Intergranular Fracture of Lithium Fluoride–22% Calcium Fluoride Hypereutectic Salt at 800 K

Constant-velocity compression tests were conducted at 800 K on as-cast LiF-22 mol% CaF₂ hypereutectic salt with engineering strain rates varying between 1.8 × 10⁻⁶ and 2.3 × 10⁻¹ s⁻¹. Considerable stain hardening was observed during the initial stages of deformation, and the true stress-strain curves exhibited maxima. Plots of the true strain rate against the flow stress at the proportional limit and the peak stress exhibited a power-law relation with stress exponents of 7.7. Microstructural examination of the deformed specimens showed extensive grain-boundary cracking and cavitation. These results suggest that grain-boundary cracking and interfacial sliding is important for cavity nucleation at the grain boundaries and at the LiF-CaF₂ interfaces, and cavity growth and interlinkage, which appear to depend on the morphological differences between different grain boundaries, occur through the preferential failure of the weaker LiF phase.     

Development and pilot testing for virtual manufacturing tools with intelligent attributes

The use of synthetic and surrogate tools in training robots and planning events within virtual environments has tremendous potential in making the programming of complex machines simple and easy. For example, by designating tasks off-line with the virtual tools, attributes such as process planning and collision avoidance can be automatically and efficiently incorporated. In our research we have experimented with the use of attribute laden virtual tools in various tasks such as robotic-based grinding and welding processes. Such attribute laden virtual tools aid human operators in path planning as well as in making decisions about the process itself. In this paper we have tested our concepts of virtual tools and the use of attributes such as physical, reflex and command actions. Four sets of experiments were conducted with human subjects. Two kinds of virtual tools were used in these experiments, one with guide plane attributes and the other without them. One set of experiments using the head mounted display interface, tested human performance and evaluated the effect of the learning process in using the virtual tools. Results showed that there was marked improvement in task execution time using the tools laden with guide plane attributes over the unencumbered virtual tools. This paper discusses various future applications of these virtual tools in manufacturing. It is observed that unlike non-haptic visual interfaces, where no physical feed back is available to the user, attribute laden tools could provide a much easier interface to robots.     

MIMO-OFDM 在不同 turbo 编码率下的实验研究

多输入多输出正交频分复用(MIMO-OFDM)是4G 和5宽带无线通信中最重要的空间接口。MI-MO 可通过多路天线传输多种信号,OFDM 可将一条无线通道分隔成空间非常接近的大量子通道,从而提供更可靠的高速通信。研究结果表明,MIMO 还可以和其他接口联合使用,如时分多址(TDMA)和码分多址(CDMA)。MIMO and OFDM 的结合对高速数据传输是最实际的应用。利用不同的 turbo 编码率,误码率(BER)得到了改善。     

Phytochemical flavonols,carotenoids and the antioxidant properties of a wide selection of Fijian fruit,vegetables and other readily available foods

Frequent consumption of fruits and vegetables is associated with a lowered risk of cancer, heart disease, hypertension and stroke. This has been attributed to the presence of various forms of phytochemicals and antioxidants present in the foods, e.g. carotenoids and polyphenol compounds including flavonoids and anthocyanins. Seventy Fiji grown fruits and vegetables, and some other commonly consumed products, were analysed for their total antioxidant capacity (TAC), total polyphenol content (TPP), total anthocyanin content (TAT) as well as the major flavonol and carotenoid profiles. These data will be used to estimate the phytochemical and antioxidant intake of the Fijian population and will be a useful tool in future clinical trials.     

Folate contents of some selected Fijian foods using tri-enzyme extraction method

Folic acid and total folate contents of 18 common foods in the Fijian diet were assayed. Foods were purchased from the central and eastern parts of Viti Levu in Fiji. Tri-enzyme treatment was performed to release bound folates using protease and α-amylase, with chicken pancreas as the conjugase. The highest total folate content was recorded for egg yolk (Gallus domesticus) at 256 μg/100 g, followed by long beans (Vigna sesquipedalis) which contained 130 μg/100 g of total folate (fresh weight basis). The local leafy vegetable called Bele (Abelmoschus manihot) and the Drumstick leaves (Moringa oleifera) available in Fiji also had high total folate contents, above 100 μg/100 g (fresh weight basis). For the 18 foods studied, the content of folic acid ranged from 3 to 189 μg/100 g and the total folate content was in the range of 3–256 μg/100 g, indicating a very wide range of folate content in the foods studied.