FPGA给汽车电子带来新机遇

根据主要从事半导体及电子市行业市场调研的机构Databeans调查．电气和电子元件占一般汽车总成本约20％。该公司估计一辆2004年生产的低价位汽车上有150到180个电子元件．而现在生产的高价位汽车上则最少包含400个电子元件。     

Effects of nanotube helical angle on mechanical properties of carbon nanotube reinforced polymer composites

Carbon nanotubes (CNTs) possess exceptional mechanical properties and are therefore suitable candidates for use as reinforcements in composite materials. The CNTs, however, form complicated shapes and do not usually appear as straight reinforcements when introduced in polymer matrices. This results in a decrease in nanotube effectiveness in enhancing the matrix mechanical properties. In this paper, theory of elasticity of anisotropic materials and finite element method (FEM) are used to investigate the effects of CNT helical angle on effective mechanical properties of nanocomposites. Helical nanotubes with different helical angles are modeled to investigate the effects of nanotube helical angle on nanocomposite effective mechanical properties. In addition, the results of models consisting of helical nanotubes are compared with the effective mechanical properties of nanocomposites reinforced with straight nanotubes. Ultimately, the effects of helical CNT volume fraction on nanocomposite longitudinal modulus are investigated.     

Observations on the pre-harvest infestation of paddy by stored grain pests in Bangladesh

Investigations on the pre-harvest infestation of paddy by stored grain pests were carried out in the Dhaka district of Bangladesh. Paddy heads were drawn from fields located at various distances from rice and paddy stores at different times before harvest, and only Sitotroga cerealella Olivier emerged. No insects emerged from samples collected 12 days before harvest but numbers increased to around one per spikelet the day before harvest. Numbers decreased as the distance from the store increased from 10 to 1440 m.     

Saccadic overhead: information-processing time with and without saccades

Information-processing time was compared for serial and spatially distributed visual presentations with performance measures that permit the separation of total time into its during-display and post-display components. For all subjects, there was a significant saccadic overhead, that is, less time was required with the serial format, which allowed data access without eye movements. However, the magnitude of the overhead decreased as task complexity increased. All subjects were able to exercise some control over the distribution of total processing time, trading off short during-display times with longer post-display times and vice versa.     

Impedance of a monopole antenna over a ground plane and immersed in a magnetoplasma

A treatment of the input impedance of a monopole antenna over a ground plane covered with a magnetoplasma with any arbitrary direction of the static magnetic field is presented. The analysis is restricted to a cold plasma with uniaxial and quasi-static approximations. It has been found that for parallel and perpendicular directions of the static magnetic field with respect to the ground plane perfect mirror reflections can be obtained. For other directions of the static magnetic field, the reflection is birefringent so that the monopole impedance becomes modified over a dipole impedance. These modifications can be significant under hyperbolic plasma conditions. A short and a long monopole were considered. From laboratory measurements of a long monopole impedance, the resonance cone and the resonances corresponding to the antenna length have been observed.     

A self-aligned process for high-voltage, short-channel vertical DMOSFETs in 4H-SiC

In this paper, we describe a self-aligned process to produce short-channel vertical power DMOSFETs in 4H-SiC. By reducing the channel length to /spl les/0.5 /spl mu/m, the specific on-resistance of the MOSFET channel is proportionally reduced, significantly enhancing performance.