Photovoltaic measurements in carbon nanotube - Amorphous silicon core/shell nanowire

Carbon nanotube is one of the promising materials for exploring new concepts in solar energy conversion and photon detection. Here, we report the first experimental realization of a single core/shell nanowire photovoltaic device (2-4μm) based on carbon nanotube and amorphous silicon. Specifically, a multi-walled carbon nanotube (MWNTs) was utilized as the metallic core, on which n-type and intrinsic amorphous silicon layers were coated. A Schottky junction was formed by sputtering a transparent conducting indium-tin-oxide layer to wrap the outer shell of the device. The single coaxial nanowire device showed typical diode ratifying properties with turn-on voltage around 1V and a rectification ratio of 104 when biased at ±2V. Under illumination, it gave an open circuit voltage of ∼0.26V. Our study has shown a simple and useful platform for gaining insight into nanowire charge transport and collection properties. Fundamental studies of such nanowire device are important for improving the efficiency of future nanowire solar cells or photo detectors. © 2012 IEEE.

Excess pore pressures around underground structures following earthquake induced liquefaction

Underground structures located in liquefiable soil deposits are susceptible to floatation following an earthquake event due to their lower unit weight relative to the surrounding saturated soil. This inherent buoyancy may cause lightweight structures to float when the soil liquefies. Centrifuge tests have been carried out to study the excess pore pressure generation and dissipation in liquefiable soils. In these tests, near full liquefaction conditions were attained within a few cycles of the earthquake loading. In the case of high hydraulic conductivity sands, significant dissipation could take place even during the earthquake loading which inhibits full liquefaction from occurring. In the case of excess pore pressure generation and dissipation around a floating structure, the cyclic response of the structure may lead to the reduction in excess pore pressure near the face of the structure as compared to the far field. This reduction in excess pore pressure is due to shear-induced dilation and suction pressures arising from extensile stresses at the soil-structure interface. Given the lower excess pore pressure around the structure; the soil around the structure retains a portion of this shear strength which in turn can discourage significant uplift of the underground structure. Copyright © 2012, IGI Global.

一种模型驱动的交互式信息可视化开发方法

设计与实现面向领域应用的交互式信息可视化软件十分困难．缺乏统一的开发方法与支撑工具箱，为非专家用户提供对层次、网络、多维等数据类型的统一支持，对各种可视化技术与交互技术的统一支持，以及对信息可视化任务的统一支持．针对此问题，提出了一种模型驱动的交互式信息可视化开发方法Daisy．首先，提出了交互式信息可视化界面模型IIVM（interactive information visualization interface model）；然后，提出了基于IIVM的交互式信息可视化开发方法Daisy,讨论了该方法的两个核心技术：IIVM建模与描述文件生成方法、系统自动生成方法．同时，给出了Daisy工具箱，包括Daisy建模工具、Daisy系统自动生成工具以及运行时框架与组件库．最后，给出了该开发方法与工具箱的应用实例．实例表明，该方法能够为交互式信息可视化开发的统一支撑方法问题提供一种有效的解决方案．