Fundamental Structural Elements Research Articles

Initial performance assessment of 3D printed thin walled structures for spacecraft applications

Sandwich panels are the fundamental structural element in a wide range of applications, including in satellite primary structures. While sandwich constructions are very efficient, their complex multi-material assembly leaves room for further optimisation of the core volume and improvement in the integration phase. One key technology that can enable the transition to multifunctional sandwich panel cores tailored to certain applications is the additive manufacturing (AM) of satellite primary structure sandwich panel cores. This paper investigates the feasibility of replacing the baseline Aluminium honeycomb core with a core printed out of AlSi10Mg through Powder Bed Fusion. Sandwich panels with carbon fiber-reinforced plastic (CFRP) facesheets and printed honeycomb cores as well as fully printed corrugated panels are produced and tested under three point bending (3PB) and compression as part of the EU funded ReDSHIFT project. The Instron 5560 (3PB) and 4204 (compression) are used to perform the experiments that follow the ASTM C393-11 and C365 standards. When compared against the baseline CFRP-AL panels, the 3D printed honeycomb cores carry up to twice as much load per unit mass in bending and four times as much in compression, while also being stiffer. The fully printed corrugates samples are weaker than the honeycombs, but in conjunction with the honeycomb geometry may present a promising avenue for developing multifunctional cores. While limitations with current metal printing technology prevent AM cores from matching the mass of baseline designs, the superior specific performance and geometrical freedom make printed cores a promising design alternative.

Effects of KoBo-Processing and Subsequent Annealing Treatment on Grain Boundary Network and Texture Development in Laser Powder Bed Fusion (LPBF) AlSi10Mg Alloy

It is well known that the properties of polycrystalline metals are related to grain boundaries (GBs), which are fundamental structural elements where crystallographic orientations change abruptly and often exhibit some degree of symmetry. Grain boundaries often exhibit unique structural, chemical, and electronic properties that differ from bulk crystalline domains. Their effects on material properties, including mechanical strength, corrosion resistance, and electrical conductivity, make grain boundaries a focus of intense scientific investigation. In this study, the microstructural transformation of an AlSi10Mg alloy subjected to KoBo extrusion and subsequent annealing is investigated. A notable discovery is the effectiveness of a strain-annealing method for grain boundary engineering (GBE) of the LPBF AlSi10Mg alloy. In particular, this study shows a significant increase in the population of coincidence site lattice boundaries (CSL), which embody the symmetry of the crystal lattice structure. These boundaries, which are characterised by a high degree of symmetry, contribute to their special properties compared to random grain boundaries. The experimental results emphasise the crucial role of strain-induced boundary migration (SIBM) in the development of a brass texture in the microstructure of the alloy after annealing. In addition, the presented results demonstrate the feasibility of applying GBE to materials with high stacking fault energy (SFE), which opens up new possibilities for optimizing their properties.

Advances in chromone-based copper(ii) Schiff base complexes: synthesis, characterization, and versatile applications in pharmacology and biomimetic catalysis.

Chromones are well known as fundamental structural elements found in numerous natural compounds and medicinal substances. The Schiff bases of chromones have a much wider range of pharmacological applications such as antitumor, antioxidant, anti-HIV, antifungal, anti-inflammatory, and antimicrobial properties. A lot of research has been carried out on chromone-based copper(ii) Schiff-base complexes owing to their role in the organometallic domain and promise as potential bioactive cores. This review article is centered on copper(ii) Schiff-base complexes derived from chromones, highlighting their diverse range of pharmacological applications documented in the past decade, as well as the future research opportunities they offer.

Quantitative characterisation of fracture connectivity from high-resolution borehole image logs

