Millimeter and submillimeter wave measurements of complex optical and dielectric parameters of materials

These coolant materials were chosen for the first in this series of measrements of the complex parameters of liquids over the entire millimeter and submillimeter wavelength range of the spectrum. The fluorocarbon coolants not reported here exhibit an order of magnitude lower loss. It is the characteristic of these liquids that the absorption coefficient increases monotonically with frequency.Partially supported by the Office of Fusion Energy, U.S. Department of Energy, under Contract W-7405-eng-26 with Union Carbide Corporation.Supported by the National Science Foundation.     

Commutativity for a Certain Class of Rings

We first establish the commutativity for the semiprime ring satisfying [x ⁿ , y]x ^r = ±y ^s[x, y ^m]y ^t for all x, y in R, where m, n, r, s, and t are fixed non-negative integers, and further, we investigate the commutativity of rings with unity under some additional hypotheses. Moreover, it is also shown that the above result is true for s-unital rings. Also, we provide some counterexamples which show that the hypotheses of our theorems are not altogether superfluous. The results of this paper generalize some of the well-known commutativity theorems for rings which are right s-unital.     

Effects of multiple blade interaction on the containment of blade fragments during a rotor failure

A finite element analysis is used to study the impact and the containment aspects of rotor blade fragments that are produced during a aircraft jet engine rotor failure. The impact and containment studies are performed on a ring-type containment structure and various fragment types are considered in this study. For each type of fragment, the ring thickness is varied incrementally and the ring response, residual kinetic energy level of the fragments, magnitude of impact forces and the overall containment or failure are determined. First, only a single fragment is considered and the rotor is assumed to contain no other blades. Next, the remaining blades are introduced and the effects of multiple collisions with the other blades on the containment are analyzed. The explicit, nonlinear finite element code Dyna3d is used for the numerical computations in this study and the results are compared with the experimental results performed on a T58 rotor at the spin facility of the Naval Air Propulsion Test Center.     

Temperature program optimization by computer simulation for the capillary GC analysis of fatty acid methyl esters on biscyanopropyl siloxane phases

The selectivity of capillary columns coated with biscyanopropyl siloxane stationary phases for the separation of fatty acid methyl esters has been optimized by means of computer-assisted column temperature optimization software. Temperature programming rates yielding the highest resolution in the shortest analysis time were selected for split, splitless, and on-column injection operated in the constant pressure and pressure programmed modes.     

Conformational Aspects of Many-Membered Rings

The stereochemistry of the various chemical grouping which constitute the structural units of ring systems is first reviewed. It is then shown that the strain-free possibilities even of large rings are restricted, and that the ring conformation theoretically derived generally correspond to those found by physical methods. Variations of physical properties and of cyclization yield in homologous series are explained on a conformational basis.     

Sofic groups and direct finiteness

We construct an analogue of von Neumann's affiliated algebras for sofic group algebras over arbitrary fields. Consequently, we settle Kaplansky's direct finiteness conjecture for sofic groups.     

Implementing the ALGOL 68 heap

The implications of the heap, reference variables and global generators in ALGOL 68 are examined and some notes on possible implementation mechanisms are presented. In particular the use or simulation of hardware with segment addressing facilities is discussed.     

Some constructions of systematic authentication codes using galois rings

For q = p ^m and m ≥ 1, we construct systematic authentication codes over finite field using Galois rings. We give corrections of the construction of [2]. We generalize corresponding systematic authentication codes of [6] in various ways.     

Cyclic Codes Over\mathbb{Z}_{4} of Even Length

We determine the structure of cyclic codes over for arbitrary even length giving the generator polynomial for these codes. We determine the number of cyclic codes for a given length. We describe the duals of the cyclic codes, describe the form of cyclic codes that are self-dual and give the number of these codes. We end by examining specific cases of cyclic codes, giving all cyclic self-dual codes of length less than or equal to 14. San Ling - The research of the second named author is partially supported by research Grants MOE-ARF R-146-000-029-112 and DSTA R-394-000-011-422.