Synthesis of LiFePO4 with fine particle by co-precipitation method

LiFePO₄ is a potential candidate for the cathode material of the lithium secondary batteries. A co-precipitation method was adopted to prepare LiFePO₄ because it is simple and cheap. Nitrogen gas was needed to prevent oxidation of Fe²⁺ in the aqueous solution. The co-precipitated precursor shows the high reactivity with the reductive gas, and the single phase of LiFePO₄ is successfully synthesized with the aid of carbon under less reductive conditions. LiFePO₄ fine powder prepared by co-precipitation method shows high rate capability, impressive specific capacity and cycle property.     

Equivalent circuit model of on-wafer CMOS interconnects for RFICs

This paper investigates the properties of the on-wafer interconnects built in a 0.18-/spl mu/m CMOS technology for RF applications. A scalable equivalent circuit model is developed. The model parameters are extracted directly from the on-wafer measurements and formulated into empirical expressions. The expressions are in functions of the length and the width of the interconnects. The proposed model can be easily implemented into commercial RF circuit simulators. It provides a novel solution to include the frequency-variant characteristics into a circuit simulation. The silicon-verified accuracy is proved to be up to 25 GHz with an average error less than 2%. Additionally, equivalent circuit model for longer wires can be obtained by cascading smaller subsections together. The scalability of the propose model is demonstrated.     

Spectrum efficient region-based resource allocation with fractional loading for FH-OFDMA cellular systems

A practical resource management method that can significantly reduce cochannel interference (CCI) and improve spectrum utilisation in FH-OFDMA packet-based cellular networks is presented. The proposed method seeks an effective combination of dynamic resource allocation with fractional coding and bit loading to respectively minimise CCI and maximise system throughput for a desired performance.     

The relationship between photo-catalytic performance and optical property over Si-incorporated TiO2

This study focuses on the relationship between photo-catalytic performance and optical property over Si-incorporated TiO₂. The Si-incorporated TiO₂ particles exhibited a pure structure of anatase having a particle size of less than 20 nm and surface area of more than 190 m²/g. The absorbance did not shift to a higher wavelength in spite of the incorporation of the Si ions, but the intensity of the photoluminescence (PL) curve was the smallest in the case of the 2.0 mol% Si-TiO₂, which was related to the recombination between the excited electrons and holes. Based on these results, the photodecomposition of methyl orange in the liquid reaction was enhanced over the 2.0 mol% Si-incorporated TiO₂ compared with that over pure TiO₂: Methyl orange at 10.0 ppm was completely decomposed after 100 min when 1.0 g of the 2.0 mol% Si-incorporated TiO₂ was used.     

Integrated carbon nanotube field emission differential amplifier: Modeling and measurement of the common-mode rejection ratio

A novel integrated vacuum field emission (VFE) differential amplifier (diff-amp) utilizing carbon nanotube (CNT) emitters has been developed. A dual-mask microfabrication process was employed to achieve a VFE diff-amp by integrating identical CNT VFE transistors with built-in split gates and integrated anodes. The identical pair of triode amplifiers was well-matched in their device characteristics. The measured ac small-signal characteristics of the diff-amp showed a common-mode-rejection ratio (CMRR) of ~ 320 (~ 50 dB). The proposed analytical model of the CMRR was verified to be in good agreement with the experimental data. The successful implementation of the CNT diff-amp demonstrates a new way to achieve temperature and radiation tolerant VFE integrated microelectronics.     

Complementary effects of solid lubricants in the automotive brake lining

An experimental investigation was carried out to examine the tribological behavior of NAO (non-asbestos organic) type brake linings containing different volume ratios of graphite and antimony trisulfide (Sb₂S₃). A scale dynamometer was used for friction tests and particular emphases were given to the effect of applied pressure, sliding speed, and temperature on the coefficient of friction according to the relative amounts of the two solid lubricants. Results showed that the brake linings with both solid lubricants exhibited better friction stability and less speed sensitivity than the friction materials containing a single solid lubricant. In particular, the brake lining containing higher concentrations of graphite showed better fade resistance than others during high-temperature friction test.     

数控超声加工的初步工艺试验

介绍在经过数控化改造的两坐标超声加工机床上所进行数控超声加工的初步工艺试验,并讨论试验结果。     

Instability of solid–liquid interface in transitional metal–carbide systems

The instability of solid–liquid interface (ISLI) during the liquid-phase sintering was studied using carbide–Ni composites. Of the various transitional metal carbides TiC of 4th period is the only carbide that exhibits a strong ISLI with negative curvatures in molten Ni. No ISLI was observed for other carbides in the 5th and 6th periods. The origin of ISLI is strain developed at the interface between the carbides and the newly formed solid solutions. The difference in the size of the atoms involved can be used to predict the formation of a carbide–Ni solid solution when the Hume-Rothery rules are applied. Aside from the size factor, other factors in the rules are not effective in predicting this phenomenon.