Rigidity of spherical codes

A packing of spherical caps on the surface of a sphere (that is, a spherical code) is called rigid or jammed if it is isolated within the space of packings. In other words, aside from applying a global isometry, the packing cannot be deformed. In this paper, we systematically study the rigidity of spherical codes, particularly kissing configurations. One surprise is that the kissing configuration of the Coxeter-Todd lattice is not jammed, despite being locally jammed (each individual cap is held in place if its neighbors are fixed); in this respect, the Coxeter-Todd lattice is analogous to the face-centered cubic lattice in three dimensions. By contrast, we find that many other packings have jammed kissing configurations, including the Barnes-Wall lattice and all of the best kissing configurations known in four through twelve dimensions. Jamming seems to become much less common for large kissing configurations in higher dimensions, and in particular it fails for the best kissing configurations known in 25 through 31 dimensions. Motivated by this phenomenon, we find new kissing configurations in these dimensions, which improve on the records set in 1982 by the laminated lattices.Comment: 39 pages, 8 figure

Effects of reinforcements on the preservation of paintings on work panel

To evaluate reinforcement design, this thesis combines observations on panel paintings, interviews with panel specialists, conservation records, and deformation analyses of constructed mock-ups of thinned panels bearing a selection of reinforcements. Reinforcements were reviewed, classified, and damaging effects discussed, with particular emphasis on the role of attitudes toward flattening of panel paintings. Mock-up surface deformations were then recorded during controlled changes in relative humidity (RH) using digital photogrammetry, moiré fringe analysis, and raking-light photography. Results for unreinforced panels emphasised that wood movement causes deformations, not just in the transverse- grain direction, but in three dimensions, which must interact with reinforcement. A consistent pattern of overall panel warp was shown which decreases in rate and amplitude with increasing panel thickness, including considerable warp parallel to the grain, heretofore ignored. Important results for reinforced mock-ups showed that during changes in RH, in-plane restraint by reinforcements such as laminates or battens fixed to the panel back causes bending in the opposite sense to that in which warp would occur in an unreinforced panel. For relatively rigid and sliding reinforcements, in-plane movement in the transverse-grain direction at the panel surface appears to be increased by restraining warp in a flat plane. Use of more flexible reinforcements should reduce associated stresses. For cradled panels, a pattern of strain exists on the coated side which corresponds with cradle structure. Combining this information with recorded out-of-plane deformations and examples of panel paintings with cradled- related damages, "washboarding" and related deterioration were explained in more detail than before. Reported twists or concave deformations soon after lamination with balsa and wax-resin adhesive/mortar are attributed to contraction during cooling and solidification of molten wax-resin. Design improvements are suggested such as encouraging use of more flexible reinforcements. Marking their first application to art conservation and in particular to analysis of panel painting deformations, digital photogrammetry and moiré fringe analysis were shown to be very suitable techniques

Development of microcantilever biosensing platforms

Microcantilever sensor system as a promising field attracted much attention recently. This system has the potential to be applied for a biosensing technology which is parallel reference, label free, sensitive and real time. In this thesis, polyimide has been selected as a material to fabricate cantilever due to its excellent physical, electrical and mechanical properties, on top of its cost advantage. Importantly, we showed it is feasible to microfabricate large array of microcantilever sensors with high-power UV laser directly. It is low cost and rapid, the parameters for laser direct writing fabrication has been studied. The thesis also shows that it is possible to functionalise the polyimide film first and subsequently cut it to functionalised cantilever sensor array. The unique fabrication and functionalisation process can solve the problem of high-cost microfabrication using silicon and low-efficient functionalisation using capillary tubing all together. In addition, the fabrication process has been further developed to avoid the problem of the cross contamination from receptors on both sides. With this improvement, we developed an internally referenced microcantilever biosensors system for DNA hybridization detection. Different receptors can be coated on each side of the polymer film before fabricating to cantilever biosensors This newly developed capability enables us to coat receptors with similar but slightly different biological properties on each side of the cantilever sensor, a process which is extremely difficult by using conventional capillary tubing methods due to the possibility of thiol exchange on surfaces and hence cross-contamination. A polyimide microcantilever sensor with embedded microfluidic channel has been developed in this thesis. Photoresist material is used to form the precise microfluidic channel within the microcantilever device. The multilayer polymer film device is still soft enough to operate in static mode. The main advantage of the system presented here is that since the device is made entirely of polymer materials, the fabrication process is simple and low-cost. The magnetic beads have been used to amplify the signal of the biosensing processing; the application of polyimide microfluidic microcantilevers to the detection of Cryptosporidium and thrombin is reported in this thesis. Paper based autonomous micocantilever system has also been investigated in this thesis. We build a cantilever system without external pump or force with paper and magnetic field. The limitation of the system is that it takes too much time to pump magnetic beads through the cantilever with capillary. However, we found that it has the potential to develop a long time range timer based on the slowest property. Different methods have been investigated to slow down the speed, when liquid pass through the paper microfluidic. Finally, we demonstrate some timer devices whose ranges are from minutes to month. The devices have the potential to be used as time-based diagnostic assays, food label, etc

