Strong Partitioning Research Articles

Scanning electron microscopy and atom probe tomography characterization of laser powder bed fusion precipitation strengthening nickel-based superalloy

Atom probe tomography (APT) was utilized to supplement scanning electron microscopy (SEM) characterization of a precipitation strengthening nickel-based superalloy, Alloy 247LC, processed by laser powder bed fusion (L-PBF). It was observed that the material in the as-built condition had a relatively high strength. Using both SEM and APT, it was concluded that the high strength was not attributed to the typical precipitation strengthening effect of γ’. In the absence of γ’ it could be reasonably inferred that the numerous black dots observed in the cells/grains with SEM were dislocations and as such should be contributing significantly to the strengthening. Thus, the current investigation demonstrated that relatively high strengthening can be attained in L-PBF even in the absence of precipitated γ’. Even though γ’ was not precipitated, the APT analysis displayed a nanometer scale partitioning of Cr that could be contributing to the strengthening. After heat-treatment, γ’ was precipitated and it demonstrated the expected high strengthening behavior. Al, Ta and Ti partitioned to γ’. The strong partitioning of Ta in γ’ is indicative that the element, together with Al and Ti, was contributing to the strain-age cracking occurring during heat-treatment. Cr, Mo and Co partitioned to the matrix γ phase. Hf, Ta, Ti and W were found in the carbides corroborating previous reports that they are MC.

Partition of regular balanced c-tournaments into strongly connected c-tournaments

A multipartite tournament will be called r-balanced if every partite set has r vertices. The study of the existence of strongly connected subtournaments in multipartite tournaments started in 1999 by Volkmann. In this paper we study a much more general problem: the existence of a partition of a c-partite tournament into strongly connected tournaments of order c, which will be called strong partition. Given a positive integer r, the strong partition number, ST(r), is the minimum integer c′ such that every regular r-balanced c-partite tournament, with c≥c′, has a strong partition. We prove that for every r≥2, ST(r) exists and that 5≤ST(2)≤7. Moreover, as a consequence of our technique, for every r, there exists a c such that for every c′>c, there exists a strong partition into maximal tournaments of minimum degree ⌊c′−24⌋+1.

Shallow Sediment as a Phosphorus Reservoir in an Oligotrophic Lake

AbstractLake sediment is an important reservoir for storage of phosphorus (P). Skaneateles Lake, a pristine oligotrophic, midsize lake in New York State, USA, is the primary unfiltered water source for the city of Syracuse and nearby communities. We conducted a lake‐wide survey of shallow sediments in Skaneateles Lake to inform understanding of the potential role of sediment in P storage and release into the water column. A total of 103 shallow samples of surface sediments were collected along 17 transects around the lake margin and analyzed for sediment and pore water elemental concentration, grain size, total organic carbon, nitrogen, carbonate content, stable isotopes of carbon, and mineral content. Reduction‐oxidation (redox) processes of Fe‐bound and Mn‐bound P appear to be a primary control of P storage and release. Sediment P concentrations are positively correlated with water depth and negatively correlated with Ca. Grain size and sediment P distributions around the lake are heterogeneous and patchy. Pore water concentrations reveal strong but variable partitioning of P, apparently controlled by sediment redox conditions. Pore water P concentrations (mean 90 μg L−1) are elevated compared with the oligotrophic water column (∼5 μg L−1) and may be an important source of nutrients to the water column of the lake.

Increasing species richness along elevational gradients is associated with niche packing in bat assemblages.

