US-CHINA WORKSHOP ON ADVANCED COMPUTATIONAL MODELLING IN HYDROSCIENCE & ENGINEERING September 19-21, Oxford, Mississippi, USA MODELING HYDRODYNAMICS, CHANNEL MORPHOLOGY, AND WATER QUALITY USING CCHE1D
CCHE1D is a one-dimensional model for the simulation of unsteady flows, sediment transport, and water quality in stream networks. The model can be applied to a variety of engineering problems, but it is particularly useful in the determination of channel–watershed system responses to natural and man-made changes in both channels and upland areas. The model can be used in combination with the watershed model AGNPS in the analysis of watershed hydrology and nonpoint source pollution problems caused by erosion or pollutants such as nutrients and pesticides. CCHE1D’s flow module – CCHE1D-FL – computes one-dimensional unsteady flows in dendritic channel networks of arbitrary cross-sectional shapes. The sediment transport module – CCHE1D-ST – simulates the transport of sediment mixtures using a nonequilibrium approach, predicting sediment yields and channel morphological changes. The recently developed water quality module – CCHE1D-WQ – simulates transport and fate of pollutants in streams for continuous, unsteady flow conditions. The model computes advective-dispersive transport of a number of pollutants, simulating the biogeochemical processes of the main nutrient cycles, phytoplankton growth, and the process of eutrophication. GIS-based graphical software complements the modeling system, providing automated methods for watershed delineation, channel network generation, data transfers and conversions, and visualization.
One-dimensional numerical model for nonuniform sediment transport under unsteady flows in channel networks
In this study, the proposed one-dimensional model simulates the nonequilibrium transport of nonuniform total load under unsteady flow conditions in dendritic channel networks with hydraulic structures. The equations of sediment transport, bed changes, and bed-material sorting are solved in a coupling procedure with a direct solution technique, while still decoupled from the flow model. This coupled model for sediment calculation is more stable and less likely to produce negative values for bed-material gradation than the traditional fully decoupled model. The sediment transport capacity is calculated by one of four formulas, which have taken into consideration the hiding and exposure mechanism of nonuniform sediment transport. The fluvial erosion at bank toes and the mass failure of banks are simulated to complement the modeling of bed morphological changes in channels. The tests in several cases show that the present model is capable of predicting sediment transport, bed changes, and bed-material sorting in various situations, with reasonable accuracy and reliability.
Glycogen phosphorylase in lobster hepatopancreas: action of proteases on the enzyme
Abstract 1. 1. In lobster hepatopancreas, extracellular protreases cause the inactivation of glycogen phosphorylase. 2. 2. The proteolysis of glycogen phosphorylase purified from rabbit muscle by these proteases has been shown by SDS-polyacrylamide gel electrophoresis. 3. 3. A cell isolation technique has allowed us to remove proteases of extracellular digestion and to measure glycogen phosphorylase activity in lobster hepatopancreas. 4. 4. The glycogen phosphorylase activity seems to be mainly associated with R cells while it could not be detected in B cells.