembly procedure of oxysilane successfully converted a hydrophilic glass slide into a hydrophobic surface, with the measured contact angle changing from 30.8 to more than 1000. Atomic force microscope (AFM) images showed randomly distributed roughness at a micrometre scale on these self-assembled hydrophobic surfaces. Samples with square arrays of micro-posts were also fabricated following a sophisticated photo-lithography process. Wetting properties similar to some leaves, namely moderate hydrophobicity and strong surface adhesion, were observed with these fabricated samples. Anisotropic wetting, liquid-surface contact footprints and base lengths on these micro-textured surfaces were also investigated. Finally, fluorine containing diamond-like carbon (F-DLC) coatings were examined because of their chemical inertness, mechanical durability, and low surface energy. F-DLC films were prepared by closed-field, unbalanced, magnetron sputtering (CFUBMS) on silicon substrate to study their wetting and mechanical properties. The influences of CF4 and C2H2 gas addition during fabrication on these properties were explored by measuring contact angles, fluorine contents, surface roughness, Young's modulus and hardness. Simulation from Finite Element Analysis with COMSOL software was also conducted to confirm the mechanical results obtained in nano-indentation experiments. The leaf surface geometries revealed in this study could trigger further relevant research and applications. Surface free energy analysis on the built models could lead to a deeper theoretical understanding of wetting state transition for these geometries. The preliminary results on the self-assembly of oxysilane at ambient conditions could contribute to the development of cost-efficient and environmentally friendly methods for fabricating durable hydrophobic coatings. The results of F-DLC coatings could be beneificial for manipulating surface free energy and mechanical properties, to match specific requirements for certain applications.
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Müller, Sibylle D. "Bio-inspired optimization algorithms for engineering applications /." Zürich, 2002. http://e-collection.ethbib.ethz.ch/show?type=diss&nr=14719.

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Luke, Stephen. "Towards bio-inspired broadband optical scattering systems." Thesis, University of Exeter, 2011. http://hdl.handle.net/10036/3212.

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This thesis presents a study of the mechanisms by which white coloured appearances are created in biological samples. The primary aim of this work is the identification and characterisation of white insect species species, namely, achieving a fundamental understanding of the designs by which the highly efficient broadband scatter is cre- ated. The subsequent aim of this work concerns the use of these design principles in bio–inspired applications for technological gain. Previously observed structures are de- scribed, relevant electromagnetic theory is summarised, a range of key sample species is investigated and bio–inspired broadband scatter principles are used to fabricate pro- totype paper products. A wide range of white butterflies was investigated with electron microscopy. Pieris rapae, the small cabbage white, was chosen for detailed characterisation. An array of ellipsoidal pterin beads enhances optical scatter from its wing scales. The colour quality of its wing appearance could be controlled by chemical extraction of the pterin beads. Detailed optical modelling revealed the contribution to optical scatter of the wing–scale superstructure. The disordered structure within the scales of the beetle Cyphochilus is compared with that of two further beetle species, Lepidiota stigma and Calothyrza margaritifera. The bright white colouration of each species is attributed to high efficiency, wavelength– independent optical scatter from irregular microstructures within their scales. Finite element method and Mie theory modelling, along with experimental data, indicate varying degrees of optimisation of the three species’ microstructures. Cyphochilus ex- hibits the structure with the highest degree of optimisation; its scale filling fraction, scattering centre size and spacing are shown to be highly optimised. The final section of this thesis is devoted to the application of bio–inspired designs to the paper industry. Enhanced optical performance, through the optimisation of the mineral particle coating layers which are used to improve the optics of paper products, through mimicry of these butterfly and beetle structures is the goal of this section of the work. Knowledge gained through the investigation of the biological samples was applied to a range of paper samples with experimental coating layers.
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Zuniga, Virgilio. "Bio-inspired optimization algorithms for smart antennas." Thesis, University of Edinburgh, 2011. http://hdl.handle.net/1842/5766.

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This thesis studies the effectiveness of bio-inspired optimization algorithms in controlling adaptive antenna arrays. Smart antennas are able to automatically extract the desired signal from interferer signals and external noise. The angular pattern depends on the number of antenna elements, their geometrical arrangement, and their relative amplitude and phases. In the present work different antenna geometries are tested and compared when their array weights are optimized by different techniques. First, the Genetic Algorithm and Particle Swarm Optimization algorithms are used to find the best set of phases between antenna elements to obtain a desired antenna pattern. This pattern must meet several restraints, for example: Maximizing the power of the main lobe at a desired direction while keeping nulls towards interferers. A series of experiments show that the PSO achieves better and more consistent radiation patterns than the GA in terms of the total area of the antenna pattern. A second set of experiments use the Signal-to-Interference-plus-Noise-Ratio as the fitness function of optimization algorithms to find the array weights that configure a rectangular array. The results suggest an advantage in performance by reducing the number of iterations taken by the PSO, thus lowering the computational cost. During the development of this thesis, it was found that the initial states and particular parameters of the optimization algorithms affected their overall outcome. The third part of this work deals with the meta-optimization of these parameters to achieve the best results independently from particular initial parameters. Four algorithms were studied: Genetic Algorithm, Particle Swarm Optimization, Simulated Annealing and Hill Climb. It was found that the meta-optimization algorithms Local Unimodal Sampling and Pattern Search performed better to set the initial parameters and obtain the best performance of the bio-inspired methods studied.
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Deng, Yinhu. "Bio-inspired Multifunctional Coatings and Composite Interphases." Doctoral thesis, Saechsische Landesbibliothek- Staats- und Universitaetsbibliothek Dresden, 2016. http://nbn-resolving.de/urn:nbn:de:bsz:14-qucosa-212223.

