Severn Barrage tidal power project: implications for carbon emissions

UK Government encouragement of the Severn Barrage project has regard for the fact that this is by far the largest single source of renewable energy available to the United Kingdom. A major concern for all forms of electricity generation is their effects of carbon emissions and, as a result which is now generally recognised, on global warming. The present paper makes use of published sources of carbon emissions data to estimate the carbon content of each of the operations required to produce, transport, construct, operate and decommission this barrage if it is located and designed as set out in 1989. The approach adopted here is based on estimating the ratio of the life-cycle carbon emissions demand of the scheme (gCO₂) relative to its energy output (kW) over an assumed lifetime, this to include expected plant replacements over that period.     

启动新一代移动宽带服务

对有线及无线服务供货商来说．这是一个最好的时代,也是一个最坏的时代。光是在北美,由于其他技术的替代作用,有线通信业者平均每天流失一万个用户。换言之．相当于每季流失100万个、每年流失400万个用户。此外,包含ABI Research在内的各家分析机构均指出,手机市场在未来5年内将持续萎缩。ABI预估,从2007年-2012年．手机市场的营收将以年复合增长率负8％的速度不断衰落,同时也反映出此市场未来的走势。     

Effect of Microstructural Features on Magnetic Properties of High-Carbon Steel

Metallurgical and Materials Transactions A - Industrially produced high-carbon steel has been heat treated in order to obtain various microstructures of the single phase of martensite, bainite,...     

Development of carbon conductive additives for advanced lithium ion batteries

The newly developed conductive carbon blacks C-NERGY™ Super C65 and C-NERGY™ Super C45 were studied with regard to their performance as conductive additives in positive lithium ion battery electrodes and compared to other reference conductive carbon blacks. The lowest electrical volume resistivity and highest compressibility were found for C-NERGY™ Super C45 dry-mixed with LiCoO₂ powder. Mixing by high shear forces in acetone dispersion improved the electrical resistivity and compressibility of the C-NERGY™ Super C65 containing LiCoO₂ mixture to the same level obtained for the C-NERGY™ Super C45 mixture in the same process. Acetone dispersions of C-NERGY™ Super C45 and LiCoO₂ showed the lowest viscosities attributed to the carbon black's specific BET surface area of 45 m² g⁻¹ being the lowest of all carbon blacks studied. The easy dispersibility of C-NERGY™ Super C45 in LiCoO₂ could be explained by its particular surface group chemistry characterized by time-of-flight secondary ion mass spectrometry. The electrical volume resistivity of the LiCoO₂/carbon black mixtures was in line with the high current rate performance of half-cells with related LiCoO₂ electrodes. Compared to the investigated carbon blacks, the electrical volume resistivity of the graphite conductive additives C-NERGY™ KS6L and C-NERGY™ SFG6L at different concentrations in LiCoO₂ powders showed higher critical volume fractions but lower ultimate resistivity levels. Adding one of these graphites to the carbon black conductive mass improved the electrode density and, at concentrations above the critical volume fraction of the graphite component, significantly decreased the ultimate resistivity level of the LiCoO₂ electrode mass.     

基于DSC控制的数字功率因数校正模块应用

数字控制技术和电力电子应用之间结合逐渐紧密,功率因数校正(PFC)是电力电子技术的一个重要应用,本文利用Freescale公司新数字信号控制器(DSC)MC56F8323,完成了基于DSC的功率因数校正模块应用研究.本文提供了PFC变换器的完整数字控制解决方案,包括改进的数字PFC算法设计、适用于数字控制特点的变换器模型分析和控制参数推导、基于DSC的PFC变换器的系统软件设计、以及PWM控制信号产生策略等,最后用一台500W实验样机验证了数字控制的优良系统性能.     

Inter-Tissue Differences in Fatty Acid Incorporation as a Result of Dietary Oil Manipulation in Port Jackson Sharks (Heterodontus portusjacksoni)

Fatty acid profile analysis is a tool for dietary investigation that may complement traditional stomach contents analysis. While recent studies have shown that the liver of sharks fed different diets have differing fatty acid profiles, the degree to which diet is reflected in shark blood serum and muscle tissue is still poorly understood. An 18-week controlled feeding experiment was undertaken using captive Port Jackson sharks (Heterodontus portusjacksoni). Sharks were fed exclusive diets of artificial pellets treated with fish or poultry oil and sampled every 6 weeks. The fatty acid profiles from liver, blood serum, and muscle were affected differently, with the period from which significant differences were observed varying by tissue and diet type. The total fatty acid profiles of fish oil and poultry oil fed sharks were significantly different from week 12 onwards in the liver and blood serum, but significant differences were only observed by week 18 in the muscle tissue of sharks fed different diets. The drivers of dissimilarity which aligned with dietary input were 14:0, 18:2n-6, 20:5n-3, 18:1n-9 and 22:6n-3 in the liver and blood serum. Dietary fatty acids accumulated more consistently in the liver than in the blood plasma or muscle, likely due to its role as the central organ for fat processing and storage. Blood serum and muscle fatty acid profiles were influenced by diet, but fluctuated over-time. The low level of correlation between diet and muscle FA profiles is likely a result of low levels of fat (<1 %) in the muscle and the domination of structural, cell-membrane phospholipids in shark muscle tissues. Our findings describe inter-tissue differences in the incorporation of fatty acids from the diet to consumer, which should be taken into account when interpreting dietary patterns from fatty acid profiles.     

Case studies of groundwater flow into tunnels and an innovative water-gathering system for water drainage

Groundwater inflow into tunnels can constitute a potential hazard and also is an important factor influencing the speed of tunnel excavation. In this paper the results of numerical modelling are presented to investigate the groundwater flow and the distribution of the pore pressure around tunnels. Two types of tunnels, double-arch tunnel and twin-tube tunnel, were studied. Potential leakage places are identified for the two types of tunnels. The most permeable place in the double-arch tunnel is at the contact interface between the middle wall and the overlying rock. The results of numerical modelling are compared with field observations in the case studies. Based on the results of numerical modelling and the field investigations, an innovative water-gathering system for reducing water leakage was proposed and applied in some tunnels on ChangJi Expressway in China. The water-gathering system can be quickly glued to the rock surface and easily installed for tunnelling. It can be applied in tunnels where water-bearing fractures are well-developed in the rock mass.