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Ryszard Staroszczyk - One of the best experts on this subject based on the ideXlab platform.
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Stress and strain-rate formulations for fabric evolution in polar ice
Continuum Mechanics and Thermodynamics, 2003Co-Authors: Leslie Morland, Ryszard StaroszczykAbstract:Re-orientation of individual crystal glide planes, as isotropic surface ice is deformed during its passage to depth in an ice sheet, creates a fabric and associated anisotropy. We re-examine an orthotropic viscous Law which was developed to reflect the induced anisotropy arising from the mean rotation of crystal axes during deformation. This expresses the deviatoric stress, the stress formulation, in terms of the strain-rate, strain, and three structure tensors based on the principal stretch axes, and involves two fabric response coefficient functions which determine the strength of the anisotropy. A validity condition implicitly relates the two response functions, so the Model Law has only one independent fabric response function. A modified formulation is now presented in which the two fabric response coefficients are expressed as functions of different invariant arguments, and the validity condition becomes an explicit algebraic relation between the two functions. The response can therefore be described explicitly in terms of a single fabric response function. An analogous orthotropic viscous Law for the strain-rate, the strain-rate formulation, akin to the conventional “flow Law” for isotropic ice, expressed in terms of the deviatoric stresss, strain and the three structure tensors, is also constructed. Correlations with complete (idealised) uni-axial compression and shearing responses are made for the stress formulation, to determine the fabric response function which would yield these responses. Ice core samples taken from depth in an ice sheet reveal strong fabrics, shown by significant alignment of initially randomly distributed c-axes of individual crystals, and consequent substantial differences in shear viscosities in different planes. The macroscopic viscous Law for the shear stress proposed by Morland and Staroszczyk [1] was motivated by a simple picture of lattice rotation by basal slip in which the angle between individual crystal glide planes, material planes, and planes normal to principal axes of compression, decreases, and the angle between individual crystal glide planes and planes normal to principal axes of extension, increase. These three planes, with normals the principal stretch axes, are described as the principal stretch planes. The instantaneous viscous response at each stage of the deformation has reflexional symmetry in these planes; that is, the instantaneous viscous response is orthotropic with respect to the current principal stretch planes. It is further assumed that the directional strengths of the response depend only on the current deformation, which is an assumption that the generated fabric and subsequent response are independent of the deformation path, which is a questionable restriction. The orthotropic viscous Law is then a frame indifferent relation between deviatoric stress, strainrate, deformation, and the three structure tensors defined by the outer products of the three orthogonal unit vectors along the principal stretch axes. The simple Morland and Staroszczyk [1] Model, a stress formulation in which the deviatoric stress is expressed in terms of the other tensors, involved one set of tensor generators with one coefficient, described as a fabric response function. Subsequently, a set of equalities and inequalities on the instantaneous directional viscosities derived from the rotation concepts by Staroszczyk and Morland
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Strain-rate formulation of ice fabric evolution
Annals of Glaciology, 2003Co-Authors: Leslie Morland, Ryszard StaroszczykAbstract:AbstractReorientation of individual crystal-glide planes as isotropic surface ice is deformed during its passage to depth in an ice sheet, lattice rotation, creates a fabric and associated anisotropy. A simple macroscopic description is that these material glide planes are rotated towards planes normal to an axis of compression, and away from planes normal to an axis of extension, inducing an instantaneous orthotropic viscous response with reflexional symmetries in the planes orthogonal to the current principal stretch axes. An orthotropic viscous Law is presented for the strain rate expressed in terms of the deviatoric stress, the deformation, and three structure tensors based on the principal stretch axes. This anisotropic relation is expressed in terms of a single fabric response function in addition to the isotropic ice viscosity. The predicted responses in uniaxial compression and simple shear are determined. While the uniaxial response yields an explicit relation between the axial strain rate and stress, it is found that the shear response is governed by three, complicated, coupled relations between the shear strain rate and three deviatoricstress components. The new result derived here is the solution of this system: an explicit relation between the shear strain rate and shear stress. Correlation of these relations with idealized uniaxial and shear responses is then used to determine the required fabric function in the Model Law.
Steven L. Schwarcz - One of the best experts on this subject based on the ideXlab platform.