Fractures are fundamental structural elements in brittle rocks. They have a primary role in transporting geofluids, particularly in basement and carbonate rocks, where they have been the focus of reservoir characterisation and modelling for decades. Fracture networks are often described by statistical analysis of their geometrical attributes such as orientation, length and aperture. However, the spatial arrangement (topology) of fractures/fracture sets and its temporal evolution is equally important to better understand physical attributes of rocks. How much is a fracture network connected? Can this be quantified? Does connectivity change in different locations, if yes what is the reason for it? What is the brittle strain distribution in a fracture network? How much are fracture density and connectivity influenced by mechanical stratigraphy?This paper attempts to address these relevant questions and test quantitative fracture connectivity analysis on high resolution electrical and ultra-sonic borehole image logs in an appraisal well (Total depth, TD: 2195.36 mMD), drilled into the Utsira High basement, in the extensional Norwegian North Sea rift basin. Fracture connectivity and fracture size attributes were investigated in Permian Zechstein carbonates and Ordovician-Silurian granitic basement and separately for defined fracture zones at the interval of 2050–2195 mMD. The average degree of fracture/fault connection is good (D = 2.6) for the sediments and excellent (D = 3.5) for the basement. Accordingly, the block intensity (R22) is 0.4 for sediments and 0.2 for basement, which imply a moderately and strongly disintegrated host rock, respectively. There is a large fracture connectivity variation in different fracture zones, i.e. completely isolated fractures (Zone 1) vs highly interconnected and strongly disintegrated basement (Zones 9–10). The connectivity variation is governed by lithology, mechanical properties (stiffness), strain distribution and presence of weakness zones (faults). The study also highlights some possible applications of fracture connectivity results to reservoir modelling and future follow-up trends in quantitative spatial characterisation of fracture networks.

Mechanics of isolated individual collagen fibrils.

Collagen fibrils are the fundamental structural elements in vertebrate animals and compose a structural framework that provides mechanical support to load-bearing tissues. Understanding how these fibrils initially form and mechanically function has been the focus of a myriad of detailed investigations over the last few decades. From these studies a great amount of knowledge has been acquired as well as a number of new questions to consider. In this review, we examine the current state of our knowledge of the mechanical properties of extant fibrils. We emphasize on the mechanical response and related deformation of collagen fibrils upon tension, which is the predominant load imposed in most collagen-rich tissues. We also illuminate the gaps in knowledge originating from the intriguing results that the field is still trying to interpret. STATEMENT OF SIGNIFICANCE: Collagen is the result of millions of years of biological evolution and is a unique family of proteins, the majority of which provide mechanical support to biological tissues. Cells produce collagen molecules that self-assemble into larger structures, known as collagen fibrils. As simple as they appear under an optical microscope, collagen fibrils display a complex ultrastructural architecture tuned to the external forces that are imposed upon them. Even more complex is the way collagen fibrils deform under loading, and the nature of the mechanisms that drive their formation in the first place. Here, we present a cogent synthesis of the state-of-knowledge of collagen fibril mechanics. We focus on the information we have from in vitro experiments on individual, isolated from tissues, collagen fibrils and the knowledge available from in silico tests.

Digital Toolkit to Assist the Interpretation of Traditional Masonry Construction

ABSTRACT Masonry construction is ubiquitous and is most typically employed for the construction of fundamental structural architectural elements. It is thus extremely important in architectural conservation, and visual survey, recording and documentation often start with such primary elements. Recording has, however, traditionally been a laborious manual process yielding variable and subjective outcomes. This situation is exacerbated by the need to involve experts to interpret the recorded data, which further increases costs. Recent and ongoing advances in digital reality capture and computer vision afford notable advantages in extracting value from point cloud data with benefits to conservative repair, maintenance, and wider architectural intervention. In this paper, we build on our previous research by the authors and present bespoke algorithms brought together as a ‘digital toolkit’ to automatically segment point clouds into individual masonry units and further characterisation of each unit to support architectural interpretation. The use of this digital toolkit is illustrated using a wall section of Linlithgow Palace (Scotland, UK) as a case study, but it must be emphasised that this form of construction typifies innumerable buildings globally. The toolkit has shown to facilitate rapid and systematic identification of change in masonry construction styles, sizes and geometry, and, when used in conjunction with traditional survey evaluation, it meaningfully assists interpretative capabilities. This combined approach is termed ‘digitally assisted analytical recording’ and it offers the promise of yielding more cost-effective, accurate survey for interpretation.

Architected material with independently tunable mass, damping, and stiffness via multi-stability and kinematic amplification.

