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The promising routes of metallic additive manufacturing favor the fabrication of refined functional components. Nonetheless, dealing with the Laser Powder Bed Fusion (L-PBF) parameters and costs for making the most of this technology is still an issue. The challenge gets bigger when considering less explored parameters, such as the process atmosphere and build location. So, this study aimed to address the main differences in microstructure, crystallography, mechanical properties, and surface finishing of maraging steel components manufactured under two different atmospheres (N2 and a mixture of 75%Ar-25%He atmospheres) and three build locations arranged along the gas flow direction. Based on experimental characterizations, the porosity fraction, microstructural constituents and metallurgical flaws, phase composition and martensite matrix crystallographic parameters, macrotexture, mechanical properties, roughness, and surface residual stress were investigated and compared for the different manufacturing conditions. The porosity fraction had the most expressive changes with the gas type and the build location, reaching a 53% overall reduction under N2 and a 112 to 302% rise for the front located sample compared to the others. The underlying mechanisms involved in the observed results, mainly related to process by-products behavior, were discussed. Broadly, the N2 atmosphere stands out over the analyzed properties. These findings underscore the role of atmospheric selection in the LPBF process, considering the overall quality and performance of the fabricated material and the possibility of cost reduction. [ABSTRACT FROM AUTHOR]

We present a sensor array of microscale organic electrochemical transistors (OECTs) using poly (3,4−ethylenedioxythiophene):poly(styrenesulfonic acid) (PEDOT:PSS) as the channel material. The devices show high sensitivity and selectivity to detect dopamine (DA) with platinum (Pt) as a pseudo−reference gate electrode. First, we describe the wafer−scale fabrication process for manufacturing the PEDOT:PSS OECTs, and then we introduce a dilution method to adjust the thickness of the PEDOT:PSS film. Next, we investigate the effect of the film thickness on the sensitivity of DA detection. Reducing the film thickness enhances the sensitivity of DA detection within the concentration range of 1 μM to 100 μM. The OECTs show impressive sensitivitywith a limit of detection (LoD) as low as 1 nM and a high selectivity against uric acid (UA) and ascorbic acid (AA). Finally, we modify the surface of the Pt gate electrode with chitosan to improve the selectivity of OECTs at high concentrations of up to 100 µM to expand the detection range. [ABSTRACT FROM AUTHOR]

Additive manufacturing technology has fostered its significant application in soft robotics fabrication due to the design freedom and ease of realizing complex geometries. The selection of an appropriate additive manufacturing process (out-of-material extrusion, vat photopolymerization, and powder bed fusion) is vital for the fabrication of soft robotics as the process greatly influences the quality of the part further affecting the functionality and service life. These pneumatically actuated robots in their service life are subjected to fatigue loading and handling of very delicate tasks; thus, the porosity (including pores characterization) and surface roughness are two critical quality parameters which should be considered while choosing the fabrication process. In this study, a three-way decision-making (a multi-criteria decision-making tool) approach is implemented for selecting an appropriate additive manufacturing process for the fabrication of high-quality parts for soft robotics applications. The results (ranking of AM processes) obtained using the proposed approach are compared with the conventional decision-making techniques, namely TOPSIS (Technique for Order of Preference by Similarity to Ideal Solution), MOORA (Multi-Objective Optimization by Ratio Analysis), and VIKOR (VIseKriterijumska Optimizacija). The sensitivity analysis carried out in this work also suggests that three-way decision-making is as effective as other MCDM tools and the vat photopolymerization process is the most suitable out of all for fabricating TPU actuators. [ABSTRACT FROM AUTHOR]

The article focuses on the complex construction and fabrication process of "light eyes" for the Stuttgart 21 underground train station, aiming to provide ample daylight using a combination of structurally demanding concrete support columns. Topics include the challenging welding process, the selection of optimal preheating techniques, and the implementation of deep induction heating for efficient and reliable welding, ensuring the success of the ambitious construction project.

Magnetic nanoparticles (MNPs) in a suspension have been shown to change resistance by an order of magnitude based on an applied field. We have prepared the MNPs samples with matrices of poly(3,4-ethylenedioxythiophene) polystyrene sulfonate (PDOT:PSS) or H2O, and Co MNPs and carried out the magnetoresistive measurements. A switch-based model is used to understand the mechanism for the change in resistance. We further propose devices for memory based on MNPs. Building blocks for these devices are then fabricated using additive manufacturing techniques and measurements of change in resistance under the influence of a magnetic field are conducted. Niche applications of additive manufacturing techniques to the fabrication of these devices are proposed. The device uses MNPs suspended in a soft matter matrix. The application of a magnetic field is used to move the MNPs to or away from electrical contacts. Depending on the change of position of the MNPs, a connection is either made or broken, which can act as a 1 or a 0. The measured change in resistance observed in such devices is more than an order of magnitude depending on the matrix solution. The proposed device and its manufacturing process could be feasible for magnetic memory and in-memory computing devices on any flexible substrates. [ABSTRACT FROM AUTHOR]

Copyright of Al-Nahrain Journal for Engineering Sciences is the property of Republic of Iraq Ministry of Higher Education & Scientific Research (MOHESR) and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