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Graphene nanoplatelets have been introduced into the interphase between electrically insulating glass fibre and polymer matrix to functionalize the traditional composite. Owing to the distribution of network structure of GNPs, the interphase can transfer the signals about various internal change of material. Consequently, due to the novel bio-inspired overlapping structure, our GNPs-glass fibre shows a unique opportunity as a micro-scale multifunctional sensor. The following conclusions can be drawn from present research: • We prepared GNPs solution via a scalable and highly effective liquid-phase exfoliation method. This method produces high-quality, unoxidized graphene flakes from flake graphite. We control the thickness and size of GNPs by varying the centrifugation rate. • A simple fibre oriented capillary flow which can suppress ‘coffee ring’ effect to deposit GNPs onto the curved glass fibre surface. The GNPs form continuous fish scales like overlapping structure. • The electrical conductivity of our GNPs-glass fibre shows semiconductive property. The electrical resistance value scattering and the advancing contact angle value scattering indicate a uniform deposit structure. The uniform overlapping structure is a key factor for higher electrical conductivity compared with our previous work with CNTs. • The contact angles of our GNPs-glass fibre with water indicate that the GNPs are almost unoxidized, so the inert GNPs coating decreases the interfacial shears strength. • A micro scale GNPs-glass fibre sensor for gas sensing is achieved by deposit GNPs onto glass fibre surface. This sensor can be used to detect solvents vapours, such as water, ethanol and acetone. All these vapours work as electron acceptor when reacting with GNPs. The acetone shows the highest sensitivity (45000%) compared with water and ethanol. • The doping-dedoping of GNPs-glass fibres during adsorption-desorption cycles of acetone result in the efficient “break-junction” (GNPs lost electron carrier concentration) mechanism, which provides the possibility to fabricate the electrochemical “switch” in a simple and unique way. • The resistance of our GNPs-glass fibre shows exponential relationship with RH. This is attributed to two points. Firstly, the water vapours show similar exponential adsorption on carbon surface; secondly, the bandgap of GNPs increases with the increase of adsorbed water vapour concentration. • Due to the weak van der Waals interaction when water molecules are adsorbed on GNPs surface, our GNPs-glass fibre shows extreme fast response and recovery time with RH. It is potential for our GNPs-glass fibre being used to monitor the breath frequency. • Utilizing the negative temperature coefficient of GNPs, our GNPs-glass fibre can be used as temperature sensor with a sensing region of -150 to 30 °C. • Through the observed abnormal resistance change at a temperature of about – 18 °C, we discovered a phase change of the trance confined water in graphene layers. Based on the resistance change, we can study the interaction of water and carbon nanoparticles. • The bio-inspired novel overlapped multilayer structure of GNPs coating shows structural colours. Even more, our GNPs-glass fibre can be used to monitor the loading force in the interphase when it is embedded into epoxy resin. • Our GNPs-glass fibre shows an excellent piezoresistive property, the single GNPs-glass fibre shows a larger gauge factor than the commercial strains sensor. • The semiconductive interphase was formed when the GNPs-glass fibre was embedded in polymer matrix. This semiconductive interphase is very sensitive to the deformation of material, therefore, an in-situ strain sensor was manufactured to real-time monitor the microcracks in a composite instead of external sensors. The area of resistance ‘jump’ increase can be seen as the feature area for damage’s early warning. • Monitoring the resistance variation of the single fibre composite was conducted under cyclic loading with progressively increasing the strain peaks in order to further investigate the response of in-situ sensor to the interphase damage process. The deviation of resistance/strain when the stress is larger than 2 % highlights the accumulation of damage, which gives insight into the mechanism of resistance change.
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Iliadi, Konstantina. "Bio-inspired voice recognition for speaker identification." Thesis, University of Southampton, 2016. https://eprints.soton.ac.uk/413949/.

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Speaker identification (SID) aims to identify the underlying speaker(s) given a speech utterance. In a speaker identification system, the first component is the front-end or feature extractor. Feature extraction transforms the raw speech signal into a compact but effective representation that is more stable and discriminative than the original signal. Since the front-end is the first component in the chain, the quality of the later components is strongly determined by its quality. Existing approaches have used several feature extraction methods that have been adopted directly from the speech recognition task. However, the nature of these two tasks is contradictory given that speaker variability is one of the major error sources in speech recognition whereas in speaker recognition, it is the information that we wish to extract. In this thesis, the possible benefits of adapting a biologically-inspired model of human auditory processing as part of the front-end of a SID system are examined. This auditory model named Auditory Image Model (AIM) generates the stabilized auditory image (SAI). Features are extracted by the SAI through breaking it into boxes of different scales. Vector quantization (VQ) is used to create the speaker database with the speakers’ reference templates that will be used for pattern matching with the features of the target speakers that need to be identified. Also, these features are compared to the Mel-frequency cepstral coefficients (MFCCs), which is the most evident example of a feature set that is extensively used in speaker recognition but originally developed for speech recognition purposes. Additionally, another important parameter in SID systems is the dimensionality of the features. This study addresses this issue by specifying the most speaker-specific features and trying to further improve the system configuration for obtaining a representation of the auditory features with lower dimensionality. Furthermore, after evaluating the system performance in quiet conditions, another primary topic of speaker recognition is investigated. SID systems can perform well under matched training and test conditions but their performance degrades significantly because of the mismatch caused by background noise in real-world environments. Achieving robustness to SID systems becomes an important research problem. In the second experimental part of this thesis, the developed version of the system is assessed for speaker data sets of different size. Clean speech is used for the training phase while speech in the presence of babble noise is used for speaker testing. The results suggest that the extracted auditory feature vectors lead to much better performance, i.e. higher SID accuracy, compared to the MFCC-based recognition system especially for low SNRs. Lastly, the system performance is inspected with regard to parameters related to the training and test speech data such as the duration of the spoken material. From these experiments, the system is found to produce satisfying identification scores for relatively short training and test speech segments.
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Balme, Sebastien, Jean-Marc Janot, Philippe Dejardin, et al. "Ionic diffusion through a bio-inspired membrane." Diffusion fundamentals 16 (2011) 31, S. 1-2, 2011. https://ul.qucosa.de/id/qucosa%3A13764.