We report on a class of architected material lattices that exploit multi-stability and kinematic amplification to independently adjust the local effective mass, damping, and stiffness properties, thereby realizing congruent alterations to the acoustic dispersion response post-fabrication. The fundamental structural tuning element permits a broad range in the effective property space; moreover, its particular design carries the benefit of tuning without altering the original size/shape of the emerging structure. The relation between the tuning element geometry and the achieved variability in effective properties is explored. Bloch's theorem facilitates the dynamic analysis of representative one- and two-dimensional (1D/2D) systems, revealing, e.g., bandgap formation, migration, and closure and positive/negative metadamping in accordance with the tuning element configuration. To demonstrate a utility, we improvise a waveguide by appropriately patterning the tuning element configuration within a 2D system. We believe that the proposed strategy offers a new way to expand the range of performance and functionality of architected materials for elastodynamics.

Spatio‐temporal patterns in the woodiness of flowering plants

AbstractAimWoody and herbaceous habits represent one of the most distinct contrasts among angiosperms, and the proportion of woody species in floras (i.e., “woodiness” hereafter) represents a fundamental structural element of plant diversity. Despite its core influence on ecosystem processes, spatio‐temporal patterns in woodiness remain poorly understood. Here, we aim to demonstrate the global spatio‐temporal patterns in angiosperm woodiness and their relationship with environmental factors.LocationGlobal.Time periodCenozoic, 66 Ma to present.Major taxa studiedAngiosperms.MethodsUsing newly compiled data on the growth forms and distributions of c. 300,000 angiosperm species and an angiosperm phylogeny, we mapped the current global geographical patterns in angiosperm woodiness, reconstructed ancestral states of growth forms through the angiosperm phylogeny and demonstrated the Cenozoic evolutionary dynamics of woodiness. We evaluated the relationships between woodiness and current climate and palaeoclimate.ResultsWe found that c. 42.7% of angiosperms are woody. Woodiness decreased spatially from the equator towards high latitudes, temporally since the early Cenozoic. Temperature was the best predictor of the spatio‐temporal decline in woodiness and was positively correlated with woodiness. Despite the temporal decline in woodiness, macroevolutionary herbaceous‐to‐woody transitions increased through time and contributed to the evolution of woody floras in temperate drylands, whereas the opposite transitions decreased through time and contributed to herbaceous floras in tropical and subtropical drylands.Main conclusionsOur study improves understanding of the spatio‐temporal dynamics of angiosperm woodiness. Our findings suggest that temperature is likely to be a determinant of spatio‐temporal variations in woodiness, highlighting the role of temperature in maintaining the growth form composition of ecosystems. Our study also calls for attention to growth form transitions (e.g., secondary woodiness) in temperate drylands that have been neglected before.

АНАЛИЗ ПРОБЛЕМ ЗАЩИТЫ ИНФОРМАЦИИ В СЕМАНТИЧЕСКИХ СЕТЯХ

The article analyzes the structure, principles and technologies used in the creation of semanticnetworks, the methodology for representing knowledge in a semantic network. Specialattention is paid to the analysis of the structure of queries to data stored in the semantic network.The purpose of the analysis is to determine the structural elements that carry confidential or otherimportant information for the further formation of a methodology for its protection, consideringthe specifics of the semantic network. As a result of the analysis of typical structures of semanticnetworks, the fundamental structural elements and concepts that make up the structure of the analyzedmethod of knowledge representation are considered. The specialized languages used for itsconstruction and the structure of the information request to the knowledge base are determined, inwhich elements carrying confidential information and potentially vulnerable to attacks by intruderswere identified. Problems in the information security of semantic networks have been identified,such as: exposure to malicious SPARQL queries, which can be used to obtain informationfrom the semantic network without appropriate privileges and accesses; data vulnerability in thetransmitted information request, characterized by a weak focus of existing protection methods onthe specifics of semantic networks; the problem of assessing the level of confidence in the receiveddata of the semantic network. One of the approaches to solve these problems can be the creationof a distributed system for evaluating the trust in nodes and data in the semantic network, as wellas the implementation of mechanisms for protecting information and information requests.The results obtained as a result of the analysis on the structure of the transmitted data are an integralpart of the process of developing information security tools in semantic networks.

Influence of geometric parameters and material properties of the reinforcing core on the modal properties of vibrating beam structures

The beam structures are considered as fundamental structural elements that are widely used in mechanical and building structures. One of the important tasks in the structural design of beam structures should be the ability to prevent or reduce the level of unwanted vibrations. It is obvious that the dynamic properties of beam structures depend on their shape structure, i.e. from their geometric parameters and material properties. Usually, the beam structures have constant cross-section and made of homogeneous material. However, these structures in many cases do not have the required dynamic properties. The design and analysis of the beam structures that will allow its spatial properties (mass and stiffness) to be redistributed using the sliding core inserted into the beam structure is investigated in this paper.