A co‐continuous 50:50 blend of poly(lactic acid) (PLA) and poly(butylene adipate‐co‐terephthalate) (PBAT) was compounded with 10–40 wt% hemp hurd microparticles (<250 μm) to achieve balanced material properties for additive manufacturing (3D printing) applications. The blend and composites were further compatibilized with maleic anhydride via an in situ reactive extrusion process to enhance the adhesion between the polymers and the fillers and subsequently improve stress transfer between the components. All composite samples were processed further via injection molding and 3D printing processes to analyze and compare the rheology, morphology, thermal, mechanical properties, and other physio‐chemical properties. For the unfilled polymer blends, the injection molded and 3D printed sample specimens displayed similar mechanical properties. However, in the hemp filled composites, the injection molded specimens demonstrated enhanced mechanical properties. This indicates that the 3D printing process requires further parameter optimization to eliminate potential gaps between the printing layers and enhance mechanical properties. Overall, the PLA:PBAT blends filled with hemp hurd microparticles provided balanced composite properties in addition to their sustainability attribute, which makes them an appealing alternative for the fabrication of compostable and tough materials via additive manufacturing processes. Highlights: Upon maleation, the blend components formed a co‐continuous morphology.Sustainable plastic filament with up to 40 wt% hemp hurd micro particles.3D printing can compete with injection molding in filled composites.Successfully 3D printed model furniture with 30 wt% hemp filler. [ABSTRACT FROM AUTHOR]

Additive manufacturing transforms the industry by integrating innovative and intelligent technology, resulting in less material waste and faster prototyping. However, qualitative ambiguities are a significant barrier to digital fabrication methods to manufacture essential parts that require great precision and accuracy. However, qualitative ambiguities are a substantial barrier to digital fabrication methods to manufacture crucial parts that demand higher precision and accuracy. As a result, process monitoring techniques during production are becoming increasingly important. Acoustic emission testing is a prominent nondestructive testing approach that has demonstrated its capacity to detect and locate minute and internal developing cracks, allowing for real-time damage monitoring. This study briefly discussed different additive manufacturing processes, their influential parameters, and monitoring techniques, with particular emphasis on acoustic emission techniques. This study provides extensive recommendations for process monitoring of fused deposition modeling, powder bed fusion and directed energy deposition methods using acoustic emission testing. The different approaches used for handling the acoustic emission data and the effect of defects on acoustic emission signal parameters are also reviewed in this study. [ABSTRACT FROM AUTHOR]

Gas shielded welding is a widely applied fabrication processes in manufacturing industry. The present study will elucidate on an investigative approach to find the mechanical properties, influenced by several input parameters like welding current, voltage and wire spool speed in the Metal Active Gas Welding (MAG) of Mild Steel. Taguchi's L9 orthogonal array has been employed to analyse the process parameters. The levels of consequences of input parameters were investigated by applying analysis of variance (ANOVA). The microstructural orientations and mechanical properties of weld specimen are explored in this work. Welding current is an influential parameter to control tensile strength followed by welding voltage and federate of electrode. Furthermore, hardness of weld material has a greater effect of voltage including wire speed and current. [ABSTRACT FROM AUTHOR]

This work presents a comprehensive investigation into the optimization of critical process parameters associated with metal fused filament fabrication (Metal-FFF) for the production of copper-based components. The study focused on three different commercial and one self-manufactured filament, each with unique chemical compositions. These filaments were systematically optimized and the density was characterized for all processing steps, as well as the electrical conductivity on the specimen scale. Remarkably, two of the studied filaments exhibited exceptional properties after sintering with forming gas (up to 94% density and 55.75 M S / m electrical conductivity), approaching the properties measured for established manufacturing methods like metal injection molding. Finally, the research was extended to component-scale applications, demonstrating the successful fabrication of inductors with integrated cooling channels. These components exhibited water tightness and were used in induction hardening experiments, validating the practical utility of the optimized Metal-FFF process. In summary, the results show great promise in advancing the utilization of Metal-FFF in industrial contexts, particularly in the production of high-performance copper components. [ABSTRACT FROM AUTHOR]

Starting from the late 1980's, scanning probe microscopy has progressively diffused in Italy until today. In this paper, we provide a brief account of the main historical events and a current picture of the distribution of the active groups. A survey was prepared by LimeSurvey, made of six sections asking for personal and institutional data, human resources, equipment available, fields of interest, research projects, educational/dissemination activities, and two relevant publications in the last six years. It turns out that the Italian community includes more than seventy groups and two companies. It is widely diffused, although mostly concentrated near large academic and research institutions, often in locations where prominent Italian researchers have operated. This community is active in many scientific fields and can produce research of high international quality. It shows a wide competence, as proven by the list of research works published in journals ranked within the top 20% class. The diffusion of SPM microscopes in industry is still sporadic, possibly due to extensive collaborations between the research institutions and industries themselves. The authors hope that this work might be useful to the community and beyond, and that it might stimulate the formation of a more structured network. [ABSTRACT FROM AUTHOR]

