Structure design of linear ultrasonic motor with a laminated U-shaped stator based on modal analysis

Featured by advantages of low speed, large torque, fast response and being free from external magnetic field interference, the linear ultrasonic motor enjoys fast development in recent years. The single layer U-shaped motor has a flat structure as it makes use of d31 effect of piezoelectric ceramics and adopts integrated vibrators, but its output force is unsatisfactory. In this paper, the structure of the linear ultrasonic motor with a laminated stator was proposed, which was made of two identically single U-shaped stators. The finite element model for stators of ultrasonic motor was built by ANSYS to carry out modal analysis and structure optimization. The workbench of the motor was designed by PROE, and then, the designed stators and workbench were processed and assembled into a motor. The swept-sine modal test was carried out to verify the feasible of the simulation. Finally, the mechanical performance of the laminated ultrasonic motor was tested, and comparison was also carried out with single layer U-shaped ultrasonic motor. The results showed that the maximum output force of the laminated motors increases by 40 % than that of single layer U-shaped motor, while the maximum velocity increased by 38 %, which showed that the mentioned design of the laminated ultrasonic motor was feasible. Finally, in order to further expand application of the linear ultrasonic motor designed in this paper, it was compared with the existing linear ultrasonic motors in terms of assembly and mechanical performances in this paper. It is shown that the linear ultrasonic motor designed has more prominent performances in these aspects

Theory for electric dipole superconductivity with an application for bilayer excitons

Exciton superfluid is a macroscopic quantum phenomenon in which large quantities of excitons undergo the Bose-Einstein condensation. Recently, exciton superfluid has been widely studied in various bilayer systems. However, experimental measurements only provide indirect evidence for the existence of exciton superfluid. In this article, by viewing the exciton in a bilayer system as an electric dipole, we provide a general theory for the electric dipole superconductivity, and derive the London-type and Ginzburg-Landau-type equations for the electric dipole superconductors. By using these equations, we discover the Meissner-type effect and the electric dipole current Josephson effect. These effects can provide direct evidence for the formation of the exciton superfluid state in bilayer systems and pave new ways to drive an electric dipole current.Comment: 10 pages, 5 figures, 1 Supplementary Informatio

Provision of secondary frequency regulation by coordinated dispatch of industrial loads and thermal power plants

Demand responsive industrial loads with high thermal inertia have potential to provide ancillary service for frequency regulation in the power market. To capture the benefit, this study proposes a new hierarchical framework to coordinate the demand responsive industrial loads with thermal power plants in an industrial park for secondary frequency control. In the proposed framework, demand responsive loads and generating resources are coordinated for optimal dispatch in two-time scales: (1) the regulation reserve of the industrial park is optimally scheduled in a day-ahead manner. The stochastic regulation signal is replaced by the specific extremely trajectories. Furthermore, the extremely trajectories are achieved by the day-ahead predicted regulation mileage. The resulting benefit is to transform the stochastic reserve scheduling problem into a deterministic optimization; (2) a model predictive control strategy is proposed to dispatch the industry park in real time with an objective to maximize the revenue. The proposed technology is tested using a real-world industrial electrolysis power system based upon Pennsylvania, Jersey, and Maryland (PJM) power market. Various scenarios are simulated to study the performance of the proposed approach to enable industry parks to provide ancillary service into the power market. The simulation results indicate that an industrial park with a capacity of 500 MW can provide up to 40 MW ancillary service for participation in the secondary frequency regulation. The proposed strategy is demonstrated to be capable of maintaining the economic and secure operation of the industrial park while satisfying performance requirements from the real world regulation market

An exotic fruit with high nutritional value: Kadsura coccinea fruit

This research was to determine nutritional composition, essential and toxic elemental content, and major phenolic acid with antioxidant activity in Kadsura coccinea fruit. The results indicated that Kadsura coccinea fruit exhibited the high contents of total protein, total fat, ash and essential elements such as calcium (Ca), ferrum (Fe) and phosphorus (P). The levels of four common toxic elements, i.e. cadmium (Cd), mercury (Hg), arsenic (As) and lead (Pb), were lower than legal limits. By high-performance liquid chromatography (HPLC) analysis, gallic acid was identified as major phenolic acid in peel and pulp tissues. Its contents were no significant difference in both tissues. In comparison with two commercial antioxidants, the major phenolic acid extracted from Kadsura coccinea exhibited stronger 1,1-diphenyl-2-picrylhydrazyl radical-scavenging activity and reducing power. Kadsura coccinea fruit is a good source of nutrition and natural antioxidant. It is worthwhile to popularize this exotic fruit around the world