Measurement of Dihedral Angle Errors of a Large-Aperture Space Retroreflector: Separation of the Effect of Sag Due to Gravity

A 50-cm diameter hollow cube-corner retroreflector for a space application was tested with a 60-cm interferometer. To separate the effect of sag due to gravity, the interferograms were taken at six rotational positions, with the retroreflector mounted horizontally. The zero-gravity dihedral angles and the effect of sag were estimated from the interferograms.     

A Solution to the Weber Location Problem on the Sphere

In this paper we present an algorithm for the solution of the minisum location problem on the sphere. The algorithm is finite for the solution within a given accuracy of the optimal solution.     

Excitation and emission of metal electrons in atom-surface collisions

Electron-hole pair excitation and ionization probabilities are calculated for atomic collisions with metal surfaces at high incident energies. The method adopted is based on a Sudden Collision Approximation, and a realistic model is employed for the bound and continuum electronic states involved. The parameters used in the calculations are for Ar, He, H atoms impinging on a Li surface at 300 eV. The main results are: (1) Only single electron-hole pair excitations are important; multiple pair contributions are small. (2) The transitions are dominated by the behavior of the electronic wavefunctions in the tunneling region and may serve as a probe of this regime. (3) The excitation efficiency is in the order H ? Ar ? He, the effectiveness of hydrogen being due to its stronger, longer-range coupling. (4) The maximum excitation probabilities are for electrons ejected with relatively low excess energies. (5) Total transition probabilities are about 0.5 per collision for H, and about 0.1 for Ar, indicating that these are important, easily detectable processes. Experiments in this field should provide important information on electronic wavefunctions at the metal-gas interface, and on gas-metal interactions at high energies.     

A Finite Horizon Production Model with Variable Production Rates and Constant Demand Rate

In this paper we present a finite horizon single product single machine production problem. Demand rate and all the cost patterns do not change over time. However, end of horizon effects may require production rate adjustments at the beginning of each cycle. It is found that no such adjustments are required. The machine should be operated either at minimum speed (i.e. production rate = demand rate; shortage is not allowed), avoiding the buildup of any inventory, or at maximum speed, building up maximum inventories that are controlled by the optimal production lot size.     

Location on a One-Way Rectilinear Grid

This paper considers two basic location problems — the Weber problem and the minimax problem-on a regular grid of alternating one-way routes or streets. Both the facility to be located and the demand points are restricted to any point on the network. The one-way restriction is often used for efficiency in traffic flow, but complicates the distances in the system.     

Lower bounds based on linear programming for the quadratic assignment problem

In this paper we prove that the Classical Gilmore-Lawler lower bound for the quadratic assignment problem is equivalent to a solution of a certain linear programming problem. By adding additional constraints to this linear programming problem we derive a lower bound which is at least as good as the Gilmore-Lawler lower bound.Some of this research was done while the author was on sabbatical leave at the Department of Management, The Hong Kong University of Science and Technology, Kowloon, Hong Kong.     

An ion mobility spectrometry/mass spectrometry (IMS/MS) study of the site of protonation in anilines

Ion mobility spectrometry (IMS) and IMS/MS techniques were used to differentiate between nitrogenprotonated and carbon-protonated anilines, both of which coexist under the conditions of the IMS. Analysis of the results led to the conclusion that the former species had lower mobilities than the latter. This was attributed mainly to charge delocalization in the ring-protonated species, which results in a weaker interaction with the drift gas molecules. Furthermore,meta-alkyl substitution enhanced ring protonation, while in 2-chloroaniline the nitrogenprotonated species was predominant, as expected.