3854 research outputs found
Sort by
High-rate Performance Electrospun Na0.44MnO2 Nanofibers as Cathode Material for Sodium-ion Batteries
No full textSodium-ion batteries (SIBs) are considered as one of the most promising candidates to replace lithium-ion batteries (LIBs), because of their similar electrochemical properties, and geographical limitations of lithium. However, searching for the appropriate cathode materials for SIBs that can accommodate structure change during the insertion and extraction of sodium ions is facing great challenges due to the relatively larger size of sodium ion. Na0.44MnO2 has recently attracted significant attention because its crystal structure exhibits two types of large channels formed by MnO6 octahedra and MnO5 square pyramids, which facilitate the transportation of sodium ions. However, suffering from the slow kinetics and structural degradation, its rate performance is still not satisfied. Here, we report the fabrication of two types of Na0.44MnO2 hierarchical structures by optimized electrospinning and controlled subsequent annealing process. One is nanofiber (NF) which demonstrates a superior rate performance with reversible specific capacity of 69.5 mAh g−1 at 10 C, attributed to its one-dimensional (1D) ultralong and continuous fibrous network structure; the other is nanorod (NR) which exhibits an excellent cyclic performance with reversible specific capacity of 120 mAh g−1 after 140 cycles, due to its large S-shaped tunnel structure with a single crystalline structure
Power Transfer System
Get PDFA power transfer system and method are provided for transferring power from an AC supply outputting an AC voltage. The system includes a controller and a primary rectifier coupled to the controller and to the AC supply for converting the AC voltage to a DC bus voltage. An inverter is coupled with the primary rectifier and the controller for converting the DC bus voltage to a primary AC voltage. A primary coil is connected to the inverter. A secondary coil is in communication with the primary coil for producing an induced AC voltage. A secondary rectifier is connected to the secondary coil for rectifying the induced AC voltage to a secondary DC voltage. At least one sensor is connected to the secondary rectifier for outputting a signal proportional to the secondary DC voltage and the controller is configured to vary the DC bus voltage based on the signal from the sensor
Extracting vibration characteristics of a guitar using finite element, modal analysis, and digital image correlation techniques
Get PDFThe sound quality generated by the guitar depends on the vibration characteristics (i.e. natural frequencies and mode shapes) of this instrument. Thus, it is of particular interest to the guitar manufacturers to be able to obtain global information about the characteristics of the guitar. Traditional sensors can only measure at discrete locations. However, digital image correlation (DIC) can measure full-field data on the surface of the structure. In the current paper, a finite element (FE) model of a guitar with free boundary configurations was developed using quadratic solid elements. An eigensolution was performed on the FE model to determine its natural frequencies and mode shapes. In order to validate the numerical results, a modal impact hammer test was performed on the instrument in a free configuration. Furthermore, a measurement was performed on the guitar using the DIC technique. In this measurement as well, the guitar was suspended in a free configuration, but was driven using a broadband acoustic excitation generated by a sound source. The response of the guitar to the excitation was recorded using a pair of high-speed cameras. The recorded images were processed to extract the natural frequencies and mode shape of the guitar
Treating Big Problems with Small Things: Applications of Magnetic Nanoparticles
Get PDFApplication of magnetic nanoparticles in the hyperthermia treatment of cancer