Generative design for agile robot based additive manufacturing for sustainable aesthetic furniture products

This thesis was submitted for the degree of Doctor of Philosophy and awarded by Brunel University LondonThe Furniture manufacturing industry has been slow to adopt the latest manufacturing technologies, relying heavily upon specialised conventional machinery. This approach not only requires high levels of specialist knowledge, training and capital investment, but also suffers from significant traditional subtractive manufacturing waste and high logistics costs due to centralised manufacturing, with high levels of furniture product not re-cycled or re-used at the end of its life cycle. This doctoral research aims to address these problems by establishing a suitable digital manufacturing technology framework concept to create step changes in the furniture design to manufacturing pathway. The design stage has the potential to contribute massively to the environmental impact of products. In this research, a Robot Base Additive Manufacturing Concept cell for future furniture manufacturing is reported. Generative design illustrates its potential contribution to waste reduction, increased manufacturing efficiency, optimised product performance and reduced environmental impact constituting a truly lean and progressive future for Furniture Manufacturing Design. Through case studies the research will show the potential for exploiting Single Minute Exchange of Die (SMED) concepts through the rule-based AI generative design post-processing of geometry for robot manufacturing, examination of different methodologies for printing and thus the resultant potential for ‘Mass Customised’ Furniture. Aesthetics, structures and the use of Smart Materials not previously economic to manufacture will be considered to demonstrate the potential to flatten the traditional Bill of Materials (BOM) and reduce logistical issues. The Furniture Industry has developed from an artisan driven craft industry, whose pioneers saw themselves reflected in their crafts and cherished the sense of pride in the originality of their designs, now largely re-configured to an anonymous collective mass output. Digital technologies and smart materials enhancement allow innovative structural fabrication, presenting a plethora of potential for networked artisan craft industries to create extraordinary aesthetics and customisable product designs. Integrating these developments with the computing power of generative design provides the tools for practitioners to create concepts which are well beyond the insight of even the most consummate traditional designers. This framework is becoming an active area of research for application in many different industries. The step changes are empowering artisans to revolutionise the design to manufacture workflow, giving momentum to the concept of conceiving a pre-industrial model of manufacturing with bespoke sustainable design at its heart. The elements of the framework will be described and illustrated using case study models highlighting the potential for creating unique aesthetics for sustainable furniture products. The research presents the methodology to create and compare iterations employing different rule sets through a commercial generative design application and how these outputs can be further customised using parametric strategies in NURBS modellers, with the ultimate goal of creating aesthetic ‘Lean’ and sustainable innovative furniture of the future, thus illustrating how the creative use of digital networks in linking individual practitioners in the making of aesthetic customised products, manufactured local to their markets, could be achieved using this framework. This research shows a robust ‘green revolution’ is evidently necessary to satisfy the needs of an ever-growing population, allowing the world to thrive within the means of this planet. New approaches to the use of technologies can achieve these changes in Furniture Manufacturing and establish a truly enhanced Circular Economy. Governments around the World are encouraging these initiatives and these approaches are identified and rationalised alongside the drivers for change which will have major impacts on this manufacturing sector. This research critically examines the Furniture Design and Manufacturing technologies presented through a TRIZ framework against the desired outcomes. Using this approach together with the physical development of a robotic test cell, combined with case study data significant contributions to knowledge in the focused area of Furniture Manufacturing are identified, detailed and enhance Furniture Design, Manufacturing and Environmental Impact for the future. The focused approach also serves to highlight areas requiring further research

