Training sewing machine operators.

Includes advertising matter.

Co-operators' year book /

Description based on: 8th (1904); title from cover.

Decisions under uncertainty; drilling decisions by oil and gas operators.

Includes bibliography.

Physical impairment among industrial workers. A report based on the complete physical examination of one thousand white, male, machine and hand tool operators. A study made through the Industrial Health Conservancy Laboratories.

Mode of access: Internet.

Pittsburg Vein Operators' Association, complainant, vs. the Wheeling & Lake Erie Railroad Company, and B.A. Worthington, receiver of the Wheeling & Lake Erie Railroad Company, defendants. Memorandum respecting allocation of railroad expenses.

Before the Interstate Commerce Commission, no. 4116-1.

Testing milk and its products : a manual for dairy students, creamery and cheese factory operators, food chemists and dairy farmers /

Includes bibliographical notes and index.

Testing milk and its products; a manual for dairy students, creamery- and cheese factory operators, food chemists, and dairy farmers.

Mode of access: Internet.

The law of the sea : a manual of the principles of admiralty law for students, mariners, and ship operators /

Mode of access: Internet.

1963 census of commercial fisheries: number of operators and fishing vessels, employment and gross receipts, fishing regions, primary catch, and fishing gear, size of vessel, cost, and year purchased or built.

Cover title.

Questionnaire survey of VDT operators at the New York State Departments of Motor Vehicles and Taxation and Finance /

Cover title.

Aeronautic radio; a manual for operators, pilots, radio mechanics,

Mode of access: Internet.

Transparent boundary conditions for wave propagation on unbounded domains

The numerical solution of the time dependent wave equation in an unbounded domain generally leads to a truncation of this domain, which requires the introduction of an artificial boundary with associated boundary conditions. Such nonreflecting conditions ensure the equivalence between the solution of the original problem in the unbounded region and the solution inside the artificial boundary. We consider the acoustic wave equation and derive exact transparent boundary conditions that are local in time and can be directly used in explicit methods. These conditions annihilate wave harmonics up to a given order on a spherical artificial boundary, and we show how to combine the derived boundary condition with a finite difference method. The analysis is complemented by a numerical example in two spatial dimensions that illustrates the usefulness and accuracy of transparent boundary conditions.

Non-positivity of Groenewold operators

A central feature in the Hilbert space formulation of classical mechanics is the quantisation of classical Lionville densities, leading to what may be termed Groenewold operators. We investigate the spectra of the Groenewold operators that correspond to Gaussian and to certain uniform Lionville densities. We show that when the classical coordinate-momentum uncertainty product falls below Heisenberg's limit, the Groenewold operators in the Gaussian case develop negative eigenvalues and eigenvalues larger than 1. However, in the uniform case, negative eigenvalues are shown to persist for arbitrarily large values of the classical uncertainty product.