Bipolar Plate Flow Field Structure Research Status and Trends for Hydrogen Fuel Cell Vehicles

The bipolar plate is the fundamental structural element of the hydrogen fuel cell, and its flow field design has a significant impact on the performance of the fuel cell. The hydrogen fuel cell is employed as an important energy supply source for vehicle power. The classification and operation of hydrogen fuel cells, as well as the benefits and drawbacks of conventional flow fields, are discussed in this paper and contrasted with the state of bipolar plate flow field research in recent years. Comprehensive analysis is done on the optimization of the fuel cell bipolar plate flow field based on the conventional flow field. All are favorable to enhancing fuel cells' ability to generate electricity and aid in the progressive development of a full set of structural design guidelines.

Urban expansion of the 43 worlds’ largest megacities: A search for unified macro-patterns

In this article, we make the case for the existence of global macro-patterns of urban change and urban growth, in particular, which may be recognized across metropolitan systems located around the globe. In order to achieve these goals, we examine the pace and types of built-up land expansion inside metropolitan regions of the 43 major megacities in the globe between 1985 and 2015. We show that the advancement of the urbanization-metropolisation process involves the sequential co-occurrence of three urban growth modes (outlying, edge expansion, and infilling). It refutes earlier claims that the three expansion modes occur simultaneously (concurrent co-occurrence) and supports the diffusion-coalescence hypothesis of urbanization. Additionally, we suggest a straightforward model based on the urban scaling laws that can be used to predict the growth of new built-up land in metropolitan areas based on the current urban mass (agglomeration effect), the availability of undeveloped land (hinterland effect), and fundamental structural elements of wider settlement systems (national-level urbanization rate and fertility). We find that the agglomeration effect is crucial for urban infilling while the hinterland effect has a greater impact on edge expansion and outlying growth. We also predict that built-up land inside the administrative regions of the studied megacities will expand by 15% (11,000 sq. km.) between 2015 and 2030. Our research thereby advances knowledge of the physical development of urban systems.

Innovation of Shear Connectors in Slim Floor Beam Construction

Composite slim floor systems are increasingly applied in the construction industry. Therefore, several experimental and numerical studies have been conducted to investigate the composite flooring systems and examine the various details that may affect the production of composite floors. This review paper summarises some important developments of composite slim floor beams, such as the type of steel beam cross section and shear connectors used, presenting essential results and important notes from various studies. The fundamental structural elements and the contribution of conducted studies towards improving the shear capacity of composite beams in enhancing the general structural behaviour were also described. Finally, the paper concludes with the potential of a deeper investigation of some issues that accompany the application of certain types of shear connects or steel shapes used to improve the composite slim floor system so that the improvement construction industry may make the most out of using composite construction techniques.

ARTISTIC IMAGERY AS PHENOMENON CREATION ANALITICAL MEANS IN DIFFERENT KINDS OF ARTS

The article treats artistic imagery from the point of view of its ability to analyse phenomenon of creation. The author states that not only scientific categories can analyse it but artistic image also can do it none the worse, and discover such aspects in the essence of phenomenon of creation that science did not consider yet. It is proved by analyses of XIX-XX century works of worldwide authors in different spheres of artistic creation: literature in prose and poem forms (Pushkin, Joyce, Sarraute, Tsvetaeva); dramaturgy (Tchechov, Bekket, Ionesco); cinema ( Fellini, Tarkovsky); painting (Picasso).The author finds links between their images using such analytical methods as structural, semiotics and comparison ones, and author’s method of metatextual invariability. It makes possible to find fundamental structural elements as invariants of analysed artistic systems. Each of them develops in his own way invariants’ semantics concerning creation phenomenology notably that of artist’s seeking his individual language as expression of his reality subjective viewing. What kind of phenomena happen then in the artist’s soul can discover only artistic imagery means; scientific categories are powerless of doing it.. The author points out at the whole set of symbols which are used as phenomenon creation analytical means in artistic discourse.

