•Street-level photographs are now an omnipresent urban dataset.•Buildings are often imaged multiple times, but most photos are obstructed.•An approach to generate 3D models of buildings from their ...single views.•The method can be aided by building footprints.•The resulting models are usable for a variety of use cases.
3D building models are an established instance of geospatial information in the built environment, but their acquisition remains complex and topical. Approaches to reconstruct 3D building models often require existing building information (e.g.their footprints) and data such as point clouds, which are scarce and laborious to acquire, limiting their expansion. In parallel, street view imagery (SVI) has been gaining currency, driven by the rapid expansion in coverage and advances in computer vision (CV), but it has not been used much for generating 3D city models. Traditional approaches that can use SVI for reconstruction require multiple images, while in practice, often only few street-level images provide an unobstructed view of a building. We develop the reconstruction of 3D building models from a single street view image using image-to-mesh reconstruction techniques modified from the CV domain. We regard three scenarios: (1) standalone single-view reconstruction; (2) reconstruction aided by a top view delineating the footprint; and (3) refinement of existing 3D models, i.e.we examine the use of SVI to enhance the level of detail of block (LoD1) models, which are common. The results suggest that trained models supporting (2) and (3) are able to reconstruct the overall geometry of a building, while the first scenario may derive the approximate mass of the building, useful to infer the urban form of cities. We evaluate the results by demonstrating their usefulness for volume estimation, with mean errors of less than 10% for the last two scenarios. As SVI is now available in most countries worldwide, including many regions that do not have existing footprint and/or 3D building data, our method can derive rapidly and cost-effectively the 3D urban form from SVI without requiring any existing building information. Obtaining 3D building models in regions that hitherto did not have any, may enable a number of 3D geospatial analyses locally for the first time.
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The incorporation of 3D printing technologies in the pharmaceutical industry can revolutionize its R&D, by providing a simple and rapid method to produce tailored one-off batches, ...each with customized dosages, different compounds, shapes, sizes, and adjusted release rates. Particularly, this type of technology can be advantageous for the development of topical and transdermal drug delivery systems, including patches and microneedles. The use of both systems as drug carriers offers advantages over the oral administration, but the possibility of skin irritation and sensitization, and the high production costs, may hinder the expansion of this market. In this context, 3D printing, a high-resolution technique, allows the design of high quality, personalized, complex and sophisticated structures, thus reducing the production costs and improving the patient compliance. This review covers the 3D printing concept and discusses the relevance of this technology to the pharmaceutical industry, with a special focus on the development of topical and transdermal products - patches and microneedles. The potential of 3D bioprinting for skin applications is also presented, highlighting the development of patch-like skin constructs for wound and burn treatment, and skin equivalents for in vitro research and drug development. Several recent studies were selected to support the relevance of the subjects addressed herein. Additionally, the limitations of these printing technologies are discussed, including regulatory, quality and safety issues.
Purpose
Printing technology, capable of producing three‐dimensional (3D) objects, has evolved in recent years and provides potential for developing reproducible and sophisticated physical phantoms. ...3D printing technology can help rapidly develop relatively low cost phantoms with appropriate complexities, which are useful in imaging or dosimetry measurements. The need for more realistic phantoms is emerging since imaging systems are now capable of acquiring multimodal and multiparametric data. This review addresses three main questions about the 3D printers currently in use, and their produced materials. The first question investigates whether the resolution of 3D printers is sufficient for existing imaging technologies. The second question explores if the materials of 3D‐printed phantoms can produce realistic images representing various tissues and organs as taken by different imaging modalities such as computer tomography (CT), positron emission tomography (PET), single‐photon emission computed tomography (SPECT), magnetic resonance imaging (MRI), ultrasound (US), and mammography. The emergence of multimodal imaging increases the need for phantoms that can be scanned using different imaging modalities. The third question probes the feasibility and easiness of “printing” radioactive or nonradioactive solutions during the printing process.
Methods
A systematic review of medical imaging studies published after January 2013 is performed using strict inclusion criteria. The databases used were Scopus and Web of Knowledge with specific search terms. In total, 139 papers were identified; however, only 50 were classified as relevant for this paper. In this review, following an appropriate introduction and literature research strategy, all 50 articles are presented in detail. A summary of tables and example figures of the most recent advances in 3D printing for the purposes of phantoms across different imaging modalities are provided.