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33

Cambier, Nicolas. "Bio-inspired collective exploration and cultural organisation." Thesis, Compiègne, 2019. http://www.theses.fr/2019COMP2511.

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Les systèmes autonomes sont récemment devenus une solution efficace pour des applications telles que l'exploration et la surveillance d'environnements. Dans ces situations, l'utilisation de plusieurs robots pourrait améliorer l'efficacité des solutions proposées, bien que cela nécessite des stratégies d'organisation qui soient à la fois robuste, flexible et adaptables à la taille de la flotte de robots. En robotique en essaim, ces qualités sont assurées par la décentralisation, la redondance (plusieurs/tous les robots effectuent la même tâche), des interactions locales et des règles simples. Les interactions et communications locales sont une composante clef de la robotique en essaim. Jusqu'ici, la communication n'a été utilisée que pour des tâches relativement simples, tels que signaler les préférences ou l'état d'un robot. Cependant, la communication peut être bien plus riche et similaire aux langages humains. Dans ces conditions, elle permettrait aux essaims de robots de gérer de nouvelles situations qui ne seraient pas prévues par leurs concepteurs. De riches communications sont donc nécessaires pour obtenir des essaims entièrement autonomes, en particulier dans des environnements inconnus. Dans cette thèse, nous proposons une approche pour faire émerger des communications riches dans des essaims de robots en utilisant les jeux de langages comme protocole de communication et l'agrégation probabiliste comme cas d'étude. L'agrégation probabiliste est un prérequis pour de nombreuses tâches en robotique en essaim mais elle est aussi extrêmement sensible aux conditions expérimentales. Elle requiert donc un réglage spécifique de ses paramètres pour chaque nouvelle condition, y compris les changements d'échelle ou de densité. Avec notre approche, nous avons observé que l'exécution simultanée du jeu de nommage et de l'agrégation mène, dans certaines conditions, à un nouveau comportement d'agglomération en plusieurs groupes, chacun avec son propre nom, qui est contrôlable via les paramètres de l'agrégation. En poussant ces interactions plus loin, nous démontrons que les dynamiques sociales du jeu de nommage peuvent sélectionner des paramètres d'agrégation efficaces. Cette sélection culturelle crée donc des contrôleurs résilients, qui évoluent en-ligne en fonction du contexte courant<br>Automatically-controlled artificial systems have recently been used in numerous settings including environmental monitoring and explorations, with great success. In such cases, the use of multiple robots could increase efficiency, although we should ensure that their communication and organisation strategies are robust, exible, and scalable. These qualities can be ensured through decentralisation, redundancy (many/all robots perform the same task), local interaction, and simplistic rules, as is the case in swarm robotics. One of the key components of swarm robotics is local interaction or communication. The later has, so far, only been used for relatively simple tasks such as signalling a robot's preference or state. However, communication has more potential because the emergence of meaning, as it exists in human language, could allow robots swarms to tackle novel situations in ways that may not be a priori obvious to the experimenter. This is a necessary feature for having swarms that are fully autonomous, especially in unknown environments. In this thesis, we propose a framework for the emergence of meaningful communications in swarm robotics using language games as a communication protocol and probabilistic aggregation as a case study. Probabilistic aggregation can be a prerequisite to many other swarm behaviours but, unfortunately, it is extremely sensitive to experimental conditions, and thus requires specific parameter tuning for any setting such as population size or density.With our framework, we show that the concurrent execution of the naming game and of probabilistic aggregation leads, in certain conditions, to a new clustering and labelling behaviour that is controllable via the parameters of the aggregation controller. Pushing this interplay forward, we demonstrate that the social dynamics of the naming game can select efficient aggregation parameters through environmental pressure. This creates resilient controllers as the aggregation behaviour is dynamically evolved online according to the current environmental setting
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34

Kea, Kara Dominique. "Bio-Inspired Segmented Self-Centering Rocking Frame." Thesis, Virginia Tech, 2015. http://hdl.handle.net/10919/54000.

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This paper investigates the development, design and modeling of a human spine-inspired seismic lateral force resisting system. The overall goal is to create a design for a lateral force resisting system that reflects human spine behavior that is both practical and effective. The first phase of this project involved a literature review of the human spine and rocking structural systems. The goal of this phase was to identify concepts from the spine that could be transferred to a lateral force resisting system. The second phase involved creating a 3-dimensional model of the lumbar region of the spine in SAP2000 and using it to examine concepts that could be transferred to a lateral force resisting system. The third phase consisted of creating possible system designs using concepts and principles identified through phases one and two and identifying a final system design. The last phase involved modeling the final lateral force resisting system design in SAP2000, validating the model and testing the design's effectiveness. This paper shows that this system is a viable option to prevent permanent structural damage in buildings during a seismic event.<br>Master of Science
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35

Shanmuganathan, Kadhiravan. "Bio-inspired Stimuli-responsive Mechanically Dynamic Nanocomposites." Case Western Reserve University School of Graduate Studies / OhioLINK, 2010. http://rave.ohiolink.edu/etdc/view?acc_num=case1276792579.

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36

Constandinou, Timothy. "Bio-inspired electronics for micropower vision processing." Thesis, Imperial College London, 2007. http://hdl.handle.net/10044/1/1290.

