The problem of estimating the variance of the ratio estimator in sampling with probability proportional to aggregate size is investigated. The form of nonnegative ...

This chapter addresses the common practices and test methods (standards) that are used for certification programs for the basic material categories of soils and aggregate, asphalt mixture, and ...

Researchers have found evidence that "marine snow" -- aggregates of organic material floating in water bodies -- may act as microscopic, island-like refuges for pathogens, or disease-causing organisms ...