Numerical Simulation of Some Steel Structural Elements with Uncertain Initial Porosity

The main research purpose of this work was to study the elasto-plastic responses of some fundamental steel structural elements exhibiting stochastic volumetric microvoids. The constitutive model of the steel material was consistent with the deterministic Gurson–Tvergaard–Needleman (GTN) porous plasticity model, where some of the microvoids parameters have additionally been defined as Gaussian random variables. The iterative stochastic finite element method implemented based on the-tenth order stochastic perturbation technique was utilized in numerical experiments. An interoperability of the computer algebra system MAPLE 2019 and the finite element method system ABAQUS was employed to study the influence of the initial microvoids f0 with uncertainty in the structural steel on the statistical scattering of the resulting stresses and deformations. The basic probabilistic characteristics of the structural response were computed and contrasted with statistical estimators inherent in the Monte–Carlo simulation and also with the results obtained from the semi-analytical probabilistic method. Reliability indices according to the first-order reliability method (FORM) were also calculated. Two numerical illustrations included the (i) tension test of the round cylindrical steel rebar and the (ii) bending test of the steel I-beam restrained at both its ends. Expectations and coefficients of variation of the structural responses confirmed here the importance of the microvoids for the stochastic elasto-plastic behavior of some basic engineering structures, where tensile stress plays an important role in designing procedures.

Auf ein Neues? Erfolgsfaktoren für die Konferenz zur Zukunft Europas

In this article, the author contrasts the experience of the Convention on the Future of Europe 2002-2003 with the mandate for the Conference on the Future of Europe which commenced on May 9, 2021. He criticises that the Conference is deprived of fundamental structural elements that were success factors for the Convention: a clear mandate, a tight leadership, and the right to self-organise. Nevertheless, the author is convinced that the Conference still has every chance of giving the European Union a forward-looking impetus for reform. He derives five recommendations for the future work of the Conference. In particular, it must be set up considering the desired outcome, by defining a product that is to be established, and directing the work toward its creation. If the Conference serves solely as a sounding board for diffuse citizen concerns, its potential cannot be fully exploited.

Seeing with the Pandemic: Social Reproduction in the Spotlight

492 Feminist Studies 47, no. 3. © 2021 by Feminist Studies, Inc. Leslie Salzinger Seeing with the Pandemic: Social Reproduction in the Spotlight The COVID-19 pandemic has inverted capitalism’s normal visibilities, bringing what were negative spaces to the fore and throwing the work of social reproduction into stark relief. Decades of neoliberal governance have scrapped state support for care and increased the pressures on families where every adult is working for pay. In response, reproductive labor has been commodified and racialized at scale, and those who care for and nourish others, whether unwaged or waged, have been left holding the bag for society as a whole. The virus’s incursion has thrown a harsh light on this non-system. From the New York Times to Twitter to grocery lines, both pundits and private citizens have begun to take note of the labor it takes to make and sustain human life as well as the unfreedom of those who perform that labor. But even as appreciation washes through, reproductive care workers are increasingly stepping out to say that garlands are not enough.1 This emergent public reckoning comes on the heels of an extended scholarly rethinking of capitalism, as a growing group of scholars argue that capitalism is always already embedded in gendered and racialized 1. Karleigh Frisbie Brogan, “Calling Me a Hero Only Makes You Feel Better,” The Atlantic, April 18, 2020. Leslie Salzinger 493 relations of extraction and expropriation.2 Especially generative has been Karl Marx’s remarkable historical account of capitalism’s origins in a process he dubbed “primitive accumulation.”3 Intent on forestalling moralistic justifications for the system’s origins, Marx argued that elites used a combination of land expropriation and violent vagrancy policing to produce both the starter capital and the “free labor” needed to bring that capital to life. Since Rosa Luxemburg, scholars have expanded that account to challenge the more abstract and teleological formulations contained in other parts of Marx’s larger oeuvre.4 Rather than see primitive accumulation as focused exclusively on domestic processes and ownership relations , subsequent theorists have pointed to the transnational, racialized , colonial, and gendered processes that characterized its emergence, along with the persistence of these putatively time-limited processes throughout capitalism’s existence.5 Prompted by the deep inequities of neoliberalism, David Harvey has argued that the present, in fact, is best understood as a new episode of primitive accumulation, which he names “accumulation by dispossession.”6 These historical rereadings suggest that national ownership relations have never exhausted the range of power relations under capitalism and that the relationships between capital and other structures of power are historically contingent . Marx’s more elegant formulations notwithstanding, exploitation operated from the outset on a bed of racialized, colonial, and gendered 2. See especially Silvia Federici, Caliban and the Witch: Women, the Body and Primitive Accumulation (New York: Autonomedia, 2004); Maria Mies, Patriarchy and Accumulation on a World Scale (London: Zed Books, 1986); Cedric J. Robinson, Black Marxism: The Making of the Black Radical Tradition (Chapel Hill: University of North Carolina Press, 2000); and Nikhil Pal Singh, “On Race, Violence, and So-Called Primitive Accumulation,” Social Text 34, no. 3 (September 2016): 27–50. 3. Karl Marx, “Primitive Accumulation” in Capital: A Critique of Political Economy , vol. 1 of 8 (Moscow: Progress Publishers, 1867; New York: Vintage, 1977). 4. Rosa Luxemburg, The Accumulation of Capital, trans. Agnes Schwarzschild (1913; New York: Routledge, 2003). 5. For an illuminating reanalysis of primitive accumulation, see Robert Nichols , Theft Is Property! Dispossession and Critical Theory (Durham, NC: Duke University Press, 2019). 6. David Harvey, “Neoliberalism as Creative Destruction,” The Annals of the American Academy of Political and Social Science 610 (March 2007): 22–44. 494 Leslie Salzinger relations, which were themselves reconfigured, solidified, and sustained by those interactions. This distinct understanding of capitalism as a system throws new light on the present. I will argue here that constitutively gendered and racialized social reproduction is one arena where primitive accumulation continues to operate within capitalism as a fundamental structural element of the system itself. The production of people is an arena of vital unpaid, underpaid, and formally unrecognized work that makes all the rest possible. It...

