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Soft robots have been receiving unprecedented attention in recent years for being able to be used side-by-side with humans, exploring dangerous environments and confined spaces, moving across uneven terrain, and solving problems that rigid robots cannot solve. The wide range of additive manufacturing techniques has also boosted research in the area. This work summarizes the characteristics of the five most relevant techniques – FDM, DIW, SLS, Inkjet, and SLA – for fabricating soft robots together with case studies. A summary contains models of industrial-sized additive manufacturing machines that can compose a facility for fabricating large-scale soft robots.

Harmonic oscillators with multiple abrupt jumps in their frequencies have been investigated by several authors during the last decades. We investigate the dynamics of a quantum harmonic oscillator with initial frequency $\omega_0$, that undergoes a sudden jump to a frequency $\omega_1$ and, after a certain time interval, suddenly returns to its initial frequency. Using the Lewis-Riesenfeld method of dynamical invariants, we present expressions for the mean energy value, the mean number of excitations, and the transition probabilities, considering the initial state different from the fundamental. We show that the mean energy of the oscillator, after the jumps, is equal or greater than the one before the jumps, even when $\omega_1, Comment: 11 pages, 12 figures

The use of ultra-high-strength steels (UHSS) has been growing in recent years, mainly in the automotive industry. Since these steels have high strength and hardness, more applied stresses are required to deform them, probably also impacting friction behaviour. In this article, a variation in the process parameters commonly observed in sheet-metal forming, such as contact pressure, sliding speed, lubrication and working temperature was performed. The material used was TRIP1000. These process parameters were varied, aiming to investigate the friction-coefficient behaviour; however, it was observed that there were no significant variations, indicating that the steel hardness may have contributed to this. Another finding is that, even if the lubricant did not change the average value of the friction coefficient, it contributed to a more stable process, favouring the absence of premature wear of the tools.

The friction that occurs in forming processes plays a fundamental role in the industry as it can be responsible for both manufacturing failure and its success. Scientific research has been done to try to understand this phenomenon as well as simulation software has been implemented aiming to predict the tribological behavior of the metallic pair in contact. Thus, this chapter is dedicated to the analysis of the main parameters that can influence the coefficient of friction, especially for metal manufacturing processes. Some simulation models that try to predict the behavior of friction under certain conditions of process speed, contact pressure and operating temperature will also be presented.

Materials chemistry and physics 276, 125388 (2022). doi:10.1016/j.matchemphys.2021.125388, Microstructural and crystallographic aspects arising from thermomechanical processing of a Ti���6Al���4V alloy in ��and ��+�� phase fields were studied by electron backscatter diffraction and both conventional and high energysynchrotron X-ray diffraction. The impact of deformation in the single �� field on the final microstructure has beenacknowledged by an increase of the retained �� phase content and decrease of martensitic c/a ratio with thereduction of strain rate, although no significant influence of strain rate on the well-defined fiber texture of ����� hasbeen observed. During deformation in the ��+�� field, texture weakening has been observed, and misorientationangle/axis distribution analysis has evidenced randomization and loss of the Burgers orientation relationshipbetween �� and �� upon globularization. The behavior of deformed �� lamellae in the ��+�� field was also evaluatedin terms of internal misorientation spread and lattice rotation around the deformation axis, corroborating thatglobularization takes place through dynamic recrystallization, boundary splitting and shearing. Globularizedgrain size was shown to be exponentially proportional to strain rate decrease. Lower strain rates in the ��+�� fieldalso increase the �� phase fraction and decrease the c/a ratio of the �� phase, leading to values closer to the idealone for titanium. However, an excessive amount of �� causes its instability during quenching, resulting in itsdecomposition into secondary �� during cooling., Published by Elsevier, New York, NY [u.a.]

