Submicron metal powders produced by ball milling with grinding aids

In ball milling metal powders to submicron size, various salts are more effective as grinding aids than conventional surfactants. Absolute ethyl alcohol is used as the grinding liquid

Tensor models and 3-ary algebras

Tensor models are the generalization of matrix models, and are studied as models of quantum gravity in general dimensions. In this paper, I discuss the algebraic structure in the fuzzy space interpretation of the tensor models which have a tensor with three indices as its only dynamical variable. The algebraic structure is studied mainly from the perspective of 3-ary algebras. It is shown that the tensor models have algebraic expressions, and that their symmetries are represented by 3-ary algebras. It is also shown that the 3-ary algebras of coordinates, which appear in the nonassociative fuzzy flat spacetimes corresponding to a certain class of configurations with Gaussian functions in the tensor models, form Lie triple systems, and the associated Lie algebras are shown to agree with those of the Snyder's noncommutative spacetimes. The Poincare transformations on the fuzzy flat spacetimes are shown to be generated by 3-ary algebras.Comment: 21 pages, no essential changes of contents, but explanations added for clarit

Prison Anger Reduction Programs Evaluation Development Project

This report describes efforts to develop Alaska-specific norms for the Minnesota Multiphasic Personality Inventory (MMPI), using the Megargee offender classification system, for use in program evaluations in Alaska correctional facilities, specifically for evaluation of three pilot anger reduction programs initiated at Alaska Department of Corrections institutions in late 1984/early 1985: (1) Women in Crisis (at Fairbanks Correctional Center); (2) M. E. N., Inc. (at Lemon Creek Correctional Center, Juneau); (3) Bering Sea Women's Group (at Nome Correctional Center). The report provides assessments of the three programs and the correctional centers where they were held and makes recommendations for completing the development of Alaska-specific MMPI-based norms and for the administration of the MMPI as pre- and post-test for measuring psychological changes — particularly in hostility/frustration levels — in participants in anger reduction programs.Alaska Council on Domestic Violence and Sexual AssaultIntroduction / Section I. History of the Project / Section II. Psychological Testing / Section III. Site Assessment — Facilities / Section IV. Site Assessment — Programs / Section V. Recommendations / APPENDICES / A. Domestic Violence Evaluation Project: Assessment of Programs for Anger Reduction in Incarcerated Alaskan Prisoners [Project proposal] / B. Letter from Nancy E. Schafer to Barbara Miklos, June 7, 1985 / C. Site Visits / D. Criminal Justice Assessment Cervices, Inc.: Experimental MMPI Scales Availabl

Non-BPS D-branes and M-theory

A dual pair of supersymmetric string theories that involves an asymmetric orbifold and an orientifold of Type II is considered. The D-branes of the orbifold theory (that were recently determined by Gutperle) are all non-BPS and do not carry any conserved gauge charges. It is shown that they carry non-trivial K-theory charges, and that they can be understood in terms of branes wrapping certain homology classes of the M-theory compactification. Using the adiabatic argument, dual partners of some of these non-BPS D-branes are proposed. The relations between these dual states are found to be in agreement with the M-theory description of the D-branes.Comment: 21 pages, 1 figure; harvmac b-mode; reference adde

Multi-instantons in seven dimensions

We consider the self-dual Yang-Mills equations in seven dimensions. Modifying the t'Hooft construction of instantons in $d=4$, we find $N$-instanton $7d$ solutions which depend on $8N$ effective parameters and are $E_{6}$-invariant.Comment: 9 pages, LaTeX, no figure

Alternatives for jet engine control

Alternatives to linear quadratic regulator theory in the linear case are examined along with nonlinear modelling and optimization approaches for global control. Context for the studies has been set by the DYNGEN digital simulator and by models generated for various phases of the F100 Multivariable Control Synthesis Program. With respect to the linear alternatives, the multivariable frequency domain is stressed. Progress is reported in both the direct algebraic approach to exact model matching, by means of stimulating work on the basic computational issues, and in the indirect generalized Nyquist approach. With respect to nonlinear modelling and optimization, the emphasis is twofold: the development of analytical nonlinear models of the jet engine and the use of these models in conjunction with techniques of mathematical programming in order to study global control over nonincremental portions of the flight envelope. The possibility of using tensor methods is explored

Fluid surface behavior in low gravity. Center discretionary fund no. 83-21

Measurements of rotating equilibrium bubble shapes in the low-gravity environment of a free-falling aircraft are presented. Emphasis is placed on bubbles which intersect the container boundaries. These data are compared with theoretical profiles derived from Laplace's formula and are in good agreement with the measurements. Two types of instability are explored. The first occurs when the baffle spacing is too large for the bubble to intersect both the top and bottom boundaries. The second occurs when the hydrostatic pressure beneath a displaced free surface does not compensate for pressure change due to capillary forces. The interface shape depends on the contact angle, the radius of intersection with container, and the parameter F which is a measure of the relative importance of centrifugal force to surface tension. For isolated bubbles, F has a maximum value of 1/2. A further increase in F causes the bubble to break contact with the axis of rotation. For large values of F, the bubble becomes more cylindrical and the capillary rise occurs over a thinner layer so that the small radius of curvature can generate enough pressure drop to balance the increased hydrostatic contribution

Strength and High-Temperature Stability of Dispersion Strengthened Nickel-MgO Alloys

Strength and high-temperature stability of dispersion strengthened nickel-magnesium oxide alloy

Box Graphs and Singular Fibers

We determine the higher codimension fibers of elliptically fibered Calabi-Yau fourfolds with section by studying the three-dimensional N=2 supersymmetric gauge theory with matter which describes the low energy effective theory of M-theory compactified on the associated Weierstrass model, a singular model of the fourfold. Each phase of the Coulomb branch of this theory corresponds to a particular resolution of the Weierstrass model, and we show that these have a concise description in terms of decorated box graphs based on the representation graph of the matter multiplets, or alternatively by a class of convex paths on said graph. Transitions between phases have a simple interpretation as `flopping' of the path, and in the geometry correspond to actual flop transitions. This description of the phases enables us to enumerate and determine the entire network between them, with various matter representations for all reductive Lie groups. Furthermore, we observe that each network of phases carries the structure of a (quasi-)minuscule representation of a specific Lie algebra. Interpreted from a geometric point of view, this analysis determines the generators of the cone of effective curves as well as the network of flop transitions between crepant resolutions of singular elliptic Calabi-Yau fourfolds. From the box graphs we determine all fiber types in codimensions two and three, and we find new, non-Kodaira, fiber types for E_6, E_7 and E_8.Comment: 107 pages, 44 figures, v2: added case of E7 monodromy-reduced fiber

Oblique and curved D-branes in IIB plane-wave string theory

Oblique Dp-branes in the maximally supersymmetric type IIB plane-wave background are constructed in terms of boundary states, as well as from the open string point of view. These Dp-branes, whose existence was anticipated by Hikida and Yamaguchi from general supersymmetry arguments, have an isometry that is a subgroup of the diagonal SO(4) symmetry of the background. The oblique D3-brane is found to preserve four dynamical and four kinematical supersymmetries while the oblique D5-brane preserves one half of both the dynamical and kinematical supersymmetries. We also discuss the open-string boundary conditions for curved D7- and D5-branes, and analyze their supersymmetry.Comment: 27 page