Dynamic programming and parallel computers

The computational theory of dynamic programming is examined from the viewpoint of parallel computation. A discussion of various forms of parallelism, the corresponding parallel algorithms, the applicability of the algorithms to different types of optimization problems, and their advantages over serial computation is presented. In addition, parallel aspects of various dimensionality reduction techniques such as state increment dynamic programming, successive approximations, and shift vectors are also given.This research was supported by the Air Force Office of Scientific Research, Contract No. F44620-70-C-0084.     

Fixed charge problems with identical fixed charges

The general problem considered by this paper is a special case of the fixed-charge problem. The further condition imposed is that all variables have the same associated fixed-charge. The problem is discussed in the context of a known commercial application, that being the cutting stock problem. The situation considered is that of cutting given numbers of small rectangles from large rectangular stock-plates. In many such situations major aims are to have low stock-plate usage and a low number of setups of the cutting equipment. These represent conflicting objectives capable of being combined by the use of fixed charges upon the setups but this paper presents an alternative approach incorporating direct manipulation of the number of setups involved in the solution. This approach is compared to a solution technique for the general fixed-charge problem.     

Towards the electrochemical manufacture of superconductor precursor films in the presence of an ultrasonic field

Films of TI-Pb-Sr-Ca-Cu superconductor precursor material have been synthesised. The films were electrodeposited onto polished Ag substrates, with and without the presence of an ultrasonic field in the solution, by applying a pulsed potential sufficiently large to cause reduction of the appropriate metallic cations. The deposition solution was composed of dehydrated metallic nitrate salts dissolved in dimethylsulfoxide. The morphology, and the compositions, of the films were analysed using scanning electron microscopy and emission dispersive spectroscopy respectively. Deposition in the presence of the ultrasonic field showed an increased deposition current, by a factor of 4, caused by mass transfer enhancements as a result of cavitation effects produced by the ultrasonic irradiation of the solution. These films were denser compared with those deposited without the presence of the ultrasound, displaying a void percentage of around 45%, and also displayed greater morphological homogeneity.     

Angular resolved photoemission from palladium single crystals

Photoelectron spectra emitted normal to Pd(001), (011) and (111) faces are presented for He I (21.2 eV) and for Ne I (16.8 eV) radiation. The spectra are different from each other, and in each case the Ne I spectra show a distinct narrowing compared to the He I spectra. Most of the features in all these spectra can be accounted for in terms of initial states only, if different cross-sections are assumed for bands derived from particular d orbitals. This analysis is consistent only for d orbitals related to surface rather than bulk co-ordinates. Spectral features which do not fit this analysis are found to be very sensitive to surface adsorption. An example of the variation in emission away from the surface normal is given.     

The production and properties of poly(vinylidene fluoride) rods oriented by drawing through a conical die

Highly oriented poly(vinylidene fluoride) rods have been produced by drawing isotropic polymer through a conical die. A range of oriented products was obtained, depending on the drawing temperature and the deformation ratio achieved. At low draw temperatures the draw ratio and final modulus are comparatively low, but a high Form I crystal content is obtained. At high draw temperatures the Form I content varies greatly with draw ratio, reaching high values at large draw ratios, where the highest-modulus samples were obtained.