Two-dimensional van der Waals materials have shown novel fundamental properties and promise for wide applications. Here, we report for the first time an experimental demonstration of the in situ characterization and highly reversible control of the anisotropic thermal conductivity of black phosphorus. We develop a novel platform based on lithium ion batteries that integrates ultrafast optical spectroscopy and electrochemical control to investigate the interactions between lithium ions and the lattices of the black phosphorus electrode. We discover a strong dependence of the thermal conductivity on battery charge states (lithium concentrations) during the discharge/charge process. The thermal conductivity of black phosphorus is reversibly tunable over a wide range of 2.45-3.86, 62.67-85.80, and 21.66-27.58 W·m·K in the cross-plan, zigzag, and armchair directions, respectively. The modulation in thermal conductivity is attributed to phonon scattering introduced by the ionic intercalation in between the interspacing layers and shows anisotropic phonon scattering mechanism based on semiclassical model. At the fully discharged state (x ∼ 3 in LiP), a dramatic reduction of thermal conductivity by up to 6 times from that of the pristine crystal has been observed. This study provides a unique approach to explore the fundamental energy transport involving lattices and ions in the layered structures and may open up new opportunities in controlling energy transport based on novel operation mechanisms and the rational design of nanostructures.

No abstract

No abstract

No abstract

Traditional ribbon microphones cannot be miniaturized owing to the sensitivity of the microphone in proportion to its ribbon length. A novel symmetrical voice coil instead of the traditional ribbon is proposed, designed, and optimized. The new structure of ribbon microphones was fabricated by microelectromechanical systems (MEMS) technology, which allows increasing the effective coil length while reducing the diaphragm dimension. The obtained results present a voice coil length of 77.5 mm under a limited ribbon length of 17 mm. Compared with the conventional ribbon microphones (with ribbon length 50 mm and voice coil length 50 mm), the diaphragm dimension was reduced but its effective length was increased by about 55%, from 50 mm to 77.5 mm. Moreover, the magnetic flux density in the air gap of the magnetic circuit by simulations and experiments is measured to be at 5.1 and 5 kG, respectively. (C) 2009 Society of Photo-Optical Instrumentation Engineers. [DOI: 10.1117/1.3142971

In this paper, we propose to combine the data from CKEO and KEO buoys and reanalysis data to study the prevailing wind types, temperature changes and carbon fluxes in the Kuroshio Extension in different seasons in recent years, in order to deepen our understanding of the physical and chemical environment and its evolution in the sea. In this paper, we analyze the characteristics of the wind field of the Kuroshio Extension using the CKEO buoy system at a fixed coordinate (149.25°E, 39°N) in the northwest Pacific Ocean, using four methods: wind speed and direction rose diagram, wind speed comparison line diagram, temperature comparison line diagram and carbon flux variation line diagram. Compared with the KEO buoy observation system, the CKEO buoy observation system provides high quality sea-air observation data in the Kuroshio Extension, which provides valuable information for the study of sea-air interaction in the Kuroshio Extension.