Purpose Information on the brain microstructure can be probed by Diffusion Magnetic Resonance Imaging (dMRI). Neurite Orientation Dispersion and Density Imaging with Diffusivities Assessment (NODDIDA) is one of the simplest microstructural model proposed. However, the estimation of the NODDIDA parameters from clinically plausible dMRI acquisition is ill‐posed, and different parameter sets can describe the same measurements equally well. A few approaches to resolve this problem focused on developing better optimization strategies for this non‐convex optimization. However, this fundamentally does not resolve ill‐posedness. This article introduces a Bayesian estimation framework, which is regularized through knowledge from an extensive dMRI measurement set on a population of healthy adults (henceforth population‐based prior). Methods We reformulate the problem as a Bayesian maximum a posteriori estimation, which includes as a special case previous approach using non‐informative uniform priors. A population‐based prior is estimated from 35 subjects of the MGH Adult Diffusion data (Human Connectome Project), acquired with an extensive acquisition protocol including high b‐values. The accuracy and robustness of different approaches with and without the population‐based prior is tested on subsets of the MGH dataset, and an independent dataset from a clinically comparable scanner, with only clinically plausible dMRI measurements. Results The population‐based prior produced substantially more accurate and robust parameter estimates, compared to the conventional uniform priors, for clinically feasible protocols, without introducing any evident bias. Conclusions The use of the proposed Bayesian population‐based prior can lead to clinically feasible and robust estimation of NODDIDA parameters without changing the acquisition protocol.

In the current world scenario, which is experiencing the arrival of new technologies, Industry 4.0, increased mobility and a pandemic environment, the achievement of sustainability demands proactive solutions. One of these actions includes the design of sustainable products. Several authors have studied the scientific discipline of Life Cycle Engineering (LCE), which encompasses environmental, social and economic dimensions. However, current LCE models have gaps, such as the need to incorporate a more holistic view, uncertainty and integrated analysis. In this context, the aim of this paper is to present a model to evaluate the technology sustainability (TS) dimension. The methodology of the present work involves a literature review, the development of a model with qualitative and quantitative data, and application in a case study. A structure was developed to include market, technical, and technology-scaling perspectives. The computational model uses hybrid Bayesian networks, based on probabilistic theory, and incorporates uncertainty using sustainability indicators. The model includes quantitative and qualitative variables derived from experts’ opinions. The results of applying the model to a real research project on manhole covers indicate that this analytical tool can support decision-making, allowing a new dimension to be incorporated into LCE analysis. Finally, the model allows LCE analysis to be applied in a variety of circumstances, such as strategy development or the selection of more sustainable products, as well as the evaluation of competing products.

Background\ud \ud Tissue microarrays (TMAs), where each block (and thus section) contains multiple tissue cores from multiple blocks potentially allow more efficient use of tissue, reagents and time in neuropathology.\ud \ud \ud \ud New Method\ud \ud The relationship between data from TMA cores and whole sections was investigated using ‘virtual’ TMA cores. This involved quantitative assessments of microglial pathology in white matter lesions and motor neuron disease, alongside qualitative TDP-43 inclusion status in motor neuron disease cases. Following this, a protocol was developed for TMA construction.\ud \ud \ud \ud Results\ud \ud For microglial pathology we found good concordance between virtual cores and whole sections for volume density using one 1.75 mm core (equivalent to a 2 mm core after accounting for peripheral tissue loss). More sophisticated microglial cell size and measures required two cores. Qualitative results of pTDP-43 pathology showed use of one 1.75 mm core gave a 100% sensitivity and specificity within grey matter, and 88.3% sensitivity and 100% specificity within white matter. A method of producing the TMAs was suitable for immunohistochemistry both manually and by autostainer, with the minimal core loss from the microscope slide.\ud \ud \ud \ud Comparison with Existing Methods\ud \ud TMAs have been used infrequently in post mortem neuropathology research. However, we believe TMAs give comparable tissue assessment results and can be constructed, sectioned and stained with relative ease.\ud \ud \ud \ud Conclusions\ud \ud We found TMAs could be used to assess both quantitative (microglial pathology) and qualitative pathology (TDP-43 proteinopathy) with greatly reduced quantities of tissue, time and reagents. These could be used for further work to improve data acquisition efficiency.

Aiming to decrease friction coefficient () during the forming of magnesium alloy sheets, nine (9) tools with different hole geometries in their surface (flat, elliptical, and circular) were manufactured from steel Boehler W400 VMR (as known as DIN 1.2343).. Tribological investigations were accomplished on a strip drawing machine at 288 &deg, C without lubricants. When compared with a standard tool (surface flat), on average, tools with circular geometries in their surface showed the smallest friction coefficient, while tools with elliptical geometries shown higher. The friction coefficient also was confronted with the ratio between area occupied by holes in the surface of the tool and the total tool surface (i.e., factor f (%)), hole diameter (&Oslash, ), and the distance between circle centers (d(c,c)). Principal Component Analysis (PCA) complemented the experimental approach. In summary, both approaches (experimental and theoretical) indicated that the manufactured tool with circular geometries on its surface presented lower friction coefficient values on the forming processes of the magnesium AZ31 sheets.