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A Model-Law Approach to Sovereign Debt Restructuring
2017Co-Authors: Steven L. SchwarczAbstract:Unresolved sovereign debt problems and disruptive litigation are hurting debtor nations and their citizens, as well as their creditors. A default can also pose a serious systemic threat to the international financial system. Yet the existing “contractual” approach to sovereign debt restructuring, including the use of so-called collective action clauses, is insufficient to solve the holdout problem; recent empirical research indeed shows a drastic rise in sovereign debt litigation by holdout creditors. And the political economy of treaty-making makes a multilateral “statutory” approach highly unlikely to succeed in the near future. This article, prepared at the invitation of the United Nations Commission on International Trade Law (UNCITRAL) for presentation at its 50th Anniversary Congress, shows why a Model-Law approach to sovereign debt restructuring should be realistic and effective. Nations and even subnational jurisdictions could individually enact a Model Law as their internal Law, and contracts governed by that Law would thereby become governed by the Model Law. Choice of Law thus gives a Model-Law approach a powerful multiplier effect. A Model-Law approach could also solve the problem of pari passu clauses and address the critical need for a financially troubled nation to obtain liquidity during its restructuring process. The article proposes a form of Sovereign Debt Restructuring Model Law, which has been vetted in discussions with leading experts worldwide and also embraces the Basic Principles on Sovereign Debt Restructuring Processes adopted by the United Nations General Assembly in 2015. At the very least, pursuing the Model Law in parallel to other approaches would help to develop norms for a sovereign debt restructuring legal framework that goes beyond mere contracting.
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Sovereign Debt Restructuring and English Governing Law
The Brooklyn Journal of Corporate Financial and Commercial Law, 2017Co-Authors: Steven L. SchwarczAbstract:Whether or not their fault, nations sometimes borrow at levels that become unsustainable. Until resolved, the resulting debt burden hurts not only those nations but also their citizens, their creditors, and — by posing serious systemic risks to the international financial system — the wider economic community. The existing contractual framework for restructuring sovereign debt is inadequate, often leaving little alternative between a bailout, which is costly and creates moral hazard, and a default, which raises the specter of financial contagion and chaos. Although global organizations, including the United Nations and the International Monetary Fund, have tried to strengthen the sovereign-debt-restructuring framework through treaties, such a multilateral legal approach is highly unlikely to succeed in the near future. This essay argues that a Model-Law approach should facilitate sovereign debt restructuring much more feasibly than a multilateral approach. Model Laws have long been used in cross-border Lawmaking, when treaties fail. Unlike a treaty, a Model Law does not require widespread acceptance for its implementation. In particular, if this essay’s Model Law were enacted into English Law, that alone would enable the fair and consensual restructuring of the immense stock — perhaps a quarter to a third or more of all sovereign debt contracts — of such contracts governed by that Law. And because it would achieve, by operation of Law, the equivalent of the ideal goal of including aggregate-voting collective action clauses in all sovereign debt contracts, such enactment should ensure the continuing legitimacy and attractiveness of English Law as the governing Law for future sovereign debt contracts. At the very least, however, this essay should serve to increase a Model-Law approach’s political feasibility by explaining the approach and its potential benefits and limitations. An incremental approach to developing norms, such as one developed through a Model Law, has strong precedent in the legal ordering of international relationships.
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A Model Law Approach to Restructuring Unsustainable Sovereign Debt
2015Co-Authors: Steven L. SchwarczAbstract:Unresolved sovereign debt problems are hurting debtor nations, their citizens and their creditors, and also can pose serious systemic threats to the international financial system. The existing contractual restructuring approach is insufficient to make sovereign debt sustainable. Although a more systematic legal resolution framework is needed, a formal multilateral approach, such as a treaty, is not currently politically viable. An informal Model-Law approach should be legally, politically and economically feasible. This informal approach would not require multilateral acceptance. Because most sovereign debt contracts are governed by either New York or English Law, it would be sufficient if one or both of those jurisdictions enacted a proposed Sovereign Debt Restructuring Model Law as their domestic Law.
Leslie Morland - One of the best experts on this subject based on the ideXlab platform.
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Stress and strain-rate formulations for fabric evolution in polar ice
Continuum Mechanics and Thermodynamics, 2003Co-Authors: Leslie Morland, Ryszard StaroszczykAbstract:Re-orientation of individual crystal glide planes, as isotropic surface ice is deformed during its passage to depth in an ice sheet, creates a fabric and associated anisotropy. We re-examine an orthotropic viscous Law which was developed to reflect the induced anisotropy arising from the mean rotation of crystal axes during deformation. This expresses the deviatoric stress, the stress formulation, in terms of the strain-rate, strain, and three structure tensors based on the principal stretch axes, and involves two fabric response coefficient functions which determine the strength of the anisotropy. A validity condition implicitly relates the two response functions, so the Model Law has only one independent fabric response function. A modified formulation is now presented in which the two fabric response coefficients are expressed as functions of different invariant arguments, and the validity condition becomes an explicit algebraic relation between the two functions. The response can therefore be described explicitly in terms of a single fabric response function. An analogous orthotropic viscous Law for the strain-rate, the strain-rate formulation, akin to the conventional “flow Law” for isotropic ice, expressed in terms of the deviatoric stresss, strain and the three structure tensors, is also constructed. Correlations with complete (idealised) uni-axial compression and shearing responses