New Trends in 3D Printing

A quarter century period of the 3D printing technology development affords ground for speaking about new realities or the formation of a new technological system of digital manufacture and partnership. The up-to-date 3D printing is at the top of its own overrated expectations. So the development of scalable, high-speed methods of the material 3D printing aimed to increase the productivity and operating volume of the 3D printing machines requires new original decisions. It is necessary to study the 3D printing applicability for manufacturing of the materials with multilevel hierarchical functionality on nano-, micro- and meso-scales that can find applications for medical, aerospace and/or automotive industries. Some of the above-mentioned problems and new trends are considered in this book

Review on Active and Passive Remote Sensing Techniques for Road Extraction

Digital maps of road networks are a vital part of digital cities and intelligent transportation. In this paper, we provide a comprehensive review on road extraction based on various remote sensing data sources, including high-resolution images, hyperspectral images, synthetic aperture radar images, and light detection and ranging. This review is divided into three parts. Part 1 provides an overview of the existing data acquisition techniques for road extraction, including data acquisition methods, typical sensors, application status, and prospects. Part 2 underlines the main road extraction methods based on four data sources. In this section, road extraction methods based on different data sources are described and analysed in detail. Part 3 presents the combined application of multisource data for road extraction. Evidently, different data acquisition techniques have unique advantages, and the combination of multiple sources can improve the accuracy of road extraction. The main aim of this review is to provide a comprehensive reference for research on existing road extraction technologies.Peer reviewe

3D registration and integrated segmentation framework for heterogeneous unmanned robotic systems

The paper proposes a novel framework for registering and segmenting 3D point clouds of large-scale natural terrain and complex environments coming from a multisensor heterogeneous robotics system, consisting of unmanned aerial and ground vehicles. This framework involves data acquisition and pre-processing, 3D heterogeneous registration and integrated multi-sensor based segmentation modules. The first module provides robust and accurate homogeneous registrations of 3D environmental models based on sensors' measurements acquired from the ground (UGV) and aerial (UAV) robots. For 3D UGV registration, we proposed a novel local minima escape ICP (LME-ICP) method, which is based on the well known iterative closest point (ICP) algorithm extending it by the introduction of our local minima estimation and local minima escape mechanisms. It did not require any prior known pose estimation information acquired from sensing systems like odometry, global positioning system (GPS), or inertial measurement units (IMU). The 3D UAV registration has been performed using the Structure from Motion (SfM) approach. In order to improve and speed up the process of outliers removal for large-scale outdoor environments, we introduced the Fast Cluster Statistical Outlier Removal (FCSOR) method. This method was used to filter out the noise and to downsample the input data, which will spare computational and memory resources for further processing steps. Then, we co-registered a point cloud acquired from a laser ranger (UGV) and a point cloud generated from images (UAV) generated by the SfM method. The 3D heterogeneous module consists of a semi-automated 3D scan registration system, developed with the aim to overcome the shortcomings of the existing fully automated 3D registration approaches. This semi-automated registration system is based on the novel Scale Invariant Registration Method (SIRM). The SIRM provides the initial scaling between two heterogenous point clouds and provides an adaptive mechanism for tuning the mean scale, based on the difference between two consecutive estimated point clouds' alignment error values. Once aligned, the resulting homogeneous ground-aerial point cloud is further processed by a segmentation module. For this purpose, we have proposed a system for integrated multi-sensor based segmentation of 3D point clouds. This system followed a two steps sequence: ground-object segmentation and color-based region-growing segmentation. The experimental validation of the proposed 3D heterogeneous registration and integrated segmentation framework was performed on large-scale datasets representing unstructured outdoor environments, demonstrating the potential and benefits of the proposed semi-automated 3D registration system in real-world environments

Advances in Unconventional Lithography

The term Lithography encompasses a range of contemporary technologies for micro and nano scale fabrication. Originally driven by the evolution of the semiconductor industry, lithography has grown from its optical origins to demonstrate increasingly fine resolution and to permeate fields as diverse as photonics and biology. Today, greater flexibility and affordability are demanded from lithography more than ever before. Diverse needs across many disciplines have produced a multitude of innovative new lithography techniques. This book, which is the final instalment in a series of three, provides a compelling overview of some of the recent advances in lithography, as recounted by the researchers themselves. Topics discussed include nanoimprinting for plasmonic biosensing, soft lithography for neurobiology and stem cell differentiation, colloidal substrates for two-tier self-assembled nanostructures, tuneable diffractive elements using photochromic polymers, and extreme-UV lithography