Behavior of Metallic and Composite Structures (Second Volume)

Various types of metallic and composite structures are used in modern engineering practice. For aerospace, car industry, and civil engineering applications, the most important are thin-walled structures made of di erent types of metallic alloys, brous composites, laminates, and multifunctional materials with a more complicated geometry of reinforcement including nanoparticles or nano bres. The current applications in modern engineering require analysis of structures of various properties, shapes, and sizes (e.g., aircraft wings) including structural hybrid joints, subjected to di erent types of loadings, including quasi-static, dynamic, cyclic, thermal, impact, penetration, etc.The advanced metallic and composite structures should satisfy multiple structural functions during operating conditions. Structural functions include mechanical properties such as strength, sti ness, damage resistance, fracture toughness, and damping. Non-structural functions include electrical and thermal conductivities, sensing, actuation, energy harvesting, self-healing capability, electromagnetic shielding, etc.The aim of this SI is to understand the basic principles of damage growth and fracture processes in advanced metallic and composite structures that also include structural joints. Presently, it is widely recognized that important macroscopic properties, such as macroscopic sti ness and strength, are governed by processes that occur at one to several scales below the level of observation. A thorough understanding of how these processes influence the reduction of sti ffness and strength forms the key to the design of improved innovative structural elements and the analysis of existing ones

Marks of Fire, Value and Faith. Swords with Ferrous Inlays in Finland during the Late Iron Age (ca. 700–1200 AD)

