11,743 research outputs found
Storing hydrogen in the form of light alloy hydrides
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
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
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
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
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
Mergers and Acquisitions: The Quintessence of Change
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
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
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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