Home, School, Borrowed, Public or Mobile: Variations in Young Singaporeans' Internet Access and Their Implications

This paper studied uneven Internet access amongst young people in Singapore. The study finds that young Singaporeans access the Internet mainly through home, school, borrowed, public, and mobile sources, with different implications for each type of Internet access. For those with home or mobile access, Internet use was routinised and often intense, even burdensome and distracting on occasions. For those who relied on borrowed, school, or public access, intermittent use appeared adequate but hampered their ability to hone online skills to the levels of their peers. The study also finds that although systematic incorporation of IT into the national curriculum can encourage parity in basic exposure to online skills, developing greater Internet proficiency is more likely with home Internet access.     

Effects of nodule treatment of rolled copper on the mechanical properties of the flexible copper-clad laminate

Rolled copper foil of 18 μm thickness underwent nodule treatment via electro plating in a solution containing dissolved CuSO₄ and NiSO₄. The product formed on the surface of the copper foil varied from copper oxides to nickel compounds of the sphere type with increasing current density and plating time. The highest surface roughness and maximum peel strength of 680 gf/cm were obtained with the formation of nickel compounds at a current density of 1.5 A/dm² and plating time of 30 s. In addition, the fracture location varied according to the plating parameters and occurred at the interface between the polyimide film and adhesive layer at the condition of the maximum adhesion strength.     

甲烷在1.637μm直接吸收光谱的理论计算和实验比较

介绍一种用Visual Basic 6. 0 实现快速Voigt 拟合的方法,并理论计算了甲烷位于 1637. 64～1637. 85cm- 1 (真空中) 的2v3 带R9 支的直接吸收谱,和实验测得的数据进行了比较,实验结果与理论计算吻合较好,结果表明Visual Basic 6. 0 和Fort ran 6. 0 相比完全能够满足精度需要,充分验证了Voigt 展宽理论,以及R. J .Wells 的算法在误差范围内的正确性。此拟合方法可运用到气体光谱研究当中去。     

盘石头水库施工交通桥软弱地基处理措施

沉井施工技术在工业与民用建筑、公路、桥梁等专业的应用较为广泛,在水利水电施工中较为少见。引用沉井施工技术,对盘石头水库泄洪(兼导流)洞工程施工交通桥桥基软弱地基进行了处理：①解决了河滩料严重渗水问题,避免了水流对桥墩基础的冲刷;②提高了桥墩基础的承载能力,保证了施工交通桥的运行安全;③降低了工程的施工难度,减少了施工工程量,节约了施工成本,加快了工程的施工进度,促进了盘石头水库的全面建设。     

INFLUENCE OF HYDROPEAKING ON INVERTEBRATES AND THEIR RELATIONSHIP WITH FISH FEEDING HABITS IN A PYRENEAN RIVER

The Orlu hydroelectric power plant on the River Oriège is managed by ‘hydropeaking’ and generates significant and frequent daily fluctuations in flow downstream. Observations at this site aimed to determine the impact of these variations on the aquatic environment. Surveys were carried out in June and October, upstream and about 2 km downstream of the plant, with a view to studying fish feeding habits and nutritive resources. In June, when the natural river flow was high, invertebrate populations differed very little between the two sectors. In October, after the low-water period, density and biomass were significantly lower in the downstream sector than they were upstream. Invertebrate drift was studied by taking samples every hour over a 24-hour cycle. Upstream, this drift showed a clear daily rhythm, dominated by nocturnal drift. Downstream in June, invertebrate drift was more abundant than upstream; a similar nychthemeral rhythm was apparent, but there were significant peaks during hydropeaking. In October, this daily rhythm disappeared, and drift was extremely low when river flow was low; on the other hand, a marked increase was observed during hydropeaking. Fish feeding habits were studied parallel to drift by capturing about 20 fish every four hours and analysing their stomach contents. No clear rhythm in the daily food uptake was observed. Stomach content was more abundant downstream. Lastly, the number of prey captured by fish at a given period of the day did not appear to be linked with the effective quantity of invertebrates simultaneously available in the river.     

Effects of precursor pH and sintering temperature on synthesizing and morphology of sol–gel processed mullite

Needlelike mullite, which shows high aspect ratios, has been synthesized by coprecipitation from aluminum nitrate enneahydrate and colloidal silica sols. The effects of precursor pH and sintering temperature on the synthesizing behavior and the morphology of the needlelike mullite have been investigated. The equilibrium mullite phase appeared in the samples, which had been sintered at and above 1200 °C for each precursor pH. Crystallization of cristobalite from excessive SiO₂ occurred during sintering from 1200 °C, and the amount of cristobalite increased with sintering temperature up to 1400 °C. However, resorption of cristobalite into mullite decreased the amount of the phase from 1500 °C. The mullite synthesized with precursor pH2 (acidic sample) displayed high aspect ratios at high sintering temperature. However, morphology of the mullite synthesized with precursor pH8 (basic sample) transformed to rodlike or granular shape with increasing sintering temperature.     

Preparation of Al2TiO5 from alkoxides and the effects of additives on its properties

Al2TiO5 was prepared by the sol-gel method from alkoxides and its mechanical and thermal properties measured. The prepared Al2TiO5 powder was very fine and had a narrow particle-size distribution. The addition of mullite and Al2O3 to the prepared Al2TiO5 inhibited the grain growth during sintering, resulting in a decrease of microcracking and an increase of fracture strength. Al2TiO5/mullite composite exhibited a higher fracture strength than Al2TiO5/alumina composite. The thermal expansion coefficient of Al2TiO5 increased with the addition of mullite and alumina, and also increased with temperature up to 1000°C; however, it decreased in the temperature range between 1000 and 1200°C during heating, due to decomposition of Al2TiO5. The addition of mullite inhibited the decomposition of Al2TiO5, but the addition of Al2O3 accelerated it. Al2TiO5 prepared from metal alkoxides was also more stable than that prepared from the commercial alumina and titania powders. This revised version was published online in November 2006 with corrections to the Cover Date.     

A general SFN structure with transmit diversity for TDS-OFDM system

In the digital television terrestrial broadcasting, the Single Frequency Network (SFN) has much advantage. SFN can serve an arbitrary large area with the same information broadcasted at the same frequency, resulting in the potential diversity gain. To improve the transmission performance of the Time Domain Synchronous-Orthogonal Frequency Division Multiplexing (TDS-OFDM) system in SFN, a general SFN structure with transmit diversity is introduced, theoretically analyzed and computer simulated. The proposed SFN structure is flexible to set up. Simulations show that this method can greatly improve the reliability of the signal transmission over the frequency selective fading channels and is suitable for the TDS-OFDM system in SFN.     

Development of an improved soya protein-lipid film

Soya protein-lipid film, an oriental food material, as traditionally prepared is limited in methionine and has inferior physical properties. A simple modification to the traditional method of preparation, involving addition of DL-methionine and glycerol to soya milk before film formation, yielded a product which was nutritionally improved and obviated the need to reconstitute it.