Materials characterization 165(110400), 1-10 (2020). doi:10.1016/j.matchar.2020.110400, The aging behavior of a Ti-6Al-4V alloy with different starting microstructures was evaluated by means ofsynchrotron X-ray diffraction, scanning-transmission electron microscopy and micro-hardness measurements.Initial microstructures were produced by thermal and thermomechanical treatments and comprised differentmorphologies of �� phase (martensitic, lamellar, bimodal and globular), as well as the presence or absence of the�� phase. Results show that one or more of the following phenomena can take place during aging and contributeto the hardening of the alloy: �� decomposition into fine secondary �� laths; transformation of the metastablemartensitic ����� into the equilibrium �� phase; and precipitation of the intermetallic Ti$_3$Al. The composition anddistribution of the �� phase was shown to affect the precipitation of secondary �� during aging, while the compositionof the �� phase plays a key role on the formation of Ti$_3$Al. In situ X-ray diffraction studies of the earlystages of aging show the kinetics of the ���������� conversion by the reduction in FWHM of XRD reflections, indicatethe contribution to hardening by the increase of the c/a ratio and the consequent limitation of active slip systemsand depict the chemical homogenization and decomposition of the �� phase., Published by Science Direct, New York, NY

The impact of starting microstructure on the isothermal behavior of β-metastable Ti–5Al–5Mo–5V–3Cr alloy during aging at 400 °C for 8 h was studied by means of in situ synchrotron X-ray diffraction. Results show that prior deformation does not accelerate phase precipitation during heating, but has an influence on secondary α precipitation during aging, and that the composition of the β matrix, which is affected by the amount of primary α formed depending on the preliminary processing route applied, plays a major role. At this aging temperature, α" phase tends to form from the β matrix in high quantities without the presence of primary α phase or with a low fraction of this phase, and the conversion of α" into α is sluggish, being faster in the β-heat-treated condition, whereas a continuous β → α transformation occurs, with no reliable evidence of α" precipitation, in the α+β-heat-treated condition. Isothermal precipitation was enough to promote a significant hardness increase in the alloy. Observation of the behavior of α" based on its atomic y-coordinate and orthorhombicity helped to elucidate its transformation pathway.

The friction that occurs in forming processes plays a fundamental role in the industry as it can be responsible for both manufacturing failure and its success. Scientific research has been done to try to understand this phenomenon as well as simulation software has been implemented aiming to predict the tribological behavior of the metallic pair in contact. Thus, this chapter is dedicated to the analysis of the main parameters that can influence the coefficient of friction, especially for metal manufacturing processes. Some simulation models that try to predict the behavior of friction under certain conditions of process speed, contact pressure and operating temperature will also be presented.

Due to their applicability for manufacturing dense, hard and stable coatings, Physical Vapor Deposition (PVD) techniques, such as High Power Impulse Magnetron Sputtering (HiPIMS), are currently used to deposit transition metal nitrides for tribological applications. Cr-Al-N is one of the most promising ceramic coating systems owing to its remarkable mechanical and tribological properties along with excellent corrosion resistance and high-temperature stability. This work explores the possibility of further improving Cr-Al-N coatings by modulation of its microstructure. Multilayer-like Cr1−xAlxN single films were manufactured using the angular oscillation of the substrate surface during HiPIMS. The sputtering process was accomplished using pulse frequencies ranging from 200 to 500 Hz and the resulting films were evaluated with respect to their hardness, Young’s modulus, residual stresses, deposition rate, crystallite size, crystallographic texture, coating morphology, chemical composition, and surface roughness. The multilayer-like structure, with periodicities ranging from 250 to 550 nm, were found associated with misorientation gradients and small-angle grain boundaries along the columnar grains, rather than mesoscopic chemical modulation of the microstructure. This minute modification of microstructure along with associated compressive residual stresses are concluded to explain the increased hardness ranging from 25 to 30 GPa, which is at least 20% over that expected for a film of the same chemical composition grown by a conventional PVD processing route.