Managing A Veterinary Practice: A Guide To Organizational Culture In Veterinary Practice

The veterinary profession in Germany is undergoing a fundamental change. While the number of small practices is decreasing, the number of larger group, partnership or corporate practices is increasing. This makes competition among veterinarians even greater. But not only the market itself is changing. The humanization of pets, digitalization, and management and marketing practices/services are important factors that must be taken into account when preparing the practice for the future. The problem that arises from this is the lack of skills among graduates and veterinarians in management and business. While corporate culture models are a foundation for large companies, the veterinary profession, especially on a small scale, lacks these fundamental structural elements.

The role of ecological and environmental approach in shaping the architectural environment for preschool education

The article considers the role of ecological and environmental approach in designing the architectural environment for preschool education based on the values of human interaction with the environment. Studying the specifics of designing the architectural environment for preschool education within the framework of the ecological and environmental approach identifies methods of the external space formation focused on children’s playing and providing educational features. The article addresses the specifics of playgrounds formation as the fundamental structural elements of the preschool institution territory for children of each age group taking into account the preschool environmental education. It identifies a range of special features of the building internal space design within the framework of environmental approach. Possible directions are identified for further development of the structural elements of the architectural environment for preschool education taking into account the improvement of efficiency of the environmental education.

Conserved buried water molecules enable the β-trefoil architecture.

Available high-resolution crystal structures for the family of β-trefoil proteins in the structural databank were queried for buried waters. Such waters were classified as either: (a) unique to a particular domain, family, or superfamily or (b) conserved among all β-trefoil folds. Three buried waters conserved among all β-trefoil folds were identified. These waters are related by the threefold rotational pseudosymmetry characteristic of this protein architecture (representing three instances of an identical structural environment within each repeating trefoil-fold motif). The structural properties of this buried water are remarkable and include: residing in a cavity space no larger than a single water molecule, exhibiting a positional uncertainty (i.e., normalized B-factor) substantially lower than the average Cα atom, providing essentially ideal H-bonding geometry with three solvent-inaccessible main chain groups, simultaneously serving as a bridging H-bond for three different β-strands at a point of secondary structure divergence, and orienting conserved hydrophobic side chains to form a nascent core-packing group. Other published work supports an interpretation that these interactions are key to the formation of an efficient folding nucleus and folded thermostability. The fundamental threefold symmetric structural element of the β-trefoil fold is therefore, surprisingly, a buried water molecule.