Experience in highly parallel processing using DAP

Distributed Array Processors (DAP) have been in day to day use for ten years and a large amount of user experience has been gained. The profile of user applications is similar to that of the Massively Parallel Processor (MPP) working group. Experience has shown that contrary to expectations, highly parallel systems provide excellent performance on so-called dirty problems such as the physics part of meteorological codes. The reasons for this observation are discussed. The arguments against replacing bit processors with floating point processors are also discussed

The scheduling of sparse matrix-vector multiplication on a massively parallel dap computer

An efficient data structure is presented which supports general unstructured sparse matrix-vector multiplications on a Distributed Array of Processors (DAP). This approach seeks to reduce the inter-processor data movements and organises the operations in batches of massively parallel steps by a heuristic scheduling procedure performed on the host computer. The resulting data structure is of particular relevance to iterative schemes for solving linear systems. Performance results for matrices taken from well known Linear Programming (LP) test problems are presented and analysed

Development of material specifications and qualifications of polymeric materials for the jpl spacecraft materials guidebook. 1- epoxide adhesives special report no. 1

Outgassing characteristics of nine epoxide adhesives, and thermal vacuum performance for adhesives teste

Development of material specifications and qualifications of polymeric materials for the jpl spacecraft materials guidebook. ii- rtv silicone adhesives and potting compounds special report no. 2

Silicone rubber adhesives and potting compounds - polymeric materials for spacecraf

Preventive Detention in California: Can Some Criminal Defendants Be Detained Prior to Trial?

In recent years there has been a growing concern with the need to reform the procedures for releasing criminal defendants prior to trial. Many states have changed their laws to emphasize release of the defendant on his own recognizance rather than release when the defendant posts bail. However, there is also a growing concern over the release of dangerous defendants, i.e. those defendants who might commit another crime if released prior to trial. Assembly Bill 2834 was introduced in the 1971 Session of the California Legislature, but the bill failed to pass. A.B. 2834 would have made substantial changes in California law. The bill would have changed the law on pre-trial release of criminal defendants to emphasize release on O.R. (own recognizance). In addition A.B. 2834 would have allowed the arraigning magistrate to detain certain classes of defendants prior to trial. This comment briefly discusses the changes in pre-trial release as proposed by the bill and then analyzes the preventive detention provisions of the bill. The author attempts to determine which defendants, if any, can rationally be detained as a means of preventing crime committed during pre-trial release

Development of material specifications and qualifications of polymeric materials for the jpl spacecraft materials guide book. iii- polyfluorocarbon films special report no. 3

Outgassing studies of polyfluorocarbon films - investigation of polymers as spacecraft construction material

Absolute absorption cross sections of ozone at 300 K, 228 K and 195 K in the wavelength region 185-240 nm

An account is given of progress of work on absorption cross section measurements of ozone at 300 K, 228 K and 195 K in the wavelength region 185-240 nm. In this wavelength region, the penetration of solar radiation into the Earth's atmosphere is controlled by O2 and O3. The transmitted radiation is available to dissociate trace species such as halocarbons and nitrous oxide. We have recently measured absolute absorption cross sections of O3 in the wavelength region 240-350 nm (Freeman et al., 1985; Yoshino et al., 1988). We apply these proven techniques to the determination of the absorption cross section of O3 at 300 K, 228 K and 195 K throughout the wavelength region 185-240 nm. A paper titled 'Absolute Absorption Cross Section Measurements of Ozone in the Wavelength Region 185-254 nm and the Temperature Dependence' has been submitted for publication in the Journal of Geophysical Research

Determination of spectroscopic properties of atmospheric molecules from high resolution vacuum ultraviolet cross section and wavelength measurements

Progress is given on work on: cross section measurements in the transmission window regions of the Schumann-Runge bands of oxygen; the determinations of predissociation linewidths; the theoretical calculation of band oscillator strengths of the Schumann-Runge absorption bands of O-16O-18; the determination of molecular spectroscopic constants; and the combined Herzberg continuum cross sections. The experimental investigations relevant to the cross section measurements, predissociation linewidths, and molecular spectroscopic constants are effected at high resolution with a 6.65 m scanning spectrometer which is, by virtue of its small instrumental width (FWHM = 0.0013 nm), suitable for cross section measurements of molecular bands with discrete rotational structure. Such measurements are needed for accurate calculations of the stratospheric production of atomic oxygen and heavy ozone formed following the photo-predissociation of O-16O-18 by solar radiation penetrating between the absorption lines of O-16(sub 2)

Coupled Cluster Treatment of the XY model

We study quantum spin systems in the 1D, 2D square and 3D cubic lattices with nearest-neighbour XY exchange. We use the coupled-cluster method (CCM) to calculate the ground-state energy, the T=0 sublattice magnetisation and the excited state energies, all as functions of the anisotropy parameter $\gamma$. We consider $S=1/2$ in detail and give some results for higher $S$. In 1D these results are compared with the exact $S=1/2$ results and in 2D with Monte-Carlo and series expansions. We obtain critical points close to the expected value $\gamma=0$ and our extrapolated LSUBn results for the ground-state energy are well converged for all $\gamma$ except very close to the critical point.Comment: 11 pages, Latex, 4 postscript figure, accepted by J.Phys.: Condens. Matte

Building solidarity through comparative lived experiences of post-conflict: Reflections on two days of dialogue

Occasions for in-depth dialogue among academics in times of conflict are rare. Drawing upon such a dialogue between Syrian academics and international counterparts from contexts undergoing conflict or grappling with post-conflict legacies, we identity seven dominant themes that emerged from these discussions and reflect on participants’ strategic insights and mutual support, in addition to highlighting the consciousness that was raised around the agency, limitations, complicity and intergenerational legacies borne by academics and the academy in crisis contexts