Sustainability of the Dujiangyan Irrigation System for over 2000 Years–A Numerical Investigation of the Water and Sediment Dynamic Diversions

The Dujiangyan Irrigation System (DIS), located in the western portion of the Chengdu Plain at the transitional junction between the Qinghai-Tibet Plateau and Sichuan Basin, has been in operation for about 2300 years. The system automatically uses natural topographical and hydrological features and provides automatic water diversion, sediment drainage and intake flow discharge control, thus preventing disastrous events in the region in a ‘natural’ way. Using a numerical modeling approach, this study aims to investigate the reasons behind this natural behavior of the system and provide a better understanding of the complex mechanisms which have caused the sustainability of the DIS for over two millennia. For this purpose, a two-phase flow model based on the Shallow Water Equations (SWEs) is developed to simulate the fluid and sediment motions in the DIS. A coupled explicit-implicit technique based on the Finite Element Method is applied for the fluid flow and a Sediment Mass (SM) model in the framework of the Lagrangian particle method is proposed to simulate the sediment motion under different flow discharge conditions. The results show how different components of the DIS make full use of the hydrodynamic and topographical characteristics of the river to effectively discharge sediment and excess flood to the downstream and create an environmentally sustainable irrigation system.

Elastic Properties of Rhombus Dodecahedron Open-Cell Cellular Materials

Based on the principle of pore formation, geometrical model to describe open-cell cellular materials was constructed. The model is rhombus dodecahedron cell shapes with circle-strut and transitional-junction. The dependence of relative density on the microstructure of the model was analyzed; by finite elements method, the relative elastic modulus of the model was calculated, the influence of microstructure and relative density on the elastic modulus was also obtained. The results show that circle-strut radius and transitional-junction curvature radius are the primary factors on relative density increment; nonlinearity of relative density on relative elastic modulus is similar to that of circle-strut radius on relative elastic modulus, is obviously greater than that of transitional-junction curvature radius on relative elastic modulus.

Parametric Modeling of Transition Tube with Constant Section Area along Straight, Circular and Oblique Central Route on CATIA

Parametric modeling of transition tubes were implemented based on constant cross section area assumption along the main central routes on CATIA software. The key objective of modeling these similar structures is to provide more geometric configuration options and modifications of micro channels for multi phase flow systems. The modeling processes were parameterized and analyzed by CATIA “Generative Shape Design” module with the help of “Parameters” and “Relations” functions. The surface models are all designed in circular cross sections that are constrained in two ways: one is perpendicular to the main central routes of the tube for planar transitional junction, and another is, perpendicular to the sub-branch central routes for oblique transitional junction three dimensionally. Next work is emphasized on numerical simulation and experimental investigation with these geometric structures in a multi phase flow system.

The Transitional Junction: A New Functional Subcellular Domain at the Intercalated Disc

We define here a previously unrecognized structural element close to the heart muscle plasma membrane at the intercalated disc where the myofibrils lead into the adherens junction. At this location, the plasma membrane is extensively folded. Immunofluorescence and immunogold electron microscopy reveal a spectrin-rich domain at the apex of the folds. These domains occur at the axial level of what would be the final Z-disc of the terminal sarcomere in the myofibril, although there is no Z-disc-like structure there. However, a sharp transitional boundary lies between the myofibrillar I-band and intercalated disc thin filaments, identifiable by the presence of Z-disc proteins, α-actinin, and N-terminal titin. This allows for the usual elastic positioning of the A-band in the final sarcomere, whereas the transduction of the contractile force normally associated with the Z-disc is transferred to the adherens junctions at the plasma membrane. The axial conjunction of the transitional junction with the spectrin-rich domains suggests a mechanism for direct communication between intercalated disc and contractile apparatus. In particular, it provides a means for sarcomeres to be added to the ends of the cells during growth. This is of particular relevance to understanding myocyte elongation in dilated cardiomyopathy.

Morphogenesis of Fusarium sp-Induced Tibial Dyschondroplasia in Chickens

Tgibial dyschondroplasia was induced in female broiler chicks by the incorporation of 2% Fusarium roseum “Alaska” culture into their starter ration. Chicks were placed on this diet at one day of age and maintained until they were killed at four days or one week. Proximal tibial physes were grossly thickened into cone-shaped masses of cartilage by one week of age. Microscopically, lesions were in both ages of treated chickens and were characterized by thickening of the transitional zone which was especially prominent in the center of the growth plate. This zone was unmineralized, avascular, and contained chondrocytes which were crenated and densely eosinophilic. The cartilage matrix was pale and contained some patchy eosinophilic foci. Four growth plates with tibial dyschondroplasia and four normal growth plates from each of the four-day and one-week-old age groups were evaluated based on the following parameters: number of metaphyseal vascular sprouts, distance between the proliferative/transitional junction and the tip of the metaphyseal vascular sprouts, width of the tips of the metaphyseal sprouts, distance between tips of adjacent metaphyseal vascular sprouts, and number of perforating vessels in the proliferative zone. The distance between the proliferative/transitional junction and the metaphyseal sprout tips was greatly increased (p < 0.01) in the affected four-day and one-week-old chickens compared to age-matched controls. Fusarium sp-induced tibial dyschondroplasia morphologically resembles spontaneous and chloride-induced tibial dyschondroplasia and tibial dyschondroplasia may, therefore, represent a common end-point lesion derived by several pathogenetic mechanisms.