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Vision processing is a topic traditionally associated with neurobiology; known to encode, process and interpret visual data most effectively. For example, the human retina; an exquisite sheet of neurobiological wetware, is amongst the most powerful and efficient vision processors known to mankind. With improving integrated technologies, this has generated considerable research interest in the microelectronics community in a quest to develop effective, efficient and robust vision processing hardware with real-time capability. This thesis describes the design of a novel biologically-inspired hybrid analogue/digital vision chip ORASIS1 for centroiding, sizing and counting of enclosed objects. This chip is the first two-dimensional silicon retina capable of centroiding and sizing multiple objects2 in true parallel fashion. Based on a novel distributed architecture, this system achieves ultra-fast and ultra-low power operation in comparison to conventional techniques. Although specifically applied to centroid detection, the generalised architecture in fact presents a new biologically-inspired processing paradigm entitled: distributed asynchronous mixed-signal logic processing. This is applicable to vision and sensory processing applications in general that require processing of large numbers of parallel inputs, normally presenting a computational bottleneck. Apart from the distributed architecture, the specific centroiding algorithm and vision chip other original contributions include: an ultra-low power tunable edge-detection circuit, an adjustable threshold local/global smoothing network and an ON/OFF-adaptive spiking photoreceptor circuit. Finally, a concise yet comprehensive overview of photodiode design methodology is provided for standard CMOS technologies. This aims to form a basic reference from an engineering perspective, bridging together theory with measured results. Furthermore, an approximate photodiode expression is presented, aiming to provide vision chip designers with a basic tool for pre-fabrication calculations.
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37

Tsai, Shang-Feng (Frank). "Bio-inspired fluidic lens for biomedical applications." Diss., [La Jolla] : University of California, San Diego, 2010. http://wwwlib.umi.com/cr/ucsd/fullcit?p3389690.

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Thesis (Ph. D.)--University of California, San Diego, 2010.<br>Title from first page of PDF file (viewed February 17, 2010). Available via ProQuest Digital Dissertations. Vita. Includes bibliographical references.
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38

Balme, Sebastien, Jean-Marc Janot, Philippe Dejardin, et al. "Ionic diffusion through a bio-inspired membrane." Universitätsbibliothek Leipzig, 2015. http://nbn-resolving.de/urn:nbn:de:bsz:15-qucosa-184872.

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39

Wright, Mark. "Delivery of CO by bio-inspired metallocentres." Thesis, University of East Anglia, 2016. https://ueaeprints.uea.ac.uk/63544/.

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Although once thought to have no beneficial medicinal value due to its historic reputation as being a ‘silent killer’, recent investigations into the therapeutic applications of carbon monoxide (CO) on mammalian physiology have sparked a growing interest in designing metal-based carbonyl complexes to act as pro-drugs. Thoughtful design of transition metal carbonyl complexes result in controllable and tunable CO release triggered by photochemical labilization from the metal centre. The work contained in this thesis focuses on the design, synthesis and CO release capabilities of a series of photoactive ironbased carbon monoxide releasing molecules (photoCORMs). This work is complimented with studies of analogous ruthenium complexes. PhotoCORMs are able to impart spatial and temporal control over CO delivery following site specific irradiation with an appropriate wavelength. High energy ultra-violet light has poor tissue penetration and causes damage to the skin. Here, a series of iron carbonyl complexes were synthesised. Extension of the ligand conjugation system and addition of a nitrogen donor group proved to shift the absorption spectrum in a bathochromic fashion. Examination of photoCORM capabilities reveal the iron carbonyl complexes release CO following visible light irradiation. The number of developed CORMs which satisfy the required pharmaceutical characteristics is relatively small. Essential characteristics include water solubility and biocompatibility. We expand on the design of our complexes by incorporating thiolated saccharide ligands into the coordination sphere. The resulting dimeric carbonyl complexes display significantly enhanced water solubility as well as a major change in CO release behaviour. The anti-inflammatory properties of the photoCORM systems were investigated in vitro. Production of LPS-induced pro-inflammatory cytokine, TNF-a was markedly decreased following CORM administration. Surprisingly, CORM potency was greatest when cells were kept in the dark. Designing two photon up-converter systems is a leading strategy to enhanced the light harvesting ability of metal complexes. Here, the design of such attachable systems is discussed.
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40

GOBBATO, THOMAS. "Bio-inspired Nano-Architectures for Artificial Photosynthesis." Doctoral thesis, Università degli Studi di Trieste, 2023. https://hdl.handle.net/11368/3041030.