Microfluidics, also known as lab-on-a-chip or micro total analysis systems, can precisely regulate and manipulate micro-sized fluids. They have great potential in biology, chemistry, and medicine, as well as other fields of science. By definition, microfluidic devices operate with small-volume samples and small reactant quantities, which renders them both efficient and affordable. However, such small objects have very demanding requirements for the utilized optical detection system. Due to the specifics of those devices, monitoring the results of experiments is carried out with commercial inverted optical microscopes. Unfortunately, that type of optical device is still expensive. In this article, we present a truly functional, inexpensive, standalone, three-dimensionally printed, and inverted microscope, including the design, engineering, and manufacturing process and some of the experiments that have been conducted with it. Finally, we summarize the advantages of this three-dimensionally printed microscope (including the total fabrication costs) and the future improvements that will be introduced to it. [ABSTRACT FROM AUTHOR]

Underground porous media are complex multiphase systems, where the behavior at the macro-scale is affected by physical phenomena occurring at the pore(micro)-scale. The understanding of pore-scale fluid flow, transport properties, and chemical reactions is fundamental to reducing the uncertainties associated with the dynamic behavior, volume capacity, and injection/withdrawal efficiency of reservoirs and groundwater systems. Lately, laboratory technologies were found to be growing along with new computational tools, for the analysis and characterization of porous media. In this context, a significant contribution is given by microfluidics, which provides synthetic tools, often referred to as micromodels or microfluidic devices, able to mimic porous media networks and offer direct visualization of fluid dynamics. This work aimed to provide a review of the design, materials, and fabrication techniques of 2D micromodels applied to the investigation of multiphase flow in underground porous media. The first part of the article describes the main aspects related to the geometrical characterization of the porous media that lead to the design of micromodels. Materials and fabrication processes to manufacture microfluidic devices are then described, and relevant applications in the field are presented. In conclusion, the strengths and limitations of this approach are discussed, and future perspectives are suggested. [ABSTRACT FROM AUTHOR]

Traditional methods of prosthesis fabrication are not efficient and user centric and are made for common purposes without focusing on individual demands of user which leads to rejection of prosthesis for long-term use. Utilizing advanced additive manufacturing techniques for fabrication of prosthesis makes the development process user centric and covers all the user demands thus providing better fit, comfort, and more stable gait rehabilitation for the user. The articles reporting fabrication of lower limb prosthesis and its socket are included in the study. Standard fabrication and additive manufacturing method are both systematically assessed by the reviewers. The review also covers the advanced methods of additive manufacturing that are presently being used for fabrication of rehabilitation devices. Additive manufacturing method of fabrication of prosthesis provides more flexibility for manufacturing prosthesis parts as per demand of the user. The fabrication method takes into account the residual limb and thus makes the prosthesis user-specific providing better comfort and fit. [ABSTRACT FROM AUTHOR]

The Architecture, Engineering and Construction sector requires an intense innovation process to reduce costs, intervention times, and improve energy performance. This is particularly true to increase the rate of deep renovations of the existing European building stock and therefore support the EU's 2050 decarbonisation targets. In this scenario, prefabrication can be considered a game-changer for the construction industry: on the one hand, it enables the adoption of an industrial mindset to the design, manufacturing, and installation of façade components, with the related advantages in terms of time, cost and quality; on the other, it allows for the customisation of components thanks to digital, BIM-based design and fabrication tools. However, its adoption in retrofit operations is still limited due, among other factors, to a lack of practical experience and a limited number of actual demonstration cases. This paper introduces an operative guideline to support a more widespread use of prefabricated thermal insulation components for the energy retrofit of existing buildings in the framework of a BIMenabled design and construction process. The guideline highlights the information flow and the role of each actor at every stage of the design and delivery process. The proposed guideline is finally tested through its application to a case study to show the feasibility of the process and the advantages deriving from the adoption of an industrialised approach to façade retrofit in terms of faster installation times. [ABSTRACT FROM AUTHOR]

Ti-6Al-3Nb-2Zr-1Mo (Ti6321) alloy, as a new type of marine metal, has excellent corrosion resistance and mechanical properties, but its application is restricted by the traditional manufacturing processes. Wire-arc directed energy deposition (DED) has some incomparable advantages in the efficient and customized fabrication of large/extra-large components, which makes it become a potential manufacturing process for the fabrication of Ti6321 alloy components. However, the formability and corresponding performance evaluation of wire-arc DEDed Ti6321 alloy remains unknown. Here, for the first time, the microstructure, mechanical properties and corrosion resistance of wire-arc DEDed Ti6321 alloy was characterized and compared with rolling, and the relationship between process-microstructure-properties was established. Results show that the full lamellar α+β structure of the DEDed specimens demonstrated better corrosion resistance than the near equiaxed α p + lamellar α s /β structure of rolled specimens. This is owed to the higher grain boundary density, more content of β phase and slighter element segregation of the DEDed specimens, resulting in a more uniform and stable passivation film on its surface. Meanwhile, the grain morphology and low dislocation density of the DEDed specimens causing in lower tensile strength (decrease by ∼15.6 %) but higher elongation (increase by ∼41.5 %) than the rolled specimens. Due to the presence of coarse prior-β grains, the DEDed specimens show expected anisotropy in building direction and traveling direction, but overall exhibits sufficient mechanical properties, which exceed the execution standard. This study verified the feasibility of fabricating Ti6321 alloy with idea properties by wire-arc DED, and provides a potential strategy for the production and practical application of large-size Ti6321 alloy components. [Display omitted] • The fabrication of Ti6321 alloy by wire-arc DED was conducted in-depth and systematic research for the first time. • Comparison between the mechanical properties and corrosion resistance of rolled and DEDed Ti6321 alloy was conducted. • Relationship between the process, microstructure and properties of DEDed Ti6321 alloy were studied. [ABSTRACT FROM AUTHOR]