Process planning for robotic wire ARC additive manufacturing

Robotic Wire Arc Additive Manufacturing (WAAM) refers to a class of additive manufacturing processes that builds parts from 3D CAD models by joining materials layerupon- layer, as opposed to conventional subtractive manufacturing technologies. Over the past half century, a significant amount of work has been done to develop the capability to produce parts from weld deposits through the additive approach. However, a fully automated CAD-topart additive manufacturing (AM) system that incorporates an arc welding process has yet to be developed. The missing link is an automated process planning methodology that can generate robotic welding paths directly from CAD models based on various process models. The development of such a highly integrated process planning method for WAAM is the focus of this thesis

The development of a business model innovation framework from a value network perspective applied to the prospective cemented tungsten carbide additive manufacturing sector in South Africa

Thesis (MEng)--Stellenbosch University, 2022.ENGLISH ABSTRACT: The adoption and implementation of Industry 4.0 technologies lead to numerous opportunities and challenges for small, medium, and micro enterprises (SMMEs), which form an important part of the manufacturing industry and the South African economy. One such technology is additive manufacturing (AM) that enables the production and delivery of new products and services. Since SMMEs are often characterised by a lack of finance, capacity, resources, and competencies, it is imperative to form part of value networks. These intentionally formed value networks, referred to in this study as strategic business nets, aim to gain or sustain a competitive advantage through collaboration among competitors to increase capacity, co-operation with customers to develop focused competencies, and collaboration with partners that provide access to complementary competencies and resources. For SMMEs, the configuration of these strategic business nets remains challenging, as well as the ability to develop applicable networked business models to create, deliver, and capture value. Therefore, SMMEs require guidance to adopt new principles in transforming their business models from the firm-level to the network-level, referred to as networked business model innovation. The aim of this study was to systematically develop a business model innovation framework from a value network perspective to support SMMEs to configure strategic business nets and develop appropriate networked business models. Furthermore, this study was focused on the application value of such a management framework and tool to the cemented tungsten carbide manufacturing industry of South Africa with a view to incorporate additive manufacturing into the sector via SMMEs. Although the use of AM techniques to produce tungsten carbide products is still an emerging research field, business related research is of utmost importance to support industry development and strengthening. Since SMMEs often cannot afford comprehensive external advisory services, lack guidance in business restructuring amidst disruptive change, and lack mature and systematic development procedures, it is imperative to focus research studies to develop self-explanatory methods and tools to guide the strategic development and growth of these SMMEs. The management framework and tool were developed, refined, and evaluated through multiple design cycle iterations, as informed by the Design Science Research Framework. Various aspects, including frameworks, concepts, elements, and activities were obtained from the business model, business model innovation and value network literature domains. Furthermore, insights were obtained from various subject-matter experts within the business, manufacturing, and AM industries. As part of the management framework, a value network visualisation or mapping tool was developed, referred to as the strategic business net configuration process, to enable users to visualise the configuration of future strategic business nets. To demonstrate the framework’s applicability and capacity to support the prospective cemented tungsten AM industry of South Africa, a type of case study was conducted. The findings and insights obtained could provide potential support for future users and key role players within the industry to build upon. Finally, the management framework was converted into a management tool using online, collaborative software that could be used by manufacturing SMMEs, or entrepreneurs that want to enter an emerging technology market.AFRIKAANSE OPSOMMING: Die aanvaarding en implementering van Industrie 4.0 tegnologieë lei tot talle geleenthede en uitdagings vir klein, medium en mikro-ondernemings (KMMO's), wat ‘n belagrike rol speel in die vervaardigingsbedryf en die Suid-Afrikaanse ekonomie ondersteun. Een van hierdie tegnologieë is additive manufacturing wat die produsering en lewering van nuwe produkte en dienste moontlik maak. Aangesien KMMO's soms gekniehalter word deur 'n gebrek aan finansiering, kapasiteit, hulpbronne en bevoegdhede, is dit noodsaaklik dat hulle deel vorm van waardenetwerke. Hierdie doelbewus gevormde waardenetwerke, soos na verwys in hierdie studie as strategiese sakenette, het ten doel om 'n mededingende voordeel te verkry of te behou deur samewerking met mededingers om kapasiteit te verhoog, samewerking met kliënte om spesifieke bevoegdhede te ontwikkel, asook samewerking met vennote wat toegang bied tot aanvullende bevoegdhede en hulpbronne. Die ontwikkeling van hierdie strategiese sakenette bly vir KMMNO’s uitdagend, sowel as die vermoë om toepaslike netwerk-gebaseerde besigheidsmodelle te ontwikkel. Daarom benodig KMMO's leiding om nuwe besigheidsbeginsels aan te neem en om hulle besigheidsmodelle te omskep vanaf die besigheidsvlak na die netwerkvlak, waarna verwys word in hierdie studie as netwerk gebaseerde besigheidsmodelinnovasie. Die primêre doel van hierdie studie was om sistematies 'n besigheidsmodelinnovasieraamwerk te ontwikkel vanuit 'n waardenetwerk perspektief om KMMO's te ondersteun in die ontwikkeling van strategiese sakenette asook gepaste netwerk gebaseerde besigheidsmodelle. Verder was hierdie studie spesifiek gefokus op die toepassingswaarde van so 'n bestuursraamwerk en hulpmiddel op die potensiële gebruik van additive manufacturing in die vervaardigingsindustrie van gesementeerde wolframkarbiede (cemented tungsten carbide) produkte in Suid-Afrika. Alhoewel die gebruik van additive manufacturing tegnieke vir die vervaardiging van wolframkarbiede produkte steeds 'n opkomende navorsingsveld is, is besigheidsverwante navorsing van uiterste belang ten einde die ontwikkeling van die bedryf te ondersteun. Aangesien KMMO's dikwels nie eksterne adviesdienste kan bekostig nie, sukkel met herstrukturering, en 'n tekort het aan ontwikkelingsprosedures, is dit noodsaaklik om navorsingstudies oor selfverduidelikende metodes en hulpmiddels te doen om by te dra tot die strategiese ontwikkeling en groei van hierdie KMMO's. Die bestuursraamwerk en hulpmiddel is ontwikkel, verfyn en geëvalueer deur middel van verskeie ontwerpsiklusse, soos voorgestel deur die Design Science Research raamwerk. Verskeie aspekte, insluitende teoretiese raamwerke, konsepte, elemente en aktiwiteite, is verkry uit die besigheidsmodel, besigheidsmodelinnovasie en waardenetwerke literatuurdomeine. Verder is insig verkry vanaf verskillende vakdeskundiges in die besigheids en-vervaardigings-bedrywe. 'n Waardevisualiseringshulpmiddel is ontwikkel as deel van die bestuursraamwerk, waarna verwys word in hierdie studie as die strategic business model configuration process, om gebruikers te help om strategiese sakenette te visualiseer op strategiese en taktiese vlakke. ‘n Gevallestudie is gedoen om die toepaslikheid van die raamwerk te demonstreer. Die fokus was op die potensiële gebruik van additive manufacturing om gesementeerde wolfraamprodukte in die gereedskap industrie in Suid-Afrika te vervaardig. Die bevindinge wat gemaak is en insigte wat verkry is, kan potensieël ondersteuning bied aan toekomstige gebruikers en belangrike rolspelers in die bedryf om op voort te bou. Uiteindelik is die bestuursraamwerk omskep in 'n bestuurshulpmiddel met behulp van aanlyn sagteware wat gebruik kan word deur KMMO's, of entrepreneurs wat 'n opkomende tegnologiemark wil betree.Master

