Composite Theory Research Articles

The Issue of Diachronic Composition in Aristotelian Hylomorphism

Abstract One of the many puzzles in Aristotelian hylomorphism is this: What happens to matter when it comes to be enformed? Interpreters ascribe to Aristotle different theories of diachronic composition. Some of them assume that he endorses a view that contemporary metaphysicians label as ‘preservationism’: matter survives unchanged in the hylomorphic whole. Others take it that he accepts what nowadays is tagged as ‘annihilationism’: matter is annihilated and replaced by a new object, the one created by the union of matter and form. And yet others argue that he maintains that matter survives in the hylomorphic whole but it undergoes some significant changes, a thesis which, in modern metaphysical parlance, is labelled as ‘alterationism’. This paper does four things. First, it shows that none of these approaches to the issue at hand is satisfactory. Second, it examines some key passages in Physics I 7 and Generation and Corruption I 1-5 where Aristotle is often assumed to maintain incompatible views about coming to be. Third, it argues that there is no incompatibility between the positions presented in these texts. Finally, it shows that this same textual evidence sheds light on Aristotle’s views on what happens to matter when it comes to be enformed. He actually adopts different theories of diachronic composition for different hylomorphic wholes. He applies alterationism to non-substances and annihilationism to substances.

Towards linking histological changes to liver viscoelasticity: a hybrid analytical-computational micromechanics approach.

Motivated by elastography that utilizes tissue mechanical properties as biomarkers for liver disease, with the eventual objective of quantitatively linking histopathology and bulk mechanical properties, we develop a micromechanical modeling approach to capture the effects of fat and collagen deposition in the liver. Specifically, we utilize computational homogenization to convert the microstructural changes in hepatic lobule to the effective viscoelastic modulus of the liver tissue, i.e., predict the bulk material properties by analyzing the deformation of repeating unit cell. The lipid and collagen deposition is simulated with the help of ad hoc algorithms informed by histological observations. Collagen deposition is directly included in the computational model, while composite material theory is used to convert fat content to the microscopic mechanical properties, which in turn is included in the computational model. The results illustrate the model's ability to capture the effect of both fat and collagen deposition on the viscoelastic moduli and represents a step towards linking histopathological changes in the liver to its bulk mechanical properties, which can eventually provide insights for accurate diagnosis with elastography.&#xD.

Using Community Composition and Successional Theory to Guide Site-Specific Coral Reef Management.

High spatial or temporal variability in community composition makes it challenging for natural resource managers to predict ecosystem trajectories at scales relevant to management. This is commonly the case in nearshore marine environments, where the frequency and intensity of disturbance events vary at the sub-kilometer to meter scale, creating a patchwork of successional stages within a single ecosystem. The successional stage of a community impacts its stability, recovery potential, and trajectory over time in predictable ways. Here we demonstrate the value of successional theory for interpreting fine-scale community heterogeneity using Hawaiian coral reefs as a case study. We tracked benthic community dynamics on 36 forereefs over a 6-year period (2017-2023) that captures impacts from high surf events, a marine heatwave, and unprecedented shifts in human behavior due to the COVID-19 pandemic. We document high spatial variation in benthic community composition that was only partially explained by island and environmental regime. Through hierarchical clustering, we identify three distinct community types that appear to represent different successional stages of reef development. Reefs belonging to the same community type exhibited similar rates of change in coral cover and structural complexity over time, more so than reefs located on the same island. Importantly, communities that were indicative of early succession (low coral cover reefs dominated by stress-tolerant corals) were most likely to experience an increase in coral cover over time, while later-stage successional communities were more likely to experience coral decline. Our findings highlight the influence of life history and successional stage on community trajectories. Accounting for these factors, not simply overall coral cover, is essential for designing effective management interventions. Site-specific management that accounts for a community's unique composition and history of disturbance is needed to effectively conserve these important ecosystems.

