Theory Of Structural Transformations Research Articles

A Reappraisal of Albert Aftalion’s Theory of Structural Transformation in an Era of Decarbonization

AbstractDecarbonization is a momentous challenge for capitalism and makes one to ask which changes in its morphology may be necessary to achieve that objective. The contribution by the French economist Albert Aftalion (1874–1956), with its emphasis on intermediate levels of aggregation (the “meso“ approach), the differentiated time profiles of economic actoivities, and their differential speeds of reaction to dynamic impulses, provides an invaluable heuristic for conceptualizing the structural transformations required by transition to a low energy regime. Aftalion’s analysis of industrial capitalism emphasizes that structural changes occur along multiple co-existing time horizons. This provides tools to analyze the time constraints on the sequencing of structural changes for different sectors on a decarbonization trajectory without neglecting the strict time requirements for implementing effective climate change mitigation. This interplay of time horizons is central to decarbonization, and it will require a new balance between the invisible hand of markets and the visible hand of states and other public bodies. Moreover, Aftalion’s emphasis on material constraints offers a novel approach to conceptualizing the importance of intermediate levels of aggregation in economic theory, thereby offering a new basis for sectoral policymaking and a fundamental challenge to institutionalist accounts of the morphology of capitalism.

From Suspicion and Accommodation to Structural Transformation: Enhanced Scholarship through Enhanced Community-University Relations

While substantial efforts are being made in some universities to democratize the production, ownership, and use of knowledge through partnership with the community, significant barriers to community-university partnership persist, maintained through inequitable research relations, reductionist definitions of knowledge, and disincentives for faculty who are interested in community-based scholarship. The perseverance of this disconnect, we argue, is indicative of an existential aversion to community that lies deep within the psyche of the university. We liken the aversion to that of a disgust response, a social response that creates distance from that which is perceived to be dangerous, which in this case serves to preserve the university’s privileged status as knowledge producer. In this paper we bring forward arguments for the importance of community-engaged scholarship to the university’s civic role, to the pursuit of knowledge, and to the principles of democracy. We highlight promising advances in how some universities are accommodating community partnership within their definitions of scholarship and academic production, and, drawing upon Gordon’s theory of structural transformation and Bourdieu’s conceptualization of agency and habitus, we consider how such changes might be brought about at a deeper, structural level within the university.

Scale invariance of plastic deformation of the planar and crystal subsystems of solids under superplastic conditions

The theory of structural transformations in the planar sybsystem (surface layers and internal interfaces) of solids under plastic deformation is developed. The theory is based on a consideration for local curvature of the crystal lattice, with new structural states arising in its interstices, responsible for plastic distortion. To satisfy the superplastic condition, such high-rate mechanisms should develop in both planar and 3D crystal subsystems. In a translation-invariant crystal, this condition is met by concentration fluctuations. The multiscale criterion of superplasticity is formulated based on the scale invariance of plastic deformation of the planar and crystal subsystems in a deformable solid. Beyond the criterion, superplasticity passes to the creep mode with restricted plasticity of the material.

Thermodynamic Model Formulations for Inhomogeneous Solids with Application to Non-isothermal Phase Field Modelling