The change in species richness along elevational gradients is a well-known pattern in nature. Niche theory predicts that increasing species richness in assemblages can either lead to denser packing of niche space ('niche packing') or an expansion into its novel regions ('niche expansion'). Traditionally, these scenarios have been studied using functional traits but stable isotopes provide advantages such as identifying the degree of resource specialisation, or niche partitioning among functionally similar species. In this study, we evaluate the relevance of niche packing versus niche expansion by investigating stable carbon and nitrogen isotopic niche width and overlap among 23 bat species from six functional groups across a 1500 m elevational gradient in the Himalaya. Our results suggest that an increase in species richness in the low elevation is accompanied by small niche width with high overlap, whereas the high elevation assemblage shows large niche width with low overlap among functional group members. At the functional group level, edge-space foraging, trawling, and active gleaning bats have the highest niche width while passive gleaning bats that are only found in high elevations are isotopic specialists showing low overlap with other groups. Edge and open-space foraging bats showed idiosyncratic changes in niche width across elevations. We also find that the niches of rhinolophid bats overlap with edge-space and open-space foraging bats despite their unique functional traits. These results support the idea that at low elevations high species richness is associated with niche packing while at high elevations strong niche partitioning prevails in dynamic and resource-poor environments. We conclude that although high elevation animal assemblages are often 'functionally underdispersed', that is show homogenous functional traits, our approach based on stable isotopes demonstrates niche partitioning among such functionally similar species.

Roles of pre-formed martensite in deformation behavior and strain partitioning of medium-carbon bainitic steel by quasi-in-situ tensile tests

Microstructural features play a major role in strain distribution and TRIP effect, influencing the plastic deformation behavior of multiphase steel. In this work, the bainitic multiphase microstructure with or without pre-formed martensite (PM) was obtained by the below-MS and above-MS austempering process. The evolution of strain partitioning and TRIP effect on plastic deformation were studied by combining micro digital image correlation (μ-DIC) analysis with in-situ tensile test in the multiphase microstructure. The changes of microstructure during deformation were systematically investigated by various characterization methods. The results show that the regions of strong strain partitioning in multiphase microstructure are different. Compared with the above-MS austempered sample without PM, the strain partitioning of the below-MS austempered sample containing PM is concentrated in the pre-formed martensite region while not in the blocky retained austenite (RA) region. The strain concentration in the PM region of the below-MS austempered sample is smaller than that in the blocky RA region of the above-MS austempered sample at the same engineering strain. The PM shares the stress load on RA during plastic deformation, thus can coordinate microstructure deformation and delay the early occurrence of the TRIP effect of the below-MS austempered sample. Moreover, the introduction of PM in the below-MS austempered sample increases the mechanical stability of RA, which is beneficial to produce an effective TRIP effect and delay necking to high strain. Consequently, the plasticity of the medium-carbon bainitic multiphase steel containing PM is enhanced by the effective TRIP effect and uniform strain partitioning.

Testing the context dependence of ant nutrient preference across habitat strata and trophic levels in Neotropical biomes.

Animals are integrated into the wider ecosystem via their foraging and behavior. The compensation hypothesis predicts that animals target their foraging efforts (i) toward nutrients that are scarce in the environment and (ii) toward nutrients that are not present in the usual diet of species, which varies across trophic levels. Understanding how foraging for resources varies locally, such as across habitat strata, and trophic levels will help to elucidate the links between the local environment and communities to the ecological functions that animals mediate. We examined whether the relative resource use of ants varies consistently along a habitat strata gradient and across trophic levels across Neotropical biomes. We placed 4500 baited tubes, each containing one of five liquid resources (sugar, amino acid, lipid, sodium, and distilled water) in one of three habitat strata (subterranean, epigaeic, and arboreal) across 60 transects in Amazon, Atlantic Forest, Caatinga, Cerrado, Pampa, and Pantanal biomes. We assessed the relative resource use of all ants across the habitat strata and among two different trophic groups across biomes. The relative preference for sugar increased from subterranean to arboreal strata in all biomes, while the relative preference for lipids decreased at this gradient in five biomes. We also found that in general sugar-consuming ants foraged more for sugar and less for lipids than predatory ants across biomes. Conversely, we found no consistency across biomes in nutrient preference of amino acid and sodium across habitat strata or trophic levels. Overall, our results indicate sugar limitation in the arboreal stratum and lipid limitation on the ground across biomes and that the trophic level of ants strongly determines their foraging efforts-possibly because ants try to fix their dietary nutrient imbalances. Hence, our findings suggest strong local niche partitioning of sugar and lipid use across habitat strata and trophic levels and that other large spatial scale processes influence the local amino acid and sodium dynamics.