In semiconductor manufacturing, virtual metrology (VM) is a method of predicting physical measurements of wafer qualities using in-process information from sensors on production equipment. The relevance vector machine (RVM) is a sparse Bayesian kernel machine that has been widely used for VM modeling in semiconductor manufacturing. Missing values from equipment sensors, however, preclude training an RVM model due to missing kernels from incomplete instances. Moreover, imputation for such kernels can lead to a loss of model sparsity. In this work, we propose a restricted RVM (RRVM) that selects its basis functions from only complete instances to handle incomplete data for VM. We conduct the experiments using toy data and real-life data from an etching process for wafer fabrication. The results indicate the model’s competitive prediction accuracy with massive missing data while maintaining model sparsity. Note to Practitioners—In recent decades, virtual metrology (VM) has focused on wafer fabrication in semiconductor manufacturing due to its advantages for process monitoring and automation. Typically, signals from production process equipment can predict wafer qualities in VM, which often leads to high data dimensionality. The relevance vector machine (RVM) is an algorithm that can provide a sparse solution to a Bayesian kernel method for a prediction model. Missing components in incomplete data due to sensor failures in wafer fabrication processes, however, hinder model training, and the existing approaches to handling missing data using imputation may lead to a loss of model sparsity. This article proposes a new method for RVM with incomplete data to train a model built on fully available instances by incorporating the available components of incomplete instances into model training. Using the proposed method, one can predict wafer qualities building a model trained to maintain its sparsity. Experiments indicate that the proposed model achieves competitive prediction performance and maintains model sparsity when incomplete instances are used. [ABSTRACT FROM AUTHOR]

Additive manufacturing technology has been evolving for several years. New material options, better processing speeds and greater autonomy are some of the characteristics of this technology that are still under research. However, in its current state, many commercially available 3D printers are competing with traditional manufacturing techniques in the fabrication of enduse products. In this paper, different additive manufacturing technologies are compared with injection moulding in a real-world case study. The comparison is conducted in terms of lead time and total production cost. From the case under study, it becomes obvious that none of the additive manufacturing technologies examined is yet able to practically replace injection moulding for medium- and high production volumes. However, when considering low-volume production, both rapid tooling and additive manufacturing may offer an alternative that could result into shorter lead times and decreased total production costs. In addition, the introduction of Additive Manufacturing in a producer's production portfolio can increase flexibility, reduce warehousing costs and assist the company towards the adoption of a mass customisation business strategy. [ABSTRACT FROM AUTHOR]

Fabrication spaces (Fab-spaces) provide individuals with access to numerous manufacturing equipment (including additive manufacturing), to carry out different types of projects. Although scholars are starting to speculate about the importance of these new organisational forms and their potential for future distributed innovation and production ecologies, this phenomenon is still largely unexplored. Building on existing multidisciplinary research, this paper offers the first empirical analysis of existing fab-spaces as providers of knowledge and production competencies. Amongst all the possible perspectives to derive a framework, we choose that of fab-space users who have an entrepreneurial intention. After deriving an analytical framework to position fab-spaces in the current academic discourse, the paper develops a classification, which considers the competences available to entrepreneurs, via fab-spaces, in conjunction with how these competences are provided. The resulting map reveals the complementarities amongst the different fab-spaces. It also shows that the current portfolio of fab-spaces supports mainly the distribution of innovation across locations and social groups. Several types of fab-spaces are currently well placed to support the transition from innovation to manufacturing, but their geographical distribution and range of manufacturing capabilities are not yet enough to provide a fully distributed manufacturing model. This study has practical consequences for entrepreneurs, in the better identification of the appropriate fab-spaces for their needs, and for policy-makers, to help position the different types of fab-spaces as elements for national systems of innovation and production. [ABSTRACT FROM PUBLISHER]

The selection of a scaffold-fabrication method becomes challenging due to the variety in manufacturing methods, biomaterials and technical requirements. The design and development of tissue engineering scaffolds depend upon the porosity, which provides interconnected pores, suitable mechanical strength, and the internal scaffold architecture. The technology of the additive manufacturing (AM) method via photo-polymerization 3D printing is reported to have the capability to fabricate high resolution and finely controlled dimensions of a scaffold. This technology is also easy to operate, low cost and enables fast printing, compared to traditional methods and other additive manufacturing techniques. This article aims to review the potential of the photo-polymerization 3D-printing technique in the fabrication of tissue engineering scaffolds. This review paper also highlights the comprehensive comparative study between photo-polymerization 3D printing with other scaffold fabrication techniques. Various parameter settings that influence mechanical properties, biocompatibility and porosity behavior are also discussed in detail. [ABSTRACT FROM AUTHOR]

