11,743 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

    Solutions without singularities in gauge theory of gravitation

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    A de-Sitter gauge theory of the gravitational field is developed using a spherical symmetric Minkowski space-time as base manifold. The gravitational field is described by gauge potentials and the mathematical structure of the underlying space-time is not affected by physical events. The field equations are written and their solutions without singularities are obtained by imposing some constraints on the invariants of the model. An example of such a solution is given and its dependence on the cosmological constant is studied. A comparison with results obtained in General Relativity theory is also presented. Keywords: gauge theory, gravitation, singularity, computer algebraComment: 9 pages, no figure

    Elementary Particles and Spin Representations

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    We emphasize that the group-theoretical considerations leading to SO(10) unification of electro-weak and strong matter field components naturally extend to space-time components, providing a truly unified description of all generation degrees of freedoms in terms of a single chiral spin representation of one of the groups SO(13,1), SO(9,5), SO(7,7) or SO(3,11). The realization of these groups as higher dimensional space-time symmetries produces unification of all fundamental fermions is a single space-time spinor.Comment: 4 page

    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

    Finite Element Analysis of Strain Effects on Electronic and Transport Properties in Quantum Dots and Wires

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    Lattice mismatch in layered semiconductor structures with submicron length scales leads to extremely high nonuniform strains. This paper presents a finite element technique for incorporating the effects of the nonuniform strain into an analysis of the electronic properties of SiGe quantum structures. Strain fields are calculated using a standard structural mechanics finite element package and the effects are included as a nonuniform potential directly in the time independent Schrodinger equation; a k-p Hamiltonian is used to model the effects of multiple valence subband coupling. A variational statement of the equation is formulated and solved using the finite element method. This technique is applied to resonant tunneling diode quantum dots and wires; the resulting densities of states confined to the quantum well layers of the devices are compared to experimental current-voltage I(V) curves.Comment: 17 pages (LaTex), 18 figures (JPEG), submitted to Journal of Applied Physic

    Managing human resources for productivity growth.

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    Mergers and Acquisitions: The Quintessence of Change

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    I wrote a book in the mid-\u2770\u27s entitled ANATOMY OF A MERGER, a guide to handling negotiated acquisitions. Looking back from the vantage point of a decade later, I was struck by the tremendous changes that had taken place in terms of how acquisitions of public companies are accomplished. Today, the hostile takeover has so permeated the public company acquisition scene that it has entirely altered the way that lawyers and others who ply this trade accomplish their goals

    . . . Skepticism But Not Cynicism : Chancellor Allen\u27s Scrutiny of Special Committees

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    This Essay is part of a tribute issue that was compiled in honor of William T. Allen, Chancellor of the Delaware Court of Chancery, after he announced his intention not to seek reappointment

    . . . Skepticism But Not Cynicism : Chancellor Allen\u27s Scrutiny of Special Committees

    Get PDF
    This Essay is part of a tribute issue that was compiled in honor of William T. Allen, Chancellor of the Delaware Court of Chancery, after he announced his intention not to seek reappointment
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