Abstract The purpose of the current work is the comparison of thermodynamic model formulations for chemically and structurally inhomogeneous solids at finite deformation based on “standard” non-equilibrium thermodynamics [SNET: e. g. S. de Groot and P. Mazur, Non-equilibrium Thermodynamics, North Holland, 1962] and the general equation for non-equilibrium reversible–irreversible coupling (GENERIC) [H. C. Öttinger, Beyond Equilibrium Thermodynamics, Wiley Interscience, 2005]. In the process, non-isothermal generalizations of standard isothermal conservative [e. g. J. W. Cahn and J. E. Hilliard, Free energy of a non-uniform system. I. Interfacial energy. J. Chem. Phys. 28 (1958), 258–267] and non-conservative [e. g. S. M. Allen and J. W. Cahn, A macroscopic theory for antiphase boundary motion and its application to antiphase domain coarsening. Acta Metall. 27 (1979), 1085–1095; A. G. Khachaturyan, Theory of Structural Transformations in Solids, Wiley, New York, 1983] diffuse interface or “phase-field” models [e. g. P. C. Hohenberg and B. I. Halperin, Theory of dynamic critical phenomena, Rev. Modern Phys. 49 (1977), 435–479; N. Provatas and K. Elder, Phase Field Methods in Material Science and Engineering, Wiley-VCH, 2010.] for solids are obtained. The current treatment is consistent with, and includes, previous works [e. g. O. Penrose and P. C. Fife, Thermodynamically consistent models of phase-field type for the kinetics of phase transitions, Phys. D 43 (1990), 44–62; O. Penrose and P. C. Fife, On the relation between the standard phase-field model and a “thermodynamically consistent” phase-field model. Phys. D 69 (1993), 107–113] on non-isothermal systems as a special case. In the context of no-flux boundary conditions, the SNET- and GENERIC-based approaches are shown to be completely consistent with each other and result in equivalent temperature evolution relations.

Theory of structural transformation in lithiated amorphous silicon.

Determining structural transformations in amorphous solids is challenging due to the paucity of structural signatures. The effect of the transitions on the properties of the solid can be significant and important for applications. Moreover, such transitions may not be discernible in the behavior of the total energy or the volume of the solid as a function of the variables that identify its phases. These issues arise in the context of lithiation of amorphous silicon (a-Si), a promising anode material for high-energy density batteries based on lithium ions. Recent experiments suggest the surprising result that the lithiation of a-Si is a two-phase process. Here, we present first-principles calculations of the structure of a-Si at different lithiation levels. Through a detailed analysis of the short and medium-range properties of the amorphous network, using Voronoi-Delaunay methods and ring statistics, we show that a-LixSi has a fundamentally different structure below and above a lithiation level corresponding to x ∼ 2.

The Khachaturyan theory of elastic inclusions: Recollections and results

In keeping with the assignment, this paper has two parts. The first is a personal recollection of my interactions with Professor Armen Khachaturyan since he first visited Berkeley in the 1970s. The second part is a review of the Khachaturyan formulation of the theory of elastic inclusions, with emphasis on results found since his classic monograph on the Theory of Structural Transformations in Solids [Wiley, New York, 1983]. The focus here is on the shapes and habits of coherent inclusions. The basic theory is presented, briefly, to exhibit Khachaturyan's results for the strain and energy within a coherent inclusion and show that the elastic energy is minimal for a thin-plate morphology with a definite habit. The preferred habit of the thin-plate inclusion is then discussed and computed for inclusions with dyadic strain (including the dislocation loop) and coherent inclusions with orthorhombic or simpler symmetry. This is followed by a discussion of the evolution of precipitate shape during coarsening, including the theory of the spontaneous splitting of coarsening precipitates and the development of octahedral or tetrahedral shapes.

On the theory of structural transformations in polar colloids

Structural transformations in the ensemble of particles with permanent intrinsic dipole moment are theoretically studied. In addition to dipole-dipole component, interparticle potential includes central attractive interaction. Such systems belong to ferrocolloids (ferrofluids) whose particle central molecular interaction is not completely screened by the protective surface layers, to polar molecular liquids, and other similar media. Main attention is focused on the analysis of chain-dense globule transitions in particle ensembles. The obtained results demonstrate that even weak central interaction between particles can induce such a transition. The performed studies explain why, in most of the known computer experiments with polar particles, the formation of dense bulk phases is observed only at the presence of central interparticle attraction and only dipole-dipole interaction results in the formation of linear chain structures, but not bulk phases.

Phase-field model for ferromagnetic shape-memory alloys

A computational model is developed to predict the ferroelastic and ferromagnetic domain structures in ferromagnetic shape-memory alloys by combining the phase-field approach, micromagnetics and the microelasticity theory of Khachaturyan [Theory of Structural Transformations in Solid (Wiley, New York, 1983)]. As an example, the NiMnGa ferromagnetic shape-memory alloy is considered. Both the magnetic domain structures and martensite microstructures are studied. The emphasis is on the overall strain response and associated evolution of both magnetic domain structure and martensite microstructure under an applied magnetic field with different initial conditions. The results are compared with existing experiment measurements and observations.

