Search

Widening the knowledge for fish injury and mortality mechanism caused by pressure, shear stress and blade strikes inside turbine was constructive for optimizing fish-friendly turbine design and turbine operation regime. A special designed test equipment was applied for simulating the rotating blade inside turbine passage, anesthetized fish (crucian carp) was placed on the route of the blade for strike tests. The fish length, blade thickness, strike angle, and strike speed were independent variables during the tests, the injury rate, degree of injury and mortality rate were analysed according to observation or anatomical examination after repeated tests. The injury types were classified into: imbalance, ribs broken, gill cover broken, internal hemorrhage and death. The injury severity was directly affected by strike speed under same blade thickness and fish length. The ratio of blade thickness and fish length also affect the injury rate. Multiple injuries can be observed on one fish after tests, and combined injuries are more likely to lead to death. In the fish-friendly turbine design, blade thickness in the leading edge and blade numbers shall be carefully considered and the rotational speed shall be calculated.

Hydraulic transient processes sometimes bring with it violent or dramatic unsteady phenomenon, which would interfere the normal operation or even damage the system. The start-up of a centrifugal pump with cavitation can lead to serious transient phenomenon. One dimensional calculation (Method of characteristics) was widely used to solve transient problems, but its drawback is lacking of details for the flow characteristics inside the pump, 3D simulation for transient process simulation needs huge computer resources. A simulation method that coupled MOC and 3D simulation (CFD) was frequently used for solving complex transient problems in these years. The results of the coupling simulation are usually complex when cavitation happens and disappears quickly during the short start-up period, a simplified method to describe the process is necessary. A centrifugal pump and its related system were simulated with a coupling method. Dimensionless mass flow rate, head and cavitation conditions of the pump was used to analyse the start-up process. It was proved that the non-dimensional study method can make the whole process more intuitive and easier to understand.

In recent years, under the influence of the upsurge of rural tourism, some Jiarong Tibetan villages are facing the dilemma of losing the color of environmental characteristics. In order to maintain the regional color personality of Jiarong Tibetan village and deepen the local understanding of the environmental color of Jiarong Tibetan village, this paper expounds the impression of environmental color of Jiarong Tibetan village, and taking Ganbao Tibetan Village in Lixian County as an example, deeply analyzes the causes of the environmental color of Ganbao Tibetan village from three dimensions: the influence of natural conditions, the gestation of local materials and the expression of inner belief. On this basis, it quantitatively analyzes the main color tone of Ganbao Tibetan village and the color attribute values of Riyue Square.

In this paper we investigate trans-impedance amplifiers which can be used to minimize the influence of stray capacitances on the operation of signal conditioners used for instrumentation applications such as inductive microsensors for micromachines. The effect of stray capacitances can be minimized when using this type of amplifier by ensuring that its input impedance is small. A technique for realizing very low input impedances over a wide bandwidth for these amplifiers is studied both analytically and experimentally for transistors having a wide range of gain - bandwidth products . In addition an improved circuit configuration which further reduces the amplifier's input impedance at high frequencies is investigated by computer simulation.

The influence of polarization on the two-dimensional structure of heterogeneous dumbbells is studied by Monte Carlo simulation. The dumbbell consists of two fused hard spheres whose centers are embedded with point dipoles and , respectively. The axis of the dumbbell can rotate freely in the x-y plane but and are always along the x-axis which is the polarization direction. When the dipolar strength ?a is much larger than ?b, the dumbbells are perpendicular to the polarization direction and form zigzag chains; when ?a and ?b are comparable, the dumbbells will form end-to-end chains if and are parallel, or side-by-side chains if and are antiparallel. All the chains are along the polarization direction and the detailed information about them is given through extracting the radial and angular distributions from the simulation results. Finally, we calculate the energies of four kinds of ideal chains to explain structural transition. Our simulation results can explain the very recent experiment by Nagao D. et al. (Langmuir, 28 (2012) 6546) which studied the assembly of dumbbells with inducible dipoles, where magnitude of the dipoles was frequency-dependent and by changing frequency, different assemblies could be obtained.

We report the synthesis and characterization of silicon doped MgB2 films fabricated by hybrid physical?chemical vapor deposition using silane as the doping source. Various amounts of Si up to 9% were added into MgB2 thin films, which were epitaxially grown in?situ on SiC. Compared with that of the undoped film, the superconducting transition temperature of the doped film does not show significant change; however the magnetic critical current density (Jc) has been increased. Jc for the film with 5.0?at.% doping goes up to 2.7 ? 105?A?cm ? 2 for a 3?T perpendicular field. And the slope of the upper critical field curve for the doped film is slightly higher than that for the undoped MgB2 film.