Recent changes of water discharge and sediment load in the Yellow River basin, China

The Yellow River basin contributes approximately 6% of the sediment load from all river systems globally, and the annual runoff directly supports 12% of the Chinese population. As a result, describing and understanding recent variations of water discharge and sediment load under global change scenarios are of considerable importance. The present study considers the annual hydrologic series of the water discharge and sediment load of the Yellow River basin obtained from 15 gauging stations (10 mainstream, 5 tributaries). The Mann-Kendall test method was adopted to detect both gradual and abrupt change of hydrological series since the 1950s. With the exception of the area draining to the Upper Tangnaihai station, results indicate that both water discharge and sediment load have decreased significantly (p<0.05). The declining trend is greater with distance downstream, and drainage area has a significant positive effect on the rate of decline. It is suggested that the abrupt change of the water discharge from the late 1980s to the early 1990s arose from human extraction, and that the abrupt change in sediment load was linked to disturbance from reservoir construction.Geography, PhysicalGeosciences, MultidisciplinarySCI(E)43ARTICLE4541-5613

Using Projection Analysis in Compiling Lazy Functional Programs

Projection analysis is a technique for finding out information about lazy functional programs. We show how the information obtained from this analysis can be used to speed up sequential implementations, and introduce parallelism into parallel implementations. The underlying evaluation model is evaluation transformers, where the amount of evaluation that is allowed of an argument in a function application depends on the amount of evaluation allowed of the application. We prove that the transformed programs preserve the semantics of the original programs. Compilation rules, which encode the information from the analysis, are given for sequential and parallel machines. 1 Introduction A number of analyses have been developed which find out information about programs. The methods that have been developed fall broadly into two classes, forwards analyses such as those based on the ideas of abstract interpretation (e.g. [9, 18, 19, 7, 17, 12, 4, 20]), and backward analyses such as those based..

PERs Generalise Projections for Strictness Analysis (Extended Abstract)

We show how Wadler and Hughes's use of Scott projections to describe properties of functions ("Projections for Strictness Analysis", FPCA 1987) can be generalised by the use of partial equivalence relations. We describe an analysis (in the form of an abstract interpretation) for identifying such properties for functions defined in the simply typed -calculus. Our analysis has a very simple proof of correctness, based on the use of logical relations. We go on to consider how to derive `best' correct interpretations for constants

Strictness Meets Data Flow

Abstract. Properties of programs can be formulated using various techniques: dataflow analysis, abstract interpretation and type-like inference systems. This paper reconstructs strictness analysis (establishing when function parameters are evaluated in a lazy language) as a dataflow analysis, initially at first order, then at higher order by expressing the dataflow properties as an effect system. Strictness properties so expressed give a clearer operational understanding and enable a range of additional optimisations including implicational strictness. At first order strictness effects have the expected principality properties (best-property inference) and can be computed simply; without polymorphic effects principality is lost at higher order. However, adding both polymorphic effects and polymorphic type instantiation to restore principality exposes novel issues.