Theory of structural transformations in ferrofluids: chains and "gas-liquid" phase transitions.

We consider a ferrofluid consisting of identical spherical particles with a permanent magnetic moment. Under the assumption that linear flexible chains can appear in the ferrofluid, we estimate the distribution function of the number of particles inside the chain. The analysis is done and simple expressions for the size distribution function are obtained in asymptotics of a strong magnetic interaction between the particles inside one chain. We studied the influence of the linear chains on conditions and scenarios of bulk "gas-liquid" phase transition in the ensemble of the particles under an infinitely strong magnetic field. In order to study the influence of the chains on bulk "gas-liquid" phase transition in the ensemble of the particles, their chemical potential mu is calculated in the model of separate interacting particles as well as in the model with chains, taking into account the interaction between them. When the temperature is low enough, van der Waals loops appear on the plots of mu versus volume concentration phi of the particles in the first model; function mu(phi) increases monotonically in the second model for all examined temperatures. This means that the condensation "gas-liquid" phase transition can take place in the model of individual particles; however, formation of the chains in real ferrofluids prevents the appearance of this transition.

Internal oxidation of CuFe—II. The morphology of oxide inclusions from the minimization of elastic misfit energy

Two types of iron-oxides, both with cubic spinel structure occur simultaneously during internal oxidation of CuFe and form plates on different habit planes of the matrix. Khachaturyan's theory [ Theory of Structural Transformations in Solids. Wiley, New York (1983)] for the elastic energy of coherent inclusions was applied to the present case and both habit planes were predicted correctly on the grounds of the orientation relations between the crystal lattices of matrix and precipitates. Moreover, the effect of uncertainties in the numerical values of misfit strain and elastic constants was explored and the result was found to be stable within reasonable variations of these parameters. This shows that the morphology of iron oxides in internally oxidized CuFe is mainly due to elastic misfit strain.

Relational dynamics of charismatic organization: The complementarity of love and power

Abstract: This paper outlines a new theory of structural transformation in charismatic systems by postulating a complementary relationship between love and power. Radical reorganization of social organization, the function of charismatic systems, requires mobilizing and realigning enormous amounts of social energy. The source of this social energy is love. When patterned as communion, love fuses the group into an undifferentiated whole and releases the social energy previously locked up as institutionalized structure. Released from structure or form, however, social energy is highly volatile and produces immense pressures towards instability. Counterbalancing the pressure from communion, a strong, collective order of power functions to harness and align the energy, thereby promoting group stability and enhancing the prospects for structural transformation. Data from a national study of sixty urban communal organizations are used to ground key aspects of the theory.

Theory of structural transformations in flowing systems

The process of structural transformations in flowing systems is described on the basis of joint examination of the flow and mutual-transformation kinetics of kinetic-molecular units.

From Suspicion and Accommodation to Structural Transformation: Enhanced Scholarship through Enhanced Community-University Relations

While substantial efforts are being made in some universities to democratize the production, ownership, and use of knowledge through partnership with the community, significant barriers to community-university partnership persist, maintained through inequitable research relations, reductionist definitions of knowledge, and disincentives for faculty who are interested in community-based scholarship. The perseverance of this disconnect, we argue, is indicative of an existential aversion to community that lies deep within the psyche of the university. We liken the aversion to that of a disgust response, a social response that creates distance from that which is perceived to be dangerous, which in this case serves to preserve the university’s privileged status as knowledge producer. In this paper we bring forward arguments for the importance of community-engaged scholarship to the university’s civic role, to the pursuit of knowledge, and to the principles of democracy. We highlight promising advances in how some universities are accommodating community partnership within their definitions of scholarship and academic production, and, drawing upon Gordon’s theory of structural transformation and Bourdieu’s conceptualization of agency and habitus, we consider how such changes might be brought about at a deeper, structural level within the university.