The performance of perovskite films in capacitor devices is strongly determined by the level of residual stresses developed after their fabrication at high temperatures. Quantification of these stresses by X-ray diffraction is not straightforward in perovskite films due to the complexity of the crystalline structure and a lack of effective elastic diffraction constants. In this work we apply a simple and accurate method to estimate the residual stresses developed in Pb(Nb,Zr,Ti)O3 perovskite films grown by metal–organic chemical vapor deposition on the Pt electrode. The stress was directly measured in the Pt bottom electrode film before and after the deposition of the perovskite film and compared with intrinsic and thermal stresses calculations. Our results reveal in-plane tensile stresses of 676(8) MPa developed in the Pt electrode, which mainly originate from the relative thermal contraction between Pb(Nb,Zr,Ti)O3 and Pt as well as the cubic-tetragonal perovskite phase transformation after deposition. This methodology is straightforward and highlights the possibility to perform systematic studying for tailoring stress conditions and improving the performance of perovskite films for capacitor applications.

The SARS-CoV-2 pandemic in Brazil has grown rapidly since the first case was reported on 26 February 2020. As the pandemic has spread, the low availability of medical equipment has increased, especially mechanical ventilators. The Brazilian Unified Health System (SUS) claimed to have only 40,508 mechanical ventilators, which would be insufficient to support the Brazilian population at the pandemic peak. This lack of ventilators, especially in public hospitals, required quick, assertive, and effective actions to minimize the health crisis. This work provides an overview of the rapid deployment of a network for maintaining disused mechanical ventilators in public and private healthcare units in some regions of Brazil during the SARS-CoV-2 pandemic. Data referring to the processes of maintaining equipment, acquiring parts, and conducting national and international training were collected and analyzed. In total, 4047 ventilators were received by the maintenance sites, and 2516 ventilators were successfully repaired and returned to the healthcare units, which represents a success rate of 62.17%. The results show that the maintenance initiative directly impacted the availability and reliability of the equipment, allowing access to ventilators in the public and private health system and increasing the capacity of beds during the pandemic.

The modified ASTM A297 Gr. HH austenitic stainless steels are a group of refractory alloys designed for high temperature applications that required elevated mechanical strength, such as those found in petrochemical furnace structures and in the steel industry. This study examines the overall microstructural features and cyclic oxidation behaviour of modified HH steels with 0.09%Nb and 0.77%Nb additions. The investigations involved thermodynamic simulations and microstructure analyses conducted by optical and scanning electron microscopy of the substrate materials in the as-cast and aged conditions. The cyclic oxidation tests were performed at 900 °C in atmospheric conditions with oxidation times up to 960h. The resulting oxide scales were analyzed by X-ray diffraction and scanning electron microscopy. The thermodynamic simulations and microstructure analyses of the as-cast steels revealed larger amounts of niobium carbides in the 0.77%Nb steel than in the 0.09%Nb steel, in connection with larger amounts of chromium in solution. Despite this precipitation difference, no significant changes were noticed in the long-term oxidation behaviour of the tested materials.

In friction surfacing (FS), material is deposited onto a substrate in the plasticized state, using frictional heat and shear stresses. The coating material remains in the solid state and undergoes severe plastic deformation (SPD) at high process temperatures (≈0.8 Tmelt), followed by high cooling rates in the range of 30 K/s. Dynamic recrystallization and the thermal cycle determine the resulting microstructure. In this study, Ni-based alloy 625 was deposited onto 42CrMo4 substrate, suitable, for instance, for repair welding of corrosion protection layers. Alloy 625 is known to undergo discontinuous dynamic recrystallization under SPD, and the resulting grain size depends on the strain rate. The coating microstructure was studied by microscopy and electron backscatter diffraction (EBSD). The coatings exhibit a fully recrystallized microstructure with equiaxed grains (0.5–12 µm) and a low degree of grain average misorientation. Flow lines caused by a localized decrease in grain size and linear alig...

Structural adhesives methods for joining multi material sheets have been focus of studies and researches for the last years. The most common and widely known type of test is the tensile test of single lap joints (SLJ). However, there are opportunities for analyzing the mechanical performance of such method in SLJ with materials of different properties, such as ductile structural aluminum alloys and high strength steels. It’s also known that the stress state of SLJ, when stressed longitudinally, generates secondary forces. One of them is known as cleavage force which initially leads to the failure of bonded joints. The aim of this work is to analyze the stress state of similar and dissimilar materials SLJ submitted to tensile stresses and also the influence of some variables, such as overlap length, adhesive film thickness and adherend yield limit, over the stress strength of the samples. As adherend materials it was selected the structural aluminum alloy AA 5083 H111 and the high strength steel DP600. At the end of this work it is expected to understand the proper stress state of the SLJ when using similar and dissimilar materials, identifying stress concentrators that bring the structure to fail, using the Digital Image Correlation (DIC) method. It was discovered that the yield strength associated with the overlap length highly influences the SLJ strength, by leading it to a close to pure adhesive shear stress state.