Research progress of bitumen bee structure based on atomic force microscopy: a literature review

ABSTRACT This review is focused on the bee structure observed by atomic force microscopy (AFM). For more than 20 years, the chemical origin and formation mechanism of the bee structure have been studied with the aid of AFM, resulting in numerous perspectives and controversies. Specifically, two dominant views dominate the debate on the chemical origin of bee structures. Some scholars tend to believe that the chemical composition of the bee structure is highly related to wax, while others consider that it is related to asphaltenes. In recent years, it has been acknowledged that the bee structure solely pertains to the microstructure on the surface of bitumen rather than its internal structure. The formation mechanism of the bee structure is elucidated by introducing the surface wrinkling theory of multilayer composites from the field of elastic-viscoelastic material. Based on the investigation of articles, this review concludes that the bee structure is more likely the wax crystallisation and surface wrinkling, and there exist certain specific correlations between the morphology of bee structures and macroscopic properties of bitumen. Furthermore, it is recommended that the bitumen research community adopt a standardised and simplified sample preparation procedure to enhance experimental comparability.

An Analytical Method for Determining the Stress–Strain State of a Subgrade with Combined Reinforcement

This article presents the fundamentals of an analytical method for determining the stress–strain state of a railway subgrade reinforced with geosynthetic material. The reinforcement described is a combined system where the geosynthetic material forms an open shell containing a layer of compacted crushed stone. The overall stress–strain state is proposed to be viewed as a superposition of two states of the subgrade. The stresses and displacements in the first state refer to the unreinforced subgrade (matrix), while the stress–strain state of the reinforcement element is determined using analytical constructs from composite theory. The dependencies of the overall stress–strain state are applied in a numerical analysis, which confirms the positive effect of reduced subgrade deformations. A small-scale experimental model further validates the accuracy of the analytical approach.

A historical overview on static and dynamic analyses of sandwich or partially composite beams and plates

This paper gives a brief overview of the static and the dynamic analyses of sandwich beams and sandwich plates composed of two elastic layers connected by a soft core. We show the strict correspondence between the sandwich beam, sandwich plate, and the analogous composite beam and composite plate problem with partial interaction. The beam problem is governed by a sixth-order differential equation in space for the deflection, whereas the plate problem is governed by a tri-Laplacian equation for the deflection, as first shown by Hoff in 1950 for symmetrical three-layer component (sandwich plate or composite plate theory with partial interaction). It is shown herein that the tri-Laplacian partial differential equation is also valid for general unsymmetrical sandwich plate or partially composite plate. In the limit cases, i.e., for non-composite action and for full-composite action, the beam model reduces into the Euler–Bernoulli beam model and the plate model into the Kirchhoff–Love model. Boundary layer phenomena may be predominant in the asymptotic stiff problem. The nonlocal bending moment–curvature of the sandwich beam (or composite beam with partial interaction) is analysed, and extended to a nonlocal Marcus bending moment–curvature for the composite plate theory. The consistency of the tri-Laplacian plate theory is commented, regarding the bi-Laplacian Reissner sandwich plate theory, which neglects the bending stiffnesses of each face layer. The paper finally presents results for the static bending and vibrations of sandwich beams and plates on simply supported boundary conditions, with a discussion on asymptotic limit cases.

Developing a stochastic linear elastic material model and composite laminate theory including failures, using the fiber bundle–based approach—Part II: Stochastic composite laminate theory

Using the fiber bundle cells (FBCs)-based stochastic material model developed in the first part of this paper, we derived a stochastic version of the classical composite laminate theory (SCLT) for controlled multiaxial deformation, where the strength parameters are stochastic variables. This model (SCLT) enables to describe both the deformation and the damage processes in each lamina up to the ultimate failure. By discussing some examples of simpler tensile load, we demonstrate the applicability of the results.