For the prediction of residual distortions of high-performance steel alloy parts induced by laser melting deposition (LMD), two efficient simulation methods are developed, which are the improved thermal-mechanical coupled method and the multiscale method. In the improved thermal-mechanical coupled method, the detailed loading process of the moving laser heat source is omitted, and the deposited coarse blocks are used to divide the LMD parts, which can improve the efficiency of mechanism exploration for the LMD process. Based on the eight-layer line deposition model, the length range of the deposited coarse blocks that can improve the computational efficiency under the premise of accuracy is explored, which is 5–8 mm. The distortion of the substrate after printing two-layer multipath part by pragmatic deposition strategies is accurately predicted by this method, which is consistent with the experimental measurement. The deviation between the predicted maximum distortion and the actual value is only 0.8%. Furthermore, a multiscale method based on the inherent strain method is also adopted. The two simulation methods are used to predict the distortion of the substrate after depositing pragmatic square frame structure. The deviations of the maximum distortion predicted by the improved thermal-mechanical coupled method and the multiscale method are 5.2% and 4.3%, respectively. The time-consuming of the multiscale method is only 2.8% of the former. For the direct prediction of distortion results of large-sized LMD parts in engineering, the advantages of the multiscale method are significant. [ABSTRACT FROM AUTHOR]

In this paper, the design and manufacturing process of axial flux permanent magnet (AFPM) generators using rectangular neodymium ferrite boron (NdFeB) magnets are described to reduce magnet costs. Experimental studies are carried out by measuring the output voltage based on the design that has been made. The process of making a generator is made by varying the magnetic bars parallel and layered. Emphasis is placed on using commercially available rectangular magnetic teeth with simple techniques to achieve lower costs, while the fabrication steps in the manufacturing process are described in more detail. The design and prototype of the built AFPM generator are laboratories tested. The experimental study results obtained by the number of stator windings as many as 324 turns with an arrangement of 4 rectangular magnetic layers obtained an output voltage of 13.1 Volt at 1400 rpm. In addition, the structure of the generator design is simple and easy to manufacture and is suitable for rural applications for small-scale energy turbine applications. [ABSTRACT FROM AUTHOR]

In this paper, the dynamic and aeroelastic analysis of variable fiber spacing composite (VFSC) laminated plates are carried out. The effects and benefits of changing the fiber distribution pattern on natural frequency and mode shape are explored taking various boundary conditions. Taking cantilever boundary condition flutter characteristics of VFSC plate with different fiber distribution patterns are compared. Further stochasticity of flutter velocity due to randomness in material properties that could arise due to complex manufacturing and fabrication process of VFSC laminates is investigated. The perturbation technique is implemented to perform the stochastic as well as reliability analysis. Various parametric studies are conducted to check the accuracy and efficiency of perturbation technique, by comparing the results with that of Monte Carlo simulation and the first-order reliability method. [ABSTRACT FROM AUTHOR]

This paper introduces a batch fabrication method to manufacture Micro-Electro-Mechanical System (MEMS) platforms for 3D integration of sensors spatially-distributed on a 2D plane. In the heart of the concept is a foldable MEMS structure with polymer hinges which is used to support and guide the assembly of the discrete planar sensors by means of folding them into a 3D shape, like origami, providing controlled distribution of sensors in space. Flexible hinges carrying the electrical interconnects are a critical structural element of the platform and material selection study for those is the main focus of this paper. We analyzed different materials for flexible hinges fabrication, including photo-definable polyimide and parylene-C. Three approaches for sensor integration are presented: 1) co-fabrication; 2) sensor drop-in; and 3) transfer bonding. The prototypes of structures with different flexible hinge materials were fabricated and evaluated based on their mechanical flexibility, chemical compatibility, and material outgassing. Parylene-C exhibited similar or better performances compared to polyimide, demonstrating in each of the experiments a higher degree of thermal flexibility up to 350 °C, a superior chemical resistance against hydrofluoric acid, and 2.9 times lower outgassing. [2020-0301] [ABSTRACT FROM AUTHOR]

Wafer fabrication is characterised with advanced equipment, complex processes and high cost. Good production output, measured by yield given total throughput, should rapidly increase while considering the associated cost. Yield improvement models based on inspection usually consider the effect of excursion monitoring, while this work considers the effect of learning from experience as well. It assumes a production model where each machine’s output is inspected via wafers it processes, triggering repair if required. The yield improvement is modelled as a function of machine’s quality performance, accumulated inspections, inspection capacity and inspection rate. It exhibits a sigmoid shape curve with slow rise in startup, acceleration in ramp and almost a plateau in high volume manufacturing. Higher inspection rate enables more inspections over time, faster learning and higher yield. Yet, higher inspection rate at constant capacity prolongs the response time and can further drive lower yield. Clearly, higher inspection capacity enables faster yield improvement, but also increases equipment and operations costs. The cost analysis developed here illustrates the preferred inspection capacity and inspection rate, for minimising the overall cost combined of yield loss and inspection cost. It also shows preference to error with higher, rather than with lower, inspection capacity. [ABSTRACT FROM AUTHOR]