Changes in Electrical Capacitance of Cell Membrane Reflect Drug Partitioning-Induced Alterations in Lipid Bilayer

The plasma membrane is a lipid bilayer that establishes the outer boundary of a living cell. The composition of the lipid bilayer influences the membrane's biophysical properties, including fluidity, thickness, permeability, phase behavior, charge, elasticity, and formation of flat sheet or curved structures. Changes in the biophysical properties of the membrane can be occasioned when new entities, such as drug molecules, are partitioned in the bilayer. Therefore, assessing drugs for their effect on the biophysical properties of the lipid bilayer of a cell membrane is critical to understanding specific and non-specific drug action. Previously, we reported a non-invasive technique for real-time characterization of cellular dielectric properties, such as membrane capacitance and cytoplasmic conductivity. In this study, we discuss the potential application of the technique in assessing the biophysical properties of the cell membrane in response to interaction with amiodarone compared to aspirin/acetylsalicylic acid and glucose. Amiodarone is a potent drug used to treat cardiac arrhythmia, but it also exerts various non-specific effects. Compared to aspirin and glucose, we measured a rapid and higher magnitude increase in membrane capacitance on cells under amiodarone treatment. Increased membrane capacitance induced by aspirin and glucose quickly returned to baseline in 15 s, while amiodarone-induced increased capacitance sustained and decreased slowly, approaching baseline or another asymptotic limit in ~2.5 h. Because amiodarone has a strong lipid partitioning property, we reason that drug partitioning alters the lipid bilayer context and subsequently reduces bilayer thickness, leading to an increase in the electrical capacitance of the cell membrane. The presented microfluidic system promises a new approach to assess drug-membrane interactions and delineate specific and non-specific actions of the drug on cells.

Experimental constraints on the behavior of Pt and Re in oxidized arc magmas

Highly siderophile elements such as Pt and Re are important tracers for Earth's crust–mantle differentiation. The behavior of Pt and Re in oxidized arc magmas are thought to be controlled by their strong partitioning into sulfides and/or magnetite. Disequilibrium fractionation of sulfide liquid was proposed to explain the Pt systematics in magmas when using sulfide liquid–silicate melt partition coefficients of Pt (DPtSul/Sil) of 105. However, the segregating sulfides are coexisting monosulfide-solid-solution (MSS) and Cu-rich sulfide liquid in thin island arcs, but mainly as MSS in thick continental arcs. Here we experimentally determine the MSS–silicate melt partition coefficients of Pt (DPtMSS/Sil) and magnetite–silicate melt partition coefficients of Re (DReMag/Sil) at 0.4–0.5 GPa, 1020–1100°C, and oxygen fugacity (fO2) from below FMQ-1.7 to ∼FMQ+2.5, using a piston cylinder apparatus. The results show that DPtMSS/Sil range between 20–8700 and increase with increasing Pt concentration (20–530 μg/g) in MSS at a given fO2, which can be explained by the presence of Pt-rich nuggets in MSS and the non-Henrian law behavior of DPtMSS/Sil. This finding suggests that Pt in oxidized arc magmas is much less chalcophile than previously thought. The obtained DReMag/Sil increase from 0.5 to 2.9 with fO2 decreasing from ∼FMQ+2.5 to FMQ+1, suggesting that Re is incompatible to slightly compatible in magnetite in oxidized arc magmas. Re dissolves as Re4+ in magnetite through the substitution of Re4+ + Fe2+ for 2Fe3+. The application of our new Ds together with previous Ds to a magmatic differentiation model, which involves an equilibrium fractionation of MSS and/or sulfide liquid, magnetite, and silicate minerals, can fully reproduce the evolution trends of Pt, Re, and Cu in oxidized, sulfide-saturated arc magmas. Our model results demonstrate that equilibrium fractionation of sulfides predominantly controls the behavior of Pt and Re in oxidized arc magmas with sulfide saturation.