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Among the possible technologies for artificial photosynthesis, photoelectrochemical cells possess the advantage to decouple the overall water splitting reaction into the related semi-reactions enabling the study and optimization of the single process. In this Thesis a novel approach towards artificial photosystems design has been reported. The quantasome approach is a unique bio-inspired design strategy that pair down to essentials the PSII mimicry by shaping an innovative supramolecular material with the essential components of the quantasome: a light-harvesting antenna and a catalytic reaction center embedded in a unique ensemble. Bonchio, Prato and co-workers reported the very first example of an artificial quantasome (QS), a supramolecular artificial photosystem designed for light-induced water oxidation reaction. This innovative material is composed of a bis-cationic perylene bisimide photosensitizer (PBI2+) and a deca-anionic state-of-the-art water oxidation catalyst (Ru4POM). The artificial quantasome assembly forms in water, exploiting the complementary electrostatic interactions and hydrophobic-hydrophilic properties of the two selected molecular building blocks resulting in a supramolecular material (QS) with a definite chromophore to catalyst stoichiometry of 5:1. The structural characterization of this artificial quantasome (QS) and its building blocks, using state-of-the-art techniques of scanning probe microscopy and electron microscopy, is reported. The experiments performed point out to a lamellar structure of the supramolecular material resembling the self-organization of the natural enzyme PSII. This project aimed also at the synthesis of new artificial photosystems, indeed innovative hydrophilic photosynthetic materials are obtained by a combined supramolecular and click-chemistry strategy. The designed synthetic procedure adopted relies on click-chemistry functionalization of the N-terminal positions of PBI scaffolds. The functionalization of the N-terminal positions of a PBI scaffold set the parallelism with the natural antennae, that via N-terminal loops interactions modulate the structure of PSII-LHCII supercomplexes. Both new chromophores PBIn-TEGlock and PBI-TEGunlock present and estimated potential of the excited state suitable to drive photo-assisted water oxidation. Moreover, the synthetic route here reported is envisaged to maintain the positive peripherical charges on the molecular structures obtained in order to exploit complementary electrostatic interaction with Ru4POM water oxidation catalyst (WOC). The interactions of these new antennae with Ru4POM WOC yield unprecedented artificial quantasomes (QS-TEGlock, QS-TEGunlock) with tetraethylene glycol (TEG) functionalization. Photoelectrocatalytic characterization of the new artificial quantasomes is reported by coupling the supramolecular materials with state-of-the-art “inverse opal” indium tin oxide (IO-ITO) substrates. IO architectures are selected because their structure is reported to promote internal light scattering, due to the intrinsic geometry of the 3D-photoconductive lattice. QS-TEGlock exhibits a superior response for all the conditions explored, reporting a 340% photocurrent enhancement with respect to QS. In order to decouple the hydrophilic effect of TEG terminals from their cross-linking impact photoelectrocatalytic characterization of QS-TEGunlock is achieved. It is found that the decoration of the PBI chromophores with TEG residues, with or without cross-linking, can leverage the quantasome hydration and facilitate water oxidation reaction. Formation of TEG-templated hydration shells is verified by Raman microscopy of water exposed photoanodes.11 The presence of TEG-templated hydration shells sets a parallelism with natural PSII water channels. The added value of TEG cross-linkers is probed under prolonged photoelectrolysis whereby the unlocked structure reports a major photocurrent loss with respect to the locked one.<br>Among the possible technologies for artificial photosynthesis, photoelectrochemical cells possess the advantage to decouple the overall water splitting reaction into the related semi-reactions enabling the study and optimization of the single process. In this Thesis a novel approach towards artificial photosystems design has been reported. The quantasome approach is a unique bio-inspired design strategy that pair down to essentials the PSII mimicry by shaping an innovative supramolecular material with the essential components of the quantasome: a light-harvesting antenna and a catalytic reaction center embedded in a unique ensemble. Bonchio, Prato and co-workers reported the very first example of an artificial quantasome (QS), a supramolecular artificial photosystem designed for light-induced water oxidation reaction. This innovative material is composed of a bis-cationic perylene bisimide photosensitizer (PBI2+) and a deca-anionic state-of-the-art water oxidation catalyst (Ru4POM). The artificial quantasome assembly forms in water, exploiting the complementary electrostatic interactions and hydrophobic-hydrophilic properties of the two selected molecular building blocks resulting in a supramolecular material (QS) with a definite chromophore to catalyst stoichiometry of 5:1. The structural characterization of this artificial quantasome (QS) and its building blocks, using state-of-the-art techniques of scanning probe microscopy and electron microscopy, is reported. The experiments performed point out to a lamellar structure of the supramolecular material resembling the self-organization of the natural enzyme PSII. This project aimed also at the synthesis of new artificial photosystems, indeed innovative hydrophilic photosynthetic materials are obtained by a combined supramolecular and click-chemistry strategy. The designed synthetic procedure adopted relies on click-chemistry functionalization of the N-terminal positions of PBI scaffolds. The functionalization of the N-terminal positions of a PBI scaffold set the parallelism with the natural antennae, that via N-terminal loops interactions modulate the structure of PSII-LHCII supercomplexes. Both new chromophores PBIn-TEGlock and PBI-TEGunlock present and estimated potential of the excited state suitable to drive photo-assisted water oxidation. Moreover, the synthetic route here reported is envisaged to maintain the positive peripherical charges on the molecular structures obtained in order to exploit complementary electrostatic interaction with Ru4POM water oxidation catalyst (WOC). The interactions of these new antennae with Ru4POM WOC yield unprecedented artificial quantasomes (QS-TEGlock, QS-TEGunlock) with tetraethylene glycol (TEG) functionalization. Photoelectrocatalytic characterization of the new artificial quantasomes is reported by coupling the supramolecular materials with state-of-the-art “inverse opal” indium tin oxide (IO-ITO) substrates. IO architectures are selected because their structure is reported to promote internal light scattering, due to the intrinsic geometry of the 3D-photoconductive lattice. QS-TEGlock exhibits a superior response for all the conditions explored, reporting a 340% photocurrent enhancement with respect to QS. In order to decouple the hydrophilic effect of TEG terminals from their cross-linking impact photoelectrocatalytic characterization of QS-TEGunlock is achieved. It is found that the decoration of the PBI chromophores with TEG residues, with or without cross-linking, can leverage the quantasome hydration and facilitate water oxidation reaction. Formation of TEG-templated hydration shells is verified by Raman microscopy of water exposed photoanodes.11 The presence of TEG-templated hydration shells sets a parallelism with natural PSII water channels. The added value of TEG cross-linkers is probed under prolonged photoelectrolysis whereby the unlocked structure reports a major photocurrent loss with respect to the locked one.
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41

Santi, Sofia. "Bio-inspired materials for spinal cord regeneration." Doctoral thesis, Università degli studi di Trento, 2021. http://hdl.handle.net/11572/319486.