Additive manufacturing of complex porous polymer geometries is a new field of advanced materials processing. Such new geometries can be used to fabricate porous polymer monoliths serving as a support for other material functions. Here, a novel fabrication technology to manufacture tailored 3D porous monoliths via additive manufacturing and templating is presented. The method is based on replicating a 3D‐printed mold with a polymer solution of polyvinylidenfluorid‐triethyl phosphate (PVDF‐TEP) and induce phase separation of the polymer solution subsequently. In a second step, the mold is removed without affecting the porous PVDF phase. As a result, porous monoliths with a templated 3D architecture are successfully fabricated. The manufacturing process is successfully applied to complex structures and can be applied to any conceivable geometry. Coating the porous 3D monoliths with another PVDF solution allows applying a skin layer yielding an asymmetric membrane monolith. As a showcase, a polydimethylsiloxane coating even leads to a smooth and dense layer of micrometer size. The methodology enables a new generation of complex porous polymer monoliths with tailored surface coatings. For the combination of poly(dimethylsiloxane) on a porous support, gas/liquid mass transfer is used in blood oxygenation with reduced diffusion limitation is within reach. [ABSTRACT FROM AUTHOR]

In this article, a millimeter-wave (mmWave) chipless radio-frequency identification (RFID) tag is developed to operate in the $V$ -band for authentication applications. A novel approach based on tag backscattered E-field measurements at different orientation angles for unitary classification is proposed. The concept is based on the hardness to identically reproduce materials due to the inherent randomness in the fabrication process. These uncertainties are transcribed in very small variations that can be observed in the tag electromagnetic response. A set of 16 identical tags were fabricated, and each tag shares the same fabrication mask and manufacturing process method. Spatial diversity using the tag backscattering pattern (at two different angles) adds independent characteristics for estimating authenticity of each tag. To better exploit the large amount of data collected with this approach, a machine learning (ML) sighting classification is used, which enhances the system performance. The probability of error (PE) achieved with the method is around 1%. This PE is four times lower than the one obtained with a similar approach implemented in the $X$ -band. [ABSTRACT FROM AUTHOR]

The design rules for cylindrical shells subjected to uniform external pressure can be found in corresponding codes and recommendations, e.g. in EN 1993‐1‐6 (2007) or European Recommendation ECCS EDR5 (2008). Although the buckling strength of thin‐walled shells is highly dependent on the imperfections caused by various fabrication or manufacturing processes, the sensitivity of the buckling resistance of an imperfect shell to the amplitude of the geometric imperfections is not taken into account in design rules of standards. This paper investigates in detail the effect of boundary conditions and cylinder length on the linear buckling behaviour of cylindrical shells subjected to uniform external pressure. Following this, a comprehensive computational study is performed using geometrically nonlinear analyses on imperfect cylindrical shells with two‐imperfection types: (i) eigenmode‐affine form and (ii) longitudinal eigenmode‐affine pattern. Based on the numerical results obtained from eigenvalue analyses, the existing formulae of EN 1993‐1‐6 for the external pressure buckling factor Cβs of short cylindrical shells are modified to provide a more accurate prediction of the elastic critical circumferential buckling stress. The effects of geometric nonlinearity and imperfection sensitivity on the buckling strength are also briefly explored. [ABSTRACT FROM AUTHOR]

A hybrid manufacturing process for the fabrication of architected metal-ceramic and metal-metal interpenetrating phase composites (IPCs) is elaborated and employed to assess the mechanical performance of novel, advanced composite materials. In particular, aluminum-based co-continuous composites, reinforced with triply periodic minimal surface (TPMS) steel and ceramic (zirconia) phases are engineered, combining 3D-printing and investment casting techniques. The hybrid process results in excellent wettability between the ceramic-Al and steel-Al phases, characterized through Scanning Electron Microscopy (SEM) and micro-CT scanning analysis. The arising IPCs yield mechanical properties that utterly differ from the performance of the base ceramic or steel TPMS reinforcement topologies, with the ceramic-Al composites to furnish a highly ductile response and steel-Al IPCs a remarkable post-elastic stiffening performance. Ceramic-based IPCs yield a specific energy absorption (SEA) that is more than 400 times higher than the one of single-phase ceramic metamaterials, while steel-based IPCs allow for SEA values in the order of 50 J/g, values which rank among the highest ever reported for architected IPCs. A broader Ashby-type classification is provided, while the efficiency of the IPC plastification process is associated with the obtained SEA values. Moreover, experimental results are complemented by finite element analysis insights in the effect of the interpenetrating phase design on the inner stresses developed. The hybrid manufacturing process and the co-continuous composites investigated open novel pathways in the engineering of next-generation multifunctional architected IPCs for base material combinations beyond the ones here considered. [Display omitted] • A hybrid-casting, interpenetrating phase composites manufacturing method is elaborated. • Novel, TPMS-based, ceramic-aluminum and steel-aluminum IPCs are engineered. • Their inner co-continuous composition and mechanical performance are assessed. • A novel effective material performance space is revealed and comparatively classified. • Exceptional specific energy absorptions and crushing force efficiencies are reported. [ABSTRACT FROM AUTHOR]

