雪山工程-水力发电与跨流域调水综合工程

雪山工程位于澳大利亚东南部的墨累达令流域,是一项在墨累河和马兰比吉河上进行水力发电、农业灌溉调水和河道管理的综合工程。从工程管理、规划、主要设施建设、调水量、水权、用水分配原则以及一些环境问题的角度介绍雪山工程的情况。     

Imaging colloidal gold labels in LVSEM

On biological samples, the topographic imaging capabilities of the new generation of scanning electron microscopes (SEM) (those having both field-emission guns and low aberration lenses) rival those of the replica techniques. In addition, they permit the localization of specific molecules on the sample surface using one of several labeling techniques utilizing heavy metal colloids. Normally, colloidal gold can be detected in the SEM both by the secondary electron signal (shape) and by the backscattered electron signal (BSE, Z-contrast). The new instruments seem to produce their best topographic images using low-beam voltage (1–5 kV) where topographic contrast is higher and the required thickness of the metal coating is less (Haggis and Pawley 1988, Ris and Pawley 1988). Although the detection of backscattered electrons is more difficult at low-beam voltage, we are able to show here that the secondary electron (SE) signal produced with a 2–5-kV beam permits the unambiguous detection of gold particles as small as 5 nm on carbon-coated specimens while a 1-kV beam produces a high-quality topographic image of the same sample.     

Scientific modeling with massively parallel SIMD computers

A number of scientific models are discussed that possess a high degree of inherent parallelism. For simulation purposes this is exploited by employing a massively parallel SIMD (single instruction multiple data) computer. The authors describe one such computer, the distributed array processor (DAP), and discuss the optimal mapping of a typical problem onto the computer architecture to best exploit the model parallelism. By focusing on specific models currently under study, they exemplify the types of problems which benefit most from a parallel implementation. The extent of this benefit is considered relative to implementation on a machine of conventional architecture     

Monte-Carlo simulation of the order-disorder transition in the KDP-type structure

Monte Carlo simulations are presented for a model for the KDP-type structure, using a simplified pseudo-Ising model. Phase transitions occur for simulated temperatures that concur with analytical results in the limit of weak ordering fields. Significantly non-zero pseudo-spin correlations are found in the paraelectric phase only for the ordering on the PO₄ tetrahedra. Most of the computation is Boolean logic, making it ideal for the ICL Distributed Array Processor.