Study on the flexural load bearing performance of nail-laminated I-beams

ABSTRACT Using nail fastening technology to produce engineered wood by optimizing the combination of solid wood laminates is an effective means to optimize material utilization and reduce manufacturing complexity. This study explored the reliability of nail fastening technology in wood I-beam and analyzed that the connection method between the flanges and webs impacts the bending performance of the I-beam. The results showed that the connection method between the flanges and webs had important influence on the bending performance of the I-beam. The I-beams connected with nails and adhesive had better performance compared to those connected only with nails. Nail and adhesive combination laminated I-beams had a 159.85% and 495.84% increase in ultimate load and initial stiffness, respectively, compared to nail-laminated I-beams. The type of nail was an important factor to the bending performance of nail-laminated I-beams. Compared to round steel nails, self-tapping screws with stronger holding power were more suitable for the construction of I-beams. Installing stiffening ribs at the supports and loading points on both sides of the web enhanced the lateral stability and load-bearing capacity of the I-beams. The ultimate load and initial stiffness of I-beams with stiffening ribs increased by 28.26% and 5.74%, respectively, than the ones without stiffening ribs. The model established based on composite material mechanics theory could accurately predict the ultimate load capacity of self-tapping screw and adhesive combination laminated I-beams.

Developing a stochastic linear elastic material model and composite laminate theory including failures, using the fiber bundle–based approach—Part I: Stochastic Linear Elastic Material Model

This paper presents a novel theoretical statistical material model, which is a kind of extension of the usual 3D Hooke’s law and can take into account the damage process up to the final failure as well. This material model can provide the stress response also together with the damages to multiaxial short time alternating strain loads. It was developed by utilizing our earlier validated results of applying E-bundles for modelling stress-strain curve of different types of fibrous materials and fibre-reinforced composite sheets subjected to simple (uniaxial) mechanical loads. Based on the fiber bundle cells (FBC) theory, we introduced the so-called memory reliability functions to take into account the different changing strain loads including both the monotone, the pulsating and the alternating modes. We proved that the duplex compressive–tensile memory reliability function is the product of the compressive and the tensile memory reliability functions. Utilizing the generalized Hooke’s law and the memory reliability functions, we developed a stochastic linear elastic material law that also represents the damage and failure processes with normal and shear strain loads. This made it possible to calculate the expected value as the variance of the stress response process and determine its confidence interval at any strain load.

Dielectric Hybrid Optimization Model Based on Crack Damage in Semi-Rigid Base Course

To accurately predict the relative permittivity of cement-stabilized base materials, a study on the dielectric mixing model for cracked base materials was conducted. Based on the electromagnetic mixing theory of multiphase composites, a comprehensive dielectric mixing model of cement-stabilized base materials was derived. The volume ratios and relative permittivity values of the specimen constituents in different cracking states of the cement-stabilized base were determined using industrial CT and a Percometer relative permittivity meter, with comprehensive consideration given to the effects of different initial porosities and crack widths on the dielectric properties. Based on the volumetric and dielectric properties of the base material specimens in both intact and cracked states, as well as the error analysis between the predicted and measured values of the relative permittivity constant, the u-optimal solution of the dielectric mixing model for cement-stabilized base material was determined to be 1. Consequently, an optimization dielectric mixing model for semi-rigid base course materials in a cracked state was developed. The optimization model proposed is suitable for predicting the dielectric properties of cement-stabilized base material with crack widths generally greater than 3 mm during the service life of semi-rigid base course in engineering practice.

Adaptive RBF iterative learning tracking control of multi-degree-of-freedom manipulators

Abstract Targeting on the issue of poor dynamic performance of multi-degree-of-freedom manipulator system under disturbance environment and model parameter uncertainty, this paper designs an adaptive iterative learning tracking control method utilizing a radial basis function (RBF) neural network observer, aiming at realizing stable control and disturbance suppression of closed-loop system. The controller consists of the proportional-differential term based on the backstepping method, the sign function robust term of adaptive sliding mode, and the disturbance observation term of the RBF neural network. The sign function robust term compensates for the repetitive disturbance of the system, and the RBF observer compensates for the non-repetitive disturbance of the system. Under the premise of ensuring the normal functioning of the control system, the sliding mode parameter is updated in the iterative domain, and the RBF network weight parameter is updated in the time domain to enhance the system’s robustness. Simultaneously, the stability of the closed-loop system within the iterative domain and the convergence of the tracking error are demonstrated using the Lyapunov composite energy theory. Finally, the proposed control method’s efficacy and robustness are validated through simulation and experiment.