Quantitative Evaluation of Pulmonary Emphysema Using Magnetic Resonance Imaging and x-ray Computed Tomography

Chronic obstructive pulmonary disease (COPD) is a leading cause of morbidity and mortality affecting at least 600 million people worldwide. The most widely used clinical measurements of lung function such as spirometry and plethysmography are generally accepted for diagnosis and monitoring of the disease. However, these tests provide only global measures of lung function and they are insensitive to early disease changes. Imaging tools that are currently available have the potential to provide regional information about lung structure and function but at present are mainly used for qualitative assessment of disease and disease progression. In this thesis, we focused on the application of quantitative measurements of lung structure derived from 1H magnetic resonance imaging (MRI) and high resolution computed tomography (CT) in subjects diagnosed with COPD by a physician. Our results showed that significant and moderately strong relationship exists between 1H signal intensity (SI) and 3He apparent diffusion coefficient (ADC), as well as between 1H SI and CT measurements of emphysema. This suggests that these imaging methods may be quantifying the same tissue changes in COPD, and that pulmonary 1H SI may be used effectively to monitor emphysema as a complement to CT and noble gas MRI. Additionally, our results showed that objective multi-threshold analysis of CT images for emphysema scoring that takes into account the frequency distribution of each Hounsfield unit (HU) threshold was effective in correctly classifying the patient into COPD and healthy subgroups. Finally, we found a significant correlation between whole lung average subjective and objective emphysema scores with high inter-observer agreement. It is concluded that 1H MRI and high resolution CT can be used to quantitatively evaluate lung tissue alterations in COPD subjects

Fabrication Of Functional Nanostructures Using Polyelectrolyte Nanocomposites And Reduced Graphene Oxide Assemblies