In situ food compositions reveal niche partitioning in small marine cladocerans and copepods in Daya Bay, South China Sea

Marine cladocerans and small copepods (<0.7 mm) share similar food resources based on their size and feeding modes but little is known about the mechanisms allowing their coexistence. Using the high-throughput sequencing (HTS) method, the in situ eukaryotic diets of the small cladocerans Penilia avirostris and Pseudevadne tergestina and the calanoid copepod Parvocalanus crassirostris during spring and summer in Daya Bay, South China Sea, were analyzed and their dietary preference and potential niche overlap were described and compared. Approximately 195 operational taxonomic units belonging to metazoans, phytoplankton, protists, and fungi were detected in the gut contents of the 3 species. Overall, animal and phytoplankton prey contributed evenly to the sequences of gut contents of P. avirostris, with diatoms and cnidarians being the most important prey, whereas arthropods were the major prey resource for P. tergestina, with an extremely high percentage (86.2%). P. crassirostris contained a high percentage of phytoplankton prey, with dinoflagellates and diatoms as the major prey (24.3 and 12.9%, respectively). Both P. avirostris and P. crassirostris consumed a higher percentage of phytoplankton with the seasonal transition. Low niche overlap (0.001-0.19) among the 3 small crustaceans highlights their strong dietary niche partitioning and explains their coexistence in Daya Bay.

Heavy halogen compositions of lamprophyres derived from metasomatized lithospheric mantle beneath eastern North China Craton

Abstract Halogens and other volatiles are widely recycled into the deep mantle by subduction and are key components to metasomatize the sub-continental lithospheric mantle (SCLM). Lamprophyres are well known to be rich in volatiles and are important for understanding the halogen characteristics of the meta-somatized SCLM and/or the mobilization of halogens during the ascent of such volatile-rich, low-degree partial melts. The North China Craton (NCC) hosts lamprophyre dikes coeval with extensive thinning of the eastern NCC in the Mesozoic and generated from lithosphere metasomatized by multiple-stage subduction components. Here we report bulk-rock heavy halogens (Cl, Br, and I) of 16 lamprophyres from the eastern NCC. The bulk-rock halogen concentrations are overall very low (Cl = 58–170 μg/g, Br = 285–559 ng/g, and I <5 ng/g), comparable with depleted Mid-Ocean ridge basalts (N-MORBs). Volatile-rich minerals (e.g., amphibole and biotite) are abundant (20–30 vol%) in these lamprophyres, however, electron probe microanalyses (EPMA) data indicate that amphiboles are mainly rich in OH and F but display very low Cl concentrations (0.01–0.04 wt%). The bulk rock and amphibole data consistently indicate low abundances of heavy halogens in the lamprophyres, which is difficult to reconcile with the remarkable enrichment of fluid-mobile large ion lithophile elements such as Ba, Rb, and K. Based on low Cl/Nb and Br/Nb but high Ba/Nb and K/Nb ratios, the low halogen concentrations likely resulted from extensive volatile loss (>90%) during melt ascent. The low Cl concentrations in early-stage amphiboles (Mg# 60–64) further indicate that such loss would have occurred before amphibole crystallization at a depth of ~15 km. We thus propose that crystallization of early olivines and pyroxenes and reaction with surrounding mantle rocks likely induced volatile saturation and exsolution, leading to strong partitioning of the halogens into the exsolved aqueous volatile phases and thus the extensive loss of halogens from the rising melt. These results reveal that significant volatile loss of halogens not only occurs during surficial low-pressure eruption but also at much deeper levels in the crust, as also identified for some kimberlites. Consequently, it would be difficult to constrain the primitive halogen components of the mantle sources via lamprophyres or similar magmas.