are made for the stress formulation, to determine the fabric response function which would yield these responses. Ice core samples taken from depth in an ice sheet reveal strong fabrics, shown by significant alignment of initially randomly distributed c-axes of individual crystals, and consequent substantial differences in shear viscosities in different planes. The macroscopic viscous Law for the shear stress proposed by Morland and Staroszczyk [1] was motivated by a simple picture of lattice rotation by basal slip in which the angle between individual crystal glide planes, material planes, and planes normal to principal axes of compression, decreases, and the angle between individual crystal glide planes and planes normal to principal axes of extension, increase. These three planes, with normals the principal stretch axes, are described as the principal stretch planes. The instantaneous viscous response at each stage of the deformation has reflexional symmetry in these planes; that is, the instantaneous viscous response is orthotropic with respect to the current principal stretch planes. It is further assumed that the directional strengths of the response depend only on the current deformation, which is an assumption that the generated fabric and subsequent response are independent of the deformation path, which is a questionable restriction. The orthotropic viscous Law is then a frame indifferent relation between deviatoric stress, strainrate, deformation, and the three structure tensors defined by the outer products of the three orthogonal unit vectors along the principal stretch axes. The simple Morland and Staroszczyk [1] Model, a stress formulation in which the deviatoric stress is expressed in terms of the other tensors, involved one set of tensor generators with one coefficient, described as a fabric response function. Subsequently, a set of equalities and inequalities on the instantaneous directional viscosities derived from the rotation concepts by Staroszczyk and Morland
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Strain-rate formulation of ice fabric evolution
Annals of Glaciology, 2003Co-Authors: Leslie Morland, Ryszard StaroszczykAbstract:AbstractReorientation of individual crystal-glide planes as isotropic surface ice is deformed during its passage to depth in an ice sheet, lattice rotation, creates a fabric and associated anisotropy. A simple macroscopic description is that these material glide planes are rotated towards planes normal to an axis of compression, and away from planes normal to an axis of extension, inducing an instantaneous orthotropic viscous response with reflexional symmetries in the planes orthogonal to the current principal stretch axes. An orthotropic viscous Law is presented for the strain rate expressed in terms of the deviatoric stress, the deformation, and three structure tensors based on the principal stretch axes. This anisotropic relation is expressed in terms of a single fabric response function in addition to the isotropic ice viscosity. The predicted responses in uniaxial compression and simple shear are determined. While the uniaxial response yields an explicit relation between the axial strain rate and stress, it is found that the shear response is governed by three, complicated, coupled relations between the shear strain rate and three deviatoricstress components. The new result derived here is the solution of this system: an explicit relation between the shear strain rate and shear stress. Correlation of these relations with idealized uniaxial and shear responses is then used to determine the required fabric function in the Model Law.
Ignacio Tirado - One of the best experts on this subject based on the ideXlab platform.
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Financing Micro-Businesses and Uncitral's Model Law on Secured Transactions
Social Science Research Network, 2017Co-Authors: Louise Gullifer, Ignacio TiradoAbstract:An overwhelming proportion of businesses in the world are very small, consisting of just one person with no or very few employees. Despite the small size of such businesses, it is extremely important to the economic wellbeing of states that they thrive and grow. In order to achieve this, access to finance is critical. While there have been some positive developments towards this goal, such as Government-run programmes to foster the creation of start-ups (mostly micro-businesses) and to enhance access to finance for smaller enterprises, or the widespread growth of microfinance in developing and middle income countries, these measures tend to be limited in their operation and usefulness. Secured financing, especially when provided by financial institutions, is necessary for most micro-businesses to achieve their potential, but access to this type of financing is, at present, restricted and, in some situations, non-existent. The legal structure for secured financing provided by the UNCITRAL Model Law can alleviate some of the problems preventing access to secured financing for micro-businesses. This paper examines these problems, and the difference that adoption of the Model Law system could make. It also identifies some areas in which the Model Law is not entirely suitable for the financing of micro-businesses, as well as specific issues which must be addressed by other areas of Law and regulation if financing to micro-businesses is to flourish. While the primary focus is on micro-businesses in developing economies, it is suggested that the problems faced by micro-businesses in accessing finance arise even in the more developed jurisdictions, and that at least some of the solutions suggested are appropriate for consideration in all parts of the world.
Rhys Bollen - One of the best experts on this subject based on the ideXlab platform.
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harmonisation of international payment services Law part 1 the uncitral Model Law
2008Co-Authors: Rhys BollenAbstract:The UNCITRAL Model Law on international credit transfers was adopted 16 years ago this year, and so it seems an appropriate time to look back on its effectiveness and implementation. The article introduces concept of harmonisation and how it has been applied in international payment system Law. It examines some key issues with the Model Law and discusses its implementation to date in the European Union.
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harmonisation of international payment services Law part 2 us article 4a
2008Co-Authors: Rhys BollenAbstract:This article reviews Article 4A of the Uniform Commercial Code, which is United States’ Model domestic Law on funds transfers. After a general introduction to the Code, this article reviews of how Article 4A deals with a number of key international payment issues. It concludes by comparing the US regime to the UNCITRAL Model Law on credit transfers discussed in the previous article.
