The satellite network does not have the IP layer where the IPsec [2][3] is designed for. Therefore, a new algorithm is needed to secure the satellite link at link layer or physical layer. This paper will give a short analysis on the advantages and disadvantages of the MPEG-2 TS encryption and present an approach trying to use the extension header of Unidirectional Lightweight Encapsulation (ULE...

In this study, a time-dependent 2D axisymmetric model of a multilayer hollow fiber composite membrane for gas separation is proposed. In spite of the common multilayer membranes, which a dense layer coated on a porous support layer and subjected into the feed stream, here, the porous support is exposed to the feed gas. In this regard, the governing equations of species transport are developed f...

We compared the results of 12 recently calibrated regional SPARROW (SPAtially Referenced Regressions On Watershed attributes) models covering most of the continental United States to evaluate the consistency and regional differences in factors affecting stream nutrient loads. The models - 6 for total nitrogen and 6 for total phosphorus - all provide similar levels of prediction accuracy, but th...

The Afon Goch (Anglesey, UK) is a short (12 km source to estuary) stream highly contaminated by acid mine drainage (AMD) throughout its length, due to past-mining at the head of the stream. Metal distribution is strongly controlled by the pH, which increases downstream particularly at confluences with two unpolluted tributaries. A pH increase causes precipitation of metals, primarily Fe as hydr...

The McMurdo dry valleys of Antarctica represent the largest of the ice-free areas on the Antarctic continent, containing glaciers, meltwater streams, and closed basin lakes. Previous geochemical studies of dry valley streams and lakes have addressed chemical weathering reactions of hyporheic substrate and geochemical evolution of dry valley surface waters. We examine cation transport and exchan...

The high density of animal production in southeastern Coastal Plain watersheds has caused some soils to contain excess amounts of plant–available soil phosphorus (P). Runoff, erosion, and leaching can transport P to surface water systems and out of these watersheds. High P concentrations in downstream aquatic ecosystems can increase the risk of eutrophication. Our objectives were to determine s...

a r t i c l e i n f o The Yangtze River dominates the drainage of eastern Asia, yet the processes that control erosion within the basin are obscure, making the interpretation of the detritus record difficult. In this study we used U–Pb dating of zircon grains from the modern main stream and major tributaries to identify the sources of sediment production, based on the diversity of zircon ages a...

Catchment-scale chemical transport is jointly controlled by hydrological and chemical processes. Water may take a complex set of flowpaths underground toward the stream, carrying soluble substances with it. Some chemical constituents are nonreactive; these act as passive tracers, moving with the water. Other constituents react with the porous medium; concentrations of these reactive tracers rev...

This study examines the interactions among geomorphic and biogeographic processes that govern the invasion by two contrasting exotic plant species—a shrub, scotch broom (Cytisus scoparius) and an herb, foxglove (Digitalis purpurea), over several decades of road and stream networks in the H.J. Andrews Experimental Forest in western Oregon. Distributions of C. scoparius and D. purpurea were mappe...