This study explores swords with ferrous inlays found in Finland and dating from the late Iron Age, ca. 700–1200 AD. These swords reflect profound changes not only in styles and fashion but also in the technology of hilts and blades. This study explores how many of these kinds of swords are known from Finland, how they were made and where, what their status was in Late Iron Age Finland, and where the Finnish finds stand in accordance with other areas of Europe. The various methods included measuring of the finds and statistics. The main method of revealing the inlaid marks was radiography due to its non-destructive nature. In cases where inlays were visible without radiography, their details were inspected via microscopy. To study the materials and manufacture of inlaid swords, a sample of them was metallographically analysed to determine the forging technologies and nature of used materials. Furthermore, the manufacture was also studied with experimental approaches. As a result, a catalogue of 151 swords with ferrous inlays was created. This number is relatively high compared with other European countries, although systematic studies have been conducted in only some countries. The inlaid motifs were classified into five distinct categories to help the classification. To summarize, almost every documented inlaid sword was unique in some respect including measurements, inlaid motifs and materials of blades and inlays. Technological variation was also present, some blades being poorer and some of higher quality in spite of the inlaid motifs. Misspelt inscriptions as well as letter-like marks were common in Finland and also in Scandinavia. Furthermore, the provenance of iron and steel used in some blades hints at Scandinavian ores. The above observations, along with the experimental results indicating the existence of multiple alternative techniques of inlaying, suggest that these swords were manufactured locally in Scandinavia, most likely in imitation of Continental European models. Inlaid swords were valued partly for their assumed functionality in combat, as evidenced by damage on some examined blades, or they were valued for their inlays, which could have had fashionable or symbolical meanings bound to local beliefs.Tässä työssä tarkastellaan Suomen alueelta löydettyjä, rautaisin merkein varustettuja miekkoja, jotka ajoittuvat nuoremmalle rautakaudelle (n. 700–1200 jKr.). Näissä miekoissa kuvastuvat paitsi tyylien ja muotojen muutokset, myös miekkojen eri osien teknologinen kehitys. Tässä työssä selvitetään, kuinka monta tällaista ns. säiläkirjoitusmiekkaa on löydetty Suomesta, kuinka ja missä niitä oli saatettu valmistaa, mikä niiden merkitys oli nuoremman rautakauden Suomessa, ja miten Suomen aineisto on vertailtavissa vastaaviin löytöihin muualta Euroopasta. Perusmenetelmät olivat aineiston mittaaminen ja tilastointi. Röntgenkuvausta käytettiin pääasiallisena menetelmänä säilämerkkien paljastamiseksi, koska tämä ei vahingoittanut löytöjä. Tapauksissa, joissa säilämerkit olivat näkyvissä paljaalla silmällä, tutkittiin niiden yksityiskohtia mikroskoopin avulla. Säiläkirjoitusmiekkojen materiaaleja sekä valmistusteknisiä kysymyksiä lähestyttiin metallografisilla analyyseilla, joita käytettiin pieneen otokseen löytöaineistosta. Lisäksi miekkojen sekä säilämerkkien valmistusta tutkittiin kokeellisen arkeologian keinoin. Aineiston tutkimuksen tuloksena oli 151 säilämerkein varustettua miekkalöytöä käsittävä katalogi. Tämä säiläkirjoitusmiekkojen määrä on suuri verrattuna muihin Euroopan maihin, vaikkakin systemaattisia tutkimuksia säiläkirjoitusmiekoista on tehty vain vähän. Säilämerkit luokiteltiin viiteen kategoriaan aineiston jäsentämiseksi ja luokittelun helpottamiseksi. Työssä esitellystä aineistosta lähes jokainen oli uniikki ottaen huomioon mitat, säilämerkkien sisällön, sekä säilän ja merkkien materiaalit. Teknologista variaatiota esiintyi myös säilissä riippumatta säilämerkkien sisällöstä. Väärin kirjoitetut tekstit sekä kirjaimia imitoivat kuviot näyttävät olleen yleisiä sekä Suomessa että Skandinaviassa. Lisäksi säiliin ja merkkeihin käytetyn raudan alkuperä viittaa joissakin tapauksissa skandinaavisiin malmiesiintymiin. Ylläolevat havainnot sekä kokeellisen tutkimuksen ehdottamat, useat mahdolliset säilämerkkien valmistustekniikat antavat olettaa, että näitä miekkoja valmistettiin paikallisesti Skandinaviassa, mahdollisesti imitoiden mannereurooppalaisia malleja. Säiläkirjoitusmiekkoja pidettiin arvossa osaksi niiden oletetun taistelukestävyyden vuoksi, kuten säilissä ilmenevät iskujäljet todistavat. Osittain näitä miekkoja arvostettiin niiden sisältämien merkkien vuoksi, jotka saattoivat liittyä muotiin, symboliikkaan tai uskomuksiin jopa paikallisella tasolla.Siirretty Doriast

Digital Fabrication of Frequency Selective Surfaces for In-Building Applications Using Inkjet Printing Technology

This thesis presents work on the inkjet printing manufacture of frequency selective surfaces intended for in-building applications using silver nanoparticle inks. The aim of this research is to investigate the performance of inkjet printed FSS panels in terms of transmission response, element conductivity, and the resolution of the printed lines, all of which are produced efficiently in terms of cost and resource usage. Different FSS design were investigated from simple elements such as linear dipoles, square loops and convoluted square loop elements. Various techniques were used in the manufacturing process such as different ink drop spacing, number of jetted ink layers, and different sintering methods, with the aim of achieving low cost manufacturing with a reduced amount of deposited silver inks and sintering time and temperature. Additionally, further reductions in the deposited ink were considered by the introduction of frame elements. The research also focuses on factors that could affect the transmittivity/reflectivity of the FSS screen, such as the influence of imperfections in the printed elements. The imperfections are expected in the case of low cost mass production, therefore it is important to understand to what extent they could be tolerated whilst still providing adequate performance. Finally, the work also considers developing novel slotted FSS arrays operating at low frequency bands such as the TETRA emergency band and suitable for additive manufacturing

Research and development of graphene-based supercapacitors through Graphene Oxide

Supercapacitors (SCs) are energy storage devices suited for high power applications. Due to their growing interest, researchers are looking for their improvement in both performances and scalabililty, including the environmetal impact. In this PhD thesis, after an overview about different SCs and their main lines of research, author's works about innovative graphene-based elecrodes are discussed. In particular, the study and the use of a graphene precursor, Graphene Oxide, are the central elements of such researches