The conventional sheet metal forming processes, such as deep drawing and stretch forming, are used to produce large batches of parts, however they incur in higher initial manufacturing costs attributed to the use of a large amount of tooling. The application of conventional and incremental forming processes combined in the same metal sheet is called hybrid forming. This hybrid process is enacted by pre-forming the sheet through the stretch forming process followed by the final manufacture using the incremental process. The objective of this work is to analyze the influence of the pre-strain imposed during the conventional process on the DC04 steel relative to the maximum strain obtained. A numerical simulation was used to define the parameters for the conventional process and to evaluate the experimental results. The higher major true strains are inversely proportional to the pre-strain in both experimental and simulated results.

This immunohistochemistry dataset contains the main structures in deep subcortical white matter (axons, astrocytes, and myelinated axons) in a representative cohort of an ageing population. A set of samples from 90 subjects of the Cognitive Function and Ageing Study (CFAS) were analysed, stratified into three groups of 30 subjects each, in relation to the presence of age-associated deep subcortical lesions. High-resolution microscopy data enables the extraction of valuable information, such as volume fractions, for the construction and validation of diffusion MRI (dMRI) models. The dataset provided here was used in Coelho et al. [1].

Austempered ductile irons exhibit an interesting combination of properties such as low cost, elevated strength, fatigue and wear resistance. In the present contribution, the influence of shot-peening on the dry-sliding wear behavior of as-cast and austempered ductile irons was evaluated. Specimens from a casting with an initial ferritic-pearlitic matrix were submitted to austempering at 320 °C for 60 min after which an ausferritic microstructure with 40 HRC and approximately 30% retained austenite was obtained. The wear and friction behaviors were assessed by applying ball-on-disc tests using a hard metal (WC) counter-body on as-cast and austempered materials before and after shot-peening and after removal of the rough surface layer created by the shot-peening process. The microstructure of the tested materials was evaluated by X-ray diffraction, optical and scanning electron microscopy. After shot-peening, the austempered samples experienced an elevated increase in surface hardness because of the formation of strain-induced martensite, but a reduction in wear resistance caused by the increase in surface roughness. By removing 20 μm from the surface of the shot-peened samples, it was possible to reduce roughness while preserving the hardened layer, which was found to improve wear resistance.

This study aims to statistically describe histologically stained white matter brain sections to subsequently inform and validate diffusion MRI techniques. For the first time, we characterise volume fraction distributions of three of the main structures in deep subcortical white matter (axons, astrocytes, and myelinated axons) in a representative cohort of an ageing population for which well-characterized neuropathology data is available. We analysed a set of samples from 90 subjects of the Cognitive Function and Ageing Study (CFAS), stratified into three groups of 30 subjects each, in relation to the presence of age-associated deep subcortical lesions. This provides volume fraction distributions in different scenarios relevant to brain diffusion MRI in dementia. We also assess statistically significant differences found between these groups. In agreement with previous literature, our results indicate that white matter lesions are related with a decrease in the myelinated axons fraction and an increase in astrocytic fraction, while no statistically significant changes occur in axonal mean fraction. In addition, we introduced a framework to quantify volume fraction distributions from 2D immunohistochemistry images, which is validated against in silico simulations. Since a trade-off between precision and resolution emerged, we also performed an assessment of the optimal scale for computing such distributions.

Phase transformations in a lamellar Ti–5Al–5Mo–5V–3Cr–1Zr (Ti-55531) alloy upon heating at continuous rates of 5, 20 and 100 °C/min has been studied by in situ high energy X-ray diffraction (HEXRD), aided by scanning and transmission electron microscopy, atom probe tomography and hardness measurements. During slow heating, the β phase has shown a behavior suggestive of additional transformations other than the continuous α → β decomposition observed at higher heating rates. Such behavior has been attributed to the precipitation of an embryonic isothermal ω phase. APT analyses have shown that no elemental partitioning occurs between the β matrix and the lamellar α phase, but it does between β and grain boundary α, suggesting that ω phase precipitates with solute rejection in regions outside lamellar colonies embedded in an enriched matrix. Above 500 °C, diffusion becomes significantly enhanced and α decomposition takes place.