9,312 research outputs found

    Storing hydrogen in the form of light alloy hydrides

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    Different hydrides are investigated to find a system with a sufficiently high storage density (at least 3%). The formation of hydrides with light alloys is examined. Reaction kinetics for hydride formation were defined and applied to the systems Mg-Al-H, Mg-Al-Cu-H, Ti-Al-H, Ti-Al-Cu-H, and Ti-Al-Ni-H. Results indicate that the addition of Al destabilizes MgH2 and TiH2 hydrides while having only a limited effect on the storage density

    The Evolution of Securitization in Multifamily Mortgage markets and Its Effect on lending Rates

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    Loan purchase and securitization by Freddie Mac, Fannie Mae and private-label commercial mortgage-backed securities (CMBS) grew rapidly during the 1990s and accounted for more than one-half of the net growth in multifamily debt over the decade. By facilitating the integration of the multifamily mortgage market into the broader capital markets, securitization helped to create new sources of credit as some traditional portfolio investors—savings institutions and life insurers—reduced their share of loan holdings. A model of commercial mortgage rates at life insurers, expressed relative to a comparable-term Treasury yield, was estimated over a twenty-two-year period. The parameter estimates supported an option-based pricing model of rate determination; proxies for CMBS activity showed no significant effect.

    Non-universality in Micro-branching Instabilities in Rapid Fracture: the Role of Material Properties

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    In spite of the apparent similarity of micro-branching instabilities in different brittle materials, we propose that the physics determining the typical length- and time-scales characterizing the post-instability patterns differ greatly from material to material. We offer a scaling theory connecting the pattern characteristics to material properties (like molecular weight) in brittle plastics like PMMA, and stress the fundamental differences with patterns in glass which are crucially influenced by 3-dimensional dynamics. In both cases the present ab-initio theoretical models are still too far from reality, disregarding some fundamental physics of the phenomena.Comment: 4 pages, 6 figures, PRL submitte

    Dislocation plasticity in thin metal films

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    This article describes the current level of understanding of dislocation plasticity in thin films and small structures in which the film or structure dimension plays an important role. Experimental observations of the deformation behavior of thin films, including mechanical testing as well as electron microscopy studies, will be discussed in light of theoretical models and dislocation simulations. In particular, the potential of applying strain-gradient plasticity theory to thin-film deformation is discussed. Although the results of all studies presented follow a “smaller is stronger” trend, a clear functional dependence has not yet been established

    Drip and Mate Operations Acting in Test Tube Systems and Tissue-like P systems

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    The operations drip and mate considered in (mem)brane computing resemble the operations cut and recombination well known from DNA computing. We here consider sets of vesicles with multisets of objects on their outside membrane interacting by drip and mate in two different setups: in test tube systems, the vesicles may pass from one tube to another one provided they fulfill specific constraints; in tissue-like P systems, the vesicles are immediately passed to specified cells after having undergone a drip or mate operation. In both variants, computational completeness can be obtained, yet with different constraints for the drip and mate operations

    Lender Liability: A Survey of Common-Law Theories

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    Lender liability litigation has increased dramatically over the past several years. The increase in claims is hardly surprising when one considers recent multimillion dollar recoveries.\u27 Such well-publicized verdicts against lenders serve to encourage borrowers to defend even routine collection claims by striking out at the lender. Most often borrowers bring lender liability suits following commercial loan defaults. These suits are based on a number of common-law theories for liability including: breach of contract, breach of fiduciary duty,\u27 and breach of good faith, as well as fraud, duress, interference, and negligence. Some suits also raise statutory claims under the bankruptcy laws, the federal securities laws, the tax laws, the environmental laws,\u27 and the Racketeer Influenced and Corrupt Organizations Act (RICO).\u27 The success of many of these theories of liability has broadened the scope of lender liability and has helped borrowers fight back against overreaching lenders. Because many of the theories are relatively new to the banking area, however, courts have yet to define the theories\u27 parameters. This lack of judicial guidance leaves lenders in a difficult position. They face harsh economic consequences for failure to aid a troubled debtor, and potential liability if they do become involved. The uncertainty of the law makes it difficult for lenders to evaluate their risks. Consequently, evaluation has become more expensive. This evaluation expense and other increased costs eventually are passed onto borrowers and other bank customers. Furthermore, lenders often re-act by narrowing or curtailing important lending functions. Parts II and III of this Note describe the most prevalent theories of lender liability, focusing on common-law theories and highlighting prominent cases under each theory. Conflicts among jurisdictions are emphasized to show the need for guidelines and standardization. Part IV analyzes the impact of increased liability on lenders, and Part V examines the judiciary\u27s response depicted by several recent cases. Finally, Part VI concludes that until a body of law evolves in the area of lender liability, both lenders and borrowers will bear the costs of expanded and uncertain claims against lenders

    Unsteady Crack Motion and Branching in a Phase-Field Model of Brittle Fracture

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    Crack propagation is studied numerically using a continuum phase-field approach to mode III brittle fracture. The results shed light on the physics that controls the speed of accelerating cracks and the characteristic branching instability at a fraction of the wave speed.Comment: 11 pages, 4 figure
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