Dominator semi strong color partition in graphs

Let GG =(V,E)(V,E) be a simple graph. A subset SS is said to be Semi-Strong if for every vertex vv in VV, |N(v)∩S|≤1|N(v)∩S|≤1, or no two vertices of SS have the same neighbour in VV, that is, no two vertices of SS are joined by a path of length two in VV. The minimum cardinality of a semi-strong partition of GG is called the semi-strong chromatic number of GG and is denoted by χsGχsG. A proper colour partition is called a dominator colour partition if every vertex dominates some colour class, that is , every vertex is adjacent with every element of some colour class. In this paper, instead of proper colour partition, semi-strong colour partition is considered and every vertex is adjacent to some class of the semi-strong colour partition.Several interesting results are obtained.

Composition design of a novel Ti-6Mo-3.5Cr-1Zr alloy with high-strength and ultrahigh-ductility

• A novel titanium alloy with high strength and ultrahigh ductility was designed to break through the longstanding strength-ductility trade-off. • The strong strain partitioning effect and the dislocation pile-up effect caused by SIω were found and quantitatively analyzed by in situ EBSD/DIC and in situ TEM tests, respectively. • The TRIP/TWIP/DPU coupling effect during plastic deformation was firstly proposed and deciphered. The strength-elongation to fracture ( ε f ) trade-off and low strain hardening rate have been a longstanding dilemma in titanium alloys. In this work, we innovatively manufactured a novel Ti-6Mo-3.5Cr-1Zr alloy via the introduction of a stress-induced strengthening phase into the material. Stress-induced ω (SI ω ) phase transformation was expected to replace the α'' martensitic transformation that resulted in the low yield strength of titanium alloys. The obtained alloy exhibited an extremely high strain hardening rate of up to ∼1820 MPa. The true peak tensile strength and ε f reached ∼1242 MPa and ∼40%, respectively. The intrinsic mechanisms underlying the simultaneous improvement of strength and ductility of the material were systematically investigated via in-situ and ex-situ characterizations. In-situ electron backscatter diffraction (EBSD)/digital image correlation (DIC) results showed that SI ω phase transformation dominated the early stage of plastic deformation (1.5%–3%) and promoted the strain partitioning between the stress-induced bands and β matrix. Subsequently, the formation of {332}<113> β twins and ω twins was observed via ex-situ EBSD. In-situ transmission electron microscopy results revealed that dislocation pile-up (DPU) occurred at the SI ω / β interface. The coupling effects associated with the transformation induced plasticity (TRIP), twinning induced plasticity (TWIP), and DPU mechanisms contributed to the enhanced strength and ε f of the designed titanium alloy.

Model-driven development for the seL4 microkernel using the HAMR framework

Verified microkernels such as seL4 provide trustworthy foundations for safety- and security-critical systems. However, their full potential remains unrealized due, in part, to the lack of application development environments that help engineers integrate the microkernel’s configuration and hosting of application code with modeling, analysis, and verification tools that address broader aspects of the development lifecycle.This paper presents a model-driven tool chain for the seL4 microkernel based on the open source High Assurance Modeling and Rapid engineering (HAMR) code generation framework for the Architecture and Analysis Definition Language (AADL). We describe how the semantics of AADL communication and threading can be realized in terms of the access primitives and strong spatial and temporal partitioning mechanisms provided by seL4. For AADL users, seL4 provides a high-assurance platform with formally verified enforcement of component boundaries and communication pathways. For seL4 users, AADL provides high-level abstractions for developing seL4 applications, along with an ecosystem of system engineering and analysis tools. We illustrate the framework by applying a model-based development environment for increasing resiliency against cyber attacks to an unmanned aircraft flight control system.