A wide variety of nanomaterials ranging from polymer assemblies to organic and inorganic nanostructures (particles, wires, rods etc) have been actively pursued in recent years for various applications. The synthesis route of these nanomaterials had been driven through two fundamental approaches - \u27Top down\u27 and \u27Bottom up\u27. The key aspect of their application remained in the ability to make the nanomaterials suitable for targeted location by manipulating their structure and functionalizing with active target groups. Functional nanomaterials like polyelectrolyte based multilayered thin films, nanofibres and graphene based composite materials are highlighted in the current research. Multilayer thin films were fabricated by conventional dip coating and newly developed spray coating techniques. Spray coating technique has an advantage of being applied for large scale production as compared to the dip coating technique. Conformal hydrophobic/hydrophilic and superhydrophobic/hydrophilic thermal switchable surfaces were fabricated with multilayer films of poly(allylaminehydrochloride) (PAH) and silica nanoparticles by the dip coating technique, followed by the functionalization with thermosensitive polymer-poly(N-isopropylacrylamide)(PNIPAAM) and perfluorosilane. The thermally switchable superhydrophobic/ hydrophilic polymer patch was integrated in a microfluidic channel to act as a stop valve. At 70 degree centigrade, the valve was superhydrophobic and stopped the water flow (close status) while at room temperature, the patch became hydrophilic, and allowed the flow (open status). Spray-coated multilayered film of poly(allylaminehydrochloride) (PAH) and silica nanoparticles was fabricated on polycarbonate substrate as an anti-reflection (AR) coating. The adhesion between the substrate and the coating was enhanced by treating the polycarbonate surface with aminopropyltrimethoxylsilane (APTS) and sol-gel. The coating was finally made abrasion-resistant with a further sol-gel treatment on top of AR coating, which formed a hard thin scratch-resistant film on the coating. The resultant AR coating could reduce the reflection from 5 to 0.3% on plastic. Besides multilayered films, the fabrication of polyelectrolyte based electrospun nanofibers was also explored. Ultrathin nanofibers comprising 2-weak polyelectrolytes, poly(acrylic acid) (PAA) and poly(allylaminehydrochloride) (PAH) were fabricated using the electrospinning technique and methylene blue (MB) was used as a model drug to evaluate the potential application of the fibers for drug delivery. The release of MB was controlled in a nonbuffered medium by changing the pH of the solution. Temperature controlled release of MB was obtained by depositing temperature sensitive PAA/poly(N-isopropylacrylamide) (PNIPAAM) multilayers onto the fiber surfaces. The sustained release of MB in a phosphate buffered saline (PBS) solution was achieved by constructing perfluorosilane networks on the fiber surfaces as capping layers. The fiber was also loaded with a real life anti-depressant drug (2,3-tertbutyl-4-methoxyphenol) and fiber surface was made superhydrophobic. The drug loaded superhydrophobic nanofiber mat was immersed under water, phosphate buffer saline and surfactant solutions in three separated experiments. The rate of release of durg was monitored from the fiber surface as a result of wetting with different solutions. Time dependent wetting of the superhydrophobic surface and consequently the release of drug was studied with different concentrations of surfactant solutions. The results provided important information about the underwater superhydrophobicity and retention time of drug in the nanofibers. The nanostructured polymers like nanowires, nanoribbons and nanorods had several other applications too, based on their structure. Different self-assembled structures of semiconducting polymers showed improved properties based on their architectures. Poly(3-hexylthiophene) (P3HT) supramolecular structures were fabricated on P3HT-dispersed reduced graphene oxide (RGO) nanosheets. P3HT was used to disperse RGO in hot anisole/N, N-dimethylformamide solvents, and the polymer formed nanowires on RGO surfaces through a RGO induced crystallization process. The Raman spectroscopy confirmed the interaction between P3HT and RGO, which allowed the manipulation of the composite\u27s electrical properties. Such a bottom-up approach provided interesting information about graphene-based composites and inspired to study the interaction between RGO and the molecular semiconductor-tetrasulphonate salt of copper phthalocyanine (TSCuPc) for nanometer-scale electronics. The reduction of graphene oxide in presence of TSCuPc produced a highly stabilized aqueous composite ink with monodispersed graphene sheets. To demonstrate the potential application of the donor (TSCuPc)\u27acceptor (graphene) composite, the RGO/TSCuPc suspension was successfully incorporated in a thin film device and the optoelectronic property was measured. The conductivity (dark current) of the composite film decreased compared to that of pure graphene due to the donor molecule incorporation, but the photoconductivity and photoresponsivity increased to an appreciable extent. The property of the composite film overall improved with thermal annealing and optimum loading of TSCuPc molecules