Parenting behaviour and student discipline in public boarding secondary schools in Western region of Kenya

Discipline in schools is an issue that especially concerns educators, parents, and other stakeholders. In an environment that lacks order and discipline, it is impossible for students to learn effectively. Thus, order and discipline are indispensable for achieving positive educational results. The family assumes a pivotal role in shaping the early years of an individual. The purpose of this research was to investigate the influence of parenting behaviour on student discipline in public boarding secondary schools in Western region of Kenya. Family composition and structural-functionalism theories served as guiding principles for the research. The investigation was conducted using an ex post facto design. The study's target population consisted of 5583 class teachers and 369 deputy principals (administrators-in-charge) from 369 public boarding secondary institutions. The sample included 123 deputy Principals and 558 class teachers from the 123 randomly selected schools. Simple random sampling was used to select 558 class teachers while purposive sampling was used to select 123 deputy Principals. For the purpose of data collection from the participants, a questionnaire and an interview schedule were employed. The assessment of the instruments' reliability was conducted using the test-retest method, results of the pilot study reveal that all scales were trustworthy because their reliability values were more than the required threshold of 0.7. Data was analyzed using frequency, percentages, weighted averages, correlations and multi-regression analysis. The study concluded that parenting behavior influence the discipline of students in public secondary schools. Therefore, it was recommended that school management boards should organize for the sensitization meetings on effective parenting behaviour, this will enable curb indiscipline among students.

Mechanism of instability in non-uniform dusty channel flow

Particles in pressure-driven channel flow are often inhomogeneously distributed. Two modes of low-Reynolds-number instability, absent in Poiseuille flow of clean fluid, are created by inhomogeneous particle loading, and their mechanism is worked out here. Two distinct classes of behaviour are seen: when the critical layer of the dominant perturbation overlaps with variations in particle concentration, the new instabilities arise, which we term overlap modes. But when the layers are distinct, only the traditional Tollmien–Schlichting mode of instability occurs. We derive the dominant critical-layer balance equations in this flow along the lines done classically for clean fluid. These reveal how concentration variations within the critical layer cause the two particle-driven instabilities. As a result of these variations, disturbance kinetic energy production is qualitatively and majorly altered. Surprisingly, the two overlap modes, although completely different in the symmetry of the eigenstructure and regime of exponential growth, show practically identical energy budgets, highlighting the relevance of variations within the critical layer. The wall layer is shown to be unimportant. We derive a minimal composite theory comprising all terms in the complete equation which are dominant somewhere in the flow, and show that it contains the essential physics. When particles are infinitely dense relative to the fluid, the volume fraction is negligible. But for finite density ratios, the volume fraction of particles causes a profile of effective viscosity. This is shown to be uniformly stabilizing in the present flow. Gravity is neglected here, and will be important to study in the future. So will the transient growth of perturbations due to non-normality of the stability operator, in a quest for the mechanism of transition to turbulence.

Crack monitoring and repair model of SMA composite material based on strain transfer

In the process of using composite materials, crack damage is unavoidable. These cracks may cause a decrease in the structural performance of the material and may even pose a threat to the safety of the entire structure. In this paper, the shape memory alloy (SMA) is embedded into the composite material, and the strain transfer effect of the interface layer is considered. The crack monitoring and repair model of SMA composite material based on strain transfer are established using SMA resistance-sensing characteristics and SMA constitutive model. Based on this monitoring and repair model, the crack monitoring behavior of SMA under different initial states and temperature conditions is discussed, and the crack repair behavior of SMA under specific initial states and temperature conditions is also discussed. The research results show that the change in SMA resistance and the strain of the composite material crack are linearly segmented, and as the temperature increases, the composite material crack is gradually repaired. This study can provide theoretical guidance for the further engineering application of SMA composite material crack monitoring and repair theory.