Influence of stress-induced α’’ phase transformation on mechanical properties in metastable β type Ti-5Al-2.5Cr-5Mo-1Sn alloy

The stress-induced α’’ phase transformation in titanium alloys has received extensive attention due to its significant effect on mechanical properties. In this work, by adjusting the heat treatment process, the stress-induced α’’ phase transformation is activated in Ti-5Al-2.5Cr-5Mo-1Sn. The quasi-static tensile mechanical properties of the alloy under air-cooled and as-quenched states have been compared. Further, the morphology and orientation of the stress-induced α’’ phase and its interaction with dislocations are investigated by X-ray diffraction (XRD), optical microscope (OM), electron backscattered diffraction (EBSD) and transmission electron microscope (TEM) experiments. The value of average misorientation at the stress-induced α’’ bands region is larger than that in the β matrix, which indicates that the degree of plastic deformation in the stress-induced phase transformation region is higher. Therefore, the stress-induced α’’ phase exhibits a strong strain partitioning effect during the stretching process and improves the ductility of the material. The β/α’’ interface has a weak effect to hinder the dislocations, which results in low tensile strength of the alloy. This work can provide insight into the influence of stress-induced α’’ phase transformation on the mechanical properties of transformation induced plasticity (TRIP) type titanium alloys. • The Ti-5Al-2.5Cr-5Mo-1Sn alloy is elaborately regulated to produce TRIP effect. • Average misorientation of α’’ band region is generally larger than that of β matrix. • α’’ phase exhibits a strong strain partitioning effect to increase alloy ductility. • The β/α’’ interface is semi-coherent and has a weak effect to hinder dislocations.

Investigation on two-phase flow-induced vibrations of a piping structure with an elbow

The dynamic behaviors of a horizontal piping structure with an elbow due to the two-phase flow excitation are experimentally investigated. The effects of flow patterns and superficial velocities on the pressure pulsations and vibration responses are evaluated in detail. A strong partition coupling algorithm is used to calculate the flow-induced vibration (FIV) responses of the pipe, and the theoretical values agree well with the experimental results. It is found that the lateral and axial vibration responses of the bend pipe are related to the momentum flux of the two-phase flow, and the vibration amplitudes of the pipe increase with an increase in the liquid mass flux. The vertical vibration responses are strongly affected by the flow pattern, and the maximum response occurs in the transition region from the slug flow to the bubbly flow. Moreover, the standard deviation (STD) amplitudes of the pipe vibration in three directions increase with an increase in the gas flux for both the slug and bubbly flows. The blockage of liquid slugs at the elbow section is found to strengthen the vibration amplitude of the bend pipe, and the water-blocking phenomenon disappears as the superficial gas velocity increases.

Spatiotemporal relationships of coyotes and free-ranging domestic cats as indicators of conflict in Culver City, California.

As habitat generalists, urban coyote (Canis latrans) populations often utilize an abundance of diverse food sources in cities. Within southern California, domestic cats (Felis catus) comprise a higher proportion of coyote diets than in other studied urban areas throughout the United States. However, it is unclear which ecological factors contribute to higher rates of cat depredation by coyotes in this region. While previous research suggests that coyote presence may have a negative effect on free-ranging domestic cat distributions, few studies have determined whether urban green spaces affect coyote or free-ranging domestic cat occurrence and activity within a predominantly urbanized landscape. We placed 20 remote wildlife cameras across a range of green spaces and residential sites in Culver City, California, an area of Los Angeles County experiencing pronounced coyote-domestic cat conflict. Using data collected across 6 months from 2019–2020, we assessed the influence of green space and prey species (i.e., cottontail rabbits (Sylvilagus spp.) and domestic cats) on coyote habitat use and activity. Coyotes exhibited a preference for sites with higher amounts of green space, while domestic cat habitat use was high throughout our study region. Although cottontail rabbit habitat use was also highly associated with urban green space, neither cottontails nor domestic cats appeared to temporally overlap significantly with coyotes. Unlike other cities where coyotes and domestic cats exhibit strong habitat partitioning across the landscape, domestic cats and coyotes spatially overlapped in green space fragments throughout Culver City. We suggest that this pattern of overlap may be responsible for the frequent cases of domestic cat depredation by coyotes in Culver City.