This study proposes using double-layer wire-grid structures to create narrow-band, perfect plasmonic absorbers, which depend on polarization, for the short-wavelength visible and near-ultraviolet regions of the electromagnetic spectrum. A rigorous coupled-wave analysis reveals that the maximum absorption attained using Ag and Al is ~ 90% at 450 and 375 nm. Experiments using Ag yielded results similar to those predicted by simulations. These results demonstrate that narrow-band perfect plasmonic absorbers, which depend on the polarization, can be realized at 450 and 375 nm using Ag or Al. [ABSTRACT FROM AUTHOR]

The Energy, Environment, Science and Technology (EES&T) Directorate of the Idaho National Laboratory (INL) launched an advanced manufacturing platform in 2015, which has evolved into a national laboratory initiative across all INL directorates as of 2018. Thus, all three INL Directorates, including nuclear and cyber security, are engaged in a unified advanced manufacturing strategy. The ultimate goal of this initiative is to increase the economic competitiveness of energy-generation systems, security systems, structural components, and industrial chemical processes by advancing the knowledge that supports improved fabrication and manufacturing technologies. To move this innovation forward, INL is designing, building and testing what is not possible with traditional manufacturing techniques. The development of advanced manufacturing technologies has the potential to significantly expand the design options of the solutions to manufacturing problems that have been challenging the industrial sector for years. • This article will describe the focus areas that INL has decided to address in the industrial chemical processes thrust. In this regards, high energy-consuming and low energy-efficient processes are of our top concerns. The manufacturing of olefins from natural gas components namely methane and ethane presents these challenges and give us the opportunity to address it as a first priority in the INL's recently established advanced manufacturing initiative. • One may envision the conversion of alkanes to alkenes as the first step of functionalization, i.e. creating unsaturation sites that convert low reactive alkanes into more reactive building units. • This new vision of Lego-like chemical manufacturing is a paradigm shift from the historical chemical manufacturing approach of starting from heavy crude and cracking down to smaller hydrocarbon building blocks. INL's new chemical manufacturing approach leads to significant energy saving and reduction of waste products. [ABSTRACT FROM AUTHOR]

This paper presents an integrated release and dispatch policy for semiconductor wafer fabrication. In this policy, the concept of virtual production lines (VPLs) is first introduced to allocate production time for each process step, and the average queuing time information is derived from the target WIP distribution which is obtained by simulations. Then, a pull VPLs-based effective-workload control (EWL-n-Ctrl) policy is proposed to control the release process, and a queuing time ratio (QTR) rule is put forward to control the dispatch process. The behaviour of EWL-n-Ctrl is analysed using the Mini-Fab model. Results of the numerical experiments show that the integrated release and dispatch policy (EWL-n-Ctrl+QTR) outperforms common rule-based scheduling policies in terms of the average cycle time, the standard deviation of the cycle time and the work in process under a prescribed throughput level. A simulation study into the effect of capacity utilisation levels and product mix ratios is also carried out. [ABSTRACT FROM AUTHOR]

Purpose: This article explores a particular on-demand fabrication unit, the microfactory (MF). It identifies and contrasts several MFs and proposes a taxonomy. This research also explores online manufacturing platforms (OMP) that complement certain MFs. Design/methodology/approach: This research implements a multiple case study (71 cases in 21 countries), triangulating data available on the web with interviews, virtual/physical tours and experiential research. Findings: The results suggest that automation and openness are the main dimensions that differentiate the MFs. Using these dimensions, a taxonomy of MFs is created. MFs with relatively low automation and high openness tend to be innovation-driven microfactories (IDMFs). MFs with high automation and low openness levels tend to be customization-driven microfactories (CDMFs). And MFs with relatively low automation and low openness tend to be classic machine shops (MSs). There are two types of OMP: closed (COMPs) and multisided (MOMPs). MOMPs can be low-end or high-end. Practical implications: In a world where online platforms are becoming central to the reinvention of manufacturing, multisided online platforms and small fabricators will become strongly symbiotic. Originality/value: This paper offers a clearer conceptualization of MFs and OMPs, which may help to better understand the reality of local on-demand fabrication. Moreover, it explores a new type of experiential research, which tries to describe and interpret firms through transactional activities. Many details of a firm that are difficult to capture via interviews and netnography can be revealed this way. [ABSTRACT FROM AUTHOR]

Aircraft's constant operation in tough conditions necessitates the need for structural components of high strength yet low weight. Composite materials are being used as an alternative to conventional aluminum alloys because of their competitive strength-to-weight and stiffness-to-weight ratios. In this paper, the detailed design procedure of a light-aircraft composite material fuselage tooling in three dimensions is shown. In its operation, the layup tools provide a surface for the composite part which is the correct shape of the part and is stable through the cure cycle, and also providing a means of indexing the part for the next manufacturing operation. This aims to achieve the desired position accuracy and improve the efficiency of assembly procedures. All the parts are designed and measured using CATIA Version 5 software. The fuselage modeled here is a section of Beechcraft King Air 250. At the time of writing, the manufacturing process for the fabrication of this fuselage is entirely different. This design should be viewed as an alternative process as it would cut down weight and costs while improving safety. [ABSTRACT FROM AUTHOR]