Investigating on the tribological behavior of binderless WC matrix composite

The purpose of this study was to investigate the dry friction and wear behavior of WC-4.3 wt%MgO-2wt.%ZrO2 (WM2Z) composite. WM2Z composite prepared by high-energy ball milling and spark plasma sintering (SPS) technology exhibited excellent comprehensive mechanical properties and dense microstructure. Dry friction test results indicated that the increase of sliding speed will lead to the decrease of friction coefficient, while at the same sliding speed, the extension of sliding time has no significant effect on the friction coefficient. The wear volume increased proportionally with the sliding time, while the wear rate stabilized after reaching a certain duration. The wear mechanism was mainly slight abrasive wear. Additionally, some oxidation occurred on both the WM2Z composite and the Si3N4 ball during friction, forming an oxide film that contributed to the reduction of the friction coefficient. The novelty of this study lies in the first systematic investigation of the effects of sliding speed and time on the wear performance of WM2Z composite, and the revelation that in high-speed sliding environments, even with shorter sliding times, the material experiences faster wear. This discovery emphasizes the important role of sliding speed in the wear process and provides new insights into understanding the wear mechanism of materials in practical applications. This study not only enriches the friction and wear theory of binderless WC matrix composites, but also provides important experimental data and theoretical support for the design and application of related materials, laying a solid foundation for wear resistance optimization and industrial applications.

Compositionality and Observational Refinement for Linearizability with Crashes

Crash-safety is an important property of real systems, as the main functionality of some systems is resilience to crashes. Toward a compositional verification approach for crash-safety under full-system crashes, one observes that crashes propagate instantaneously to all components across all levels of abstraction, even to unspecified components, hindering compositionality. Furthermore, in the presence of concurrency, a correctness criterion that addresses both crashes and concurrency proves necessary. For this, several adaptations of linearizability have been suggested, each featuring different trade-offs between complexity and expressiveness. The recently proposed compositional linearizability framework shows that to achieve compositionality with linearizability, both a locality and observational refinement property are necessary. Despite that, no linearizability criterion with crashes has been proven to support an observational refinement property. In this paper, we define a compositional model of concurrent computation with full-system crashes. We use this model to develop a compositional theory of linearizability with crashes, which reveals a criterion, crash-aware linearizability , as its inherent notion of linearizability and supports both locality and observational refinement. We then show that strict linearizability and durable linearizability factor through crash-aware linearizability as two different ways of translating between concurrent computation with and without crashes, enabling simple proofs of locality and observational refinement for a generalization of these two criteria. Then, we show how the theory can be connected with a program logic for durable and crash-aware linearizability, which gives the first program logic that verifies a form of linearizability with crashes. We showcase the advantages of compositionality by verifying a library facilitating programming persistent data structures and a fragment of a transactional interface for a file system.

Non-termination Proving at Scale

Program termination is a classic non-safety property whose falsification cannot in general be witnessed by a finite trace. This makes testing for non-termination challenging, and also a natural target for symbolic proof. Several works in the literature apply non-termination proving to small, self-contained benchmarks, but it has not been developed for large, real-world projects; as such, despite its allure, non-termination proving has had limited practical impact. We develop a compositional theory for non-termination proving, paving the way for its scalable application to large codebases. Discovering non-termination is an under-approximate problem, and we present UNTer, a sound and complete under-approximate logic for proving non-termination. We then extend UNTer with separation logic and develop UNTer SL for heap-manipulating programs, yielding a compositional proof method amenable to automation via under-approximation and bi-abduction. We extend the Pulse analyser from Meta and develop Pulse ∞ , an automated, compositional prover for non-termination based on UNTer SL . We have run Pulse ∞ on large codebases and libraries, each comprising hundreds of thousands of lines of code, including OpenSSL, libxml2, libxpm and CryptoPP; it discovered several previously-unknown non-termination bugs and have reported them to developers of these libraries.

Characterisation and simulation of a general ventilation filter based on a double porosity approach

The air filters installed in ventilation systems are designed for collecting dust and particles. These filters usually consist in folded paper or textile, arranged either as a flat slab or in a V-shape frame. Some of them may also contain activated carbon in order to remove molecular compounds. Experimental results show that they can significantly attenuate the upstream sound sources such as fans or other regenerated noise. Though, these acoustic properties are not strictly speaking designed and often result from the tailored filtering capacities. The present work proposes a three-stage methodology to design and optimize the acoustic performance of these filters. The first stage is the characterization of the intrinsic acoustic parameters of the paper or textile. The second stage consists in the validation of these parameters regarding sound attenuation as measured in impedance tube. This includes analytical and finite element computations to correctly account for the mounting conditions of the specimen in the impedance tube. The final stage consists in predicting the sound attenuation measured on the full-size filter, set in shape using the porous composite material theory. The obtained results provide a satisfactory correspondence allowing for an accurate design at an early stage of the project.