Kinetically Induced Fine Secondary α-Ti Phase Formation in a Novel As-Cast Titanium Alloy

The formation of fine secondary hexagonal close packed (HCP) α-Ti precipitates provides major strengthening in a new Ti-6Al-5Fe-0.05B-0.05C (mass fractions in pct) cast alloy. The phase transformation mechanisms from the body-centered cubic (BCC) β-Ti matrix to fine α phase in this new α-β titanium alloy were investigated experimentally and computationally using CALculation of PHAse Diagram (CALPHAD)-based thermodynamic and kinetic models. The discrete distribution of α precipitates was observed in the as-cast alloy with evidence of strong Fe partitioning. Two main size groups of α precipitates and the Fe partitioning were characterized using scanning electron microscopy, scanning transmission electron microscopy, and synchrotron-based small-angle X-ray scattering techniques. A hypothesis of Fe-partitioning driven α precipitate nucleation and growth was validated by precipitation simulation using TC-PRISMA with customized thermodynamic and kinetic descriptions. These results suggested a new titanium alloy design route involving high-mobility elements (enhancing fine secondary α precipitates) and demonstrated the capability of CALPHAD-based modeling in titanium alloy design.

Effects of minor Nb alloying on the thermal stability and mechanical responses of a γ/γ′ type high-entropy alloy with high Fe content

In this work, by equipping the high-entropy concept we designed a γ/γ′-type high-entropy alloy with high Fe content (25 at.%), and further alloyed Nb to evaluate its microstructural stability and mechanical responses. We found that after 850 °C annealing, 1.5 at.% Nb addition can completely suppress the discontinuous precipitation (DP) reaction. The high γ/γ′ structural stability even after one month ageing at 800 °C is believed to be originated from strong partitioning of Nb to γ′. The onset of continuous inter-mass-flow of Fe and Nb across the γ/γ′ interface further enhances the γ′ ripening resistance. The increased tensile strength in the Nb-alloyed HEA across a wide temperature range (23–900 °C) is because of the increased volume fraction and anti-phase boundary energy of γ′. The corresponding lowered ductility is then attributed to the absence of the DP colony that not only acts as a stress buffer zone but also introduces grain boundary serration to withstand intergranular cracking.

Novel insights on the near atomic scale spatial distributions of substitutional alloying and interstitial impurity elements in Ti-6Al-4V alloy

The present study explores the near atomic scale spatial distributions of substitutional alloying elements (aluminium and vanadium) and interstitial impurities (oxygen and carbon) in the microstructures of Ti-6Al-4V and its boron modified counterpart (Ti-6Al-4V-0.1B) alloys using transmission electron microscopy (TEM) and atom probe tomography (APT) techniques. The latter alloy possesses zero solubility of boron in α-Ti and high oxygen concentration around TiB particles. The results suggest that aluminium and vanadium atoms enrich α and β phases, respectively due to strong elemental partitioning between these phases, to an extent that the atomic scale concentrations of various elements considerably differ from the bulk compositions of the two alloys. Furthermore, oxygen atoms are preferentially distributed within the α phase where other interstitial impurities (carbon) also segregate. Substitutional aluminium atoms share an inverse interrelation with interstitial oxygen atoms while vanadium atoms reside besides the impurity-rich regions for both the alloys. The size differences for these elements (substitutional vs. interstitial) with host titanium atoms and related lattice distortion is (partially) held responsible for the atomic scale elemental distributions and the observed interrelations within the α phase. These arguments are further substantiated from DFT results previously obtained for Ti-6Al-4V alloy.

Effect of fuzziness in fuzzy rule-based classifiers defined by strong fuzzy partitions and winner-takes-all inference

We study the impact of fuzziness on the behavior of Fuzzy Rule-Based Classifiers (FRBCs) defined by trapezoidal fuzzy sets forming Strong Fuzzy Partitions. In particular, if an FRBC selects the class related to the rule with the highest activation (so-called Winner-Takes-All approach), then fuzziness, as quantified by the slope of the membership functions, has no impact in classifying data in regions of the input space where rules dominate. On the other hand, fuzziness affects the behaviour of the FRBC in regions where the confidence in classification is low. As a consequence, in the context of Explainable Artificial Intelligence, fuzziness is profitable in FRBCs only if classification is accompanied by an explanation of the confidence of the provided outputs.