This study fabricates a roughing electrode of electrical discharge machining (EDM) using a rapid prototyping (RP) system and investment casting technology, which reduces the overall time that is required for fabrication and the cost of the manufacturing process for a selected electrode. Pro/E (3D CAD) software is used to design the electrode prototype, which has a complex appearance, and to transform the CAD model into stereolithography (STL) format. An RP machine (Zcorp 402 3DP) is used to construct a gypsum-based powder model. After a sealing process using the permeation of resin, the water resistance and strength of the gypsum-based material are increased. The manufacturing process then involves creating a wax model with a gypsum electrode that is strengthened by resin permeation by casting a vulcanized silicone molding. The brass electrode is fabricated using investment casting technology. The results of an EDM test show that the brass electrodes with RP that are manufactured perform well and the total time that is required to machine the EDM electrode using RP is 15.8% less than the time that is required for a CNC machining process. [ABSTRACT FROM AUTHOR]

This research has successfully introduced a novel fabrication process to manufacture aluminium alloy (AA)7150-X wt.% silicon carbide (SiC) (X = 0.5, 1.0, 1.5, and 2.0) nanocomposites. The effect of silicon carbide nanoparticle content on microstructure, density, microhardness, porosity and ultimate tensile strength was studied. An optical microscope was used to find the grain formation while electron microscopy was used for ceramic nanoparticle distribution studies and fractographic studies of fracture surface. Energy Dispersive X-Ray Spectroscopy and X-ray diffraction were used to study the chemical composition of various composites and SiC particles. Significant enhancement was observed in mechanical properties at as-cast state of composites. Nevertheless, AA7150–1.5%SiC nanocomposite exhibited 83.47% reduction in porosity, 23.9% enhancement in microhardness, 60.1% in ultimate tensile strength compared to base alloy. [ABSTRACT FROM AUTHOR]

The Life of Type (LOT) of a naval High Speed Light Craft (HSLC) can be limited by its structural fatigue life. The fatigue life of a ship is influenced by many factors, such as geometry, fabrication quality, the long-term load distribution, and analytical techniques. The complex dependencies between these factors and die fatigue life cause uncertainty in predictions. A lack of understanding of uncertainty can adversely affect the management of LOT risks, resulting hi the reduction of availability of the ship and costly repairs. Therefore, improved understanding of the benefits and limitations of different fatigue life evaluation approaches informs the management of risks relating to the ship's LOT. This paper presents the fust phase of work in a comparative analysis of different fatigue life evaluation approaches for naval HSLC. The present work involves a holistic data review, codification of tlie data to reveal key themes, and individual expert comparative analysis of the different approaches. The next phase of the study is also described. [ABSTRACT FROM AUTHOR]

Endoglucanase (endocellulase, EC 3.2.1.4) is one of the most widely used enzymes in industry. Despite its importance, improved methods for the rapid, selective, quantitative assay of this enzyme have been slow to emerge. In this work, we have designed an aptasensor platform for ultrasensitive endoglucanase II detection based on DNA aptamer and reduced graphene oxide/Au nanoparticles (RGO/AuNPs). The surface morphology of RGO/AuNPs was characterized by various techniques such as transmission electron microscopy (TEM), X-ray diffraction (XRD), energy-dispersive X-ray spectroscopy (EDX) methods. The aptasensor characterization was monitored with electrochemical techniques. Using RGO/AuNPs as a nanomaterial can effectively increase the conductivity of biosensor electrode. Moreover, using an RGO/AuNPs/aptamer platform in the presence of endoglucanase, the sensor system is able to generate a signal, which significantly improves the selectivity of the aptasensor. The fabricated aptasensor exhibits high sensitivity and selectivity to endoglucanase II with a low limit of detection (LOD) ˂0.1 nM. Unlabelled Image • Selective detection of low concentrations of specific biomolecules is important in industrial processes. • Endoglucanase (endocellulase, EC 3.2.1.4) is one of the most widely used enzymes in industry. • An aptasensor platform based on DNA aptamer and reduced graphene oxide/Au nanoparticles has been developed. • Developed aptasensor exhibits high sensitivity and selectivity with a low limit of detection (<0.1 nM) for endoglucanase. [ABSTRACT FROM AUTHOR]

The successful welding of a product or services not only depends on the manufacturing design or the fabrication technique. How the product is manufactured and how the quality control at each and every stage of operation will only enhance the standards of the Product. An attempt is made to inform the welding personal by adopting the systematic quality control system at every step of the manufacturing process consistently will increase product quality and reduce the cost of manufacturing. The controls to be adopted at various stages are being dealt in this Article. [ABSTRACT FROM AUTHOR]

The current capabilities and state of the art in fabricating continuous fiber reinforced thermoplastic (TP) matrix composite parts for aerospace structural applications are discussed. These materials and technologies are providing significant cost reduction compared to current state of the art thermoset materials and processes. The major reason for this due to the ability to process parts quickly as no reactive chemistry is required. Fabric reinforced TP composites have been used in aircraft production applications for many years, mostly in interior and secondary structure applications. Unidirectional tapes provide maximum design flexibility and structural performance, but the rapid fabrication of parts manufactured from unidirectional tapes have many challenges. These are now being overcome resulting in the use of TP composites in highly structural aerospace applications while achieving the fabrication cost benefits. [ABSTRACT FROM AUTHOR]