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This work proposes minimally invasive solutions for spinal cord regeneration after trauma. In particular, injectable biomaterials can be precisely positioned in the lesion site, and eventually repetitively injected until the complete regeneration of the tissue. For this application, a silk fibroin functionalized with collagen type IV and laminin-derived peptides, called bio-inspired multifunctionalized silk fibroin (BMS), possessing piezoelectric properties, has been synthesized. Another approach that avoids damages to the spinal cord is proposed in the thesis as a multilayer hydrogel with piezoelectric properties that acts as a bridge between the healthy parts surrounding the injury. The multilayer hydrogel consists of i) a thin-layer of gelatin and fish collagen functionalized with VEGF for blood vessels formation, which helps the survival of the cells integrating with the pia mater of the spinal cord; ii) a BMS layer, which helps the adhesion, migration of neural stem cells and induces the sprouting of the axons thanks to the presence of Netrin (a chemoattractive protein); and iii) an adhesive layer of polydopamine (PDA) to fix the patch on the injured site. The adhesive patch exhibits a potential larger than an injectable hydrogel that could guarantee a long-term cell survival and help the axons to move towards a direction. The adhesive patch will be located on the surface of the spinal cord and the chemoattractive protein will induce the sprouting of the ascendant or descendant axons in the spinal cord to reach the axons present in the patch, restoring a signal connection. Even if not final, the results indicate that the above strategy could be explored further for the regeneration of the spinal cord.
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42

Santi, Sofia. "Bio-inspired materials for spinal cord regeneration." Doctoral thesis, Università degli studi di Trento, 2021. http://hdl.handle.net/11572/319486.

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This work proposes minimally invasive solutions for spinal cord regeneration after trauma. In particular, injectable biomaterials can be precisely positioned in the lesion site, and eventually repetitively injected until the complete regeneration of the tissue. For this application, a silk fibroin functionalized with collagen type IV and laminin-derived peptides, called bio-inspired multifunctionalized silk fibroin (BMS), possessing piezoelectric properties, has been synthesized. Another approach that avoids damages to the spinal cord is proposed in the thesis as a multilayer hydrogel with piezoelectric properties that acts as a bridge between the healthy parts surrounding the injury. The multilayer hydrogel consists of i) a thin-layer of gelatin and fish collagen functionalized with VEGF for blood vessels formation, which helps the survival of the cells integrating with the pia mater of the spinal cord; ii) a BMS layer, which helps the adhesion, migration of neural stem cells and induces the sprouting of the axons thanks to the presence of Netrin (a chemoattractive protein); and iii) an adhesive layer of polydopamine (PDA) to fix the patch on the injured site. The adhesive patch exhibits a potential larger than an injectable hydrogel that could guarantee a long-term cell survival and help the axons to move towards a direction. The adhesive patch will be located on the surface of the spinal cord and the chemoattractive protein will induce the sprouting of the ascendant or descendant axons in the spinal cord to reach the axons present in the patch, restoring a signal connection. Even if not final, the results indicate that the above strategy could be explored further for the regeneration of the spinal cord.
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43

Dourgaparsad, Kevin. "Superhydrophobic bio-inspired microarchitectured stainless steel surfaces." Electronic Thesis or Diss., Université de Lille (2022-....), 2024. https://pepite-depot.univ-lille.fr/ToutIDP/EDSMRE/2024/2024ULILR009.pdf.

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Les surfaces superhydrophobes ont une faible mouillabilité à l'eau du fait de leur nature chimique et/ou de leur état de surface architecturé à plusieurs échelles (micro et nano). Les procédés de fabrication additive (FA) utilisant de l'acier inoxydable sont coûteux en raison du prix de la poudre d'acier inoxydable. De plus, la précision de ces technologies descend rarement en dessous de 200 μm. Les travaux présentés couplent deux technologies, à savoir l'impression 3D polymère et la coulée sous vide (fonderie à cire perdue) pour créer, à partir de déchets d'acier inoxydable, diverses surfaces bio-inspirées microtexturées en acier inoxydable 316L. Le moulage des détails micrométriques en fonderie d'acier inoxydable est un défi technique en raison de la tension superficielle élevée, de la viscosité dynamique élevée et de la température de travail élevée (1600°C). Diverses surfaces microtexturées bioinspirées (écailles de poisson, gouttes, nid d'abeille, etc.) ont été fabriquées avec succès. Un revêtement à l'échelle nanométrique a ensuite été appliqué par polymérisation plasma à pression atmosphérique afin de nanotexturer la surface, conduisant la surface à un comportement ultrahydrophobe. Enfin, diverses applications possibles pour ces surfaces, comme l'anti-fouling, l'anti-icing ou l'imprégnation d'huile végétale pour la mise au point de surface glissantes (SLIPS) sont explorées et discutées<br>Superhydrophobic surfaces have low water wetting due to their chemical nature and/or surface state structured at multiple scales (micro and nano). Additive manufacturing (AM) processes using stainless steel are expensive due to the cost of stainless steel powder. Additionally, the precision of these technologies rarely goes below 200 μm. The presented work combines two technologies, namely polymer 3D printing and vacuum casting (lost-wax casting), to create various bio-inspired microtextured surfaces in 316L stainless steel from stainless steel waste. Casting micrometric details in stainless steel foundry is a technical challenge due to high surface tension, high dynamic viscosity, and high working temperature (1600°C). Various bioinspired microtextured surfaces (fish scales, drops, honeycomb, etc.) have been successfully manufactured. A nanoscale coating was then applied through atmospheric pressure plasma polymerization to nanotexture the surface, leading to an ultrahydrophobic behavior. Finally, various potential applications for these surfaces, such as anti-fouling, anti-icing, or impregnation with vegetable oil for the development of slippery liquid-infused porous surfaces (SLIPS), are explored and discussed
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44

Castro, Junior Olacir Rodrigues. "Bio-inspired optimization algorithms for multi-objective problems." reponame:Repositório Institucional da UFPR, 2017. http://hdl.handle.net/1884/46312.

