[en] The ERATO code computes the stability of an equilibrium with respect to the linear MHD equation. The ERATO code is divided into 5 programs (ERATO1 through ERATO5). This report documents some minor changes made in ERATO3 and a major reorganization of ERATO4. The changes were made to reduce drastically the amount of secondary storage needed by the codes and at the same time improve the efficiency of ERATO4. The ultimate goal is to allow the successful completion of runs with finer meshes than are currently possible. ERATO4 takes given matrices, A and B, and a shift parameter, ω₀, and computes the Choleski factorization (U/sup T/DU) of the matrix A - ω₀B. It then uses the factorization to implement inverse iteration to find the eigenvalue of the generalized eigenvalue problem A - lambda B closest to ω₀ and its corresponding eigenvector. The matrices A and B are highly structured and quite sparse. Both are symmetric and B is positive definite. Each block consists of 16 square subblocks. 9 figures

[en] Methods are presented for computing eigenpairs of the quadratic lambda-matrix, M lambda² + C lambda + K, where M, C, and K are large and sparse, and have special symmetry-type properties. These properties are sufficient to insure that all the eigenvalues are real and that theory analogous to the standard symmetric eigenproblem exists. The methods employ some standard techniques such as partial tri-diagonalization via the Lanczos Method and subsequent eigenpair calculation, shift-and- invert strategy and subspace iteration. The methods also employ some new techniques such as Rayleigh-Ritz quadratic roots and the inertia of symmetric, definite, quadratic lambda-matrices

No abstract available

[en] Autonomous underwater vehicles have traditionally been powered by low energy density lead-acid batteries. Recently, advanced battery technologies and H₂-O₂ fuel cells have become available, offering significant improvements in performance. This paper compares the solid polymer fuel cell to the lithium-thionyl chloride primary battery, sodium-sulfur battery, and lead acid battery for a variety of missions. The power system performance is simulated using computer modelling techniques. Performance envelopes are constructed, indicating domains of preference for competing power system technologies. For most mission scenarios, the solid polymer fuel cell using liquid reactant storage is the preferred system. Nevertheless, the advanced battery systems are competitive with the fuel cell systems using gaseous hydrogen storage, and they illustrate preferred performance for missions requiring high power density. 11 figs., 4 tabs., 15 refs

[en] In this paper an iterative technique is discussed for finding the algebraic alloy smallest (or largest) eigenvalue of the generalized eigenvalue problem. A-lambda M, where A and M are real, symmetric, and M is positive definite. It is assumed that A and M are such that it is undesirable to factor the matrix A-sigma M for any value of sigma. It is proved that the algorithm is globally convergent, and that convergence is asymptotically quadratic. Finally, the modifications required in the algorithm to make it computationally feasible are discussed

[en] Utility vehicles provide ground transportation for crew and electric power at work sites that lack grid supply. The performances of utility vehicles designed with conventional architectures (spark ignition engine for propulsion and a motor generator for electric power) and with a fuel cell/battery architectures, are compared over a range of vehicle missions. Results indicate that fuel cell/battery hybrid systems are lighter than conventional systems for missions requiring short driving distances and work site power levels exceeding 10 kW. Conventional spark ignition engine/gen-set power systems are lighter for missions requiring more than 1 hour of driving and less than 10 kW of work site power. Fuel cell/battery systems are more efficient than spark ignition engine/gen-set systems for all missions. 7 figs., 3 tabs., 20 refs

[en] Critical telephone network systems are currently protected from electric utility power failures by a backup system consisting of lead-acid batteries and an engine-alternator. It is considered here an alternate power system where less expensive off-peak commercial electricity electrolyses water, while fuel cells draw continuously on the stored gas products to provide direct current for the protected equipment. The lead acid batteries are eliminated. The benefits and costs of the existing and alternate systems in scenarios with various system efficiencies, capital costs, and electric utility rates and incentives, are compared. In today's conditions, the alternate system is not economical; however, cost and performance feasibility domains are identified. 2 figs., 4 tabs., 12 refs

[en] Algorithms are presented for computing some of the eigenvalues and their associated eigenvectors of the quadratic lambda-matrix M lambda² C lambda + K. M, C, and K are assumed to have special symmetry-type properties which insure that theory analogous to the standard symmetric eigenproblem exists. The algorithms are based on a generalization of the Rayleigh quotient and the Lanczos method for computing eigenpairs of standard symmetric eigenproblems. Monotone quadratic convergence of the basic method is proved. Test examples are presented

[en] A study of the relationship between local thermodynamic properties, magnetic field strengths, and Hall currents in the arc region of magnetoplasmadynamic (MPD) accelerators is presented

[en] This report is the twenty-fourth in the series of progress reports of the Mathematics and Statistics Research Department of the Computer Sciences Division, Union Carbide Corporation - Nuclear Division (UCC-ND). Part A records research progress in biometrics research, materials science applications, model evaluation, moving boundary problems, multivariate analysis, numerical linear algebra, risk analysis, and complementary areas. Collaboration and consulting with others throughout the UCC-ND complex are recorded in Part B. Included are sections on biology and health sciences, chemistry, energy, engineering, environmental sciences, health and safety research, materials sciences, safeguards, surveys, and uranium resource evaluation. Part C summarizes the various educational activities in which the staff was engaged. Part D lists the presentations of research results, and Part E records the staff's other professional activities during the report period