Results
All 50 studies printed and scanned phantoms in either CT, PET, SPECT, mammography, MRI, and US—or a combination of those modalities. According to the literature, different parameters were evaluated depending on the imaging modality used. Almost all papers evaluated more than two parameters, with the most common being Hounsfield units, density, attenuation and speed of sound.
Conclusions
The development of this field is rapidly evolving and becoming more refined. There is potential to reach the ultimate goal of using 3D phantoms to get feedback on imaging scanners and reconstruction algorithms more regularly. Although the development of imaging phantoms is evident, there are still some limitations to address: One of which is printing accuracy, due to the printer properties. Another limitation is the materials available to print: There are not enough materials to mimic all the tissue properties. For example, one material can mimic one property—such as the density of real tissue—but not any other property, like speed of sound or attenuation.
Monolithic three-dimensional (M3D) integration allows ultra-thin silicon tier stacking in a single package. The high-density stacking is acquiring interest and is becoming more popular for smaller ...footprint areas, shorter wirelength, higher performance, and lower power consumption than the conventional planar fabrication technologies. The physical design of M3D integrated circuits requires several design steps, such as three-dimensional (3D) placement, 3D clock-tree synthesis, 3D routing, and 3D optimization. Among these, 3D routing is significantly time consuming due to countless routing blockages. Therefore, 3D routers proposed in the literature insert monolithic interlayer vias (MIVs) and perform tier-by-tier routing in two substeps. In this article, we propose an algorithm to build a routing topology database (DB) used to construct all multilayer monolithic rectilinear Steiner minimum trees on the 3D Hanan grid. To demonstrate the effectiveness of the DB in various applications, we use the DB to construct timing-driven 3D routing topologies and perform congestion-aware global routing on 3D designs. We anticipate that the algorithm and the DB will help 3D routers reduce the runtime of the MIV insertion step and improve the quality of the 3D routing.
We first synthesized a 3D hierarchical CoWO4/Co3O4 nanowire arrays material for supercapacitors. The 3D CoWO4/Co3O4//AC ASCs device shows high energy density and power density.
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•We ...first found that CoWO4 and 3D CoWO4/Co3O4 exhibit four pairs of redox peaks and discussed it systematically.•We first synthesized a 3D CoWO4/Co3O4 nanowire arrays materials.•The integration of CoWO4 enhances the activity of the redox reaction.•The 3D CoWO4/Co3O4//AC ASCs device shows high energy density and power density.
A 3D hierarchical CoWO4/Co3O4 structure, with the synergetic effect of diverse materials, large specific surface area and fast transmission of electrons and ions is synthesized by a facile and efficient microwave hydrothermal method. We found that CoWO4 and 3D CoWO4/Co3O4 exhibit four pairs of redox peaks, which were discussed systematically. The hybrid electrode shows excellent specific capacitance of 1728 F g−1 at current density of 2.7 mA cm−2 (1 A g−1) with superior rate capability and satisfactory cycling stability (85.9% capacitance preserved after 5000 cycles). The asymmetric supercapacitors assembled with CoWO4/Co3O4 and activated carbon exhibit high energy density (57.8 Wh kg−1) and power density (6000 W kg−1 at 40.64 Wh kg−1), with remarkable cycle life. The above results indicate that the ordered CoWO4/Co3O4 nanowire arrays synthesized by this approach would be a promising candidate for practical application of high-performance supercapacitors.
Measurement of tensile bond strength of 3D printed geopolymer mortar Panda, Biranchi; Paul, Suvash Chandra; Mohamed, Nisar Ahamed Noor ...
Measurement : journal of the International Measurement Confederation,
January 2018, 2018-01-00, 20180101, Volume:
113
Journal Article
Peer reviewed
Open access
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•The central concept of 3D concrete printing was described.•A novel fly ash based geopolymer mortar was formulated for large scale concrete printing application.•Fresh and hardened ...properties were characterized for printability of geopolymer mortar.•Tensile bond strength of the printed geopolymer was evaluated with respect to printing parameters.