Variation of the Passive Film on Compositionally Concentrated Dual-Phase Al0.3Cr0.5Fe2Mn0.25Mo0.15Ni1.5Ti0.3 and Implications for Corrosion

The passive film on a dual-phase Al0.3Cr0.5Fe2Mn0.25Mo0.15Ni1.5Ti0.3 FCC + Heusler (L21) compositionally concentrated alloy formed during extended exposure to an applied potential in the passive range in dilute chloride solution was characterized. Each phase, with its own distinct composition of passivating elements, formed unique passive films separated by a heterophase interface. High-resolution, surface sensitive characterization enabled chemical analysis of the passive film formed over individual phases. The film formed over the L21 phase had a higher concentration of Al, Ni, and Ti, while the film formed over FCC phase was of similar thickness but contained comparatively higher Cr, Fe, and Mo concentrations, consistent with the differences in bulk microstructure composition. The passive film was continuous across phase boundaries and the distribution of passivating elements (Al, Cr, and Ti) indicated both phases were independently passivated. Spatially resolved analysis of the surface chemistry of the dual-phase CCA revealed that the cation with the highest composition in passive film formed on the FCC phase was Cr (52.4 at. pct) and for the L21 phase was Ti (53.1 at. pct) despite the bulk concentration of each element being below 20 at. pct in their respective phases. Al, Cr, and Ti were enriched in both phases within the passive film relative to their respective bulk compositions. In parallel studies, single-phase alloys with compositions representative of the FCC and L21 phases were synthesized to evaluate the corrosion behavior of each phase in isolation. The corrosion behavior of the dual-phase alloy showed passivity evidenced by a pitting potential of 0.615 VSCE in 0.01 M NaCl. The pitting potential and other electrochemical parameters suggested a combination of behaviors of both single-phase samples, suggesting that the global corrosion behavior may be represented by a composite theory applied to phases, their area fractions, and interphase length. However, the interphase in the dual-phase CCA was a local corrosion initiation site and may limit localized corrosion protectiveness. The alloy design implications for optimization of second phase structure and morphology are discussed.

Defining the boundaries of the meaning of ornamental compositions in the art of the Pazyryk culture

The article is devoted to the analysis of the semiotic field of the term "ornamental composition" in the context of definitions of ornament and composition in the art of the Pazyryk culture and its historiography. The subject of the study is ornamental compositions from elite burials of the Pazyryk culture of different periods of its development – the early Second Bashadar kurgan and the Tuekta burial ground and the late Pazyryk burial ground. In addition, the paper examines the specifics of the use of the terms "composition" and "ornament" in order to highlight the history of their meanings, as well as analyzes certain provisions of theoretical works on the study of the theory of composition and ornament. The purpose of the study is to identify the components of the semantic field of an ornamental composition related to the field of interaction of the composition with the viewer, and not to the field of meaning of specific figurative images. The article proposes using the method of formal analysis in combination with some provisions of the Gestalt approach described in the works of E. Gombrich and R. Arnheim to analyze a series of ornamental compositions with and without figurative images in the art of the Pazyryk culture. The scientific novelty of the study is predetermined by the absence in the Russian historiography of works describing the specifics of the meaning of ornamental composition in the context of visual perception in the art of the Pazyryk culture. The researchers note that the significance of ornaments in Pazyryk art could be related to the meaning of multi-figure compositions (when zoomorphic images are included in the ornament) and reflect the worldview of the bearers of the Pazyryk culture, or the types of symmetry used in the construction of ornaments could reflect the social structure of society. However, in both of these trends, the analysis of an ornamental composition without figurative images remains outside the scope as a structural and semantic, integral work of art interacting with the viewer. As a result of the research, the assumption is put forward that it is possible to designate a single semantic field for ornamental and multi-figure compositions in Pazyryk art. Clarifying and expanding the scope of the ornamental composition allows us to identify a single specificity of interaction with the viewer of both figurative and non-figurative images of Pazyryk art, to emphasize the game element in the nature of culture.