超声相控阵检测焊缝三维可视化

介绍超声相控阵扇形（s型）扫查法对焊缝实施全体积检测的优势：信号（色码幅度）实时显示,自动存储,特别是检测数据可三维（5D）显示,又可多视角观测,缺陷四定（定位、定性、定量、定级）更方便,符合国际权威法规ASME最新版（2011a）的有关要求。期盼UT人员能在日常焊缝检测中熟练运用相控阵三维可视化技术。     

3D simulation of hydrogen ignition in a rapid compression machine

Low-temperature (at T < 900–950 K) ignition delays of hydrogen–air mixtures are mainly measured in rapid compression machines (RCM). This communication is aimed at numerical simulation of ignition delays of hydrogen–air mixtures in the RCM by means of a coupled three-dimensional (3D) Unsteady Reynolds-Averaged Navier–Stokes (URANS) – Particle Method (PM) simulation of RCM operation capable of catching turbulence–chemistry interaction. The study indicates that the time history of piston motion in an RCM affects the final state of a test mixture at the end of compression stroke and therefore influences the phenomena relevant to test mixture ignition. More specifically, the calculations show that different laws of piston motion at a fixed average piston velocity (i.e., fixed piston displacement and fixed compression time) and fixed compression ratio result in different evolution of mean pressure, temperature and velocity fields in the RCM test section leading to different ignition behavior. The reasons for the arising differences lie in the fact that the local instantaneous piston velocity determines the roll-up vortex structure, strength and turbulence dissipation in it, heat transfer in test-section walls, and mass leakage through piston rings.     

What is driving the EU burden-sharing agreement: Efficiency or equity?

Under the Kyoto Protocol the European Union agreed to reduce emissions of greenhouse gases by 8 percent. The Burden-Sharing Agreement (BSA) redistributes the reduction target among the member states. The purpose of this paper is to evaluate the BSA. To determine if cost efficiency was considered, marginal abatement costs (MACs) are first calculated based on an estimation of the directional output distance function using country production data for 1990-2000. MACs, together with equity indicators, are then regressed on the emission change targets. The main conclusion is that both efficiency and equity were important aspects considered in the settlement.     

西苕溪流域地表水与地下水相互作用特征!

为探寻西苕溪地表、地下水体的来源和补排关系,对西苕溪流域丰水期和平水期的地表、地下水进行了氢氧同位素(δD和δ18O)组成分析,并结合水体的水化学参数,推断其来源和补排关系。结果表明:西苕溪流域地表、地下水体主要接受降雨补给,在上游山区中的泉水运移过程较为缓慢,上游地表水与地下水补排关系不明显;中游丘陵地区地表、地下水体相互联系紧密,具体补排关系为3号、4号、6号样点处地表水接受地下水补给,其余样点处为地表水补给地下水;下游农田密集区地下水接受河水补给较少。     

Factor demand flexibility in the primary aluminium industry: Evidence from stagnating and expanding regions

The purpose of the paper is to analyse and compare short-run factor demand responses to price changes in the primary aluminium industry in Western Europe and the Africa-Middle East (AME) region. We outline a Translog variable cost function model, which is estimated employing a panel data set at the individual smelter level over the time period 1990-2003. The empirical results show evidence of limited - but far from insignificant - price-induced factor demand responses in the short-run. Overall aluminium smelters in the AME-region show evidence of higher estimated short-run own- and cross-price elasticities than their competitors in Western Europe, at least when it comes to labour and electricity demand. One important reason for this result is the greater number of pot lines with slightly different technologies at each smelter as well as the more intense use of the Prebake technology in the AME-region making retrofits in existing plants less costly than in Western Europe. The results also suggest that in both regions the demand for electricity has over time become less sensitive to short-run price changes, while the labour and material demand responses to price changes have increased but only in the AME-region. The liberalisation of the Western European electricity markets in combination with the rigid labour markets in this part of the world suggest that the shift in production capacity from the western world to the AME-region as well as China may continue.     

基于GIS的电力工程勘察信息系统设计研究

从分析电力行业工程勘察信息管理与利用现状入手,提出了基于地理信息系统GIS(以下简称GIS)的工程勘察设计一体化的设想,设计了工程勘察信息化集成应用系统的逻辑模型,阐述了系统所采用的组件式GIS和数据融合等关键技术,最后结合具体的工程实例,详细介绍了具有系统分析决策功能的任意工程地质剖面图的绘制和三维实体地层模型的构建...     

Biodegradation of Compostable Plastics in Green Yard-Waste Compost Environment

Compostable plastic materials, produced from polylactic acid (PLA), corn starch, or sugarcane, degraded in a green yard-waste compost environment. The compostable plastics claim to meet ASTM D6400 standards for biodegradation, sustainable plant growth, and eco-toxicity. Biodegradation was measured by disintegration studies over 20 weeks. The commercially available compostable products, made from PLA, sugarcane, or corn starch, biodegraded while in a commercial compost facility with other common yard waste compostable items. The PLA container, cup, and knife completely degraded in 7 weeks at a rate similar to the Avicell micro-cellulose control. The corn starch-based trash bag and sugarcane plate degraded at a similar rate as the Kraft paper control. The three materials degraded between 80% and 90% after 20 weeks.     

对转压气机三维掠动叶优化设计

为探索三维掠动叶降低对转压气机二次流损失的潜力,进一步提高对转压气机气动性能,基于近似函数与遗传算法,针对某对转压气机双排转子在整机环境下进行三维掠动叶优化设计,并对优化前后流场进行对比分析。优化成功的得到了双排“S”形掠动叶,结果表明:三维掠动叶有效改善了双排动叶吸力面径向二次流,减小了吸力面低速区,提高了对转压气机性能,优化工况点整机效率提高0.6%,全工况范围内效率均有所提高；三维掠动叶提高对转压气机效率的根本原因是其对径向负荷分配的重新调整,将叶展下方流动较差区域负荷移至叶展上方,改善流场的同时保证对转压气机负荷不变。 