The structural capacity of construction joints in concrete bridges, deck and pavements mainly depends on the bond strength between the old substrate and new overlaid concrete. Sometimes, a mismatch in the properties of old and new concrete may lead to early age failure and shortened service life. Since in 3D concrete printing (3DCP), the whole object is made by layer by layer, bond strength is considered as one of the key parameters to ensure stability in the structure. For understanding bond mechanism, it is essential to measure bond strength at the interface between new and old layer and investigate significant parameters affecting this property. In this direction, our current work targets to analyse tensile bond strength of 3D printed geopolymer mortar with respect to printing time gap between layers, nozzle speed and nozzle standoff distance. A novel formulation of fly ash based geopolymer was made and printed using four-axis automated gantry system. Experimental findings reveal that the bond strength is a function of state of interface material between two nearby layers which can be influenced by material strength development rate and 3D printing parameters.
Bone tissue engineering approaches have evolved towards addressing the challenges of tissue mimetic requirements over the years. Different strategies have been combining scaffolds, cells, and ...biologically active cues using a wide range of fabrication techniques, envisioning the mimicry of bone tissue. On the one hand, biomimetic scaffold-based strategies have been pursuing different biomaterials to produce scaffolds, combining with diverse and innovative fabrication strategies to mimic bone tissue better, surpassing bone grafts. On the other hand, biomimetic scaffold-free approaches mainly foresee replicating endochondral ossification, replacing hyaline cartilage with new bone. Finally, since bone tissue is highly vascularized, new strategies focused on developing pre-vascularized scaffolds or pre-vascularized cellular aggregates have been a motif of study. The recent biomimetic scaffold-based and scaffold-free approaches in bone tissue engineering, focusing on materials and fabrication methods used, are overviewed herein. The biomimetic vascularized approaches are also discussed, namely the development of pre-vascularized scaffolds and pre-vascularized cellular aggregates.
•Bone tissue engineering approaches envision to mimic tissue requirements.•Biodegradable materials, cells, and biologically active cues have been combined using different techniques to reach such requirements.•Recent biomimetic scaffold-based and scaffold-free strategies aiming for bone tissue engineering are overviewed herein.•Also, biomimetic vascularized approaches are discussed.
Diversified printing mechanism and various applicable materials endow 3D printing technology with a wide range of applications in catalysis. Hence, the purpose of this review is to provide a general ...overview of various 3D printing strategies and catalytic applications, and future outlook towards the catalysis field.
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•Various 3D printing strategies and mechanisms are introduced.•Applications of 3D printing in catalysis are reviewed.•The prospect and challenges of 3D printing in catalysis are expected.
Three-dimensional (3D) printing is changing the way of designing and manufacturing 3D objects by transforming digital models into solid models. 3D printing, known as a revolutionary additive manufacturing, also has an impact on catalysis with its continuous progress. Currently, 3D printing technology is widely combined with some related catalytic reactions and processes. Different from the traditional manufacture mode, the computer-aided digital and intelligent manufacturer makes the research on monolithic catalysts, reactors, mixers and ancillaries more in-depth. 3D printing gives more diversity and provides broader applications for catalysis. This review mainly introduces different 3D printing technologies, processes and printing mechanisms, and epitomizes their research and applications in the field of catalysis.
Biodegradable polyesters have been extensively used for preparation of nerve guidance scaffolds, due to their high biocompatibility and defined degradation periods. However, conventional methods for ...fabrication of porous polyester scaffolds provide limited control over shape and micro-architecture. Here, a fabrication procedure based on 3D printing was developed to generate highly ordered and anatomically personalized, polyester scaffolds for soft tissue regeneration. Scaffolds composed of Poly-lactic-glycolic acid (PLGA) and poly-L-lactic acid (PLLA) were specifically customized for nerve injuries. This was obtained by using an oriented multi-layer printing pattern which established a linear structure in the fabricated scaffolds to match the aligned topography of nerve tissues. The oriented scaffold was shown to guide regenerating axons to linear conformations and support growth of induced pluripotent stem cell-derived neurons in vitro and in vivo in a model of spinal cord injury. The described scaffolds may advance the field of nerve regeneration. Furthermore, modifications could be integrated to generate soft implants for various types of tissues.
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