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Orientador : Aurora Trinidad Ramirez Pozo<br>Coorientador : Roberto Santana Hermida<br>Tese (doutorado) - Universidade Federal do Paraná, Setor de Ciências Exatas, Programa de Pós-Graduação em Informática. Defesa: Curitiba, 06/03/2017<br>Inclui referências : f. 161-72<br>Área de concentração : Computer Science<br>Resumo: Problemas multi-objetivo (MOPs) são caracterizados por terem duas ou mais funções objetivo a serem otimizadas simultaneamente. Nestes problemas, a meta é encontrar um conjunto de soluções não-dominadas geralmente chamado conjunto ótimo de Pareto cuja imagem no espaço de objetivos é chamada frente de Pareto. MOPs que apresentam mais de três funções objetivo a serem otimizadas são conhecidos como problemas com muitos objetivos (MaOPs) e vários estudos indicam que a capacidade de busca de algoritmos baseados em Pareto é severamente deteriorada nesses problemas. O desenvolvimento de otimizadores bio-inspirados para enfrentar MOPs e MaOPs é uma área que vem ganhando atenção na comunidade, no entanto, existem muitas oportunidades para inovar. O algoritmo de enxames de partículas multi-objetivo (MOPSO) é um dos algoritmos bio-inspirados adequados para ser modificado e melhorado, principalmente devido à sua simplicidade, flexibilidade e bons resultados. Para melhorar a capacidade de busca de MOPSOs, seguimos duas linhas de pesquisa diferentes: A primeira foca em métodos de líder e arquivamento. Trabalhos anteriores apontaram que esses componentes podem influenciar no desempenho do algoritmo, porém a seleção desses componentes pode ser dependente do problema. Uma alternativa para selecioná-los dinamicamente é empregando hiper-heurísticas. Ao combinar hiper-heurísticas e MOPSO, desenvolvemos um novo framework chamado H-MOPSO. A segunda linha de pesquisa também é baseada em trabalhos anteriores do grupo que focam em múltiplos enxames. Isso é feito selecionando como base o framework multi-enxame iterado (I-Multi), cujo procedimento de busca pode ser dividido em busca de diversidade e busca com múltiplos enxames, e a última usa agrupamento para dividir um enxame em vários sub-enxames. Para melhorar o desempenho do I-Multi, exploramos duas possibilidades: a primeira foi investigar o efeito de diferentes características do mecanismo de agrupamento do I-Multi. A segunda foi investigar alternativas para melhorar a convergência de cada sub-enxame, como hibridizá-lo com um algoritmo de estimativa de distribuição (EDA). Este trabalho com EDA aumentou nosso interesse nesta abordagem, portanto seguimos outra linha de pesquisa, investigando alternativas para criar versões multi-objetivo de um dos EDAs mais poderosos da literatura, chamado estratégia de evolução baseada na adaptação da matriz de covariância (CMA-ES). Para validar o nosso trabalho, vários estudos empíricos foram conduzidos para investigar a capacidade de busca das abordagens propostas. Em todos os estudos, nossos algoritmos investigados alcançaram resultados competitivos ou melhores do que algoritmos bem estabelecidos da literatura. Palavras-chave: multi-objetivo, algoritmo de estimativa de distribuição, otimização por enxame de partículas, multiplos enxames, híper-heuristicas.<br>Abstract: Multi-Objective Problems (MOPs) are characterized by having two or more objective functions to be simultaneously optimized. In these problems, the goal is to find a set of non-dominated solutions usually called Pareto optimal set whose image in the objective space is called Pareto front. MOPs presenting more than three objective functions to be optimized are known as Many-Objective Problems (MaOPs) and several studies indicate that the search ability of Pareto-based algorithms is severely deteriorated in such problems. The development of bio-inspired optimizers to tackle MOPs and MaOPs is a field that has been gaining attention in the community, however there are many opportunities to innovate. Multi-objective Particle Swarm Optimization (MOPSO) is one of the bio-inspired algorithms suitable to be modified and improved, mostly due to its simplicity, flexibility and good results. To enhance the search ability of MOPSOs, we followed two different research lines: The first focus on leader and archiving methods. Previous works have pointed that these components can influence the algorithm performance, however the selection of these components can be problem-dependent. An alternative to dynamically select them is by employing hyper-heuristics. By combining hyper-heuristics and MOPSO, we developed a new framework called H-MOPSO. The second research line, is also based on previous works of the group that focus on multi-swarm. This is done by selecting as base framework the iterated multi swarm (I-Multi) algorithm, whose search procedure can be divided into diversity and multi-swarm searches, and the latter employs clustering to split a swarm into several sub-swarms. In order to improve the performance of I-Multi, we explored two possibilities: the first was to further investigate the effect of different characteristics of the clustering mechanism of I-Multi. The second was to investigate alternatives to improve the convergence of each sub-swarm, like hybridizing it to an Estimation of Distribution Algorithm (EDA). This work on EDA increased our interest in this approach, hence we followed another research line by investigating alternatives to create multi-objective versions of one of the most powerful EDAs from the literature, the Covariance Matrix Adaptation Evolution Strategy (CMA-ES). In order to validate our work, several empirical studies were conducted to investigate the search ability of the approaches proposed. In all studies, our investigated algorithms have reached competitive or better results than well established algorithms from the literature. Keywords: multi-objective, estimation of distribution algorithms, particle swarm optimization, multi-swarm, hyper-heuristics.
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45

João, Dias Ferreira. "Bio-Inspired Self-Organisation in Evolvable Production Systems." Licentiate thesis, KTH, Produktionssystem, 2013. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-129481.

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The increasing market fluctuations and customized products demand have dramatically changed the focus of industry towards organizational sustainability and supply chain agility. Such critical changes in the strategic vision of the companies inevitably have a direct impact on the shop-floor operational requirements. In this sense, traditional shop-floor approaches are becoming increasingly inadequate leading to the adoption of more pluggable and reusable solutions. The emergence o modern manufacturing paradigms translates the effort undertaken by the academia in order to provide the required background to support the implementation of such distributed mechatronic systems. Biological systems, due to their similar distributed network-like structure, represent naturally a common analogy and source of inspiration for such distributed modular approaches. Hence, modern manufacturing paradigms usually rely on complexity science biologically inspired concepts to attain distributed control, adaptability, evolution, flexibility and robustness as core concepts. This originated the implementation of a number of different multi-agent based architectures. Nevertheless, with time the majority of the these implementation efforts left behind most of the bio-inspired concepts resulting in simple distributed approaches with considerable limitations regarding scalability, reconfigurability and distributed problem resolution. Particularly under the scope of Evolvable Production System (EPS) the implementation of self-organising mechanisms based on negotiation interaction protocols and dynamic coalition-based hierarchical complexity, have considerable hindered the system performance and limited the full exploitation of the paradigm potential. In this context, this licentiate thesis is focused on the development of a self-organising manufacturing systems that holistically mimics the main structural and regulatory principles followed by natural systems. For this purpose, the present approach was designed as opposed to the current tendency followed by modern productions approaches, in which the product holds the production knowledge and is responsible for the management of its own production. Instead, the production knowledge was reduced to the minimum and distributed over the manufacturing components. Self-organising principles heavily inspired on the regulatory mechanisms of biological systems, were then devised to regulate the critical control mechanisms of the manufacturing system. Hence, similarly to the natural world the characteristics and the system overall production emerge as consequence of the micro-dynamics of the systems. In this way, it becomes therefore possible to attain a system that is not only highly reconfigurable and scalable but also able to distributively tackle the manufacturing processes. Although the present work has been developed under the Evolvable Production System context, the introduced approach can be easily adapted to a wider range of modular networked-based systems.<br><p>QC 20131001</p>
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46

Wu, Wencen. "Bio-inspired cooperative exploration of noisy scalar fields." Diss., Georgia Institute of Technology, 2013. http://hdl.handle.net/1853/48940.

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A fundamental problem in mobile robotics is the exploration of unknown fields that might be inaccessible or hostile to humans. Exploration missions of great importance include geological survey, disaster prediction and recovery, and search and rescue. For missions in relatively large regions, mobile sensor networks (MSN) are ideal candidates. The basic idea of MSN is that mobile robots form a sensor network that collects information, meanwhile, the behaviors of the mobile robots adapt to changes in the environment. To design feasible motion patterns and control of MSN, we draw inspiration from biology, where animal groups demonstrate amazingly complex but adaptive collective behaviors to changing environments. The main contributions of this thesis include platform independent mathematical models for the coupled motion-sensing dynamics of MSN and biologically-inspired provably convergent cooperative control and filtering algorithms for MSN exploring unknown scalar fields in both 2D and 3D spaces. We introduce a novel model of behaviors of mobile agents that leads to fundamental theoretical results for evaluating the feasibility and difficulty of exploring a field using MSN. Under this framework, we propose and implement source seeking algorithms using MSN inspired by behaviors of fish schools. To balance the cost and performance in exploration tasks, a switching strategy, which allows the mobile sensing agents to switch between individual and cooperative exploration, is developed. Compared to fixed strategies, the switching strategy brings in more flexibility in engineering design. To reveal the geometry of 3D spaces, we propose a control and sensing co-design for MSN to detect and track a line of curvature on a desired level surface.
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47

Copley, Graeme. "Synthesis and Characterisation of Bio-inspired Molecular Dyads." Thesis, University of Newcastle Upon Tyne, 2009. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.515093.

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48

Etoundi, Appolinaire C. "Development studies of a bio-inspired condylar joint." Thesis, University of Bristol, 2013. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.619141.

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Limitations on space and power mean that limb joints for robots and prosthetics must be highly optimised for mechanical performance in areas such as stiffness, strength, friction , mechanical advantage, backlash and endurance. Biological joints me remarkably compact and long lasting and therefore it is desirable to produce bio-inspired of joints. This thesis presents a bio-inspired joint for robotics and prosthetics which is based on the human knee joint. The novel condylar joint has the same desirable features as the human knee joint including compactness is, high mechanical advantage: high stiffness and locking in the upright position. The condylar hinge joint has a mechanical advantage that is greater than that for a pin-jointed hinge by up to 35% which means that the actuator force can be reduced by up to 35% for squatting type movements. A design process has been developed for designing a condylar hinge joint for different applications. This is non-trivial because for each four-bar mechanism geometry and femur profile theme is a unique profile of tibia that has to be determined. ,ln addition, if there are constraints on the size of the tibia then it is necessary to have an iterative design process. A |Matlab code has been developed to generate the tibia profile from an animation of the four-bar motion. Parametric performance maps have been developed for two particular femur profiles. These maps show how performance varies for different four-bar mechanism geometrics. Four measures of performance are modelled which are peak mechanical advantage, RMS mechanical advantage, slicing ratio and angular range. Over 12,000 design cases have been modelled and these arc presented on a total of 44 design maps. A full size prototype has been built and tested for stiffness, friction and endurance. Additional rapid prototyping tests have been conducted in order to assess the feasibility of rapid joint construction for prosthetics.
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49

Olof, Sam Nicholas. "Chemical and optical manipulation of bio-inspired architectures." Thesis, University of Bristol, 2013. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.633110.

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50

Ortega-Sanchez, Cesar A. "Embryonics : a bio-inspired fault-tolerant multicellular system." Thesis, University of York, 2000. http://etheses.whiterose.ac.uk/2495/.

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